Questions tagged [performance-calculation]

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

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7
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1answer
638 views

Why do we calculate 25% more of TODR?

In general aviation aircraft, we are being told to calculate TODR (takeoff distance required) using AFM and TODR x 1.25. Why do we need the value with 25% added?
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4answers
2k views

Why do we still interpolate in performance tables?

I'm getting my Private Pilot License. In the coursework, we learn about flight planning, which requires looking at performance charts for your particular aircraft. These charts in my case are tables ...
0
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0answers
64 views

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 ...
0
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0answers
52 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 ...
-2
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1answer
180 views

Should a runway overrun be expected if takeoff is begun with one-engine-out?

Multi-engine aircraft have enough power to successfully takeoff if one engine fails after V1. But what if, on a runway equal to the specified takeoff distance, someone decided to roll with one engine ...
1
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1answer
8k views

How to calculate the thrust of a piston or turboprop engine? [duplicate]

This spawns from a related question. Propeller-drive engines (piston/turboprops) seem to always list their output in horsepower or kilowatts, which are units of power. I want to know the engine's ...
7
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1answer
346 views

Why is my calculated seat-miles per gallon of small aircraft higher than of big aircraft?

I've calculated the seat-miles per gallon for three planes. This factors in the speed; it basically means how much does it cost to transport 1 person 1 mile. Plane Seats Cruise (MPH) gph seat-mpg ...
1
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3answers
164 views

What power have I obtained?

I am currently working on a question in aeronautical engineering. The question has asked me to provide the available power. I have calculated the drag, and am given the constant velocity. With that, I ...
4
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2answers
147 views

Are there more refined rules-of-thumb for Top of Descent calculation, than the simple FL x 3?

Forgetting the excellent capabilities of VNAV for a moment and reverting to simpler days, is there a rule of thumb to further refine the FL x 3 rule for Top of Descent calculation, when there are ...
10
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2answers
10k views

Why is "clearway minus stopway" used in V1 adjustments?

Illustrations and/or satellite imagery to explain the difference between clearway and stopway and explaining how they are used by turbine aircraft would be great. From B787 FCOM.
6
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3answers
710 views

Mathematical function in performance diagrams

I have taken upon myself to digitise some scanned old performance diagrams, e.g. roll distance as function of mass and OAT, TAS as function of power setting, etc. The obvious goal is to allow the ...
2
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0answers
57 views

Slotted wing loading and structural analysis

I'm trying to determine moments and forces on a wing with a fixed leading edge slot (trying to verify the Ragwing RW19 wing before starting the project). It's quite straightforward for a non-slotted ...
8
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4answers
2k views

Why aren't large, low-speed propellers widely used?

I am trying to calculate different propellers for the simple case like helicopter moving slow up like 1 m/s or staying/hanging in one place. From generic physics point of view it is more efficient to ...
8
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3answers
905 views

Why do propellers have less theoretical range (i.e. range ignoring impatient passengers wanting to go fast) than jets, despite greater efficiency?

I was playing around with the breguet range equation recently, and came across a suprising result, that propellers have less range than jets, despite having greater efficiency. The range equation for ...
1
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1answer
51 views

What are the best methods for calculating lift during different stages of flight?

Supposing I have the all dimensions of an RC airplane: wingspan, NACA airfoil, aspect ratio, fuselage length, etc., what would be the best methods of calculating the expected lift the aircraft should ...
1
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1answer
132 views

How to calculate TAS and fuel for Diamond DA20-C1?

The PoH for the Diamond DA20-C1 is here: http://support.diamond-air.at/fileadmin/uploads/Canada/Tech_Pubs_DA20-C1/AFM/DA202-C1-Rev-28.pdf. The plane has an MT prop, and the supplement for it is here: ...
0
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1answer
65 views

Replacing or supplementing turbofan with electric fan [duplicate]

Could you replace 2 B747 engines with electric turbofans? Could the 2 standard turbofans produce enough power to allow electric cruise with jets used for take off?
4
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1answer
4k views

How to calculate W/V from true HDG/TRK/GS using a CRP-5 flight computer?

I am currently studying for my EASA ATPL (airline transport pilot license) and one of my subjects is General Navigation. I have stumbled across this question (picture) that has completely stumped me, ...
11
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2answers
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 ...
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4answers
2k views

How is the Max Zero Fuel Weight used in calculating weight and balance?

In some weight and balance apps there is an option to "Use Max Zero Fuel Weight". Having never seen this in any of the aircraft I have experience flying, I am curious how this value is typically used ...
4
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1answer
278 views

What are the equations to compute takeoff and landing distance?

I am flying a Piper 28-336 Dakota. Based on this paper I was able to reproduce the take-off distances from the POH and incorporate the calculations directly in Excel. It can be seen that the effects ...
5
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5answers
19k views

How do you convert true airspeed to indicated airspeed?

