P-51D maneuvrability - what it was in reality ...

[Erich]

gents I already mentioned reading the the pilot accts on page # 3 and indeed everyone needs to stop and spend today having a ball reading these. I have taken several of these and called up several living 356th fg pilots whose official version I read to them to confirm, in most cases the pilots have these accts in their still records and it has been interesting to get a second point of coverage even if the memory cannot meet all the details of years ago. some things just stick after 61-62 years like glue

 

[GregP]

There are several reasons for the Bf 109 being harder to control at higher speeds and all were correctable. Just two of the reasons were as follows:

1) The aircraft had no rudder trim and the pilot would tire of keeping pressure on the rudder at speeds higher or lower than the trimmed speed.

2) The mechanical advantage of the control stick was smaller than some others and the stick force required to roll and pitch at higher speeds required a lot of strength ... while the fuselage and canopy area were small and did not allow much room for the pilot to move around and get some extra leverage on the stick.

Hence, a tough to maneuver aircraft. I emphasize that this was only at higher speeds. At 250 - 310 mph, the Bf 109 was superb. Then again, so was a Zero at those speeds!

A rudder trim would have been easy to add and the mechanical arm could have been altered ... but they didn't for some reason. Our museum has a Spanish Casa being put back into flying condition and the cockpit is VERY snall. Still no rudder trim! And this was post-war!

 

[mkloby]

There are several reasons for the Bf 109 being harder to control at higher speeds and all were correctable. Just two of the reasons were as follows:

1) The aircraft had no rudder trim and the pilot would tire of keeping pressure on the rudder at speeds higher or lower than the trimmed speed.

If the A/C has no rudder trim, then how could there be a trimmed speed w/ regard to the rudder? Are you referring to a factory set trim tab, or are you referring to other control surfaces?

 

[GregP]

There is always a need for rudder pressure when accelerating. One at a particular speed and in cruising flight, there is a speed where no rudder presure is required. It is usually set with a ground-adjustable tab but, in the case of the Bf 109, the vertical fin was not symmetric. It was airfoiled to fly straight at a "trimmed" speed.

Not sure what that speed WAS, but I assume it was near the natural cruising speed. This probably puts it at about 260 - 280 mph, right slap dab in the middle of it best maneuverability envelope.

If cruising faster or slower the pilot had to maintain rudder pressure in one direction or the other. If accelerating or decelerating, same story.

 

[mkloby]

There is always a need for rudder pressure when accelerating. One at a particular speed and in cruising flight, there is a speed where no rudder presure is required. It is usually set with a ground-adjustable tab but, in the case of the Bf 109, the vertical fin was not symmetric. It was airfoiled to fly straight at a "trimmed" speed.

Not sure what that speed WAS, but I assume it was near the natural cruising speed. This probably puts it at about 260 - 280 mph, right slap dab in the middle of it best maneuverability envelope.

If cruising faster or slower the pilot had to maintain rudder pressure in one direction or the other. If accelerating or decelerating, same story.

Good info. I didn't know the vert stab wasn't symmetric. I understand control surfaces and all, but I wasn't sure if it had a ground preset tab, or what exactly you were referring to. Trim is more complicated than just based off airspeed. Control surface(and hence trim) inputs are based off airspeed, acceleration, and power.

On clockwise spinning single engine birds, if you increase power, you will first need right rudder (and also forward pressure on the stick/yoke). The opposite holds true for a power reduction. If you are accelerating, you will initially need left rudder (forward stick) to stay level and balanced.

Of course, when you increase power, the right rudder needed initially is greatest at slow airspeeds, and as you accelerate, the amount of right rudder needed will decrease.

 

[Soundbreaker Welch?]

Mustang Encounter Reports.
http://www.spitfireperformance.com/mustang/combat-reports/4-schlegel-8april44.jpg

Here is what 1st Lt. Albert L. Schlegel had to say on 8 April 1944

I was flying Green One in Greenbelt Squadron. We were on course and on time when the bombers called for help. We headed south and joined them, finding them quite happy.

