Questions tagged [aircraft-performance]

Aircraft performance covers areas such as the amount of runway required to takeoff or land and how fast an airplane can climb or descend.

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3answers
69 views

Why are true and indicated airspeed different?

So, I understand that True air speed is the motion of aircraft relative to air around it. And, indicated airspeed is speed arising due to dynamic pressure. Considering a true airspeed of 100 knots, ...
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1answer
139 views

Can an aircraft climb with the thrust line below the line of flight? [closed]

"Downthrust" is a common engine mount feature of propeller driven aircraft, models and full scale alike. From model building experience and flight, downthrust, angling the (tractor) engine ...
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Flex temperature isn't actually “fooling” the FADEC, right?

I'll be using Airbus terminology here because that's what I know, but I guess the concepts are universally applicable. The way I understand flex temperature is: It's a user interface for pilots to ...
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1answer
186 views

Is it possible for Mig 21 at corner speed to extend the flaps to minimize the turn radius? Or this is not an option?

The corner speed is around 330knots if you want to turn better than the enemy is possible to lower the flaps?
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1answer
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Did the Mig 21 have differential stabilators to help the ailerons?

The MiG 21 had all-moving tailplanes or stabilators. When rolling, did one stabilator pitch up and the other down to act as secondary ailerons and help the main ones on the wing?
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4answers
778 views

What is the difference between nautical air miles and nautical ground miles?

What is a simple way to understand the difference between the nautical air mile (NAM) and the nautical ground mile (NGM)? How does the wind affect the net displacement of the aircraft as that is the ...
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0answers
84 views

Why are the wingtips of the Fairchild-Republic A-10 bent downward? [duplicate]

Why are the wingtips of the Fairchild-Republic A-10 bent downwards?It is subsonic aircraft .
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0answers
73 views

How much thrust does the Lilium aircraft produce?

I have been researching the Lilium aircraft and can’t find information about thrust. An early version of this aircraft was 2 seats with a loaded weight of 1,400 lbs, 36 ducted fans and 320 kW peak ...
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20 views

How can we find maximum lift coefficient of Airfoil?

I am trying to find the maximum Lift coefficient for airfoil NACA 64A-404. I chose this airfoil for wing. I am stuck at finding the Clmax. I tried to use javafoil but javafoil is showing Cl less than ...
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1answer
35 views

How the maximum service interval is related to UAVs?

I´ve been reading about the aircraft´s maximum service interval but this concepts is hardly related to the day to day aircraft (civil and military ones of course). How does this concept is related to ...
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2answers
93 views

Does the flap settings for the best lift/drag ratio change with speed on the Diamond DA20-A?

As I've recently started time building in DA20, I've noticed the AFM suggests flaps at T/O for a glide. Being very intrigued by this I run across this post. Although I appreciate Peter's reply that ...
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1answer
89 views

How does the RQ4-Global Hawk improve stability? [closed]

I have seen several videos recorded from an UAV in which the stabilization of the camera is almost perfect. Cameras are installed in a gimbal, of course, but do new drones introduce some new ...
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1answer
188 views

Is the war pilot obligated to fly the same plane daily or must he change the plane according to every required mission? [closed]

Can the pilot change his plane, or can he fly in any plane, obediently, to the same plane as the one trained on it?
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2answers
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How can we physically define reynold number variation in terms of characteristic length? [closed]

How can you define it physically that greater the characteristic length in $Re=\frac{\rho v L_c}{\mu}$ greater the Reynolds number. Like on wing surface $Re$ is higher than the horizontal tail surface ...
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2answers
193 views

How to compute thrust to weight ratio of a Cessna 172?

Cessna 172 has weight about 1 ton and it's engine produces about 213 Kg of thrust, and it flies great. So if I make a plane with a weight of 100kg including pilot and fuel so will 15 kg thrust good ...
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What are the disadvantages of fitting underwing flaps to a Mirage III/5 fighter jets to lower landing speeds?

