La7 speed at 13k is 10mph too fast

[hitech]

HoHun, I understood your post perfectly. The resone I said a thick/high lift wing is because with a high lift wing, the zero lift aoa is in the large - direction, hence getting into the steaper part of a normal profile drag curves, hence the profile drage would change more with a small aoa change than the induced drag would.

I agree it can theoreticly be the case, just doubt if it is the norm, you could also make a configuration where adding the first 1000 lb increased speed the next 1000lb slowed it down.

White Hawk , the only resone weight will effect top speed either increase or decrease is do to a change in drag.  The over all e state i.e. (v^2  + Alt) * mass would most likly be higher for a heavier plane in level flight at a given altitude.

[WhiteHawk]

True, true.  The increase drag (frction) due to the increase in the Angle of attack of the aircraft necesary to maintain the the alt.      
  Prolly one dozen of one and a half of the other, but, if the
angle of attack were fixed as wel as the alt and the thrust,  and the weithgt were added in such a way that drag profile was
not changed, (internally), I would say the plane would slow,
in accordance w the E equation.  (increasing M would
reduce V for all values M>0 until V=0).
  But since I didnt have the E equation proior to this debate
NOR did expect anybody else to have it, I can only say that
this is my humble, yet correct, opinion    

[WhiteHawk]

So tyhe cute faces change to cute faces AFTER the reply is
submitted.  AHAAAAAA!

[HoHun]

Hi Hitech,

>I agree it can theoreticly be the case, just doubt if it is the norm, [...]

I'd expect it to be the norm: If the angle of incidence is selected for full pressure altitude at design weight, the aircraft will have a nose down attitude at all lower altitudes for the same weight.

As many later fighter versions received more powerful engines without angle of incidence being changed, too, this effect probably was even more pronounced with the late-war fighters.

>[...] you could also make a configuration where adding the first 1000 lb increased speed the next 1000lb slowed it down.

Exactly, there's actually an optimum weight for each altitude (below design altitude), higher than the design weight.

Regards,

Henning (HoHun)

[Charon]

Wow, I'm always learning something new here. I almost wish I were a little better at all that math stuff

Charon