The 600 Mph Spitfire :)
Rob Arndt
On April 27, 1944 Sqn. Ldr. Martindale flew a modified Spitfire Mk.XI
(Nr EN 409) in a 45o dive to achieve 606 mph. He lost the plane's
modified prop and had to glide her back to base for 20 miles!
Rob
Keith Willshaw
"Rob Arndt" <teut...@aol.com> wrote in message
news:0c0b1be8-497e-4255...@w39g2000prb.googlegroups.com...
IRC the modifications consisted of fitting a mach meter and fully
feathering Rotol propellor. The test was part of a series intended
to investigate aircraft handling in the transonic region.
Keith
Dingo
"Rob Arndt" <teut...@aol.com> wrote in message
news:0c0b1be8-497e-4255...@w39g2000prb.googlegroups.com...
This Spitfire was the subject of posts here back in February this year. My
post did not gain any responses at the time, so am including it below in the
hope someone can throw a bit of light on the a/c's later life.
~~
Dingo
~~~~~~~
Originally posted tyo r.a.m 26/2/08
Recently read a bit about Spitfire PR Mk XI (EN 409) used for diving trials
which clocked up 606 mph before losing its prop and reduction gear. It
landed safely after a 20 mile glide.
About a year later, 7/4/45, from what I have read, it force landed at
Spanish Point, Miltown Malbay in County Clare on the west coast of the Irish
Republic. It was being flown by Canadian pilot F/O Edward Andrew Miller, who
was, quote, "on recce mission over German flying bomb sites".
What puzzles me is:
(1) if he was on a recce over V.1 sites why did he force land 500 or so
miles away in Eire ?
(2) what was the purpose of the mission given that V.1 sites had fallen
into Allied hands 9 months earlier ?
(3) Given that Eire was neutral, what happend to both a/c and pilot ?
Just curious,
~~
Dingo
Dudley Henriques
fully feathering prop for a high mach number dive test.
--
Dudley Henriques
Keith Willshaw
"Dudley Henriques" <dhenr...@rcn.com> wrote in message
news:8q6dnTsSqKPkATDV...@rcn.net...
As I understand it the idea was to prevent the prop overspeeding,
it didnt work out too well :)
Keith
Dudley Henriques
Looks like it in this Spit anyway :-) I had a 51 in a high mach dive
once (an O2 failure at high altitude really that resulted in the dive)
Woke up at about .70 with the stick walking all over the cockpit and the
prop screaming.
What happens is that the prop tries to stay constant at it's present
setting until it hits the governor stops, then it goes aerodynamic with
the resultant rotational velocity in fine pitch. It's here the real
trouble starts as the tips go supersonic. I was VERY lucky that
afternoon :-))
Herb Fisher did the dive tests in the Jug and I've always regretted
forgetting to ask him where he had his propeller set at the start of his
dives. I would imagine he had it all the way forward in fine pitch to
stabilize the governor. This should have resulted in the prop reacting
completely to aerodynamic factors alone giving him a true prop critical
mach number based completely on the rotational velocity vectors.
I'm just guessing that this was the way he set up his dives.
--
Dudley Henriques
John Carrier
> Looks like it in this Spit anyway :-) I had a 51 in a high mach dive
> once (an O2 failure at high altitude really that resulted in the dive)
> Woke up at about .70 with the stick walking all over the cockpit and the
> prop screaming.
> What happens is that the prop tries to stay constant at it's present
> setting until it hits the governor stops, then it goes aerodynamic with
> the resultant rotational velocity in fine pitch. It's here the real
> trouble starts as the tips go supersonic. I was VERY lucky that afternoon
> :-))
> Herb Fisher did the dive tests in the Jug and I've always regretted
> forgetting to ask him where he had his propeller set at the start of his
> dives. I would imagine he had it all the way forward in fine pitch to
> stabilize the governor. This should have resulted in the prop reacting
> completely to aerodynamic factors alone giving him a true prop critical
> mach number based completely on the rotational velocity vectors.
> I'm just guessing that this was the way he set up his dives.
I'm still incline to believe the Spit's alleged speed was the result of poor
compressibility callibration in the airspeed system. Makes a good story,
but I doubt any WW2 aircraft could get much past .80. The Thunderbolt
allegedly did 700mph until the engineers took a look at the data, applied a
compressibility correction (we have such tables in NATOPS even now) and came
up with about 550mph. Given the Thunderbolt's fame for outdiving EVERYTHING
in the ETO except the jets, a .9 Spit Mark 9 is just a bit beyond belief,
despite the legend reporting the event.
OBTW, .7+ in a Mustang is probably way beyond the thrill of an A-6 at .99
(and I doubt all the thrust in Christendom could not push BUF the lesser
supersonic).
R / John
Dudley Henriques
that .80 would just about tear it for a prop fighter, especially a much
lighter Spit. On this particular dive I believe Herb's .79 computed out
to 560KTAS.
--
Dudley Henriques
Keith Willshaw
"John Carrier" <jx...@comcast.net> wrote in message
news:hL6dnYRl4tD9eTDV...@comcast.com...
>
>> Looks like it in this Spit anyway :-) I had a 51 in a high mach dive
>> once (an O2 failure at high altitude really that resulted in the dive)
>> Woke up at about .70 with the stick walking all over the cockpit and the
>> prop screaming.
>> What happens is that the prop tries to stay constant at it's present
>> setting until it hits the governor stops, then it goes aerodynamic with
>> the resultant rotational velocity in fine pitch. It's here the real
>> trouble starts as the tips go supersonic. I was VERY lucky that afternoon
>> :-))
>> Herb Fisher did the dive tests in the Jug and I've always regretted
>> forgetting to ask him where he had his propeller set at the start of his
>> dives. I would imagine he had it all the way forward in fine pitch to
>> stabilize the governor. This should have resulted in the prop reacting
>> completely to aerodynamic factors alone giving him a true prop critical
>> mach number based completely on the rotational velocity vectors.