The Mirage III / 5 series of fighter aircraft are versatile aircraft, but has a high approach speed of 180 knots and a high landing speed, requiring long runways. Underwing flaps, like those of the ...
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1answer
93 views

Calculating thrust and required propeller size for a given engine power

I am looking to build an Airplane, the weight of Airplane will be around 20 to 25 kg and I am going to use a 70cc motorcycle engine as an Airplane engine. I want to know how I can calculate the ...
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1answer
102 views

How does fuel economy quantitatively depend on altitude for a jet?

We already have a few questions and answers about the qualitative effects of altitude on fuel economy: How do I determine the best altitude to fly for fuel economy? Why does fuel consumption decrease ...
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0answers
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VLM at High Speeds and High Angle of Attack

I want to analyze a plane of the size and speed of a commercial jetliner. I have made the model of it on OpenVSP. I am using VSPAero's Vortice Lattice Method for the same. I want to analyze the plane ...
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1answer
53 views

Where can I look for news regarding what's happening in aviation around the world? [closed]

Websites or magazines which keep me updated and where I can gain knowledge on what's happening around the world. Apart from International Airport Review, I'm already on that. Thanks
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1answer
38 views

Is the ratio of HP to weight constant for identical air frames of different sizes? (See Scenario)

In my head it seems logical that there would be a proportion between engine HP and empty weight. For example, the Wright Flyer weighed around 600 LBS empty and had a 12 HP engine. If I were to make an ...
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2answers
327 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 ...
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1answer
61 views

What is the approximate range of the Pelegrin Tarragon?

I recently read about the Pelegrin Tarragon ultralight aircraft made in my country, and got interested in it. Is it possible to have a reasonable estimate of the average distance you could cover in ...
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2answers
65 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
104 views

Is rudder deflection sufficient to maintain directional control on the runway at high speed, or is nose wheel steering needed?

If a fighter jet veers off the runaway, is nosewheel steering needed to counter, or can directional control be maintained with the rudder deflection alone? Is there a chance that the rudder ...
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1answer
57 views

Is “balanced field” defined with or without an engine failure?

I’m wondering what exactly means a balanced field in terms of aircraft performance. From what I know it means that TODR=ASDR, also it is minimum field length required. But I do not know whether this ...
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1answer
79 views

Why isn't Vy lower than the speeds for best L/D ratio and best glide ratio in an airplane with a piston engine and a variable-speed prop?

This answer to a related question implies that if the power available were constant regardless of airspeed, Vy would occur at approximately the angle-of-attack that yields the minimum sink rate with ...
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1answer
145 views

Is it better to increase speed in a climb? [duplicate]

In straight and level flight, lift is determined by speed and angle of attack. If we are heavier, we must go faster to generate more lift, at the same angle of attack. At the same speed, angle of ...
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1answer
46 views

Can TAS at different altitudes be calculated if only one performance point is given?

If the POH only gives TAS at only one altitude, can we calculate the TAS at other altitudes? Here is a snippet from the POH of Remos GX. If we set the RPM to 5,200...
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33 views

what are the advantages and disadvantages of conventional tail configuration? [duplicate]

I amd a student and I dont know much. So,I need the pros and cons of having a conventional tail configuration over other configuration.
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1answer
146 views

In an F-18, how do rudders deflect during cross winds and gusts? Can rudders be deflected by different angles?

Deflection of rudders can balance moment about the centre of gravity. I have thought of non-symmetric deflection of rudders so that net sideward force is create to balance the moment about the center ...
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32 views

What is the general trend of payload fraction for an RC propeller plane?

What is the general trend of payload vs total weight for a radio controlled propeller aircraft? I am simply using this formula: $$Wo = \frac{Wpayload}{(1-((We/Wo)+(Wp/Wo)))}$$ I could get We/Wo (...
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1answer
92 views

How much runway does an amphibious Cessna Caravan require for VFR part 135 operations?

