Do Flaps Increase Gliding Distance???
RHammell
John Stephens
RHammell <rham...@aol.com> wrote:
|> Question...Flaps increase lift but do they increase gliding distance?
Absolutely not! At least not in any GA aircraft that i am
familiar with. The added drag more than offsets any added lift --
the result is a marked steepening of the glide path.
There is one special case where the sudden application of flaps
can allow one to "jump" over an obstacle, but the resultant glide
is still shortened, and the manoever is a "last ditch attempt" to
avoid a fence, tree, etc. The resultant stall could also ruin
your day!
Bob Noel
wrote:
> Question...Flaps increase lift but do they increase gliding distance?
not on my Cherokee 140.
--
Bob Noel aka Kobyashi Maru
my views are my own not MITRE's
(why use a disclaimer when people are
too --------- to understand it?)
patterson,george r
RHammell <rham...@aol.com> wrote:
>Question...Flaps increase lift but do they increase gliding distance?
No. They increase drag more than they increase lift, so the gliding
distance is less with flaps down than with 0 degrees flaps.
-----------------------------------------------------------------------
|
George Patterson - | In order to get a loan, you must first prove that
| you don't need it.
|
-----------------------------------------------------------------------
Camille Arsenaul
>
> Question...Flaps increase lift but do they increase gliding distance?
Nope! I wouldn't say so. In fact I would say that they decrease the
gliding distance. When do you use flaps? Well, one situation is when
you are approaching a field too high. You lower the flaps and you get
to the field at a lower, safer altitude, but you don't really glide any
further than if you would have just continued without flaps. When practicing
forced approaches, the only time I use flaps are when I'm sure I've made my
field and I have some altitude to lose. I've missed a few forced approaches
because I lowered the flaps too soon and ended up too far away from my
field.
May all your skies be blue!
Camille
camille....@nrc.ca
Camille Arsenaul
Jeffry Stetson
>
>
>All replies so far have said that flaps reduce gliding range. I do believe this to be the
>case in a piper which must implement flaps in rather large stages. In airplanes with variable
>flap deployment (Cessna, Mooney, Piper twins) I am not sure that a few degree flap deflection
>at the proper speed might not be a bit more efficient.
>
>I have no strong evidence to back this up but I do have one data point. While recently
>getting my multi, I did note that the Twin Comanche had the same sink at no flaps and 15
>degrees flaps during the drag demo. This would at least indicate parity and maybe indicate a
>benefit between 0-15.
>
I have yet to see a POH for any production powered aircraft that recommends
the use of flaps to extend gliding range. Be careful with your terms, though.
Minimum sink speed is not best glide (L/D) speed. Perhaps an example from the
soaring world would help.
Gliders in the 15 meter racing and open classes are generally equipped with
wing flaps. Best L/D is about 55-60 kts, flaps up (0 deg). Lowest stall
will be at about +30 degrees, and about 35 kts. Minimum sink rate will be
a few kts over stall speed with 'a little' flap, maybe +10 deg. The setting
for thermalling (circling in rising air) will be one notch more, maybe 15 deg,
depending on the thermal [a little more sink, but a lower stall speed allows
a tighter circle nearer the 'core' of the rising air]. For landing, some
ships allow +90 degrees of flap! The range from 30-90 degrees does nothing
but add drag and the stall speed may even increase a little. Now at higher
speeds, ~80 kts, the flaps will be reflexed, that is extended upwards a few
degrees. This improves the L/D _at that speed_ by reducing trim drag, but
this L/D is considerably less than that achieved at the lower speed without
flaps.
One has to think of wind as well. In a zero-wind condition, the best speed
to cover the most distance over the ground is, simply enough, the best
L/D speed for that aircraft. In a tailwind condition, the best speed will
be less than this, but always higher than the minimum sink speed. In a
headwind condition, fly faster than best L/D speed to cover the most distance.
Adding half the headwind component to the Best L/D speed is a reasonably
good rule-of-thumb. If you can't remember the numbers, flying a little
too fast is better than flying a little too slow, since the 'hook' on
the drag curve is much steeper on the low-speed side.
>Any comments from the aerodynamically brilliant?
Not! But being aerodynamically desperate (no engine) helps in seeing what's
going on.
--
Jeffry Stetson ... Comm ASEL, Pvt SES & Glider, Instrument Airplane
EAA, SSA, AOPA, IAC, MAPA
Mooney M20E "Superduper 21"
Salto H-101 "Shiva - The Cosmic Dancer"
Keith Barr
RHammell <rham...@aol.com> wrote:
>Question...Flaps increase lift but do they increase gliding distance?
No, because they also increase drag, thereby lowering the lift to drag
ratio, which is equivalent to the glide ratio. If lowering flaps increased
glide range, that would be indicative of a wing that was improperly
designed, because L/D is something that should be maximized in the initial
design. If lowering the flaps increased L/D, you would want to fly around
all the time with the flaps down.
___________________________________ _____
| Keith Barr ba...@netcom.com \ \ \__ _____
| COM-ASMEL-IA-A&IGI \ \ \/_______\___\_____________
| Broomfield, Colorado, USA }-----< /_/ ....................... `-.
| http://chinook.atd.ucar.edu/~barr / `-----------,----,--------------'
|___________________________________/ _/____/0
Wayne Rohde
>In article <3s2qvb$3...@newsbf02.news.aol.com>,
>RHammell <rham...@aol.com> wrote:
>|> Question...Flaps increase lift but do they increase gliding distance?
>Absolutely not! At least not in any GA aircraft that i am
>familiar with. The added drag more than offsets any added lift --
>the result is a marked steepening of the glide path.
>There is one special case where the sudden application of flaps
>can allow one to "jump" over an obstacle, but the resultant glide
>is still shortened, and the manoever is a "last ditch attempt" to
>avoid a fence, tree, etc. The resultant stall could also ruin
>your day!
I couldn't agree more.
