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Blutarski2004
03-30-2005, 08:43 AM
An interesting summary -

QUOTE -

The following excerpt is from a report of the Army Air Forces Board Project No. (M-1) 50 and is a summary of how the Merlin-powered Mustang and other American fighters compared in 1943:

The P-51B, from sea level to 11,000 ft, is some seven to ten miles per hour slower than the P-51A which is the fastest fighter at this altitude. Between 14,000 and 22,000 ft. the P-51B is about fifteen to twenty mph faster. From 22,000 ft the P-51B, in high blower, widens this speed advantage up to seventy-five mph at 30,000 ft. From sea level, the P-51B gradually gains on the P-38J and the P-47D until, at 16,000 ft. it has a speed of about 420 mph which is about ten mph faster than the P-38J and about twenty mph faster than the P-47D. Above 27,000 ft, the P-51B can no longer get war emergency power, but its speed of about 430 mph at 30,000 ft is equal to that of the P-47D and about twenty mph faster than the P-38J, both using war emergency power. The P-51B is capable of 400 mph at 40,000 ft.

The P-51B is by far the best climbing aircraft of all current American fighters. It takes about 4.5 minutes to get to 15,000 ft as against five minutes for the P-38J and about seven minutes for the P-47D. The P-51B maintains a lead of about .5 minute over the P-38J to 30,000 ft and reaches that altitude in about eleven minutes which is about 6.5 minutes faster than the P-47D.

In zooming the P-51B with the P-47D from level flight at cruising and high speeds, and from high speeds out of dives, the P-51B gains speed rapidly and leaves the P-47D far behind. In zooming the P-51B with the P-38J, from level flight at cruising speed, the fighters climb evenly at the start. However, the P-51B falls off while the P-38J keeps climbing. In zooms from high speeds (425 indicated air speed), the P-51B pulls away from the P-38J and its zoom ends considerably higher.

The diving characteristics of the P-51B are superior to those of any other fighter plane. It is exceptionally easy to handle and requires very little trimming. The P-51B dives away from all other fighters except the P-47D, against which the P-51B loses several hundred feet ahead in the initial pushover and then holds that position, apparently neither gaining nor losing distance.

The new seal-balanced ailerons of the P-51B give the fighter a faster rate of roll at all speeds than any other fighter except the P-47D with which it is equal at cruising speeds.

The search view of the P-51B is better than in the P-51A but is still obstructed above, to both sides, and to the rear, by the canopy construction. The view forward over the nose is considerably improved over the P-51A by the relocation of the carburetor air intake scoop, the elimination of the clear view panel on the left side of the windshield, and lowering of the nose of the engine one and one-half degrees.

The fighting qualities of the P-51B were compared with those of the P-47D-10 and the P-38J-5 and, briefly, with the P-39N-0 and the P-40N. The only maneuver the P-39 and P-40 have that is superior to the P-51B, is a slight advantage in a turning circle. In all other maneuvers, as well as performance, they are both far inferior. The P-51B has good performance at all altitudes, but above 20,000 ft the performance improves rapidly, and its best fighting altitude is between 25 and 35,000 ft. The rate of climb is outstanding, with an average of about 3,000 ft per minute from sea level to 25,000 ft. Above 20,000 ft. the overall fighting qualities of this aircraft are superior to those of all the other types used in the trials.

- UNQUOTE

From website - http://rwebs.net/dispatch/output.asp

Ratsack
03-31-2005, 05:18 AM
Thanks for that, Blutarski. Interesting read. One thing it highlights is that rate of climb for all three types was not their strong point.

I read somewhere that Rolls Royce played with the idea of jamming a Griffon 65 motor into a Mustang, but that it never progressed beyond daydreams. Just imagine that: the Spit went from 370 to 410 mph with the 60s series Merlins, and the Pony went from 380-90 to 435-40 with the Packard versions of the same Merlins, but the Spit went from 410 mph to 440-450 with the Griffon... http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif

Could you imagine the whining in this forum if they'd actually introduced this thing? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif


Ratsack

Frequent_Flyer
03-31-2005, 07:32 AM
Ratsack,
Here's one for you, the P-47N which flew in combat and destroyed enemy aircraft had a attained 470 MPH at 30,000ft. 1800+ were produced from dec. 1944 on and flew from Siapan to Japan.In the 'flew but did'nt do much'( Ta 152) catagory the XP-47-J a lightweight version of the T-bolt utilizing the R-2800-57-c, and a cleaned up airframe, with 6 X.50's became the first prop driven fighter to exceed 500 MPH in level flight on 4 August, 1944
It gets better Republic did not put XP-47 into production because they were going to put the P-72 into production, the first fighter to be designed around the 28 cylinder Wasp Major turbo-supercharged engine. It flew on 2 Feb., 1944 with a pressuriized cockpit it reached 490 MPH at 25,000ft.to be armed with four 37mm cannons, 100 were order but cancelled in favor of the Shooting Star......Maybe a future BOB project.

