P-47D and Spitfire Mk9 turn performance

[JtD]

The 388 you quote were measured by the AAE and the aircraft was also tested by Rolls Royce, but not the manufacturer.

 

It's interesting nonetheless that you claim that 25lb boost came with serial production machines in October 1943 already, as opposed to the tested example being a testbed for the modifications.

[Kurfürst]

The 388 you quote were measured by the AAE and the aircraft was also tested by Rolls Royce, but not the manufacturer.

 

Wasn't Rolls Royce the manufacturer of the Merlin 66?

 

It's interesting nonetheless that you claim that 25 lb boost came with serial production machines in October 1943 already, as opposed to the tested example being a testbed for the modifications.

 

I am sorry but you need to re-read my post, as I did not claim any such thing. What I wrote and meant was that the Supermarine Spitfire Mark IX. Low-Fighter, serial no. JL 165 was a serial production machine, used for testing by the manufacturer of the aircraft's engine, that is, the Rolls Royce aero engine company.

Edited December 23, 2014 by Kurfürst

[JtD]

Wasn't Rolls Royce the manufacturer of the Merlin 66?

Yes, but not of Spitfire JL.165.

 

I am sorry but you need to re-read my post, as I did not claim any such thing. What I wrote and meant was that the Supermarine Spitfire Mark IX. Low-Fighter, serial no. JL 165 was a serial production machine, used for testing by the manufacturer of the aircraft's engine, that is, the Rolls Royce aero engine company.

Just pointing out that JL.165 was either a testbed for 25lb testing, or 25lb was serial production standard at the time, can't have both. Same thing as with the SU pump.

[MiloMorai]

BS.543 was built as a Mk V, converted to Mk IX (Merlin 61) at Rolls Royce, Hucknall. First flight 22-10-42. Transferred to AFDU, Duxford 8-11-42; AAEE, Boscombe Down 13-12-42 with Merlin 66 installed; Vickers Armstrong 22-2-43; 403 Sqdn. 9-6-43; 611 Sqdn. 10-6-43; 485 Sqdn. 6-7-43. Failed to return from operations 22-8-43.

 

BS.543 prototype w. experimental propeller and overly rich mixture

I could find no reference to an experimental prop and overly rich mixture. Certainly not a prototype a/c as it FTR on a combat mission while with 485 Squadron.

 

BS.310 serial production aircraft - 404 mph at 19500 ft

Max. level speed at full throttle height in F.S. supercharger gear, 405 m.p.h. (at 25,400 ft.)

 

BS310 was powered by a Merlin 70 engine.

 

JL165 @ 18lb - 20,000ft 397mph

 

3% of 404mph is 12mph (392mph to 416mph)

[Kurfürst]

Just pointing out that JL.165 was either a testbed for 25lb testing, or 25lb was serial production standard at the time, can't have both. Same thing as with the SU pump.

 

Is it possible perhaps that for the sake of testing, they took a stock Mark IX with a Merlin 66 engine with a Bendix carb and set to the standard +18 lbs, and then modified it with a SU injection unit / modified boost regulator allowing +25 lbs..? Like Messerschmitt AG did when they took a stock 109G-1, the serial no. 14 026, and then re-fitted it with a taller tail unit, replaced one of the radiators with a different unit, fitted a fixed tail wheel, a radiator position indicator and swapped the stock DB 605A for a 601E of the 109F? After all, that's the very definition of a testbed.

 

Or when DB AG took a stock serial production Mark V, stripped the Merlin out of it and bolted on a 605A under the hood from a Me 110...? Or it was production standard at the time, and there existed Spitfire Vs with DB 605As in serial production, and can't have both in existence?

Edited December 23, 2014 by Kurfürst

[MiloMorai]

JL165Vc

CBAF M45R-RH Cv LFIX M66 27-3-43 special eng for dev of injector pump carburetter AAEE 12-11-43 trials of eng at +25lb boost (Basta) and four blade Rotol prop 150 Octane fuel. Cool trials 12-43 to 1-44 AST 3-6-44 6MU 26-10-44 82MU 10-11-44 Guinean 22-12-44 Casablanca 15-1-45 Middle East 19-7-45 SOC 28-8-47

[JtD]

Is it possible perhaps that for the sake of testing, they took a stock Mark IX with a Merlin 66 engine with a Bendix carb and set to the standard +18 lbs, and then modified it with a SU injection unit / modified boost regulator allowing +25 lbs..? ... After all, that's the very definition of a testbed.

It's good then - you don't have to uphold that anything faster than 404 was a testbed and everything slower was serial production, seeing that now you're rightfully putting SU pump mod and 25lbs boost mod into the same category, whichever label it may carry. I'd label both of them testbeds, but that's just me.

