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Certainly there were warnings to German pilots that if a yaw developed in a dive the wing tips tended to come off. Instructions were given that the wing tips should be checked so it would appear that the weakness is one that would build up over time, as opposed to one off catastrophic failures
The zero sink rate flight speed of a clean 51D is about 110 IAS - which means at that speed it loses no altitude in level flight.
The Stall speed - clean- is about 80 +/- IAS.
Certainly there were warnings to German pilots that if a yaw developed in a dive the wing tips tended to come off. Instructions were given that the wing tips should be checked so it would appear that the weakness is one that would build up over time, as opposed to one off catastrophic failures
As a structures guy I want the main spar as close as possible to the Center of Lift- nominally at 25%, so that I am not adding a Lift Force to the existing Moment by moving the main spar, to say at 45% Chord, away from Center of lift.. like the 109.
my guess is its lower though
AFAIK,
This does not show up in any of the high speed trials. That being said, any of these aircraft will suffer catastrophic structural failure if the limits are exceeded.
Hence we see the P51, Spitfire, and Bf-109 structural failures.
Crumpp
The FW-190A8's is about 110mph. The stall speed I used in my analysis are 89.5KEAS for the P51 and 94.4KEAS for the FW-190A8.
All the Best,
Crumpp
Re the reference to the wing tip failures, it was part of the Technical Instructions from Generalluftzeugmeister Berlin, 28th August 1942 so I have no reason to doubt its accuracy.
The Bf-109 developed a Dutch roll. A common stability issue even today. Fly a Pitts S-1 if you want to see some good Dutch roll.
Crumpp
This would imply to me that it was a more common problem on the 109 as this was a general warning issued to all units.
I am not aware of similar warnings being sent to all Spitfire or P51 units.
Certainly I could be wrong on this and if anyone has a similar warning issued to allied units, I am happy to change my view.
Exactly at what alt is this Bill and from where do you have this ??
The reason I'm asking is because the official figures are much higher.
This is from the POH:
"Official" ??
As you can see the P-51D's stall speed in level flight was around 106 mph clean.
at 10,000 feet, 96 at 8,000 close to 80 at SL
I don't have the official figure for the FW-190, I was hoping Crumpp would provide that, my guess is its lower though, esp. considering the much shorter take off run and distance to clear a 20m high object.
The Center of Lift is located at the main wing spar in the Bf-109G. I can send you the ladeplan and the Ersatzteilliste. You might be thinking of the rearward CG limit. Remember that has to be just forward CoL if we want a controllable aircraft.
All the best,
Crumpp
... that`s a faulty conclusion based on insufficent information. We know there was an instruction for the 109F wingtips. Do we know the 109G still had this problem? How we do the Mustang and Spitfire (La7, Yak3, Typhoon etc.) did not have similiar problems? They are less well documented? Of course. The less details we dig up on a plane, the fewer skeletons we find in the cupboard. But that doesn`t effect the actual number of skeletons overall. They are there, even if we don`t know about it.
BTW, ever wondered why the 'pointed', ie. tall vertical stabiliser was introduced to the Spitfire..? Stabiliser fin to the p51d..? Tall tail to the 109?
These aircraft had more in common than not. Designers kept bumping into the same limits, no matter the country. Physics are universal.
Page 29 of the "Pilot's Flight Operating Instructions AN 01-60JD-1" has the reference to Zero Sink speed - clean.
Multiple references are made to this including the instruction to not start climb until flaps are up and airspeed at least 110IAS... and do not side .slip the Mustang below 110 IAS, etc..
Stall speed is contained in Appendix II and varies with load but I have flown the airplane several times at 80-90 mph at 5000 feet to coax it into a clean stall, notably because my dad 'insisted' that I learn how easy it is to recover from. The bird would have weighed in the 8900+ weight range.
You were looking at 106mph/10,000 feet in your Power Off Stall chart and failed to notice (?) that the stall speed in that chart was down to 94 mph for 8,000 feet and continues to drop with increased density.
Crumpp's figures are`'correct' for good assumptions in performance calculations.
Btw, is it me or are you saying you actually fly the P-51 ?? - suspiciously late to come forth with this IMO.
What are you talking about Bill ??!
The stall speeds are given for different weights, NOT different altitudes!
What the chart says is that the P-51D stalls at 106 mph at SL at 9,700 lbs ! At 10,000 lbs its 108 mph at SL. There's no way the P-51D is ever going to fly at 80 mph clean, the real stalling speed is WAY higher than that!
Btw, is it me or are you saying you actually fly the P-51 ?? - suspiciously late to come forth with this IMO.
When your father is a P51 Ace, you think he might take you flying?
All the best,
Crumpp
I made an assumption based on drawings I have seen of the 109 that the main spar is around 45% chord - not so? or, just as intriguing the Center of Lift actually at 45%??
Page 29 of the "Pilot's Flight Operating Instructions AN 01-60JD-1" has the reference to Zero Sink speed - clean.
Multiple references are made to this including the instruction to not start climb until flaps are up and airspeed at least 110IAS... and do not side .slip the Mustang below 110 IAS, etc..
Stall speed is contained in Appendix II and varies with load but I have flown the airplane several times at 80-90 mph at 5000 feet to coax it into a clean stall, notably because my dad 'insisted' that I learn how easy it is to recover from. The bird would have weighed in the 8900+ weight range.
You were looking at 106mph/10,000 feet in your Power Off Stall chart and failed to notice (?) that the stall speed in that chart was down to 94 mph for 8,000 feet and continues to drop with increased density.
(Wrong - I misread the chart - each condition for stall i power Off and different gross weights - called a brain fart on my part
Crumpp's figures are`'correct' for good assumptions in performance calculations.