Works like this in any aircraft i've ever flown (civil and military).
Regards,
Wayne Rohde...
(wro...@ozemail.com.au)
"All I want is peace, good will on Earth
and infinite power..."
Andrew Boyd
>rham...@aol.com (RHammell) wrote:
heh heh ... generalizations can bite you (I wonder if this one will bite
me? :) The answer is, "it depends". It depends on the wing, and it depends
on the flap.
A split flap is unlikely to help your gliding distance, but a few degrees
of a fowler flap just might.
I have a very rough rule of thumb concerning flap extension in
bugsmashers:
0 -> 15 degrees: increases lift (at the cost of increased drag)
Beyond 15 degrees: increases drag (and doesn't increase lift very much)
Obviously, what the POH says is better than any rule of thumb. So why
don't we do that. For a 1975 C-172:
Stalling Speed (mph cas, 2300 lbs, wings level)
--------------
Flaps Up 57
Flaps 10 52
Flaps 40 49
Note that the first 10 degrees of flap extension bought us 5 mph of
stall speed reduction. But the next 30 degrees only bought us 3 mph,
so if we linearly interpolate (physicists, avert your eyes! :) we
only got 1 mph of Vs reduction for each additional 10 degrees of flap.
Many, many a/c, if they have the power (eg mooney, C-182, etc) recommend
taking off with around 15 degrees of flap.
Going back to your answer, Camille:
>> Question...Flaps increase lift but do they increase gliding distance?
>
>Nope! I wouldn't say so.
Food for thought: the emergency checklist for my maule says in
the event of an engine failure, to fly 85 mph, and extend takeoff
(15 degrees of) flap. Hmmmm.
--
#include <std.disclaimer>
David Cristol
All replies so far have said that flaps reduce gliding range. I do believe this to be the
case in a piper which must implement flaps in rather large stages. In airplanes with variable
flap deployment (Cessna, Mooney, Piper twins) I am not sure that a few degree flap deflection
at the proper speed might not be a bit more efficient.
I have no strong evidence to back this up but I do have one data point. While recently
getting my multi, I did note that the Twin Comanche had the same sink at no flaps and 15
degrees flaps during the drag demo. This would at least indicate parity and maybe indicate a
benefit between 0-15.
Any comments from the aerodynamically brilliant.
--
David Cristol
dacr...@globalvision.net
Robert Comperini
>> Question...Flaps increase lift but do they increase gliding distance?
No! If it did, you would find an "extend flaps" instruction in your
emergency engine out procedures, right?
The additional lift you get by using one or two notches of flap can be
used for such things as reducing the diameter of a 180 degree turn after
you find yourself in a box canyon.
--
----------------------------------------------------------------------
| Robert Comperini, KN6EZ Packet: KN6EZ@KB6ZBI.#soca.ca.usa.na |
| Lancaster, California E-Mail: rob...@qnet.com |
| PP A-SEL, USUA BFI #A016560, CAPT CAP |
Camille Arsenaul
I must admit, I did write that response in haste and you are correct in
that "it does depend on the aircraft you're flying". All of my flying experience
has been on Cessna 150s, 172s, 172RGs and so far ~15 hrs on a Piper Arrow (RG). In
all cases, during a simulated forced approach I never use the flaps until I'm sure
I've made my field. But in regular flight, I hardly ever use flaps to land except
in the Piper where I use flaps all the time when landing.
Anyway, your generalization will not bite you this time ... :> but I have noticed
that you post alot so you'd better beware because one of them might just bite...;}
Andrew Boyd
>I have yet to see a POH for any production powered aircraft that recommends
>the use of flaps to extend gliding range.
please email me (ab...@qnx.com) your fax # (or post it here if you like
to live on the wild side :) and I will fax you the POH, such as it is,
for my 1967 maule M4-210C which specifically states that in the event
of an engine failure to extend 15 degrees of flaps and fly 85 mph.
--
#include <std.disclaimer>
Andrew Boyd
>But in regular flight, I hardly ever use flaps to land except
>in the Piper where I use flaps all the time when landing.
Hm. A "normal" landing for me is usually full flap, in all of
the aircraft that I fly: maule, mooney, cessnas, twins etc.
Unless there's a good reason not to use full flap (eg a *very*
strong crosswind) I like the deceleration that full flap gives
me - reduces the time that you spend floating after the flare.
Gets the nose down, too. Improves the vis in the flare.
Also reduces your landing distance. Might reduce the wear and
tear on the brakes.
I personally like to put down around 10 degrees of flap while
on downwind, even with a real humdinger of a crosswind.
As we discussed, this will give you the majority of stall speed
reduction before your turns onto base and final, which means
you're less likely to become a stall/spin statistic.
>I have noticed that you post a lot
every post of mine is guaranteed to be worth exactly what you
paid me for it :)
>so you'd better beware because one of them might just bite...;}
been there, done that, bought the t-shirt and the mug :)
>May all your skies be blue!
ditto!
--
#include <std.disclaimer>
Todd Pattist
>wing flaps. Best L/D is about 55-60 kts, flaps up (0 deg). Lowest stall
>will be at about +30 degrees, and about 35 kts. Minimum sink rate will be
>a few kts over stall speed with 'a little' flap, maybe +10 deg. The setting
>for thermalling (circling in rising air) will be one notch more, maybe 15 deg,
>depending on the thermal [a little more sink, but a lower stall speed allows
>a tighter circle nearer the 'core' of the rising air]. For landing, some
>ships allow +90 degrees of flap! The range from 30-90 degrees does nothing
>but add drag and the stall speed may even increase a little. Now at higher
>speeds, ~80 kts, the flaps will be reflexed, that is extended upwards a few
>degrees. This improves the L/D _at that speed_ by reducing trim drag, but
>this L/D is considerably less than that achieved at the lower speed without
>flaps.