[Kurfürst]

It's good then - you don't have to uphold that anything faster than 404 was a testbed and everything slower was serial production, seeing that now you're rightfully putting SU pump mod and 25lbs boost mod into the same category, whichever label it may carry. I'd label both of them testbeds, but that's just me.

 

The only problem is that no test seem to exist for serial production aircraft that would even reach 404 mph, they are rather more in the 390-395 region - BS 310 may be stretching it a bit since we do not know the testing conditions.

 

But that's OK, I suppose the RAF had its reasons to accept BS 310's 404 as a sort of nominal spec, from which serial production a/c may differ up or down by 3% due to production tolerance.

[MiloMorai]

BS310

IX 3321CHAM61FF 31-8-42 VAWD 11-11-42 comparison trials of temperate and trop air intake and filter M66 install brief perf trials 1-3-43 CRD WD 22-5-43 RM9SM torsional stiff tests of mod oleo leg links 31-8-43 AAEE 31-10-43 CG tests with different props and M70 FXII rud and FVIII pilot head install 12-11-43 CG tests hand trials 3-44 trials to det effects of high Mach numbers in dive and recovery with eng/prop combinations AST 4-4-44 major repair 83GSU 19-8-44 453S Missing nr Arnhem 27-9-44

 

BS310 saw operational service.

[JtD]

The only problem is that no test seem to exist for serial production aircraft that would even reach 404 mph, they are rather more in the 390-395 region...

If you were to look for serial production aircraft performance, you'd have to look at serial production aircraft testing, not development and type testing. Not much of those around for the Mk.IX, I'm afraid, and also not really the point of this topic.

[Pilum]

Crumpp, even though you have not responded to the question of what altitude the charts in post #1 are for, now that you posted your estimate for 30,000 ft, it can actually be reverse engineered based on that data:

 

For comparison, these are my C++ simulation results:

 

Spitfire Mk9 +18 boost at sea level: 290 KEAS, 20,000 ft: 258 KEAS and at 30,000 ft : 213 KEAS

 

P-47D-10 with D-22 prop at sea level : 290 KEAS, 20,000 ft : 263 KEAS and at 30,000 ft : 239 KEAS

 

Comparing the turn rate chart in post #11 which states 30,000ft, this gives the Spitfire maximum KEAS speed at circa 215 KEAS and the P-47 speed at circa 240 KEAS. i.e. in good agreement with my simulation numbers for 30,000 ft. Based on this it is obvious that your charts in post #1 are not sea level but for 20,000 ft since the zero turn rate speed in your charts tally with my 20,000 ft results.

 

So to conclude: Mine and JtD’s TAS based estimate for the P-47D-22 max sustained load factor at 20,000 ft is around 2.1 at 175 KEAS while your’s using your EAS method can be read off at 3.5 in your chart. In addition, JtD posted an estimate of a max sustained loadfactor of 1.8 at 30,000 ft in post #14 which tabs well with my C++ simulation result of 1.77 which in turn can be compared with your 2.4 g estimate.

 

In addition, your charts in post #1 indicate that the P-47 will outturn the Spitfire at 175 KEAS at 20,000 ft which also seems wrong and is the opposite of what my C++ simulations show.

 

So it seems there is a fundamental flaw somewhere in the way you use EAS to estimate turn performance Crumpp.

[Pilum]

<snip>and also not really the point of this topic.

 

Exactly, so maybe we can return to the topic?: P47 versus Spitfire turn performance?

 

Would be a shame if this thread derailed before we concluded that discussion.

[Friedrich-4B]

A NACA report on the P-47D-30 should be of interest: (NB: The full title is FLIGHT MEASUREMENTS OF FLYING QUALITIES OF A P-47D-30 AIRPLANE (AAF NO 43-3441) TO DETERMINE LONGITUDINAL STABILITY AND CONTROL AND STALLING CHARACTERISTICS.)

Edited December 23, 2014 by Friedrich-4/B

[Gooseneck]

Just as long as any errors aren't corrected by an amateur, I'm good. But I bet someone produces a graph which demonstrates admirably how the P-47 could out-turn a Spit. And how a 109 could too. As for the Hurricane, well everyone knows that it was easily outclassed by a Stuka.

 

bitch, moan, bitch etc. :D

 

Happy Christmas Gents. :)

[MiloMorai]

The official specs for the Mark IX.L.F. was an 404 mph, probably based on the BS 310 testing results, with a tolerance of 3 %. None of the serial Mark IX LF tests apart from the BS 310 trials referred to in other docs (w/o the testing details) I have seen ever managed to reach these official specs - all other testing of actual serial production machines yielded top speed results in the 390 - 400 mph range, i.e. trials by R-R, RAAF, and VVS.

Please note the source and the 445mph for a idealized production Spitfire IX. Maybe the previous 6 pages of the document can be posted.