[Crumpp]

Now we are getting somewhere!

Speed change due to weight change if power is constant and the other parameters are adjusted accordingly as demonstrated earlier is:

delta V = -1,48 km/h

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.


So this result:

Speed change due to weight change if power is constant and the other parameters are adjusted accordingly as demonstrated earlier is:

delta V = -1,48 km/h

Is really exactly the same as this result:

while the speed change to keep Cl constant when the weight change is:

delta V = +17,3 km/h

As demonstrated by your first set of calculations:

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