Maple_Tiger
03-31-2005, 08:39 AM
That all being said,

The P-38 won the war. http://forums.ubi.com/images/smilies/35.gif

Blutarski2004
03-31-2005, 08:43 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Ratsack:
Thanks for that, Blutarski. Interesting read. One thing it highlights is that rate of climb for all three types was not their strong point.

I read somewhere that Rolls Royce played with the idea of jamming a Griffon 65 motor into a Mustang, but that it never progressed beyond daydreams. Just imagine that: the Spit went from 370 to 410 mph with the 60s series Merlins, and the Pony went from 380-90 to 435-40 with the Packard versions of the same Merlins, but the Spit went from 410 mph to 440-450 with the Griffon... http://forums.ubi.com/groupee_common/emoticons/icon_eek.gif

Could you imagine the whining in this forum if they'd actually introduced this thing? http://forums.ubi.com/groupee_common/emoticons/icon_wink.gif
<HR></BLOCKQUOTE>


..... Agreed. Another interesting what-if was the idea of using Merlins to power P38's. Roger Freeman (Mighty Eighth War Manual) makes some really impressive claims for P38 Merlin-powered performance.

Another point I came away with after reading this report excerpt is that I think there was a substantive difference in performance between the P51B/C and the P51D series in terms of terminal dive behavior. This 1943 report is talking about the P51B/C and speaks glowingly of its dive performance. The later P51D model introduced a different airfoil (among other things) and I believe that it was only at that point that dive related compressibility problems suddenly cropped up.

Blutarski2004
03-31-2005, 08:46 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><font size="-1">quote:</font><HR>Originally posted by Maple_Tiger:

Proud member of the FBAA and Nutty Philosohpy Club.
-----------------------------
The more less you'r travelling, the further back in time you go.

<HR></BLOCKQUOTE>


..... Also a proud member.

"If the world is truly spherical, what point is there to it?"

;-)

Blackdog5555
03-31-2005, 10:09 AM
The fact that the "initial pushove the P47 gains several hundred feet"! Wow..Thats what they talk about when the pilots mention diving to escape.. That is what is not modeled in the sim. BTW, ive read, some pilots like the P51B over the c and D because it was lighter and more aerodynamic.

Aaron_GT
03-31-2005, 12:51 PM
"The fact that the "initial pushove the P47 gains several hundred feet"! Wow..Thats what they talk about when the pilots mention diving to escape.. That is what is not modeled in the sim."

It isn't clear from the quotes at what speed and altitude the dives were from. The P47D at cruise at high altitude as power to spare. At maximum speed I am not sure what the difference would be. Likely it would be much less as you'd have to be getting in the mach 0.7 range, probably, for the difference in aerodynamics to really show itself. At 20,000 feet that's going to be above 500mph TAS, which is above even the maximum level speed of either plane.

I did some dive tests about a year ago based on the Fw190 and P47D from cruise, and there didn't seem to be much difference between the two, but then in real life the difference wasn't too great either, so the tests I did might not have revealed a difference.

In any case there is going to be the issue of power loading and aerodynamics mixed in.

BigKahuna_GS
04-03-2005, 10:16 AM
S!

Interesting reading. The P51B was the most maneuverable P51 model and the Corsair out climbed, out-turned, out-looped and out-rolled it. The only place the P51B was superior to the Corsair was above 25,000ft.

I wonder about the climb rates listed though. The P38 definetly outclimbed the the P51. The biggest mistake was not installing paddleblade type propellers on the P38.

Here are official performance numbers of an USAAF fighter evaluation of the P38J-10, P47D-10, P39Q-5 and P51B. The P38J-10 serial number AC42-67869 was flown by 3 pilots during a 30hour accelerated flight test on December 2, 1943.

Maximum horsepower at 60.8 inches of Hg manifold pressure, 3000rpm was listed at 1,612 brake horse power (WEP) per F-17 Allison engines. (P38 J10-LO) pg.213 "The Lockheed P38 Lightning" by Warren M. Bodie Lockheed engineer/historian.

