Questions tagged [aircraft-design]

Questions about the different choices that aircraft designers (typically aerospace engineers) make in order to create an aircraft.

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7
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2answers
2k views

Why do the engine nacelles on the P2V Neptune extend so far back?

I was studying a picture of a P2V Neptune seen from below, and what struck me was how far back the engine nacelles reach. Unfortunately, I can't find that original photo but this one shows what I'm ...
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0answers
39 views
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2answers
146 views

Would a Helium Filled Flying Wing Design Drone Fly Farther?

I'm wanting to build a flying wing designed drone and I'm wondering if I were to fill the fuselage with helium if it would improve it's range.
7
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3answers
219 views

Why do X-wing configurations missile/guide bombs use symmetric airfoils?

From all the missiles/guide bombs I have come across, I've always observed that a symmetric airfoil is used for both the wing and tail. Why not have a cambered airfoil for the wing and a symmetric ...
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1answer
47 views

How to decide the diameter of a propeller and number of propellers needed in a UAV I am designing? [closed]

I want to design a turboprop aircraft. I know all the design parameters such as lift, thrust, weight etc at a given flight stage. I want to know what the size of the propeller should be.
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1answer
109 views

Are complete design reports of military aircraft ever published? [closed]

For old aircraft like WW2-era fighters, are such reports ever formally declassified for academic use? Where can I find them?
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2answers
112 views

Will my CRI CRI twin engine plane fly if I replace the engine with a single 15hp gasoline engine? [closed]

I'm using a lighter materials to rebuild plane, to cut down plane weight to 56kg and a 1.2m 3blades propeller.
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0answers
64 views

How to calculate rotor dimensions and other specifications for a flying armored train [closed]

Some friends and I are creating blueprints for a theoretical helitrain tank(not sure what else to call it). It’s meant to be a train-tank-helicopter hybrid. Effectively a chain of flying tanks with ...
5
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3answers
216 views

What purpose do wing root seals serve?

What is the use of wing root seals? What kind of leaks are possible without having wing root seals, and if the seal is broken what kind of issues can airplanes face?
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0answers
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Is the Phoenix's airport a non-standard one or Bombardier CRJ? [closed]

Today, I was reading this news: It’s so hot in Phoenix that airplanes can’t fly And then this article: Why Phoenix's Airplanes Can't Take Off in Extreme Heat In this article; we see this line: ...
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3answers
191 views

Can control surfaces for slow aircraft be 3D printed?

Can control surfaces for slow aircraft be 3D printed or even just printed as a core and then wrapped in fibreglass or carbon fibre? I understand that 3D printing of wings, etc. is pretty common in the ...
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2answers
97 views

See-through/transparent aircraft [closed]

I am a pilot who loves the aviation experience. Can we build a full see through plane using material as strong as the current materials used to build the body of an aircraft. Is there research or work ...
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0answers
48 views

Boundary layer thickness calculation

I have tried to calculate all the losses associated with the serpentine intake to calculate the total pressure recovery. I have considered the frictional losses, pressure loss due to bend, approach ...
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2answers
2k views

Do manufactures list the maximum speed of an aircraft based on its theoretical maximum speed or dive speed?

I know that the absolute maximum velocity of an aircraft is based on the thrust available. However the aircraft is usually limited beforehand by other speed limits such as dive speed and Mach Never ...
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1answer
76 views

What is the Mach Never Exceed number for a C-130J Hercules under ISA conditions (approximations are welcomed!)

I am looking for the Mach Never Exceed number for a C-130J Hercules so that I can create an approximate 1g envelope. Does anyone have any idea what this can be? I am trying to find the value for ...
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2answers
3k views

Why are there double hinge lines on the rudders of the Grumman C-2?

Why are there two sets of hinge lines on the rudders of the Grumman C-2? A photo from the related ASE question Why does the C-2 left inboard stab not have a rudder? Why would two hinge lines provide ...
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0answers
39 views

What are typical control surface deflection “rate” limits for transport airplanes?