If you're looking for the exception, the Ventus A with 16.6 meter tips
is one of the few sailplanes where flight tests (Dick Johnson) have
shown the best L/D (50:1) occurs with one notch of flaps (+5.1
degrees). I'm looking at the polar as I type. Most get best L/D with
0 degrees as you say. I just bought a Ventus C 16.6 and am trying to
decide if the results for the A model ought to be used.
Todd Pattist
-----
"Fly more X-country: most accidents occur at airports."
-----
R. Kyle Schmidt
Some aircraft do require the extension of a moderate degree of flaps to
acheive their best glide ratio. The Diamond Katana (new two place
trainer) requires the extension of flaps 1, or take off flaps for best
glide. This is because in cruise, the Katana flies with negative flaps,
ie flaps up beyond the wing. This reduces lift, and hence its associated
drag.
R. Kyle Schmidt
Steven Bacci
glide performance. Best glide was at 75kts clean.
Here's an extract from my RAF training notes:
'Drag. Any factor that increases the drag of an aircraft gliding at a
given speed will alter the L/D ratio and, therefore, adversely affect
the gliding performance. A Bulldog gliding at 75 kts with the flap
selected will have a steeper angle of glide and a higher rate of
descent than a 'clean' aircraft descending at the same speed.'
Hope you found that useful.
Steve Bacci
St...@grnfld.demon.co.uk
R. Kyle Schmidt
>the story of the ATP who slipped an airliner into a closed (X) field
>with picknicker's all about. There are no procedure's (apparently) for
>slipping a 737 or whatever it was. But the pilot saw he was high, he
>had no power and only one landing attempt. He performed the manuver
>that applied to aircraft before the days of flaps which allowed a
>decrease in altitude without an increase in airspeed.
>
>Lawson...
>
The story you refer to is that of the Gimli Glider, an Air Canada 767
that ran out of fuel and glided to land at an airstrip in Gimli,
Manitoba, Canada. The pilot landed the 767 on the closed runway at the
field on which there was an autocross or other car event occurring.
The toll... One broken nosegear, one small nosegear well fire, none dead,
and a big lawsuit between the pilot and Air Canada over wrongful dismissal.
The aircraft still flies with AC, and the pilot was reinstated after
receiving legal support from the CALPA.
Just goes to show, never stop flying the airplane.
R. Kyle Schmidt
ps, there is a book written about this incident called "Freefall"
Roderick Filer
Elbert Poling (bond...@ix.netcom.com) writes:
> In <3s3j9l$7...@access2.digex.net> step...@access2.digex.net (John
> Stephens) writes:
>>
>
> While I live by those rules, and I am still living, I will never forget
> the story of the ATP who slipped an airliner into a closed (X) field
> with picknicker's all about. There are no procedure's (apparently) for
> slipping a 737 or whatever it was. But the pilot saw he was high, he
> had no power and only one landing attempt. He performed the manuver
> that applied to aircraft before the days of flaps which allowed a
> decrease in altitude without an increase in airspeed.
>
be a good thing to do, I'd point out that perhaps the ATP had no choice -
sideslip or die. As you point out, he had no power, and that may have
disabled his ability to use the flaps. So sideslipping was the last
resort. By the way the ATP was concerned that while sideslipping he
might have accidentally touched a wingtip on the ground and cartwheeled
the plane. Perhaps, if he had had the choice of using flaps he might
have done so in order to avoid this hazard.
By the way, the plane was an Air Canada 767 (fleet member number
604), and the airport was the abandoned Gimli manitoba airport. On
the occasion wher the captain landed his 767 there was a rally
from the local Gimli autosport club.
Regards
Rory
Barney Schwenzer
I find if I set the engine rpm to go about 90kts which is real slow
for a Tiger. Then I lower the flaps a little. The nose points
down for better visibility, but I notice the airspeed will slow about
3 kts, while maintaining airspeed. This means parasitic drag increases.
From this obsevation I would say it is better to keep the flaps up.
I have a friend in Texas who disagrees. Cutting drag and maintaining lift
is the most important thing to get the best glide.
Elbert Poling
>familiar with. The added drag more than offsets any added lift
I tend to disagree. The first 10 degrees of flap will provide more lift
while having a negligible effect on airspeed. Anything more than that
will, however, produce more drag than lift.
>the result is a marked steepening of the glide path.
The application of flaps will not necessarily increase the angle of the
glide path. The primary purpose of flaps is to allow a decrease in
altitude without an increase in airspeed. This does not necessarily
translate in to an increased glide path. It simply means you will fly
the same (approx.) 3 degree glide slope an a slower airspeed. There are
two prerequisites to landing.
You gotta slow down and you gotta go down.
>There is one special case where the sudden application of flaps
>can allow one to "jump" over an obstacle,
You are correct if you replace 'the sudden application of flaps' with
'applying 10 degrees of flaps.' I once took of with 3000' of runway
available in a C-150. Hot day and all that with a 140 lb. passenger. I
had taken flight instruction in the same plane with heavier people. Yet
on this day once the little plane got out of ground effect it settled
into a gentle (50 fpm) descent. Whle at full power and Vy, I noted the
descent by the VSI and the seat belt gently tugging at my belly. While
holding faithfully at Vy, my first instinct was to turn back via the
pattern albiet far below TPA. Prior to commenceing any turn I was
fortuate enough to realize I didn't have enough vertical lift to trade
for horizontal lift since I was already in a descent and any rolling in
either direction would have resulted in either a more rapid rate of
descent if not an accelerated stall which unfortunatley would have
resulted in a spin at about 150' AGL. Not a workable thing.
My only option was to continue to hold Vy and stay wings level. At this
point we were still in a descent and I had spotted the scene of the
impending accident. As Murphy would have it, it was a junk yard. My
next thought was to apply 10 degrees of flaps to give myself a bit more
lift. For as many takeoffs there are as many landings and, flying the
typical pattern, one will decrease power to approx. 1700 rpm's and
apply 10 degrees of flaps once adjacent to the landing point on the
runway. I have hardly if ever noticed a significant decrease in
airspeed when applying this initial setting. But, in the case of the
descent on takeoff, I was not willing to compromise even a fraction of
KIAS for anything. At about that point I realized a transition from the
seatbelt tugging at my belly to the seat pushing against my butt.
