All Questions
Tagged with performance-calculation aerodynamics
13 questions
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365
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For a fixed density altitude, how does climb performance depend on pressure altitude?
Below is the climb performance from the 1978 Cessna 152 POH, which I've plotted as climb rate versus density altitude. It shows that higher pressure altitude gives decreased performance even when the ...
CommunityBot
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2
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I don't quite understand the derivative in this vertical wind gust formula
First my english writing skill is still bad so pardon me if i accidentally made any mistake TT-TT.
So recently I have learnt about how the vertical gust affect the load factor and the calculation ...
- 237k
1
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3
answers
2k
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Propeller Characteristics at Different Altitudes
Assuming I have a propeller with a given diameter (D), pitch, blade twist, and number of blades, I can theoretically analyze discrete airfoil sections in XFOIL and come up with lift and drag polars ...
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1
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How to calculate boundary layer thickness?
So I have a flat plate with a surface of 7sqm and an aspect ratio of 12 with air blowing straight at it (like a wing) at a speed of 50km/h. I would like to manually calculate the thickness of the ...
- 16.5k
9
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2
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Why do helicopter performance charts for hover out of ground effect (HOGE) have a "knee"?
Have a look at the following performance charts from Section 5 of Robinson R-22 Pilots Operating Handbook for hover out of ground effect (HOGE). If the temperature and gross weight are known, the ...
- 21.3k
5
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9
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How does maximum speed vary with altitude?
Question: How does a commercial jetliner's highest possible groundspeed vary with altitude (assuming wind=0) ?
My understanding is that drag decreases with altitude, therefore maxspeed increases with ...
- 2,117
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2
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How to calculate the induced drag coefficient?
In an exercice of Flight mechanic, I have to compute the drag coefficient at zero lift: $C_{D0}$.We saw in class two ways to find it :
$$
C_{D0} = \frac{\pi AR e}{4E_{max}^2}
$$
With $AR$ the aspect ...
- 435
3
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1
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What methods are used for calculating maximum takeoff windspeed of a helicopter?
I would like to calculate the maximum windspeed in which a helicopter may safely take off and safely land, assuming a theoretical wind environment with constant wind direction and no gusts.
I ...
- 4,877
1
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1
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How do you calculate Profile Drag?
second year aeronautical engineering student here. I'm doing some aerodynamics coursework but have run into a problem.
I've read through the answers to the question "what is profile drag?" but ...
- 32.7k
3
votes
2
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5k
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How to realistically model propeller static thrust?
I am graphing static thrust vs prop diameter for a 600 kW motor and a prop diameter up to 5 m. I have seen the post 'What is the equation for calculating static thrust?' and using its formula and ...
- 21k
4
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1
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Is it possible to determine a rotation speed (Vr) using other known V-Speeds?
Is it possible to come up with a good estimate of rotation speed using other known V-Speeds?
For example: if I know a plane has a Vs @ 55kt. and a ...
CommunityBot
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6
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1
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How is the zero-lift drag coefficient calculated?
The drag coefficient is usually given as a funtion of the lift coefficient and the zero-lift drag coefficient ($c_{D0}$):
$c_D=c_{D0}+k\cdot c_L^2$
How can I calculate/estimate $c_{D0}$?
- 62.9k
7
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1
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For jets, how can we show that 1/2*ρ*V^2 is equivalent to 1481.3*δ*M^2?
In Roskam's book, we find the following relationship given for climb performance in jet aircraft:
Thrust requested = $D$ = $C_d \cdot (1/2 \cdot \rho \cdot V^2) \cdot S = C_d \cdot (1481.3 \cdot \...
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