P-51D maneuvrability - what it was in reality ...

[Soren]

Raises hand

NACA L-353 reports Spitfire CL max at cruise condition (2650 rpm, 3 3/4 lbs boost), gear up, flap up, ports open, as 1.68.

What does this do to the calculations?

Clmax figures with the engine running isn't valid, what we need and what we're using is free float figures. With the engine running CLmax is going to be raised quite significantly, more so by the a/c which provides the most thrust which would be the Ta-152.

 

[Sgt. Pappy]

Random question. Wondering if the CLmax of the F4U-1A/D Corsair in different flap settings was affected by the inverted gull wing.

 

[Hop]

Hop - I'd like to know where that came from....

Fly for your life, as already quoted.

Listen folks - when I hear pilots (even the greatest aces and test pilots) make statements that the aircraft is "worn out," I have to laugh. Many of these folks had little or no maintenance backgrounds and made these determinations sometimes by outward appearances and comparing one same aircraft to another.

Fair enough. However, I am not an experienced mechanic, yet give me a worn out car of the same model as the one I currently drive, and I will be able to tell if it's worn out. Sloppy steering, sluggish acceleration, worn shocks, poor brakes, all should be apparent to a driver with experience of that model.

Tuck had a lot of hours in Spitfires, and so should have known if the Spit was worn out or not.

What wears an aircraft out?

Use, I'd have thought. I can well imagine that a Spitfire in the US in the summer of 1941 would have been a popular aircraft, with USAAF pilots queueing up to have a go. The Spitfire was after all the star allied fighter at the time.

As many of us seen, in the back of each Pilot's notes or flight manual are performance numbers. If the aircraft meets those numbers that's the bench mark of performance.

Yes, but that says nothing about handling. A well maintained engine has no effect on roll rate, which is determined by the correct rigging of the ailerons. For that you have to know the droop, the tension in the cables etc. Was the Spitfire being serviced by squadron mechanics who had experience of such things? Did it even have standard ailerons for them to have experience on?

This particular Spit was shipped to the US in mid May 1941. Sholto Douglass (head of Fighter Command) complained in June 1941 that "only now are Spitfires with metal ailerons being delivered from the factory".

Don't get me wrong, I have the utmost respect for those who flew these aircraft during these tests but I think those who recorded pilot statements as a result of these test did not press for real explanations or were not technical enough to understand what the test pilot was talking about

Tuck wasn't actually involved in the tests, he left the US some months before they began. He was simply giving his opinion of an aircraft he came across.

Interesting thing is Hop, that whenever we discuss a Spitfire testing, if the results are bad, heck, even if the paint job from artistic POV is being discussed and criticized you dismiss those results by whatever means possible, but in the same time tests of crash-landed, shot down, 190's and 109's maintained and flown by untrained personel, you take as apsolute truth and perfect example of a service plane. Now that's just funny

It would be strange if it was true. It's fiction, though.

I very rarely present enemy testing of aircraft as "truth", for those reasons. If you look I did not quote German aircraft roll rates obtained by the RAE, for that very reason. Perhaps you could dig up some examples of me holding up RAE test figures for captured German aircraft as gospel truth?

So ... where are all these performance graphs located?

Try WWII Aircraft Performance

 

[Hop]

We'll assume a CLmax of around 1.45 for the Ta-152 as CLmax is going to increase slightly with AR. The Spitfire's CLmax is going to be 1.35 - Any objections ?

Yes. The RAE's response to NACA over the faults in their tests of an early Spitfire V complained of the inaccurate method they'd used to record stall speed, and gave the measured CL for the Spitfire of 1.36 on the glide and 1.89 at full throttle.

Clmax figures with the engine running isn't valid, what we need and what we're using is free float figures. With the engine running CLmax is going to be raised quite significantly

Aircraft rarely fight with their engines off. Glide performance is not really relevant to combat.

more so by the a/c which provides the most thrust which would be the Ta-152.

What on earth makes you think the Ta 152 is going to have more thrust?

Peak power output on the Jumo 213E was 2050 ps, about 2020 hp.

Peak power output on the Griffon 65 was 2200 hp.

And that's rammed power for the Griffon, static for the Jumo. Rammed power increases critical altitude, but decreases the peak power, so the difference is more than 200 hp more for the Griffon.

Speed is going to be 600 km/h, the absolute higest speed for both a/c at SL.

You're measuring turn rates at maximum speed? Sustained turn rate at maximum speed is by definition zero, and any WW2 prop fighter is not going to be able to spend long at 600 km/h if it's turning, no matter how much energy it carries into the manoeuvre.

As to 'e' (Oswald efficiency factor), well I'm guessing the Spitfire's to be abit higher despite the aerodynamic twist of the wing.

