Luftwaffe and Allied Air Forces Discussion Forum - Performance of the Fw 190A on the Deck?

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- - Performance of the Fw 190A on the Deck? (http://forum.12oclockhigh.net/showthread.php?t=13886)

Re: Performance of the Fw 190A on the Deck?

Quote:

Originally Posted by Crumpp (Post 70978)

I calculated the affect of weight on the aircraft. That affect does not change simply because the aircraft no longer has the ability to compensate for it.

You calculated weight related calculation but it had very little to do with question in hand, nor with the scale of the speed reduction due to fuel state.

Quote:

Originally Posted by Crumpp (Post 70978)

So we can see that both calculations methods give the same result for that specific problem.

This was originally written by me when I pointed out that my method can give same result as yours, when calculating the speed increase needed to maintain constant Cl at higher weight. But let's quote my next sentence (post #150 of this thread) which you leaved away:

"However, the result for this specific problem, the speed change required for constant Cl at higher weight, is over ten times higher than the result for the problem in our hand."

In other words, you try to use my words so, that the meaning is exactly opposite than in the original text. This is just one example how you have been twisting my words last 14 pages.

Re: Performance of the Fw 190A on the Deck?

No one has twisted your words, Harri.

Quote:

Harri Pihl says:

Quote:

"However, the result for this specific problem, the speed change required for constant Cl at higher weight, is over ten times higher than the result for the problem in our hand."

You lose the forest for the trees as all you can see is your one specific solution you have been taught to parrot. You don't seem to understand that the force of weight continues to have the same affect on the aircraft whether it is at high velocity or low velocity.

If we increase the weight, our aircraft needs to overcome it to maintain performance.

I don't know how else to tell you that much clearer. Any lower level aerodynamics course will tell you exactly the same thing and to prove that you can easily perform a parametric study on your own.

Try thinking really hard on this part, Harri:

Quote:

Certainly! Why is that change so small? What the differences?

Because the aircraft does not have the Power available to meet the new power required! The Angle of attack must increase and the velocity slow down.

Of course in a propeller aircraft as our velocity decreases we know our thrust increases!

The affect of weight is very much present and the aircraft's entire envelope is still reduced

There is change in the aircraft's ability to compensate for that affect but the affect of weight is exactly the same.

No change in the significance of weight.

That is evidenced by your own calculations:

Quote:

The lift coefficient at 9680lbs (4390,85kg) and 352mph (566,37km/h=157,324 m/s) at sea level is, as allready demonstrated:

Quote:

Speed V =157,324m/s
density r = 1,225kg/m3
wing area A = 21,83m2
Lift L = 4390,85*9,81 = 43059,51 N

Cl = L / (A * 0,5 * r * V^2) = 0,13011

At 10280lbs required lift is:

L = 4663,01*9,81 = 45728,487 N

So we can solve the required speed at constant Cl at higher weight using these:

V = SQRT( L / (A * 0,5 * r * Cl)) = 162,17m/s = 583,66 km/h

And we can check this with your formula as well:

V2/V1 = SQRT(W2/W1)

583,66km/h/566,37km/h = SQRT(4663,01kg/ 4390,85kg)

1,031 = 1,031

So we can see that both calculations methods give the same result for that specific problem.

So when we isolate the affects of weights in a parametric study to see the true affect, we can only conclude that weight has very significant affects upon an aircraft, even at high speeds.

All the best,

Crumpp

Re: Performance of the Fw 190A on the Deck?

Quote:

Originally Posted by Crumpp (Post 70995)

This is actually your problem here; you use the formula which wrongly assumes constant Cl/Cd relation for the question in hand. My solution correctly changes the Cl/Cd relation to reach new balance between the drag and thrust. Thus, the effect is not the same nor the results comparable.

This is the principal difference between these approaches and allready pointed out in the posts #21, #24... and also #150 of this thread, which you continously misquote and try use to for exactly opposite purpose, it was originally posted.

But as allready seen in this thread, there is no limit how far you will go on this. In the AH board you were banned for this kind of manners and I've been told that the same happened in the ww2aircraft.net, where I have never posted.

Re: Performance of the Fw 190A on the Deck?

Although this is an interesting thread, it has not really been a constructive discussion for some time now.

I'm closing the thread, since the original topic has been largely overshadowed by a mathematical argument.

But I would like to add that it was refreshing to step away from the beaten path.