Is this something found in the POH? I know there is a IAS and CAS chart.
3
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1answer
234 views

Is the quickest way to reverse direction by turning horizontally or vertically?

Assume my aircraft is flying with Mach 2 and I want to quickly change my direction of travel 180°. So for a horizontal turn flight I found the formula: angular velocity = g* sqrt(n²-1) / v For a ...
5
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2answers
469 views

What is a Second Segment Weight Limit?

I am very interested in the principles of take-off performance optimization. During my research I found an interesting picture, showing the software used by a European carrier. However, the output ...
0
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1answer
242 views

How to calculate Night Flight time for a given flight? [duplicate]

I am currently working on a project (web app) at university to be able to calculate the amount of time spent during night flying. Currently, I have, Departure Lat and Long and Departure Time in UTC ...
2
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3answers
176 views

What is the correct term for the type of performance chart where curved lines are followed?

What is the correct term for the type of performance chart where, from a starting location, curved lines are followed to various reference points to eventually find a solution? For a specific example, ...
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1answer
67 views

What units should use for velocity prediction equations?

I'm not an expert aviation but I'm designing my own RC Plane and I wanted to estimate the maximum velocity using equations (15-20) from this paper. Honestly, I am not quite sure on the units to use ...
2
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2answers
308 views

Does Green Dot Speed Calculation include banking Angle?

I'm wondering, whether the Green Dot- speed calculation in the Airbus PFD does account for the actual bank angle of the aircraft. ...
2
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1answer
315 views

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 ...
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1answer
177 views

Have I made a calculation mistake in this ATPL question that uses the CAP 698 Chart?

I have been calculating this question but I just don't seem to get the correct answer. For this question use Performance Manual CAP 698 SEP1 Figure 2.3. Using the climb performance chart, for the ...
4
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1answer
9k views

What fomula 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 ...
4
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3answers
15k 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 ...
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1answer
562 views

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 ...
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3answers
11k 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....
0
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1answer
317 views

What is takeoff power? [duplicate]

I Am asking about the takeoff power here not how the aircraft takes off. What do I need if I want to calculate the power required by an aircraft to take off? What parameters should I consider?
6
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1answer
395 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 ...
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2answers
110 views

Shall We Consider Reversers in performance Calculations?

Thrust reversers are featured to help slow down the plane after touchdown. Moving the thrust levers aft activates the translating cowl to open, closing the blocker doors. This action stops the fan ...
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2answers
4k views

How do I use the takeoff and landing distance charts in the C172 POH?

Can anyone explain how to calculate takeoff and landing distances using the chart for C172s, and please give me an example?
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0answers
145 views

For Airbus pilots, what is your TOD calculation methodology?

During A330 training, various instructors will have many different types of equations and gateways used to confirm the descent profile and whether or not they are above or below glidepath. The ...
5
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1answer
8k 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 ...
3
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2answers
168 views

Are compressor maps for multistage compressors drawn for one blade row or the whole compressor?

Apologies if this is a stupid question. I am a little confused about compressor maps. Are compressor maps such as this one, drawn for one blade row only or the whole compressor? (source: Wikimedia) ...
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0answers
267 views

What is a good and simple software for calculating propeller thrust and required power?

My main requirements: Calculate propeller thrust with big range of the altitudes (0 - 200 km) or to have air pressure input parameter, which I can type. For example pressure for 152 km is $4.98\...
2
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3answers
2k 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*(...
0
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1answer
887 views

What is the average climb gradient of an aircraft during the takeoff and early phase of a departure procedure?

On chart plates it is written the minimum climb gradient with which an aircraft should climb for obstacle clearance or after ATC request (for traffic flow management etc.). However, since this is the ...
9
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2answers
11k 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 ...
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1answer
194 views

Do takeoff (or other) performance calculations for jet aircraft take into account the type of fuel being used?

Jet aircraft can use any of a number of different fuels:1 Jet A-1 is a straight kerosene, not that much different from what you used to buy for committing arson fuelling portable space heaters. JP-8 ...
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2answers
1k 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?
6
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1answer
371 views

Does one-engine cruise consume less fuel than two-engine cruise?

Scenario 1. A two-engine airliner experiences rapid depressurization and makes an emergency descent to 10,000 ft, and diverts to the nearest airport. Scenario 2. The same two-engine airliner ...
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2answers
836 views

How do I estimate piston aircraft fuel efficiency?

Is there any way to figure out or calculate fuel consumption of piston engines for aircraft? I'm looking at different engines in a book, and while jet engines have useful values like thrust, bypass ...
3
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1answer
120 views

Do aircraft performance figures include corrections for areas with especially strong or weak gravity?

The strength of gravity at the Earth's surface is not constant, but varies from place to place by as much as a few percent: (Image by NASA.) As a result, an identically-loaded aircraft weighs less ...