Someone was on my side. It was either God or my Grandaddy.
Even if the flaps would have given an increase in glide distance, I
still would not have cleared the junk yard and what lay beyond it was
far worse than crashing into parked automobiles.
The chips were down, I kept flying the airplane and it flew. If I had
seen somewhere in all of my training (the same we've all had) that one
of the emergency procedures was to apply 10 degrees of flaps, I
would've done it in a second. But it wasn't and I didn't and I will
never know what would have happened if I would have. All's I know is I
followed my training and I'm here to tell the story.
>the manoever is a "last ditch attempt" to >avoid a fence, tree, etc.
I didn't get close enough to the cars....
>The resultant stall could also ruin your day!
If you look in the pilot's handbook of aeronautical knowledge you will
see a drawing of an aircraft on a forced landing attempt. The point of
the illustration is to demonstrate that when one picks a spot to touch
down on and focuses on that point as a reference for descent, the plane
will glide past that point once in ground effect. If your forced
landing precludes that you must cross a fence prior to touch down, you
should actually target the fence or slightly before it. The reason is
that you will glide over the fence and still have the maximum amount of
field left to roll to a stop. Targeting beyond the fence will result in
a significant decrease in stopping distance if the clearing is bordered
by ANY obstacles.
Another thing to think about is that during training and the instructor
pulls the throttle to idle and says "You just lost your engine," The
Pilot's operating handbook will tell you the best glide speed and give
an example of the projected glide path for the aircraft at maximum
gross weight. Nowhere does it say anything about applying any flaps to
increase gliding distance in a forced landing. In a forced landing
scenerio, flaps should be applied when and ONLY when one know's they
have the "runway."
While I live by those rules, and I am still living, I will never forget
the story of the ATP who slipped an airliner into a closed (X) field
with picknicker's all about. There are no procedure's (apparently) for
slipping a 737 or whatever it was. But the pilot saw he was high, he
had no power and only one landing attempt. He performed the manuver
that applied to aircraft before the days of flaps which allowed a
decrease in altitude without an increase in airspeed.
So what have I told you here? Nothing if you weigh the differences
between the way I handled my thing and the ATP handled his. I followed
the training I had and lived. He applied his aeronautical knowledge and
did the same.
What's the moral of the story?? Get out there and fly. If you want to
test a theory, do it at altitude and know what to expect when the real
thing happens because 'peace of mind IS a tangible thing.'
Lawson...
Kelly McLellan
In article <3stdhj$6...@ixnews4.ix.netcom.com>, bond...@ix.netcom.com (Elbert Poling ) writes:
|> In <3s3j9l$7...@access2.digex.net> step...@access2.digex.net (John
|> Stephens) writes:
|> >
|> >Absolutely not! At least not in any GA aircraft that i am
|> >familiar with. The added drag more than offsets any added lift
|>
|> I tend to disagree. The first 10 degrees of flap will provide more lift
|> while having a negligible effect on airspeed. Anything more than that
|> will, however, produce more drag than lift.
|>
Generaly true but I would not want to apply flap unless I had a place to land
(i.e. when I want to get out of the air and not stay in it). The wing of a plan
is designed to give the lift that you need after all.
What were you thinking at the time???!!! If you want to stay in the air, your
nose is up, you are going down then GET YOUR NOSE DOWN!!!!!! It sounds like you
were in a strong down draft and there was not much you could have done about it
except get through it as fast as possible. But what if you were stalling? In
either case get your nose down. At least - or at worst - that way you would
be in more control of your landing.
|> >the manoever is a "last ditch attempt" to >avoid a fence, tree, etc.
|>
|> I didn't get close enough to the cars....
|>
|> >The resultant stall could also ruin your day!
|>
Not could. Would.
|> If you look in the pilot's handbook of aeronautical knowledge you will
|> see a drawing of an aircraft on a forced landing attempt. The point of
|> the illustration is to demonstrate that when one picks a spot to touch
|> down on and focuses on that point as a reference for descent, the plane
|> will glide past that point once in ground effect. If your forced
|> landing precludes that you must cross a fence prior to touch down, you
|> should actually target the fence or slightly before it. The reason is
|> that you will glide over the fence and still have the maximum amount of
|> field left to roll to a stop. Targeting beyond the fence will result in
|> a significant decrease in stopping distance if the clearing is bordered
|> by ANY obstacles.
|>
|> Lawson...
Eh? Aim for a point before the fence? Aim for the fence? In an emergency
situation? Learn to fly is the best answer. Learn to land the plan where YOU
want it and not where it wants to. In the UK if you aimed for a fence (which
are stone dikes) you would probably hit it with your wheels and nose into the
ground. WAHM!! Bad day.
Every pilot should be able to put a plane on the ground where he wants to put it.
This requires skill and not stupid tricks. Anyone who has ever been in a sticky
situation or if you think back to your first few landings you should know that
you hit what you aim for.
Kelly McLellan
Julian Scarfe
> Yet
> on this day once the little plane got out of ground effect it settled
> into a gentle (50 fpm) descent. Whle at full power and Vy, I noted the
> descent by the VSI and the seat belt gently tugging at my belly. While
> holding faithfully at Vy, my first instinct was to turn back via the
> pattern albiet far below TPA...
In article <1995Jun30....@nmra.bioch.ox.ac.uk>,
mcle...@bioch.ox.ac.uk (Kelly McLellan) wrote:
> What were you thinking at the time???!!! If you want to stay in the air, your
> nose is up, you are going down then GET YOUR NOSE DOWN!!!!!!
