Scratch build McDonnell XP-67
02-07-2018, 11:13 AM
#76
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You may find the thread below to be of interest, although you may wish it had been available when you started this project!
Warbird Information Exchange ? View topic - McDonnell XP-67 Moonbat, from the factory to the field ...
Warbird Information Exchange ? View topic - McDonnell XP-67 Moonbat, from the factory to the field ...
02-07-2018, 05:19 PM
#77
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Hey thanks chad. I actually have viewed all the info you linked when I was researching in the beginning. I found an alternate page with those drawings but they are the ones I used for the basis of the build. So I’m still waiting on epoxy. I decided to foam core the overweight fuse. I learned a couple things 
pour all the foam at once. I also built a hot box, so I can pour the foam in really hot ambient. I want max expansion. My foam is currently at 10oz. I think I can get it down to 8 if I get everything hotter. I savaged the foam on this one, when I make the flyer I am going to hot wire the foam cutouts. Exciting times!
Videos!!
pour all the foam at once. I also built a hot box, so I can pour the foam in really hot ambient. I want max expansion. My foam is currently at 10oz. I think I can get it down to 8 if I get everything hotter. I savaged the foam on this one, when I make the flyer I am going to hot wire the foam cutouts. Exciting times!Videos!!
Last edited by Mms_citrus; 02-07-2018 at 05:22 PM.
02-07-2018, 08:54 PM
#78
Throw some .60's on that beast, it's strong enough! Love the videos.
02-09-2018, 12:26 PM
#79
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Haven’t done any major work. Just been messing around with electronics and stuff. Going to do some more stuff tonight, lay up a new bottom. Epoxy came in yesterday and mixing supplies so I am going to mess around with it tonight
02-09-2018, 02:10 PM
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Those servos I got are dirt cheap from that place. 2.90 a servo. Lol. I paid 5 bucks a piece on amazon. It’s a convenience thing tho with Amazon. The hobby king stuff, like the esc motor and battery are kind of hard to beat on price. That battery is like 24 bucks, the motor was like 27(motor isn’t super cheap but from what I’ve read his is supposedly a pretty good motor, it’s definitely got the juice I was looking for) and the esc was 11...China man. And it’s not like China a decade ago...stuff isn’t really that bad. I’ve cycled it all a few times, ran it wide open till it shut off. It’s pretty decent. I don’t expect the same from this stuff as I would some high dollar equipment, but again I’m not paying a lot ya know. I’m gonna probably auger this first flying model anyway....
02-11-2018, 03:39 PM
#83
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I’m gonna look into them some more.
I bonded the halves today. Glued in the bulkheads. From looking in thru the foam holes I can see that it looks like the bulkheads has enough putty on them and are glued all the way around. Gonna let it sit up and Tuesday morning probably foam it.
I bonded the halves today. Glued in the bulkheads. From looking in thru the foam holes I can see that it looks like the bulkheads has enough putty on them and are glued all the way around. Gonna let it sit up and Tuesday morning probably foam it.
02-12-2018, 04:42 PM
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I bombed again on foam.........I panicked and didn’t mix it long enough. First pours I didn’t get barely any expansion. I planned on 3 pours within a minute of each other. Ended up doing a fourth. It mostly filled the cavity. One wind didn’t get foam in it. I realize the mistakes I made and I will start another fuse in a couple days. This one is at least straight enough to do a complete mock up. I filled the wing out of the mold, it over expanded so I cut the skin and sanded it down. Mixed up thickened epoxy brushes it up and taped it up. When it all kicks over I’ll clean it up and start finish work and gear mounting. This one because of the extra foam I had to add, because I suck, is overweight so I may not try to fly it. I’m not sure yet and I’m still a couple weeks away from that anyway. The picks show the air gaps where the foam settled back down a bit. It’s mostly rigid and solid. Technically it’s fine to fly it’s just fat. I have no structural concerns. It came out good otherwise. Very little surface repair and seaming to be done for paint.
02-14-2018, 04:17 PM
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So I went with it anyway. I’m 4 ounces over my target weight so far. I’m going to keep on plugging away. Gear mounts are done. I’ll see how the rear ones hold up. The remaining pics are all the cooling and equipment cut outs. Last pic crudely shows the airflow path.
02-21-2018, 07:26 PM
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I worked on he plane some more. The wing bonding came out perfect. I’m really frustrated with the foam. I keep telling myself “screw it just make it fly and make another” but I’m having trouble with that. I started the horizontal stab mold, then totally wrecked the plug, so I’m trying to decide if I start all over or salvage the plug.....it’s a mess......I ordered vacuum bagging supplies and a couple foam core pieces to experiment with a true composite layup. I am just kinda frustrated right now. I’ll decide what to do with the stab tomorrow morning. I’ve been staying up late and getting up late so my time to work on the plane has been more limited. I usually get up at like 5am and work on it for 4 or 5 hours. Haven’t been. I need to get motivated again....I also need to find a new transmitter for cheap if anyon knows anyone with something decent. Blah
02-22-2018, 06:00 AM
#93
I worked on he plane some more. The wing bonding came out perfect. I’m really frustrated with the foam. I keep telling myself “screw it just make it fly and make another” but I’m having trouble with that. I started the horizontal stab mold, then totally wrecked the plug, so I’m trying to decide if I start all over or salvage the plug.....it’s a mess......I ordered vacuum bagging supplies and a couple foam core pieces to experiment with a true composite layup. I am just kinda frustrated right now. I’ll decide what to do with the stab tomorrow morning. I’ve been staying up late and getting up late so my time to work on the plane has been more limited. I usually get up at like 5am and work on it for 4 or 5 hours. Haven’t been. I need to get motivated again....I also need to find a new transmitter for cheap if anyon knows anyone with something decent. Blah
02-28-2018, 04:24 PM
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ive been tinkering with it a bit. got all my vacuum bagging supplies in and im messing around with foam types for a true composite layup. will update when some more progress is made.
03-03-2018, 04:17 PM
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The pourable foam is my problem. I can’t get a good way to pour it all in one pour and still fill out the wings etc. I don’t have enough foam to try again. I don’t really wanna try it again. I think I can get more consistent results other ways. It’s possible it’s the brand but I don’t know how different various expanding foams can be. I also have been using the slowest hardener I can get which supposedly yields one of the stronger laminates but also the most flexible. I’m moving to a medium hardener. I got a longer piece of wire for my hot wire foam cutter and I’m going to experiment with some blue foam from Lowe’s for coring. Cut it down to 1/8” or something. I think it would be exceptionally light. The foam core sheeting I purchased from a composite supplier is very strong. Good compression and torsional stability. It is heat shapeable. Made specifically for composite laminations. Last couple days I’ve been making mold repairs and polishing stuff. Working on the horizontal stabilizer mold too. Coming along good. I’ll probably start another layup next week. I’m waiting on the new hardener
03-03-2018, 04:23 PM
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ive kinda answered it but also it’s really temp sensitive and the mixing is tricky. You have to mix it practically until it starts expanding. The plane is relatively small so it’s hard to pour it all in fast enough. Just not the right choice for this specific plan. I’m sure someone could do it, but I don’t have enough experience with it.
03-05-2018, 09:22 AM
#100
Flyer, while it might do the trick, you do know that massage wand is a euphemism for a particular sort of percussive device don't you?