Vixen Flaperon Update and Another Flaperon Question

[n85ae]

I have a pair of Tatco hand squeezers, and a nice ATS rivet gun, but would concur with this idea of using modified vice grips.
The principal is the same and for the flaperon trailing edge it would work perfectly.

Jeff

I definitely think solid rivets look much better on the flaperon trailing edge. A solid rivet squeezer would be nice, but rarely used elsewhere. I just used a pair of vice grips with the jaws ground flat; worked great.

[Delta Whisky]

Tim - this input might be too late but since we are all here to help each other spend lots of money I would recommend using a vixen file.

Here's one on a palm block: https://www.yardstore.com/vixen-file-on-palm-block

And, as a full file: https://www.yardstore.com/10-single-...file-with-tang. (I don't recommend the double cut version.)

Once used, you'll wonder how you ever got along without one.

[tim.green]

Thanks for the great input everyone. I have another question: We're talking about flush rivets, right? Doesn't this require countersinking or dimpling to make them flush? If so - how would you dimple with anything but a squeezer with the correct dimple die?

Also - thanks DW! That Vixen file looks cool and I'm building a Vixen!

[jiott]

Very careful use of a countersink bit will do the trick. Getting the rivets totally flush is not really necessary. Of course use a dimpling tool if you have one.

[CoClimber]

I've attached a photo of the top and bottom of my rivets that I set with my knipex pliers. I'm not sure how well dimpling would work on such thin metal, but I'm not an aluminum airplane builder.

[Dave S]

CoClimber - rivet work looks good. I do like what folks have done with the solid rivets - although both types work fine - much nicer than the pop rivets.

Regarding "I'm not sure how well dimpling would work on such thin metal" the answer is not very well....

FWIW - if the concern folks have is about areodynamics/drag - the rivets are such as small contributor to drag on the kitfox flaperons it is totally irrelevant.

[Delta Whisky]

The rule of thumb: dimple if less than 0.030 inches thick; countersink if greater than 0.030. On my flaps, the factory used round head solids as did I when mounting the counterweights. Since the shop head will stand proud, as will the backside of the dimple, and because a 3/32 diameter rivet head is so small, to me it doesn't make much sense to go to the extra effort of countersinking. Just my $0.02.

[CoClimber]

It would be fun to calculate the drag from those rivets but I agree that it is probably irrelevant. I did do some calculations for unstreamlined wing struts. I believe that I calculated that at 100mph, it takes 22HP to push them through the air. Well streamlined, it takes less than 2HP, assuming my formulas are correct. This was based on an article I read in the EAA a while back.

[jrevens]

The rule of thumb: dimple if less than 0.030 inches thick; countersink if greater than 0.030. On my flaps, the factory used round head solids as did I when mounting the counterweights. Since the shop head will stand proud, as will the backside of the dimple, and because a 3/32 diameter rivet head is so small, to me it doesn't make much sense to go to the extra effort of countersinking. Just my $0.02.

I concur with this. Having done a lot of metal aircraft work, I’ve been taught that you don’t countersink material as thin as the flaperon skins, which I believe are 0.016”. That thickness is less than the height of the head of an AN426 3/32” rivet which requires a 100 deg. countersink. Common pulled rivets would be a little bit better since they normally have a 120 deg. head, but still not good. If you dimple in this instance, you’re dimpling a bonded joint and damaging it at that point. Probably not a big deal, but you are. I personally like the look of the standard AN470 rivets for this. Being at the trailing edge of the structure especially, the drag is inconsequential. There is nothing directly behind the tiny amount of disruption to be affected aerodynamically.

[tim.green]

Thanks everyone and thanks for the pictures CoClimber. Thanks also for your patience as I'm new to all of this (never had to rivet any of the RC airplanes I built!). Two more questions:

- Setting an AN470 rivet with Knipex pliers - any special technique? Just squeeze it until the shop head is the correct height / width?

- Streamlined wing struts: I've been considering these but they are expensive. KF sells a streamlining kit but they caution that struts streamlined with the kit are prone to damage b/c it's a common push point. Are the streamlined struts worth the $$$?

Really appreciate the help everyone!