What? Doesn't that sound funny?

 

[Rapecq]

Hi

I'm not sure if that is true but I read that for example in Fw 190 push-rods were used for the controls instead of cables - and that's why Fw 190 easy to control even at high speed.
And therefore I have questions: how did those push-rods work (hydraulic)?? and what was the situation of controls support in Bf 109 ...

Regards,

 

[GregP]

Pushrods and Heim joints are much more fun to fly than cables. The culprit is "cable stretch." Pushrods don't stretch and feel much more "solid."

Most WWII fighters had cable-controlled rudders. Many had all cable controls. Some had pushrods for aileron / elevator and cable rudders.

Some had pushrods from the cockpit to the wing junction, and cables from there to the aileron.

A really neat modern example is the nanchang CJ-6.

It has a cable operated rudder, but the ailerons and elevator are pushrod operated. It flies extremely well. I think better than a Bonanza, which is all cable operated.

Go find one in your area and beg or buy a ride in it!

 

[Rapecq]

Hi

From:
Flying the Bf 109: Two experts give their reports Flight Journal - Find Articles
about Bf 109:

"When you maneuver above 500km/h, two hands are required for a more aggressive performance. Either that or get on the trimmer to help. Despite this heavying up, it is still quite easy to get 5G at these speeds."

"I like the airplane, and with familiarity, I think it will give most of the Allied fighters I have flown a hard time-particularly in a close, hard-turning, low-speed dogfight."

"It will definitely out-maneuver a P-51 in this type of fight because the roll rate and slow-speed characteristics are much better. The Spitfire, on the other hand, is more of a problem for the 109, and I feel it is a superior close-in fighter"

and onother one:
"At higher speeds, the P-51 is definitely superior, and provided the Mustang kept its energy up and refused to dogfight, it would be relatively safe against the 109."

One small question: why Bf 109 become heavy controllable at high speeds, while for example P-51 or Fw 190 doesn't have such problems ... ??

 

[FLYBOYJ]

One small question: why Bf 109 become heavy controllable at high speeds, while for example P-51 or Fw 190 doesn't have such problems ... ??

The size of the controls, the method of rigging and the way the control system was designed to induce a "balance" within the control system.

 

[GregP]

The P-51 is quite heavy in pitch. According to accounts, it has a stick force per "g" of about 25 - 30 piounds per g, depending on the particular aircraft. You CAN make it turn hard, but you have to pull quite hard to do so. fortunately, the seating position allows you do do this. In roll, the P-51 is MUCH easier at 400 mph than a Bf 109. The culprit is mechanical advantage.

For the Bf 109, the mechanical advantage was not enough for higher speeds, which were not in Messerschmitt's mind as normal maneuvering speeds when the Bf 109 was designed, particularly in roll. Later Bf 109s were fitted with a taller stick to give extra leverage when the real problem could have been solved by moving the fulcrum of the control stick. Unfortunately it would have interrupted the production line right when Germany could not afford to have that happen.

Same with the P-51. The stick force per g COULD have been fixed, but only at the cost of an interrupted production line. Not in the cards. After the war, used in peacetime, there was no need to relieve the stick force since the attention of the various air forces was focused clearly on jets, and not improving older piston-engined fighters currently in service.

 

[mkloby]

Good info greg

 

[Kurfürst]

For the Bf 109, the mechanical advantage was not enough for higher speeds, which were not in Messerschmitt's mind as normal maneuvering speeds when the Bf 109 was designed, particularly in roll. Later Bf 109s were fitted with a taller stick to give extra leverage when the real problem could have been solved by moving the fulcrum of the control stick. Unfortunately it would have interrupted the production line right when Germany could not afford to have that happen.

