comparing

[BnZs]

Interesting, but there are a few quibbles.

"31.            Short trials were made against the Mustang X between 20,000 and 27,000 feet, at which heights the performances of the two aircraft are most nearly related. The Mustang is designed as a low altitude fighter."

It would be rather bad if the extra weight of the Jug's turbocharger did it no good at high altitudes, now wouldn't it?  The AHII turn data was gathered on the deck however.

Also, the Mustang X was *not* the final P-51B, but refers to some test-bed aircraft for the mating of the Merlin engine and earlier Mustang variants. In point of fact, the following may be the actual individual aircraft tested

"AL975/G: First used for performance and handling trials of the Mustang I before conversion on 2 July 1942; flying for the first time on 13 October 1942. The aircraft was identifiable by a bulged lower engine cowling and was also fitted with a four-blade Spitfire Mk IX propeller. In testing, it achieved a top speed of 425 mph (684 km/h) at 21,000 ft (6,401 m)."

http://en.wikipedia.org/wiki/Rolls-Royce_Mustang_Mk.X



If you have some inkling of the weights for the Mustang X and P-47C as tested here, I would love to see them. I did come across the bit as regards the difference between 47Cs and Ds

"The P-47D-1 through P-47D-6, the P-47D-10, and the P-47D-11 successively incorporated changes such as the addition of more engine cooling flaps around the back of the cowl to reduce the engine overheating problems that had been seen in the field. Engines and engine subsystems saw refinement, as did the fuel, oil and hydraulic systems. Additional armor protection was also added for the pilot."
http://en.wikipedia.org/wiki/Republic_P-47_Thunderbolt

This alone would cause some differences in empty weight, possibly bringing the P47C more into the same ballpark with the Mustang as far as wing loading is concerned.

Also of slight interest is this part from the same report you posted:

"30.     Manoeuvrability – The P-47C was considered far superior in rate of roll to the Typhoon, and at 20,000 feet in turning circles proved itself slightly better."

Interesting. According to Mosq's turn data however, the Typhoon in AHII with *no flaps* has a sustained turn radius of 714.5, actually beating out the P-47D-11 as tested with *one notch* of flaps, which came in at at 741.6.

This is odd and seems to directly conflict with the trials you have graciously provided, but this may again have to do with the high altitude at which the trials were conducted, whereas Mosq gathered his data on the deck.

[muzik]

In January of 1943, the RAF's AFDU (Air Fighting Development Unit) conducted a trial using the P-47C against the Spitfire IX, Typhoon Ib, P-38F and the Mustang X.  Below is the results of the trial against the Mustang X.

After all this time? Really? Why didn't you tell BnZ that pages ago and why are you telling me now?  I wasn't siding with him, all I said is "I don't know..."

My position has always been that the armed services didn't (from what I can tell) make fine distinctions between the different variants of aircraft in their "tactical" reports. And that pilots aren't any less likely to believe minor myths than the rest of the human race. Which has tragically resulted in poor BnZ's life crisis.

And if this report is any indication, the fact that one Jug was tested and reported as "identical" turn performance, makes it nearly impossible to believe that some version of the Jug couldn't wind up with better turn performance.

[BnZs]

Muzik, your posts were nothing but hyperbole saying pilots didn't know what they were talking about, except when you think they knew what they were talking about. No logical consistency to be found there. By the standards you have earlier stated, this report could be tossed out as irrelevant, unless we invoke the mysterious "Muzik think it is relevant" standard. 

And if this report is any indication, the fact that one Jug was tested and reported as "identical" turn performance, makes it nearly impossible to believe that some version of the Jug couldn't wind up with better turn performance.

It is entirely plausible to me that a Jug light enough to put the wing loading in the same neighborhood could turn with a Mustang, particularly above 20K. But there was weight creep to the Jugs as time went on, as things like additional pilot armor were being added to the P-47Ds.

