F6F, FG-1, P-51, P-47 comparison

[F4UDOA]

Diehard/Stoney,

I have an orginal copy of this report (I have the entire Symposium) from the Society of Experimental test pilots.

They did not select the P-51 as being the best, they selected the FG-1. I can post the rest of the report when I get a chance. The quote was something like "The weapon of choice was"... the FG-1.

One other point about these test that is over looked is the precondition of the test, the F6F was underweight during the test and none were full however some were under "combat weight".

[Die Hard]

Cool! Do you have a digital version that you can share with us? Or is it copyrighted?

[MiloMorai]

What does that say about the P-51's stick forces at high speed?

Guess you didn't make the connection between the comments about the instability of the P-51 loaded with fuel and my comment.

[Die Hard]

Yes, but the point of contention was the stick forces. In any case your comment didn't say anything at all about the instability; only that the P-51's engaged in combat, not what limitations the pilots had to adhere to. They also had help from P-47's  of the 390th FS which had already engaged JG11 when the 487th took off; both Sprecht and von Fassong (the old hands of the JG11 raid) were downed by the 390th FS' Jugs, not the Ponies, and the rest of JG 11 were mostly greenhorns.

From the Memoirs of 1st Lt. Alden P. Rigby on that day:

"I kicked the tires, and climbed aboard at 9:00. The plane had been warmed up, and the tanks -topped off. The cock-pit was warm, and I was ready for a comfortable ride, as I rolled into position behind the Col. The P-47s had taken off a few minutes earlier, and headed straight for the front lines below the clouds. We had just gotten the green light from the makeshift tower, when we noticed bursts of flak just East of the field. Surprise, and even shock would be an understatement. We next saw what looked like at least 50 German fighter aircraft about to make their first pass on our field. We could not have been in a worse position, unless loaded with external fuel (or bombs). We were sitting ducks, and our chances were slim and none. It was not a difficult decision to take off, since that was the slim chance. The next 30 minutes were filled with action and anxiety, that perhaps had not been seen, or felt before or since. I had turned on my gun heater switch earlier, and now had the presence of mind (and prompting) to turn the main switch on.
 
The take-off roll was very close, rapid, and somewhat organized. We did not wait for help from the tower, or our own departure Control Officer. We just went. I am certain there were a few short prayers to just get off the ground. I had my own sort of set prayer, consisting of 6 words that had been used many times. Being caught on the ground was simply a fighter pilot's nightmare. We had made the situation even worse by having our fuselage tanks filled. This would make a big difference in our maneuverability, until about 50 gallons could be burned off. This would be my first take-off ever with the gun sight illuminated on the windshield. Things were happening too fast to even be afraid, that could come later. There was no training to cover such a situation, instinct simply had to take over, and it would have to be an individual effort."

[Stoney]

When was the metal elevator with the decreased incidence in service, and how did the earlier fabric covered elevators perform?

Those two reports I posted were created with P-51s with fabric elevators.  What does decreasing the tail incidence have to do with elevator control force levels?  That's merely a longitudinal stability issue. 

[Die Hard]

What does decreasing the tail incidence have to do with elevator control force levels?

I don't know, that's why I asked.

[F4UDOA]

Diehard,

I have a copy of the entire Symposium that was performed in 1989. It contains about 350 pages on flight test done by many test pilots on everything from the B-58 Hustler to the AD-1 Skyraider. The WW2 Fighter piece is actually rather small part of the symposium. I don't know that I would be violating any copyright laws by scanning and posting the report as they did not even charge me to receive a copy I requested.

It may take me a few days to get to this but I promise I will get it scanned. I have seen incomplete versions posted around but never the entire report. Like most reports it raises as many questions as it answers.

The abbreviated version posted in this thread after reading it I have to say is really paraphrased and leaves out much critical information. Having said that it is a great piece of test data and worth mulling through again and again.

[Die Hard]

Thank you! Looking forward to it.

[Baumer]

You can purchase this paper from the society of experimental test pilots.

http://www.setp.org/

Do a non-member search and look for paper No. 1735, it will cost you $10.00 to get it.