Why? He's already at maximum rate of climb airspeed -- all that sticking
the nose down and increasing speed can do is make things worse: the
immediate response is a loss of altitude to increase the KE, the longer
term effect is to increase drag and so increase the steady state rate of
descent, and to cap it all if the aircraft is going to hit something,
it'll hit it harder.
Julian Scarfe
ja...@cus.cam.ac.uk
Kelly McLellan
In article <jas12-30069...@131.111.200.2>, ja...@cus.cam.ac.uk (Julian Scarfe) writes:
|> In article <3stdhj$6...@ixnews4.ix.netcom.com>, bond...@ix.netcom.com
|> (Elbert Poling ) wrote:
|>
|> > on this day once the little plane got out of ground effect it settled
|> > into a gentle (50 fpm) descent. Whle at full power and Vy, I noted the
|> > descent by the VSI and the seat belt gently tugging at my belly. While
|> > holding faithfully at Vy, my first instinct was to turn back via the
|>
|> In article <1995Jun30....@bioch.ox.ac.uk>,
|> mcle...@bioch.ox.ac.uk (Kelly McLellan) wrote:
|>
|> > What were you thinking at the time???!!! If you want to stay in the air, your
|> > nose is up, you are going down then GET YOUR NOSE DOWN!!!!!!
|>
|> Why? He's already at maximum rate of climb airspeed -- all that sticking
|> the nose down and increasing speed can do is make things worse: the
|> immediate response is a loss of altitude to increase the KE, the longer
|> term effect is to increase drag and so increase the steady state rate of
|> descent, and to cap it all if the aircraft is going to hit something,
|> it'll hit it harder.
|>
|> Julian Scarfe
|> ja...@cus.cam.ac.uk
I said why in my posting - he did not seem to know why he was going down. By
only leveling out it seems to me that he was letting external forces control
the plane and not controling it himself. If you are stalling or something is
wrong with the aircraft then you need to lose hight to fix the situation anyway.
At this point in time how fast you hit the ground is a mute point - it is how
you hit the ground. Are you going to hit it going down on your undercarrage
with your nose high or are you going to hit it whilst in positive control of
the airplane?
The problem is "I am losing altidude - how am I to rectify the situation?"
Kelly
Kelly McLellan
On Sat, 1 Jul 1995, Julian Scarfe wrote:
> In article <1995Jul1.1...@nmra.bioch.ox.ac.uk>,
> mcle...@bioch.ox.ac.uk (Kelly McLellan) wrote:
>
> > I said why in my posting - he did not seem to know why he was going down. $
> > only leveling out it seems to me that he was letting external forces control
> > the plane and not controling it himself. If you are stalling or something $
> > wrong with the aircraft then you need to lose hight to fix the situation
> anyway.
>
> If you are stalling, yes. If something else is wrong with the aircraft,
> not necessarily.
>
> Given that the cause was unknown, why did you deduce that sticking the
> nose *down* would improve matters? If he was just in a downdraft, the
> best he could hope for would be to minimize his rate of descent until he
> escaped the downdraft, which he would do by maintaining Vy (maximum rate
> of climb).
>
> You seem to be convinced that he was stalling -- I don't think that was
> likely at Vy. That's why I jumped on your response!
>
No. The first thing I said was that "It sounds like you
were in a strong down draft and there was not much you could have done
about it except get through it as fast as possible."
My thinking was that he did not seem to know what was happening to his
aircraft. The thought of a down draft never came up. For any beginer
pilots out there it seems to me that the best advice for that type of
aircraft. The thought of a down draft never came up. For any beginer
pilots out there it seems to me that the best advice for that type of
situation is exactly what you wrote below. He should not be bragging
about keeping his nose up. Perhaps I am wrong but id he was in a down
draft then the best he could do is get out of it as fast as possible? It
does depend on how much hight he has left (he never said) and how fast
he is going down.
However, I was thinking more along the lines that he did not seem to know
what was happening. Could he have done something wrong? Is the plane in
a position that he did not expect it to be in - hence inducing a stall -
even though he knows that he should be at Vy he does not know that for sure.
Or is there something wrong with the plane?
I know that I could be wrong. I have been in similar situations and
knowing that I was flying through a downdraft I kept my climbing
attitude. If I paniced and nosed down perhaps I could have made one of
those situations worse. :|
> > The problem is "I am losing altidude - how am I to rectify the situation?"
>
> True enough, but "nose down" isn't some sort of panacea. It only works if
> you're at a point on the "drag curve" where increasing airspeed increases
> excess power. Certainly the non-intuitive response (nose down increases
> ROC) catches out a lot of people who get themselves into low speed
> go-around situations and can't bring themselves to stick the nose down,
> but I don't think that was the problem here.
>
> Julian Scarfe
> ja...@cus.cam.ac.uk
>
Kelly McLellan
Angelo Campanella
>Generaly true but I would not want to apply flap unless I had a place to land
>(i.e. when I want to get out of the air and not stay in it). The wing of a
>plan
>is designed to give the lift that you need after all.
The best speed for distance is VY, for that speed requires the least power
to (that's why the plane climbs fastest!). Actually, the best distance speed
is a tad faster than that, getting more distance at a very slightly
increased sink rate.. but you really want time to look around, so VY is not
so bad a choice after all.. Flaps will reduce that VY speed a little...
More apropors to having a slower landing speed.
Ang
/\/\/\/\/\/\/\ Sound Technology /\/\/\/\/\/\/\/\/
patterson,george r
Elbert Poling <bond...@ix.netcom.com> wrote:
>In <3s3j9l$7...@access2.digex.net> step...@access2.digex.net (John
>Stephens) writes:
>>There is one special case where the sudden application of flaps
>>can allow one to "jump" over an obstacle,
>
>You are correct if you replace 'the sudden application of flaps' with
>'applying 10 degrees of flaps.'