>> I'm just guessing that this was the way he set up his dives.
>
> I'm still incline to believe the Spit's alleged speed was the result of
> poor compressibility callibration in the airspeed system. Makes a good
> story, but I doubt any WW2 aircraft could get much past .80.
As it happens in the case of the Spitfire it was part of a sequence of
tests specifically aimed at investigating compressibility and had
an accurately calibrated Machmeter as a result.
Eric Brown covers the subject in several of his articles
Keith
Dudley Henriques
have one for Fisher's if you would like to have one.
--
Dudley Henriques
Peter Stickney
Hey, Dudley, good to see you're still about!
Teathering the prop for a high speed dive (Or pulling it back to
Full Decrease RPM) served 2 purposes. The first is to keep the
prop from overspeeding - doesn't always work, though.) The
second is to reduce drag by keeping the prop from windmilling, and
presenting the least frontal area.
It's worth noting that for the really high speed dive tests of the
P-51, they removed the prop entirely, and towed the resulting glider
to altitude for the dives. (They stuck a battery-powered hydraulic pump
in to run the gear and flaps.)
--
Pete Stickney
Any plan where you lose you hat is a bad plan
John Carrier
"Keith Willshaw" <keith...@demon.co.uk> wrote in message
news:g8kqeo$9m3$1$8300...@news.demon.co.uk...
I know. I just respectfully suggest that the level of ignorance about
transonic effects and compressibility was such at the time that errors were
likely made. How would they KNOW their machmeter was accurate? There were
no supersonic wind tunnels. There were no supersonic aircraft. To put it
into perspective, they don't acknowledge speed records based on aircraft
instrumentation, they base the record on the time it takes the aircraft to
cover a specified course. Everything else is anecdotal.
Interestingly enough, no prop aircraft has ever attempted the absolute speed
record at altitude.
An OBTW, the high-speed Spit never entered the arena, couldn't begin to
match the Me-209's 469mph (a one-off, almost an engine with the pilot
attached to the accessory section). Currently the record is 528.3 mph ...
them props have their limitations, but without them, no thrust and no speed.
R / John
Dudley Henriques
I don't think I'd ever start a high speed dive with the prop in full
decrease. Granted it's closest to a feather with the narrowest blade
angles for the blade set but the thrust issue to get the dive speed up
vs the allowed time line/altitude issue before requiring recovery within
the radial g envelope seems to me to be an even bigger issue than any
alleged advantage on the prop drag curves as opposed to having the
blades in high pitch.
I've never tried it of course but I don't believe I could complete a
takeoff in a 51 with the prop in full decrease before the coolant maxed
and popped off :-)
--
Dudley Henriques
Dan
That's easy; for a given altitude or airspeed there is a known air
pressure measured in inches or millimeters of mercury. Take into account
temperature and you can predict true air speed and mach.
Dan, U.S. Air Force, retired
guy
>
> - Show quoted text -
Given that Eric the RAE was acknowledged to be the world leader in
transonic research at the time, and tested Spits, Tempests, P51s,
P47s,P38s why should only the Spis result be wrong?
Also, although the P47 had phenomenal acceleration going downhill its
limiting Mach number was less than a P51
Guy
Dudley Henriques
Fisher reached .83 tops as far as I can determine. Remember, it wasn't
the airplane's limiting mach number alone but the drag rise on the
propeller as well limiting the dive speeds. Also, there is an altitude
vs time window for a diving airplane trying to max the dive speed.
--
Dudley Henriques
John Carrier
"Dan" <B24...@aol.com> wrote in message
news:MMnrk.1388$_s1....@newsfe07.iad...
BUT, there are compressibility effects in the pitot static system. While
mach is computable from temperature for a given true air speed, you can't
derive the aircraft's TAS with a faulty pitot-static system. Most modern
A/C have an ADC which corrects IAS. Some evidently don't ... the T-45C
being an example. I doubt any did in WW2.
R / John
John Carrier
>.Given that Eric the RAE was acknowledged to be the world leader in
>transonic research at the time, and tested Spits, Tempests, P51s,
>P47s,P38s why should only the Spis result be wrong?
Stipulated that he was the world leader at the time. So was the astronomer
Ptolomy. He didn't get it right. The history of science is chock-a-block
with great minds who established fundemental truths later found to be wrong.
>Also, although the P47 had phenomenal acceleration going downhill its
>limiting Mach number was less than a P51
I think you're thinking critical mach number. "Limiting mach number" is a
rather fuzzy concept. While the P-47 had a lower Mcrit than the P-51, it
achieved higher speeds (both in a dive and in modified form, level flight).
R / John
Geoffrey Sinclair
news:M6adnV7VQcWwhDDV...@bt.com...
> Recently read a bit about Spitfire PR Mk XI (EN 409) used for diving
> trials
> which clocked up 606 mph before losing its prop and reduction gear. It
> landed safely after a 20 mile glide.
>
> About a year later, 7/4/45, from what I have read, it force landed at
> Spanish Point, Miltown Malbay in County Clare on the west coast of the
> Irish
> Republic. It was being flown by Canadian pilot F/O Edward Andrew Miller,
> who
> was, quote, "on recce mission over German flying bomb sites".
>
> What puzzles me is:
>
> (1) if he was on a recce over V.1 sites why did he force land 500 or so
> miles away in Eire ?
> (2) what was the purpose of the mission given that V.1 sites had fallen
> into Allied hands 9 months earlier ?
> (3) Given that Eire was neutral, what happend to both a/c and pilot ?
