Prop Rotation
sirlan...@hotmail.com
clockwise when viewed from the rear. It had been my understanding
that British props rotated counter-clockwise. Heard of some stories
of uninformed American pilots, flying British planes for the first
time, automatically applying the wrong rudder on takeoff and going off
into the weeds. However, was watching some show the other night and
observed some British props rotating clockwise and other
counter-clockwise. Can anyone offer some explaination?
Mel Shettle
Steven P. McNicoll
<sirlan...@hotmail.com> wrote in message
news:3a5502d8....@nntp.atl.mediaone.net...
>
> All American props, with the exception of one of the P-38's, rotate
> clockwise when viewed from the rear.
>
There are more exceptions than that!
Erik Shilling
sirlan...@hotmail.com wrote:
Heard of some stories
>of uninformed American pilots, flying British planes for the first
>time, automatically applying the wrong rudder on takeoff and going off
>into the weeds.
You don't automatically aply right or left rudder on take off or any other
time. YOU keep the nose straight. anyone who would do this is not much of a
pilots.
Regard,
Erik
QDurham
> However, was watching some show the other night and observed some British
props rotating clockwise and other
counter-clockwise. Can anyone offer some explaination?>
Almost certainly an artifact of the TV/Movie camera.
Quent
Ponce de Leon
clockwise when viewed from the rear. It had been my understanding
> that British props rotated counter-clockwise. Heard of some stories
> of uninformed American pilots, flying British planes for the first
> time, automatically applying the wrong rudder on takeoff and going off
> into the weeds.
Idiot assumption!
Anyone, who calls himself a pilot can feel torque and apply in the proper
rudder correction. How dumb to think that a story was written as you
describe. The fact that you entertained the validity of the idiot author
reflects badly upon your intelligence.
Other than that; you, sir are a moron!
> Mel Shettle
>
Ponce de Leon
<sirlan...@hotmail.com> wrote in message
>Can anyone offer some explaination?
The word is EXPLANATION, you idiot!
>
> Mel Shettle
>
Steven P. McNicoll
"Ponce de Leon" <saa...@aug.com> wrote in message
news:t5a8lpj...@corp.supernews.com...
>
> Idiot assumption!
>
> Anyone, who calls himself a pilot can feel torque and apply in the proper
> rudder correction. How dumb to think that a story was written as you
> describe. The fact that you entertained the validity of the idiot author
> reflects badly upon your intelligence.
>
> Other than that; you, sir are a moron!
>
I suggest you consider switching to decaf.
Steven P. McNicoll
>
> The word is EXPLANATION, you idiot!
>
While it is possible that Mr. Shettle is an idiot, that cannot be determined
by anything in this forum. What can be determined is that you are an
asshole.
C.C.Jordan
Yeah, I can picture some lunk standing on a rudder pedal as he releases
the brakes and pushes the throttle up... Might be fun to watch... from a
distance.
My regards,
C.C. Jordan
http://www.worldwar2aviation.com
http://www.cradleofaviation.org
sirlan...@hotmail.com
prop pilots put a certain amount of rudder trim in prior to takeoff to
counter the expected yaw. This would be very hard to overcome if the
yaw was from the opposite side and could result in one leaving the
runway. I will also put my 35 years of aviation experience in the
Navy and Delta Aairlines Lines against yours anytime. Next time watch
out who you call a moron.
On Thu, 4 Jan 2001 20:24:58 -0500, "Ponce de Leon" <saa...@aug.com>
wrote:
C.C.Jordan
>If you knew what you were talking about asshole, you would know that
>prop pilots put a certain amount of rudder trim in prior to takeoff to
>counter the expected yaw.
Yes, but a little trim won't counteract torque on a high powered
fighter turning a large propeller. IIRC, the pre-takeoff trim is to
counter the assymetrical slipstream from the prop impinging on
the vertical stabilizer, which will cause yaw.
Ulf
It's really quite simple: You just write an answer like a normal and sane
person would, then cut-and-paste it into the upper box. Press "Oh yeah?"
and - Voila! It's rude, pointless and insulting posts made easy - should
save you lots of time!
--
Ulf
--Dulf at Yahoo dot Com
"Ponce de Leon" <saa...@aug.com> skrev i en meddelelse >
Cub driver
It was my belief that the Brits always got this backwards :)
The most famous case being the P-38, which in US Army service had one
prop turning clockwise as seen from the cockpit and the other one
turning counter-clockwise. Pilots used this oddity for fast escape
turns, chopping one throttle and advancing the other to get a torque
boost in the turn.
The Brits insisted that both props turn the "wrong" way. As a result,
the export Lightnings were very difficult to handle and were not much
used.
Your story of American pilots making the wrong correction is very
plausible. I only fly a 65 hp engine, but from my experience the
application of right rudder (the plane wants to turn left upon
application of full throttle and again when the tail comes up) is so
instinctive that I'm really not aware that I'm doing it.
There is also the famous story of the British pilot flying a Tomahawk
(P-40) built for the French, whose throttle was "advanced" by pulling
it aft. He came in, realized he was overshooting the runway,
firewalled the throttle, and pancaked at the end of the runway. When
the erks pulled him out, he said: "No wonder the bloody Frogs lost the
war!"
all the best - Dan Ford
Remains (a story of the Flying Tigers)
http://danford.net/remains.htm
Steven P. McNicoll
"Cub driver" <9...@danford.net> wrote in message
news:3a55b7a8...@news.MA.ultranet.com...
>
> The most famous case being the P-38, which in US Army service had one
> prop turning clockwise as seen from the cockpit and the other one
> turning counter-clockwise.
>
Well, the P-38 is certainly famous for counter rotating propellers, but I'd
say the most famous aircraft with that feature is the Wright Flyer.
Dudley Henriques
"Steven P. McNicoll" <ronca...@writeme.com> wrote in message
news:t5bk8jg...@corp.supernews.com...
All this is true about the 38 and the Wright Flyer, and I might have read
the original post incorrectly, but I'm getting another picture of the
poster's question. From the wording of his post I believe he was asking
about torque correction in single engine aircraft counter cranked as opposed
to US aircraft. I don't believe anyone has addressed that issue in any
detail, but instead addressed counter rotating propellers on twins. He
referenced using the "opposite foot" on take off, which would indicate a
single. There was no torque, P factor, or slipstream effect correction
needed on the counter rotating P38's, so I'm just assuming his question
still needs to be addressed.
--
Dudley A. Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI/ Retired
Jim Erickson
>clockwise when viewed from the rear. It had been my understanding
>that British props rotated counter-clockwise. Heard of some stories
>of uninformed American pilots, flying British planes for the first
>time, automatically applying the wrong rudder on takeoff and going off
>into the weeds. However, was watching some show the other night and
>observed some British props rotating clockwise and other
>counter-clockwise. Can anyone offer some explaination?
>Mel Shettle
Bristol radial engines had props that rotated counter-clockwise, while
British in-line engines, such as the Merlin, rotated clockwise. I have
no idea of the reason for this, but one consequence was that Lancaster
IIs (Bristol Hercules powered), and Beaufighter Mk IIs (Merlin powered),
had props that rotated in a different direction from all other marks.
Jim Erickson
Bill Kambic
> If you knew what you were talking about asshole, you would know that
> prop pilots put a certain amount of rudder trim in prior to takeoff to
> counter the expected yaw.
True, but this should be covered in the "manual." I will presume that anyone
getting into a high performance aircraft would have, at a minimum, read the
manual. If they did not then they are a First Class candidate for the
Darwinian Award.
> This would be very hard to overcome if the
> yaw was from the opposite side and could result in one leaving the
> runway.
True enough. But as the throttle is applied you feel the yaw and react
accordingly. If you were "spring loaded" to push right rudder then you might
have a moment of confusion. On a normal take-off this might not be much of a
problem, it would just cause a little "burble." The real test would be on a
close in, low altitude wave off where you would have rapid application of
power. Now if you press the wrong rudder you could end up in a world of hurt.