John is correct as he states it. Read _Fate is the Hunter_ for a very
dramatic example of this. Or you can check out the short field takeoff
technique specified for a Maule. One notch of flaps (10 degrees) is used
for normal takeoff. At about 40 mph, slam down full flaps, and the aircraft
essentially levitates about 50 feet. You then have to retract the flaps
again fairly rapidly, or she'll come right back down.
Gann used application of full flaps (as John states) to rapidly gain
altitude for a short period of time, "jumping" over the Taj Mahal. This
sort of effect is most easily demonstrated in an aircraft which has a
manual flap extension system.
-----------------------------------------------------------------------
|
| It is better to have loved and lost.
George Patterson - |
| Much better.
|
-----------------------------------------------------------------------
Jeffrey M. Matthews
patterson,george r <pat...@cc.bellcore.com> wrote:
>In article <3stdhj$6...@ixnews4.ix.netcom.com>,
>Elbert Poling <bond...@ix.netcom.com> wrote:
>>Stephens) writes:
>
>>>There is one special case where the sudden application of flaps
>>>can allow one to "jump" over an obstacle,
>>
>>You are correct if you replace 'the sudden application of flaps' with
>>'applying 10 degrees of flaps.'
>
>dramatic example of this. Or you can check out the short field takeoff
>technique specified for a Maule. One notch of flaps (10 degrees) is used
>for normal takeoff. At about 40 mph, slam down full flaps, and the aircraft
>essentially levitates about 50 feet. You then have to retract the flaps
>again fairly rapidly, or she'll come right back down.
>
In many planes one does have to get rid of some flap after a jump takeoff.
But the owner's manual (not an approved flight manual, they came later)
for my Super Cub said basically "...when takeoff speed (35 mph) is attained,
apply full [50 degrees] flap. The aircraft will be capable of a steep
climb." I did it numerous times and found no tendency to quit climbing
right up to the max allowable gross. One had to push the nose down a bit
to accelerate to a speed where the ASI worked, and I found 50 to be a lot
more comfortable, as that was an excellent glide speed with full flap and
no power--lots of energy to flare with.
Of course the flaps on the Super Cub were not as big as those on most
Cessnas, nor quite as effective. And nobody's built a wing that's as
forgiving as the Cub's. But the flaps were pretty effective--better by
far than those on Citabrias and Scouts.
Jeff Matthews
Les Niles
>On Sat, 1 Jul 1995, Julian Scarfe wrote:
>> Given that the cause was unknown, why did you deduce that sticking the
>> nose *down* would improve matters? If he was just in a downdraft, the
>> best he could hope for would be to minimize his rate of descent until he
>> escaped the downdraft, which he would do by maintaining Vy (maximum rate
>> of climb).
>>
>were in a strong down draft and there was not much you could have done
>about it except get through it as fast as possible."
>>
>> True enough, but "nose down" isn't some sort of panacea. It only works if
>> you're at a point on the "drag curve" where increasing airspeed increases
>> excess power. Certainly the non-intuitive response (nose down increases
>> ROC) catches out a lot of people who get themselves into low speed
>> go-around situations and can't bring themselves to stick the nose down,
>> but I don't think that was the problem here.
OK, I'll play virtual-Steve-Philipson here.
Kelly is right, lowering the nose isn't just for when you're on the back
side of the power curve. In a strong downdraft the optimal response is
often to lower the nose, not because it increases ROC -- ROC will
decrease -- but in order to get out of the sinking air as quickly as
possible. The rate of descent will be higher, but for a shorter time
than if Vy is maintained, so the total altitude loss in escaping the
sink will be less. This assumes the downdraft has a limited horizontal
extent, which is the case with mountain wave and convective activity.
Glider pilots use this technique all the time, and its converse: Raise
the nose in rising air, to slow down below Vy and spend more time in the
lift.
Of course in any particular situation the absolute best response will
depend on rate of climb, strength of the downdraft, and whether there's
a headwind or tailwind. Former (or sporadic) rec.aviator Steve
Philipson did some analysis and developed a couple of simple
rules-of-thumb:
### In a headwind, if you're at Vy and descending at TWICE the rate that
### you should be going up, it's time to put the nose down and get out
### of that area as quickly as possible.
### In a tailwind or no wind, if you're at Vy and descending at THREE
### times the rate that you should be going up, it's time to put the nose
### down and get out of that area as quickly as possible.
One of the AOPA Pilot columnists -- I think it was Barry Schiff --
discussed this and quoted Steve, sometime in the last year or two.
-les ni...@parc.xerox.com
Mooney N9752M
Julian Scarfe
ni...@parc.xerox.com (Les Niles) wrote:
Les> OK, I'll play virtual-Steve-Philipson here.
Does that mean I can play virtual-Craig-Wall? ;-)
Les> Kelly is right, lowering the nose isn't just for when you're on the back
Les> side of the power curve. In a strong downdraft the optimal response is
Les> often to lower the nose, not because it increases ROC -- ROC will
Les> decrease -- but in order to get out of the sinking air as quickly as
Les> possible. The rate of descent will be higher, but for a shorter time
Les> than if Vy is maintained, so the total altitude loss in escaping the
Les> sink will be less. This assumes the downdraft has a limited horizontal
Les> extent, which is the case with mountain wave and convective activity.
It's a good point Les, but you make two important assumptions. One is
that you have the extra altitude to play with while you stick the nose down.
If you're a glider at 1000 ft just wanting to make some net altitude
for the bank account, the investment may well be worth it. If you're a
light single climbing out and you hit a downdraft at 100 ft, that
venture capital may not be available in the quantity you require. ;-) Rigidly
maintaining Vy might make the difference between climbing and not. So the
calculus gets a little complicated...
The second assumption is things are going to get better ahead. You're right,
it's usually true for mountain waves, but I'm not so sure about convective
activity. It might be worth a very gentle turn away from that CB!
You have to take each situation as it arises. I'm not sure that the
original poster gave us enough info to tell what the correct action should
have been.
Julian Scarfe
ja...@cus.cam.ac.uk
NewPiolt
and distance in air. Flaps are to allow a steeper angle of decent at same
TAS.