According to the details in Morgan and Shacklady,
EN409, sent to Farnborough 21 April 1943, and used for trials there
and at Boscombe Down, the famed high speed dive was on 27 April
1944. Ended up at number 6 Maintenance Unit in January 1945, by
the looks of it via Heston Aircraft, issued to 8 OTU on 7 February
1945, failed to return 7 April 1945.
Then a web search on 8 OTU,
8 OTU was apparently based in Brawdy, Wales in April 1945,
effectively on the Irish Sea.
So it is clear the pilot was on a training mission, and overshot his
base upon return. If you look up the locations of the places in
question it is a good approximation of a straight line between
Calais, Brawdy (near Pembroke Dock) and Miltown Malbay,
on the Atlantic Coast of Ireland. I would say the pilot missed
crossing the Irish Sea and assumed the west coast of Ireland
was the west coast of the UK.
The aircraft was wrecked it seems, no information on the pilot
but given the war situation I doubt he was held in Ireland for
any length of time if he survived the crash.
Geoffrey Sinclair
Remove the nb for email.
Geoffrey Sinclair
>> That's easy; for a given altitude or airspeed there is a known air
>> pressure measured in inches or millimeters of mercury. Take into account
>> temperature and you can predict true air speed and mach.
>
> BUT, there are compressibility effects in the pitot static system. While
> mach is computable from temperature for a given true air speed, you can't
> derive the aircraft's TAS with a faulty pitot-static system. Most modern
> A/C have an ADC which corrects IAS. Some evidently don't ... the T-45C
> being an example. I doubt any did in WW2.
EN409,
Pitot head removed under the wing and moved to the wing tip,
a pitot comb with 19 heads was mounted behind the wing trailing
edge, reporting airspeeds to a bank of air speed indicators in the
fuselage, the instruments being photographed every 1 to 1.5
seconds.
The Spitfire was climbed to 40,000 feet, accelerated to its
maximum speed and then put into a 45 degree dive under
maximum permissible continuous boost. The aircraft was
recorded as making mach 0.89 at 29,000 feet.
EN409, which came back from a February dive
with popped wing rivets. On 27 April 1944 it was dived to
measure the differences between leading edge pitot-static,
underwing pitot-static and static vent in a high mach dive.
Climbed to 40,000 feet with the altimeter at 1,103, worked
up to 170mph IAS and was dived. At 27,000 feet there was
a loud explosion. Oil on the windscreen blocked any sort of
forward view. There was no propeller and "bits of the engine
were sticking out". The pilot decided to try and save the
aircraft and photographs, finding the gliding characteristics
quite good without a propeller. Making it back for a wheels
down landing at Farnborough. The pilot was Squadron
Leader A F Martindale.
600 mph ASA is mentioned as the maximum speed.
They put up a plinth at Farnborough to mark the event.
Jim Wilkins
wrote:
...
> Pitot head removed under the wing and moved to the wing tip,
> a pitot comb with 19 heads was mounted behind the wing trailing
> edge, reporting airspeeds to a bank of air speed indicators in the
> fuselage, the instruments being photographed every 1 to 1.5
> seconds.
>
> The Spitfire was climbed to 40,000 feet, accelerated to its
> maximum speed and then put into a 45 degree dive under
> maximum permissible continuous boost. The aircraft was
> recorded as making mach 0.89 at 29,000 feet.
>
Wasn't the claimed speed based on rate of change in altitude?
Keith Willshaw
Not as such. From his books its clear that the RAE were
increasingly targetting compressibility problems from 1944
onwards. Not only did discovering the limiting mach number
become an important part of ordinary testing but the preliminary
work being done for Specifcation E24/43, which called for an
aircraft capable of 1,000 mph at 36,000 ft, required a much
better understanding of transonic flow.
Keith
Keith Willshaw
"Geoffrey Sinclair" <gsinc...@froggy.com.au> wrote in message
news:48aeb314$0$1353$5a62...@per-qv1-newsreader-01.iinet.net.au...
The pilot was also injured so by the time he got out of hospital
the war was over.
Keith
Keith Willshaw
Well for one thing they could have tracked the test aircraft on radar
> Interestingly enough, no prop aircraft has ever attempted the absolute
> speed record at altitude.
>
> An OBTW, the high-speed Spit never entered the arena, couldn't begin to
> match the Me-209's 469mph (a one-off, almost an engine with the pilot
> attached to the accessory section).
In level flight it couldnt thats true
> Currently the record is 528.3 mph ... them props have their limitations,
> but without them, no thrust and no speed.
>
Squadron Leader Whittle believes he has an answer :)
Keith
Dudley Henriques
rectifying the .89 without a huge tip drag on the Rotol.
--
Dudley Henriques
John Carrier
>> I know. I just respectfully suggest that the level of ignorance about
>> transonic effects and compressibility was such at the time that errors
>> were likely made. How would they KNOW their machmeter was accurate?
>> There were no supersonic wind tunnels. There were no supersonic
>> aircraft. To put it into perspective, they don't acknowledge speed
>> records based on aircraft instrumentation, they base the record on the
>> time it takes the aircraft to cover a specified course. Everything else
>> is anecdotal.
>>
>
> Well for one thing they could have tracked the test aircraft on radar
Which isn't terribly accurate (particularly in the 1940's) and doesn't
account for wind. There's a reason speed records require two runs (4 for
the low level course) in opposite directions.
R / John
frank
No you can use instrumentation data inside the aircraft, or optical
ground based data, or RADAR data. Instrumentation data on the aircraft
is a sealed system that is tamperproof. You can TM it down to the
ground but for record purposes, its checked on takeoff and usually
again on landing that hasn't been tinkered with.
You can use a speed course, but for a lot of modern stuff, its done in
some airspace, usually Edwards or Utah or Nevada that had telemetry
and all that to track it. Not to mention weather guys to get the
weather data to do all the calculations to get equivalent and true
airspeed.