I'd guess a bit more difference in E numbers, but I'll go with your figure just to illustrate the point.

Assume a fairly moderate turn, lift = 2 x weight, speed = 450 km/h

Lift (N) = CL * area (sq m) * .5 * pressure (kg/cubic m) * velocity (m/s) squared

Spitfire: 74832 = CL*22.48*.5*1.225*125^2
CL = 0.348

Ta 152: (I don't know the weight, but I'm using 4,750 kg, correct me if it's wrong)

93100 = CL * 23.3 * .5 * 1.225 * 125^2
CL = 0.418

So at these CLs, both aircraft will be turning at the same rate. Plugging those figures into the drag equation:

Spit: CDi = (0.348^2) / (3.142*5.61*.83) = 0.008
Ta 152: CDi = (0.418^2) / (3.142*8.94*.8 ) = 0.008

The Ta has a very slightly lower CDi, but you have to go to another decimal place to see the difference. Considering the Oswald ratios are guesswork, there's not really much point.

However, that's just the coefficient of induced drag, not actual induced drag. Induced drag itself is found by multiplying by the wing area, which is a bit greater on the Ta 152.

So the Ta 152 has a bit more induced drag in an identical turn. And less power to boot.

Taking the speeds down to tight turn fighting territory, 250 km/h:

Spitfire: 74832 = CL*22.48*.5*1.225*69^2
CL = 1.14

Ta 152: 93100 = CL * 23.3 * .5 * 1.225 * 69^2
CL = 1.37

Spit: CDi = (1.14^2) / (3.142*5.61*.83) = 0.089
Ta 152: CDi = (1.37^2) / (3.142*8.94*.8 ) = 0.084

Multiplying by wing area:
Spit = 22.48 * 0.089 = 2.0
Ta 152 = 23.3 * 0.084 = 1.95

The Ta 152 has a 2% advantage in induced drag, but 10% or so disadvantage in power, which more than offsets the induced drag advantage.

Of course, we really need to know the parasitic drag figures as well for a more accurate result.

And this is against the Spitfire XIV. The real late war turner is the Spitfire IX with 25 lbs boost, which gave as much power as the Ta 152 at low altitude, but in a much, much lighter aircraft.

The Ta 152 was a fantastic turner compared to other 190s, but not on par with the Spitfire.

 

[FLYBOYJ]

Fly for your life, as already quoted.

Fair enough. However, I am not an experienced mechanic, yet give me a worn out car of the same model as the one I currently drive, and I will be able to tell if it's worn out. Sloppy steering, sluggish acceleration, worn shocks, poor brakes, all should be apparent to a driver with experience of that model.

Tuck had a lot of hours in Spitfires, and so should have known if the Spit was worn out or not.

Everything described has to do with maintenance - if the item is well maintained there should be no difference. A pilot will not necessarily know the difference be it Stanford Tuck or Chuck Yeager. Even in WW2 there was a methodology in aircraft maintenance that should of kept the aircraft maintained to established parameters.

Yes, but that says nothing about handling. A well maintained engine has no effect on roll rate, which is determined by the correct rigging of the ailerons. For that you have to know the droop, the tension in the cables etc. Was the Spitfire being serviced by squadron mechanics who had experience of such things? Did it even have standard ailerons for them to have experience on?

I was using the engine as an example.

Normal maintenance checks on most aircraft almost since the beginning of time includes cables tensions and control surface rigging (deflections). These items are routinely inspected during routine maintenance at timed intervals.

 

[Hop]

Everything described has to do with maintenance - if the item is well maintained there should be no difference.

Certainly. But if it was well maintained, why would Tuck describe it as "very tired, very sloppy"?

Even in WW2 there was a methodology in aircraft maintenance that should of kept the aircraft maintained to established parameters.

Everything I have read about the rigging of Frise ailerons is that it was a tricky business, and difficult to get right. I wonder just what support there was for the Spitfire in the US,

 

[FLYBOYJ]

Certainly. But if it was well maintained, why would Tuck describe it as "very tired, very sloppy"?

If he was here I would ask him. I've seen high time pilots complain about a perfectly good aircraft. Everything was in limits, all rigging and systems were checked and for some reason they thought there was something wrong with it and appearances always has a lot to do with it. Not being there one could only speculate - That's why you have probably seen that web page about airline pilot writing up components and the mechanics coming back with some smart @ssed remark. (#4 engine seems to be running rough - replaced running shoes)

When I read these reports about a pilot making a comment - "the aircraft flew sloppy," or "the engine was running rough," unless they could come up with some quantified reasoning behind their claim, I take it with a grain of salt....

