Henk
Master Sergeant
Thanks mate.
Henk
Henk
Best Fighter III
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syscom3
Pacific Historian
Were those supersonic speeds verfied by ground based measurements? I remember someone here mentioning (some time ago) that in the 40's, measuring sonic and supersonic speeds by in flight measurement systems could be wildly inaccurate.
FLYBOYJ
"THE GREAT GAZOO"
What supersonic speeds?
I've heard, and firmly believe, that the Me-262 did achieve supersonic speeds during World War II. I've read a couple of pilot reports that mention power-diving at an altitude where the speed of sound is slower than ground level, and actually losing track of the speed as they started to pull out. This accompanied with the reports of effects on control, and vibrations make me think they would have broken it.
Also, a few reports have come about of Me-262s falling to pieces in a dive. And, most controversial, loud bangs being heard by pilots around when there was no firing. The sonic boom...!
Also, a few reports have come about of Me-262s falling to pieces in a dive. And, most controversial, loud bangs being heard by pilots around when there was no firing. The sonic boom...!
syscom3
Pacific Historian
The airspeed instruments of that era (middle 40's) were not accurate at transsonic, sonic and supersonic speeds.
Instrument readings from inside the aircraft should not be believed.
Instrument readings from inside the aircraft should not be believed.
evangilder
"Shooter"
From one of my articles on the P-47:
I too kind of question claims like those. I am not sure that the Me-262 airframe could take that speed.
I too kind of question claims like those. I am not sure that the Me-262 airframe could take that speed.
FLYBOYJ
"THE GREAT GAZOO"
Yep!
I have already stated that the indicated airspeed wasn't where the belief came from. On more than one occasion aircraft were reported to fall apart in a dive. On more than one occasion "loud bangs" were reported while in combat, and it didn't sound like gunfire.
I don't know, but what I read was pretty convincing. And I don't take it as the solid truth, but it's possible.
I don't know, but what I read was pretty convincing. And I don't take it as the solid truth, but it's possible.
evangilder
"Shooter"
If it was breaking up, I would think that it is possible then. I seem to remember reading somewhere the Me-262 could not break the sound barrier without breaking apart.
Jabberwocky
Staff Sergeant
I have read something similar.
Because of the uneven distribution of airflow over the airframe of the Me-262, supersonic flight is THOUGHT to have been impossible, purely from an engineering and darg perspective.
At very high speeds certain sections of the airflow over the fuselage and wings would exceed the speed of sound, while other sections remained subsonic. The resulting flow turbulence from the supersonic shockwave of the airflow over the wings and other empennage could cause massive buffeting and asymmetric airflows, enought to dramatically increase the drag profile.
Supposedly, localised airflow exceeded the speed of sound around the wingroots and inner wing, engine nacells and tailplane. It may of been possible that the German jet went trans-sonic, but the resulting spikes in turblence and drag kept it firmly below the sound barrier.
Messerschmitt research suggested that the Me-262 could get above Mach .85 before local airflows became supersonic and the plane became uncontrollable. Mach .85 seems to be the highest value they were willing to test at.
Because of the uneven distribution of airflow over the airframe of the Me-262, supersonic flight is THOUGHT to have been impossible, purely from an engineering and darg perspective.
At very high speeds certain sections of the airflow over the fuselage and wings would exceed the speed of sound, while other sections remained subsonic. The resulting flow turbulence from the supersonic shockwave of the airflow over the wings and other empennage could cause massive buffeting and asymmetric airflows, enought to dramatically increase the drag profile.
Supposedly, localised airflow exceeded the speed of sound around the wingroots and inner wing, engine nacells and tailplane. It may of been possible that the German jet went trans-sonic, but the resulting spikes in turblence and drag kept it firmly below the sound barrier.
Messerschmitt research suggested that the Me-262 could get above Mach .85 before local airflows became supersonic and the plane became uncontrollable. Mach .85 seems to be the highest value they were willing to test at.
delcyros
Tech Sergeant
Thanks a lot JonJ!
delcyros
Tech Sergeant
Mach 0.85 (english source) or Mach 0.86 (Messerschmidt calculation) is the critical Mach speed at which the planes controll loose functionality. At higher speeds the plane gets strongly nose heavy (Mach trim) and will enter an otherwise terminal dive.
However, THIS WILL NOT PREVENT THE PLANE FROM FURTHER ACCELERATION. In a 60 degrees full power dive the Me-262 delivers the eaquivalent of 5.790 Kp thrust (~12.750 lbs). This power will overcome the high drag produced between Mach 0.85 and 1.18. Recent calculations proved this. As Syscom pointed out, there were no reliable transsonic instruments except for the Machmeter installed in the Me-163B. Still the instruments may show a Mach jump (described by Mutke as well as by those XF-86 transsonic dives). At speeds beyond Mach 1.03 the airflow over the wing will again allow the controll surfaces to take effect.