This is an interesting question. Could one of our Across the Pond
participants tell us why British engines go backwards!<g> (Other than it is a
continuation of other backwards tendencies, like driving on the wrong side of
the road.<g>)
Bill Kambic, Bright Star Farm, Kingston, TN
http://www.geocities.com/Heartland/Hills/1816
Mangalarga Marchador: Style, Stamina, Symmetry, Smoothness
Bill Horne
rotated CW, and some were CCW. I was surprised the first time I saw a
photo of a Hurricane that showed a prop that obviously went CW. I think
most Brit were CCW.
Regarding the P-38. I read that the original intent was to have the
right (from cockpit) prop turn CCW, and the left CW. This should have
given the best single engine characteristics. However, due to some
undesirable air flow problems, the setups were switched to the opposite
sides.
Bill Horne
Ponce de Leon
<sirlan...@hotmail.com> wrote in message
> If you knew what you were talking about asshole, you would know that
> prop pilots put a certain amount of rudder trim in prior to takeoff to
> counter the expected yaw.
I never knew one, we just felt our way thru the take-off role, meathead.
I will also put my 35 years of aviation experience in the
> Navy and Delta Aairlines Lines against yours anytime.
Were you a Cook in the Navy and a Baggage Handler with Delta? Seems like it!
Next time watch
> out who you call a moron.\
Sorry, Meathead!
Ponce de Leon
Takes one to know, etc!
Steven P. McNicoll
"Dudley Henriques" <dhenr...@earthlink.net> wrote in message
news:Q8l56.6392$1G4.2...@newsread2.prod.itd.earthlink.net...
>
>
> All this is true about the 38 and the Wright Flyer, and I might have read
> the original post incorrectly, but I'm getting another picture of the
> poster's question. From the wording of his post I believe he was asking
> about torque correction in single engine aircraft counter cranked as
> opposed to US aircraft. I don't believe anyone has addressed that issue
> in any detail, but instead addressed counter rotating propellers on twins.
> He referenced using the "opposite foot" on take off, which would indicate
> a single. There was no torque, P factor, or slipstream effect correction
> needed on the counter rotating P38's, so I'm just assuming his question
> still needs to be addressed.
>
It does, my comments were directed solely at the premise, "All American
props, with the exception of one of the P-38's, rotate clockwise when viewed
from the rear." There were a fair number of American aircraft in addition
to the P-38 that had propellers that turned "backwards".
Steven P. McNicoll
>
> Takes one to know, etc!
>
Perhaps I'm just an amiable proctologist.
David Lesher
Given you have a twin with counter-rotating props; what are the
differences between having the right engine going CW, and left CCW;
and the opposite -- the right going CCW and left CW...
And why is that?
--
A host is a host from coast to coast.................wb8foz@nrk.com
& no one will talk to a host that's close........[v].(301) 56-LINUX
Unless the host (that isn't close).........................pob 1433
is busy, hung or dead....................................20915-1433
C.C.Jordan
>Regarding the P-38. I read that the original intent was to have the
>right (from cockpit) prop turn CCW, and the left CW. This should have
>given the best single engine characteristics. However, due to some
>undesirable air flow problems, the setups were switched to the opposite
>sides.
This problem cropped up early in the program. There was some elevator buffeting
that Lockheed's aerodynamicists traced to propwash tumbling off of the inboard
wing sections. Fortunately, they realized that reversing the direction of
rotation would eliminate that. So, the right engine was exchanged with the
left engine and the problem was fixed, literally overnight. There were many
additional refinements in the aerodynamics of the P-38, right up throught
the P-38E. Of course, the final refinement came with the elimination of the
leading edge intercooler ducts and the drum type intercoolers themselves.
These were replaced with conventional core intercoolers and that resulted
in the deepening of the chin of the naceles. This appeared on the P-38J.
A similar problem was discovered with the XP-82. As it rolled down the
runway for its maiden flight accelerating at full throttle, the fighter
simply refused to fly. After defueling most of the onboard avgas, the plane
finally lifted off for a short wobbly flight. For some unknown reason, there
simply was not enough lift. North American engineers racked their brains
trying to figure out what was wrong. Finally they hit upon it. The original
XP-82 had outwardly rotating propellers. It seems that the outward rotation
generated a slipstream that stalled the center span of the wing. Just like
Lockheed done 6 years before, they simply switched engines from side to
side so that the blade tips met on the way down (instead of on the way up)
and the problem was cured.
So why did the solution reverse itself with the XP-82? Well, if we compare
the two aircraft, we see that the P-38 had a central fuselage that separated
the prop tips, and did not have a center span wing. In each case, the engineers
realized that blade orientation was the culprit. In the case of the XP-38, the
upward rotation of the outboard blades caused the slipstream to beat on the
elevator. In the case of the XP-82, it was the upward rotation of the inboard
blades that forced the slip stream to flow under the center span section,
effectively stalling the airfoil. At least, those are the explanations provided
by the aero wizards.
Gord Beaman
Dudley I read that differently still, I thought he was asking what the
difference would be between a twin with the port 'engine' rotating left and the
stbd 'engine' rotating right AS OPPOSED TO A TWIN with the PORT engine rotating
RIGHT and the STBD engine rotating LEFT...I think there'd be no difference in
this scenario, and I agree that there's no torque, P factor etc on
contra-rotating props. (or is it counter-rotating? - never can remember!).
--
Gord Beaman
PEI Canada.
Gord Beaman
>On Fri, 05 Jan 2001 04:10:36 GMT, sirlan...@hotmail.com wrote:
>
>>If you knew what you were talking about asshole, you would know that
>>prop pilots put a certain amount of rudder trim in prior to takeoff to
>>counter the expected yaw.
>
>Yes, but a little trim won't counteract torque on a high powered
>fighter turning a large propeller. IIRC, the pre-takeoff trim is to
>counter the assymetrical slipstream from the prop impinging on
>the vertical stabilizer, which will cause yaw.
>
>My regards,
>C.C. Jordan
>
And further to that, why would a little (or a lot for that matter) of rudder
trim have much effect till you get a respectable amount of airspeed in hand?.
The Lancaster had a vicious swing to port at the start of the takeoff roll,
required almost full right rudder to counteract it right at the beginning, then
lesser and lesser amounts as the rudder became more effective.
Gord Beaman
Yeh...might be even more fun if he's performing a 'max rate take off' where you
stand on the brakes, apply as near as you can to max power then release the
binders...HooWee!...likely get well into a ground loop before he could fumble
the power off!...
Gord Beaman
>
><sirlan...@hotmail.com> wrote in message
>>Can anyone offer some explaination?
>
>The word is EXPLANATION, you idiot!
>>
In like vein it's 'we just felt our way through the takeoff ROLL', you idiot!.
If you can't figure this out then ask and I'll type slowly using little letters
for you sir.
sddso
Bill Kambic wrote:
>
/snip/
> This is an interesting question. Could one of our Across the Pond
> participants tell us why British engines go backwards!<g> (Other than it is a
> continuation of other backwards tendencies, like driving on the wrong side of
> the road.<g>)
>
> Bill Kambic, Bright Star Farm, Kingston, TN
> http://www.geocities.com/Heartland/Hills/1816
> Mangalarga Marchador: Style, Stamina, Symmetry, Smoothness
Early on, British engines weren't the only ones. WWI-vintage photos of
SPAD XIIIs (powered by liquid-cooled Hispano-Suiza engines) show a prop
pitch indicating clockwise rotation--the blade on the right side had its
upward edge facing forward. And the negatives weren't reversed (all too
frequent these days): numerals and letters painted on the cloth skin
read OK.
