Micro UFO Build Thread - Page 2 - RC Groups
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Jan 21, 2012, 03:22 PM
AndyKunz's Avatar
Originally Posted by Pitstop000
Here you go Andy

Attachment 4549404
Got a bottom view like that?

I'm building again today. I'll be posting photos later.

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Jan 21, 2012, 06:58 PM
AndyKunz's Avatar
The forward fuse is sheet. I attached it to the spruce frame built earlier. I didn't have any 3/16 or 1/4 triangle, so I used 3/16 square for the corner stock. Much of this will be sanded away when we get to rounding the nose off.

The fuselage formers are hard 3/32" balsa but the firewall is 1/16" ply, just like the rest of the micros I've been building. The wing ribs are hard 1/32" (they will be lightened a little later on).
Jan 21, 2012, 07:06 PM
AndyKunz's Avatar
The top side is going to be done with stringers. To get a nice transition to the cowl hatch (which will be hollowed balsa block) there is a partial former that the stringers will be resting on.

The nose wheel mount is just a hard block again, as I showed in the Bridi trainer build thread a few weeks ago. The free castering is adequate for control on the ground. I had a time getting my full-size fingers into the micro T-20 nose to lock the setscrew, so this time I brought the hole through the firewall.

It sure is fun to build these little guys. I really encourage you all to try. Use the plans for something you already have, get a sheet of 1/32" balsa and pull the scrap box close and dig in!
Jan 21, 2012, 10:01 PM
AndyKunz's Avatar
After cutting some lightening holes in the ribs, they were separated in preparation for building the wings. The blocks for the main gear are made from 1/4" sq hard balsa. I had to cut a notch in them using the razor saw to allow the wire to fit snugly inside.

It doesn't look like much, but these photos show how I spent most of my afternoon. These steps were done while the fuselage formers were installed. The next steps will be to finish joining the rear half, make a mount for the receiver brick, and make formers for gluing the stringers in.
Jan 28, 2012, 04:51 PM
AndyKunz's Avatar
The left wing panel is framed up. I built it upside down on the plans. When doing this I had to make sure that I had the ribs oriented properly for the landing gear block, and had to angle the root rib properly.

While the wing was drying, I was able to join the tail of the fuselage. Be careful to use centering marks on the formers near the nose so that the tail is straight. The sides then have short cross-pieces inserted between them to round out the taper per the plans.

There was also time to start on the stab. These are built up, but if you notice the ribs are just 3/8" high rectangles right now. This make them much easier to build. The LE and TE are 3/16" sq lifted 3/32" above the plans, centering them on the LE and TE. I will sand the whole thing to an airfoil later on.
Jan 28, 2012, 06:19 PM
Registered User
Mendo's Avatar
Looks Great Andy!
Jan 28, 2012, 07:11 PM
UFO Driver
R_G's Avatar
Very Nice! This is going to be neat little model!

Jan 28, 2012, 07:31 PM
AndyKunz's Avatar

It's certainly the slowest micro build I've ever done.

Jan 28, 2012, 09:30 PM
AndyKunz's Avatar
After building the second stab, I started on the fin. The plans show this as sheet, but I'm building it up to reduce weight.

The TE of the rudder is made by laminating a 1/64" ply strip between two sheets of 1/32 balsa. This makes the TE stronger to prevent damage and bowing when the covering is shrunk, but also provides a reference for sanding. I'll use the same technique for the elevators.
Feb 02, 2012, 10:41 PM
AndyKunz's Avatar
The elevator halves are built-up too. The LE and root are 3/16", and the TE is the same construction as the rudder TE. We need a little beef here to handle the control horn and not twist. Also, the LE will be cut back on one side for hinging.

The fin LE is curved, so I cut that to shape and then rounded it and tapered the sides into it. The result, one the rudder is attached, will be a gentle diamond with 1/8" thick LE and 1/16" TE and 3/16" thick at the hinge.

I plan to use hinges on the centerline of the rudder, but I'm still debating whether to use covering hinges on the elevator or the same type as the fin. Anybody got suggestions?
Feb 03, 2012, 09:40 AM
Registered User
bpink43's Avatar
Andy, I have used the regular CA hinges that I cut to very narrow strips in my micro tiporare build.....which i need to get working on again, but they seem to work ok. However, I think I would go with the covering hinges as even with the trimmed down CA hinges, the little ultra micro linear servos have a bit of strain to deflect my ailerons.
Feb 03, 2012, 06:19 PM
AndyKunz's Avatar
CA is definitely a bad idea, I was thinking of using mylar like we have with the actuator-based RC systems. Thread hinges were gone by the time this came around.

Feb 11, 2012, 03:25 PM
AndyKunz's Avatar
It's been a busy week, and none of it was for building airplanes. But that's behind me for a few days, so I got to do a little more.

The wing tips were cut from a soft block I had in the scrap bin. The are slightly oversize, glued on for finishing.

After sanding to an airfoil shape, the center line at the tip is marked for reference when carving and sanding. The sanded wingtips are ready to be hollowed out later.
Feb 11, 2012, 03:29 PM
AndyKunz's Avatar
The stab tips get the same treatment, except that the ribs are sanded to an airfoil instead of serving as an airfoil reference.

The stab is finished while the elevator is attached. The elevator was already tapered in earlier steps, and serves to make sure we keep the shape proper. I have not angled the elevator LE yet because I wanted it square for this operation.

Got to get back to doing some building now.
Feb 11, 2012, 08:32 PM
AndyKunz's Avatar

Mounting the stabilizer on the fuselage would be a little difficult with the unsheeted stab and open frame construction. I changed the tail a bit by insetting balsa sheet into the spruce frame on the sides and bottom. Next I removed the root ribs from the stab and used them as patterns to set the incidence (0) on the new sheeted tail.

The solid root of the stab will be lightened. I only need about 1/8" for the covering to be attached well, and it doesn't need to be solid, but this makes it a little easier for construction.

Right now the wings are hanging up in front of the shop heater, drying the servo rails. Hopefully it doesn't take a week for me to work on this again!

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