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RE: Bridi UFO Build (all wood) - 3/18/2006 1:46:49 PM   
rainedave



Posts: 4759
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		Thanks jlkonn! I didn't have any 2" x 2" balsa blocks so using Elmer's Carpenter's Glue I clamped up two 1" x 2" blocks. This actually worked out better since the glue seam gave me a visual centerline down the side of the block. I sanded all four faces smooth and traced the tip outline onto one face of each block. Then, using Super 77, I attached the planview pattern on the top faces. I used my scroll saw to make the planview cut first. Then I cut to the shape of the airfoil. It's a little tricky since the block no longer has a flat surface to rest on the saw. You just have to hold it tightly and pivot the block as you push it through the saw. At this point I glued the blocks onto the wing. I put masking tape around the wing right at the edge of the blocks for protection. Then, using a razor plane and 100 grit sandpaper I shaped the blocks. I didn't use templates to check the profile, I just went by eye. The two things I have to look out for are not removing enough material which gives the tip a bulged look from the front; and removing too much material which would create flat surfaces on the top and botom. The tip should have a gentle curve. I have to constantly look at it head on and stop using the razor plane when I'm between those two extremes. It can then be fine tuned with the sandpaper.

The stab parts are ready to glue up. It uses an interesting method with alignment spars that fit into notches in the ribs. I laminated the spars using a strip of 1/16" sheet sandwiched between the main spar material. The LE and TE rest on blocks and the whole thing is built suspened above the board.



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RE: Bridi UFO Build (all wood) - 3/18/2006 7:19:44 PM   
mmattockx


 

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quote:

I didn't have any 2" x 2" balsa blocks so using Elmer's Carpenter's Glue I clamped up two 1" x 2" blocks. This actually worked out better since the glue seam gave me a visual centerline down the side of the block.


I have an addition to this that I got from Dean Pappas, illustrious FM columnist (I think it was his, anyway). He suggested laminating two pieces of balsa, but sandwiching a piece of 1/32" ply cut to the plan view shape of tip, then shaping down to the ply, but not into it. This gives a nice centerline reference and a good hard point at the outer edge of the tip that prevents dings over time. If you also cut out the inside area of the ply it adds almost no weight and a good bit of functionality. The shaping part is still up to your eye, though...


Mark

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RE: Bridi UFO Build (all wood) - 3/19/2006 3:14:29 AM   
rainedave



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From: Greensboro, NC, USA
Status: offline 		mmattockx, that is a nice idea. I wish I had known about it. Oh well, I'll know to do it next time.

The stab halves are almost done. The elevators will be next. The plans show them made of 5/8" x 2 1/4" tapered sheet. That's a pretty big piece of balsa. I'm thinking it might be lighter to build them up and sheet them. It would be easier, too, than trying to plane a uniform bevel on a sheet that large. Something to think about.

Here are a few more pics of the stab halves.

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RE: Bridi UFO Build (all wood) - 3/19/2006 3:59:43 AM   
rainedave



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From: Greensboro, NC, USA
Status: offline 		Ok, here's a quick drawing of how the elevators could be made.

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RE: Bridi UFO Build (all wood) - 3/19/2006 4:13:57 AM   
mmattockx


 

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quote:

mmattockx, that is a nice idea. I wish I had known about it. Oh well, I'll know to do it next time.


Thank you, but the credit goes to Mr. Pappas.

I really liked your method of laminating the stab LE and TE to get the alignment tab. Excellent idea and one I will remember for my Dirty Birdy build.

quote:

Ok, here's a quick drawing of how the elevators could be made.


I could never bring myself to use that huge slab of balsa for a control surface. I would have to build them up, just to let me sleep at night. I agree with your layout, but I would skip the diagonal pieces and use 1/16" sheeting instead of the 1/8. That is just too heavy for anything but fuse sides, to my eye... I would probably skip sheeting it completely, though and simply frame them up with 1/4" sticks and leave it open bay for a film covering. I have looked at the ailerons on my Dirty Birdy plans and they even look too big to be solid and I will likely build them up if I go with a built up wing. I really like foam, though, so I may forsake tradition and do a sheeted foam core wing anyways. Ah well, decisions, decisions...


Mark

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RE: Bridi UFO Build (all wood) - 3/19/2006 12:53:35 PM   
8178



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quote:

ORIGINAL: rainedav

Ok, here's a quick drawing of how the elevators could be made.


Very nice work rainedav!

The rudder on my Tiporare was made that way and sheeted with 1/16” balsa. I added some solid balsa inside the frame at the bottom so I had a place to install the control studs. It is very light and has worked out well.

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RE: Bridi UFO Build (all wood) - 3/19/2006 2:26:57 PM   
rainedave



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From: Greensboro, NC, USA
Status: offline 		Thanks guys! Now that you say it, mmattockx, 1/8" is overkill. I've redrawn the elevators using 1/16" sheeting. 8178, I might just go ahead and build up the rudder as well using the same method.

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RE: Bridi UFO Build (all wood) - 3/19/2006 4:36:32 PM   
rainedave



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From: Greensboro, NC, USA
Status: offline 		I went ahead and whipped up a drawing for the rudder. I'll still use 1/2" sheet for the fin.

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< Message edited by rainedav -- 3/19/2006 4:39:25 PM >

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RE: Bridi UFO Build (all wood) - 3/19/2006 11:55:22 PM   
rainedave



Posts: 4759
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		The elevators were a snap, and I'm sure they weigh a lot less than the solid boards shown on the plans. I capped the ends with 1/32" sheet to make them look a bit neater.

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RE: Bridi UFO Build (all wood) - 3/20/2006 12:07:53 AM   
jlkonn



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Status: offline 		Dave...
Do you like do this professionally?

JLK


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RE: Bridi UFO Build (all wood) - 3/20/2006 12:37:31 AM   
roncoleman


 

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Status: offline 		Rainedav

My hat is off to you. You are one fast scratch builder. Outstanding
work also. I understand why JLK put the question to you.

< Message edited by roncoleman -- 3/20/2006 12:38:38 AM >

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RE: Bridi UFO Build (all wood) - 3/20/2006 3:39:48 PM   
rainedave



Posts: 4759
Joined: 7/21/2005
From: Greensboro, NC, USA
Status: offline 		Wow, thanks for the very nice comments, both of you. I've only built a few planes for other flyers and I have to say, it wasn't all that enjoyable. Besides, if one of my models blew apart in some outside maneuver, I'd feel somewhat responsible for any damage it might cause.

Since I was in the groove of building up the elevators, I went ahead and made the rudder. It is very light and extremely rigid. I used the drawing I posted above.

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RE: Bridi UFO Build (all wood) - 3/31/2006 9:44:00 PM   
rainedave



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From: Greensboro, NC, USA
Status: offline 		I've started work on the fuselage. The top block and sides are about ready to be glued together. The plans show two hefty, long hardwood engine mounting rails and they add a lot of rigidity to the front of the fuse. Since I'll be using a nylon engine mount on the firewall I decided to add conventional lite-ply side doublers from just behind the wing saddle to the nose. Everything else will be built according to the plans.

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RE: Bridi UFO Build (all wood) - 3/31/2006 11:12:09 PM   
Roary m


 

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