 

[Soren]

Hop,

You've screwed up your calculations big time. And besides it is CLmax you want to be looking at, not CL in straight flight. - Unless you're under the impression that turning happens at low AoA ??

And as to thrust, well sorry but you can leave HP out of this, its actual thrust we're talking about here and the Ta-152H's new prop provided over 300 kg more thrust than the FW-190A's and with 50 less PS.

And as to the Oswald efficiency factor, what in the wolrd makes you think that the Spit's has a figure which is higher by more than 0.03 ???!

Oh and about why you only use free float figures, simple, CL changes are variable with thrust and how big a part of the wing it covers - using free float figures allows us to figure out the effectiveness of the body itself.

Anyway lets do the calculations properly - and lets even try with a lower speed figure this time to show you that it doesn't make any appriciable difference. This time I'll also do speed figures in m/s like you, but again not that it makes any difference.

Ta-152 H-1 Aerodynamics at SL

Lift:

L = 1.45*23.3*.5*1.164*125^2 = 307232.344

Drag:

Cdi = (1.45^2)/(pi*8.94*.80) = 0.0935747393
Cd0 = -Unknown-

D = 0.0935747393*23.3*.5*1.164*125^2 = 19827.0252

L/D ratio = 15.49
L/W ratio = 64.68

Spitfire Mk.XIV aerodynamics at SL

Lift:

L = 1.35*22.48*.5*1.164*125^2 = 275977.125

Drag:

Cdi = (1.35^2)/(pi*5.61*.83) = 0.124588142
Cd0 = -Not included-

D = 0.124588142*22.48*.5*1.164*125^2 = 25469.2424

L/D ratio = 10.83
L/W ratio = 71.68

____________________________

Ta-152 H-1 L/D ratio = 15.49
Spitfire Mk.XIV L/D ratio = 10.83

Ta-152 H-1 L/W ratio = 64.68
Spitfire Mk.XIV L/W ratio = 71.68

So thats 43% more lift pr. drag for the Ta-152 H-1 compared to the Spitfire Mk.XIV, and a mere 11% more lift pr. weight for the Spitfire Mk.XIV compared to the Ta-152 H-1.

Surprise surprise !! Its the same result !


So finally here's some good advice for you Hop; Stop cherry picking and stop acting like you know something you do not !

 

[AV8]

Soren, maybe you should learn to spell the word "you're" in your signature?

I wonder if there's a "coefficient of spelling?" If so, I'd probably fail it along with Soren ... Ha!

 

[AV8]

Hey Hop,

I'm with you. The only time the max CL for gliding flight is important is when the plane is landing, gliding down from height, the engine has failed, has been shot into nonworking order by either friendly or hostile fire, or has run out of gas or oil.

If any of the above happen, a nylon parachute letdown has a much better chance of survival than riding a WWII piston fighter down to the ground .. unless there is a convenient field around long enough to land safely on.

Personally, If I were investigating a piston fighter and wanted to know performance, I'd be intersted in the lift coefficient at both full power and war emergency power. The rest aren't very important to combat. Almost anyone can be trained to fly a WWII fighter in the takeoff and landing pattern safely, so the gliding coefficient of lift would never enter my mind unless I were the designer ...

Soren must be interested in which airframe is more efficient as a glider. Given that neither the Mustang, Spitfire, or Fw 190 / Ta 152 were ever intended as gliders, it makes me wonder what he is trying to analyze. Also, it is unimportant to combat.

Were you as perplexed as I was about that?

 

[Soren]

For Christs sake, correcting an old mispelling so small that I myself hadn't even noticed it You're desperate AV8, really desperate !

Anyway its quite clear you're as clueless about aerodynamics as Hop is.

The L/D ratio is EXTREMELY important in combat as its one of the dictating factors to which a/c retains energy best in turns, and which a/c that has to disengage to regain energy first. You two ofcourse are clueless about this fact.

We don't have the exact Clmax figures for both fighters at full power, if we did they would be used - but its irrelevant cause the increase in CLmax caused by the propwash would be very similar for both a/c (again something you two probably had absolutely no clue about). But since you absolutely want to address this factor I can tell you that the Ta-152's prop is larger and covers more of the wing, leading to a slightly bigger increase in CLmax.

So AV8 I'll give you the same advice as Hop; Stop acting like you know something you do not !

PS: You're a former member right AV8 ?

 

[DerAdlerIstGelandet]

Yeap he is GregP.

 

[Kurfürst]

Um, Kurfurst, you've reposted the chart that shows exactly what I said. Apart from the Spitfire at 30 lbs stick force that you've drawn in, that is.

