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Questions tagged [performance-calculation]

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

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1 vote
1 answer
344 views

Can this plane make it to an airport after dual engine failure?

If you are flying to the most remote airport(according to simple flying most remote airport is Mataveri International Airport), while flying on a typical airliner with normal weather, in the event of ...
1 vote
3 answers
358 views

What is the mathematical relationship between mass and speed for constant thrust in level fight?

Imagine that we have a wing with constant thrust in level flight. Then imagine that we add mass to that wing. In order to maintain level flight, I would expect that the angle of attack would need to ...
2 votes
1 answer
238 views

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 ...
7 votes
2 answers
1k views

How can I calculate the C.G height for an Aircraft?

before I continue I would like to thank you guys beforehand for the help. I am new to this forum and in aviation in general. I am helping my professor to obtain the C.G coordinates in x, y , z for a ...
1 vote
1 answer
100 views

Determining Required Fuel from Payload/Range Diagram

I would like to determine the amount of fuel required for a flight at a given range/payload combination - ideally from the payload/range-diagram [1] of the corresponding aircraft alone. I know that ...
0 votes
2 answers
185 views

Why is higher V1 preferred over lower V1 in takeoff performance calculations?

I am using a takeoff performance application that seems to prioritize a higher V1 speed whenever there is extra runway available. It does this as long as the Acceleration-Stop Distance (ASD) remains ...
0 votes
1 answer
1k views

Confused about screen height definition

I’m a bit confused about screen height definition and I’m seeking help to understand it. I understand that this height for landings is at least 50 ft above the landing threshold for all airplane ...
0 votes
0 answers
34 views

What are the parameters typically used by airlines to assess the fuel economy and efficiency for their flights?

Are there parameters that are typically being used by airlines to assess the fuel economy and efficiency done in their flights? And how exactly those parameters are being used to do the assessments ...
0 votes
0 answers
115 views

How do you calculate the theoretical vertical speed of an aircraft? [duplicate]

I'm doing this for a High School research paper, so it would be preferable if little calculus is used for any calculations (up to Calculus I is probably okay). This should be based off of the flight ...
4 votes
2 answers
803 views

What are the standard numbers for fuel consumption (kg), kg/NM, and kg/h, of Boeing 737-300?

I'm currently working on a school project regarding the analysis of Boeing 737-300 fuel consumption. I'm working on some parameters that my supervisor gave me, which are : Total fuel consumption (kg),...
1 vote
3 answers
2k 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 ...
2 votes
1 answer
77 views

Material Shape Parameter (n)

In order to calculate the plasticity reduction factor given in Michael C.Y. Niu's book a constant (n) is being multiplied which is called the material shape parameter, does anyone know the meaning of ...
0 votes
2 answers
99 views

Are UDF/Propfan Engines Thrust Producing or Power Producing? [duplicate]

For the purposes of aircraft performance (best endurance/range speeds, Vx, Vy, etc.) would a propfan be considered a power producing engine or a thrust producing engine? I would imagine it would be ...
0 votes
2 answers
163 views

Why do I keep getting different results to an aircraft's turn radius when I plug variables into different calculators and solve on my own?

I'm trying to solve for an aircraft's turn radius at mach 3.17 (2432 mph) and a bank angle of 19.8; however, after using various online calculators and personally solving the equation, I keep getting ...
0 votes
0 answers
95 views

Is there an equation to solve for bank angle using load factor and wing loading as variables? If so, what is it?

The problem is that I'm looking for both wing loading and load factor as variables to solve for bank angle and cannot find any equation that represents this. After searching various websites and not ...
0 votes
3 answers
18k 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 ...
1 vote
1 answer
303 views

Question about V1 Vr V2 computations

On ASA’s ATP test book they mention the following: “V1 is computed using the actual airplane gross weight, flap setting, pressure altitude and temperature.” I understand that v1 gets adjusted for ...
1 vote
0 answers
301 views

Dispatch Landing vs. Inflight Landing Performance Calculation

What is the difference between Dispatch Landing and Inflight Landing Performance Calculations? Are you obliged to use both? Specifically concerned with EASA rules.
2 votes
2 answers
3k views

How would I calculate CG in this practice problem?

As I'm studying PPL theories, I've encountered with this kind of a question below and it would be great to understand the principle behind the calculation of the 'CG' Calculated take-off mass = 2300 ...
4 votes
2 answers
3k views

Help me understand the A220-100 takeoff chart

Here is the takeoff performance chart of the Airbus A220 (CS100). According to Wikipedia, the MTOW runway length needed is 1500 metres. However, this chart seems to suggest that a runway length of ...
1 vote
1 answer
281 views

How would Vy be adjusted for changes in gross weight?

For piston propeller aircraft, Vy calibrated airspeed[CAS] is equal to CAS for best Lift/drag at the plane's absolute ceiling, and at lower altitudes Vy increases above best L/D as excess power is ...
9 votes
1 answer
3k views

How does a fighter pilot calculate approach/landing speeds?

Let's say an F/A-18C returns to land after expending some payload. Fuel burned and weapons released made the plane lighter. I guess the aircraft computer can tell the pilot the actual weight of the ...
0 votes
1 answer
823 views

takeoff and landing distance GRAPH for a Cessna 150

I cannot find a takeoff and landing distance GRAPH for a Cessna 150. The C172 is easy to come by but why no C150?
2 votes
1 answer
102 views

Is there a simple formula for estimating supercharger throttling losses?

I’ve noticed that in both Aerodynamics for Naval Aviators, and most old WWII engine power charts, power vs altitude seems to be composed almost entirely of linear relationships: at a given ...
1 vote
1 answer
585 views

what is ''extended runway centerline''?