John Carrier
"frank" <dhssres...@netscape.net> wrote in message
news:09dc191e-0975-4b79...@e53g2000hsa.googlegroups.com...
Sure you can. But we're talking 1944. If you used the word "telemetry" in
1944, the engineers' response would be, "HUH?"
R / John
Geoffrey Sinclair
> Geoffrey Sinclair wrote:
(snip)
>> The Spitfire was climbed to 40,000 feet, accelerated to its
>> maximum speed and then put into a 45 degree dive under
>> maximum permissible continuous boost. The aircraft was
>> recorded as making mach 0.89 at 29,000 feet.
>>
>> EN409, which came back from a February dive
>> with popped wing rivets. On 27 April 1944 it was dived to
>> measure the differences between leading edge pitot-static,
>> underwing pitot-static and static vent in a high mach dive.
>> Climbed to 40,000 feet with the altimeter at 1,103, worked
>> up to 170mph IAS and was dived. At 27,000 feet there was
>> a loud explosion. Oil on the windscreen blocked any sort of
>> forward view. There was no propeller and "bits of the engine
>> were sticking out". The pilot decided to try and save the
>> aircraft and photographs, finding the gliding characteristics
>> quite good without a propeller. Making it back for a wheels
>> down landing at Farnborough. The pilot was Squadron
>> Leader A F Martindale.
>>
>> 600 mph ASA is mentioned as the maximum speed.
>>
>> They put up a plinth at Farnborough to mark the event.
> Maximum boost would indicate the prop full forward. I've having trouble
> rectifying the .89 without a huge tip drag on the Rotol.
I am presuming the engine blew up because the propeller simply
refused to rotate as fast as the engine wanted. So there was
plenty of drag present.
Unfortunately all I have is the summary I have provided. I am unsure
if the pilot had begun to throttle back, he did state he was beginning
to think of easing out of the dive.
Jurassic Park
> http://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Spitfire_XI_...
>
> On April 27, 1944 Sqn. Ldr. Martindale flew a modified Spitfire Mk.XI
> (Nr EN 409) in a 45o dive to achieve 606 mph. He lost the plane's
> modified prop and had to glide her back to base for 20 miles!
Maybe it could be of some interest for you that some sources
http://en.wikipedia.org/wiki/Reggiane_Re_2005
http://www.nationmaster.com/encyclopedia/Reggiane-Re.2005
http://www.aviastar.org/air/italy/reggiane_sagittario.php
report a Reggiane Re-2005 flown by Commander Tullio De Prato in a dive
at 980 Kmh.
Of course the problems about measuring speed were the same for Italian
aircrafts too.
Carlo "Jurassic Park"
frank
> "frank" <dhssresearc...@netscape.net> wrote in message
Weren't they doing photos of the instrument panel? Not sure when they
started doing that, some of the mid 40s were recorded that way.
I know Edwards had after the war some Askania cameras with the
Luftwaffe markings on it. Spoils of war. That was ground photo of
aircraft tracking, later went to Contraves. Though maps still have
Askania sites marked, A-1, whatever. Contraves are C-1, c-2, etc etc.
Would have loved to have a midnight requisition of one of them. Not
sure what the brake test cameras were, were sited along runway, fixed
locations. They finally mowed the damn tumbleweed between camera and
runway which improved data. Or disced it. Probably violated some
California environmental laws....
Dudley Henriques
up with a full feathering Rotol. If so, the idea wasn't all that bad. I
forget what the pitch stops were on the regular Spit Rotol.
On our P51, our 24D50 Hamilton Standard had a governed range of
23degrees against the low pitch stop to 65 degrees against the high
pitch stop.
If you do a high speed dive in these fighters with a constant speed
prop, as the sum of the velocities increase during the dive, the
governor tries to increase the pitch to stay at whatever RPM you've set.
(Don't know where the Brits considered their RPM to be optimumally set
for the start of these dives.)
The prop will increase in pitch until it reaches the high pitch stops,
in the Mustang, this will happen at 65 degrees. The prop AOA is very
high in this area. Now the prop becomes simply a fixed pitch propeller
and as the aeros add up, the prop WILL over speed.
So whatever you do in a high mach dive with a prop fighter, you will
either reach Mcrit for the airplane, (.77 for the P51) or you will over
speed the propeller. Which happens first depends of various factors but
they certainly will happen.
I don't see any way at all that a Spitfire with it's lighter gross
weight, could have reached the extremely high mach numbers cited in the
reports.
I wouldn't blame this on the Brits either. I believe their tests
reflected the best technology of the day. I just can't see that Rotol on
the front of a Spit making it to this high a Mach number before the tip
speeds or Mcrit tore the airplane apart.
--
Dudley Henriques
Keith Willshaw
> Snip
>
>>> I know. I just respectfully suggest that the level of ignorance about
>>> transonic effects and compressibility was such at the time that errors
>>> were likely made. How would they KNOW their machmeter was accurate?
>>> There were no supersonic wind tunnels. There were no supersonic
>>> aircraft. To put it into perspective, they don't acknowledge speed
>>> records based on aircraft instrumentation, they base the record on the
>>> time it takes the aircraft to cover a specified course. Everything else
>>> is anecdotal.
>>>
>>
>> Well for one thing they could have tracked the test aircraft on radar
>
> Which isn't terribly accurate (particularly in the 1940's) and doesn't
Centimetric radar was rather accurate as it happens, good enough to
be used to track the X-1 flights for example. For an SCR-584 the typical
accuracy was about 25 yards distance and 1 mil angle at 18 miles.
Keith
John Carrier
Uh huh. And of course, it was calibrated to allow for the prevailing winds
in 100' altitude increments. You missed my point, Keith. And did that
radar exist when, much less was it used to track, the alleged .92IMN 600mph
flight took place?
