The sound barrier
- Thread starter Velius
- Start date
Ad: This forum contains affiliate links to products on Amazon and eBay. More information in Terms and rules
kool kitty89
Senior Master Sergeant
http://www.zenoswarbirdvideos.com/Images/Me262/ME262WendeL.pdf
I finished reading through the British article and found no menthin to elevator trim tabs, the rudder tab was mentioned several thimes though. Also, the tailplane trim was mentioned in this article as well.
I finished reading through the British article and found no menthin to elevator trim tabs, the rudder tab was mentioned several thimes though. Also, the tailplane trim was mentioned in this article as well.
kool kitty89
Senior Master Sergeant
Soren, I know the tabs exist, but that doesn't mean they were used.
Accoring to this extensive article on the Me 262's construction: http://www.enginehistory.org/German/Me-262/Me262_Airframe_2.pdf
It mentions that:
In any case, that British pilot's notes on the 1945 tests makes it clear that they were at least aware of the use of the tailplane trim. Indeed, there is no other mention to pitch trim than that pertaining to the variable incedence tailplane. (wether that trim function was used in dives is another issue)
Accoring to this extensive article on the Me 262's construction: http://www.enginehistory.org/German/Me-262/Me262_Airframe_2.pdf
It mentions that:
(the article also mentions the aileron tabs being intended to be of the in flight adjustable servo type, but were simple ground adjusted tabs in practice)
In any case, that British pilot's notes on the 1945 tests makes it clear that they were at least aware of the use of the tailplane trim. Indeed, there is no other mention to pitch trim than that pertaining to the variable incedence tailplane. (wether that trim function was used in dives is another issue)
kool kitty89
Senior Master Sergeant
I believe one of the riveted gusset plates is visible in this immage:
Look closely at the inboard trailing edge of the tab on the right.
And on a somewhat different note:
It should also be noted that, whaile not developed for high Mach number control, both the Bf 109 and Fw 190 featured variable incidence tailplanes. (for trim purposes; I believe the 109's mechanism was very similar to that of the Me 262)
Look closely at the inboard trailing edge of the tab on the right.
And on a somewhat different note:
It should also be noted that, whaile not developed for high Mach number control, both the Bf 109 and Fw 190 featured variable incidence tailplanes. (for trim purposes; I believe the 109's mechanism was very similar to that of the Me 262)
drgondog
Major
Lol - you wish to claim that the 262 reached 1100KM/hr BEFORE compressibility started? You know that is about 593 kts and at SL = .89 Mach and 593 kts~ 95. Mach at 15000 feet, and .98M at 25000ft - at STP?
At what altitude do you propose the 262 ever came close to 1100km/hour? and that Mach number would Be?
Bill the airspeed indicator went off the scale at 1,100 km/h at 36,000 ft, at which altitude the speed of sound is 1,062 km/h. Mutke notes that heavy vibrations started around that time and the a/c started to nose down uncontrollably, until suddenly the vibrations stopped. Mutke then started to recover the dive by shutting the engines and trimming the movable horizontal tail plane, and while pulling up the vibrations suddenly started again, but he managed to pull out and reduce the speed to 500 km/h.
Yep I see it KK, small rectangular plate at the far left trailing edge of the tab(red circle above), they were clearly rivetted in place on that a/c, I agree with that.
But note the servo arms have been removed, unlike on the RAE specimen where they are clearly visible.
drgondog
Major
Soren - in all seriousness no one relies on airspeed indicators for accuracy above .6-.65 M. P-51's were 'recorded' (airspeed indicator) as having reached 660mph in a dive - which is absurd. The highest terminal dive speed for a 51 was in the 505-510mph range at 20,000 feet.
What other reference would support more than say 1000km/hr TAS? That would be ~ . 86 at 15000 and .89 at 25,000 - which looks to be a real problem for that wing/nacelle combo in transonic regime.
I'm not saying the speed readings were accurate Bill, they were obviously too high when the vibrations started cause as noted the speed of sound is below 1,100 km/h at 36,000 ft. However all the characteristics he notes pretty much concludes he went supersonic, and like modern aerodynamical studies have shown it indeed is possible. So I have absolutely no reason not to believe he went supersonic, other than your unsupported claim that he didn't based on a simple hunch.
drgondog
Major
Soren - Then of course you believe Tommy Hayes when he reported that he was doing 660 mph chasing a 109 in a dive because the instruments showed he was close and the Mustang exhibted 'charcteristics' of supersonic transition??