I don't think it's generally a problem with the stick - the 109 in fact (at least from F version onwards, probably on the E, too) used exactly the same stick as the FW 190, the KG 13 control coloumn. The 109Fs stick could be deflected 15 degrees each side and was .47 meter high in total - you can calculate the deflection path from that easily. The aileron linkage was provided by push rods, just as on the 190. I believe stickforces probably resulted from the aileron's design itself, but then it should be noted u to the maximum level speed of the aircraft, there were no problems with the roll rate of the aircrafts (it began to decline due to stickforces at faster speeds than achievable in level speed), unless you were in a high speed dive. However, most aircraft had restrictions imposed on the pilots not to use ailerons too much in dives for structural concerns, so this might have been intentional. Some later 109s however, from late 1943 onwards, has been fitted with aileron flettner tabs which greatly reduced stickforces at high deflection, allowing 2/3s deflection even at Mach .70 +.

The notion about the small stick travel probably stems from the British early evaluation of the 109E, but they probably refused it because they used (rather funny) types of sticks, which however had much less leverage because only the upper portion of the stick actually moved. I guess it's just a simply case of 'not invented here'.

 

[GregP]

The Me 109 may well have used the same stick. You can't calculate anything from that unless you have the fulcrum distance ... and you don't seem to have it.

The aerodynamic loads are due to aileron design considerations, airspeed load, and fulcrum. The pilot, in such a small space as a Bf 109 cockpit, sould only supply so much side force for roll. It wasn't enough to give decent roll response above 350 mph or so, at least in the Bf 109 ... and the later models were considerably faster than that, so your statement above doesn't hold up, according to history.

As for the Fw 190, the fulcrum, aerodynamic design, or cockpit leverage position were enough better to compensate. It could do aileron rolls that would tear the wings off the opposition, but wasn't too good at either instaneous or sustained turn rate. The Spitfire was great at turn rate, but was a slow roller.

Take your pick. Either can be better, depending on the pilot and the tactics.

Sorry, but late war Me 109 designs did NOT correct the roll problems, Fletner tabs notwithstanding. It was then and remains now a bad roller at high speeds.

So, the Spitfire was better than the Bf 109 when rolling at higher speeds, was always equal ro better at turn rate, and remained that way until the end of the series. I'd give the nod to the Bf 109 for armament (one in the fuselage is worth two in the wings any day). Neither of them could even come close to a P-40 at 350 mph under 15,000 feet since it rolled more than twice as fast at that speed and altitude thah either of them. Neither could come close to a P-38J or P-38L either in roll but, by that time, the war was lost by the Germans anyway, so it really didn't matter.

The history I have read by William Green, Eric Brown, and many other says the Bf / Me 109's were great airplanes, but were NEVER fast rollers at high speeds, and none mentions any significant improvements in my references. In fact, they all state quite categorically that the Bf / Me 109 was traveling in a straight line when over 400 mph and there was nothing the pilot could do about it except slow down and turn ... if he was able to do so, that is.

Vertical dives are NOT conducive to slowing down, and many went into the ground at high speed in dives.

 

[Soren]

It could do aileron rolls that would tear the wings off the opposition, but wasn't too good at either instaneous or sustained turn rate.

I don't hope you seriously believe that..

And as to the controllability of the 109 at high speeds, well you desperately need to read something other than those Allied reports - German and Finnish pilots have repeatedly pointed out that the a/c didn't become hard to control until ca.750 km/h. Pull-outs at 750 km/h was not a problem.

 

[GregP]

I seriously believe that about the Fw 190. When I hear the same thing once or twice, I may doubt it. Ten pilot reports saying the same thing get my attention. The Ta-152 turned quite well at high altitudes, but was extremely vulnerable to "regular" Allied fighters at lower altitudes ... and it had to get through the lower altitudes while ascending and descending from height. So, all we had to do was wait on it and it would come to us eventually ... same as the Me 262 and Me 163 did. Kill 'em when they land ...