R / John
Keith Willshaw
Well yes, centimetric radar was based on the cavity magnetron invented
in the UK and manufactured in the USA. The SCR-584 was a US radar
that entered service in 1943. The RAF equivalent was the type 14 also
used by the RN as the type 277
I find it rather amusing that you assume there was some major breakthrough
that allowed accurate measurement of mach numbers in 1947
while it was impossible in 1944. I somehow doubt they accurately
measured temperatures at 100ft height intervals over Muroc when
the X-1 made its first supersonic flight. I do however know they had
radar tracking in place.
Keith
LIBERATOR
> http://upload.wikimedia.org/wikipedia/commons/thumb/9/94/Spitfire_XI_...
>
> On April 27, 1944 Sqn. Ldr. Martindale flew a modified Spitfire Mk.XI
> (Nr EN 409) in a 45o dive to achieve 606 mph. He lost the plane's
> modified prop and had to glide her back to base for 20 miles!
>
That would have caught the ME262.
LIBERATOR
> >news:g8kqeo$9m3$1$8300...@news.demon.co.uk...
> >> "John Carrier" <j...@comcast.net> wrote in message
That seems like a lot of variances allocating error, Dannyboy, are you
sure about this?
guy
> "Keith Willshaw" <keithnos...@demon.co.uk> wrote in message
>
> news:g8ujbg$rjv$1$8302...@news.demon.co.uk...
>
>
>
>
>
>
>
> > "John Carrier" <j...@comcast.net> wrote in message
>
> - Show quoted text -
You fail to answer my query, why do you accept all the Mach numbers
quoted for other aeroplanes except the Spit?
Guy
John Carrier
"guy" <guyswe...@googlemail.com> wrote in message
news:48259b39-d80e-4e40...@m73g2000hsh.googlegroups.com...
Because as an aero engineeer who has some familiarity with the problems of
transonic and supersonic flight, I consider .8 IMN achievable and .92 not so
in similar aircraft. The Spit was not sufficiently superior (if superior at
all) to other aircraft that achieved far lesser speeds. Propellers don't
produce thrust at the speeds described and gravity isn't sufficient to
overcome the drag associated with normal shock wave formation.
R / John
Die Whigphilosophie der Geschichte im Hefeweizen
wrote:
>The Spit was not sufficiently superior (if superior at
>all) to other aircraft that achieved far lesser speeds.
Maybe not, but then an explanation involving the necessary relative
aerodynamic advantage on the Spitfire's part to account for this has
been advanced.
Gavin Bailey
--
"I've never seen as motley a collection of bald faced outrageous liars and
gibbering, irrational apes as Democrats." - Stuart Grey
Dudley Henriques
The Spit was and is for that matter, a fine airplane. The ultimate
answer to the .92 question lies in the time line of the dives. The
question is quite simple really. The beginning altitude of the dive
determines a specific time parameter where .92 has to be acheived
leaving altitude for recovery considering available radial g for the
airplane.
During this available time line, a prop fighter (ANY prop fighter) has
to accelerate to the required mach number and recover.
Accelerating in the dive assuming a propeller is involved, reveals
another time line; that for the propeller to hit the high pitch stop and
pitch no further. At this point the propeller becomes subject to
aerodynamic helix factors including tip speed, drag curve, and
eventually shock wave formation.
As all this is happening, the airplane's individual Mcrit becomes a factor.
The time line, considering these factors will determine whether a prop
fighter CAN achieve a specific mach number in a dive before recovery is
required.
I don't have the figures in front of me for the Rotol, but I'd be amazed
if a Rotol prop installed on a Spit, even a special prop set up for a
full feather would allow, considering all helix velocities, delayed
shock that allowed a .92 mach number. If the dive was begun with the
prop feathered, not enough acceleration on the time line. If the dive
started with the prop governor in play, I just don't see enough time to
go to .92 before the prop hit the stops and went aerodynamic.
I can't explain the Brits claim, and certainly the pilots involved were
the best around, but I just don't see a Spit at .92 and still in one
piece.
--
Dudley Henriques
Die Whigphilosophie der Geschichte im Hefeweizen
<dhenr...@rcn.com> wrote:
>I can't explain the Brits claim, and certainly the pilots involved were
>the best around, but I just don't see a Spit at .92 and still in one
>piece.
It wasn't, though. The range for ones returning in one piece appears
to be 0.86-0.89.
Gavin Bailey
--
"You gibber. You deny your own stupid argument. As a human, you're a
failed experiment, lacking both reason and intelligence." - Stuart Grey
Dudley Henriques
> <dhenr...@rcn.com> wrote:
>
>> I can't explain the Brits claim, and certainly the pilots involved were
>> the best around, but I just don't see a Spit at .92 and still in one
>> piece.
>
> It wasn't, though. The range for ones returning in one piece appears
> to be 0.86-0.89.
>
> Gavin Bailey
I can't actually recall where I saw the .92 number mentioned; somewhere
in the many posts over time on this issue.(remember I'm not a historian :-)
I have to say though, strictly from a pilot's viewpoint, even .86 to .89
seems really a bit high to me. I've never done any serious research
into the issue and I'll read up on it a bit more.
The Mustang was a very clean airplane and I've had one way out there
mach wise, but a 51 couldn't get anywhere near the numbers mentioned
here without severe consequences. .77 or 505mph for the Mustang.
--
Dudley Henriques
Keith Willshaw
> I don't have the figures in front of me for the Rotol, but I'd be amazed
> if a Rotol prop installed on a Spit, even a special prop set up for a full
> feather would allow, considering all helix velocities, delayed shock that
> allowed a .92 mach number. If the dive was begun with the prop feathered,
> not enough acceleration on the time line. If the dive started with the
> prop governor in play, I just don't see enough time to go to .92 before
> the prop hit the stops and went aerodynamic.