I am trying to determine the length required for us to build a simple paved runway for a Cessna Grand Caravan EX Amphibian to depart for water landings and and return (VFR/VMC only, Part 135). ...
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3answers
148 views

Can one trim same AOA at a higher airspeed to climb? [closed]

There has been some discussion in recent questions regarding climbing technique and optimization of the Lift vector (and the resultant vertical Lift vector). Some writers claim the lift vector must ...
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0answers
23 views

AltFlap switch in F16 jet fighter at various stages in flight

If you apply ALT Flap in F16 the flight quality is somehow similar to the CATlll or TO/Landing gain (lower max AOA available - only 18 degrees - , roll rates halved) because this is emergency mode. ...
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1answer
189 views

How can I calculate the relationship between propeller pitch and thrust?

I am trying to design a WWI propeller so I started calculating. The propeller comes with a specified pitch of 1.75m. The engine is supposed to run at around 1900 rpm and 147kW. These are most likely ...
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3answers
254 views

Are there aircraft that fly without fuel or electricity?

I was browsing through Wikipedia when I saw this: An electric aircraft is an aircraft powered by electric motors. Electricity may be supplied by a variety of methods including batteries, ground ...
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2answers
255 views

How to reduce the noise of the supersonic passage(bang)?

as you know the transonic phase is often associate with the bang. The principal cons of the transonic phase is the noise,it's why there is not supersonic passenger aircraft( cause the end of the ...
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1answer
106 views

Would it be beneficial to limit AOA in fly by wire type a/c like F16 jet in dogfights? [closed]

Would limiting the angle of attack to a maximum of 13 degrees by the fly by wire system help pilot gain advantage over his/her enemy during aerial one to one combat? Using such limits would reduce the ...
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2answers
9k views

Why does camouflage make some planes fly slower?

Why does camouflage decrease some airplanes' speed? I have noticed that some planes fly slower with camouflage than without it. For example, when the RAF applied camo on the P-51 Mustang, they noticed ...
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225 views

First Boeing 757-200 N757A 'Catfish' was modified with a Canard foreplane. How did it behave?

The aircraft had these changes made around 2006 to act as an F-22 Avionics test bed. One would expect that the fore plane changed many performances of machine, including take off and landing attitude ...
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52 views

How to choose airfoil for High Subsonic small UAV?

I am trying to make a concept for a small UAV. The UAV shall be flying at Mach=0.75 , shortly 0.9 For this, I am looking for an adequate airfoil, which allows me, to avoid Mach=1 on the airfoil. From ...
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1answer
86 views

What does performance speed refers to? Aircraft performance in general

For example C172R specifications: Cruise speed:122 knots What does this mean? Maximum achievable Indicated airspeed At specific conditions? Another example - rate of climb: 721 ft/min For what ...
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1answer
104 views

What is the climb-out angle of a twinjet upon one engine failure scenario?

Take a typical 737-800 or A320 at MTOW how much difference in take off angle does a 1 engine out failure scenario make, compared with a normal 6-8 degree take off angle with full engines.
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117 views

Does the phrase “.78/280/250” have a standard meaning to an airline pilot, in the context of a long descent?

Does the phrase ".78/280/250" have a standard meaning to an airline pilot, in the context of a long descent? Specific context-- the table in this answer-- Is the descent performance of the PMDG 737-...
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1answer
1k views

What is an airliner's “green dot speed”, and how does it vary with weight, and why?

A related question told us, quoting from an Airbus performance manual, Green dot speed (minimum gradient) is a function of weight. Comments under the question stated that the "green dot speed" ...
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2answers
2k views

Why does an airliner have a shallow descent when heavier, opposite to gliders with ballast?

Gliders utilize water ballast to, among other things, descend faster: But sometimes you need to get down fast: This is when water ballast is added. In airliners however, the heavier the plane, the ...
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Why does increasing a glider's weight using water ballast improve its speed and performance? [duplicate]

I was studying gliders and how they fly. There is a point that's not clear to me: why does using water ballast improve the performance/speed of a glider? If I understand correctly, my glider jumps ...
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1answer
61 views

Which Velocity is used to measure Dynamic Pressure?

Suppose an airplane is flying in windy conditions. Now, for the calculation of the dynamic pressure should I use the relative velocity or the absolute velocity as the free stream airspeed?
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1answer
7k views

Why does the Pratt & Whitney 747 have an extra engine on the right side but not left side? [duplicate]

What’s the purpose of this design, and why only on one side?

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