USAAF flight test results P38J-10 :
Maximum Sea Level speed -----------------------------345mph
Maximum critical alt speed --------------------421.5mph (WEP) (25,800ft)
Rate of climb (SL) ----------------------------------4000fpm
Rate of climb (critical alt) ------------------------2900fpm (23,400ft)
Time to critical alt --------------------------------6.19 mins. (23,400ft)
Service ceiling -------------------------------------40,000ft


Here is a what if for you from Warren Bodie,

Howdy Keith,

Just imagine a Lockheed P-38N without turbos, but with the same R-R Griffons used in some of the very late high-altitutde Spitfires and also using H-S wide-blade props as demonstrated on the XP-38K. Something over 2100 hp per engine. That is why I stated that I could envision that a pilot at full throttle at 33,000 feet might well get into compressibility in level flight unless he extend the dive flaps. They might well have had to go to multi-position flaps instead of just dumping them wide open.

See. I am not yet, quite, senile. Maybe I will have to drink some senile juice on my 82nd birthday.
Warren

__

The other thing not aken into account is that many P47s were being over-boosted from late 1943 on. The 56th FG was getting P47M performance from their P47D models, otherwords close to 470mph TAS at alt.

Of course the Brits and I imagine some USAAF P51 groups were over-boosting their Mustang III's 25Lbs and getting over 400mph on the deck and 450+mph at alt.



__________________________________________________ ________________________
Arron GT-I did some dive tests about a year ago based on the Fw190 and P47D from cruise, and there didn't seem to be much difference between the two, but then in real life the difference wasn't too great either, so the tests I did might not have revealed a difference.
__________________________________________________ ________________________


Nothing could be farther from the truth Arron. There was a significant advantage in energy and dive speed for the P47 over both the 109 and 190. This difference could be used both offensively and defensively. Currently this is not effectively modeled right in AEP/PF.


Gunther Rall flew all types of German fighters when he was Commander of the Fighter Training School including the 190D9. So in fact Rall did fly the 109K4, G10 and 190D9 against captured US fighters. Rall was in an excellent position to compare first hand flight characteristics and develop tactics.

http://www.virtualpilots.fi/hist/WW2History-GuntherRallEnglish.html

Questions and Answers

Q. Did you fly many more flights at the very end of the war, 1945?

A. No, no. I flew the 109. My Wing and all the Combat Wings, we flew the 109G in those days. But when I was a Commander of the Fighter Training School, I flew the 190, the long nose 190 and all types. We were testing them. In combat I flew the 109. I will tell you, the last month, April, there was no more fighting anymore in the last year, because we didn't get any warning. You know, there was no radar station anymore. In the west, there was finito with the war already. So this was chaos.


What was important was the German Air Force had a formation of captured aircraft restored. They came for training to my fighter leader school. Certainly, I only flew the P-51, P-47, P-38 as a target for my students. So I learned these planes and I learned the advantages and disadvantages compared with the Focke-Wulf 190 and the 109. And I still consider that altogether with all these factors that the P-51 was most likely one of the best fighter planes. This was maneuverable. When I got in, the first thing, I got in the cockpit and I saw electric starting system. I remember wank, wank in Russia (refers to the manual starter by mechanics). Her (P-51) press button, prrrd, then we go (electrical starter, easy engine starter). Fantastic. Beautiful sight (visibility). We never had this sight to the back.. Very stable undercarriage. Very good weapons set. So I think this was a very good airplane. I flew it a few times, then I flew the P-47, then I discovered the speed difference, down, perfect. P-38. And I flew the Spitfire. The Spitfire was a fantastic airplane, but with a limited endurance like all the continental aircraft. So this was a good lecture for me. After that I became a wing commander of the Wing 300 (JG300). This was at the end of the war in February 1945. It was chaos. I don't talk about that anymore.
___

More Rall:

Now the big difference, talking about the airplanes we confronted. The Americans came in P-47 or P-38 or -P51. Their engines flew 7 hours with internal tank fuel, not external tank. We, and all continental aircraft, including the Spitfires, all the French planes, flew 1 hour 20. We had an external tank, but you had to drop the tank because it reduced mobility. This was a tremendous handicap against the Americans.

... came in and got to the leader of the wolf pack and got his left wing. Flames you know. With this tremendous amount of fuel you get a flame. Then I cut to the right and I was hunted. Then they chased me. Anyway, I was chased by P-47. I knew exactly that in a dive P-47 is much faster than 109. And the P-47 has a much higher structural strength. They can go up to 1400 kilometers per hour. The 109, if you go to 1000, pull it up, you risk that the wings come off. So I went down from that, bang, bang, bang. I was chased by what we call line abreast, 4 p-47s. And all that shooting here and all of a sudden bang. The left hand was on the throttle and came off and the thumb was off. Finally, I managed. This was a very traumatic thing, certainly. I pull up, when I was down, to the stalling point. The couldn't follow me because these P-47 wanted to fly back to England. And I want to get rid of my airplane. I don't care for the airplane, I want to get out of this. I managed that. This was very difficult because I was hanging outside. I couldn't operate with this hand, nothing. Finally it worked and I pulled the parachute way down and I came down safely and was hanging on a tree.