I would not characterize my skepticism on a simple hunch, nor should you exhibit belief based on Mutke's beliefs any more than Hayes.
What is the Cd0 of the 262 versus the F-86? If you say 'studies show' then surely you can dig up the 'studies' that show that the 262 is capable of supersonic speed in a dive.
drgondog
Major
From Wikipedia with following references cited.
"Messerschmitt also conducted a series of flight tests with the series production Me 262. In dive tests, it was determined that the Me 262 went out of control in a dive at Mach 0.86, and that higher Mach numbers would lead to a nose-down trim that could not be countered by the pilot. The resulting steepening of the dive would lead to even higher speeds and disintegration of the airframe due to excessive negative g loads.
Despite the necessity to gain experience in high-speed flight for the HG II and III designs, Messerschmitt undertook no attempts to exceed the Mach 0.86 limit for the Me 262.
After the war, the Royal Aircraft Establishment, at that time one of the leading institutions in high-speed research, re-tested the Me 262 to help with British attempts at exceeding Mach 1. The RAE achieved speeds of up to Mach 0.84 and confirmed the results from the Messerschmitt dive tests. Similar tests were run by the Soviets. No attempts were made to exceed the Mach limit established by Messerschmitt.
"After Willy Messerschmitt's death, the former Me 262 pilot Hans Guido Mutke claimed to be the first person to exceed Mach 1, on 9 April 1945 in a Me 262 in a "straight-down" 90° dive. This claim is disputed because it is only based on Mutke's memory of the incident, which recalls effects other Me 262 pilots observed below the speed of sound at high indicated airspeed, but with no altitude reading required to determine the actual speed. Furthermore, the pitot tube used to measure airspeed in aircraft can give falsely elevated readings as the pressure builds up inside the tube at high speeds. Finally, the Me 262 wing had only a slight sweep incorporated for trim (center of gravity) reasons and likely would have suffered structural failure due to divergence at high transonic speeds. One airframe (Me 262 HG1 V9 WNr130 004 VI+AD [22]) was prepared with the low-profile Rennkabine racing canopy and may have achieved an unofficial record speed of 606 mph, altitude unspecified.[23]"
22 Radinger and Schick 1996, p. 75.
^ Radinger and Schick 1996, pp. 75, 79. Note: Willy Messerschmitt July 1943.
^ Radinger and Schick 1996, p. 79.
^ Radinger and Schick 1996
23^ Flying Review, 1960s, date unkown
What are your sources Soren?
"Messerschmitt also conducted a series of flight tests with the series production Me 262. In dive tests, it was determined that the Me 262 went out of control in a dive at Mach 0.86, and that higher Mach numbers would lead to a nose-down trim that could not be countered by the pilot. The resulting steepening of the dive would lead to even higher speeds and disintegration of the airframe due to excessive negative g loads.
Despite the necessity to gain experience in high-speed flight for the HG II and III designs, Messerschmitt undertook no attempts to exceed the Mach 0.86 limit for the Me 262.
After the war, the Royal Aircraft Establishment, at that time one of the leading institutions in high-speed research, re-tested the Me 262 to help with British attempts at exceeding Mach 1. The RAE achieved speeds of up to Mach 0.84 and confirmed the results from the Messerschmitt dive tests. Similar tests were run by the Soviets. No attempts were made to exceed the Mach limit established by Messerschmitt.
"After Willy Messerschmitt's death, the former Me 262 pilot Hans Guido Mutke claimed to be the first person to exceed Mach 1, on 9 April 1945 in a Me 262 in a "straight-down" 90° dive. This claim is disputed because it is only based on Mutke's memory of the incident, which recalls effects other Me 262 pilots observed below the speed of sound at high indicated airspeed, but with no altitude reading required to determine the actual speed. Furthermore, the pitot tube used to measure airspeed in aircraft can give falsely elevated readings as the pressure builds up inside the tube at high speeds. Finally, the Me 262 wing had only a slight sweep incorporated for trim (center of gravity) reasons and likely would have suffered structural failure due to divergence at high transonic speeds. One airframe (Me 262 HG1 V9 WNr130 004 VI+AD [22]) was prepared with the low-profile Rennkabine racing canopy and may have achieved an unofficial record speed of 606 mph, altitude unspecified.[23]"
22 Radinger and Schick 1996, p. 75.
^ Radinger and Schick 1996, pp. 75, 79. Note: Willy Messerschmitt July 1943.
