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Old Jul 15, 2011, 11:39 AM
smithy
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Cornwall, UK
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Thanks for your words of encouragement guys. Weather has taken a turn for the worst down here and looks like its set in for the weekend, so im limited to what i can do indoors.
Just glassed the 2 fan hatches, thaught i would do them while sitting in place so as to keep there shape.

Max, ive gone for no undercarraige on this one, going to use a 'dolly launch' instead as i was getting a bit worried about the weight. As this is a prototype i have gone back to the CAD drawings and shaved off quite a bit of weight for the one that will be kitted. This will also have provision for retracts, electric or pneumatic. I may even make up a custom set, but that's in the future. Those sequencers look cool by the way, looks like you got a bargain there Rich.

Still not decided which 70mm unit to use yet, i think either minifan or maybe the lander unit.

Phil
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Old Jul 15, 2011, 11:56 AM
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I don't scratch build as much as .... more like extreme moding =) and Rich is the expert but I came across the comment about glassing. If the balsa is already structural, then glassing need only be very light as long as the balsa is sealed from soaking in the epoxy.
So if the frame design is lighter you may do the outer shell the same way or stay close to the same and go lighter on the finish. Not sure which is the better .... talking out loud really.

Maybe you cut some entire sections in foam...the nose, wings, etc... just a thought.
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Old Jul 15, 2011, 12:22 PM
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a way to keep the future ones lighter, would be to use the current one as a mold, for FG shells/skin sections, that could be attached to a lighter, balsa/ply/CF skeleton. take your pick of materials for the skeleton, it really doesn't matter, as the strength would be mostly in the bonded skin panels.

Max, I'm no expert, trust me. LOL. I can talk the talk and walk the walk, but most of the time, my talk is better than my walk. hahahahahahaha.
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Old Jul 15, 2011, 01:44 PM
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Quote:
Originally Posted by LuvEvolution7 View Post
a way to keep the future ones lighter, would be to use the current one as a mold, for FG shells/skin sections, that could be attached to a lighter, balsa/ply/CF skeleton. take your pick of materials for the skeleton, it really doesn't matter, as the strength would be mostly in the bonded skin panels.

Max, I'm no expert, trust me. LOL. I can talk the talk and walk the walk, but most of the time, my talk is better than my walk. hahahahahahaha.
Luv if thats the case then I use a walker and cane.

Would making it a single 100mm make its lighter. Its a full redesign and your comment about making a plug from the original etc.....
He'd have to hand it over to a production house though to kit it to us.... which .... ah ... I at some point would love one.
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Old Jul 16, 2011, 02:38 AM
smithy
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Cornwall, UK
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Im sticking with the balsa and ply method although I have seriously thaught about a composite model, there's a company just down the road that could make a mold out of this one like you said Rich. Ive altered cad drawings to make formers much lighter and also changed ply formers for balsa in the non stressed areas.
Max, I dont think a single fan would work very well as the exhausts are to far apart for a bifurcated exhaust to work, but then I could be wrong.
Phil
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Old Jul 16, 2011, 01:20 PM
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it's not the intake you've got to worry about. it's the exhaust. if the angles are too great, it won't work. to me, the angles look very sharp for a single fan. hard to tell when you haven't seen it in person though.
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Old Jul 16, 2011, 03:58 PM
DELTAS RULE
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2 70's will fly that thing just great.

a twin 90mm version would be pretty slick....and BIG
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Old Jul 16, 2011, 04:11 PM
smithy
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Cornwall, UK
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Twin 90 fibreglass!??
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Old Jul 17, 2011, 12:35 AM
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Max, I dont think a single fan would work very well as the exhausts are to far apart for a bifurcated exhaust to work, but then I could be wrong.
Phil
Quote:
Originally Posted by LuvEvolution7 View Post
it's not the intake you've got to worry about. it's the exhaust. if the angles are too great, it won't work. to me, the angles look very sharp for a single fan. hard to tell when you haven't seen it in person though.
That's too bad, I wanted to do a single in a smaller version.

If your wing span is 65" the width between the exhaust tubes should be about 4" or 4.5". Thats just a guess. If a 100mm is about 4" splitting and shifting the duct out 2"-2.25" from placing the EDF unit about dead center of the wing, 8" or so inches forward would be too tight a bend?

How much is too much for a bifurcated exhaust ?

Would it make a difference if you used some of the up and coming higher powered systems, EPFs Mercury or the Mach 2.75kg 70 and now the 5.6Kg 90.
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Old Jul 17, 2011, 02:41 AM
smithy
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Actually if it was smaller I dont see why a single couldn't work. Mine is 66'' span and the distance between exhaust centres is 7''.
Phil
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Old Jul 17, 2011, 07:33 AM
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I would say that if the fan was far enough forward and you had no inlet ducting, it might be ok. just use an inlet ring or a bellmouth of some sort. then again, I don't know what the distance is between intake face and exhaust. there may be room for full ducting. that would be your key number right there, along with the 7" spacing that Phil already said. the problem is trying to make a kind of "S" shape without overdoing the angles and also trying to make it as straight as possible coming out the tailpipe. actually, it wouldn't have to be straight coming to think of it. it would be ok to have the exhaust angle outwards. you'de lose some forward vector, but this isn't a speed demon by any means, so if you want to fly scale, who cares.
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Old Jul 21, 2011, 03:16 PM
smithy
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Started applying first coat of paint, excuse the plant in the forground. Wing was placed on top so as to line up camo markings.

Phil
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Old Jul 21, 2011, 04:23 PM
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oooooooooooooooh, I deffinitely like it a lot. your hard work is paying off. I'm glad you can see the light at the end of the tunnel. maiden is super close now.
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Old Jul 21, 2011, 04:37 PM
smithy
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Thanks Rich. What are you working on now?
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Old Jul 21, 2011, 04:39 PM
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working on trying to build a foam cutter that doesn't blow up on first try. hahahahaha.

we've got this groupd designed delta, if you've been following that. I"m waiting to get a hotwire cutter that works, so I can cut parts for it. other than that, I'm doing nothing. it's too damn hot to do anything. 50 degrees here today. I guess in your speak, that would be almost 130 degrees. just brutal.
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