BF 109 Dive Rate

[Burmese Bandit]

I do not have the exact figures, but here is the rough and ready:

Me 109 G versus

Spit 9 - 109 is much faster at the beginning of dive and still slighty better after some time
Spit 14 - 109 is slightly faster at beginning but as both aircraft reach 450 mph Spit 14 begins to overtake
Tempest - 109 is again slightly faster at beginning but Tempest begins to overtake at about 440
Mustang D - 109 has only a tiny advantage at beginning,Mustang overtakes at about 470, but rate of overtake is slightly slower than Spit 14 or Tempest
The Jug - 109 is faster at beginning bit from 450 onwards the 47 overtakes the 109 like a Porsche in your rearview mirror!

 

[davebender]

In other words the Me-109 has a faster dive rate more or less to the max permissible speed (except vs P47). Which is what really counts as the Me-109 pilot needs to be contemplating a different maneuver once speed passes 450mph.

 

[drgondog]

In other words the Me-109 has a faster dive rate more or less to the max permissible speed (except vs P47). Which is what really counts as the Me-109 pilot needs to be contemplating a different maneuver once speed passes 450mph.

Dave - in some cases only the initial 100 yards or so, after that all the others caught up to it.. My father chased and caught three 109s in a dive in a 51d - that did not get away - the other 4 were in turning fights - that did not get away - and lost one in one 360 degree turn that another 51D got bored watching and shot him down.

 

[Glider]

In other words the Me-109 has a faster dive rate more or less to the max permissible speed (except vs P47). Which is what really counts as the Me-109 pilot needs to be contemplating a different maneuver once speed passes 450mph.

The other problem the 109 would have had was that he was out of options. The 109 controls became very heavy at speed and at close to max were very difficult to operate. So if the 109 waits until he is going around 450 he is out of options as most of the opposition handled better at high speed.
So unless he found a cloud quickly he was in serious trouble

 

[davebender]

The Me-109 series could out climb everyone else. Assuming you still have elevator control at 450 mph.

 

[drgondog]

The Me-109 series could out climb everyone else. Assuming you still have elevator control at 450 mph.

I am not sure that is true for a zoom climb - but equally not prepared to debate it.

 

[Glider]

The Me-109 series could out climb everyone else. Assuming you still have elevator control at 450 mph.

I also doubt that statment, do you have anything to support it?

 

[Butters]

By happy coincidence, I'm re-reading Bob Johnson's and Caiden's, 'Thunderbolt' right now. In his combat accounts he makes repeated references to '109s and '190s attempting to escape his Jug by diving away.

"They never learn...", he says. Often, he had to cut the throttle to avoid over-running them. He also mentions that the paddle-prop equipped '47 could climb with anything he flew against, both Allied and German (at least in the short-term). And in the zoom, even the early Jugs were more than a match for its much lighter opponents.

JL

 

[Kurfürst]

The Me 109 G was red lined at 466mph whereas the Spit IX was redlined at around 455mph so the difference wasn't great but the 109 in a dive accelerated faster so had a tactical advantage greater than the actual numbers indicated. Its a short term gain as Terra Ferma will be reached sooner or later.

However the P51 and P47 were redlined at speeds in excess of 500 mph so the 109 was at a significant disadvantage when trying to dive away.

I am trying to dig out the exact numbers but this is a rough guide

I don't think so - from everything I have seen the dive 'limits' for the aircraft were pretty theoretical, and were more of a rough guess and a telling sign of the manufacturer's conservatism than anything else.. AFAIK, no serious terminal dive tests were even made until 1943 with most of the major types, and that was only done after report of odd behavior as combat pilots started to reach into high Mach numbers... the 109 for example - ditto the 190 - had it set at 750 kph IAS (all models from E/F/G and perhaps the earlier ones too, even though you would think there would be some difference? the 109K was set at 850kph/527mph, although again I doubt this would be largely due to some kind of improvement, rather than increased confidence that there would be no trouble.) To put it simple, the Diving Limits set were largely guesswork.

Also, regardless of the dive speeds, from every single extreme dive test report I have seen, none of the 'big names' were truely controllable above around ca Mach 0.75. Compressibility effects were begun to be felt. There was no exception. Above that speed, if even reached in combat, the aircraft were diving uncontrollably until they reached lower altitude, and one of the pilots decided it was enough, and pulled up - or pancaked.

Personally I think, and here comes the human factor which on a discussion board may be neglected, the biggest limitating factor on dive speeds was not on a place card riveted to the cocpit wall, but between the pilot's legs... its easy to read reports, but you are reading a pilots account, you may get the full horror of a vertical dive in a fighter plane at r at 700-800 kph. Most were simply convinced that they were going to die - the airframe was cracking, and they knew when something goes wrong (and when it does, they knew that they will just die, there was no chance or time to get out), blood was pouring out of their ears as your eardrums can't take the rapid descent etc. It took a human being to the extreme limits of his phychological and physical endurance - most of the time, the plane could take a lot more..

 

[Glider]

The numbers quoted are from the Pilots notes iro the P47 and P51 and official German documentation advising pilots of the airspeed limitations for the Me109. The Spitfire number I am trying to check but am confident that its about right.

Obviously a red line speed is not definate ie if the red line speed is 500mph it doesn't mean that the aircraft will fall apart at 505 mph but equally obviously, the more you push your luck the greater the risk.

