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Questions tagged [performance-calculation]

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

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93 views

How to calculate service ceiling and absolute ceiling in PA-44 Seminole?

I am hard to understand to calculate service ceiling and absolute ceiling in PA-44 Seminole. Is there anyone know how to calculate it in the condition(T/O weight: 3599.24 L/D weight: 3354.44 PA:2329 ...
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2answers
111 views

What margin of error should one reasonably allow regarding aircraft performance?

This question generated a lot of discussion around amateur pilots often making the mistake of calculating aircraft performance based on perfect conditions and not allowing for a 'safety factor' (i.e. ...
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2answers
90 views

How can I correct an expected climb rate for density altitude?

If a flight manual (for a naturally aspirated piston engine plane) gives a figure for a best climb rate at standard temperature and pressure, is there a way to adjust that figure for a different ...
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2answers
66 views

Is the route which takes the least time always the one with least fuel-burn?

Geographically longer paths may require less fuel than the shortest (great circle) path. But what about time ? Is the most fuel efficient route always the one that has the aircraft in the air for ...
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4answers
249 views

Can longer paths consume less fuel than the (shorter) great circle path?

Is the most fuel-efficient route between points A and B always along a great circle ? Although somewhat counter-intuitive, this comment on an aviation blog seems to suggest that longer paths (in ...
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0answers
146 views

How are the takeoff V speeds calculated? [duplicate]

What is the actual formula for calculating the takeoff V speeds of an aircraft with any configuration? Specifically, I mean V1, Vr and V2 I know there are many factors, but what are they specifically ...
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1answer
113 views

What are the takeoff and landing distances of motor gliders?

I'm doing some estimations of weight and thrust loading for a college project, and in the formula below the landing distance is not a variable, but should be estimated using similar aircraft and usual ...
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7answers
574 views

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 ...
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2answers
976 views

How can I calculate takeoff distance in a generic way?

I want to build a generic performance app. For many of the aircraft the only available method is using the takeoff charts manually (I'm not referring to the more simple-to-calc short field charts but ...
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2answers
136 views

How can I calculate a pitch/power table?

I want to make a pitch and power table for C172s based on calculation, just like I attached above. I picked up this table on internet, but I'm not sure where it comes from. Do you have any ideas how ...
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1answer
136 views

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 ...
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1answer
140 views

Where can I find climb and cruise performance charts for a specific aircraft?

I'm looking for climb and cruise charts for a cirrus sr20 G3, but I can't find them in the POH? where are these charts typically located?
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1answer
152 views

How to compare turboprop engines and with which values?

I have found this website that lists a lot of turboprop engines. I would like to compare them with as few values as possible. As an example, there are tons of different values that describe a jet ...
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2answers
100 views

How do I calculate FPNM for standard take-off minimums?

I have trouble understanding and calculating FPNM for standard take-off minimums. As I understand, the formula is: (Ground speed)/60 * FPNM = FPM Let's say the ODP says: 565' per NM to 2800, or ...
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1answer
425 views

How do I determine the engine thrust required to give a specific climb rate?

New pilot here and I am playing around with a flight simulator game for the B737-800. I need some help understanding where/how one can find out if one has enough engine thrust (%N1) to meet a required ...
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2answers
207 views

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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1answer
236 views

What are the Boeing 777 thrust calculations? [closed]

Can someone show typical calculations for a Boeing 777 jet engine for the following criteria: Take off thrust of the engine at 170 mph take off speed and 45 degrees F Cruising thrust required at 500 ...
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2answers
101 views

How can I determine specific heats of gases for turbojet engine calculations?

I'm in a combustion lab and we are performing experiments on a turbojet engine. However, I am having some trouble calculating the exit velocity and compressor/turbine powers of the engine. Consider ...
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1answer
154 views

Why are the positive points in a V-n diagram associated with pitch maneuvers?

For an aircraft with such flight envelope, the flight conditions in point A, C and D are ...
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1answer
698 views

How to calculate the Gust Envelope?

I am trying to draw the V-n Diagram for a small aircraft I built, but I am stuck in the gust envelope part. I know how it is supposed to look. However, I am having a hard time calculating it. I would ...
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2answers
213 views

Why do some multi-engine aircraft have accelerate-go distance in their performance charts and some don’t?

I'm curious about why some airplanes have accelerate-stop distance (ASD) and accelerate-go distance (AGD) in their performance charts and some don’t include that. Does anyone know why?
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1answer
1k views

Calculating Ground Speed - E6B vs Pythagorean Theorem

I have been trying to create an excel formula for calculating the ground speed of an airplane using the TAS, Course, Wind Dir, and Wind Velocity. The issue that I am finding is that I can't properly ...
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0answers
139 views

How can I calculate different airspeeds given atmospheric data?

I want to calculate various airspeeds (TAS,CAS,IAS,..) given a certain altitude. With the given altitude I can figure out the pressure, density, speed of sound, temperature, and viscosity. However, I'...
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2answers
832 views

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 ...
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0answers
104 views

How are the landing, takeoff, and cruise speeds calculated for my homebuilt ultralight?

How can I calculate the takeoff, landing, and cruise speeds of my ultralight with a total weight (with load) of 120 kg, average air density of 1.23 kg/m3, wing area of 13.18 m2, and a coefficient of ...
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1answer
2k views

How to calculate required thrust for take-off knowing gross weight and L/D?