Read the whole interview :
http://www.virtualpilots.fi/hist/WW2History-GuntherRallEnglish.html


Q: Mr. Rall, what was the best tactic against the P-47?

A: Against the P-47? Shoot him down! <Laughter from both Mr. Rall
and audience, applause>

P-47 was not a big problem. The problem was if you were chased by
the P-47, he was fast in a dive, had a higher structural strength.
You couldn't stand that you know? And they came closer in a dive,
because she was faster. But P-47 was a big ship, you know? No doubt.
(Keypoint here) But in a position where you chase him, there was no equivalent condition.

In Rall's opinon as both Commander of the Fighter Training School where all types of fighters were tested including the 109K4, G10, 190D-9 and during first hand combat experience the P47 was faster in the dive. You notice that he was caught from behind by P47s while trying to escape.


USAAF Dive tests :

Part of the test-----

3) Diving

(a) 10,000-3,000ft, starting at 250mph diving at an angle of 65 degrees with constant throttle setting. The Fw190 pulled away rapidly at the beginning, but the P-47 passed it at 3,000ft with a much greater speed and had a decidedly better angle of pull out.

"However it was found the P-47 could get on the tail of the Fw190 by making a figure 8 in a vertical plane. In this maneuver, the P-47 , which was being pursued by the Fw190 in level flight attempted to execute as series of climbs, slow turns, and dives which would end up with the positions reversed and the P-47 on the tail of the FW190. The maneuver started with a steep climbing turn to near stalling point, followed by a falloff and fast dive which ended in a pullout and fast climbing sweep which again carried the plane up to the stall and fall off point.
The P-47 built up more speed in the dive than the FW190 with the result that the Thunderbolt also climbed faster than the FW190 and also higher. The P-47 pilot merely waited for the FW190 to reach its stalling point below him and turned very neatly on the tail of the falling away FW190. With its much greater diving acceleration, the P-47 soon caught the FW190 in the second dive of his maneuver."

P47 Ace Robert S.Johnson did this many times.

_______

SkyChimp
04-04-2005, 07:12 PM
Of all the performance restrictions a plane had, those affecting dive seem to be completely forgotten in this sim.

I don't know of any plane where it was recommended that a high speed dive should be started from full power. In fact, in almost every case I know, it was recommended that power and engine speed be REDUCED before a dive was entered. For instance, the P-47 pilot was told to reduced his trottle and engine speed to 2600 rpm before entering a dive. That would give a safety margin against over-rev. Diving caused engine RPMs to rapidly rise, and starting a dive at full throttle was a quick way to seriously over-rev an engine and ruin the engine, prop or gearbox. Additionally, the application of power in a high speed dive was used to assist in pullout, and if there was no throtle to apply, there was no help in that regard.

A good description of what can happen when a plane starts a dive at full throttle is in the book The JG26 War Diary, Volume Two. Uffz. Georg Genth stated that when diving his Bf-109K-4, "his cowling panels popped off and his oil lines had burst from overstraining the engine.

But no overrev effects exist in FB. In FB, in any plane, you can dive at full throttle and excessive RPM are either not modelled, or have no effect on the plane.

Aaron_GT
04-06-2005, 04:22 AM
"But no overrev effects exist in FB"

They do, certainly for the 109 series - you can blow the engines with overrev on those. Also damage to the spinner on CSP planes that destroys the governor the engine can go into overrev and be destroyed. Once I got an overrev in a dive in a Hurricane IIc. Before the dive I didn't notice any damage to the governor so it may have been due to the dive but it is possible that it may have been to damage that I just hadn't noticed at that point. So it may or may not be modelled for dives and may nor may not be modelled in a fully accurate way.

Aaron_GT
04-06-2005, 04:25 AM
"excessive RPM are either not modelled,"

Definitely are, just that CSP may keep them in check very well when working.

Also with the 109 example above, was it running with CSP (and no damage) or on manual prop control on the 109, so there are some extra possible variables that may or may not be operating with a 109. An RL example from a plane with CSP only (e.g. Spitfires in those high mach dives) would be interesting.

JG53Frankyboy
04-06-2005, 04:29 AM
at least Brewsters and FIATs do overrev in a dive.