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Flap deflection

Chris Santschi

Active Member
Whats the best way to measure deg of deflection for the flaps? I have some markings that i would like to put on that show 10-20-30-40 deg down flap, by looking from the cockpit. like the P-51s used...

Chris RV 8 Second Chance
Festus MO.
 
I used the smart level digital level for aileron, flap, elevator and trim tab deflections. You can zero it to match the "in trail" position and it will then measure deflection from that point.

Jeremy Constant
 
For my evelavors I used a smart-phone app I found for free. I first verified it was accurate then just held it to the top surface of the elevator.
 
From your post I think you mean in flight

I just look at them and only use two positions full down or full up. As I approach the airport I start slowing to flap speed. If I'm on base or downwind etc., and I'm not at the top of the white arc I pull up the nose enough to slow appropriately and hold the switch down untill the flaps stop moving then I trim and make adjustments with slips or power to set up for a good landing. I do not use any intermediate flap settings and saw no reason to in the 7 years I been flying our RV-6A. Your Rv-8 may be different but I sorta doubt it.

Afterthought: If you are talking about rigging, I leveled the airplane canopy deck plane ref the Earth then uses an inclinometer (sp?) to check the flaps and control surfaces to assure the minimum range requirements were met. Initially they were not and some adjustments were required.

Bob Axsom
 
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Flap settings

Thanks for all the advice. Bob I pretty much do much the same as you ,slow up ,put in some flaps and when on base or final full flaps..trim and power..

Chris Santschi
 
I put a piece of black tape on the flap visible from the pilot's seat. When you first see the tape, it's 15 degrees, when the thickness of the tape is done (at the far edge) it's 25 degrees and then full deflection. Put the mark in place before the protective tape along the length of the flap.

I had both flaps set up (retracting and extending as I wanted) before measuring with a smart level.

Dan
 
I am going to do exactly what Dan says in the last post and is shown here on Steve Sampsons's very good RV-4 website. As Steve says, why complicate matters by adding electronics that will go wrong and will add weight.

OFPSS



OFPSS is Steve's jargon for Optical Flap Position Sensor System. It relies totally on the mark 1 eyeball and it is cheap and light. The fact that it is light swings it for me.
 
Even that's OTT Anthony :eek:

Downwind, put out "a bit of flap" (2-3s of motor). It will reduce the stall speed / make speed control a little easier, but I challenge anyone to notice any difference between say 10deg and 25deg ;) On final add the rest (until motor stops) for drag.

If on takeoff you feel a "specific" amount is required, then look left, full right stick and flap until the flaps and aileron line up - lighter and simpler still ;)
 
Speaking of flap deflection...

...there are several posts telling of an incident where the flaps are over extended and catch on the trailing edge of the upper wing skin. My flaps extend to 40 degrees and I cringe at the thought of them catching on the wing skin. Is the 40 degree travel what you folks are seeing and if so do you experience any issues with that travel limit:

As an aside I plan to limit flight to 30 degrees anyway but I?m sure those folks who had the incident also thought they were limiting the travel.

Thanks,
Don
 
I don't remember the angle

I set mine at whatever the Van's document specified and it wasn't even close to poping the leading edge of the flap skin out from under the wing skin. It seems like a really unconscious builder/tester that would run the flaps all the way down and not notice that they were not rigged for safe operation, actually pop them out then reverse the direction to bring them back up and catch the trailing edge of the wing skin. The leading edge of the flap skin should have bent down surface from the a normal skin leading edge curve.

Bob Axsom
 
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