>
> I can't explain the Brits claim, and certainly the pilots involved were
> the best around, but I just don't see a Spit at .92 and still in one
> piece.
>
The account given in 'The Concorde Story' was that they used a Spifire
PR Mark XI fitted with a Merlin 70 engine. The power dive was started from
40,000 ft and the aircraft descended in a 45 degree dive. Mach 0.9
was reached as the aircraft passed through 29,000 ft.
Keith
Dudley Henriques
Hi Keith;
What is interesting to me, and always has been a question of mine about
ALL the high mach dives including the dives by Herb Fisher in the Jug
was where they set the prop before starting the dive.
For me, the prop setting has always been a critical issue as to how far
anyone actually got into the transonic zone. I could kick myself for not
asking Fisher before he died. The subject simply never came up in our
conversations together. :-(
If you ever come up with this data, I'd appreciate having the answer.
I know that the Brits experimented with a full feathering Rotol in an
attempt to solve the governor problem, but I've never heard how these
tests actually turned out.
--
Dudley Henriques
John Carrier
Quite advanced fire control radars, particularly in their day. And while
they might well be capable of reporting a fairly accurate ground speed,
airspeed is another matter. I have flown an A-4 (subsonic aircraft) cross
country in which I was indicating .75 (cruise mach at 41K). Ground speed,
as measured by ATC was 680KIAS (nice jet stream that day). A ground fire
control radar cannot accurately report the airspeed of the aircraft in a
moving fluid.
> I find it rather amusing that you assume there was some major breakthrough
> that allowed accurate measurement of mach numbers in 1947
> while it was impossible in 1944. I somehow doubt they accurately
> measured temperatures at 100ft height intervals over Muroc when
> the X-1 made its first supersonic flight. I do however know they had
> radar tracking in place.
No major breakthroughs. Slow and gradual accumulation of knowledge. And
just one more time, a ground based tracking radar, no matter how wonderful
it might be, CANNOT accurately measure mach or airspeed. That takes the
aircraft's instrumentation and uncorrected, it's subject to error; which
gives rise to the 700mph Thunderbolt (later corrected to 550) and evidently
the 600mph Spitfire.
Temperature measurement is done on the aircraft through a total temperature
sensor. I'm sure the test Spit had such a device. The XS-1 did. I think 3
years of progress allowed the XS-1 to have a significantly more accurate
machmeter. Feel free to cherish you own opinion.
Most, not all, modern aircraft have an air data computer to correct for a
variety of errors within the pitot static system. Not so during WW2.
R / John
guy
> "guy" <guyswetten...@googlemail.com> wrote in message
While you undoubtedley know more about transonic aerodynamics than me
I still do not understand why ***only*** the figures for the spit are
disputed, and also why they have been accepted until now.
Guy
Keith Willshaw
A little more than fire control radars
> And while they might well be capable of reporting a fairly accurate ground
> speed, airspeed is another matter. I have flown an A-4 (subsonic
> aircraft) cross country in which I was indicating .75 (cruise mach at
> 41K). Ground speed, as measured by ATC was 680KIAS (nice jet stream that
> day). A ground fire control radar cannot accurately report the airspeed
> of the aircraft in a moving fluid.
>
Indeed but it can act as a good sanity check.
>> I find it rather amusing that you assume there was some major
>> breakthrough
>> that allowed accurate measurement of mach numbers in 1947
>> while it was impossible in 1944. I somehow doubt they accurately
>> measured temperatures at 100ft height intervals over Muroc when
>> the X-1 made its first supersonic flight. I do however know they had
>> radar tracking in place.
>
> No major breakthroughs. Slow and gradual accumulation of knowledge. And
> just one more time, a ground based tracking radar, no matter how wonderful
> it might be, CANNOT accurately measure mach or airspeed. That takes the
> aircraft's instrumentation and uncorrected, it's subject to error; which
> gives rise to the 700mph Thunderbolt (later corrected to 550) and
> evidently the 600mph Spitfire.
>
Trouble is as both the test pilot concerned and Mr Sinclair posted the
Spitfire
concerned did have an accurate temperature corrected machmeter
with multiple static ports in a pitot comb on the trailing edge. Indeed
the main purpose of the test we are discussing was to investigate
the performace of different pitot static devices.
> Temperature measurement is done on the aircraft through a total
> temperature sensor. I'm sure the test Spit had such a device. The XS-1
> did. I think 3 years of progress allowed the XS-1 to have a significantly
> more accurate machmeter. Feel free to cherish you own opinion.
>
An assertion with no evidence to back it
> Most, not all, modern aircraft have an air data computer to correct for a
> variety of errors within the pitot static system. Not so during WW2.
>
Keith
Die Whigphilosophie der Geschichte im Hefeweizen
<dhenr...@rcn.com> wrote:
>I can't actually recall where I saw the .92 number mentioned; somewhere
>in the many posts over time on this issue.(remember I'm not a historian :-)
>I have to say though, strictly from a pilot's viewpoint, even .86 to .89
> seems really a bit high to me. I've never done any serious research
>into the issue and I'll read up on it a bit more.
>The Mustang was a very clean airplane and I've had one way out there
>mach wise, but a 51 couldn't get anywhere near the numbers mentioned
>here without severe consequences. .77 or 505mph for the Mustang.
There are two issues being conflated here, though - the accuracy of
the RAE test figures for Martingdale's flight, and the relative
capacity for the Spitfire to achieve high mach numbers compared to
other aircraft.
On the first, I can't comment, but if the RAE figures are out, it
would be reasonable to suppose they were out by a similar factor on
all the other compressibility measurement flights they were making at
the same time. Assuming no deliberate trickery on the Spit flight
alone, it still leaves us with the Spit achieving a higher mach number
than the other aircraft (P-38, P-47 and P-51) involved. There is a
credible argument to explain this on the basis of the Spitfire's
better wing thickness/chord ratio, although I have no idea if it's
actually correct. It certainly had a better transonic wing than the
laminar-flow winged Spitful which followed it.