Jason Frehner
If you take at the lift/drag ratio curve there is one airspeed (angle of attack)
for the flattest glide (therefore the range is maximum).The aircraft must be
operated at the(L/D)max. The highest value of (L/D) will occur with the a/c
in the clean configuration. Thats why when your taught forced landings to lower
flap when you are sure you are going to make it or you are going to overshoot.
I hope this helps you.
Barney Schwenzer
thought.
I tried the experiment again with my Grumman Tiger by putting
down a very small amount of flaps. I should say that I have
flaps raised 3 degrees for more speed, but now we are talking
slow speed flight. When I put the flaps down the nose pitches
up alittle so I trim it down a little. I noticed the difference
in speed to maintain flight was minimal. Over looking thermals
because like gliders you push the nose down to get out of down
drafts as quick as possible.
I thought about this and thought about canards have two lifting
surfaces when they want to go up, where a conventional airplane
has one surface (elevator) pushing down to increase angle of
attack. So if a little flap is put down now and you trim the
elevator to lift a little more plus the angle of attack is reduced.
Increased angle of attack increase lift and parasitic drag. The
elevator is increasing angle of attack down which means we are
putting more force down and adding parasitic drag. At some point
the additional drag from the flap increasing exceeds the lessening
of drag mentioned above.
Since I noticed on the second try no decrease in speed with a very
small amount of flaps and better visibility, I would in the tiger
use a SMALL amount of flap.
Now for the bad news for everyone out there. Put more weight in
the plane actually means you should fly slightly faster then a lightly
loaded airplane. Oh yes what do those antennas do to change the
glide speed. Also the manual listed speed is a compromise at gross
weight. If you have speed mods on it would be alittle better
to glide a little faster.
This is my guestimation for a grumman tiger. I heard mooneys pitch
down when you put the flaps down. So they would be different.
When you are in best glide situation remember to keep flying the
airplane. I have a friend that stopped flying the airplane and
was not able to make the airport when he flew crosswind over
at 1200 agl. He started worrying and fooling with the systems
and stopped flying the airplane. Bad move on his part.
Also best glide is better with a tail wind to cover the distance,
but not to stop quickly on trying to land.
Barney
These are my opinions for today and they could change again tommorrow.
Ron Natalie
: The '67 Chrokee I fly says BEST GLIDE @ 85mph, which means longest time
: and distance in air.
No, it just means longest distance.
: Flaps are to allow a steeper angle of decent at same
: TAS.
Depending on how their used.
Les Niles
>In article <NILES.95J...@ripple.parc.xerox.com>,
>ni...@parc.xerox.com (Les Niles) wrote:
>Les> Kelly is right, lowering the nose isn't just for when you're on the back
>Les> side of the power curve. In a strong downdraft the optimal response is
>Les> often to lower the nose, not because it increases ROC -- ROC will
>Les> decrease -- but in order to get out of the sinking air as quickly as
>It's a good point Les, but you make two important assumptions. One is
>that you have the extra altitude to play with while you stick the nose down.
>If you're a glider at 1000 ft just wanting to make some net altitude
>for the bank account, the investment may well be worth it. If you're a
>light single climbing out and you hit a downdraft at 100 ft, that
>venture capital may not be available in the quantity you require. ;-) Rigidly
>maintaining Vy might make the difference between climbing and not. So the
>calculus gets a little complicated...
I didn't suggest speeding up unless one is *descending* at Vy. If
"rigidly maintaining Vy" gets a positive rate of climb, then Steve
Philipson's rule-of-thumb says to maintain Vy. Only when flying at Vy
results in a considerable rate of descent does he (and I, by quotation)
suggest speeding up. Sure, it's possible in this case that you won't
have enough altitude, but if that's true, you wouldn't have had enough
altitude to avoid the ground even flying at Vy.
It's not really complicated: the goal when terrain clearance becomes an
issue is to maximize *angle* of climb, not *rate* of climb. Or to
minimize angle of descent. If you're in some column of air descending
faster than your airplane can climb, you're going to keep descending
until you get out of that air. Assuming the area of descending air is
fairly constant over the time you're flying through it, the best you can
do is minimize your angle of descent until you get out of that area.
The important observation is that, when you're descending, angle of
descent is minimized at some speed *faster* than Vy, because speeding up
a little increases the horizontal distance traveled proportionally more
than it increases the vertical descent. (Mathematically, because *rate*
of descent is minimized at Vy, its increase is second-order as you speed
up above Vy, while the horizontal speed is of course first order, so
there's a first-order decrease in the ratio [i.e., angle of descent] for
small increases in speed above Vy.) Figuring out the exact optimal
speed would require knowing how fast the air is going down, the L/D vs.
speed curve for the airplane, and how the engine/propellor power output
varies with airspeed. But in practice, getting the exact optimal
airspeed isn't important. What is important is not struggling along at
Vy when that is a hopeless strategy and the minimum-angle-of-descent
speed is considerably higher. That's why Steve suggested a very rough
rule-of-thumb.
Note that the horizontal dimensions of the area of sinking air do not
matter. Minimum angle of descent is minimum angle, regardless of how
far you have to go. The exception is if the area is very small, where
the transient effects of changing airspeed become important.
>The second assumption is things are going to get better ahead. You're right,
>it's usually true for mountain waves, but I'm not so sure about convective
>activity. It might be worth a very gentle turn away from that CB!
Turning away to escape the sink is always a good strategy, if you know
which way to turn!
I wasn't thinking of full-blown thunderstorms so much as just thermal
activity of the sort that's often marked by cumulus clouds. What goes
up must come down. (I had an opportunity to use the above strategy not
too long ago, circling in a somewhat confined area in the mountains to
gain enough altitude to clear the pass I wanted to go over. Turns out
there was a thermal right where I needed to circle, so at least with my
untrained eye half of the circle was in the rising air and half in the
descending air. ROC varied from +1000 fpm to -500 fpm at Vy. By
speeding up in the descent and slowing down in the climb, I was able to
significantly increase the net altitude gain per circle.)
