Thunderbolt vs Mustang

Instrumentation was probably very limited through most of ww2. I would speculate there is a margin of error that increases the faster the plane gets, but also most WW2 instruments weren't designed for transonic flight. The idea of being able to maintain those kinds of speeds was also a new concept for WW2 aircraft engineers to have to work with.
Here's where it gets fuzzy for me.
Aren't IAS readings typically lower than TAS???? with the exception of flying into a head wind.
What are other circumstances that an IAS reading might be significantly greater than a TAS reading, ruling out instrument error???


Funny...when i google: "P-47D" and "critical mach", that 0.83M number pops up, which is an obvious typo. i have to dig for the actual figure.

drgondog said:

Note at the bottom of the tables is the caveat that CIAS, while corrected for instrument and calibration error, does not make provision for Compressibility.

The aircraft in this discussion all started into compressibility effects at .55 Mach. The classic definition for the start of Compressibility is the point in which the total drag rise > .0020 as Velocity/Reynolds Number increases.

At least there is a Table for P-47 results and certainly no more suspect than those for the P-51 and me 262, etc.

Based on the published methods for calculating TAS for the Me 262, I am more inclined to believe the German test results, given the lack of sensor and instrument technology available in WWII

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However, if the calculations are similar across the board, then they would be subject to the same margin of error. You might concede that the P-47D was a faster diver than the 51D. 0.85M for the p-51D which began to come apart at .80M, and 0.861M for the P-47D, which required dive flaps to recover safely.

They both liked to gleam like silver, didn't they?

I agree with most arguments here about the two. The P-51 was more vulnerable to fire, and pity it was that in the Korean War the P-47 wasn't used. Perhaps it was because of it's more traditional looking prop fighter design?

The P-51 was a terrific fighter, but it had less firepower. So it's a tossup.

Soundbreaker Welch? said:

They both liked to gleam like silver, didn't they?

I agree with most arguments here about the two. The P-51 was more vulnerable to fire, and pity it was that in the Korean War the P-47 wasn't used. Perhaps it was because of it's more traditional looking prop fighter design?

The P-51 was a terrific fighter, but it had less firepower. So it's a tossup.

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Well, I have a new desktop background.

That´s a good idea, Clay. Tnx, Soundbreaker.

billswagger said:

Instrumentation was probably very limited through most of ww2. I would speculate there is a margin of error that increases the faster the plane gets, but also most WW2 instruments weren't designed for transonic flight. The idea of being able to maintain those kinds of speeds was also a new concept for WW2 aircraft engineers to have to work with.
Here's where it gets fuzzy for me.
Aren't IAS readings typically lower than TAS???? with the exception of flying into a head wind.
What are other circumstances that an IAS reading might be significantly greater than a TAS reading, ruling out instrument error???


Funny...when i google: "P-47D" and "critical mach", that 0.83M number pops up, which is an obvious typo. i have to dig for the actual figure.

Click to expand...

Bill - first, the RAE chart is an interesting "add" - thanks for posting it.

I would like to see the detail report someday but at least this one gives calculated Cd0 and calculated M. One of the interesting anomalies is that Cd0 decreases from .859M to .861M then proceeds to the trend it should show as Mach number decreases.

Additionally the TAS in the table, if normailzed to EAS or corrected for Temp/Pressure/density is off at .861 and actually all other values of TAS.

For example the TAS for a .861M at 19,000 feet (for T=451 R) should be 610.5 mph for a M=1 of 708mph (STP) at 19,000. If the TAS of the table is truly 608mph then the true Mach no = 608/709 = .857.

At 10,000 feet the true M=1 for STP is 734.5mph (for T=483 R). The Table shows .662M for 474TAS. If 474mph TAS is real airspeed, corrected, then M= 474/734.5 which equals .645 M.

If the M=.662 is correct (not sure how this would be derived without TAS, however) the the TAS at 10,000 feet = .662 x 734.5= 486mph, not 474mph.

To your question about IAS versus TAS, there are conditions at (or below) SL in which IAS could exceed TAS - but that is about the only circumstances - when temp and density are appreciably off STP - but not at altitude for any subsonic conditions.

I did noti

That´s a good idea, Clay. Tnx, Soundbreaker.

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You're welcome.

Shiny Warbirds always look great in the sun.