NACA 868 shows roll rates at 50 lbs stick force for all aircraft apart from the Zero, where the force limits are unknown. The 50 lbs line for the 109 falls below all the other aircraft I can see.

Actually it's well above the Spitfire V test done by the NACA, and also the Spitfire V roll tests done by RAE, which states 71 lbs is required for a steady rate of 45 deg/sec roll at 400mph. The 3 year old 109F can manage that with 66 lbs.. As for the Zero, there's not even a roll rate curve for 400 mph.

Of course here we're comparing an. apprx. IAS conversion for the roll rate tested on a 3 year old Bf 109F without the reinforced Bf 109G wings, against tests done on new planes, probably, and no later improvements present on the Bf 109 like aileron Flettner tabs either.

No, as we have been over ad nauseum, they are tested results for the Spitfire V, given along with the Mustang and Typhoon figures by the RAE as a comparison with the Fw 190.

Brilliant, we know now that the NACA graph above is based on a RAE test of a MkV, which MkV's roll rate results are far above any other Spitfire's roll rate.

Four problems with the Naca roll figures for the Spitfire.

Like :

1, It's made by an impartial organisation
2, In a professional manner
3, It isn't high enough
4, It isn't high enough again

First, it was a very worn aircraft.
Robert Standford Tuck:

Dear Hop, you put forward a Bf 109F-2 roll rate test as gospel, and aircraft that was produced somewhere in 1940 or 1941, and was tested after 3 years of use, in the end of the 1944. And you say it's represenetative for the type.

Yet, when it comes to a Spitfire, you argue that a plane that was freshly produced in April 1941, and was immidiately delivered afterwards to the US and tested in December 1941 is not representative because the aircraft was 'worn out' for which you give us a quote from a pilot which doesn't tell if it's the same plane at all, if the comment refer to the state before or after the test, and I'd really like to see the quote in it's full context, not just a snippet. The report would have surely noted if the results would have been effected by this alleged wear, but it does not.

In any case, it's a cheapo excuse for the tested results which you don't like.

Second, it was a Spitfire Va. That's the last of the machine gun armed variants, and so didn't have the wing strengthening applied to the cannon armed aircraft.

Neither did the 109F had the 109G's wing strenghtening applied, yet somehow such considerations only apply to the Spitifre...

Dear Hop, can you answer us why do you dismiss an American test on a brand new Spitfire on the basis that it was 'worn out', and that it didn't have the wing strenghtening of later types, whereas you hold as gospel a test done a 3 year old Bf 109F that neither had the wing strenghtening of later types?

What do you think was 'worn out' more, a 109F in the end of 1944 or a Mk V in the end of 1941 ?

Va's also came from the factory with fabric ailerons, so we don't even know if the "metal ailerons" fitted were the standard production items.

..We don't...? I am sorry but this is a cheapo trick, as it's written there and you've already admited it was discussed before, so you must know it.

Again :

Desription of the the Supermarine Spitfire airplane

Name and Type : Supermarine Spitfire VA (Air Mininstry No. W3119).
Engine : R-R Merlin XLV
Weight, empty : 4960 lbs
Normal gross weight : 6237 lbs
Weight as flown for tests : 6184 lbs

Ailerons (metal-covered)
Lenght (each) : 6 feet, 10 1/2 inches
Area (total area, each) : 9.45 sq. feet
Balance area (each) : 2.45 square feet

Third, Naca published the report containing the 868 graph post war. They chose to use the RAE's figures for the Spitfire, rather than their own.

Of course but what does it prove? Nothing apart from NACA used a RAE graph in one of it's reports. NACA didn't test roll rate up to 400 mph, though I doubt RAE would, but in any case, they took their data because it covered a larger speed range.

Besides it's interesting that RAE later commented the NACA test results and considered NACA's findings regarding the rate of roll at high speeds optimistic and in no way objected the results obtained with regards of roll, neither there's a comment either that the aircraft would be worn out at all. RAE on the NACA report :

RAE seems to have actually tested the effect of clipping of wings on the Spitfire, and the findings are quite different than what the Spit cliiped/unclipped roll rates displayed on the NACA chart suggest, ie. that there would be a linear huge rate of roll increase at all speeds. Quite the contrary, ie.

Or let's see the aspect that the clipped winged Spit V on the NACA 868, if the results are true, should roll quite easily with the FW 190A. Compare it with the pilot interviews done with Spitfire pilots when clipped wings were introduced :

Or compare another RAE trial with a Spit V with the Spit V on the NACA 868 :

Ie. the NACA 868's Spit V roll rate seems to be around 40 degrees/sec with 50 lbs stick force. However, the other RAE Spit V roll rate data shows that for 45 degrees rate of roll, 50% higher stickforce is required.


