RE: Bridi UFO Build (all wood) (Full Version)

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

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.




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

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



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

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.



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

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



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

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...[:D]


Mark



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


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.



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

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.



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

I went ahead and whipped up a drawing for the rudder. I'll still use 1/2" sheet for the fin.



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

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.



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

Dave...
Do you like do this professionally?
[sm=thumbup.gif]
JLK



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

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.



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

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.



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

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.



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

I want to say thank you for your post with the shots; I just got a set of plans and you give good clarity with regards to the subtle stuff. The plans are really good, but photos make a better visual. Did you mention the engine for him?



8178 -> RE: Bridi UFO Build (all wood) (3/31/2006 11:12:57 PM)

Very nice! Don’t you love it when a plan comes together!



rainedave -> RE: Bridi UFO Build (all wood) (3/31/2006 11:32:24 PM)

It really is 8178; after hours of studying every detail of the plans it's great to start seeing things take shape. Thanks.

Roary m, an interesting thing happened. The plans say to glue 3/8" triangle stock along the edges of the top block and then glue the sides to the tri-stock. I didn't like that since it didn't provide enough wood for the joint and for the shaping later on. So, instead, I used 3/8" square stringers down both sides of the top block. Well, I just got an email last night with a scan of the construction article - thanks Mark! - and in it, the author recommends using 3/8" square instead of the tri-stock for the very same reason! I had to laugh, since he felt the need to make the change, too, 29 years ago. Here's a scan of what I'm talking about. The red text indicates the problem area that was changed.



Roary m -> RE: Bridi UFO Build (all wood) (3/31/2006 11:55:13 PM)

I recieved a construction article with the plans and the 3/8 fuse stringers appear to be about the only really unusual detail to contend with. I was actually trying to figure ou how to fabricate the 3/8 quadrilateral stock, perhaps by jigging it through the band saw but it looks like I'll just go with the stock. After using a manual planer all these years, I broke down and got one of those g.p. power planer jobs. It works pretty good, so I will just give it a run here.



rainedave -> RE: Bridi UFO Build (all wood) (4/1/2006 1:17:20 AM)

I you wanted to go to the trouble, you could chamfer the 3/8" square stock like in the drawing below. Since I built up the rudder and elevators I've lost some tail weight anyway, so it just didn't seem worth doing.

What are you going to use for a canopy?



Jim_Purcha -> RE: Bridi UFO Build (all wood) (4/1/2006 12:38:51 PM)

Tower has a canopy from Great Planes which appears to match up the Dirty Birdy.

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXJ932&P=0

I could sent some additional photos. I just received two of these last week.



rainedave -> RE: Bridi UFO Build (all wood) (4/2/2006 3:01:20 AM)

Thanks, jpurcha. I looked at that canopy along with the Wing Mfg. offering. Both are shorter than what is shown on the plans, the WM being a bit longer. I've made a few plastic parts for FF planes by heating ABS in the oven and pulling it by hand down over a plug using a heat gun. It takes at least four hands and doesn't give the best results.

I've glued the back portion of the fuselage sides to the top block. It's time to put in a hardware order since I can't really work any further without the engine mount, fuel tank and nose retract. While I'm getting that together I can work on fitting the stab to the fuse and glue up the fin. Since the fuse still sits upside-down flat on the building board, it will be easier to adjust the anhedral stab to get it squared up at this stage (the tips will point up in the air).

I can't wait to attack this thing with the razor plane and 80 grit! ...you think that pile of shavings in the other photo was big?

The third photo attempts to show the seam in the side and the 1/32" aircraft ply scabs.



Roary m -> RE: Bridi UFO Build (all wood) (4/3/2006 6:51:54 AM)

The canopy from is a g.p. part # gpmq2110. I got some of these guys from tower awhile back and compared them to an original from a bridi dirty birdy kit I still have and both are identical. The canopy is 17 3/4" long and has the trademark divit along the periphery, very cool. I dont know why they still carry this type and not for the ultra sports because neither kit is being run. While I am on this thread maybe I could indulge the readers here as it relates to this old D.B. kit that I still have. Should I just build it or should I let it sit as a collector's item? I dont collect planes for the sake of having a collection, it just happens this guy has been sitting here forever. If the hidden hand takes it in flight, oh well, but I wasnt sure if that was the proper perspective to have on old stuff like this. My feeling is either they will build an arf or I will scratch one, but I'll take feedback, thanks.



Jim_Purcha -> RE: Bridi UFO Build (all wood) (4/3/2006 12:50:39 PM)

Build it.



SteveW -> RE: Bridi UFO Build (all wood) (4/3/2006 9:57:45 PM)

quote:

ORIGINAL: Roary m

While I am on this thread maybe I could indulge the readers here as it relates to this old D.B. kit that I still have. Should I just build it or should I let it sit as a collector's item? I dont collect planes for the sake of having a collection, it just happens this guy has been sitting here forever.


They are still available: http://www.bridiairplanes.com/hangar/dirtybirdy60.html

Build it and enjoy! [:D]



rainedave -> RE: Bridi UFO Build (all wood) (4/5/2006 5:20:49 AM)

Ok, I'm calling on all the experts around here, I have a dilemma.

I'm getting ready to order pneumatic retracts. I can't decide whether to go with a firewall-mounted nose gear or rail-mounted. I vectorized part of the plans so I could play around with the placement and both have their own unique problems.

The first pic shows the rail-mount setup. If I go this route, the 1/4" ply rails (blue lines) will interfere with the fuel tank space. The dotted lines show the tank. A solution would be to go with a smaller flexible tank and squeeze it in.

The second pic shows the firewall setup. This eliminates the fuel tank space issue, but the retract mounting bolts would be very close to the bottom corners of the ply firewall. The green line shows where the bolt would be and the blue lines are the firewall. A solution might be to cut a new firewall that extends down a bit further. Since the fuselage belly is a balsas block, there is room to extend the firewall down.

The third pic shows my firewall (upside-down) and the red crosses are where the retract bolts would go - obviously, I'll need to cut the engine mount bolts and glue another piece of ply over the blind nuts. Do you think the bolts are too close to the corners to be strong enough? I'm concerned that they could split out that close to the edges. Right now, I'm leaning towards cutting a new firewall about 1/4" larger around those corners, but maybe it would be strong enough as is.

What would you do? Rail-mount or firewall-mount? I'm open to suggestions.



Paternguy -> RE: Bridi UFO Build (all wood) (4/5/2006 9:07:31 AM)

On mine I went with the firewall mount. I added an additional 1/4 piece of ply to the back of the firewall and counter-sunk all the blind nuts and cut off the excess screw thread, to avoid any interference with the motor mount. over 10 years i never had the screws split out of the ply.



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