FWIW the RAE figures for the Mustang were 0.80. This was a Mustang I,
though and I think reaching the same height as the Spit XI would be
questionable (apparently the dive was commenced from 28,000 ft rather
than 40,000 ft) even if the airframe was fractionally cleaner than the
Merlin-engined variants. The Spit could enter the dive from a lot
higher and at a much higher TAS.
Gavin Bailey
--
I have enough of Windows error message which say "Intelligent life
not detected at keyboard." You hear me good Bill! Not mess Eastern
devil warrior. Yeah like Jackie Chan. Worse Bart Kwan-En.
- Bart Kwan En
Dudley Henriques
usually try and stay out of these "this plane did this and that plane
did this" things. :-) I can't address the Spit issue having not done any
high speed diving in a Spitfire, but I can tell you from personal
experience that diving a P51 deeply into compressibility is no fun.
North American did dive testing on the Mustang to .80 and modified the
elevator angle of incidence on the horizontal stabilizers of the D to
deal with the porpoise problem at high mach numbers.
I took a Mustang out only to a little over .70 and had a severe tuck
issue, and we're not even talking about the prop yet :-)
What's amazing to me about all this talk going on about these dives is
no one seems to be talking about the propeller issues except me. The
role of the propeller in high speed diving is critical. In maxing out a
high mach dive in a prop fighter, you will either reach Mcrit for the
airplane or reach the aerodynamic helix limits for the propeller or
both. Whatever mach number you have when these things hit the fan (no
pun intended) is it for that aircraft.
It appears to me that reaching the prop limit was what happened to
Martindale. At what mach number this occurred I have no idea.
Not related to the Spitfire of course but .70 in a Mustang was no picnic
:-))
--
Dudley Henriques
John Carrier
>While you undoubtedley know more about transonic aerodynamics than me
>I still do not understand why ***only*** the figures for the spit are
>disputed, and also why they have been accepted until now.
Well, if someone said the Spit made .80-.85 I'd readily believe them.
That's about Mcrit for every WW2 but still plausible and reachable given the
nature of transonic drag rise. .92/600mph is a NOT plausible. The drag
increase as shock waves grow larger isn't small, but rather several times
subsonic drag coefficients. Takes a lot of power to bludgeon through it and
with essentially no power from the engine and its prop, gravity isn't
enough.
R / John
Die Whigphilosophie der Geschichte im Hefeweizen
<dhenr...@rcn.com> wrote:
>I'll tell you the truth. Not being any kind of credible historian I
>usually try and stay out of these "this plane did this and that plane
>did this" things. :-)
Sure, but as a (hopefully) credible historian, I think it's possible
to evaluate the sources and reach a defensible conclusion. I suspect
the 0.92 flight may be exaggerated, although based on the Machmeter
readings at the time. This wasn't simply a case of pilots having a
beer over an exceptional experience - RAE were a responsible body
conducting credible scientific experimentation into the transonic
behaviour of the relevant fighter types.
Jefrey Quill referred to these tests indicating that the Spitfires had
a corrected critical Mach number of 'a shade under' 0.9, which I
imagine is the significant qualification.
>I can't address the Spit issue having not done any
>high speed diving in a Spitfire, but I can tell you from personal
>experience that diving a P51 deeply into compressibility is no fun.
Brown's description of the experience would certainly agree with
yours, describing tail-shaking of increasing violence and
nose-dropping starting at 0.83 in the dive, followed by rolling with
increasing stick forces required to prevent the angle of dive
increasing. Brown referred to these being 60lbs at 0.86, and this
being his 'physical limit' with both hands on the stick.
>What's amazing to me about all this talk going on about these dives is
>no one seems to be talking about the propeller issues except me. The
>role of the propeller in high speed diving is critical. In maxing out a
>high mach dive in a prop fighter, you will either reach Mcrit for the
>airplane or reach the aerodynamic helix limits for the propeller or
>both. Whatever mach number you have when these things hit the fan (no
>pun intended) is it for that aircraft.
>It appears to me that reaching the prop limit was what happened to
>Martindale. At what mach number this occurred I have no idea.
I suppose some of this is really an argument about what the CSU and
reduction gear can stand - I have to admit I assumed the prop would
hit a governed limit at some point..
>Not related to the Spitfire of course but .70 in a Mustang was no picnic
>:-)
I'll leave that sort of thing for you and Martindale to find out,
thanks.
Gavin Bailey
--
Fochinell
"Ancient Scots warcry" painted on the side of a Spitfire Mk XIV
- presumably without Air Ministry approval.
Dudley Henriques
solid. Whatever they reported, I would bet the farm they honestly
believed, based on the available data, instrumentation, and (telemetry
if there was any)
Brown and Quill were both top notch no nonsense pilots. I just wouldn't
believe either would falsify a report.
If there was a discrepancy in the figures, it would come from the data
accumulation process in my humble opinion anyway.
In thinking it over as far as technique is concerned, I make the game a
simple one really. Can the aircraft in question make it to the stated
Mach number in a dive, given the altitude available, the Mcrit for the
airframe, the helix velocity limits for the prop with the high pitch
stops considered, then affect the dive recovery in the available radial
g from that Mach number.
.80 seems reasonable for the parameters, but I just can't see going much
deeper without severe problems.
But remember, I'm only dealing here with a stock airplane. I have no
idea at all what was done in the way of modifications to these airplanes
to leave them on the dive time line a bit longer.
THAT could be the answer!
--
Dudley Henriques
guy
>
> - Show quoted text -
Dudley, just out of interest what model Mustang did you do your dives
in? (I assume it was a Merlin one?)
also what height did your dives start and at how much height did you
lose in reaching your max mach number?
cheers
Guy
Dudley Henriques
My "dives" consisted of one dive. Had an O2 failure on a cross country
at 25 thousand. Woke up at about .70.
