quote:

=(.....@400+ IAS

Couple of issues in General with NACA 868 that I don't think is very well understood. A good example is the case of the Mustang/FW190 the information is transcribed from an RAE report which gives the same information in EAS. EAS is also termed "perfect IAS" by engineers so it is acceptable to use it as such. Is all the data transcribed in NACA 868 EAS? I don't know and it really does not matter because the purpose of the report is achieved. It was never intended to be a roll rate comparison for gamers.

If your goal is a roll rate comparsion, well then it does very much matter if the speeds were properly converted.

Viper points it out in his post earlier in the thread. That report is not a comparison of maximum roll rates, it is a comparison of lateral control systems. That is a big difference in concept and scope.

In the case of EAS at 10,000 feet, our TAS speed is ~465 mph and well beyond both aircrafts sustainable envelope. Now our airframe limits at Va assume loads on ONE axis only. Using two axes on recovery considerably lowers our limits, so high speed and multiple axis input is a great way to die in real life.

It is like looking at a coefficient of drag from one specific source and thinking it has universal application.

The report is very useful if you know what you are looking at and more importantly understand what questions the data is designed to answer. If you don't understand that you will make conclusions that are just not there to make.

All the best,

Crumpp

quote:

Using two axes on recovery considerably lowers our limits, so high speed and multiple axis input is a great way to die in real life.



Crumpp

Haa..

Im glad you mentioned this.

quote:

Im glad you mentioned this.

It makes a difference to the utility of the trait.

Keep in mind that the aileron design of the FW190 has a wide variation of performance.

It goes back to the point Bremspropeller made earlier:

quote:

To put it differently:
It had the best roll-rate of all fighters in a speed-range at which 95% of all engagements took place.

The helix angles of the P51 and FW190 control systems match at about 340IAS which means that given rigging variations I am sure that some P51's were more agile than some FW190's at high velocity in the sustainable envelope.

There is a very tiny 4% difference in helix angle between the FW-190 and clipped wing Spitfire. Given the variation in rigging we can say too that some clipped wing Spitfires were equally as agile at low speeds and some were not.

Keep in mind the effect on helix angle for the hinging changes in the P47 series. Like all aircraft, the FW190 was improved and had the hinge point moved three times along with design changes.

You cannot make a blanket statement of absolutes on the information given in the report.

As a general performance trend, Bremspropellers statement holds true.

All the best,

Crumpp

Isn't it true that p-51s were able to pull high speed maneuvers that would otherwise be deemed dangerous to try and do in a fw-190??

Structurally, I'd even say the 190 was a bit more rugged, rather than more fragile.

quote:

Isn't it true that p-51s were able to pull high speed maneuvers that would otherwise be deemed dangerous to try and do in a fw-190??

I don't know Bill.

I don't think it is very likely though given the fact both are propeller aircraft with similar airframe limits. I think it comes down to which pilot had more nerve and better feel for their airplane.

High speed maneuvers are deemed dangerous in any airplane. I can definitely see a scared pilot over controlling the airplane and killing himself.

All the best,

Crumpp

quote:

Originally posted by Kettenhunde:

I think you are confused

Yes I am.
On page 4 you said:

quote:

P47, low stiff wing with large aileron surfaces and the weight above the CG centerline in the fuselage lends a destabilizing element which helps to increase agility.

And on page 6 you said:

quote:

We are not talking about weight in relation to the CG, we are talking about the relationship of the NP to the CG.

FC

FC,

It is convenient to think of it as weight as that is how it acts IAW the law of the lever.

On page 4 you got the quick and easy explanation and on page 6 more detail befitting your level of knowledge. Entire textbooks are devoted to this one subject of stability and control.

That is why you were confused by my statement and na85's illustration.

Think of the Neutral point as the fulcrum on a lever. If the CG is directly on top of our fulcrum the lever is neutrally stable and moment is zero.

If our CG is moved to one side then weight X arm = moment about NP

Now turn orientate that lever on the lateral axis and move the CG up. We now have a low wing aircraft and instability or negative stability about the lateral axis. In low wing aircraft it is perfectly acceptable to have neutral or negative stability. The balance of this moment determines our dihedral.

If we move the CG down below the NP, we have positive stability and a high wing aircraft.

Still confused or did that clear it up?

All the best,

Crumpp

Crumpp, I just sent you a PM

I have not recieved a thing. When did you send it?

quote:

If we move the CG down below the NP, we have positive stability and a high wing aircraft.

Just like this FC!

Turn it over and you have a low wing aircraft.



All the best,

Crumpp

quote:

Originally posted by Kettenhunde:

Think of the Neutral point as the fulcrum on a lever. If the CG is directly on top of our fulcrum the lever is neutrally stable and moment is zero.

If our CG is moved to one side then weight X arm = moment about NP

Aircraft is supposed to roll about roll axis which goes through CG. How can NP be a fulcrum than?

