Aileron counterweights

[n3480h1]

If we locate the weight internally in the wing, we risk limiting aileron range of movement, or even hitting the inside of the wing skin. If we locate it in a sectioned part of the wingtip trailing edge we add drag with every aileron deflection. It occured to me that I could mount the weight on a tube welded or crossbolted to the outer section of the aileron torque tube. Projecting forward, it would be located to either side of the aft end of the pilot's seat, between the seat and the side of the fuselage. The weight would perform the same function as a wingtip weight, it just does its thing on the inboard end of the wing, via the aileron connecting pin. Obviously, there would need to be something constructed around this area to prevent any stray objects from getting in the way of the weight's movement.

I contacted an aircraft designer about this. His suggestion was to use two (or more?) weights working internally in the wing, allowing smaller weights, greater deflection range, and avoiding the skin banging experience. This also eliminates any tortional loading in the aileron. Makes sense to me.

I'm still wrestling with the different concepts. I want it all - balanced ailerons, no draggy projections on the wing, a single piece wingtip, and ease of access to the weight in case small adjustments are required.


So, I'm looking for your comments. Which method do you like, and why?

Tom

 

[Schmleff]

I agree, the counterweights are perplexing, especially with the wing tips I built. It took me a long time to make sure there would be no binding of the counterweights.

If I were to do the counterweigts again, I would take a hard look at mounting them with a tube that is connected to the forward part of the aileron, the same surface that the hinge mounts to. With a straight tube, you shoiuld be able to run the tube into the wing without hitting the inboard surface of the skin.

That said, I personally am not really that concerned about a tiny amount of drag created by the counterweights in a turn. It is really quite insignificant. Unless you are pylon racing, you will spend most of your time straight and level. If you are turning that much, you are not likely on a cross county flight where you are hoping to optimize drag.

 

[n3480h1]

Good point about the drag issue, Jeff. I've thought I had all this figured out about four times now, but I don't have the final solution worked out yet. I like the two weight internal system concept, but I'll need to do a little modeling to see if internal range and clearance are issues - and I do not want an external rod fairing. I have received experienced and respected advice which tells me that having the weights attached directly to the aileron is a necessity to counteract flutter. And then some wiseguy (Scott) reminded me of Leeon Davis's DA-2A square tips - which opens up more possibilities. Even thought about spades. Maybe I'll come full circle and go back to the tip weights. I know I'll come to a resolution, but its not here just yet.

Tom

 

[n3480h1]

I looked at a friend's Thorpe today, which just happened to have the wings off. The counterweight is internal until the aileron is deflected up, and then the weight protrudes through a small opening in the bottom skin. This arrangement is located at the outboard end of the wing, just before the wingtip, and the wingtip remains in one piece. This is the system I will use. Problem solved.

Tom

 

[Schmleff]

Picts please

 

[n3480h1]

I'll see if I can get some tomorrow and post here, Jeff.

Tom

 

[phzabriskie]

Ok you've got my attention....worked on the plane today. Set flush rivets in the right spar. I had thought I would pursue Jeff's wingtips. Just curious Jeff, will there be a final film clip of your construction? If your counterweights Tom make the Hoerner Tips easier to do that would be very cool.

 

[o2koold]

Tom,
This sounds like the setup I will be using. My end aileron rib will be 4130 with a counter balance arm shaped like the one from T. Bingelis' book. It is not possible to make the whole thing contained inside the wing tip due to the height at the trailing edge. it will be set up that in up deflection the arm exits the bottom of the tip into a faired bump. My wingtips will have nut plates/flush screws to secure them give accesses.
Scott R

 

[n3480h1]

The heat index was non-lethal tonight, so I got out to the hangar and took pics of the Thorpe S-18 aileron counterbalance weight. The weight is bolted to a 3/8" square 4130 tube. When deflected full down, it stops about 1/8" from the top skin the inside skin. Deflected full up, the counterweight exits the bottom through a narrow opening in the bottom skin. The wings are off the Thorpe for repair/paint, so I cannot comment on stick travel.

Tom

 

[crcfi6303]

On my KR2 pcitured on my profile picture, the counter balance weight was mounted in the center just the same as the T-18. A small bump was faired in the lower surface of the wing, and then gap seals were applied to the lower surface (the aileron was top mounted with a piano style hinge its full length). These two attentions helped dramtically in climb as they were both exposed to the relative wind during the climb. No one reported much benefit in cruise, but 10 mph in climb at the same power settings, and same apparent pitch attitude (degrees).

A good source for using a design like Scott talked about is to get on the Cozy website or Velocity website, and see the style builders use there for their elevator balance, which as I understand it from Velocity is a tube style. When I visited the Sebastian Florida assembly plant for Velocity, that was the design they showed me on that one. A look at Mark Langford's website will also show a method of balancing the elevator from within the empennage (tail section), as opposed to trying to fit it on the elevator or between it and the hinge.

 

[Schmleff]

The thorp one pictured is kind of like what I was thinking accept that I would mount the tube to the hinged part and make the tube enter the wing straight from behind. That way the tube could be longer and get to a thicker section of the airfoil and also require less weight.

However, it might not be feasible. I would have to draw it.

 

[Raceair]

I have only seen the tip type counterweight, I know Monnett had a different counterweight in as later design, I just have never seen it.....You certainly wouldn't want to penetrate the rear spar anywhere. Thats why the aileron balance is usually at the tip, just outboard of the end of the C channel spar...going below the rear spar with a bent tube, that goes back up and into the wing where the lead weight would be, would cause probably more drag than the tip counterweight faired into the wingtip....Ed

 

[n3480h1]

Ed, as usual you make perfect sense. I had to consider all the options, but all the good points brought out by you and others here lead me right back to the tip weights. It was worth the effort to explore because I learned a lot about different counterbalance systems, but after all the considerations its hard to beat a proven - and uncomplicated - design.

Thanks to all for the help and good advice.

Tom

 

[Raceair]

Great....And Remember, If you make the counterweight arm a tad longer, it needs less lead to counterweigh the aileron, which can, in turn, make the whole system lighter. ...Ed

 

[Chuck in Indiana]

but after all the considerations its hard to beat a proven - and uncomplicated - design.

Where's that thumbs up emoticon? ;D IMHO, you're not going to make many significant improvements to the design. It is elegantly simple..

 

[n3480h1]

Very true, Chuck. But its just my nature to question, explore possibilites, and look for a better way. Really have to hand it to Monett, this is an efficient, attractive and fun amature built aircraft - and one that few can top. Glad I chose a Sonerai. Spent 8 happy hours today out at the hanger making the cooling plenums.

Tom