Even at .70 I was getting nose tuck, a walking stick and prop vibration.
It was enough to convince me I didn't want to do it again :-)
--
Dudley Henriques
John Carrier
> solid. Whatever they reported, I would bet the farm they honestly
> believed, based on the available data, instrumentation, and (telemetry if
> there was any)
> Brown and Quill were both top notch no nonsense pilots. I just wouldn't
> believe either would falsify a report.
> If there was a discrepancy in the figures, it would come from the data
> accumulation process in my humble opinion anyway.
If any readers feel I was implying the aviators involved were exaggerating
what they saw, please accept my apology. I have no doubt they reported what
they witnessed accurately. I just don't believe the instrumentation was
sufficiently developed or accurate enough and resulted in exaggerated
readings. There are those who differ in their opinion, we must therefor to
agree to disagree.
Whether or not the Spit attained the speed described is immaterial. It was
the best aircraft over Great Britain in the summer of 1940 and the
outnumbered but brave souls who flew her not only experienced "their finest
hour" but arguably the finest hour in the history of fighter aviation.
R / John
Dudley Henriques
This reader for one, never even entertained that thought about you and
I'd be sadly disappointed to find out that anyone here who knows you and
your involvement in fighter aviation entertained that thought as well.
--
Dudley Henriques
Die Whigphilosophie der Geschichte im Hefeweizen
<dhenr...@rcn.com> wrote:
>What's amazing to me about all this talk going on about these dives is
>no one seems to be talking about the propeller issues except me. The
>role of the propeller in high speed diving is critical.
Quill does mention that Martindale's aircraft had a fully-feathering
Rotol prop to prevent overspeeding.
Die Whigphilosophie der Geschichte im Hefeweizen
wrote:
>Whether or not the Spit attained the speed described is immaterial. It was
>the best aircraft over Great Britain in the summer of 1940 and the
>outnumbered but brave souls who flew her not only experienced "their finest
>hour" but arguably the finest hour in the history of fighter aviation.
The point I would make is that other authoritative commentators had
described Martindale's 0.92 as something more like 0.89 after
correction, but this still amounted to something significantly better
than the other contemporary types tested. As I said, the RAE weren't
a group of pilots shooting the breeze in the mess at night. It's also
worth remembering that the Spitfire certainly had better transonic
controllability than the first generation jets.
In terms of absolute and controllable speeds in transonic dives, a
substantive aeodynamic differential in the Spitfire's favour did
exist, which helps explain why the career of the Spitfire as a
competitive first-line interceptor didn't begin and end in 1940.
Geoffrey Sinclair
>> I agree completely that the word of the Brit pilots should be considered
>> solid. Whatever they reported, I would bet the farm they honestly
>> believed, based on the available data, instrumentation, and (telemetry if
>> there was any)
>> Brown and Quill were both top notch no nonsense pilots. I just wouldn't
>> believe either would falsify a report.
>> If there was a discrepancy in the figures, it would come from the data
>> accumulation process in my humble opinion anyway.
>
> If any readers feel I was implying the aviators involved were exaggerating
> what they saw, please accept my apology.
I would be surprised if someone thought that.
> I have no doubt they reported what they witnessed accurately. I just
> don't believe the instrumentation was sufficiently developed or accurate
> enough and resulted in exaggerated readings. There are those who differ
> in their opinion, we must therefor to agree to disagree.
If a WWII propeller fighter did do 600 mph this appears to be the
attempt most likely to be verifiable or not. It comes after a series
of tests and with aircraft modified to record the speeds.
Before its April dive EN409 had come back from a dive in
February with a large number of popped wing rivets.
The April dive started at 40,000 feet (altimeter set at 1,013),
2850 rpm, 170 mph IAS, he bunted into the dive then slightly
closed the throttle. The 19 head pitot comb was 16.5 inches
high, and attached to the starboard wing trailing edge so it
was at 98 inches from the aircraft centre line and so that some
of the heads were above the wing and some below, all heads
being 12 inches (or 0.133 chords) behind the wing trailing edge.
The twin supports holding the comb to the wing were spread
widely to ensure their turbulence did not effect the measurements,
the outboard attachment was basically beside the aileron.
The starboard wing leading edge outboard of the aileron had a
vane for measuring incidence, the port wing had a pitot static
head again outboard of the aileron.
The trials concluded to record true mach numbers the pitot
heads needed to be installed close to the wing leading edge.
The objective was to measure wing profile drag.
A 15 August dive in PL827 resulted in the engine over speeding,
probably because of the failure of the constant speed unit, the
supercharger caught fire, Martindale was the pilot again and he
managed to crash land and save the photographs but injured his
spine.
Spitfire XI PL827 had a series of 1/16 holes drilled into its wings at
98 inches from the centreline, 10 in the upper and 10 in the lower
wing surfaces, none forward of the main spar. A further 4 holes were
drilled in the upper and 4 in the lower inner wing surfaces near the
trailing edge. The pressure was then measured at these points. The
results were no flow separation up to Mach 0.85 and at that speed
supersonic airflows in the region of the upper wing covered more than
half the chord, which was 89.6 inches at that point.
Geoffrey Sinclair
Remove the nb for email.
Dudley Henriques
> <dhenr...@rcn.com> wrote:
>
>> What's amazing to me about all this talk going on about these dives is
>> no one seems to be talking about the propeller issues except me. The
>> role of the propeller in high speed diving is critical.
>
> Quill does mention that Martindale's aircraft had a fully-feathering
> Rotol prop to prevent overspeeding.
>
> Gavin Bailey
>
pertaining to this discussion.
--
Dudley Henriques