Questions tagged [performance-calculation]
Questions about calculating the various measures of performance of an aircraft.
120
questions
5
votes
2answers
841 views
Can the energy dissipated in a power-off descent be calculated and expressed in horsepower?
If the weight in pounds of an aircraft is known along with its sink rate in feet per minute at best power-off glide conditions, can the horsepower being dissipated by drag as the plane descends via ...
7
votes
1answer
654 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?
0
votes
0answers
70 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 ...
18
votes
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
votes
0answers
56 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
votes
1answer
186 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 ...
7
votes
1answer
351 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
vote
3answers
165 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
votes
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 ...
6
votes
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
votes
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 ...
1
vote
1answer
142 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: ...
1
vote
1answer
53 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 ...
0
votes
1answer
67 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
votes
1answer
299 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 ...
3
votes
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 ...
0
votes
1answer
274 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 ...
1
vote
1answer
68 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
votes
2answers
326 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
votes
3answers
183 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, ...
1
vote
1answer
197 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 ...
0
votes
1answer
319 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
votes
1answer
416 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 ...
2
votes
1answer
334 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 ...
8
votes
3answers
932 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 ...
0
votes
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 ...
1
vote
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 ...
1
vote
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?
1
vote
1answer
602 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 ...
0
votes
0answers
147 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 ...
11
votes
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 ...
4
votes
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 ...
8
votes
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 ...
0
votes
0answers
276 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\...
5
votes
2answers
499 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
votes
1answer
923 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 ...
3
votes
2answers
169 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)
...
6
votes
1answer
379 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 ...
1
vote
1answer
195 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 ...
1
vote
2answers
864 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
votes
1answer
124 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 ...
2
votes
1answer
873 views
How would you use the mental clock code to solve this dead reckoning problem?
Can someone explain the question below in details?
You plan to fly a cross country flight at 2 000 feet at a true airspeed of 120 knots. Your track is 270° (True) and the wind is from 225° (True) at ...
0
votes
1answer
858 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 ...
2
votes
1answer
356 views
How is altitude correlated with true airspeed?
I am trying to understand the BADA 3.0 dataset (specifically I am looking at Performance Summary Tables):
E.g.
What is not obvious to me is why those tables mention only single TAS for specific FL.
...
0
votes
3answers
10k 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 ...
2
votes
2answers
653 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. ...
1
vote
2answers
436 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 ...
1
vote
2answers
133 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 ...
4
votes
4answers
395 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 ...
1
vote
0answers
174 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 ...
