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Wind tunnel

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rtfm

Well-Known Member
Joined
Jan 3, 2008
Messages
3,900
Location
Brisbane, Australia
Hi,
Well, I have a lot of Q-Cell goop to put on the Razorback this weekend, and a lot of time just sitting around waiting for the resin to set. So I think I'm going to give the wind tunnel a go. My plan is (roughly) as follows:
  1. Acquire the factory's big stage fan (LOTS of blow power there...)
  2. Build a tunnel out of some heavy duty black plastic I have in the shop and attach it at one end to the fan cage, and at the other end to the anti-turbulance box (a box stuffed with straws)
  3. Construct the wind tunnel test area as follows: (1) Foam base, with grooves cut to accept perspex sides (2) insert two perspex sides (3) attach top (perspex if I have sufficient, or if not, plywood) (4) Secure the test area with duct tape, and ensure relatively robust.
  4. Secure the test area to the anti-turbulance box
  5. Sides of the test box will have two grooves into which the rollers attached to a tubular wing "spar" will fit. This is to enable the wing section to roll back and forth in the grooves as drag increases/decreases. The 'spar' will be anchored at the beginning of the grooves with a strain guage ($2-Shop scales - absolutes or actual measurements are not important. I want to measure change, and relative movement under different conditions)
  6. Once the wing section is fitted, I'll attach a $2-Shop strain guage to the TE to measure relative deflection

That's about it.

The wing section will have (1) a fowler flap (good practise and trial/error to get the rails sorted out for the real thing) (2) a speed brake. The idea is to see:
  • How the wing section deflects (both vertically and horisontally) as the flap is extended
  • How the dropping of the speed brake affects the drag and the lift
Benefits of spending my time thus employed:
  1. If deploying the speed brake destroys the lift significantly, now would be a good time to discover this.
  2. It will allow me to experiment with the shape of the flap rails
  3. It will also give me a good way to raise my skill levels before tackling the actual wing with its rails, flaps and (possibly) speed brake
  4. I will use the actual linear actuator and rig up the control linkages as they will appear in the plane. Again, an excellent test/experience bed for the real thing.

So there it is. The project I'll be working on between sanding sessions. Got to keep the enthusiasm levels high during interminable sanding sessions! :)

I promise to take lots of pictures.
Regards,
Duncan
 
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