Feb 14, 2010, 08:21 PM
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Austin, Texas
Joined Aug 2009
33 Posts
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Blast From the Past with a 1/2a Bee-tween
The Find:
I guess this qualifies as a mini-review, 20 years late. I recently picked up an old plane at a swap meet. I didn't know what it was, it just looked cool, and the guy took $20, what the heck. A little research and I found it is a Randy Randolph Bee-tween. It was meant to fly on two channels with a 1/2a glow engine.
E-Conversion:
The plane was super clean, and looked like it had never been flown. I didn't see any signs of glow fuel residue. There was damage, but it looked like damage from years of neglect and storage. I ended up completely stripping down the fuse to bare balsa. I used a heat gun to remove the film and then lots of sanding to remove the remnants of color. I re-covered in blue and added white stripes to the tail. I think it looks kinda like a PT-19!
I also added a very small tail wheel. I was careful not to add much weight to the tail. This plane was designed for a pretty heavy engine in the nose. An outrunner would no doubt be lighter.
Next came two fresh HS-55 servos, a Spectrum sport receiver, 18 amp ESC and 3s lipo (11.1V). The motor is a Rimfire 28-26-1600Kv turning a 7x5 prop. According to the datasheet, the combo is good for 180+ watts (overkill).
The motor mount was easy as there was already a heavy ply firewall. I just drilled holes for standoffs in the right hole pattern. Fishing the screws in from behind to hold the standoffs was the hardest part. I put epoxy over the screws to make the standoffs permanent.
The battery tray was also pretty simple. The rails that hold the servo tray continued all the way to the nose. I just added another tray of ply for the battery and one for my receiver.
Weight balance required 14 grams of dead weight on the firewall, even with the battery shoved all the way forward. Not bad. I balances right on the main spar. The all up weight is just a hair over 1 lb.
Flight:
In short, this is the most fun I've ever had on 3 channels! What a nimble, fast and fun little plane. The combination of small, light plane and small fast turning prop is a blast. It accelerates just fine, will go straight up, and will go FAST! Despite it's speed, it WILL slow down. You just have to give it some time. In fact, you can almost hover in a 5-10 mph wind. This is a hands-down fantastic little plane for park flying!
I knew I was overkill on power, but I was having so much fun on the first flight I couldn't hold back...then pop....what was that! Was it a rubber band....nope the wing! The main spar cracked in a tight fast (ahem...full-throttle) turn
I was lucky the wing failed gracefully. The plane actually still flew fine. I didn't really see what was wrong until I was home looking closely. The main spar is balsa. It has ply doublers, but only in the very center section. The balsa snapped at the stress-riser where the ply stopped on the right side.
I repaired the break and then extended the doublers out one more section of the wing in both directions. I patched my holes with black stripes and continued the pattern across the wing. Patch, what patch. I like the under-wing stripes. It looks fantastic in the air!
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