Dudley Henriques
"Gord Beaman" <gbe...@pei.sympatico.ca> wrote in message
news:3a567f05...@news1.pei.sympatico.ca...
In high performance fighters, the short field takeoff was a little different
than this procedure. The Mustang for example, could jump wheel chocks at 40
inches. It was a beast to hold brakes at high power settings. The best
procedure I found for short fields was to preset about six degrees right
rudder trim, use 20 degrees of flap, hold brakes and advance power to about
40 inches, releasing the brakes at 35 inches. You kept the tail down[locked
the tail wheel] and smoothly went to 61 inches at 3000rpm. You flew it off
at 100 indicated and cleaned up the gear fast, keeping the flaps at 20 and
the IAS at between 95 and 100 indicated. After reaching a safe altitude you
cleaned up the flaps and climbed out at about 170 indicated.
Using this procedure, I could usually rotate the 51 in less than 1000 feet.
Bill Horne
before the rudder became effective. Since there were no brakes
(seaplane), pilot technique was to control the yaw by leading the power
application on the port engine. You sort of pushed the port throttle up
with your thumb while you dragged the starboard one along with your
pinkie, and then married them up as the rudder took hold. The co-pilot
then took over the throttles and set them at the max for takeoff. Of
course, all this was done concurrently with leveling the wings and
getting onto the step.
It seems that controlling yaw with differential power might work in most
multi's as long as the pilot has some throttles. It might be more
difficult with four engines.
Bill Horne
Bill Horne
"Counter-rotating" is an expression usually applied to highpowered
engine-prop combinations which actually have a double propeller on a
single axis, with each turning in opposite directions.
To answer your question, consider the P-38 in the case of an engine
failure. If the left engine fails, the prop is feathered and the
airplane continues on the right engine. Depending on the flight
conditions, it is likely that power will be added on the remaining
engine. Since the engine is not on the aircraft centerline, it will have
a tendency to cause the aircraft to yaw toward the dead engine. Rudder
is used to counteract the yaw. The effectiveness of the rudder varies
with the size and configuration of the rudder and the direction of
rotation of the prop ahead of it.
If the right prop has CW rotation (viewed from behind), then the airflow
around the tail boom will move in a CW swirl around the tail boom and
impinge on the rudder on the left side. This will aggravate the left yaw
tendency when flying on only the right engine. In addition, at high
angles of attack, the down-moving prop blade creates more thrust than
the up-moving blade, adding to the left yawing tendency. The conclusion
is that the right prop should turn CCW, so that the prop swirl and
down-moving blade forces would tend to counter the yawing caused by the
prop being off the airplane center line. Turn every thing around and the
left prop should turn CW.
That's the theory. As I recall, it was intended that the P-38 props be
left-CW and right-CCW, but early tests showed some undesirable noise or
airflow problems with the down-moving blades near the cockpit module, so
the final configuration was left-CCW and right-CW. I can't cite any
references for this. Perhaps someone else can varify or refute this
part.
In my experience, I have flown four different twin engine aircraft.
While none of these had a power to weight ratio anywhere near that of
the P-38, none had opposite rotating props. All had the same
engine/prop(CW) setup on both sides, and we did not normally worry about
one side more than the other. However, I had a few hours in the S-2
while I was a flight student in 1958. It had relatively high powered
engines on a short coupled airframe. I recall that a port (left) engine
failure was harder to handle at low speed. The S-2 had an emergency
rudder boost, but we were not allowed to use it for simulated failures,
since the boost system itself had a history of failing and compounding
the emergency.
Bill Horne
C.C.Jordan
> However, I had a few hours in the S-2
>while I was a flight student in 1958. It had relatively high powered
>engines on a short coupled airframe. I recall that a port (left) engine
>failure was harder to handle at low speed. The S-2 had an emergency
>rudder boost, but we were not allowed to use it for simulated failures,
>since the boost system itself had a history of failing and compounding
>the emergency.
I should explain that the S-2/C-1 had a multiple segment rudder assembly.
When you selected rudder assist, or boost, both the normal rudder and the
equally large hydraulically boosted segment were activated. This not only
provided for a powered rudder with doubled area, but increased displacement
by about 10-15 degrees (I don't recall the specific angle).
Back in 1977, I was doing a maintenance turn-up on a C-1A. I
watched the plane captain as he ran me through a controls check.
When he signaled for rudder boost, I flipped on the boost switch and
kicked full left rudder. When I went to center the pedals, the boosted
segment remained hard left. The cylinder had stuck fast. Had this happened
in flight, it would have been an adventure, to say the least.
Fortunately, that was the only time I ever saw that failure. The biggest
hassle with S-2/C-1 hydraulics was with the wingfold system. That
could be a nightmare.
Dale
wrote:
The B-17 throttles are set up so it's fairly easy to manipulate them for
differential power...and in fact that is the most powerful method to maintain
directional control early in the takeoff roll.
> It seems that controlling yaw with differential power might work in most
> multi's as long as the pilot has some throttles. It might be more
> difficult with four engines.
--
Dale L. Falk
Cessna 182A
N5912B
There is nothing - absolutely nothing - half so much worth doing
as simply messing around with airplanes.
http://home.gci.net/~sncdfalk/flying.html
Dale
The B-17 will go off to the left also if you let it. We keep the tailwheel on
the ground until the rudder is effective, use differential power, rudder and if
needed you can steer with the ailerons (using adverse yaw).
> The Lancaster had a vicious swing to port at the start of the takeoff roll,
> required almost full right rudder to counteract it right at the beginning,
> then
> lesser and lesser amounts as the rudder became more effective.
--
Gord Beaman
>The P-5 tended to veer to port in the early part of the takeoff run
>before the rudder became effective. Since there were no brakes
>(seaplane), pilot technique was to control the yaw by leading the power
>application on the port engine. You sort of pushed the port throttle up
>with your thumb while you dragged the starboard one along with your
>pinkie, and then married them up as the rudder took hold. The co-pilot
>then took over the throttles and set them at the max for takeoff. Of
>course, all this was done concurrently with leveling the wings and
>getting onto the step.
>
>It seems that controlling yaw with differential power might work in most
>multi's as long as the pilot has some throttles. It might be more
>difficult with four engines.
>
>Bill Horne
>
Hi Bill,
The Argus had a little tendency yaw to port at the start of the run, especially
a 'max rate takeoff' but the nosewheel steering was very powerful and with the
minimum nosewheel load set at 10,000 pounds it wasn't hard to control at all.
Gord Beaman
Gord Beaman
Yes, I keep forgetting how much power fighters have in relation to their weight,
(that'd be interesting...what 'does' a P-51 weigh and what's the engine
power?). An Argus has roughly 9 pounds per HP. You can apply just under full wet
power on the brakes, it's not limited to a 'jumping the chocks' kind of thing
but the fact that at zero groundspeed you cannot get the RPM high enough to
avoid overtorqueing/overboosting the engines.
Cub driver
>"Counter-rotating" is an expression usually applied to highpowered
I think that's contra-rotating, at least in the USAAF/USAF. I'm
thinking of one version of the XB-35. Dunno if this is an iron-clad
distinction.
>engine-prop combinations which actually have a double propeller on a
>single axis, with each turning in opposite directions.
>
all the best - Dan Ford
Remains (a story of the Flying Tigers)
http://danford.net/remains.htm
C.C.Jordan
>
>>"Counter-rotating" is an expression usually applied to highpowered
>
>I think that's contra-rotating, at least in the USAAF/USAF. I'm
>thinking of one version of the XB-35. Dunno if this is an iron-clad
>distinction.
Yeah, I agree. Contra-rotating refers to two props turning in opposite
directions on a common shaft or axis and powered by a single engine
or power unit (coupled engines).
Examples: TU-95, TU-114, P-75A, and yes, the XB-35.
