One Design - Bird Of Time Group Discussion

[Ed Anderson]

OK boys and girls, I am in.

I just placed my order for my BOT kit, covering and 2 digital servos. I have servos for the spoilers in my supply box.

I will use Monokote black on bottom of sheeted section of wings and the bottom of the fuselage. I will use Monokote white on top of the wings on the sheeted areas and top half of the fuse. Then I will use monokote transpartent red for the open bay areas.

I ordered dave brown carbon fiber stips to cap the spar. Based on what I have read I am not sure if I will warp the spar since the spar is capped by the sheeting. Will have to look at that more later.

I may enlarge the wing rod, or I may go to a 3 piece wing. I have not decided yet. Those would require design changes and since I am not much of a builder I will have to ponder these once I get the kit. I have links to discussions where these things have been done.

Last thing I am considering is making this one electric convertable. This would have a motor permanently monted in the nose, but would have a removeable nose block. Pull off the blades and attach the nose block to enclose and protect the motor for winch or hi-start launched fun. Just an idea. I will probably use a 280 watt motor I have on hand if I do this.

Now we will see if I can glue stuff together without making myself a permanent part of the plane.

[Ed Anderson]

If anyone else is interested in using this wing joiner method, you might find this note interesting. I have done business with www.hilaunch.com with excellent results.


From: Don Richmond - Hilaunch
Sent: Saturday, December 18, 2010 2:45 PM
Subject: Re: Wing tubes and aluminum joiner rod - some numbers

Ed,

The nominal wall thickness is .030 so you can add .060 to the basic dimension. .503 ID becomes .563 OD etc. Thicker wall are available in .010 graduations up to .050. i.e. a 7/16 (actually ..378 ID) would measure .478 with a .050 wall thickness but would be stiffer than a .503 ID tube at .030 wall thickness. A lot depends on what will fit. Of course a 9/16 (.563 ID, .6225 OD with .030 wall would be much stiffer.

So figure out what will fit and we can go from there. Tubes are 30 inches long and rods can be most any length and dihedral angle. If this is a regular BOT, I would not use less than a .503 ID, .563 OD tube if you are going to winch it. Also, IMHO, if you are going to cap the spar with carbon, use .014 on top under a balsa top cap. If the carbon is not sandwiched, it may buckle under load. I am sure you know that wings fail in the first 5-10 percent of the span and always in compression. The carbon tubes will flex a bit, but not break. I have not seen a broken CF tube in the 15 years I have been supplying them.

The Bubble Dancer has a .503 tube and .500 joiner, both supplied by me. If you like the way it works then it is easy to duplicate.

I don't know what the BoT kit looks like, but several people have built models by sandwiching the ribs between two pieces of ply or hardwood and drilling a hole for the tube through all the ribs in one stroke. The end pieces keep the ribs from splintering. The ribs are then slid onto the tube and CA'd in place. The Rogue 2M (from Ed Whyte) was built this way and can take a full pedal winch launch in a 20 mph wind. As far as I know, none have failed. The BoT kit may or may not permit this operation.

I am ordering some tubes and rods for stock, but do not expect delivery until the first week in January. I should have enough to cover your needs.

Don Richmond

[Ed Anderson]

ANOTHER BOT BUILD THREAD - 3 piece wing

I don't think this one has been listed, but even if it has is won't hurt to list it again.
www.rcgroups.com/forums/showthread.php?t=140856

This is a build done by schrederman, Jack Womack. It includes some good detail on how he made the solid center section and plug in tips. He calls his BOT winch proof. If Jack says it is winchproof, I believe him. His all up weight was 44 oz.

In post 7 he describes how he made the spars and a bolt on solid center section, a particular area of interest to me.
www.rcgroups.com/forums/showp...16&postcount=7

He comments that if you reinforce the wing and expect to do some stronger winch launches you need to replace the 1/4" center rod. He did not use it at all.

Even though this short build thread if from 2003, the year I started flying my Aerobird and my Spirit, it is just as valueable today as it was then.

[whatgoesup]

The One Design Contest has been held, July 24, 2011. The results and some pictures are here. www.rcgroups.com/forums/showthread.php?t=1331363&page=49#post18977758. Just scroll down to the bottom of the page.

[Ed Anderson]

This turned into a HUGE discussion on RC Groups
www.rcgroups.com/forums/showthread.php?t=1331363&highlight=LISF