[BnZs]

"Turning circle
36.            The Tempest is not quite as good."
http://www.wwiiaircraftperformance.org/mustang/mustang-tactical.html

Not quite as good?

[Ack-Ack]

My position has always been that the armed services didn't (from what I can tell) make fine distinctions between the different variants of aircraft in their "tactical" reports.

I don't think they got into that fine of detail, unless that model was the definitive  of its type.  For example, in the trials it might be P-51D vs. P-47D but the P-47D could be any of the D models, with probably the best model chosen for the trial.  Same with the P-51D.  Same thing with trials done by the RAF from the reports I've seen.  Like this one comparing the Mustang III with the FW 190 and Bf109G, the report doesn't go into which Focke Wulf or Bf109G model.

Mustang III Tactical Trials

And if this report is any indication, the fact that one Jug was tested and reported as "identical" turn performance, makes it nearly impossible to believe that some version of the Jug couldn't wind up with better turn performance.

I'm sure that is something that can be found out using EM diagrams to compare each model of the P-51 and P-47, if there are EM diagrams for each and every model.

ack-ack

[Ack-Ack]

"Turning circle
36.            The Tempest is not quite as good."
http://www.wwiiaircraftperformance.org/mustang/mustang-tactical.html

Not quite as good?
(Image removed from quote.)

The only problem is we don't know what altitude the test between the Mustang III and the Tempest or any of the other planes mentioned in the trial report.

ack-ack

[hitech]

"Relative turn radius" is very plain English for the turn radii aircraft in *relatIon to one another*.  No different or more obtuse than saying that "Bob is taller than Tom who is taller than John." This does not tell you the exact height of each man, but, if true, it does give you an idea of what the ordering will be.     A ranking of turn  radius size from smallest to largest is what the diagram is trying to convey, unless the author is using the equally plain English words "turning circle" very badly. Now the author may be wrong indeed, but if so he had plenty of company. And such an assertion again begs the question, how did the Allies get it wrong when it came to two of their *own* aircraft? Why did 47 pilots recognize they should avoid turning contests with German aircraft at all costs and then forget this tactical wisdom IF the P-51s they transitioned into were even worse turners? And why on Earth would German pilots suffer the same delusion.   

WHAT IS TURN RADIUS? And no I am not being obtuse, I can tell you what the radius of a standard rate turn is, at a give speed. But the term TURN RADIUS has absolutely no meaning with out putting it in a context.
And hence Relative turn radius is also meaningless with out a context.

What turn radius are you referring to?

Here is the paragraph that goes along with the diagram.

http://www.wwiiaircraftperformance.org/sl-wade.html

Turning Circles

In circumstances where the ability to turn quickly or tightly are infinitely variable, and where two aircraft are nearly the same, such as the Tempest V and Thunderbolt II, a great deal depends on the ability of the pilots. Speed must be taken into account if the results are going to be of any real value.

For example, if a Tempest dives on a Thunderbolt with an overtaking speed of only 50 mph, the Thunderbolt will easily be able to avoid the attack by turning, although at the same speed in the hands of equally competent pilots, the Tempest will outmanoeuvre the Thunderbolt. This advantage, however, is no by any means so apparent at high altitudes, due to the greater engine efficiency of the Thunderbolt above 25,000ft.

Similarly, where low-altitude and high-altitude fighters are compared any advantage shown by the former will be reduced as the high-altitude fighter gets nearer to its best operational altitude. After taking all these considerations into account, the position of the aircraft relative to each other will be seen from the diagram.

Once again, the Spitfire maintains top place, followed by the Mustang, Meteor, Tempest and Thunderbolt. Too much regard to this order should not be paid, particularly by the individual who will angrily recall the occasion when he out-turned a Meteor when flying his Tempest. This sort of thing is inevitable, but we can only repeat that where the circumstances are common to both aircraft, these positions are not far wrong.

First prize to the Spitfire XIV.