Counter-rotaing props refers to individual propellers rotating in opposite
directions on individual shafts, usually powered by individual engines, but
not necessarily along separate thrust lines. The Dornier Do X had linear
paired engines, with forward being a tractor, the rear being a pusher.
These engines were on the same thrust line. Another Dornier of interest
was the Do 335, which had a tractor and pusher powerplants on slightly
different thrust lines. Typically we think of counter-rotating props as being
configured like the P-38, F-82 or DeHavilland Hornet. Yet, there are many
possible configurations. The Wright Flyer used a single engine to power
two counter-rotating props on separate thrust lines via a chain drive.
Dudley Henriques
> "Dudley Henriques" <dhenr...@earthlink.net> wrote:
>
> >
> >"Gord Beaman" <gbe...@pei.sympatico.ca> wrote in message
> >news:3a567f05...@news1.pei.sympatico.ca...
> >> Jor...@worldwar2aviation.com (C.C.Jordan) wrote:
> >>
> >> >On Fri, 05 Jan 2001 00:31:15 GMT, Erik Shilling
> >> ><eri...@ix.netcom.com@ix.netcom.com> wrote:
> >> >
> >> >>In article <3a5502d8....@nntp.atl.mediaone.net>,
> >> >> sirlan...@hotmail.com wrote:
> Yes, I keep forgetting how much power fighters have in relation to their
weight,
> (that'd be interesting...what 'does' a P-51 weigh and what's the engine
> power?).
The 51 at airshow weight with half tanks came in at just about 9000 + lbs.
The Merlin developed about 1500 hp. The Hamilton Standard measured a little
over 11 ft. in dia. Just to give you some idea of how critical power
handling is in the 51, the total prop clearence if you horse the stick
forward on takeoff is only 7+ inches.
Dudley
Mac
>
>
> The 51 at airshow weight with half tanks came in at just about 9000 + lbs.
> The Merlin developed about 1500 hp. The Hamilton Standard measured a little
> over 11 ft. in dia. Just to give you some idea of how critical power
> handling is in the 51, the total prop clearence if you horse the stick
> forward on takeoff is only 7+ inches.
I always thought that up close these things looked more like helicopters
on their side;)
Dudley, I know there are many factors involved, but any idea how those
figures translate into a power to weight ratio, roughly?
Ta.
--
Mac.
Gord Beaman
Interesting!...that's 6 pounds per horsepower, as I said the Argus runs near
9lb/HP so that's a huge difference...be interesting to compare your 6lb/HP to
modern jets...I've been given to understand that pounds of thrust equates to HP,
is that correct do you think?. The AOI for the CC-109 Cosmo (Convair 580) called
it 600 pounds of residual thrust from the turboprop engines and said that was
about equal to 600 HP.
Peter Stickney
(Using # for thrust, and ft/sec for velocity.)
(Basically, 1 HP = 550# of force for 1 second. Yes, I know that
Pounds aren't mass.)
Something that produced constant power, like a recip or turboprop,
will produce a huge amount of thrust at low speeds, decreasing as the
speed increases. Basically, 1 HP = 1 pound of thrust at 375 mph, more
when slower than 375, and less above. This gets complicated by
factoring in propeller efficiency, which varies according to things
like Tip Sped and Advance Ratio. (The ratio of tip speed to forward speed.)
At high tip speeds, transonic effects also chime in.
At 0 airspeed, (static), it gets a bit complex as well.
The rule of thumb for determining Equivalent Shaft Horspower for a
Turboprop is ESHP = Shaft HP + (Jet thrust / 2.5). This is most
represenatatice of a static case. (Engine sitting still.)
Because a propeller can develop huge amounts of thrust at low speeds,
all sorts of interesting things can happen. Ed Rousa, in his book of
Skyraider experiences, mentions an airshow (Probably at Pax, but I
don't remember) in the early '60s that was to feature a low-speed
flyby by an AD Skyraider with the brand-new F4H Phantom. At the
midline, the F4H was to light the burners and rockdt away from the
creaking antique Spad. The AD pilot took umbridge at this, and when
he saw the F4Hs nozzles open for the AB light, shoved the R3350 on the
AD to War Emergency power. The AD kept up with the Phantom until well
past the end of the runway, out of sight of the crowd. The comments
of the F4H Project Office were not recorded.
--
Pete Stickney
sddso
Gord Beaman wrote:
>
> sddso <jsp...@dtgnet.com> wrote:
>
/snip/
> >
> >Early on, British engines weren't the only ones. WWI-vintage photos of
> >SPAD XIIIs (powered by liquid-cooled Hispano-Suiza engines) show a prop
> >pitch indicating clockwise rotation--the blade on the right side had its
> >upward edge facing forward. And the negatives weren't reversed (all too
> >frequent these days): numerals and letters painted on the cloth skin
> >read OK.
>
> But wouldn't that indicate a CCW rotation?...
>
> --
> Gord Beaman
> PEI Canada.
This is one of several reasons I'm not allowed out in public without
adult supervision.
On page 63 of James Gilbert's _The Great Planes_ (New York: Grosset &
Dunlap, 1970, LCCN 70-117510), at the bottom, there is a photo of a SPAD
XIII. The *left* blade (in relation to the airframe) has its forward
edge downward. The view is of the aircraft's left front quarter,
placing the left blade to the right in the photo. This would be CCW
rotation as viewed from the cockpit. Don't most US piston engines make
the right hand blade (on two-blade installations) turn downward?
Eddie Rickenbacker has his muddy left foot (in either leather puttees
or near-knee-high boots) on the left main wheel, toe pointing right. He
looks as if he's leaning against the left prop blade; if the engine
burped in its proper direction, the prop would swing out from under him
rather than hitting him in the butt. His big white "1" is readable on
the fuselage flank and the black "S" (with small XIII above it) and a
few digits are readable against the tricolor on the rudder, on the
aircraft's own left side.
Gord Beaman
--cut--
Most interesting Peter, thanks, I love your last sentence above, said report was
likely quite unreadable, probably consisting of many strings like !@#$%^&*().
:).
BTW, I wonder what the Skyraider weighed?...I'll bet it's 'weight to HP ratio'
would be interesting!...
Gord Beaman
>
>
>Gord Beaman wrote:
>>
>> sddso <jsp...@dtgnet.com> wrote:
>>
>/snip/
>> >
>> >Early on, British engines weren't the only ones. WWI-vintage photos of
>> >SPAD XIIIs (powered by liquid-cooled Hispano-Suiza engines) show a prop
>> >pitch indicating clockwise rotation--the blade on the right side had its
>> >upward edge facing forward. And the negatives weren't reversed (all too
>> >frequent these days): numerals and letters painted on the cloth skin
>> >read OK.
>>
>> But wouldn't that indicate a CCW rotation?...
>>
>> --
>> Gord Beaman
>> PEI Canada.
>
>This is one of several reasons I'm not allowed out in public without
>adult supervision.
>
So you say, but if the truth were known, it's my bet that you were just testing
to see if we were paying attention!... :)
Peter Twydell
<jw...@columbia.edu> writes
>>All American props, with the exception of one of the P-38's, rotate
>>clockwise when viewed from the rear. It had been my understanding
>>that British props rotated counter-clockwise. Heard of some stories
>>of uninformed American pilots, flying British planes for the first
>>time, automatically applying the wrong rudder on takeoff and going off
>>observed some British props rotating clockwise and other
>>counter-clockwise. Can anyone offer some explaination?
>
>>Mel Shettle
>
>Bristol radial engines had props that rotated counter-clockwise, while
>British in-line engines, such as the Merlin, rotated clockwise. I have
>no idea of the reason for this, but one consequence was that Lancaster
>IIs (Bristol Hercules powered), and Beaufighter Mk IIs (Merlin powered),
>had props that rotated in a different direction from all other marks.
