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Questions tagged [performance-calculation]

Questions about calculating the various measures of performance of an aircraft.

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7 votes
1 answer
516 views

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 \...
1 vote
1 answer
9k views

How do you calculate indicated airspeed on a flight plan?

I'm planning my cross country journey for my flight test and it seems I forgot how to calculate my indicated airspeed. The indicated airspeed must be from the POH, right? The the true airspeed is ...
1 vote
2 answers
5k views

Is trigonometry used by commercial pilots?

Do pilots (for example commercial pilots) need to use trigonometry (directly, with trigonometry knowledge) as part of their routine job? If so, when is it most used and for what?
4 votes
1 answer
582 views

Why do you need to subtract when using a climb/descent performance chart for an altitude other than sea level?

If you look at this chart you see we subtract 3 minus 1, 9 minus 2, and 30 minus 4 in the example calculation. My question is, why do we subtract these numbers? Do we subtract the same numbers each ...
6 votes
1 answer
955 views

Why is this chart called a Short Field Effort Takeoff Ground Roll and not simply a Short Field Takeoff Ground Roll?

What does the word 'effort' mean in this context?
2 votes
1 answer
196 views

Is it common to change the type of engine during major overhauls?

Is it common to change out the type of engine during major overhauls of old aircraft? For example, replacing a 285 hp engine with a 310 hp. Would this invalidate the performance specifications found ...
8 votes
1 answer
6k views

What are the meanings of various reference lines and sections in a take-off distance graph?

I am trying to solve a numerical problem related to determining take-off roll using a take-off distance graph. The parameters are Temp: 90F, Press. alt: 2000ft, wt: 2500lbs, headwind: 20 Knots. I got ...
5 votes
1 answer
715 views

Is there an equation which allow us to perfectly match a helix propeller and an engine?

Is there an equation which allow us to perfectly match a helix propeller and an engine? I'm looking for an equation that allow me to correctly dimension an helix propeller for my engine. I mean that ...
7 votes
1 answer
38k views

What would be the ground roll and total distance to clear a 50ft obstacle given these conditions?

I'm a student pilot, the question I am trying to answer is What would be the ground roll and total distance to clear a 50ft obstacle given an elevation of 5,000ft, altimeter 29.52, and a ...

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