When we calculate performance with fly smart,we see:‘‘Take off based on climbing on extended runway centerline‘‘. What is the meaning of‘‘extended runway centerline‘‘?How long is Extended?
1 vote
2 answers
148 views

Why does the airplane manual state S1 is equal to or greater than the higher of ground minimum control speed or critical engine failure speed

I don't understand why S1 is equal to or greater than the higher of Ground Minimum Control Speed or Critical Engine Failure Speed (Vcef). I do understand that S1 has to be the lowest of Refusal Speed, ...
0 votes
1 answer
103 views

How to measure fuel level from uneven tank?

If you measure the fuel level with a dipstick on the C172 I fly, you can get two different readings. This is because directly under the filler cap opening there is a cuboid-shaped sensor. Obviously, ...
0 votes
1 answer
182 views

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 ...
4 votes
3 answers
524 views

Is a ducted fan considered a jet or propeller for the performance parameters?

Right now I am working on a UAV design which will use ducted fan. But the performance calculations are a bit troublesome. For some calculations jet and propeller results are almost same but for the ...
0 votes
1 answer
400 views

What is the meaning of "airport pressure altitude" on a flight performance graph?

In a flight performance graph what is the meaning of airport pressure altitude? Is it the top of climb? Because if I set my altimeter to 29.92 it will give me the pressure altitude for an airport at ...
4 votes
1 answer
361 views

Calculating airspeed by flying in a U shape: Horseshoe Heading Technique

I saw some equation in a log recently and I believe it went something as follows: $v_1$ : flying North, $\ \ v_2$ : flying West, $\ \ v_3$ : flying South. $$ \text{TAS} = \frac 1 2 \sqrt{v_1^2+v_2^2+...
1 vote
1 answer
834 views

Calculating center of gravity when calculated CoG, T/O mass, fuel burn and fuel burn station are known

I'm practicing for my EASA PPL(A) exam and one of the questions I came across sound like this: Calculated take-off mass = 1082 kg, calculated CG = 0.254 m, fuel burn = 55 l on station 0.40 m. A. 24.6 ...
11 votes
2 answers
3k views

Why does the takeoff N1 limit start to decrease below 30°C OAT?

It's easy to understand why the takeoff N1 limit decreases with an increase in the OAT in the chart above; the engines get less dense air at higher temperatures, and less dense air means less engine ...
6 votes
1 answer
636 views

How is Fuel needed to be consumed calculated when MTOM and Actual Mass is known

I'm practicing for my EASA PPL(A) exams and one of the questions I came across looks like this: How much taxi fuel must be consumed before take-off to reduce the aircraft mass to the maximum take-off ...
5 votes
5 answers
3k 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: ...
1 vote
1 answer
623 views

How to calculate the climb performance of an A320

Recently I have been taking off in Innsbruck (LOWI) with my A320 (in Microsoft Flight Simulator, because I cannot afford the real one) and quickly found myself greeted by a GPWS Warning: "Terrain ...
9 votes
2 answers
1k views

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 ...
9 votes
6 answers
5k views

Does an increase in air temperature actually improve aircraft performance?

Mainly because of what pilots learn about density altitude and aircraft performance, any idea that an increase in temperature could improve performance seems counterintuitive. And indeed it is. Here's ...
2 votes
4 answers
2k 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 ...
12 votes
4 answers
15k views

How can true altitude be calculated from pressure altitude, temperature and altimeter setting?

The manual that came with my Jeppensen E6B has the following sample... If an aircraft is flying at 12,500 feet with an outside air temperature of -20C and the altimeter is set on 30.42 inches of ...
6 votes
2 answers
29k views

What formula to use for calculating pressure altitude?

I'm having some trouble making my calculations of pressure altitude match those in apps and text books. I'm using the formula from Wikipedia: (29.92 - altimeter setting) * 1000 + airport elevation ...
1 vote
0 answers
129 views

Why does V2 decrease for intersection takeoff

I have noticed that the VR and V2 decreases for same FLEX when departing from an intersection runway even when sufficient stop margin is available. What is the reason for this? And also does EFB ...
3 votes
1 answer
162 views

How useful were the wings and tail of Jean-Pierre Blanchard's balloon?

In 1784, Jean-Pierre Blanchard fitted a hand-powered propeller to a balloon, the first recorded means of propulsion carried aloft. In 1785, he crossed the English Channel in a balloon equipped with ...
5 votes
9 answers
14k 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 ...
6 votes
4 answers
18k views

What is the maths behind the descent rate calculation?

The descent rate calculation states that descent rate is calculated by 'groundspeed / 2 * 10'. Another document stated that the ground speed should be multiplied by 5 (or more accurately 5.2) to ...
1 vote
2 answers
2k 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 ...
0 votes
0 answers
101 views

Are there significant differences between EASA and FAA when teaching jet aircraft performance?

Both regulatory bodies did a great effort in regulation harmonization, but I'm looking for any significant differences (if any) in how is taught the subject from the pilot point of view, i.e. ...
3 votes
3 answers
288 views

Do pilots of piston/prop aircraft have discretion to determine how much runway is required for an intersection departure?

For piston/prop aircraft requesting intersection departure, is it pilot discretion for the minimum amount of runway length required? Is there a takeoff calculator in conjunction with calculations?
9 votes
2 answers
2k views

How is hypothetical max altitude of a helicopter calculated?

How do engineers calculate the hypothetical max altitude of a helicopter if the mass, altitude and length/curvature of blades are known?
3 votes
1 answer
333 views

Takeoff distances published in OEM manuals

Background For academic research purposes, I have developed a first-principle takeoff performance model that returns a takeoff distance required (TODR) based on the aircraft type (incl. its associated ...