GIMBLED thrust !

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Speedboat100

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Are there any examples ?

Does it increase complexity, weight and price ?

If so then how much ?

What are the possible advantages ?
 

Speedboat100

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Electric engines are light....and powerful....could I use them as ailerons in a small twin ( leaving the aerodynamic ailerons for good ) ?
 

wsimpso1

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Are there any examples ?

Does it increase complexity, weight and price ?

If so then how much ?

What are the possible advantages ?
Bunches on complexity and price, and adds weight to.

Gimbeled engine thrust is fly by wire, a very big deal to implement safely, requiring redundant power, sensing, processing, and actuation. Cost and complexity.

Going from fixed engine to gimbled engine with thrust through the engine requires a way to structurally carry the engine mass and the thrust and then pivot the system in two dimensions. Weight and complexity.

Another way is to fix the engine but gimble the thrust element. In props, that still requires a pivoting and support system that carries full thrust plus a flexible driveline. In reaction systems, this can be either variable nozzles or steerable nozzles on very hot elements. Weight and complexity.

Stability must still be provided aerodynamically. Unless thrust vectoring approaches thrust to weight ratios of unity, having enough force to effect yaw and pitch control to nominal g limits will be difficult to obtain. In most airplanes the horizontal tail plane must be capable of carrying the weight of the airplane (forces at max g are on that order), and vertical is on the order 60% of weight of the airplane. Maybe with wing mounted vectored thrust, you could handle roll control.

Then there is the whole issue of failure mode management. Partial or total engine power loss means reduced or total control loss, and you take whatever trimmed speed, descent angle, landing spot, and no flare landing the odds gave you. In the middle of Iowa, you might be OK. So what are you going to to, Eject? Full airplane recovery parachute? Where are you throwing the airplane? Really bad failure mode compared to our more nominal "forced" landing.

It is done on rockets, where thrust:weight ratio is big, and significant power loss early in the flight means loss of mission and machine anyway. It has been used for VTOL (Harrier tactical aircraft) , but only for lift and very low speed attitude control, with conventional control surfaces for more nominal airspeeds. Note thrust:weight ratio greater than unity.

Vectored nozzles aft have been done with tactical jets to improve manueverability, particularly at very high AOA. Again, thrust:weight ratios around unity.

This has been played with, and while it can and is done, simply lacks capability in our little airplanes.

Billski
 
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Bille Floyd

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Gimbeled engine thrust , is basically how a trike on a hang-glider works.

Bille
 

rv7charlie

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You mean like the V22? ;-)

A lot of the proposed electric VTOL 'air taxi' designs depend on tilting thrust elements, but I suspect that's not what you're asking about.
 

Vigilant1

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Perhaps we could achieve a gimballing-like effect in a simple way by mounting the engine and prop rigidly to the airframe and then changing the attitude of the entire airframe, thus changing where the thrust vector is pointed. I haven't worked through it yet, but right now I'm considering small movable vanes at the aft end of the airframe to cause the nose to go up, down, left, or right under the control of the pilot. While this won't change the thrust vector relative to the airframe, it will change it with respect to the relative wind, which achieves a lot.
On a separate subject, I have another plan to use simple hinged surfaces near the ends of each wing to modify the wing's camber at those places, causing the aircraft to rotate on its longitudinal axis.
 

wsimpso1

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Gimbeled engine thrust , is basically how a trike on a hang-glider works.
While you are gimbling thrust, the big thing you are doing is weight shift to cause rolling and pitching moments. It works just fine with the engine wide open, with the engine shut down, and everywhere in between. Weight shift has more effect upon airplane attitude than modest pitch angle changes on the prop or it would not be controllable...
 

wsimpso1

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Perhaps we could achieve a gimballing-like effect in a simple way by mounting the engine and prop rigidly to the airframe and then changing the attitude of the entire airframe, thus changing where the thrust vector is pointed. I haven't worked through it yet, but right now I'm considering small movable vanes at the aft end of the airframe to cause the nose to go up, down, left, or right under the control of the pilot. While this won't change the thrust vector relative to the airframe, it will change it with respect to the relative wind, which achieves a lot.
On a separate subject, I have another plan to use simple hinged surfaces near the ends of each wing to modify the wing's camber at those places, causing the aircraft to rotate on its longitudinal axis.
LOL. Vigilant1, be careful, your description may be taken seriously...
 

tspear

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If you only want some partial level of vector, take the ability to adjust the thrust of the prop from a helicopter main rotor.
This would allow you increase the thrust on one side of the prop and decrease it on the other.
Still no idea why you would want this additional complexity.

Tim
 

Victor Bravo

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small movable vanes at the aft end of the airframe to cause the nose to go up, down, left, or right under the control of the pilot.

I have another plan to use simple hinged surfaces near the ends of each wing to modify the wing's camber at those places, causing the aircraft to rotate on its longitudinal axis.
Sir, do you understand that this elaborate scheme of yours represents a rather bombastic claim of being able to exert control over the aircraft in all three primary axes... at once !

Are you further aware that this shocking new method which you are proposing would have the effect of (essentially) using the entire aircraft as a gimbal ? Science fiction, I say.

Someday aeronautical science may advance to the level where such a scheme could be proven to function, but to postulate that it is achievable with today's technical capabilities is... is... nothing less than an affront to the sensibilities of this esteemed group !

(not often that someone can find an excuse to use the word 'affront' these days :) )
 

Sockmonkey

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Co-axial electric props with the whole motor/prop assembly mounted on a gimbal in the nose could do pitch and yaw, while altering the speed of the motors could do some roll. Sorta complicated, but it would replace all your other control surfaces and the runs would be short.
 

User27

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F-35B rear nozzle, designed by Rolls Royce, is an example of gimballed thrust.
I think the X-31 nozzle also, effectively, was an example.
Some of the Russian experimental fighters also had engines that probably could be considered gimballed thrust
 

Speedboat100

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F-35B rear nozzle, designed by Rolls Royce, is an example of gimballed thrust.
I think the X-31 nozzle also, effectively, was an example.
Some of the Russian experimental fighters also had engines that probably could be considered gimballed thrust

Also F-22 may have ?
 

User27

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Also F-22 may have ?
I think only vertical thrust vectoring rather than all-around gimballed thrust.
F-35G has something called a 3 bearing swivel duct to turn the engine thrust through 90deg when in the hover, then some thrust vectoring for control, so perhaps not fully 'gimballed' thrust.
Looking at X-31 the thrust could be deflected for control purposes, so again not fully gimballed.
Perhaps the most significant problem is designing a bearing that will withstand all the thrust loads without being far too heavy to fly?
 
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