If we thrust Mutke, he might be well beyond Mach 1.0:
He was at training flight in over 35.000 ft when he entered a full power dive to assist another attacked Me-262 5.000 m below him. At this altitude the speed of sound is around 1080 Km/h (670 mp/h) and increases gradually as he closes to the ground. He then looses controll and entered an even steeper angle of dive, still with full power. Despite heavy buffeting he then noticed a speed indicator jump (around 7.000m, "IAS" beyond 1.100 Km/h on the stopping point)and regained controlls. The Jumo´s, however, got quickly a flameout. At this altitude he was between 3.000 m and 5.000 m and could recover the (heavily damaged) plane for a gliding landing. It is technically more a question of aeroelastics than a question of drag. If he only was briefly in the dangerous speed zone ( between Mach 0.85 and 1.03), the airframe may sustain the stress by heavy buffeting, if he stayed longer the airframe would desintegrate due to excessive negative loadings (this also happened at least three times recorded). So the question is was the dive steep enough to slip through the dead zone or not? Could the airframe sustain all the stress or not and in which timeframe?
Mutke later was hardly attacked by Bär for damaging the Me-262 that much. The plane had to be written off.
However, THIS WILL NOT PREVENT THE PLANE FROM FURTHER ACCELERATION. In a 60 degrees full power dive the Me-262 delivers the eaquivalent of 5.790 Kp thrust (~12.750 lbs). This power will overcome the high drag produced between Mach 0.85 and 1.18. Recent calculations proved this. As Syscom pointed out, there were no reliable transsonic instruments except for the Machmeter installed in the Me-163B. Still the instruments may show a Mach jump (described by Mutke as well as by those XF-86 transsonic dives). At speeds beyond Mach 1.03 the airflow over the wing will again allow the controll surfaces to take effect.
If we thrust Mutke, he might be well beyond Mach 1.0:
He was at training flight in over 35.000 ft when he entered a full power dive to assist another attacked Me-262 5.000 m below him. At this altitude the speed of sound is around 1080 Km/h (670 mp/h) and increases gradually as he closes to the ground. He then looses controll and entered an even steeper angle of dive, still with full power. Despite heavy buffeting he then noticed a speed indicator jump (around 7.000m, "IAS" beyond 1.100 Km/h on the stopping point)and regained controlls. The Jumo´s, however, got quickly a flameout. At this altitude he was between 3.000 m and 5.000 m and could recover the (heavily damaged) plane for a gliding landing. It is technically more a question of aeroelastics than a question of drag. If he only was briefly in the dangerous speed zone ( between Mach 0.85 and 1.03), the airframe may sustain the stress by heavy buffeting, if he stayed longer the airframe would desintegrate due to excessive negative loadings (this also happened at least three times recorded). So the question is was the dive steep enough to slip through the dead zone or not? Could the airframe sustain all the stress or not and in which timeframe?
Mutke later was hardly attacked by Bär for damaging the Me-262 that much. The plane had to be written off.
FLYBOYJ
"THE GREAT GAZOO"
Good info guys - I know a similar situation holds true for the Mig-15 - I believe it had a higher critical Mach number but unlike the Me-262 it would not accelerate much past that and would actually destroy itself if any attempt was made to exceed this and go beyond Mach 1.
I would not discount any story about the Me-262 going Mach 1....
I would not discount any story about the Me-262 going Mach 1....
delcyros
Tech Sergeant
It is indeed a comparable situation. The higher crit Mach figure of the Mig-15 is reasoned by it´s higher wing sweep degree. The airfoil, however, is significant thicker than that of the Me-262 and will produce a considerable higher degree of buffeting and drag (the wing sweep doesn´t offset the high drag, it just shift the high drag zone to higher speeds) at transsonic speeds. This is obvious if we compare the contemporary wing designs of La-15 and Mig-15. The former was able to reach Mach 1 because of a much thinner airfoil and little more sweep. Anyway, I believe that if any Me-262 got supersonic, this strongly is subject to accident actions rather than design features.
JonJGoldberg
Airman 1st Class
...Sorry, been very busy at work these days.
delcyros Posted: Mon Feb 20, 2006 7:07 am "...Anyway, I believe that if any Me-262 got supersonic, this strongly is subject to accident actions rather than design features."