BTW check picture of P-47, not exactly a low wing plane I don't expect its CG higher than NP than in other planes.

quote:

Originally posted by Kettenhunde:

quote:

If we move the CG down below the NP, we have positive stability and a high wing aircraft.

Just like this FC!

Turn it over and you have a low wing aircraft.



All the best,

Crumpp

what about "mid-wing aircraft"?

quote:

Originally posted by Kettenhunde:

quote:

Im glad you mentioned this.

It makes a difference to the utility of the trait.

Keep in mind that the aileron design of the FW190 has a wide variation of performance.

It goes back to the point Bremspropeller made earlier:

quote:

To put it differently:
It had the best roll-rate of all fighters in a speed-range at which 95% of all engagements took place.

The helix angles of the P51 and FW190 control systems match at about 340IAS which means that given rigging variations I am sure that some P51's were more agile than some FW190's at high velocity in the sustainable envelope.

There is a very tiny 4% difference in helix angle between the FW-190 and clipped wing Spitfire. Given the variation in rigging we can say too that some clipped wing Spitfires were equally as agile at low speeds and some were not.

Keep in mind the effect on helix angle for the hinging changes in the P47 series. Like all aircraft, the FW190 was improved and had the hinge point moved three times along with design changes.

You cannot make a blanket statement of absolutes on the information given in the report.

As a general performance trend, Bremspropellers statement holds true.

All the best,

Crumpp

Amazing how Crumpp can quote from this report to support one point, then turn around and suggest the material doesn't apply on another occasion.

No facts, no tests, no data, just a broad claim, which is clearly unsustainable.

Crumpp: Please provide test data which disputes the material shown in the report or admit you are making your claims without substantive backing.

The implication that not all Spitfires/P-51's/P-47's might have the same performance as seen in these tests applies equally or more so to 190's. In fact, due to the poor manufacturing standards seen in the 3rd Reich as a result of the nessesity to disperse production, poor transportation links leading to parts not arriving, lack of fuel to fully run in engines and test aircraft, the use of slave labour, (who routinely engaged in sabotage) the typical Luftwaffe aircraft was far more likely to under-perform than the typical Allied.

The 95% claim just doesn't hold up.

quote:

The implication that not all Spitfires/P-51's/P-47's might have the same performance as seen in these tests applies equally or more so to 190's. In fact, due to the poor manufacturing standards seen in the 3rd Reich as a result of the nessesity to disperse production, poor transportation links leading to parts not arriving, lack of fuel to fully run in engines and test aircraft, the use of slave labour, (who routinely engaged in sabotage) the typical Luftwaffe aircraft was far more likely to under-perform than the typical Allied.

Tell me which impact all of that has on an aircraft's roll-rate

There had been an issue with Ago-built airlerons.
The problem was fixed by mating Ago ailerons and Ago wings only.
Easy fix, wouldn't you agree?

Please spare people from your stupid agenda of german aircraft being worth less than the dirt underneath someone's fingernails.

The 190 outrolled every single allied fighter at the crucial speeds.
Fact.

No need to find excuses or accusing ppl of lying and twisting stuff.

@ Crumpp:

Just re-sent it as new a topic - you should get a notification now...

(EDIT)
I just wanted to share this one:

This message has been edited. Last edited by: Bremspropeller,

Lovely pic, Brems.

Given that the FW 190A had everyone on the Allied side convinced that it was a better turner than the Bf 109 (apparently on the assumption that 'manuverability' is defined by turning circle), its roll had to be pretty good, and the pilots who flew it learned quickly how to exploit its virtues.

As for Bob Johnson's belief that he could outroll anything in a P-47, I think that there were three factors at work there:

1. The P-47 had a better roll response than most of its Allied contemporaries. The clipped wing Spits don't appear to have been as prevalent as maybe they should have been along the Channel Front.

2. Johnson was an exceptional pilot who could wring every last bit of goodness out of his aircraft, and his maintenance team reputedly gave his aircraft a little extra goodness compared to the norm.

3. A roll experienced seems a lot faster than a roll observed, at least judging by my limited time in the air.

cheers

horseback

agreed.



I think pilot strength and aileron leverage would determine the roll rate performance at higher speeds.

quote:

Originally posted by horseback:
Given that the FW 190A had everyone on the Allied side convinced that it was a better turner than the Bf 109 (apparently on the assumption that 'manuverability' is defined by turning circle), its roll had to be pretty good, and the pilots who flew it learned quickly how to exploit its virtues.

As for Bob Johnson's belief that he could outroll anything in a P-47, I think that there were three factors at work there:

1. The P-47 had a better roll response than most of its Allied contemporaries. The clipped wing Spits don't appear to have been as prevalent as maybe they should have been along the Channel Front.

2. Johnson was an exceptional pilot who could wring every last bit of goodness out of his aircraft, and his maintenance team reputedly gave his aircraft a little extra goodness compared to the norm.

3. A roll experienced seems a lot faster than a roll observed, at least judging by my limited time in the air.

cheers

horseback

+1

quote:

Originally posted by Kurfurst__:
Lovely pic, Brems.

+1