I was wondering if anyone knows what are some typical control surface/actuator deflection "rate" limits for transport airplanes (i.e. aileron/elevator/rudder deflection rates)? I haven't ...
0
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1answer
24 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 ...
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0answers
84 views

Is the location of the chines on the two seat F-16 variant is the same as for the one seat one?

Is the location/length of the chines (the cobra hood looking) on the two seat F-16 variant the same as the ones on the single seat variant? The two seat variant has a longer cabin, so it must be ...
14
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4answers
5k views

Why are 3- or 4-seat gliders so rare?

Sailplanes capable of climbing in rising air (not troop transports, which can only descend after the towrope releases) have one or two seats. I know of only one type with more, the Schweizer SGS 2-32 ...
0
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1answer
95 views

How do I determine the diameter of my propeller at high altitudes? [duplicate]

I'm designing a electrically propulsed HALE UAS and I need to find the diameter of my propeller to find my thrust. Is there an equation for propeller diameter that doesn't rely on knowing my thrust or ...
41
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3answers
8k views

Is it dangerous for a supersonic aircraft to fly at exactly Mach 1?

If a plane that is designed for supersonic flight, say the Concorde, kept flying at exactly the speed of sound, would there be any danger in that? If so, what could get dangerous at constant Mach 1 ...
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1answer
98 views

What are the difficulties in building transonic airliners?

If the sonic boom is an issue, why don't we build airliners that are capable of flying just below Mach 1? Big airliners fly at Mach 0.85 at most, and the record for current sub-/transonic civilian ...
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1answer
81 views

What is the difference between aircraft integration and assembly?

I have never had a clear understanding of the difference between aircraft assembly and integration. My understanding is that putting together the airframe alone is assembly and putting together the ...
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1answer
81 views

What thrust is used for thrust to weight ratio?

Performing some preliminary calculations for an aircraft design I have and was wondering what thrust I should use to calculate thrust to weight? The thrust calculations I have, vary due to speed (...
2
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2answers
162 views

Where is the center of gravity on a tiltrotor?

From what I understand, the CG of full-sized fixed-wing airplanes need to be forward of the wing's center of lift for stability. But the CG of a helicopter must be directly below the rotors since it ...
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2answers
151 views

Why do privater jets often fly at or above FL 400, but large commercial aircraft are usually in the range of FL 300 to FL 400? [duplicate]

With rare exceptions (like the Embraer business jet, which is simply their commercial jet with a different interior), almost all private jets fly in the more rarified air above FL 400. But, if its ...
2
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1answer
213 views

Why are some modern military trainer aircraft so bulky?

Modern military trainer aircraft are a lot wider and bulkier than the previous generation. Especially the canopy looks oversized. You can see this in the Boeing/Saab T-7 Red Hawk, Alenia Aermacchi M-...
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1answer
90 views

In wing design, how is factor of safety related to G-limits?

What does factor of safety mean with regard to the maximum G force an aircraft is rated for? Does a rating of 3Gs mean the same as a safety factor of 3? Or is there some extra margin?
2
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1answer
111 views

Optimizing the airplane for best cruising altitude and velocity

In the conceptual phase of the design, I am optimizing various entities of an airplane for the best cruising altitude and speed to reduce the cost, which also includes MTOW and fuel weight. Consider a ...
4
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2answers
329 views

What made Concorde so heavy?

The Concorde burnt five times more fuel per passenger mile than the 747. A huge contributor must have been the immense empty weight per seat, three times that of the B747. B747-300 Concorde Empty ...
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2answers
6k views

How exactly did engineers come to the final design of jets like the F-16 or SR-71?

I ask this question because I read somewhere that SR-71 was designed in 60's with hand calculations and drafters and when engineers later tried to improve the design with modern computers they found ...
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2answers
178 views

What justifies a biplane over a braced monoplane?

Biplanes became the first airplanes to enter service due to their structurally efficient design being more suitable for the weak materials then. This efficiency comes from the two wings acting as the ...
2
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1answer
120 views

Is a flying wing optimal for high altitude craft?