Now if you read closely he is saying "Turning Circle" changes with alt. Hence the term "Turning Circle" is referring to sustained turn rate, and is not referring to "Turn Radius" at corner speed, which is what your point was. Hence the diagram is meaningless for your argument.

I have been pushing this point to simply show you can not freely interchange terms like "Turn Radius" and "Turning Circle", both these terms with out a context are very imprecise and really are meaningless unless you have a real definition of the term. And when trying to convince someone like me of the correctness of your idea, terms and precision and back up sources mean something. 2nd you need to understand I really have no bone in this fight. I am interested in anything showing an inaccuracy in our plane modeling. I have no desire to prove ours correct. I have a major desire to correct a model if it is incorrect. Hence statements like "I think it is wrong but no need to change it" are 100% opposite of my attitude.

The more you understand about modeling , the more you understand the complexity of modeling . Simple things like a wings area, lift and drag co's are only starting points to model an aircraft. Each piece of the plane is an airfoil creating lift and drag not just the wing. Then next thing you find is that there are an large number of conflicting data sources on aircraft.

HiTech

[Ack-Ack]

Then next thing you find is that there are an large number of conflicting data sources on aircraft.

HiTech

Just curious, in cases of aircraft with conflicting data, how do you guys choose which data to use?

ack-ack

[morfiend]

Just curious, in cases of aircraft with conflicting data, how do you guys choose which data to use?

ack-ack

  They toss it up in a vaccum and whichever 1 lands first is chosen!


   

[Wiley]

  They toss it up in a vaccum and whichever 1 lands first is chosen!


   

I always assumed it would be the data from the heaviest book.

Wiley.

[hitech]

Just curious, in cases of aircraft with conflicting data, how do you guys choose which data to use?

ack-ack

There isn't a hard and fast way. Some times other sources back another up. Some times crunching the numbers shows something obviously is wrong with a publication and we have no choice but best estimate base on normal range of values.  I've seen original reports on some planes that list a climb rate that would require more then 100% efficiency to accomplish. The reports we tend to trust the most are those that give all surrounding data and methodology of the measurements.

HiTech

[BnZs]

I do have some notion of how complex calculating flight performance is (The other sim I fool with to any extent is Meyer's X-Plane), and I appreciate the fact that (as far as I can tell) your approach is to *calculate* it, instead of saying "the plane should fly like this" and coding the program to just regurgitate that. To use that approach, and to come up with results that we all agree are very darn close to the actual tested performance numbers across hundreds of planes is a helluva achievement. I understand that you can't go tinkering with the flight model of an entire game every time someone thinks there is a slight problem with a particular plane's performance, and frankly I think your time is be better spent with new planes, the new terrain, and other things that are good for growing the game. That is my attitude.

My beef is with those who think the sim implicitly trumps the experiences of people who actually flew the darn things, and in this particular case those who think the people who raise questions about P-51 turn performance are just biased whiners without intellectual rigor. But if the P-51s turned better, it would make my 190 or Fm2 easier for the most common plane in the game to kill when I'm flying those, so it is not bias on my part either.

Now if you read closely he is saying "Turning Circle" changes with alt. Hence the term "Turning Circle" is referring to sustained turn rate, and is not referring to "Turn Radius" at corner speed, which is what your point was. Hence the diagram is meaningless for your argument.
HiTech

Actually I was thinking this chart referred to sustained turn radius, not corner speed/instantaneous turn. Can't one airplane having an advantage in power at a higher altitude also cause it's sustained turn radius to grow less than another plane which loses more engine performance at altitude?

No, was "turning circle" known to be another way of saying "turn rate" back then? If not, then it seems to me that "turning circle" is the logical choice of words for sustained turn radius, not the other performance parameters. A turn at corner speed can't very well be called a "circle" because it can only be sustained for moments in these planes. And in the case of turn rate, "turn rate" was a term they actually used then, so would it not be more sensible to simply say turn rate, or to say that a given plane turned faster, more quickly, etc?