The Biplane Forum > General Discussion > Hangar Talk > What could go wrong? Part 103 electric biplane made with Home Depot foam and plywood



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Old 10-17-2017, 07:26 PM   #26
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Part 5: https://youtu.be/xEqCt7GZo7M

Wings finished, G-testing. He will be installing a BRS.

About 8:10 in he starts talking about what it weighs. Without giving it away, I was surprised/impressed.

I was initially skeptical. I'm actually kinda excited to see it fly now.


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Old 10-18-2017, 12:01 AM   #27
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I'm still skeptical. His static load test wasn't really of any value. I posted a comment hoping to get him thinking about what really needs to be done as did at least one other viewer. He does listen so hopefully he'll re-do his test before he commits to a first flight.


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Old 10-18-2017, 12:43 AM   #28
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Very entertaining
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Old 10-18-2017, 12:43 AM   #29
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I'm no engineer, nor do I have any building experience really. What was lacking in his load test, out of curiosity?
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Old 10-18-2017, 01:17 AM   #30
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Everything the wings support must be part of the test, not just the pilot. If you look here you will see the static load test setup for the Polecat biplane a bunch of us designed in 1984. That airplane is similar in weight and mission to the one in the videos. The weight on the wings is 2160# representing 5 negative G's (the negative loads were worse case for us). If I remember our initial design gross weight was 475#, the 5G number shows we're loading 5 x 432# which I believe is the weight of everything except the wing structure. And notice that the airplane is not level, it is being loaded at an angle that mimics the lift vector of the wing which is about 10 degrees forward of perpendicular to the wing.

Another thing not apparent in the photo is that we recorded where the wingtips were before loading the wings and made sure they returned to that same position when the weight was removed.

So, he needs about 900# on his wings to test to a 2G load, not 600#. Having the airplane supported by the center section of the upper wing is not correct either (I think ours had supports at the firewall and tail) and he has not accounted for the lift vector nor has he done anything to demonstrate the structure did not yield during the test. We also did separate load test of the horizontal and vertical tail feathers.
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Old 10-18-2017, 02:35 AM   #31
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I think it'll fly. .crude, but I do think with enough power, it'll get up. What does everybody think about not having diagnal supports in the wing to prevent the wing from shearing back due to air loads?
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Old 10-18-2017, 02:49 AM   #32
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The foam and the fiberglass covers the drag/antidrag just like any other composite plane. In a way it reminds me of a Wing Ding. The WD never had power to fly high. If you had a 1000 acre farm field, you could cut figure eights and pick flowers with the wing tips. Most of us see a bunch of work for very little flying; this kid will probably build 20 homebuilts. His karma can afford a throwaway experiment.
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Old 10-18-2017, 11:56 AM   #33
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The strap fittings for the flying and landing wires should cross the spars in line/parallel with the wires themselves. With the fittings not in line with the wires there is a moment and sheer load on the bolts. 'Pulling' the wires tends to want to change the direction of the fittings on the spars.
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Old 10-18-2017, 12:03 PM   #34
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I saw that too Ed. If he puts 900# on the wings he may see why that's important.
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Old 10-26-2017, 06:49 AM   #35
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Part 6! https://youtu.be/O6sy5bt4D-Y

Ailerons built, covered in what appears to be model aircraft covering? 2, upper wing.

Wings finished and glassed.

Motors, mounts, throttles. I wonder what thrust analysis, if any, was done around the motor mounts.

Maybe it's just because it's not assembled fully in the basement, but I don't see any bracing on the *underside* of the horizontal stabilizer. I wonder if that would help with what looks like a bit of flutter when he powers up.
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Old 10-26-2017, 07:11 AM   #36
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jpr
I have to agree I didn't see your comment about the tail until after I watched the video and I have to agree that was the first thing I saw. if he doesn't brace the tail from the bottom the 1st flight wont take to long. as I see that separating from the fuse.
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Old 10-26-2017, 10:03 PM   #37
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I think all it has to do is make a couple of 100-200ft hops to be considered a success. He does not have the power to go high anyway. I hope he does not try without lots of hops. At best he probably does not have more than 3 minutes at full power.
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Old 10-26-2017, 11:39 PM   #38
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Default What could go wrong? Part 103 electric biplane made with Home Depot foam and plywood

I hear he made some hops, probably in ground effect.....no idea why he would do it when it's dark, but I hear the nose needs some repair now. I didn't really get a chance to watch it yet (my son told me about it) but it's apparently posted on his channel
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Old 10-27-2017, 12:19 AM   #39
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Yep, looks like he hopped it... starting at "about 45 minutes after sunset". Haven't watched the whole thing, since it's a livestream and I didn't have the patience for the whole (unedited) thing.

https://youtu.be/XMrbdLfG8dg
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Old 10-27-2017, 12:28 AM   #40
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Ya know, I was all for this guy even with all the poo pooers....Very inovative construction and determined to do something with the skills he knows. I was really rooting for him until I saw the first “flight” wtf..... at night??????
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Old 10-27-2017, 12:36 AM   #41
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That type of impatience does not bode well for the flight test program. He needs to take a deep breath and not play to the camera.
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Old 10-27-2017, 02:04 AM   #42
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Ditto Chris & Bill. Judgment appears lacking, this will likely not end well.
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Old 10-27-2017, 02:48 AM   #43
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I was impressed with this guy, till tonight. Silly, silly boy.

If that thing is Part 103, it isn't allowed two powerplants, right?
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Old 10-27-2017, 03:04 AM   #44
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He is young and excited. Wanted to fly it so bad, not a great decision. In-experience got the best of him, he knew he didn't have enough power to really get up out of ground affect. Surprised none of the other folks stopped him and said let's do this tomorrow. It probably was a little better light than the video showed. I like him, I guess I am cutting him a little slack.
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Old 10-27-2017, 05:22 AM   #45
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Quote:
Originally Posted by Beej View Post
I was impressed with this guy, till tonight. Silly, silly boy.

If that thing is Part 103, it isn't allowed two powerplants, right?
Part 103 in its entirety is here. I didn't see a provision against electric propulsion or multiple motors (makes sense, since the Lazair is a twin-engine ultralight).

Interestingly, the LSA reg as currently written would prevent this from being an LSA two ways: 1 - it's got 2 motors, and 2 - the motors are not reciprocating engines. I think the EAA is working on getting that changed.
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Old 10-27-2017, 11:06 AM   #46
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I applaud his work but my ADHD won't let me sit through 15 minute videos.
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Old 10-27-2017, 01:09 PM   #47
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ADHD or is it you flat don't want too
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Old 10-27-2017, 07:54 PM   #48
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Guilty on both points, ADHD and I don't want to!!!
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Old 10-28-2017, 03:44 PM   #49
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wait a dang minute, a "20 something" exhibits impatience and dubious judgment... why I've never heard of such a thing....
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Old 10-28-2017, 03:49 PM   #50
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Good judgment comes from experience, and experience comes from bad judgment... Rita Mae Brown, Btw, I think I'll make a HUGE profit if I sell this Sport Biplane I just finished!


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