I have read extensively on the Bf 109, not just William Green. All of the Allied testing I have read (including Russian tests) points to a general stiffening at anything over 350 mph, becomming almost rigid at 400 mph and above. All also indicated the Bf 109 to be excellent at 220 to 330 mph, right where it was designed to be.

That comes from multiple sources, all pilot reports I might add, and is confirmed by pilot reports from Merlin-engined Spanish 109s as well. As it happens, we have one of these at the Planes of Fame Museum in Chino, California, U.S.A. . It is being repaired after a brake failure-induced ground loop. In fact, it should be back on its own landing gear in about a month or so and should fly again around the end of the year or so. The Merlin is ready. We need it back on the gear, and some minor sheet metal repair on a wing tip. Then, all we really need is a propeller!

I have to tell you, there is not much room in the cockpit to get leverage for rolling moves. It is simply very SMALL in there!

I spend almost every weekend with WWII aircraft, mostly fighters. If I have a question, I ask the pilots that fly them every weekend. They usually know except for questions about armament. The United States FAA as well as the government really hates it if we shoot down civil aircraft while testing armament for a magazine article ... so we try very hard to avoid that.

One of the best ways to avoid it is to disarm the old fighters. Works every time! No more "down in flames ..." around here! And we have fewer wrecked aircraft on the ground to clean up after! Truly a win-win solution to the devilish problem of armament tests in civil warbirds.

It is true we don't have an airworthy Fw 190 but, then again, neither does anyone else except for a "new build" Fw 190A with a Russian Shvetsov radial in it (maybe we'll see a pilot report sometime soon ...). We DO, however, regularly fly T-6s, Spitfires (Mk IX and Mk XIV), a P-40N Warhawk, an A6M5 Zero, several types of P-51 Mustangs including a P-51B and d TF-51, F8F Bearcat, F6F Hellcat, F4F Wildcat, a P-38J Lightning, and occasionally an F3F, Hurricane, P-26 Peashooter, P-47 Thunderbolt, TBD Avenger, and SBD Dauntless. The jets also fly semi-regularly (T-33, F-86, MiG-15, TS-11). Sometimes we get a bomber up, too (B-25J).

Frequent visitors include a couple of AD-1 Skyraiders. Their R-3350 engines make an almost impossibly good-sounding rumble when running. Remember not to stand behind it at startup or you'll be rolling down the asphalt as you tumble away from the old warhorse while eating oil smoke at the same time.

 

[Parmigiano]

... Kill 'em when they land ...

.. well, that's valid for any aircraft.

Take an F15 in landing approach, gear and flaps out and no fuel left and let an average pilot bounce it with a P51, Fw190, Spit or any decently fast and armed prop fighter...

About limit performances of WW2 planes, I am afraid we will always be stuck to non conclusive discussions based on historical reports: nobody will fly a preserved 109 to her dive limits today, like nobody will race a preserved Ferrari GTO (value= $5 million) to find what really was her lap limit at Le Mans.
And even if it will happen, the engines and setup of the preserved machines will never be as 'shiny' as when they were readied for combat or real race.

There is contradictory literature about the 109 high speed performances, some say it was nearly impossible to control at high speed, some other that the 109 dived away from P51 and recovered faster.

What seems probable is that in many cases the real performances were so close that pilot skills and the specific plane could make the difference. (planes were accepted in service with tolerances higher than 5% from standard, so a 95% 109 and a 105% P51 duel was different than a 105% 109 vs 95% P51)

 

[Kurfürst]

The Me 109 may well have used the same stick. You can't calculate anything from that unless you have the fulcrum distance ... and you don't seem to have it.

Sorry if you haven't got it, but I already gave you the particulars.

The stick is 47 cms long, and can be deflected to 15.3-15.3 degrees to each side. From that the top of the stick travel can be easily calculated via simple application of trigonometry..