To put the long story short, the NACA 868 Spitfire roll rate curves are in conflict with every other roll rate test made for the Spitfire, either by the British, Americans.

That means either the tested aircraft was an exceptionally good example of it's type, or perhaps a testbed with some experimental aileron fitting.

Fourth, the RAE tested the roll rates of the Spitfire against other aircraft. We'll leave out the fact they said it rolled much better than the 109s, because you will just come out with excuses that they couldn't fly the 109 properly.

The RAE, Hop? Are you sure you're not making this up?

Hop, pilots who flew actual examples of the 109G and Spitfire have to say this:

Roll performance is similar to a Hurricane or elliptical wing tipped Spitfire. A full stick roll through 360 degrees at 460kph takes 4 to 4.5 seconds without using rudder, and needs a force of around 20 lbf. One interesting characteristic is that rolls at lower speeds entered at less than 1g, such as a roll-off-the-top or half Cuban, have a markedly lower roll rate to the right than to the left. Therefore, I always roll left in such manoeuvres.

Ie. Dave Southwoods words, the full one can be read at the 109lair.

Hop we all understand that in your eyes, the Spitfire did everything better than any other aircraft, it had greater mileage than the Mustang, dived to greater speed than the P-47, rolled with the FW 190, not to mention your latest theory I've read that the RAF was doing a lot more combat against the Luftwaffe than the USAAF in the late 1943, and above it did everything better than those pesky Bf 109 that still shot it down in rows for some odd reason!

But please, try to stick to reality.

But they also tested against a range of American aircraft, which they used extensively, and with manufacturers support.

This is quite irrelevant to the subject I think.

 

[Hop]

Hop,

You've screwed up your calculations big time.

Actually Soren I've got my calculations correct, because I am using the correct units. You got yours wrong because you mixed the units.

And besides it is CLmax you want to be looking at, not CL in straight flight.

Firstly, it's not CL in straight flight, unless you believe a plane flies straight whilst generating twice as much lift as it weighs.

And Cl max is a maximum turn, riding the stall. If I used your original figure of
a turn at 600 km/h, we'd get rather a sharp turn.

The problem with your new calculations is that the planes are turning at very different rates. The Ta 152 is generating 6.6 times its own weight in lift, the Spitfire 7.4 times its own weight. The Spitfire is therefore turning much tighter in your comparison.

And as to thrust, well sorry but you can leave HP out of this, its actual thrust we're talking about here

Thrust is just power multiplied by prop efficiency, so you most certainly cannot leave out HP.

and the Ta-152H's new prop provided over 300 kg more thrust than the FW-190A's and with 50 less PS.

Source for this claim?

It might be true that at some specific speed the Ta 152 prop was much more efficient than the 190A's; I've heard anecdotally that the 190 A had very poor efficiency at very low speed, probably caused by not enough pitch adjustment. But if it is true that's due to a problem with the 190's prop, not due to any remarkable breakthrough in the Ta's.

Prop efficiency was pretty similar between the allies and the Germans, if you want to claim that the Ta's was that much more efficient then you really need to provide a source, not just state your opinion as fact.

And as to the Oswald efficiency factor, what in the wolrd makes you think that the Spit's has a figure which is higher by more than 0.03 ???!

What in the world makes you think it's not? The truth is you are just guessing, and forgive me for pointing out that it's just guesswork.

Oh and about why you only use free float figures, simple, CL changes are variable with thrust and how big a part of the wing it covers - using free float figures allows us to figure out the effectiveness of the body itself.

Which would of course be a more accurate way of doing things if we were trying to work out the best turnfighter with engine off. With engine on, though, the CL is very different, and planes tend to fight with engine on (and on max, usually).

That's why the RAE also gave the CL max figure for the Spitfire at full power. The figure for the Spitfire XIV will of course be a bit different, but it's going to be far closer to the power on figure for an earlier Spit than it is to the same earlier Spitfire's power off figure.

This time I'll also do speed figures in m/s like you, but again not that it makes any difference.

It does of course because it allows you to work out how tightly they are turning. That's the sort of reason they use consistent figures in equations.

Surprise surprise !! Its the same result !

It is, but of course we can now use adjusted CL figures to get the same turn rate for both planes, rather than working out a turn in which the Spitfire is turning much tighter than the Ta.

I'll use your figures, even the non standard pressure:

Ta 152 - lift = 6.6 times weight

Spitfire - 37418 = CL*22.48*.5*1.164*125^2 = 247357
CL required to match Ta 15 turn = 1.21

Cdi:
Ta 152 0.0935747393

Spitfire: Cdi = (1.21^2)/(pi*5.61*.83) = 0.1

Drag:

Ta 152 = 19,827

Spitfire = D = 0.1*22.48*.5*1.164*125^2 = 20,443

The Spitfire has about 3% more induced drag, and at least 10% more power.