>
>Jim Erickson
But the R-R Griffon rotated anti-clockwise, except for those with
contraprops, of course. Direction of prop rotation depended on the
reduction gear setup, but what was the direction of crankshaft rotation
for any of these engines? And what about Napier's H engines, such as the
Sabre? Did the crankshafts rotate in the same direction or not? Has
anyone got a recording of a Sabre?
The answers to these questions and more in the next episode... Sorry,
that's the _Soap_ NG.
--
Peter
TSuglio
>>>clockwise when viewed from the rear. It had been my understanding
This is true if you are talking of recipricating engines. If you were including
turboprops, the OV-10 and Mohawks had opposing rotation. There may be
othersthat I am not aware of.
Cheers,
TTTW
Steven P. McNicoll
"TSuglio" <tsu...@aol.com> wrote in message
news:20010212203832...@ng-fa1.aol.com...
>
> This is true if you are talking of recipricating engines.
>
No it isn't.
TSuglio
>>
>
>No it isn't.
>
No what isn't? The P-38s #1 prop turned counterclockwise as viewed from the
rear of the aircraft.
Steven P. McNicoll
>
> No what isn't?
>
It isn't true that all American props, with the exception of one of the
John Randolph
you are contradicting Tom?
"Steven P. McNicoll" <ronca...@writeme.com> wrote in message
news:t8i8b2p...@corp.supernews.com...
VEWenneker
> P-38's, rotate
> clockwise when viewed from the rear. >>
I thought all aircraft with two propeller driven engines had one counter
rotating engine, ie., one clockwise and the other counter-clockwise in order to
balance the lift generated over each wing. Is this right? Or wrong?
Laurence Doering
Wrong. Most multiengine propeller-driven aircraft have all the
props rotating the same way, regardless of which wing they're on.
There is an advantage to having counter-rotating props -- when both
engines are running, torque and P-factor cancel each other out,
so there's no yawing tendency to counteract with power changes.
Also, twins with counter-rotating props don't have a "critical
engine" -- you're equally badly off regardless of which engine
fails.
Without counterrotating props, it would be worse to have
the left engine fail (on most twins) because the yawing tendency
due to torque and P-factor would be to the left, the same direction
as the yaw tendency caused by the asymmetrical thrust from the
right engine. This means you need more rudder to counteract
the yaw and fly straight on one engine, and the minimum speed
at which you can fly successfully (Vmc, the minimum speed at
which the fully deflected rudder provides enough force to
counteract the yaw) is higher.
The disadvantage of counterrotating props is that you
need some way to make the props rotate in different
directions. If the engines are connected to the props
through reduction gears, you need different gearing
for the left and right sides. If not (if the props are
bolted to the engine crankshaft, like on many light twins)
you need different models of engine that rotate in opposite
directions.
Usually the mechanical simplicity and reduced weight
that comes from having an identical engine/propeller
combination attached to each engine mount wins over the
slight safety advantage of counterrotating props.
ljd
Bill Shatzer
Generally "handed" engines were considered worthwhile only on fighters
which need neutral roll characteristics in both directions.
The issue is not lift (which would be identical regardless of prop
rotation) but the torque generated by the engines and its effect on roll
rates. Opposite rotating engines would cancel the torque and provide
identical roll rates in both directions.
With bombers and transports and the like which are not usually
called upon to make extreme roll manuvers, "handed" engines were
generally thought an unnecessary complication. Right off hand, I can't
think of a WW2-type twin engined bomber a/c which used "handed" engines.
Pro'ally was one or two but darned if I can think of one.
Cheers and all,
TSuglio
>rotating engine, ie., one clockwise and the other counter-clockwise in order
>to
>balance the lift generated over each wing. Is this right? Or wrong?
It is wrong. Every twin engined military aircraft I worked on, both engines
props turned in the same direction, those include P2V, S2F, HU-16, R4D, P5M,
SNB, T-29 and C-119.
Cheers,
TTTW
TSuglio
of P-factor and torque, prop wash. The AD vertical fin was built a few degrees
left of center to counter Prop wash, torque. And the S2F had an alternate
rudder in case of engine failure. If you look at a picture of the S2F tail
section, you will see that it appears that there is a rudder within a rudder.
Normal operation was just the last segment of rudder working, but with
alternate rudder switch on, both segments worked giving the aircraft much more
rudder authority.
Cheers,
TTTW
TSuglio
>called upon to make extreme roll manuvers, "handed" engines were
>generally thought an unnecessary complication. Right off hand, I can't
>think of a WW2-type twin engined bomber a/c which used "handed" engines.
>
>Pro'ally was one or two but darned if I can think of one.
>
>Cheers and all,
>
I worked the Navy JD (B-26) and both engines rotated same direction. I am 99%
sure the B-25 was the same. If no one knows for sure about the P-60, I'll run
over to the museum and take a look at it.
Cheers,
TTTW
QDurham
>This brings to mind two Navy birds I worked on that had unique features
because of P-factor and torque, prop wash. The AD vertical fin was built a few
degrees left of center to counter Prop wash, torque.>
Very common on all planes -- including the SNJ and sundry Cessnas. Vertical
fin lined up so as to be least draggy at cruise.
Quent
Jonathan Stone
Bill Shatzer <bsha...@OregonVOS.net> wrote:
>Generally "handed" engines were considered worthwhile only on fighters
>which need neutral roll characteristics in both directions.
>
>The issue is not lift (which would be identical regardless of prop
>rotation) but the torque generated by the engines and its effect on roll
>rates. Opposite rotating engines would cancel the torque and provide
>identical roll rates in both directions.
>
>With bombers and transports and the like which are not usually
>called upon to make extreme roll manuvers, "handed" engines were
>generally thought an unnecessary complication. Right off hand, I can't
>think of a WW2-type twin engined bomber a/c which used "handed" engines.
Some later marques of Mosquito had handed engines; the late
nightfighters, (NF30) but I recall seeing a source which says a bomber
variant had handed engines, too. (Perhap the imperial war museum site?)
Bill Shatzer
On 14 Feb 2001, TSuglio wrote:
> The USA only had three WWII twin engined bombers correct? B-25, B-26, and
> P-60.
The P-60 was, according to my fragmentary references, a single-engined
P-40 development with only five built. Perhaps you meant P-70 which was a
nightfighter development of the A-20 Havoc?
But, the US had a few more than just three twin-engined bombers. The B-18
and B-23 were used in considerable numbers early on (although not
overseas) and the A-26 entered into front line service in the ETO
commencing in 1944.
The USN operated considerable numbers of PV-1 Venturas and PV-2 Harpoons
as well while both the USAAF and the USN operated twin-engined Hudsons
under the designations A-28/29 and PBO-1 respectively.
Cheers and all,
Mortimer Schnerd, RN
"Jonathan Stone" <jona...@DSG.Stanford.EDU> wrote in message
news:96d3d9$c6r$1...@nntp.Stanford.EDU...
> >Generally "handed" engines were considered worthwhile only on fighters
> >which need neutral roll characteristics in both directions.
>
> nightfighters, (NF30) but I recall seeing a source which says a bomber
> variant had handed engines, too. (Perhap the imperial war museum site?)
While not a bomber, the P-38 Lightning had counter rotating props.
--
Mortimer Schnerd, RN
msch...@carolina.rr.com.nospam
http://home.carolina.rr.com
Quote of the Day: "I voted Republican this time around. The Democrats left a
bad taste in my mouth"
- Monica Lewinsky
Steven P. McNicoll
"John Randolph" <REMOVEjr...@home.com> wrote in message
news:jvdi6.13465$Xj4.7...@news1.rdc1.sdca.home.com...
>
> If that's so, and I could care less, then why not be civil and explain why
> you are contradicting Tom?
>
It is so, I was civil, and I did not respond to any message in this thread
posted by anyone identified as Tom.
TSuglio stated that all American propellers driven by reciprocating engines,
with the exception of the P-38, rotated clockwise when viewed from the rear.