>You have to take each situation as it arises. I'm not sure that the
>original poster gave us enough info to tell what the correct action should
>have been.
I agree. I just wanted to point out that in general speeding up above
Vy is the right thing to do in strong sink.
-les ni...@parc.xerox.com
Mooney N9752M
Pete Bowen
>In article <NILES.95J...@ripple.parc.xerox.com>,
>ni...@parc.xerox.com (Les Niles) wrote:
>Les> OK, I'll play virtual-Steve-Philipson here.
>Does that mean I can play virtual-Craig-Wall? ;-)
>Les> Kelly is right, lowering the nose isn't just for when you're on the back
>Les> side of the power curve. In a strong downdraft the optimal response is
>Les> often to lower the nose, not because it increases ROC -- ROC will
>Les> decrease -- but in order to get out of the sinking air as quickly as
>Les> possible. The rate of descent will be higher, but for a shorter time
>Les> than if Vy is maintained, so the total altitude loss in escaping the
>Les> sink will be less. This assumes the downdraft has a limited horizontal
>Les> extent, which is the case with mountain wave and convective activity.
>It's a good point Les, but you make two important assumptions. One is
>that you have the extra altitude to play with while you stick the nose down.
>If you're a glider at 1000 ft just wanting to make some net altitude
>for the bank account, the investment may well be worth it. If you're a
>light single climbing out and you hit a downdraft at 100 ft, that
>venture capital may not be available in the quantity you require. ;-) Rigidly
>maintaining Vy might make the difference between climbing and not. So the
>calculus gets a little complicated...
>The second assumption is things are going to get better ahead. You're right,
>it's usually true for mountain waves, but I'm not so sure about convective
>activity. It might be worth a very gentle turn away from that CB!
>You have to take each situation as it arises. I'm not sure that the
>original poster gave us enough info to tell what the correct action should
>have been.
This might work well in some situations, but is exactly the WRONG
maneuver in a common downdraft situation---wind shear and microburst
situations. One danger in commercial aircraft is that flight
directors, set for a certain speed, may direct the pilot to lower the
nose to maintain airspeed, thereby causing him to accelerate towards
the ground. The big question in a microburst or windshear situation is
to get away from the ground--usual procedures are to raise nose to
optimal climbout attitude and go to full power. Airspeed, assuming its
above stall speed, is a secondary consideration.... And because
microbursts are short distances across, and the downdrafts so severe,
lowering the nose to fly out the other side faster won't help you...
patterson,george r
NewPiolt <newp...@aol.com> wrote:
>The '67 Chrokee I fly says BEST GLIDE @ 85mph, which means longest time
>and distance in air.
Best glide means longest distance traveled before touchdown. Longest
time in the air is achieved at a somewhat slower speed (usually a little
faster than best angle of climb speed). If you're close to a good field
and want a little more time for radio communication or restart attempts,
you would not want to use the "best glide" speed.
-----------------------------------------------------------------------
| "Under Consideration": We never heard of it.
George Patterson - | "Under Active Consideration": We're searching the
| files for it.
| Kelvin Throop - The Management Dictionary
-----------------------------------------------------------------------
Julian Scarfe
wrote:
> [Lowering the nose] might work well in some situations, but is exactly the
> WRONG maneuver in a common downdraft situation---wind shear and
> microburst situations. One danger in commercial aircraft is that flight
> directors, set for a certain speed, may direct the pilot to lower the
> nose to maintain airspeed, thereby causing him to accelerate towards
> the ground. The big question in a microburst or windshear situation is
> to get away from the ground--usual procedures are to raise nose to
> optimal climbout attitude and go to full power. Airspeed, assuming its
> above stall speed, is a secondary consideration...
So what's the "optimal climbout attitude"? First impression is that it
should be the attitude that gives you Vy for your airspeed, but perhaps
there's more to it than that (because Vy assumes a steady state, with no
accelerations).
Julian Scarfe
ja...@cus.cam.ac.uk
Gavin Nicholson
<Banter between Julian and Kelly deleted>
I'll add my $0.02 worth here Kelly to support what Julian said. In
your first post you quite clearly (at least to me) stated that he
should get the nose down, I disagreed with this entirely. The guy who
had the problem said he was at his climb speed I assume he had no
buffet so it is unlikely he was stalling. He most probably was in a
downdraft of some sort or alternatively he could have been overweight
for the takeoff. In either case I would suggest either (a) do nothing
and brace for impact given you are doing the correct actions as it was
or (b) pull the nose further up and look to fly on the pre stall
buffet. It is at this point you will have maximum lift, indeed a
technique for getting out of microburst windshear is full power on all
engines and pull to the stick shaker. You want to minimise the impact
in any case and pushing the nose down will not do this for you.
Safe Flying,
--------------
Gav.
(One of the last of an endangered species...
....the white heterosexual male......)
WILLIAM BERLE
I was at one time a national speed record holder in gliders. We
had positive / negative deflection flaps on most of our planes
and had to become fairly knowledgeable on how to use them. The
best glide angle for a wing and thus an airplane is with the
flaps retracted or neutural. The best glide ratio over the ground
will occur at some speed greater than the stall, different for
each airplane. The best glide speed is near the best climb speed on
most single engine airplanes.Putting the flaps down to any degree will
lower the glide ratio, but lower the stall speed as well. For best
distance achieved from cruise altitude, in most GA aircraft, one would
leave the flaps in the cruise position (up) until the landing is
imminent.lowering the flaps fully before landing off-airport will
provide the slowest speed. But lowering the flaps during the glide
beforehand will only slow the plane and reduce the distance it can
glide.
Bill Berle
In <3ug61o$4...@kettle.magna.com.au> g...@magna.com.au (Gavin Nicholson)
writes: