Hello,

I have bought recenty a Boomerang XLII which has been glassed and painted. Unfortunatelly, flaps have not been hinged properly to be able to open at 90 degrees as same is recommended for this plane to prevent floating while using crow braking!!!

I know that hinges are supposed to go on bottom surface but edge of flap has been cut and hinge installed in centerline. Could anyone advise how to modify hinge installation without messing painted surfaces??

Thanks in advance for your help.

Regards,

I would suggest that you cut through the old hinges and install some Robart pin hinges, the flaps are useless as they are as you are aware,
Gary.

madmodelman,

The old hinges are all on a single piano wire and therefore easily removable. The problem is that surfaces are now beveled from both sides and if i install hinges in the lower surface, there will not be enough wood material to hold center part of hinge. However, don't know if the Robart pin hinges will do the tric....

Well you will need to install a triangle of material to fill the triangular gap that has been made at the lower surface. I would use hard balsa, carefully sanded and shape to make a good fit. Then move the hinges to the lower surfcaes. The problem is the colour match. The balsa will need to be covered with the same film covering as is currently on the wing, and I would cover this before the hingng process. If you can't get nmatching film, go for a contrasting colour.
Well worth doing on this model. good luck with it.
John

John, its not film its a painted surface, stub wing, only the outer panels are filmed.
There is no need to reshape any surfaces if the robart holes are drilled at the correct angles and heights.

I understand what you are saying, the Robarts are very long, if you feel they protrude too far out of the wing t/edge just use some brass tubing for support.

Yes, I was just taking another look at the pics again when I realised it was a composite structure. You could do it with extended robart hinges, and it would work, but I would not want the ugly gap left there.

Would reversing the flaps help with the angles? put left on right etc, you will obviously have to recover them and reverse the horns.

I can't see for the life of me what the problem is, there has to be a gap somewhere, the hinge holes need to be as low as possible and angled up into the surfaces so they don't break through the surface, it's a five minute job!

Thanks Gary,

You have a very good point using the brass extensions if needed and forget about the Gap. Thank you all for taking the time to look into this.

Regards,

Like below Gary with the hinge on the bottom surface, snag is I think he has too much of a bevel unless he adds a bit of triangle stock in and covers it.

You will also need to put the flap control horn on backwards or you won't have enough leverage to pull the flap 90 degrees.

I just learned a lot about flaps.

Keith

I would use this ones to fix that.

Simple, clean and strong.

http://dreamworksrc.com/catalog/offs...rt-p-1010.html

They look very much like JetLegend ones, very good and you can remove the control surfaces as well.

Yes, you can do that also you can reverse them to get maximun travel, use the horne that you have and cut the one from the hinge.

Every one has them, they all come from the same place ( China )

I agree with swaping the sides and recovering.  Then you will have your 90 degrees and no triangular gap on the top when not extended.

Thanks again for all input. Reversing the flaps was indeed one of the options but aspreviously said XL was bought already glassed and painted. In fact builder has done the mistake to install the flaps reversed in the first place.... i guess it would be a hassle to repaint the two surfaces as i do not have the proper equipment.
As for the CF hingesm wouldn't it be a problem to have flaps offset when lowered leaving a gap between wing panel and flap?? From what i know, this kind of hinges works best when moving surfaces uner an overlaping edge over the moving surface!!!

Regards,

No, they work fine like that, they are called slotted flaps & are very common on large full size jets.

I have them set up like that on a Top Flite P-47 & a large sport jet/trainer.

Mine are set up with Robart hinge points. - John.

You have two good options presented to you - either use the offset hinges that CARSII suggested, or use the Robart Hinge points (the BIG ones) supported by brass tubing where they hang out of the wood, as madmodelman suggested. Take a look at both and use the one that you think would work the best. I would mount the hinges such that there is no gap when the flaps are all the way up and don't worry about the gap when they are down. If anything, the air flowing through the gap when the flaps are down will be turbulent and give you more drag - which is what you want on a Boomerang. You don't need the flaps for extra lift...

Bob

You can buy hinge pockets for the Robart pin hinges that allow the hinges to be removed, I don't know how good an idea that would be, but on my Elan I drilled a hole in the end of the stub wing to allow Hysol to be applied around the pin hinges internally.

Mike

What happened here is that at the factory, they reversed the flaps when they covered them
the bevel is sopposed to be at the bottom
you can do this:
1. Communicate with Boomerang jets and get a pair of properly covered flaps and replace them
these should have the bevel at the bottom!!!!!
2. Keeping the same flaps, cut a bevel into the bottom rear photo as depicted in the picture, then
fabricate a hard balsa or hardwood filler and fill in the area between the lower flap surface and the front of the
flap LE to maintain strength. This will allow the flaps to lower properly to the recommended throw listed in the manual</p>

The Flaps aren't hinges at the factory, you have to attach them yourself, also if you read the first post he bought the airframe from someone else.

Mike

and the wings are painted not covered

In the first post he say's glassed and painted.

Mike