That's true for the vast majority, but there are many exceptions, beginning
with the Wright Flyer.
Steven P. McNicoll
"VEWenneker" <vewen...@aol.com> wrote in message
news:20010213173838...@ng-fi1.aol.com...
>
> I thought all aircraft with two propeller driven engines had one
> counter rotating engine, ie., one clockwise and the other
> counter-clockwise in order to balance the lift generated over
> each wing. Is this right? Or wrong?
>
It's wrong. Some are that way, but most multiengine aircraft have the
propellers turning in the same direction.
Steven P. McNicoll
"Bill Shatzer" <bsha...@OregonVOS.net> wrote in message
news:Pine.SUN.3.96.101021...@compass.oregonvos.net...
>
> The issue is not lift (which would be identical regardless of
> prop rotation) but the torque generated by the engines and
> its effect on roll rates.
>
That's not quite correct, the rotation direction can affect lift. The North
American F-82 Twin Mustang was designed with the propellers turning
in at the bottom, the blades in front of the wing center section were
moving upward. This apparently put the center section in a permanently
stalled condition and the aircraft could get airborne only at light weight
and high speed. The engines and propellers were swapped and the
problem was solved.
Dudley Henriques
You are not civil. You are curt, rude, and pedantic through inference. You
constantly post single word or sentence "corrections" without proper
explanation. The effect of this is to belittle the opinion of someone else,
while at the same time showing complete disdain. In many instances you are
totally wrong.
Tom was speaking to a period of time and a class of aircraft well beyond the
Wright flyer. If you think he's mistaken, say so, but try a little
friendlier approach.
The following response,
> This is true if you are talking of reciprocating engines.
>
"No it isn't".
....just doesn't quite cut it on a newsgroup where people at least try to
discuss issues in a civil manner.
--
Dudley A. Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI/Retired
Steven P. McNicoll
>
> The USA only had three WWII twin engined bombers correct?
>
Incorrect, the actual number depends on a couple of things. By "USA" did
you mean United States of America or US Army? By "twin engined bombers" did
you mean twin-engined aircraft with a "B" for bomber designation or any twin
used for delivering bombs?
>
> B-25, B-26, and P-60.
>
The P-60 was not a bomber, it was a proposed fighter. I believe five were
built, none saw service.
>
> I worked the Navy JD (B-26) and both engines rotated same direction.
> I am 99% sure the B-25 was the same.
>
The Navy operated the B-26 as the JM, not JD. Navy B-25s were designated
PBJ.
>
> If no one knows for sure about the P-60, I'll run over to the museum
> and take a look at it.
>
What Museum? I wasn't aware that any P-60s survived. When you run over to
the museum, you'll find it to be a single engine aircraft.
Steven P. McNicoll
"Dudley Henriques" <dhenr...@earthlink.net> wrote in message
news:Cpxi6.1520$wb6.1...@newsread1.prod.itd.earthlink.net...
>
> You are not civil. You are curt, rude, and pedantic through inference.
>
You're mistaken, I am none of those.
>
> You constantly post single word or sentence "corrections" without proper
> explanation.
>
Yes, I do that, but I do so only rarely.
>
> The effect of this is to belittle the opinion of someone else,
> while at the same time showing complete disdain.
>
We're not discussing a matter of opinion here.
>
> In many instances you are totally wrong.
>
Cite one.
>
> Tom was speaking to a period of time and a class of aircraft well beyond
the
> Wright flyer.
>
No he wasn't, he was speaking about all american aircraft with reciprocating
engines.
>
> If you think he's mistaken, say so, but try a little friendlier approach.
>
That's good advice, you should heed it yourself.
>
> The following response,
> > This is true if you are talking of reciprocating engines.
> >
> "No it isn't".
>
> ....just doesn't quite cut it on a newsgroup where people at least try to
> discuss issues in a civil manner.
>
That's your opinion, I consider it short and to the point. That TSuglio's
post was in error is obvious to anyone with any knowledge of aviation
history.
Red Baron
engines used different directions of rotation?
/Red B.
TSuglio
never even thought once about the Wright Flyer or anything else up to WW II. I
worked on several WW II era (twin and multi- engined) and none of them had
"Handed" engines or props. I cannot explain aerodynamically why the P-38
required it, but I can tell you thatone very large reason for not having
"handed" engines is because, it would require very strong attention to detail
when it came to engine and prop changes. It would have created a real Murphey
problem. As a military aircraft mechanic for all of my adult life, I can tell
you that a mechanic can fuck-up a steel ball in a sawdust pit, so I can with
100% confidence tell you that the mechanics would have killed a hell of a lot
more airman then they did. Wrong engines props in the wrong position.
Cheers,
TOM
Dave Holford
"I'm right and you're wrong, always"
So there!!
Dave Holford
(I used to be one of those but have partly grown out of it now that I am
no longer an operational Air Traffic Controller - but it does take
time).
Lynn Coffelt
"TSuglio" wrote:
>As a military aircraft mechanic for all of my adult life, I can tell
> you that a mechanic can fuck-up a steel ball in a sawdust pit, so I can
with
> 100% confidence tell you that the mechanics would have killed a hell of a
lot
> more airman then they did. Wrong engines props in the wrong position.
> Cheers,
> TOM
(off topic a little, sorry)
OUCH!!!!! Valentines to you, too!
As a "military aircraft mechanic" (Aircraft Maintenance Technician,
actually) for
a few years myself, I cannot help but yelp!
I assure you that those who could "XXXX-up a steel ball", as you say,
were NOT mechanics. Of course there were some out there, hired as mechanics
who never mastered the art.
Some of the finest, most honest and trustworth REAL mechanics I've had the
pleasure to work with were "military". (take me, for instance) (grin)
Old Chief Lynn
Gord Beaman
--cut--
> As a military aircraft mechanic for all of my adult life, I can tell
>you that a mechanic can fuck-up a steel ball in a sawdust pit, so I can with
>100% confidence tell you that the mechanics would have killed a hell of a lot
>more airman then they did. Wrong engines props in the wrong position.
>Cheers,
> TOM
Doesn't sound too likely to me Tom, hell, if it's even 'possible' to
'install' a 'wrong handed' prop, which I doubt, anyway do you really
suppose any pilot or F/E wouldn't notice it during their
walkaround?...lordy, even if they got 'that' far, then it'd sure as
hell be pretty evident when they started to taxi. I can't even imagine
'attempting' to take off...where's this 'danger' that you speak of?.
TSuglio
>> I am 99% sure the B-25 was the same.
>>
>
>The Navy operated the B-26 as the JM, not JD. Navy B-25s were designated
>PBJ.
>
I beg to differ with you, as the Navy did operate B-26 as the JD. There were
many of them in the VU squadrons at North Island and they dragged targets for
ships to shoot at and they also carried drones.
TSuglio
>actually) for
>a few years myself, I cannot help but yelp!
>
>I assure you that those who could "XXXX-up a steel ball", as you say,
>were NOT mechanics. Of course there were some out there, hired as mechanics
>who never mastered the art.
>
>Some of the finest, most honest and trustworth REAL mechanics I've had the
>pleasure to work with were "military". (take me, for instance) (grin)
>
>Old Chief Lynn
>
about you to be absolutely true.1You did not go into the service as a Chief
and, 2 you had to have been a rookie (3level) aircraft mechanic once. Am I
right so far?
All kidding aside, when I said that about the saw dust pit, it only means that
as an aircraft maintenance technician, you have to be on top of it at all times
or Murphey will jump up and bite you on the ass. Having handed engines props
would have meant things like ordering the wrong engine prop etc. not to mention
getiing wrong position installed on the plane.
One of the drivers said it would be caught on walkaround, yeah I believe that.
If it would be caught on walkaround (pre-flight), then we would not have a
history of aircraft taking off with their wings folded, or empty fuel tanks,
and many other scenerios that have taken place.