So finally here's some good advice for you Hop; Stop cherry picking and stop acting like you know something you do not !

Soren, there are few as cringe worthy as watching someone who has got things wrong mistakenly criticising something that's correct, and doing it in a patronising tone.

Next time, do the maths properly (which means using the correct units), work out the results with both aircraft pulling the same turn, and don't make assumptions like more power doesn't mean more thrust.


Brain, you accused me of hypocrisy. I asked you for some evidence to support such a charge. You haven't provided any. I'll ask again. Some evidence please, or an apology. Either will do me.

 

[Hop]

Brilliant, we know now that the NACA graph above is based on a RAE test of a MkV, which MkV's roll rate results are far above any other Spitfire's roll rate.

No, it's above earlier Spitfires. We know from AFDU tests that the Spitfire rolled as well as the P-47, and better than the Mustang, so we know that the figures you are trying to sell as representative cannot be true, otherwise how could they say the Spitfire rolled as well as the P-47 and better than the Mustang?

There's also the Dave Southwood comment you keep posting:

A 1g 360 degree full stick roll in a clipped wing Spit IX at 250 KIAS and 5000 ft takes 3 seconds

That is of course 120 deg/sec at 288 mph, which is a bit better than NACA 868, because roll rate increases with altitude, even at the same IAS.

Like :

1, It's made by an impartial organisation
2, In a professional manner
3, It isn't high enough
4, It isn't high enough again

In other words you can't actually refute the argument? Not surprising, really, as they are all facts.

Dear Hop, you put forward a Bf 109F-2 roll rate test as gospel, and aircraft that was produced somewhere in 1940 or 1941, and was tested after 3 years of use, in the end of the 1944. And you say it's represenetative for the type.

It contains the best figures I know of the 109 roll rate. And actually YOU have been posting it around the net. eg ROLLRATE TESTING: Bf109K - Topic Powered by eve community

I based my acceptance of it on your attitude, as you claim to be something of an expert on the 109.

Yet, when it comes to a Spitfire, you argue that a plane that was freshly produced in April 1941, and was immidiately delivered afterwards to the US and tested in December 1941 is not representative because the aircraft was 'worn out' for which you give us a quote from a pilot which doesn't tell if it's the same plane at all, if the comment refer to the state before or after the test,

I believe he does tell us it's the same plane, and it is obviously before the tests because Tuck saw it in the autumn of 1941, and was back in the UK before the end of the year. NACA note the tests began on the 30th December, iirc.

Dear Hop, can you answer us why do you dismiss an American test on a brand new Spitfire

How is it brand new if it had its first flight in April, and tests began right at the end of December? As Tuck said, "almost every pilot in the air corps had had a go on her", which is probably not much of an exaggeration for a Spitfire in the US in 1941.

What do you think was 'worn out' more, a 109F in the end of 1944 or a Mk V in the end of 1941 ?

Depends on maintenance, doesn't it. I imagine the Germans knew exactly how to rig the 109, I'm not so sure the US mechanics in the US in 1941 were as familiar with the Spitfire.

I don't take foreign tests of aircraft as gospel because they usually show very different performance figures, which is your position when foreign tests show German aircraft doing badly.

.We don't...? I am sorry but this is a cheapo trick, as it's written there and you've already admited it was discussed before, so you must know it.

Again :

Desription of the the Supermarine Spitfire airplane

Name and Type : Supermarine Spitfire VA (Air Mininstry No. W3119).
Engine : R-R Merlin XLV
Weight, empty : 4960 lbs
Normal gross weight : 6237 lbs
Weight as flown for tests : 6184 lbs

Ailerons (metal-covered)

No, we know the ailerons were metal covered. We do not know if they were the standard metal ailerons fitted to most Spitfire Vs, and all later Spits. The dates suggest the Spitfire in question would not have been produced with metal covered ailerons, and it was transferred to the US within days of being produced.

The problem is, metal ailerons were not standard on the Spitfire in April 1941, as Sholto Douglas points out.

We also don't know if metal ailerons required different aileron circuit rigging, and if so, if it was done on this Spitfire.

That's the disadvantage of foreign testing, which is usually conducted without the proper manufacturer/operator support.

Of course but what does it prove? Nothing apart from NACA used a RAE graph in one of it's reports. NACA didn't test roll rate up to 400 mph, though I doubt RAE would,

You doubt they would what? Test up to 400? As they clearly say the results are as tested, then they must have. As they criticise NACA for only testing up to 295, and neglecting the "vital region around 400 mph", then it would be rather silly of them not to do so themselves.