I could not agree more, but feel the plane either would be normally un-flyable if not destroyed during or after the event, as you imply. I'm going to be slammed for this... But my sim confirms this, as speeds beyond 660 mph cause airframe damage, at any density altitude. (I edit or create damage profiles using data acquired from manuals or from the spread sheet you may download here {http://www.ww2aircraft.net/forum/about962-0-asc-520.html}, find more info about the methods and math by going back a few pages.) Believe it or not, I still have greater faith in the calculation, than the report I posted.
delcyros Posted: Mon Feb 20, 2006 7:07 am "...Anyway, I believe that if any Me-262 got supersonic, this strongly is subject to accident actions rather than design features."
I could not agree more, but feel the plane either would be normally un-flyable if not destroyed during or after the event, as you imply. I'm going to be slammed for this... But my sim confirms this, as speeds beyond 660 mph cause airframe damage, at any density altitude. (I edit or create damage profiles using data acquired from manuals or from the spread sheet you may download here {http://www.ww2aircraft.net/forum/about962-0-asc-520.html}, find more info about the methods and math by going back a few pages.) Believe it or not, I still have greater faith in the calculation, than the report I posted.
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delcyros
Tech Sergeant
I will second your thoughts about the Me-262.
I have a question to these charts, Jonny.
Are they based on mathematicla-physical, empirical, or litterally evidence? I am interested in these complex threads but had much problems with the mathematical part and probelms with literatures (take the flight manuals for example, according to Luftwaffe acceptance limits the printed max speed figures for a dive have to be exceeded by at least 15% guaranteed I am told later) as well.
Keep up the good work!
I have a question to these charts, Jonny.
Are they based on mathematicla-physical, empirical, or litterally evidence? I am interested in these complex threads but had much problems with the mathematical part and probelms with literatures (take the flight manuals for example, according to Luftwaffe acceptance limits the printed max speed figures for a dive have to be exceeded by at least 15% guaranteed I am told later) as well.
Keep up the good work!
JonJGoldberg
Airman 1st Class
Delcyros thanks. I've posted lots of stuff related to the information on my tables. Data sources are given in the tables, and as for the rest, they were calculations. I can refer you here ( http://www.ww2aircraft.net/forum/about1116-0-asc-40.html ). Start with my post Nov 19, 2005 10:31 pm; I think you will enjoy the reading from there, as it provides the most complete answer I could give you with regard to its 'accuracy'.
You bring up a very interesting point, which I do not think I've answered as of yet… You state "…according to Luftwaffe acceptance limits the printed max speed figures for a dive have to be exceeded by at least 15% guaranteed I am told later) as well."
I have never seen; not to say that it does not exist, nor am I saying that it is not true, or that it was not done; any 'official' document claiming published limits can be exceeded by X-amount; but Wmaxt has, for sure, as he has referenced published P-38 capabilities above those instructed within the 'pilot's manual', he has been a man of his word... However, please note that published limits are written to protect the pilot, in theory, from himself, as well as to establish an accepted performance 'minimum standard'. This minimum standard requires 'margins', typicaly from about 10 to 15%, for natural occurrences such as altitude, speed, wind, rain, cold, hot, lighter than normal or heavier than normal operation…
I realize that the published 'max' settings in combat are the settings where the fun starts. They were probably regularly exceeded. But here we enter into other regions, and expose ourselves to arguments I feel I must avoid at all cost, when producing a table such as the one I produced …Pilot skill unverifiable numbers.
When by how much a 'stat' could be exceeded is a matter an operator makes at the moment; it is the reason there were upsets by pilots who flew in what were as claimed before race day, as 'inferior aircraft' to the 'top contenders' in the Schneider Trophy races.
You say the safe to exceed limit is 15%, and go on to offer a blank guarantee. OK; say you… Not to pick a fight, but in telling me this you seem to be 'verifying' it to yourself, nothing wrong with that, per say... Especially because in this instance I believe you to be correct. But, once again, as for the 'table' this to me would be a no-no. So the numbers that appear in the table are meant to represent 'allowable' published maximums. You may infer from here what would happen if you were to exceed them, but if I were to use those numbers how would we get back to the 'published' maximums. No better that you apply your 'variance' as you see fit.
I myself re-interpret the numbers you see in the tables to produce 'air' 'damage profiles' for my combat Sims.
You bring up a very interesting point, which I do not think I've answered as of yet… You state "…according to Luftwaffe acceptance limits the printed max speed figures for a dive have to be exceeded by at least 15% guaranteed I am told later) as well."
