# Questions tagged [performance-calculation]

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

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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 \...
1 vote
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### 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
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?
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 ...
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?
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 ...
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 ...