^ Radinger and Schick 1996, p. 79.
^ Radinger and Schick 1996
23^ Flying Review, 1960s, date unkown
What are your sources Soren?
drgondog
Major
I understand Vicenzo - I have written sections of it myself. The only point I would make is that the references cited are valid.
The 262 was slightly cleaner than a P-80 which was much draggier than an F-86. The F-86 was able to get through the transonic and into supersonic in a dive with no severe stability issues.
Soren would have you believe a 262 could go somewhere between ".89 and .96 Mach" when nothing other than Mutke's 'say so' based on his airspeed indicator with no substantiation other than his post flight claim.
Soren says the 262 can exceed the speed of sound today. Here is the website of Stormbirds - the guys building the 262 around the GE J85 engine
Me 262 PROJECT TECHNICAL DATA
They are REAL clear about Do Not Stress the airplane to 600mph and have it placard at 540mph - that is right in the strikezone for what they describe as the Technical data from Messerschmidt. So guys that are building them and flying them have no preconceived notions that the 262 is more than a .86M aircraft MAXIMUM.
If he wants folks to believe the 262 is 'capable of supersonic' he needs references from engineers and data to back his claim.
kool kitty89
Senior Master Sergeant
The comment on wing sweep on the wikipedia quote really has nothing to do with it. The advantage of sweep in the transsonic region being that the chord of the wing is phisically increased by sweeping the wing back (or foreward) to the extent that the COS of the sweep angle muliplied by the original thickness/chord will give the "real" thickness/chord. However, a thin, straight wing will work just as well for this purpose. (hence the Bell X-1, Douglass Skystreak, F-94C, CF-100, etc)
Now at supersonic speeds, swept back wings (or a Delta planform) have other advantages, but that's a different issue.
Additionally, the portion of the Me 262's wing that was swept back (for trim purposes) was only that outboard of the engines, the inboard portion being unswept (although the LE of the inboard section was extended to match the sweep angle of the LE of the rest of the wing). So, while the 18.5° wing sweep of the outer wing would result in the airfoil thicness being resuced to ~94.8% of the original thickness, the inboard section will be unaffected. (additionally the root had max thickness at 35% chord while this increased to 40% for the entire outboard section)
Given that the Skystreak, F-94C, and CF-100 all had wings of 10% thickness (the former two being laminar flow types, and the latter being a simple, unmodified NACA 0010) it would seem that the Me 262's wing was fairly close to being satisfactory in transsonic flight. (being 10% thicker at the root)
Bill, I agree that the control problems on the Me 262 should start to manifest at a TAS of ~914 km/h (568 mph/494 kt) at ~36,000 ft. I'm not entirely sure Soren was implying that the airspeed indicated on the Me 262 was close to the TAS, I think it may be another case of misenterpretation.
Soren, could you clarify what you meant by the 1,100 km/h figure? (did you simply mean that this was the indicated speed when the control problems occured?)
Now at supersonic speeds, swept back wings (or a Delta planform) have other advantages, but that's a different issue.
Additionally, the portion of the Me 262's wing that was swept back (for trim purposes) was only that outboard of the engines, the inboard portion being unswept (although the LE of the inboard section was extended to match the sweep angle of the LE of the rest of the wing). So, while the 18.5° wing sweep of the outer wing would result in the airfoil thicness being resuced to ~94.8% of the original thickness, the inboard section will be unaffected. (additionally the root had max thickness at 35% chord while this increased to 40% for the entire outboard section)
Given that the Skystreak, F-94C, and CF-100 all had wings of 10% thickness (the former two being laminar flow types, and the latter being a simple, unmodified NACA 0010) it would seem that the Me 262's wing was fairly close to being satisfactory in transsonic flight. (being 10% thicker at the root)
Bill, I agree that the control problems on the Me 262 should start to manifest at a TAS of ~914 km/h (568 mph/494 kt) at ~36,000 ft. I'm not entirely sure Soren was implying that the airspeed indicated on the Me 262 was close to the TAS, I think it may be another case of misenterpretation.