I have never seen; not to say that it does not exist, nor am I saying that it is not true, or that it was not done; any 'official' document claiming published limits can be exceeded by X-amount; but Wmaxt has, for sure, as he has referenced published P-38 capabilities above those instructed within the 'pilot's manual', he has been a man of his word... However, please note that published limits are written to protect the pilot, in theory, from himself, as well as to establish an accepted performance 'minimum standard'. This minimum standard requires 'margins', typicaly from about 10 to 15%, for natural occurrences such as altitude, speed, wind, rain, cold, hot, lighter than normal or heavier than normal operation…
I realize that the published 'max' settings in combat are the settings where the fun starts. They were probably regularly exceeded. But here we enter into other regions, and expose ourselves to arguments I feel I must avoid at all cost, when producing a table such as the one I produced …Pilot skill unverifiable numbers.
When by how much a 'stat' could be exceeded is a matter an operator makes at the moment; it is the reason there were upsets by pilots who flew in what were as claimed before race day, as 'inferior aircraft' to the 'top contenders' in the Schneider Trophy races.
You say the safe to exceed limit is 15%, and go on to offer a blank guarantee. OK; say you… Not to pick a fight, but in telling me this you seem to be 'verifying' it to yourself, nothing wrong with that, per say... Especially because in this instance I believe you to be correct. But, once again, as for the 'table' this to me would be a no-no. So the numbers that appear in the table are meant to represent 'allowable' published maximums. You may infer from here what would happen if you were to exceed them, but if I were to use those numbers how would we get back to the 'published' maximums. No better that you apply your 'variance' as you see fit.
I myself re-interpret the numbers you see in the tables to produce 'air' 'damage profiles' for my combat Sims.
Attachments
delcyros
Tech Sergeant
Nice reading, JonJ.
I truly understand the problems You have dealing with uncertainities by pushing the flight envelope at/beyond limits.
My favourite interests are in late war, early jet planes, so I have only few flightmanuals (all copys) from:
Ta-152 H0 (translation work for Lunatic, posted in this forum)
Ar-234B2 (copy by Luftarchiv Hafner, original from dt. Museum)
Me-262 A1 (as above)
He-162 A1 (copy from original storaged in Leipzig archive)
He-162 A2 (copy from Luftarchiv Hafner, original from dt. Museum)
In order to give a sample I will take the He-162 example.
According to the the He-162 A2 flight manual (Bedienvorschrift Baubeschreibung Ausg. 1944) the max speed at sea level is 700 Km/h indicated (thus 750 Km/h TAS, since the instrument is constantly showing 10% less than true) =page 5, line 6 of the flight manual (ausg. 1944, printed march 1945)
while in the contemporary Baubeschreibung (Ausg. 1944, printed in march 1945) page 1 line 17 the figure is given with 800 Km/h at sea level and 1000 Km/h at ~3.200 ft (1.000 m). Other documents (published in Luftfahrt International 26) related to He-162 state that 1000 Km/h was the max speed to recover from a dive at 17 Kp stick forces and 3.5 G (this alone implies a larger technical envelope for the plane as well since recovering from a 1000 Km/h dive at 1000 m altitude is not possible, therefore the altitude must be [a lot] higher). In every respect (regardless of altitude) 1000 Km/h are far more than the 700, resp. 750 Km/h figure given in the flight manual for the pilot. The same document accuses worse executed production at different plane constructeurs (not EHAG), which don´t match for these Luftwaffe acceptance limits.
I have similar phenomens in the flight manuals and construction manuals for Ta-152 H0, Ar-234 B2 and of course, the Me-262 A1 as well.
Another highly intersting book I own is "Metallflugzeugbau" in an edition from 1943 covering materials, working technicques, maths and basic airplane tooling. This is a wartime edition and provides excellent background informations regarding the working environment in mid war times (written for labourers). The definition part alone is interesting:
"N(sicher): Lastvielfaches beim Abfangen" (N(secure):G-forces at dive recovering)
"N(bruch): Minimales Lastvielfaches deren Überschreiten einen Bruch zur Folge haben kann, je nach Festigkeitsgruppe:
H 1= N(sicher)+1/-0.5 (not for Planes)
H 2= N(sicher)+1.5/-1 (not for warplanes)
H 3= N(sicher)+2/-1
H 4= N(sicher)+3/-1.5
H 5= N(sicher)+4/-2
H 6= N(sicher)+5/-3
N(breaking): minimal G-forces, whichs exceeding may cause an airfame failure, according to goup of construction stiffness:
In case of the He-162 according to the flight maual: 6.5g at Festigkeitsgruppe H5 = +10.5g (=max safe g-forces at 2.500 Kg true weight). Early He-162 A2 were limited to 4g at H5 (therefore 8g max).
