54
votes
Accepted
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
Interesting question. Purely empirically, it is the lift-to-drag ratio you are looking for. If you take this value as given for any particular aircraft, you have a direct answer for how much more ...
- 2,766
29
votes
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
In a traditional aircraft the majority of the power from the engine is used to keep the aircraft moving forward at a certain speed. Very little of that power is actually needed to create lift.
...
- 4,886
29
votes
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
With regard to energy expenditure and power,
for a given amount of force that is to be produced by accelerating
an air mass,
more power is required when you accelerate a small air mass
in each period ...
- 1,306
19
votes
Accepted
Why do propellers on aircraft have a slight offset angle?
The direction of rotation of the propeller introduces an asymmetry which designers try to mitigate by adding more asymmetries. Specifically, a right-turning tractor propeller (clockwise from the pilot'...
- 237k
19
votes
Why is Russian super-maneuverable thrust vectoring more prevalent than American?
This is a case of divergent design, and you can't know the answer without asking why current aircraft are designed they way they are.
Following the work of Col. John Boyd in the 1960's in developing ...
- 191
18
votes
How much thrust is lost through a curved exhaust nozzle?
For the F135 engine in this photo, thrust in hover is only about one per cent less than maximum thrust, if Pratt & Whitney's data sheet is to be believed.
Maximum Thrust Class 41,000 lbs
...
...
- 12.9k
16
votes
Accepted
Why is Russian super-maneuverable thrust vectoring more prevalent than American?
Part 1 - TVC
Perception
The US also ran several programs with TVC:
F-15 STOL/MTD and ACTIVE.
F-16 VISTA / MATV. AVEN:
F-18 HARV (High Alpha Research Vehicle)...
- 3,984
15
votes
Why don't aircraft use gimbaled engines instead of flaps?
Historically, flaps and control surfaces were moved manually: The pilot would move a stick, a control column or pedals, and pulleys or pushrods would transfer this force to the control surfaces. To do ...
- 237k
13
votes
Accepted
Are fixed wing aircraft with gimbal thrust feasible?
Could you create an aircraft using an jet engine/propeller/ducted fan on a gimbal? Sure you 'could'; it is feasible by the laws of physics. But just because you can does not mean that you should.
...
- 75k
11
votes
How does the F-35 hover?
The F-35 has what is called the Rolls-Royce LiftSystem. This Contains one lift fan in the middle of the aircraft, and a rotating jet exhaust to provide vertical thrust, and two rotating nozzles to ...
- 323
10
votes
Accepted
At what altitude does a wing become useless?
Maybe wings never mattered...
Altitude:
The answer depends a bit on the design of the craft in terms of control surfaces/wings. Atmospheric reentry begins at the Karman line at an altitude of 100 km ...
- 102k
10
votes
Accepted
Can a F-35 shoot while hovering?
No, it cannot, at least there is no reason for it to do so...
A) The stick while in "hover mode" does not control the pitch/roll of the aircraft, but the forward/lateral position of the aircraft. ...
- 36.2k
10
votes
Accepted
What is the effect of thrust vectoring effect on the rate of turn?
The standard equation applies to any coordinated level turn (so that the G felt is "straight down" to an occupant of the aircraft, in an aircraft frame of reference). Matters not how it's ...
- 53.6k
8
votes
What is the effect of thrust vectoring effect on the rate of turn?
With thrust vectoring you no longer turn (as in: the wing creates the force that accelerates you in the desired direction) but you do post-stall maneuvering. Next, you need to distinguish between ...
- 237k
7
votes
How does the Urbanaero flying car move forward?
It would fly forward the same way a quadcopter does: have the aft motor controller increase current, thereby increasing aft fan lift, creating a pitching moment downward and moving the fan arcs out ...
- 75k
6
votes
Are fixed wing aircraft with gimbal thrust feasible?
Sure you could, but why would you want to? There's no inherent benefit to be had in vectoring thrust as opposed to using control surfaces. It doesn't simplify things to any extent, it just makes ...
- 54.4k
6
votes
What does it mean "two plane thrust vectoring nozzle"?
This statement is using "plane" in the mathematical-geometric sense, which is of course very confusing when we talk about a part of a "plane" in the "flying machine" sense.
So, a "one-plane" thrust ...
- 6,166
6
votes
How much thrust is lost through a curved exhaust nozzle?
A 90 degree bend in a pipe where the radius of the bend is of order ~one pipe diameter creates the same pressure drop as a length of that same pipe of order ~ten to fifteen times the pipe diameter.
- 22.2k
4
votes
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
If we ignore the losses, maintaining the aircraft at a given altitude requires no power, since no work is done on it. It does, however, require a force, and you seem to confuse force and power. The ...
- 253
4
votes
Why is Russian super-maneuverable thrust vectoring more prevalent than American?
A very important reason is stagnation.
US aircraft development has pretty much stopped cold in the mid-late 1980s, with just the F-22 and F-35 entering production since, and those decades overdue.
...
- 16.3k
3
votes
Why do propellers on aircraft have a slight offset angle?
Some planes have this designed into the engine mounts to offset the more pronounced left turning tendencies of larger engines. "Large" in this case is a 400/500 series Lycoming or Continental.
...
- 6,066
3
votes
Are fixed wing aircraft with gimbal thrust feasible?
Gimbaled thrust in 'rocket speak', is equivalent to vectored thrust in 'aviation speak'.
Many modern military aircraft use thrust vectoring in order to improve performance, particularly in tight ...
- 31
3
votes
How does the F-35 hover?
Actually, the picture above is USMC (US Marine Corps),s F-35B, which he have a STOVL (Short Take-Off and Vertical Landing) capability. That aircraft hovers using a Rolls-Royce Allison fan to lift ...
- 31
3
votes
Can thrust vectoring be used to enable the use of flaps on tailless delta-winged aircraft?
No, for several reasons
What you want is to compensate for the additional lift from downward deflected flaps at the back of a flying wing with vectored thrust. As @Sean points out this will not bring ...
- 237k
3
votes
Accepted
Why don't modern F-16s incorporate the VISTA thrust vectoring?
Thrust vectoring adds weight, cost and complexity, and the benefit isn't important enough to outweigh that.
Various aircraft have been used to experiment with thrust vectoring, but the list of thrust ...
- 73.8k
3
votes
How does the Urbanaero flying car move forward?
The Urban-Air question, with provided downlink, does seem to show a viable twin rotor design that may provide a more stable flying platform than that experienced with the Avro VZ-9 Avrocar concept ...
- 21.3k
3
votes
How does the Urbanaero flying car move forward?
I can indeed see the two large propeller fans inside the craft, with guiding vanes to direct the exit flow left/right (cannot detect any fwd/aft adjustment). The propellers provide take-off lift, ...
- 62.9k
2
votes
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
The way "basic" flight was always explained to me is that because of the shape of the wing, air over the top has further to go, thus is "stretched" the air under the wing has less distance to travel. ...
- 797
2
votes
Are wings any more efficient at creating lift, versus orienting the engine's thrust downwards?
Skimming through the answers, I'm missing a very simple approach to explain the difference:
Listing the inefficiencies for both design solutions
Fixed wing
non-lift-producing drag - Some of the drag ...
- 21
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