One of the biggest problems with flying wings is their sheer thickness, which creates excessive drag. However, since high altitude craft need bigger (and thus thicker) wings anyway, and since weight ...
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1answer
216 views

What surface materials do airplanes use to reduce friction?

Full swimming body suits were banned from Olympic Games a few years ago because some materials have less friction than skin and contestants that could not afford gear to increase their performance ...
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1answer
128 views

What should be the thrust weight ratio for takeoff? [closed]

I am doing some calculations for preliminary design of an airplane and I was wondering how I would go about determining the minimum thrust to weight ratio needed for the aircraft to takeoff. Which ...
6
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1answer
2k views

Why do propellors have white markings on their tips? [duplicate]

Why do propellors have white markings on their tips? Here are a couple of examples:
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8answers
10k views

Why don’t airplanes use turn signals?

Why don’t airplanes use turn signals like cars do? Would this improve safety for ground operations at uncontrolled airports? Could a similar concept be used to indicate in air maneuvers? For example: ...
19
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4answers
7k views

Why don't modern fighter aircraft hide their engine exhaust?

In many photographs, the F-4's unique geometry hides one or both engines. I've been told that this is one of the terrific accidental features of the F-4, as it would help shield the hot exhaust from ...
2
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0answers
46 views

How do I find the shear center of an unsymmetrical airfoil?

I'm quite a newbie of these systems and I am designing the wing box of a drone. I know where I want my shear centre. However, I have been trying to determine the shear centre of my idealized airfoil. ...
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0answers
101 views

How did the FAA decide that firewalls should resist fire for 15 minutes specifically?

I'm searching for information on where the criteria of 15 minutes come from, in which the firewall is subjected to by a flame of 2000 °F (according to the now-obsolete 14 CFR 23.1191). I know that ...
9
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2answers
3k views

Why do sailplanes have such large tails?

Since a sailplane is focused on performance - what with tricky laminar flow airfoils and all. Eo why this Instead of this It looks to me like that long tail is needed to balance the cockpit. Buy ...
0
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1answer
202 views

Would an airliner fly more efficiently on a fatter wing at a low altitude?

Flying at 1000 ft, would giving an airliner wing more girth but not length, allow the plane to fly more efficiently than it normally would at that height? Yes, airliners fly best around 35,000 ft, but ...
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0answers
94 views

Why aren't isentropic noses and tails used in supersonic aircraft?

An inside out paraboloid would theoretically produce isentropic compression for an inlet cone. But this question is about nose and tail cones on fuselages, and leading and trailing edges of wings. An ...
1
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2answers
215 views

For jetliners, how is a swept wing justified over a thin wing?

For a given speed, a swept wing is a fatter alternative to a straight, thin wing. But why? Does not the sweep lengthen the wing and make it heavier? Is the swept wing chosen for the extra fuel tank ...
3
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1answer
81 views

Induced drag reduction from tandem wing

Induced drag is proportional to the square of span loading. The normal method to decrease it would be to increase span. This, however, leads to an exponential weight increase. So, my question is, if ...
2
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0answers
147 views

Why aren't rudders automatic? [duplicate]

Why aren't rudder pedals automatic or connected with ailerons to keep the nose of the aircraft coordinated with the turn its entering? Wouldn't this make for an easier and smoother to operate aircraft?...
1
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1answer
59 views

Difference in lift generation for a swept wing and straight wing in subsonic condition

Would there be any differences in lift for a straight wing and swept wing (front or back) with the same airfoil cross section, same chord length, same wing span, and same area when flying in subsonic ...
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3answers
233 views

Why are aircraft not equipped with nose cargo doors when being converted from passenger to cargo variant?

I'm trying to find any substantiation / design justification why none of the OEM/STC holders are able to provision nose cargo doors on A321 / B757 / B767 / B777 fleet as part of P2F (passenger to ...
5
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2answers
483 views

In a tailwheel plane, which design elements affect the propensity for a ground loop?

In comparisons between conventional gear vs. tricycle gear aircraft, it is generally explained that the CG location relative to the mains is a necessary condition for ground-looping. But there's very ...

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