Anyway a really interesting matter. I may post scans if needed as soon as I get the digicam back.
I truly understand the problems You have dealing with uncertainities by pushing the flight envelope at/beyond limits.
My favourite interests are in late war, early jet planes, so I have only few flightmanuals (all copys) from:
Ta-152 H0 (translation work for Lunatic, posted in this forum)
Ar-234B2 (copy by Luftarchiv Hafner, original from dt. Museum)
Me-262 A1 (as above)
He-162 A1 (copy from original storaged in Leipzig archive)
He-162 A2 (copy from Luftarchiv Hafner, original from dt. Museum)
In order to give a sample I will take the He-162 example.
According to the the He-162 A2 flight manual (Bedienvorschrift Baubeschreibung Ausg. 1944) the max speed at sea level is 700 Km/h indicated (thus 750 Km/h TAS, since the instrument is constantly showing 10% less than true) =page 5, line 6 of the flight manual (ausg. 1944, printed march 1945)
while in the contemporary Baubeschreibung (Ausg. 1944, printed in march 1945) page 1 line 17 the figure is given with 800 Km/h at sea level and 1000 Km/h at ~3.200 ft (1.000 m). Other documents (published in Luftfahrt International 26) related to He-162 state that 1000 Km/h was the max speed to recover from a dive at 17 Kp stick forces and 3.5 G (this alone implies a larger technical envelope for the plane as well since recovering from a 1000 Km/h dive at 1000 m altitude is not possible, therefore the altitude must be [a lot] higher). In every respect (regardless of altitude) 1000 Km/h are far more than the 700, resp. 750 Km/h figure given in the flight manual for the pilot. The same document accuses worse executed production at different plane constructeurs (not EHAG), which don´t match for these Luftwaffe acceptance limits.
I have similar phenomens in the flight manuals and construction manuals for Ta-152 H0, Ar-234 B2 and of course, the Me-262 A1 as well.
Another highly intersting book I own is "Metallflugzeugbau" in an edition from 1943 covering materials, working technicques, maths and basic airplane tooling. This is a wartime edition and provides excellent background informations regarding the working environment in mid war times (written for labourers). The definition part alone is interesting:
"N(sicher): Lastvielfaches beim Abfangen" (N(secure):G-forces at dive recovering)
"N(bruch): Minimales Lastvielfaches deren Überschreiten einen Bruch zur Folge haben kann, je nach Festigkeitsgruppe:
H 1= N(sicher)+1/-0.5 (not for Planes)
H 2= N(sicher)+1.5/-1 (not for warplanes)
H 3= N(sicher)+2/-1
H 4= N(sicher)+3/-1.5
H 5= N(sicher)+4/-2
H 6= N(sicher)+5/-3
N(breaking): minimal G-forces, whichs exceeding may cause an airfame failure, according to goup of construction stiffness:
In case of the He-162 according to the flight maual: 6.5g at Festigkeitsgruppe H5 = +10.5g (=max safe g-forces at 2.500 Kg true weight). Early He-162 A2 were limited to 4g at H5 (therefore 8g max).
Anyway a really interesting matter. I may post scans if needed as soon as I get the digicam back.
Now that I have some time finally I will respond to some of this.
I am sure that Bf-109s and Fw-190s shot down more than 4850 acft a piece.
And then I read down and find this stuff from this Jon guy....
I will keep my responses short and sweet.
No actually I do not have a closed mind, it is actually very open to people opinions, you just cant handle the fact that people dont agree with you. Sounds to me like a personal problem. And by the way if go back and read your posts, they sound more like personal attacks in some of them.
Besides you just said it right there that you do not respect my opinions. Well here you go, in order to earn respect you have to give. I no longer have any respect for you. I did until now, when we were just discussing, but until you earn my respect back again, as far as I am concerned you are just a guest on this forum.
One more insult to myself or another admin on this forum and you will not be very happy.
JonJGoldberg said:
I am sure that Bf-109s and Fw-190s shot down more than 4850 acft a piece.
And then I read down and find this stuff from this Jon guy....
I will keep my responses short and sweet.
JonJGoldberg said:
No actually I do not have a closed mind, it is actually very open to people opinions, you just cant handle the fact that people dont agree with you. Sounds to me like a personal problem. And by the way if go back and read your posts, they sound more like personal attacks in some of them.
Besides you just said it right there that you do not respect my opinions. Well here you go, in order to earn respect you have to give. I no longer have any respect for you. I did until now, when we were just discussing, but until you earn my respect back again, as far as I am concerned you are just a guest on this forum.
JonJGoldberg said:
One more insult to myself or another admin on this forum and you will not be very happy.
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