"Tribewt" maiden - Baby Blender monoplane hybrid.

by alibopo | June 4, 2013 | (7) Posted in Projects

Tribewt monoplane

19th April was when I finally got out to try a maiden on this plane - sorry no video! I didn't fancy juggling a video camera and flying the plane. Well, my 'Tribewt' – newly named -  just floated off the ground in what looked like a perfect balanced take-off. But no! It was tail heavy - and things soon went wrong. A drooping tail and excessive control throws on the ailerons soon had me beat. After a few wobbles and swoops I nosedived and pranged the propeller. The plane survived relatively unscathed as the foam nose absorbed a fair bit of the shock. Well I should have stopped there, but I put on another prop, adjusted the elevator trim to try and compensate for the heavy tail and took-off again. Well, it flew, sort-of, but (!!! because I didn’t take time to check properly !!!) the last crash had loosened the elevator horn. Soon it had worked loose and I was struggling to get any reaction from the elevator. The plane climbed to a dead stop, did a back flip and plunged straight down for another dirt nap. I wiped out the front end, but the motor and pod survived! I did a field repair, hence the packing tape on the nose, but I couldn't repair the control horn - which was probably just as well - who knows what the next crash would have wrecked!

When I got home I rebuilt the nose, losing some of the fancy detail,

and took the opportunity to shift the wing back about 15mm.

I also fixed and reinforced the control horn,

I know it looks a bit askew but it's screwed through into the lolipop stick underneath so its solid.

Second outing was Sunday 2nd June. You’ll see from the film that it flew pretty well, though I felt it was still a tiny bit tail heavy.

First flight ended in some kind of brown-out, and the plane did a nasty belly flop. Fortunately nothing was broken. I swapped-in another battery and this time I hand launched. Once it was trimmed-out it was great fun.I was quite happy just looping it around the field. The landing was a bit rough again, but I reckoned with better balance it would come down a lot easier.

I flew it one more time, sorry no video, but stuck on another battery just as an additional balance weight. What a difference! The plane just cruised around - I was stunned how smooth it was. I even tried a bit of inverted flying, but I was on low rates and couldn't keep the nose up. A quick roll got me out of trouble.

I had a battery monitor on the battery and after about ten minutes of very satisfying flying the bleeper went off. As I coasted in for the landing, I had another brown-out/signal failure which lost me the elevator at the last part of the approach. The landing was bumpy but OK, but I think I’ll try another receiver.

So I added more weight, prettied it up, and put in another receiver. What a difference!

Overall I’m very pleased with this plane.My final CG is about 20-22% of the wing chord. If you look at my other recent build which I'll post soon – the Velie Monocoupe, you’ll see I'm having similar problems with finding the CG. Initially I was looking at somewhere between 25-30% of the chord – but again it was tail heavy. I’m concluding that for the Armin wings I’m building I should start with a CG more around the 20% of chord and work from there.

I was thinking about this monoplane fuselage layout and reckon it could be easily adapted to a number of turtledeck variations; cockpit well to the rear, single cockpit, enclosed cockpit, etc.

 The only issue is the access for the servos. A servo hatch would be easy enough. I found that if I stripped the paper from one side of the foamboard it could be coaxed into forming quite a tight curve, with the paper on the outside. 

Some more images after repainting.

COMMENTS

sailorJohn on June 9, 2013
I always use a carbon arrow shaft as spar , it takes care of strength issues but would be difficult to achieve dihedral but am open to suggestions.
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alibopo on June 9, 2013
Hi, I'll need to do a wing build and take pictures - hard to explain the sequence, though it wasn't too hard to do. The wire gets sandwiched in the foam spine, and I kept the paper on the lower part of the wing intact, only removing a little on the top to allow the dihedral to form. I also stuck a pad on top of the wing to further strengthen the join. Probably massively over-engineered, but that's the way I do it...
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hbxfzw on June 8, 2013
very good!!!i like this.
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sailorJohn on June 9, 2013
Take note. Plugged my spect 7 into a 100ma brick OOPS! this has LIFE battery "overcharged" did balance charge and discharge to 9.3v then recharged but after 5 min it swelled so bad it couldn't fit into the transmitter
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gmyers2112 on June 9, 2013
tape a small piece of cushion foam over the camera mic. Or fold over a piece of facial tissue and tape it on. It'll cut down the wind sound. Even days that don't feel all that windy will move wind over a mic.
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alibopo on June 18, 2013
Hi, yes, thanks for the suggestion. Foam pad now in place :)
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sailorJohn on June 8, 2013
Now that's what I'm talkin' about , a foamy that looks like a old time model. Try the armin wing with the same fuselage set in like the Baby Blender .I 've build several low wing similar planes that need 60% d/r and a little bit nose heavy,7IN wings fly in any wind but none of mine looked that good!
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alibopo on June 9, 2013
Hi, this is a modified Armin wing, the dihedral comes from careful cutting, plus a 2.3mm wire strengthening spar with a mid-point bend in it (basically what was in my box of bits). The foam on the end is just a cap to cover the end of the Armin wing. I did consider slotting the wing like the Baby blender, but reckoned I needed to maintain the wing's integrity. I'm pretty sure the Baby Blender top wing 'lends' the bottom wing some of its strength, which I think makes the BB cutouts possible. Regards flying in wind; from my limited experience, this is a pretty stable airplane. I've flown it with a few different battery/weight combinations - of course, the heavier the 'payload' the better it punches through the wind. The motor is a Turnigy 1500KV rated about 8A - roughly 90W of power, which isn't a great deal really. The plane's weight is 570gm / 20.1ozs including a 1000mah battery.
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sailorJohn on June 8, 2013
Folks this type of plane is the answer for those of us who are concerned about the wind,12---25--- who cares, if you do crash make another tonight.

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boarding pass on June 8, 2013
I like it! great build. good to see someone having a go at new builds. i have done a couple myself now with my own problems to overcome and a fiew dirt naps too. keep up the good work. what type of camera are you using? i was thinking of using my HK wing camera on my hat to film my flights but i cannot zoom with it so i think the plane might look too small.
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alibopo on June 9, 2013
Hi, I've been using a spectacle camera which cost about £12.00 from China via EBAY. Cheap and cheerful, gets most of the action if I remember to head-track, but it does seem to 'push' the image away and makes things a little smaller. The start of the video uses a small Hitach HD camera, which produces a much better image (ignoring the wobbles). The spec-cam has no zoom, but it did allow me to record something hands-free.
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jordy123 on December 9, 2015
I think the lines on the tape look great on black. Happy accident, as Josh Bixler would say.......
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alibopo on December 11, 2015
Hi again - this is a 'vintage' plane now. It's still flying, but with a slightly larger motor and flight stabilisation. It's my 'try stupid stuff' and 'strong wind' plane. It just keeps going and going. Far too heavy really, with all the repairs, etc, but it still flies fine. Cheers. alibopo
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"Tribewt" maiden - Baby Blender monoplane hybrid.