indoor plane motor thrust questiom - RC Groups
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Jan 06, 2012, 11:21 AM
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indoor plane motor thrust questiom

I have built this little 22 gram 14" span foamie usting the radio brick/ battery from my crashed Porto Max heli. All I have left to do is mount the battery and glue the motor in. The motor is not fixed in yet and can move a little up and down. My question is, should I put in a little down thrust or a bit of up thrust? Or should I glue it in level? RCNutt
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Jan 07, 2012, 02:47 AM
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starscream4002's Avatar
I'm guessing two or three degrees of down thrust should be OK. But again your wing angle of attack is about zero.

Jan 07, 2012, 07:07 AM
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Thanks for responding starscream4002. It may not matter anyway because after I got it all together the rx has failed several times to activate. The blue light comes on but nothing happens. I does activate occasionally after I try it several times. I'm not sure what is going. It may be a bad connection not allowing the full amount of juice to flow to the brick. I'm going to try and clean the connectors in the battery box, but I don't feel very hopeful right now. The wing does have a couple of degrees of up angle. I have glided it across my basement and it glides well. I think I well silicon the motor in at about zero degrees. RCNutt
Jan 07, 2012, 07:36 AM
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starscream4002's Avatar
OK then. You'd better take off the black plastic on the battery carefully and get some smaller connectors on there.(for weight saving and making it failure proof.) That's what I did to my nine eagles batt and I can post pics here if you want.

Jan 07, 2012, 07:50 AM
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I'm concerned that the two carbon fiber fuselage booms are not stiff enough. They will probably bend when you operate rudder and elevator controls, which could lead to odd behavior.

Jim R...
...behaving a little oddly himself, lately...
Jan 07, 2012, 07:54 AM
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sporadic failure and downthrust

about your radio 'failure', my experience is that 1 of my rx occasionally just does not go on. the 1st time i panicked, but after a long time using it i have become accustomed to just turn it off and on until it is in the mood to go, and after that, everything goes fine. or maybe a false contact, and as suggested, trying cleaning contacts could help.
about the downthrust, again, my experience is that you have to make the mount adjustable and adjust the angle as required. hard to predict.
perhaps using something like uhu por, that can be softened with ronsonol, you can change it as many times as you need until find the right angle.

hope this helps
Jan 07, 2012, 01:34 PM
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Thanx guys, for writing in. I cleaned the contacts with some 90% alcohol and that seems to have worked. Yea! The motor ended up almost level. The carbon rods seem to be stiff enough. I don't believe small amount of flexing would hurt the flight performance too much. I'm not as sure about the thin 1mm (I think) pushrods. On some of my models I have made a little pushrod supports out of thin plywood about halfway down. I may do that with this model too. There is some wind here today but I flew it the length of the garage and out the door. Not much time to evaluate the flight characteristics because as soon as it was outside it was blown sideways into my truck. No harm done. The other concern I have is the balance. It balances at about the halfway point of the wing. I have to add weight to the nose or add wire to the battery box connector and move it forward. It did seem to fly kind of fast. I was thinking I might add tape on a couple of inches of foam as wingtips to increase the wing area in order to slow it down. I can always take them off it is too heavy. AWhat do you all think? RCnutt
Jan 07, 2012, 06:58 PM
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Wing stretched on mindoor plane

I decided to add on some wing tips to be able to fly it slower. I taped on about 3 inches to each end. The plane just went up 2 grams to 24 grams AUW. The only big concern is where the balance point is at about 50% of the chord. I'll have to see if it will fly there. I glided it in my basement and it glides very well now. My next chance to fly it unfortunately, will be next friday. Our club has a time slot from 1-3 at a senoir center that has a small gym.
Jan 07, 2012, 08:42 PM
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welcome to the world of designing model airplanes!
from all that i have learned with this kind of models, be symmetrical or undercambered airfoil, is that the only way to make them fly is with the cg at 1/3 of the chord. let's see what you get when you have the chance to perform real flights at the gym. the horizontal tail works fine with 20 to 25% of wing area.
if you have the time you can give a look at my blog and see my planes. somewhere i even show plans of 1 of them (the elf 18").
Jan 08, 2012, 02:26 PM
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Hi Phil. I did get a chance to fly it outdoors this morning. It was cold at around 30 degrees but the wind was almost zero. It flew pretty well and I got some long flights. The controls were quite sensitive. It did some "dipping". Minor stick movements worked best. I did find a broken spot in the elevator pushrod and there was "give" there. It was just barely hanging together. I was pretty pleased with it and I think flying in the gym won't be much of a problem. I am going to add a small piece of clay to the nose and see if that will make it easier to fly. Also I made a couple of 1/64" pushrod supports so the push rods don't flex as much. I did repair the pushrod too. I'll take a look at your blog if I can find it. RCNutt
Jan 08, 2012, 02:30 PM
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Phil, Where did you get your motor and bricks? RCnutt
Jan 08, 2012, 03:21 PM
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6400 bricks and motors (8mm single cell, and park 180 2 cells), from horizon; other motors like 1811-2000 2 cells from hobby king.
there are other sources of 8mm's, like rcbabbel. he sells also cells with connectors that match.
you can reach my blog by clicking into my name at this post.
Jan 09, 2012, 05:47 AM
Registered User offers Hobby Zone ultra-micro Champ with 3-channel brick and motor with gearbox for $37.99. It's DSM2, so it's compatible with DX6i, DX7, and DX8 transmitters. I have a set of that gear in a small Super Dart that weighs 27 grams without battery. It really scoots.

Jim R.
Jan 09, 2012, 06:33 AM
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That sounds like a good deal, unfortunately I don't have any 2.4 Tx's. Mine are on the old 72 frequency. RCNutt

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