Author Topic: Question about flight model.  (Read 301 times)

Offline Zigrat

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Question about flight model.
« on: September 19, 2000, 10:14:00 PM »
OK I *think* I know the answer to this but before i go spouting off i figure I would ask.

The minimum drag on a airplane in 1 g flight occurs at what is known as the "best climb" speed in here, since that is where the most excess power is available for climb (it is the point of minimum combined induced,skin friction,form, and wave drag).

Sooo, if you go level flight, reduce power setings to where you are only maintaining that speed (the best climb speed) if power is cut any more, it should not be possible to maintain that altitude, even if you are well over stall speed right? Since as speed decreases, your drag increases (because of the larger induced drag dominating the relative small skin friction and form drag)and your plane should drop.

Is that right? Im 99% sure it is. Question, is is that how it happens in AH? Might be my computer is defragging so i can't test it  


Offline Pyro

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Question about flight model.
« Reply #1 on: September 19, 2000, 10:21:00 PM »
Close.  Best climb is not necessarily at minimum drag because available thrust horsepower varies with speed.  Best climb will be where thp available - thp required is greatest.  



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Offline Udie

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Question about flight model.
« Reply #2 on: September 19, 2000, 10:25:00 PM »
Thnx for taking care of that one Pyro, I was worried I was going to have to dazzle Zigrat with my vast ammount of knowledge on arrowdinamicks.  

Udie

[This message has been edited by Udie (edited 09-19-2000).]

Offline wells

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Question about flight model.
« Reply #3 on: September 19, 2000, 10:26:00 PM »
Very close

Best climb speed is a tad faster than the speed for lowest drag, since climb rate is not only a funtion of excess power, but also speed.  At some speed, excess power starts to drop, but if the speed increase is greater than the drop in excess power, climb rate will continue to increase, make sense?

Best glide speed would be the speed of lowest drag, probably about 20 mph slower than best climb speed, but otherwise, yeah, you nailed it!  

Offline Zigrat

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Question about flight model.
« Reply #4 on: September 19, 2000, 10:32:00 PM »
Thanks pyro  
I undderstand alot about the FM but propellar effeciency has been something that has always eluded me soince in college they dont teach about piston powered aircraft anymore (!) and focus solely on the various forms of  brayton cycle and rocket propulsion  

Offline easymo

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Question about flight model.
« Reply #5 on: September 19, 2000, 11:38:00 PM »
 You can set the auto climb for 100 in a number of planes now. Includeing the F4U(it buzz,s but keeps climbing) Strangely, the G10 (best climber in the game) has trouble with this.  I thought some one said there would be no change to climb. You couldnt do this in any plane in 1.03. None of this FM makes much sense to me.