Cheers,
Tom
TSuglio
>'install' a 'wrong handed' prop, which I doubt, anyway do you really
>suppose any pilot or F/E wouldn't notice it during their
>walkaround?...lordy, even if they got 'that' far, then it'd sure as
>hell be pretty evident when they started to taxi. I can't even imagine
>'attempting' to take off...where's this 'danger' that you speak of?.
>
was shooting touch and gos when someone noticed a big black patch on the bottom
of the right wing. They told the aircraft to make a full stop landing next
goaround so the SOF could take a look. Low and behold, he discovered a 4 foot
lower wing panel missing. 781A showed that panel removed on a red X for repair
in the sheet metal shop. So much for FE and rthe rest of the aircrew doing a
walkaround. And yes, you can get the props in the wrong position.
Cheers,
Tom
TSuglio
>P-40 development with only five built. Perhaps you meant P-70 which was a
>nightfighter development of the A-20 Havoc?
I stand corrected. The aircraft I was thinking of is the P-61 Black Widow. That
is the one I meant I would run over to the Museum to look at and see if it had
handed engines.
Cheers,
Tom
JDupre5762
I recently did an inspection of a light twin. It did not have "handed" engines
but the log books showed certain serial number engines in the left and right
hand sides. When I actually checked the serial numbers on the engines as
installed they were reversed. So the logbook entry for the LH engine showing
that "this engine installed in LH position...." was wrong.
Not a big deal as it didn't matter which engine was where but the engines were
installed 5 years ago! Murphy said it best...
John Dupre'
OXMORON1
>>PBJ.
Two different B-26 a/c.
Martin B-26 used by the Navy as JM
Douglas A/B-26 used by the Navy as JD
Different manufacturers, different airplanes caught in the reivsed nomenclature
game.
Oxmoron1
Gord Beaman
--cut--
> So much for FE and rthe rest of the aircrew doing a
>walkaround.
Well, seems like a pretty sloppy external check (walkaround) to miss
something this big, also how did they miss the 781A entry?...good
god...
> And yes, you can get the props in the wrong position.
> Cheers,
> Tom
This one I have trouble with Tom, I can see (barely) getting an engine
AND it's prop installed on the wrong side (you said that it's
physically possible).
But...BUT...if you put a 'left hand tractor prop' on a 'right hand
turning engine' then the prop will be turning BACKWARDS!...it won't be
REAL EFFICIENT like that Tom, it'll give *really* piss-poor takeoff
performance :) ...want to rethink this again?...standing by
sir......... :)
PosterBoy
P-60?
Perhaps you mean P-61, The Black Widow? A twin-engine fighter, however,
not a bomber.
Or C-60, the Lockheed Lodestar? A transport, however.
Or A-20, perhaps? Or its sorta-successor, the A-26?
Or........perhaps some aircraft fueled by B-60 bio-diesel fuel (OXy G
B-60)???
Cheers.
Steven P. McNicoll
>
> I beg to differ with you, as the Navy did operate B-26 as the JD. There
> were many of them in the VU squadrons at North Island and they
> dragged targets for ships to shoot at and they also carried drones.
>
You're confusing aircraft, eras, or both. You wrote; "The USA only had
three
WWII twin engined bombers correct? B-25, B-26, and P-60." The B-26 of
World War II was the Martin B-26 Marauder, the Navy operated it as the JM.
The USAAF's Douglas A-26 Invader was operated by the Navy as the JD.
A few years after the war the "A" designation was dropped. The Douglas
A-26 was redesignated B-26, the Martin B-26 was already out of the
inventory.
JDupre5762
Douglas B-18 Bolo
Douglas B-23 Dragon
Douglas A-20 Havoc
Douglas A-26 Invader
North American B-25 Mitchell
Lockheed B-34 Ventura
Martin B-26 Marauder
Also Lockheed built the Hudson and Martin built the Maryland and Baltimore
which probably had B designations but weren't really used by the USAAF.
John Dupre'
Mary Shafer
>> I thought all aircraft with two propeller driven engines had one
>> counter rotating engine, ie., one clockwise and the other
>> counter-clockwise in order to balance the lift generated over each
>> wing. Is this right? Or wrong?
> When I said all American planes, I guess that was all too
> encompasing and I never even thought once about the Wright Flyer or
> anything else up to WW II.
You didn't think of the Wright Flyer as being an aircraft with two
propellor driven engines, one counter-rotating, because it only had
one engine. Two propellors, which may have rotated in opposite
directions because of the way they took power off the engine, but only
one engine.
--
Mary Shafer Senior Handling Qualities Research Engineer
sha...@orville.dfrc.nasa.gov
NASA Dryden Flight Research Center, Edwards, CA
Of course I don't speak for NASA
Al Bowers
> >> I thought all aircraft with two propeller driven engines had one
> >> counter rotating engine, ie., one clockwise and the other
> >> counter-clockwise in order to balance the lift generated over each
> >> wing. Is this right? Or wrong?
> > When I said all American planes, I guess that was all too
> > encompasing and I never even thought once about the Wright Flyer or
> > anything else up to WW II.
> You didn't think of the Wright Flyer as being an aircraft with two
> propellor driven engines, one counter-rotating, because it only had
> one engine. Two propellors, which may have rotated in opposite
> directions because of the way they took power off the engine, but only
> one engine.
The Wright Flyers did, indeed, have counter-rotating props. The chain
drive to the left prop had a twist in it so that it would rotate
opposite of the engine and right prop.
Al Bowers
--
Al Bowers
bow...@orville.dfrc.nasa.gov
Gord Beaman
"Propeller driven engines"...my! my!...what *will* they invent next?.
Could 'P sub s' have played any part in their development
perchance?...
Dudley Henriques
"Gord Beaman" <gbe...@pei.sympatico.ca> wrote in message
> "Propeller driven engines"...my! my!...what *will* they invent next?.
>
> Could 'P sub s' have played any part in their development
> perchance?...
Not according to my wife!!! She says that Ps relates only to my present
energy state which she also hastens to add is "not so steady state".
Apparently, at my tender age, what happens is that when I get up and begin
walking across the room; thrust immediately equals drag and presto!!!!
.....Ps=0. :-)
Dudley
Steven P. McNicoll
>
> When I said all American planes, I guess that was all too encompasing
> and I never even thought once about the Wright Flyer or anything else
> up to WW II.
>
There have been a fair number since WWII. The North American F-82 Twin
Mustang had counter rotating propellers. So did some Piper Twin Comanches
and Navajos. Most pusher aircraft had propellers that rotated
counterclockwise when viewed from the rear. The Convair B-36 had six of
them. Other examples are the Lake amphibians, Cessna Skymaster, Republic
Seabee, etc. Many homebuilt airplanes that used automobile engines had
propellers that rotated "backwards".
Steven P. McNicoll
"JDupre5762" <jdupr...@aol.com> wrote in message
news:20010215125823...@ng-fz1.aol.com...
>
> Douglas B-18 Bolo
> Douglas B-23 Dragon
> Douglas A-20 Havoc
> Douglas A-26 Invader
> North American B-25 Mitchell
> Lockheed B-34 Ventura
> Martin B-26 Marauder
>
> Also Lockheed built the Hudson and Martin built the Maryland and Baltimore
> which probably had B designations but weren't really used by the USAAF.
>
The Martin Maryland was designated XA-22 by the USAAC, it was evaluated but
not purchased for service with US forces. The Martin Baltimore was
designated A-23 and A-30 by the USAAF. They never operated the A-23, but
did operate some A-30s in non-combat duties.
Steven P. McNicoll
"Mary Shafer" <sha...@orville.dfrc.nasa.gov> wrote in message
news:u066ibu...@orville.dfrc.nasa.gov...