I know that many variables play into the required thrust for a take-off and for climb. Most of those specs boil down to a targeted gross weight, wing loading and L/D ratio. Intended flying speed range ...
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2answers
4k views

How do we calculate top of descent (TOD) in flight? [duplicate]

What is the in-flight trick? I know how to calculate it in theory, but how can I calculate it fast? For example, I know I can use this formula for calculating the rate of descent: [ground speed + ...
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4answers
175 views

What experimental techniques should one employ during cruise flight to determine correct airspeed to fly for max range in a headwind or tailwind?

Theory demonstrates that one ought to increase speed in an headwind, and decrease speed in a tailwind to achieve maximum range. A lengthy discussion on the theoretical solution was answered, though ...
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3answers
522 views

How to perform a “first principle” performance calculation?

I am a PhD student on flight dynamics and control. This week I was given an assignment to do some research on methods of aircraft performance calculation. After some search on the Internet, I found ...
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2answers
2k views

How to ballpark IAS vs TAS?

Is there some reasonably accurate ballparking formula to allow for quick conversions between IAS and TAS as a function of pressure altitude and difference of ground temperature relative to standard ...
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1answer
126 views

How should I interpret the Douglas DC-4 approach climb performance chart?

Can someone explain what "C = .04 Vso2" means as the "denotes required rate of climb?". I assumed the point at 6500 ft altitude and 60,000lbs landing weight will mean that the required rate of climb ...
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3answers
895 views

Does the dew point affect density altitude?

I am looking for the most accurate formula to calculate the Density Altitude (DA) to use it for calculating aircraft performances during landing. Now I found the following formula: DA=PA+[120*(OAT-...
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1answer
218 views

Why do DC-4 landing performance charts have different values for the intended and alternate destinations?

I am studying the landing performances of the old Douglas DC-4 and there are a lot of different landing performance charts available. The pilots can use different flap settings during landing like 45, ...
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2answers
1k views

What is the formula for estimating the maximum stationary thrust of a rotor as function of its diameter?

I am new! New to this forum and new to aviation (i normally deal with statics) so thanks in advance for beeing patient with me. Recently i was trying to figure out how much weight a rotor can lift as ...
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1answer
685 views

How to calculate the DC-4 landing distance with this graph?

Can someone give me a clear explanation on how to calculate the landing distance of the Douglas DC-4 with the following graph? And why is the Temperature variable not in the graph, because temperature ...
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1answer
317 views

What's exactly meant by the “slippery when wet” report on ATIS?

I read this discussion and discovered the definition of "slippery when wet" from this advisory circular but I'm still having a hard time understanding why the runway condition is expressed as "...
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1answer
647 views

Why does lower atmospheric pressure produce higher EPR (thrust)?

Recently, I read manual about engine, PW JT8D-217A/C, and there is a chart making me so confused. Manual show the reference table tells you what number, EPR, is normal in specific temperature and ...
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1answer
4k views

Is there a specific formula or way to calculate flex temperature for an Airbus A320?

I have hear of RTOW charts but I haven't seen any calculations with the runway length or slope. What is the formula or equation to finding flex temperature and V-Speeds?
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1answer
158 views

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 ...
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2answers
800 views

What makes V1 one or two knots less than Vr on this performance table?

(B738 AFM, 0-2000 feet elevation, up to 27°C) Example of V1 and Vr differences. The table shows that the V1 speeds are invariably one or two knots lower than their matching Vr speeds. Given that V1 ...
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1answer
358 views

Is reducing V1 a viable option for pilots when the ASDA is shorter than the ASDR?

Let's say you were planning to ferry some passengers and cargo in a jet but after some calculations found out the ASDR (Accelerate-Stop Distance Required) was greater than ASDA (Accelerate-Stop ...
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2answers
870 views

How does the FOVE system work with the Airbus FMS?

The Flight Operations Versatile Environment (FOVE) is a separate software system used with Airbus aircraft by dispatchers to determine performance data to enter into the FMS. There seems to be little ...
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0answers
226 views

What calculations are needed for counter-weight balancing on a propeller?

I am designing a small-scale propeller and i have managed to design on optimized geometry for the blade. However the blade pitch angle adjusts according to different flow speeds so i need to mount ...
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1answer
3k views

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 $c_{D0}$?
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1answer
365 views

How to calculate the performance parameters of an hexacopter (UAV)? [closed]

I need to calculate the performance parameters like cruise speed, endurance, range of my hexacopter but how can I do that! Also, is there a way to obtain motor-propeller performance parameters ...
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1answer
2k views

What are fuel biases?

Does anyone have an idea of what is it? From what I gathered from the web, it seems that this is the margin of error between the actual, real fuel consumption of the aircraft and the fuel consumption ...
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2answers
5k views

Is there a formula to calculate ground distance traveled given rate of climb and true airspeed?

I'm looking for a formula to calculate the horizontal distance (guess it is the Ground Distance) passed during the phase of ascent (or descent), having the rate of climb in ft/min and the TAS in knots....
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2answers
2k views

How does blade solidity ratio relate to thrust/power/torque of a propeller?

for quite some time I was using ABBOTT formula for static thrust estimation on a two-bladed propellers: $$ T=6.8\times10^{-5}\times D^{3}\times p\times RPM^{2} $$ $T$ is Static Thrust (N); $D$ is ...
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1answer
418 views

Is there a difference in aerodynamic efficiency between single engine and twin engine airplanes?

I've learned a lot of great information about aviation on this website. One insight I learned from a poster here is that, all else equal, for every doubling of engine power that you give an airplane, ...
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4answers
1k views

How do you calculate trip fuel based on hourly fuel burn rates?

I am working on a small personal project that uses fuel burn data about specific aircraft to calculate the total fuel required for a trip. The data looks like this: ...