I have more confidence in the designers of the time than you do but at least its a common point for discussion for the thread.

 

[GrauGeist]

There is an account in James Goodson's book "Tummult in the Clouds" where Goodson bent the wings on his his P-47D in a dive when he was trying to shake some Fw190s off Don Blakeslee's tail. (Don Blakeslee's P-47 was holed and covered in oil)

Goodson not only pulled out of the terrific dive and survived, but was able to bluff the Fw190s away from Blakeslee, both of them making it back across the channel safely. I understand that Goodson's jug was scrapped after that, though.

And good post info, Kurfürst!

 

[Mangrove]

I agree with Kürfurst.

Messerschmitt 109 - myths, facts and the view from the cockpit

Diving - structural rigidity of 109 in dives

The Me 109 was dived to Mach 0.79 in instrumented tests. Slightly modified, it was even dived to Mach 0.80, and the problems experimented there weren't due to compressility, but due to aileron overbalancing. Compare this to Supermarine Spitfire, which achieved dive speeds well above those of any other WW2 fighter, getting to Mach 0.89 on one occasion. P-51 and Fw 190 achieved about Mach 0.80. The P-47 had the lowest permissible Mach number of these aircraft. Test pilot Eric Brown observed it became uncontrollable at Mach 0.73, and "analysis showed that a dive to M=0.74 would almost certainly be a 'graveyard dive'."
- Source: Radinger/Otto/Schick: "Messerschmitt Me 109", volumes 1 and 2, Eric Brown: "Testing for Combat".
- (Comment: it seems Eric Brown's analysis is flawed, though, and test pilot Herb Fisher performed 150+ such dives: an example of a 0.79 dive. Several of the dives achieved Mach 0.83. Sources: Herb Fisher, Herb Fisher Jr., and Curtiss-Wright.


Me 109 G:
"Me 109 had good and accurate weapons, but those were the only good points of it. To me, it's unacceptable that somebody had built a fighter plane that couldn't be dived without limits. Me109 had a dive limit of 880km/h - you weren't to exceed it or the plane would break up. Just this happened to Sgt Mäittälä. I (and Pokela) was forced to exceed this limit twice, I can't describe how it felt just to sit in the cockpit waiting, if the plane would break up. I have never gotten rid of that feeling, of being trapped."
-Heimo Lampi, Finnish fighter ace. 13 1/2 victories. Source: Hannu Valtonen, "Me 109 ja Saksan sotatalous" (Messerschmitt Bf 109 and the German war economy), ISBN 951-95688-7-5.

 

[davebender]

To me, it's unacceptable that somebody had built a fighter plane that couldn't be dived without limits.

I can understand this guys anger. But there is not much you can do if the aerodynamic principles have yet to be discovered during the mid 1930s.

Out of curiosity, do modern fighter aircraft like the F-15 have a dive speed limit?

 

[DAVIDICUS]

At 1,500mph, an aircraft is traveling 2,200 feet per second - 25 miles per minute.

A bullet from an AK-47, at the muzzle, is traveling just a bit faster.

 

[drgondog]

I can understand this guys anger. But there is not much you can do if the aerodynamic principles have yet to be discovered during the mid 1930s.

Out of curiosity, do modern fighter aircraft like the F-15 have a dive speed limit?

Dave - offhand I don't know what it is or the mode..

Short answer is that there is surely a 'q limit' that probably is at lower altitudes (below 25K) related to stresses imposed by aerodynamic pressure loads and distribution. I also imagine the Ultimaet loadlimit wouldn't be in a terminal dive but in combination with G forces and asymmetrical loads in a turn or pullout - (strange, just like a Me 109! or P-51)

 

[Glider]

I can understand this guys anger. But there is not much you can do if the aerodynamic principles have yet to be discovered during the mid 1930s.

Out of curiosity, do modern fighter aircraft like the F-15 have a dive speed limit?

All aircraft, from the oldest to the newest, the fastest F15 jets to the Gliders that I flew have limitations. In Particular all have a VNE (Velocity Not to Exceed or Velocity Never Exceed) and Stress limitations.

As mentioned in an earler posting I noted that these are not definate figures, but the more you go over the line the greater the chance of failure.
I have seen an F4 that pulled 12G, it made it home but never flew again.

 

[Buccaneer]

The following is an extract from a original Personal Combat Report, in my possession, dated 12 July 1944, from S/Ldr Gilmour, 19 Squadron, flying a Mustang:
'He half rolled down and I followed him. He was going down almost vertically and I could not get my sights on him. We went through cloud in this attitude. When he started pulling out (about 3,000ft) I tried to get behind him again. At this moment his port wing snapped off and the a/c flicked violently straight into the ground. I looked at my ASI and it was showing over 600 m.p.h. I blacked out pulling out. When I came to again I climbed back to 12,000ft.'
That's what happens when a Me 109 exceeds its limits!

 

[davebender]

That can happen when any aircraft exceeds its limits. The P-51 pilot was lucky. The Me-109 pilot was not.

 

[FLYBOYJ]

That can happen when any aircraft exceeds its limits. The P-51 pilot was lucky. The Me-109 pilot was not.

Lucky? No - the P-51's wing had a higher critical mach number and was able to endure compressibility better than many other WW2 aircraft.

 

[Dark Matter]

True.

The P-51 had small wings whitch gave them areadinamics.

The P-47 was teh best diver though.