The aerodynamic loads are due to aileron design considerations, airspeed load, and fulcrum. The pilot, in such a small space as a Bf 109 cockpit, sould only supply so much side force for roll. It wasn't enough to give decent roll response above 350 mph or so, at least in the Bf 109 ...

and the later models were considerably faster than that, so your statement above doesn't hold up, according to history.

German tests done on a well worn 109F in late 1944 (it should be considered the 109G had more rigid, reinforced wings, so wing flexing would be less noticable) show that the aircraft could have a maximum stick deflection with 30 kg stick force, and still possess have it's peak ca.80-90 degrees/sec roll rate at ca 625 km/h TAS at 3 km altitude. That's about the maximum TAS possible for the fastest 109 variant, the K at this altitude.

Again, this is with an old F version with less stiffer wings, and no Flettner tabs on the ailerons as was done on many 109Gs. At higher altitudes, the roll rate is higher, and the stick forces are less - this is generally true for all planes.

As for the Fw 190, the fulcrum, aerodynamic design, or cockpit leverage position were enough better to compensate.

Again the FW 190 had exactly the same stick and exactly the same leverage on the stick.

Sorry, but late war Me 109 designs did NOT correct the roll problems, Fletner tabs notwithstanding. It was then and remains now a bad roller at high speeds.

This is your opinion. German testing shows the ailerons Flettners made it 2/3 aileron deflection possible at .70+ Mach speeds.

So, the Spitfire was better than the Bf 109 when rolling at higher speeds, was always equal ro better at turn rate, and remained that way until the end of the series.

Early Spitfires were definietely not, even British testing shows they can't compete at 200 mph, and at 400 mph they can achieve about the same roll rate, albeit with far greater stickforce required.

Later Spitfires are hard to judge, because no full test flight of roll rate of serial production Spitfires seem to exist. British testing, comparing Spitfire roll rate to the Mustang however shows 72 lbs stickforce is required to achieve a steady 45 degree roll rate a 400 mph IAS. The NACA concluded that 40 lbs is the maximum possible, and with that force, full stick deflection was possible up to 140 mph IAS.

However, Dave Southwood who both the original Bf 109G and (elliptic wing ) Spitfires says the roll rate of the two types is very similiar, and I believe he is probably right. High speed roll rate was not a forte of either types, but it seems it was generally OK if a bit stiff up the their level flight Vmax.

The history I have read by William Green, Eric Brown, and many other says the Bf / Me 109's were great airplanes, but were NEVER fast rollers at high speeds, and none mentions any significant improvements in my references. In fact, they all state quite categorically that the Bf / Me 109 was traveling in a straight line when over 400 mph and there was nothing the pilot could do about it except slow down and turn ... if he was able to do so, that is.

If think it says more about your references than the 109. There were definiete improvements.

Vertical dives are NOT conducive to slowing down, and many went into the ground at high speed in dives.

As did other planes.

 

[Glider]

Overall, probably the best desrcription of the Mustang would be a fair, good over-all fighter that's best quality was speed and range, and was not exceedngly great or poor in any other regard. A jack of all trades, master of none.

Totally agree with this.

 

[Juha]

Soren
What I have read on Finnish pilots opinions on Bf 109G, they tended to agree with Kyösti Karhila, FAF ace with 33 ¼ victories, whose opinion was follow:
virtualpilots.fi: WW2History-KyostiKarhilaInterview.html

Interviewer: How difficult was it to control the 109 in high velocities, 600 kmh and above?
Karhila: "The control column was as stiff as it had been fastened with tape, you could not use the ailerons. Yet you could control the plane."

IMHO a better translation is … You don't have strength to move ailerons much…

Original answer in Finnish:
Sauva oli jäykkä niin kuin se olisi teipattu kiinni, ei siinä jaksanut paljon siivekkeitä käyttää. Pystyi kuitenkin ohjaamaan konetta.

Juha