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Flap rigging question

titanhank

Well Known Member
I did not build my rv6, but i am tweaking it for better speed. The flaps are rigged like the pictures and i am not sure if it is right. It looks like i am flying around with flaps out 2-3 degrees. This may explain some of the 5-8mph tas i am searching for. It has a 160hp 0-320 with catto 3 blade 67x70" prop. At 8000ft density altitude at WOT and leaned for max rpm, i am turning 2650 rpms doing 182.5 mph tas. The static rpm is 2200rpm, so i think the prop is correct, but the drag profile is too high. What are you guys thoughts on this flaps setup? I have not checked the incidence, but i have removed the wingtips and made a fixture to check the aileron and flap alignment to the chord using the tooling holes. It is perfect and the plane flies laser straight hands off. Do other -6's flaps have the flaps hanging down like this?

rFhZ6DP.jpg

UVL0x0f.jpg

iDz395l.jpg
 
I did not build my rv6, but i am tweaking it for better speed. The flaps are rigged like the pictures and i am not sure if it is right. It looks like i am flying around with flaps out 2-3 degrees. This may explain some of the 5-8mph tas i am searching for. It has a 160hp 0-320 with catto 3 blade 67x70" prop. At 8000ft density altitude at WOT and leaned for max rpm, i am turning 2650 rpms doing 182.5 mph tas. The static rpm is 2200rpm, so i think the prop is correct, but the drag profile is too high. What are you guys thoughts on this flaps setup? I have not checked the incidence, but i have removed the wingtips and made a fixture to check the aileron and flap alignment to the chord using the tooling holes. It is perfect and the plane flies laser straight hands off. Do other -6's flaps have the flaps hanging down like this?
rFhZ6DP.jpg

UVL0x0f.jpg

iDz395l.jpg



I left my flap linkage adjusted so the flap was a few degrees too high/retracted. Then did a bunch of cruise testing in calm air to validate the most effective rectracted location.

In your case, you would need to remove the fences to accomplish that.

Larry
 
Tolerance seem to build up in that area during construction - no pre-punched stuff here...:)

Get a digital level and check that both wings are set at the correct incidence per the plans and then check the flaps are set at the same incidence measuring at the mid-span of each flap.

In my case I ended up with one flap slightly low like yours and one flap slightly higher than the bottom fuselage surface. A small extension inwards, bent as needed, on the flaps fixed the discrepancies, which were less than 1/8 inch.

Neutral for the flaps/ailerons is set by lining up all of the rib/aileron rib tooling holes at the wing tips. I could never get the plans recommended template to work correctly.


And apparently can even happen on pre-punched -7 kits... :)

http://www.vansairforce.com/community/showpost.php?p=1044286&postcount=11
 
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I could never get the plans recommended template to work correctly.

First let me apologize on resurrecting an ?old? thread, but it so happens that my -6 exhibits the same characteristics as titanhank?s.

A too long time ago, when I built the -4, I recall havin made the airfoil templates and rigged the ailerons and the flaps using them. As did the builder of my ship. Quite easy really, affix the templates to the still in jigs wing, drop said aileron or flap in, drill brackets. During final rigging place template on top of the wing and adjust flaps, ailerons and wing tips accordingly.

Same as titanhank, my ship has both flaps slightly extended in relation to the fuse, but perfectly in line with the ailerons and wingtip. One could rig the flaps fully retracted, then the ailerons to the flaps, finally the wingtips to the ailerons. All in the name of maybe a couple of knots more. On the other hand the profile would be modified, and reflexing flaps on this profile shows no benefits.

Since I can push on my flap handle and have the flaps ?fully? retract, I will do some inflight experimenting...

Titanhank, done anything on yours and care to share here?
Any comments from others?
 
First let me apologize on resurrecting an ?old? thread, but it so happens that my -6 exhibits the same characteristics as titanhank?s.

A too long time ago, when I built the -4, I recall havin made the airfoil templates and rigged the ailerons and the flaps using them. As did the builder of my ship. Quite easy really, affix the templates to the still in jigs wing, drop said aileron or flap in, drill brackets. During final rigging place template on top of the wing and adjust flaps, ailerons and wing tips accordingly.

Same as titanhank, my ship has both flaps slightly extended in relation to the fuse, but perfectly in line with the ailerons and wingtip. One could rig the flaps fully retracted, then the ailerons to the flaps, finally the wingtips to the ailerons. All in the name of maybe a couple of knots more. On the other hand the profile would be modified, and reflexing flaps on this profile shows no benefits.

Since I can push on my flap handle and have the flaps ?fully? retract, I will do some inflight experimenting...

Titanhank, done anything on yours and care to share here?
Any comments from others?

Don't assume that the fuselage is the correct shape in this area for the original kits that were not pre-punched.

The whole 'curvy thing' of the lower skin was very builder dependent with a lot of 'cut to fit'.

Check the wing incidence per the plans since that is the real reference for how your plane flies through the air as the designer intended.:)
 
Thanks Gil, good remark about the shape of the fuselage.
As to the wing incidence, I won?t check it since a/I assume it was more than correctly set by a meticulous professional builder and b/there ain?t much I could do about it and c/this -6 flies and performs beautifully as is.
As stated, I?ll be experimenting with going outta detent and moving/holding the flaps to fully up in flight and observe any effects it might have...
 
On my -6, the flap trailing edges are high by about 1/4". Basically, it comes down to the level of precision stackup between the plans, parts, and builder.

My philosophy there was that the wings were mounted and weren't going to move, and my job was to make sure the flaps and ailerons were rigged properly according to the airfoil template.
 
Interesting, so we are 2 down against 1 high ;)

I'm split, one slightly high and the other slightly low...:)

The other tolerance issue coming into play is the accuracy of the jigging, which isn't there on the later pre-punched models
 
I did experiment with raising the flaps to match the fuselage. It gained about 2 knots. I have put them back until i get time to really check all the angles. I have been occupied putting in a glass ifr panel and autopilot.
 
Gil, interestingly mine?s a pre-drilled, wings and tail, but the fuse still was the ?hard? way. I?m pretty sure that, even in this age of LEGO building, one can induce some differences by just holding or clamping pieces at an angle whilst pushing or pulling during the riveting operation.

Titanhank thanks for your feedback :cool:
 
I did experiment with raising the flaps to match the fuselage. It gained about 2 knots. I have put them back until i get time to really check all the angles. I have been occupied putting in a glass ifr panel and autopilot.

There is nothing wrong with flying with the flaps "reflexed" a couple of degrees.
Just do enough flight testing to see how it affects stall speed in all configurations. Shouldn't be enough to be noticeable.
 
ok, did a couple of flights experimenting with my -6: no discernible difference in speed by fully retracting the flaps.

I already noticed that said flaps set themselves up in a higher position whilst in flight, pressure on bottom and suction on top.
Now pushing the release knob on the flap handle and pushing the handle fully down shows maybe 1/2 knot speed decrease. The handle will then happily maintain that position.

Guess all ships being built with slight variations will show different results ;)
 
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