RAE seems to have actually tested the effect of clipping of wings on the Spitfire, and the findings are quite different than what the Spit cliiped/unclipped roll rates displayed on the NACA chart suggest, ie. that there would be a linear huge rate of roll increase at all speeds. Quite the contrary, ie.

Well, they went on to clip large numbers, so they must have found some benefit. They also note that there is a large benefit on those Spitfires with heavier than average ailerons, which suggests NACA 868 actually shows the results for a poor example.

Or compare another RAE trial with a Spit V with the Spit V on the NACA 868

Which Spitfire V? Would this by any chance be another Spitfire Va? And would it be an earlier test than the one published in NACA 868? I suspect the answer is yes to both.

That means either the tested aircraft was an exceptionally good example of it's type, or perhaps a testbed with some experimental aileron fitting.

Only they quote it as representative of the Spitfire in the Fw 190 test.

The RAE, Hop?

Sorry, my mistake. AFDU. Happy?

Roll performance is similar to a Hurricane or elliptical wing tipped Spitfire. A full stick roll through 360 degrees at 460kph takes 4 to 4.5 seconds without using rudder,

Of course, if you look at the graph you will see the 109 is similar to the Spitfire around the 460 km/h (280 mph) mark. There is very little to chose between them at those typical display speeds. I make it about 3 deg different, according to NACA 868 and the German figures you have drawn on.

It's when you go faster or slower the 109 shows itself to have extremely poor aileron control, as shown by these reports, and by anecdotal evidence from the war years.

Hop we all understand that in your eyes, the Spitfire did everything better than any other aircraft, it had greater mileage than the Mustang, dived to greater speed than the P-47, rolled with the FW 190,

No Kurfurst those are your lies, not things I have claimed (apart from the mach speeds vs P-47).

not to mention your latest theory I've read that the RAF was doing a lot more combat against the Luftwaffe than the USAAF in the late 1943,

See for example the Fighter Command War Diaries.

This is quite irrelevant to the subject I think.

What, you mean the fact that in comparison trials the Spitfire was found to roll as well as the P-47, and a bit better than the Mustang? Hardly, as it gives the lie to your claims.

But, seeing as you are now claiming that foreign testing of aircraft is to be taken at face value, here are the AFDU trials against 109s:

The Spitfire XIV rolls much more quickly.

.Here again the Spitfire has a marked advantage at all speeds.

Now personally I take such tests with a grain of salt, not that they are necessarily wrong, just that they can't be relied on. But as Kurfurst insists such tests can be relied on...

 

[Kurfürst]

So, I can summerize your POV, you dismiss every single Spitfire roll test done by the NACA, RAE, the RAAF, the RAF, except the single test that's details and conditions are unknown but are the most favourable to the Spitfire and in disagreement with the findings of other tests by the same organisation, RAE?

Also, you definietely struggle to dismiss a test done on a Spitfire V, on the basis that it's metal ailerons were not metal aileron, US mechanics were probably jerks anyway, the aircraft was 6 months old when tested, and it didn't have the wing strenghtening of the later models.

Yet, you want to push forward a roll test on a 3-4 year old 109F-2, which didn't have the wing strenghtening of later models either, as a gospel ?

Is that correct?

Well, they went on to clip large numbers, so they must have found some benefit. They also note that there is a large benefit on those Spitfires with heavier than average ailerons, which suggests NACA 868 actually shows the results for a poor example.

 

[bomber]

guys... I'm modelling the flight model of a Spit V for Targetware flight sim..

I used the testing report found on this site... if however there's some doubt as to it's validity/accuracy could you point me in the direction of an indepedant test.. maybe a Rolls Royce Hucknall one if they did one.

Also the engine torque gives a pronounced anti-clockwise rotation, was the time taken for this rotation ever recorded ?

And whilst I'm at it... would the ground crew not attempt to dampen this torque down with adjustments to centre stick aleron deflection ?

Regards

Simon

 

[Soren]

Actually Soren I've got my calculations correct, because I am using the correct units.

What a big load of rubbish Hop - you need to learn math !

You got yours wrong because you mixed the units.

Huh ?!! I dare you to point it out !

Yeah thats right, there has been no mixing of units at all !

Firstly, it's not CL in straight flight, unless you believe a plane flies straight whilst generating twice as much lift as it weighs.

Wow ! And just when I thought it couldn't get any worse with your wild imaginations !

Listen Hop, a CL of 0.5 is not something you get whilst turning goofball, and that silly remark of yours just supports the fact that you know nothing of what you're talking about.