[drgondog]

The 2000hp and 1500 hp ratings were max ratings. That means WEP.

However WEP was never used. Max continuous was used except for climb, where military was used. So basically the tests are done on cruise settings. Not exactly competitive stats at those reduced settings. Wartime testing pushed the planes more because thousands were available. Newer tests don't dare risk the multi-million-dollar assets that are almost irreplacable in this day and age.

Interesting, but not as valuable as WW2 era tests.

Your point is valid as the max potential of a 51D with a 1650-9 depended on 150 grade fuel and 100L would not yield anywhere close to Low Blower max at 10,000 feet. 1900Bhp vs 1500Bhp is huge in climb and acceleration and would help in turn.  Having said this all WWII P-51D had 1650-7 which had max 75" hg vs 90" for max 1650-9.

The part of the report that I read several posts earlier stated 1650-9 which had max TO power of 1390 Bhp with 61" and 1500Hp at 61" at critical altitude for Low Blower.  @10K the BHp ~= 1460
WEP in Low Blower at critical altitude @10,100 ft = 1930 BHp @3000 rpm, 80" (wet) but needed at least 130 grade and probably 150 to get 80"


The 1650-9 was finicky w/Bendix Stromberg Carb and often had trouble getting full potential horsepower.

[drgondog]

Thanks Widewing, that was very nice of you to do. Unfortunately it still leaves unanswered question, and brings up new ones. Are there other measured tests done on the P-51's stick forces at or near Vmax? When was the metal elevator with the decreased incidence in service, and how did the earlier fabric covered elevators perform? Do you have more friends in "high places" that might shed some light on this issue?

Thanks again!

I know from the 355th FG Histories in the Engineering section that the P-51D-20s (and K-10s) all arrived with metal elevators and the Service groups received their field mod kits which came faster than the -20s to ETO.  IIRC the metal elevators were retrofitted to all B/C/D/K starting in Aug-Sep-1944, along with reverse rudder boost.  The increased negative incidence of the horizontal stabilizer accompanied the -20 and later rero fitted to all earlier models.
The incidencs changed from 2 degrees to 1/2 degree w/metal elevators.  That should have had the effect of more 'down force' per degree AoA, thereby reducing the stick forces required to pull out of a dive - but also require slightly more nose down trim throughout the flight profile for level flight.

[Blooz]

Now let me guess.

You're new here.

[MK-84]

Loving this post...

But most of these facts reported are personal experiences from a singular pilot.

I'm told my Ford sucks and I should buy a Dodge as well based from my friends experiences...Most of these stories are opinions as a result.

We include more performance data than IMHO was likely used by a pilot in combat.

We are ignoring tactics and training of each pilot.


Even reputable pilot's accounts, only tell the story of that individual, and how he decided to fly a particular model airplane. (assuming that individual was not involved in the design and testing of said aircraft)

I would make a wild guess here   That the pilots were trained specifically to use their airplanes strenghts in combat, and mitigate their weaknesses versus their opponents.

[drgondog]

Now let me guess.

You're new here.

You are correct.  I am a pilot, an aero engineer by education, structures guy for some time before moving into Information Services, have some time in a 51D that my father bought in 59, have written Angels, Bulldogs and Dragons - history of the 355th FG during WWII and know a lot about ETO and the Mustang.

I have a hard time keeping my mouth shut, can answer a lot of questions I have seen posted and easily persuaded to move on if my presence is not welcome.  I am retired but continue to consult to augment my fetishes.

Hello.

[Stoney]

You are correct.  I am a pilot, an aero engineer by education, structures guy for some time before moving into Information Services, have some time in a 51D that my father bought in 59, have written Angels, Bulldogs and Dragons - history of the 355th FG during WWII and know a lot about ETO and the Mustang.

I have a hard time keeping my mouth shut, can answer a lot of questions I have seen posted and easily persuaded to move on if my presence is not welcome.  I am retired but continue to consult to augment my fetishes.

Hello.

Welcome to the community.  Your experience and expertise will be welcome here.  We can always use more aerodynamics and history experten...