Soren, could you clarify what you meant by the 1,100 km/h figure? (did you simply mean that this was the indicated speed when the control problems occured?)
kool kitty89
Senior Master Sergeant
Also, the study Soren is referring to, I believe is the same one Delcyros introduced on the first page of this thread.
also, Hans Guido Mutke - Wikipedia, the free encyclopedia
And, I'm not entirely sure of the accuracy of everything on the Me 262 reproduction website. While I too noticed that rather stark announcement that the 540 mph speed would not be exceeded, even thought the Me 262 should be well capable of 620+ mph below 10,000 ft given its Mach limit, and that the official "never excced speed" was also well above this figure.
It should be noted that in one of their featured videos that it is stated that "its top speed is 560 knots, just like the originals."
Also they claim that
Firstly, there are at least 11 surviving Me 262's (including 2 Czech S.92's) and Me 262 A-1a/U3 W.Nr.500453 (fromerly owned by Planes of Fame, and the same ship Howard Hughes tried to use for racing) is now part of Paul Allen's "Flying Heretage Collection" and is currently being restored to flying condition. (which, incedentally, is also located in Washinton, in Arlington, pretty close to Everett -both being in west Sonhomish county-)
also, Hans Guido Mutke - Wikipedia, the free encyclopedia
And, I'm not entirely sure of the accuracy of everything on the Me 262 reproduction website. While I too noticed that rather stark announcement that the 540 mph speed would not be exceeded, even thought the Me 262 should be well capable of 620+ mph below 10,000 ft given its Mach limit, and that the official "never excced speed" was also well above this figure.
It should be noted that in one of their featured videos that it is stated that "its top speed is 560 knots, just like the originals."
Also they claim that
Firstly, there are at least 11 surviving Me 262's (including 2 Czech S.92's) and Me 262 A-1a/U3 W.Nr.500453 (fromerly owned by Planes of Fame, and the same ship Howard Hughes tried to use for racing) is now part of Paul Allen's "Flying Heretage Collection" and is currently being restored to flying condition. (which, incedentally, is also located in Washinton, in Arlington, pretty close to Everett -both being in west Sonhomish county-)
kool kitty89
Senior Master Sergeant
I caught this a while back, but forgot to ask. What do you mean by "boosted 262 elevator." Did it feature boosted controls?
drgondog
Major
494kts at STP at 35000 is ~ .86M which is the alleged 'start of disintegration' for a 262 - every reference I have seen for Messerschmidt is Do not Eceed .84 Mach.
FYI for Kts the Speed of sound is 29.04*sqrt(T) where T = Temp in Rankin
At 36K, T=390.5
At 25K =429.6
At 15K =465.2
At SL = 518.7 for Standard Temp and Pressure (59 Degree F, 2116 lb/ft^^2 at SL)
Bill,
The reason the reproduction Me-262's aren't pushed past 500 mph should be quite clear to you. It isn't because of doubts regarding wether the a/c will disintigrate or not, it is for other obvious safety reasons only. They don't push Mustangs to 430 mph today either, or F-86's to 600 mph, again for safety reasons.
From the site:
The fact remains that the airframe was never designed to handle the stress loads encountered at speeds in the 600 mile per hour range. To push the aircraft into this environment simply because additional power "happens to be available" is a highly dangerous and ill-advised move.
In the interest of safety, the Me 262 Project will be placing a placarded airspeed limitation upon the jets in the vicinity of 500 MPH. The official position of the project is that there is simply no need -- or benefit -- in flying these aircraft any faster.
Or would you advice them to put millions of dollars on stake just to try and break the sound barrier ?
Anyway I believe modern research done by professional aerodynamicists more than any hunch someone might have.
The reason the reproduction Me-262's aren't pushed past 500 mph should be quite clear to you. It isn't because of doubts regarding wether the a/c will disintigrate or not, it is for other obvious safety reasons only. They don't push Mustangs to 430 mph today either, or F-86's to 600 mph, again for safety reasons.
From the site:
The fact remains that the airframe was never designed to handle the stress loads encountered at speeds in the 600 mile per hour range. To push the aircraft into this environment simply because additional power "happens to be available" is a highly dangerous and ill-advised move.
In the interest of safety, the Me 262 Project will be placing a placarded airspeed limitation upon the jets in the vicinity of 500 MPH. The official position of the project is that there is simply no need -- or benefit -- in flying these aircraft any faster.
Or would you advice them to put millions of dollars on stake just to try and break the sound barrier ?
Anyway I believe modern research done by professional aerodynamicists more than any hunch someone might have.
Users who are viewing this thread
Similar threads