Oh and btw generating a 2:1 lift to weight ratio is very normal in straight flight - so yes I do believe that. But hey keep it coming Hop, this is funny

The problem with your new calculations is that the planes are turning at very different rates. The Ta 152 is generating 6.6 times its own weight in lift, the Spitfire 7.4 times its own weight. The Spitfire is therefore turning much tighter in your comparison.

There is no problem with the math I presented, the problem lies with you Hop and your total lack of knowledge on aerodynamics. The Spitfire isn't turning much tighter at all, its got an 11% percent advantage in lift pr. weight which gives it a slightly higher initial turn rate, however the much higher drag makes sure that this advantage goes instinct quickly and is completely overtaken by the Ta-152H which holds an advantage in sustained turn rate over the Spitfire.

What in the world makes you think it's not? The truth is you are just guessing, and forgive me for pointing out that it's just guesswork.

Wrong again Hop !

I'm not just making wild guesses here, I'm basing my assumption on the 'e' figures in a graph comparing high AR wings of the same shape as the Ta-152's with a fully elliptical wing with no twist.

It does of course because it allows you to work out how tightly they are turning. That's the sort of reason they use consistent figures in equations.

You just can't stop with your ever deeeper quest into denial can you ?!

Its there right infront of you man ! The exact same difference in percentages as when I used km/h instead of m/s !

For crying out loud !

And as to pressure - at SL at 15 Celcius it is 1.164 exactly. Oh and btw, using different pressures in the equation doesn't change anything between the Ta-152 and Spit.

Source for this claim?

But ofcourse:


And I repeat: Hop, stop cherry picking and stop acting like you know something you do not !

 

[Jackson]

Hop and Kurfirst..

you make excellent points..


KEEP UP THE GREAT WORK



I believe everyone knows the Spitfire was way more manueverable than the 190 or the 109

 

[Hop]

You got yours wrong because you mixed the units.
Huh ?!! I dare you to point it out !
Yeah thats right, there has been no mixing of units at all !

You used Km/h instead of m/s. That gives you the wrong result.

Listen Hop, a CL of 0.5 is not something you get whilst turning goofball, and that silly remark of yours just supports the fact that you know nothing of what you're talking about.

Um, you can turn at different rates. You can most certainly turn at a CL of 0.5, if that provides more lift than you need for level flight.

Oh and btw generating a 2:1 lift to weight ratio is very normal in straight flight - so yes I do believe that.

Um, do you understand physics at all? If lift exceeds weight, the plane is going to be moving in the direction of lift.

There is no problem with the math I presented, the problem lies with you Hop and your total lack of knowledge on aerodynamics. The Spitfire isn't turning much tighter at all, its got an 11% percent advantage in lift pr. weight which gives it a slightly higher initial turn rate,

No. If you are generating more lift/weight, you are pulling more G. Go and look up the concept of bank angle and G.

In the example you gave, the Spitfire was pulling 7.4 G, the Ta 152 6.6 G.

Wrong again Hop !

I'm not just making wild guesses here, I'm basing my assumption on the 'e' figures in a graph comparing high AR wings of the same shape as the Ta-152's with a fully elliptical wing with no twist.

In other words, you are guessing. You don't have Oswald efficiency figures for either aircraft, just rough figures for similar wing shapes.

Its there right infront of you man ! The exact same difference in percentages as when I used km/h instead of m/s !

The percentage difference is there, but absolute figures are not.

And as to pressure - at SL at 15 Celcius it is 1.164 exactly.

International standard atmosphere density is 1.225 at sea level. It's not worth arguing over, though, as your figure isn't "wrong", just non-standard.

Oh and btw, using different pressures in the equation doesn't change anything between the Ta-152 and Spit.

No, and I never said it did. That's why I used it with the figures you'd created, rather than recalculate.

So, I can summerize your POV, you dismiss every single Spitfire roll test done by the NACA, RAE, the RAAF, the RAF, except the single test that's details and conditions are unknown but are the most favourable to the Spitfire and in disagreement with the findings of other tests by the same organisation, RAE?

No. I just generally believe that later tests tend to show a more accurate picture for later aircraft. Especially as the AFDU findings make no sense when using the figures you are trying to portray as typical for Spitfires, but do make sense compared to the figures in NACA 868.

Now, as to the question of why the earlier figures are different to the later ones, I believe I have found the answer, or at least a partial answer.

There is an earlier test of the Spitfire roll rate by the RAE, dated April 1941. They say that 65% of the aileron effectiveness is lost to wing twist, exactly the same figure the RAE reported to NACA. The report also says that due to wing twist, the aileron reversal speed was 475 - 480 mph.

The later test, the one that produced the figures you hate so much, notes that reversal speed is 580 mph for the standard wing, 660 mph for the clipped wing.