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Andrew Cousins18/04/2018 20:37:36
153 forum posts
20 photos

Hello balsa bashers I need a bit of help.

Ok I am building a TFcorsair 60 size. I have never built a plane with flaps before and I am this stage with the build process. I have followed the instructions and am now fitting the Robart hinges and flaps into the wing. I have sanded the flaps to the correct profile as per the plan and the 1/16 ply side plate that fit to the flaps. The problem i now have is that the flaps seem to be two thick. The LE of the flaps is much bigger than the TE of the wing.

Now the instructions say that material should be removed from the TE of the wing to form a socket for the flap LE to fit into. I get this but my concern is that if i do this i will have a large amount of flap sticking above the TE of the wing on the bottom.

Now i assume as i have not fitted flaps to a wing before that they should follow the profile of the wing when NOT deployed, both top and bottom?? am i correct in say this.

If i am and the solution is to remove a large amount of balsa of the flaps im in a bit of trouble. It will be fine for the inner and outer flaps as they are solid blocks (aileron stock) but the center flap is built up and to remove this much material will basically take the complete bottom off the flap.

Any advice would be of great help and much appreciated.

Many Thanks

Jon - Laser Engines18/04/2018 21:01:45
3914 forum posts
151 photos

can you shoot us a photo Andrew? I'm just trying to visualise the problem.

As a side note, the TF corsair is known for being tipstally at high angles of attack, even at high speed. I recommend a good amount of flap deflection for landing and a gentle curved approach with a reasonable amount of speed on. Try to keep a constant rate of decent and don't let the nose rise. Use the lowest elevator rates you can get away with and lay off the expo. Keeping the model as light as you can will also help a great deal.

Levanter18/04/2018 21:28:07
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744 forum posts
366 photos

Andrew

​I think I know what you mean but like Jon says, a photo or two would really help.
​My Grumpy Tigercub is at the flap stage so this is topical for me.

Levanter

Ian Mat18/04/2018 21:30:21
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121 forum posts
39 photos

Jon, I'm surprised that you found the TF corsair tipstally... mine flies like a trainer... I've yet to find any vices!

Andrew, when the flaps are installed there should be a clean line from the leading edge of the wing, to the trailing edge of the flap. You may need to sand the flaps down to achieve this. Looked at in cross section the flap should follow the natural curves of the rest of the wing.

For what my opinion is worth, I would avoid the robart retracts and fit eflite electric twist and turns, unless you are flying from tarmac and are supremely confident in you lading ability!

Andrew Cousins19/04/2018 19:39:06
153 forum posts
20 photos

Hi guys right i have taken some photos for you ok here we go.

4.jpg Right first i thought i would show you what the instructions tell you to do with the TE of the wing. Basically you remove 3/16 in from the rear of the TE of the wing BOTTOM only. You then sand a curve into the TE leaving a over hang on the top of the wing. This over hang will cover the top of the flaps. The instructions then tell you to mark and drill holes 4/16 up from the bottom of the wing but from the bottom of the 1/16 sheeting that is glued to the TE not the exposed sheeting on the bottom of the wing. If that makes sense or you could measure 5/16 from the bottom of the wing would have been a better explanation.

So hinge holes marked 5/16 from the bottom of the wing, Holes drilled. robart hinges inserted. Now what i did was to fold the hinges over 90 deg, then offer up the flaps to the wing and ensured that the top of the flaps lined up just below the 1/16 sheeting on the top of the wing. This is wear the over hang will be. I then pressed the flap into the hinges to mark their positions. Holes then drilled into the flaps. photo showing top flap below.

1.jpg

As you can see the flap is slightly lower than the top wing sheeting FAB. But take a look at the bottom of the wing.

3.jpg

like i said in my original post not to worried about the two outer flaps as they are solid. But the inner flap is built up and to take off this much material well it wont be good.

Guys i hope this helps and appreciate your input

Many thanks

Andy C

Jon - Laser Engines19/04/2018 20:55:08
3914 forum posts
151 photos
Posted by Ian Mat on 18/04/2018 21:30:21:

Jon, I'm surprised that you found the TF corsair tipstally... mine flies like a trainer... I've yet to find any vices!

Andrew, when the flaps are installed there should be a clean line from the leading edge of the wing, to the trailing edge of the flap. You may need to sand the flaps down to achieve this. Looked at in cross section the flap should follow the natural curves of the rest of the wing.

For what my opinion is worth, I would avoid the robart retracts and fit eflite electric twist and turns, unless you are flying from tarmac and are supremely confident in you lading ability!

In fairness I have never flown one but I have heard loads of people mention that it was a bit animal. If they are wrong then I'm happy to hear it, but thought I would recommend caution in case they were right.

you are spot on about the retracts though. I had a set in a P40 and I had them fold up just taxiing out to the runway!

Andy, that looks rather odd. It essentially looks like the flap leading edge is simply too thick. Not sure how that could have happened. I would probably just make it match the wing

alex nicol19/04/2018 21:06:54
106 forum posts

Bit of a pain, but I agree with the others, time for the sanding block and make the flaps fit

David Ovenden20/04/2018 01:20:46
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323 forum posts
16 photos

I have not built one of these so have no personal experience to offer. However, I found the manual online (I think) **LINK**

Page 31/32 seems to suggest that the flaps are built as part of the wing and then separated after sheeting them. So I would have thought the flaps should end up with the correct profile for the wing section. It suggests that the flap LE sheet (part A )may need to be tapered to fit. Possibly you had an oversized part in your kit?

Andrew Cousins20/04/2018 10:57:10
153 forum posts
20 photos

David. the manual asks you to tack the parts the the TE so they can be removed after. If you build them as the instructions ask (which i did) They are very close to the wing profile. BUT when you drill the holes in the TE as per the instructions and then fit the flaps to sit in the socket, you have a over hang on the bottom of the wing.

Now i have built them i would have done it differently. I think i would have taken into account the depth of the over hang and built the flaps this much smaller. Then when they were removed and offered up to the socket they would have been very close. We live and learn.

As previously mentioned not a problem with the two solid flaps. Plenty of sanding will sort these, but i can see me having to build my own middle flap.

Guys you have me worried about the retracts. I have a set of eflite twist and turn retracts. How long ago did you have issues with these retracts. I hope it was a while ago and they have improved the quality!!

Ian Mat20/04/2018 12:34:27
avatar
121 forum posts
39 photos

Andrew, The eflite electric retracts are fine, its the robart pneumatic retracts that are no good, they're way too flimsy.

I would highly recommend fitting some type of spring loaded oleos to the retract units, they will prolong the life of your undercarriage.

Also make sure you building it as light as possible, you should get away with not having to add lead, if you're prepared to fit the flight batteries in the cowl, which is what I did, instead of fitting nearly a pound of lead!!!

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