Sensing lift on a wing

[Higgler]

I have a proposal that needs to sense the forces on a wing due to air turbulence which either enhances or degrades wing lift.
If I placed many sensors on top and bottom of the wing measuring the force applied to these spots (capacitance change due to air pressure, not G force acceleration), can a computer analysis of those forces give an assessment of the change in lift due to forces caused by turbulence?

i.e. is measuring the forces on different parts of a wing enough to calculated change in lift and then correct for it?

I read the Wikipedia lift description, but couldn't answer my question.

Thanks.

 

[IRstuff]

A variation of the idea floated about using the wings themselves as sensors might be interesting. Accelerometers used in pairs can be used to measure angles, and the long lever arms of the wings would add to the sensitivity of the combined sensor. If the accelerometers can be directly incorporated into the wing structure, the added weight might be minimal.

TTFN

FAQ731-376
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[GregLocock]

Yup, I think we've been distracted. The problem is not sensing turbulence, the problem is maintaining the flight path in the presence of turbulence. It may be that sensing turbulence is the best way of achieving that, but it seems to me that a more powerful stability system is a more conventional approach.

Cheers

Greg Locock


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[aafuni]

Greg I agree, but if you read the link the problem is directly stated to be to measure wing lift. It is a SBIR, that is specifically asking for wing lift detection for mavs.

 

[rb1957]

i doubt that any control system will be fast enough ... sense, analyze, react, reaction takes effect ...

maybe something in the piezoelectric line ?

my sense is that the micro uav is getting blown about by the gusts, scaling things a 10fps gust on a mUAV would be equivalent to a 100 fps gust on a plane, maybe worse ?? you might see this if you measure pressure on the gust side and on the other side of the wing ... very high pressure on the gust side, low pressure on the other.

 

[GregLocock]

With an active control system you'd effectively increase the inertia term for the vehicle, or reduce its stiffness.

Cheers

Greg Locock


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[CastMetal]

A lot of the talk here has focused on detecting lift on a "wing" as in those on a fixed wing aircraft. But Higgler mentioned flying in and out of building this would lead me to believe we are talking about rotorcraft?

If we are talking about up and or downdraft on a mUAV nearing a wall what about measuring the load resistance on the electric motors?

 

[Higgler]

The proposal says microuav and discusses Lamb vector measurement on the wind/body. There is no mention of rotocraft.

from the proposal request
PHASE I: Identify and define the potential of such biologically inspired sensors to more directly sense the critical parameters controlling lift, including total circulation or the integrated Lamb vector. Design a concept for equipping small and micro Unmanned Aerial Systems with equivalent capability to sense and respond to small scale turbulent motions in the atmosphere

 

[BrianE22]

If you could see what the air was doing before the UAV entered it then you could make decisions. Maybe Doppler Radar?

It and the computer and software would probably be more expensive than the UAV but then this is the military.

 

[Dan320]

My suggestion (for what it is worth) is to attach small strain gauge-like "feathers" to the wing surface. This would mimic a bird wing where I suppose the bird has some input as to when the feathers move out of their streamlined position, indicating stall or reversed airflow.
Lots of input channels, but who said it would be easy?
See attached sketch. I do not know if weight will be a problem, maybe you would need to develop the "strain-feathers" as a separate project. Sounds like a lot of fun...

 

[midsidenode]

Look at this technical support package from Dryden Flight Research Center. The toolbox is designed to measure local and global unsteady aero load distribution with distributed sensing.

http://www.techbriefs.com/component/content/article/8990