>
> You didn't think of the Wright Flyer as being an aircraft with two
> propellor driven engines, one counter-rotating, because it only had
> one engine. Two propellors, which may have rotated in opposite
> directions because of the way they took power off the engine, but only
> one engine.
>
Two propeller driven engines? Only one of the propellers was
counter-rotating?
The propellers on the Wright Flyer were chain driven. One of the chains, I
believe the left one, formed a figure eight which caused that propeller to
turn in the opposite direction.
Frank May
Mohawk's weren't.
sddso
A booklet on aircraft in the Air Force Museum collection shows a photo
of a P-61C (page 60). Both props appear to rotate clockwise when viewed
from behind. I'd give the bibliographic citation but the booklet has no
copyright nor publishing information, except to say it was distributed
by the Air Force Museum Foundation, Inc.
The P-61 was a night interceptor, the first US warplane specifically
designed for airborne radar, with a span of 66 feet and a gross weight
of 35,855 pounds (note that max weight of the original DC-3 was only
some 21,000 pounds). As such, twist-turn-jink was probably a smaller
part of its repertoire than a stereotypical fighter. Therefore, the
disparate impact on roll rate from two props turning in the same
direction may have been less important. The only thing the P-61 shared
with the P-38 was the general planform of twin booms and central-pod
fuselage.
The same booklet shows a photo of an F-82B on page 66. It appears that
the starboard engine turns counterclockwise when viewed from behind, and
the port engine turns clockwise when viewed the same way.
TSuglio
>something this big, also how did they miss the 781A entry?...good
>god...
Well, Your right. There were a whole bunch of people that got into a lot of
trouble , starting with the Crew Chief and working up from there. Someone
signed off the exceptional release without getting out of the truck and looking
the plane over. The F/E had his head up his ass and the right seater never
bothered to check anything out. Other than that is was a great day.
>This one I have trouble with Tom, I can see (barely) getting an engine
>AND it's prop installed on the wrong side (you said that it's
>physically possible).
>
>But...BUT...if you put a 'left hand tractor prop' on a 'right hand
>turning engine' then the prop will be turning BACKWARDS!...it won't be
>REAL EFFICIENT like that Tom, it'll give *really* piss-poor takeoff
>performance :) ...want to rethink this again?...standing by
>sir......... :)
>
One of the benefits of not having handed engines is that you can install the
engine in any position on a twin or multi engined plane. If you do have handed
engines, it is entirely possible to get the wrong engine on the wrong position.
All as it takes is one person not paying attention.
The onlyn difference between handed props is the blades are basically mounted
backwards, so the leading edge is facing the other direction on one of the prop
hubs. The hubs remain the same because the engine turnes in the other
direction, and the props are mounted to the crankshaft which is just a splined
shaft to fit the splines in the prop hub. Of course there is a little more to
it than that, like shims, governors, oil ports, pitch control, etc.
So actually, if you really want to get very technical, props on the front of
the wing are also pushers just like a B-36. Why? because after you get the prop
installed on the crankshaft, you install a very large retaining nut which is
what the prop pushes against.
Cheers,
Tom
TSuglio
>energy state which she also hastens to add is "not so steady state".
>Apparently, at my tender age, what happens is that when I get up and begin
>walking across the room; thrust immediately equals drag and presto!!!!
>.....Ps=0. :-)
>
>Dudley
Dudley, You too?
Tom
Gord Beaman
Har!...sounds vaguely familiar to me too Dudley!...Of course I
shouldn't take your ...'walking across the room'... too literally,
right?. :)
Also the above post is merely another in the small series of jabs that
seems to have evolved between Mary and myself. We seem not to get
along too well, just one of those 'personality clash' things I guess.
Ken Sykes
>
> While the OV-10 Bronco props were indeed counter rotating, but the OV-1
> Mohawk's weren't.
I've flown in both, but darned if I can remember which way
the props spun. Now I'll have to dig out my slides and
look at the pitch angles. Don't anyone wait on this, it might
take months...
Tallyho!
KS
TSuglio
days. I live about 4 miles from the Air Force Museum and rather than try to
rely on memory for a lot of these issues, I offer me to go over to the museum
and check it out. They have a wonderful research department, and a fantastic
book store.
At your requests, I will gladley go over and find out "from the horses mouth"
sort of speak everything I can for you. And if you are looking for a certain
book or books on a particular aircraft, they probably have it. Plus, I have
been into their files and they have thousands of photos that have never been
seen publicly. They charge a fee for the photos to be duplicated. I am not
trying to sell the museum, just offering to help if someone needs it.
This offer arises from this counterotating engine, props thread. Why not go
get the diffinitive answer?
Cheers,
Tom
Dudley Henriques
> "Dudley Henriques" <dhenr...@earthlink.net> wrote:
>
> >
> >"Gord Beaman" <gbe...@pei.sympatico.ca> wrote in message
> Also the above post is merely another in the small series of jabs that
> seems to have evolved between Mary and myself. We seem not to get
> along too well, just one of those 'personality clash' things I guess.
Mary, like most engineers at her level, has a tendency to present things
analytically at times. I like her very much. Through the years we have
exchanged some personal thoughts as well. I've always found her information
to be completely compatible with my experience.
Always Remember Gord;
The optimist says,
" The bottle is half full".
The pessimist says,
"The bottle is half empty"
The Engineer will say,
"This damn bottle is twice as big as it has to be!!!!!. Call those idiots
over at management and tell them if they keep wasting the company's money
this way we're all going to end up in the poorhouse".
:-)
--
Dudley A. Henriques
International Fighter Pilots Fellowship
Commercial Pilot/CFI/Retired
Gord Beaman
>>Well, seems like a pretty sloppy external check (walkaround) to miss
>>something this big, also how did they miss the 781A entry?...good
>>god...
>
>Well, Your right. There were a whole bunch of people that got into a lot of
>trouble , starting with the Crew Chief and working up from there. Someone
>signed off the exceptional release without getting out of the truck and looking
>the plane over. The F/E had his head up his ass and the right seater never
>bothered to check anything out. Other than that is was a great day.
>
>>This one I have trouble with Tom, I can see (barely) getting an engine
>>AND it's prop installed on the wrong side (you said that it's
>>physically possible).
>>
>>But...BUT...if you put a 'left hand tractor prop' on a 'right hand
>>turning engine' then the prop will be turning BACKWARDS!...it won't be
>>REAL EFFICIENT like that Tom, it'll give *really* piss-poor takeoff
>>performance :) ...want to rethink this again?...standing by
>>sir......... :)
>>
>One of the benefits of not having handed engines is that you can install the
>engine in any position on a twin or multi engined plane.
That's true of course...
>If you do have handed
>engines, it is entirely possible to get the wrong engine on the wrong position.
>All as it takes is one person not paying attention.
I'll take your word for it....
> The onlyn difference between handed props is the blades are basically mounted
>backwards, so the leading edge is facing the other direction on one of the prop
>hubs. The hubs remain the same because the engine turnes in the other
>direction, and the props are mounted to the crankshaft which is just a splined
>shaft to fit the splines in the prop hub. Of course there is a little more to
>it than that, like shims, governors, oil ports, pitch control, etc.
Sounds right so far...
> So actually, if you really want to get very technical, props on the front of
>the wing are also pushers just like a B-36.
Not a chance, props on the front of the engine are 'tractors'...in
other words, they 'pull'...(and by the 'front of the engine' I mean
'towards the front' of the a/c).
>Why? because after you get the prop
>installed on the crankshaft, you install a very large retaining nut which is
>what the prop pushes against.
> Cheers,
> Tom
<snort> C'mon Tom, who're you trying to buffalo here?, you might
possibly get away with this in a non aviation group but not
here...gee...why not just admit your error?...
Do you actually not understand that a propeller designed to turn
*left-handed* will, when installed so as to be rotated *right-handed*
will not work properly?... BIGTIME?...golly me...<sigh>