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Old 04-16-2015, 07:05 PM
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Catrease01
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Hey guys let me say one of the posts here changed me to electric from in my head. The only problem is i dont really understand the motor/battery setup from a scratch build. Im very handy at wood working and plan to build from balsa. I got a few questions if you know the answer id appreciate ur response. Im looking at a 36" wingspan plane capable of loops aileron rolls so atleast 4channel. Lipo battery powered.

1. Are two props better than one? Or is there diminishing returns at a point.
2. Why are low wings better for stunts than high?
3. Does dihedral shape do anything besides assist rolls?
4. Whats the minimum brushless motor i should use? The fancy nearly robptic names of the the billions of motors confuse me vs. Gas powered ones like .4 .5 .6
Thanks for ur input
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Old 04-16-2015, 08:31 PM
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Originally Posted by Catrease01 View Post
Hey guys let me say one of the posts here changed me to electric from in my head. The only problem is i dont really understand the motor/battery setup from a scratch build. Im very handy at wood working and plan to build from balsa. I got a few questions if you know the answer id appreciate ur response. Im looking at a 36" wingspan plane capable of loops aileron rolls so atleast 4channel. Lipo battery powered.

1. Are two props better than one? Or is there diminishing returns at a point.
2. Why are low wings better for stunts than high?
3. Does dihedral shape do anything besides assist rolls?
4. Whats the minimum brushless motor i should use? The fancy nearly robptic names of the the billions of motors confuse me vs. Gas powered ones like .4 .5 .6
Thanks for ur input
Hi Catrease and welcome to Wattflyers

1. Are two props better than one? Or is there diminishing returns at a point.

Normaly one prop is all you need, it depends on the plane too, a motor with 2 props that turn in opposite direction is good to cancel out prop torque but normally its not needed.

2. Why are low wings better for stunts than high?

Normally a mid wing is better for stunt flying, because the wing lift force is at the middle of the fuselage and your not fighting lift force at the top or bottom of the plane.

3. Does dihedral shape do anything besides assist rolls?

IMHO dihedral helps to stabilize a plane in flight, great for a trainer, but it does nothing to assist in making rolls, a straight wing is better for rolls, because dihedral will fight a roll.

Dihedral and Wing Chord are two different things,



4. Whats the minimum brushless motor i should use? The fancy nearly robptic names of the the billions of motors confuse me vs. Gas powered ones like .4 .5 .6

What you want to do when starting out building is use motor prop thrust, its a lot easier than trying to use Watts, as Watts can be very confusing, a small motor can draw lots of watts and have very little thrust to where a larger motor can draw low watts and give lot of thrust, look and use the motor pages at Heads up Rc, Jeff supplys a lot of motor to prop to lipo to esc usage info for a lot of different size and weight of planes, I have learned a lot from the HURC motor pages when first starting out, HURC motors and parts are used by a lot of people here on Wattflyers, and everyone is happy with HURC products and fast turn around time.

Its best to use a motor prop combo that will give you a 1 to 1 power ratio, Example, if your planes all up weight, AUW is 30oz with everything installed, then you want to use a motor combo that will deliver 30oz of thrust. or more I build my planes to have a 2 to 1 power Ratio my planes leap up into the air, no need for a taxi roll More power LOL


http://www.headsuphobby.com/Power-Up...otor-E-690.htm
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Old 04-16-2015, 08:34 PM
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If you have any questions, please feel free to PM me, and I should be able to point you in the right Direction.

here are some of my Scratch built planes that I have done on Wattflyers.

http://www.wattflyer.com/forums/showthread.php?t=55444
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Old 04-16-2015, 10:39 PM
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Ok chellie so after reading your post and another sites post ive decided im just gonna go for it. I got some extruded polystyrene. The blue insukation stuff from lowes im gonna glue together and shape. Quick question. If i make this out of this foam should i hollow the foam out or just leave it solid? Ive sculpted with this stuff before and im going to shave it down to a round shape overall.
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Old 04-17-2015, 01:36 AM
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Originally Posted by Catrease01 View Post
Ok chellie so after reading your post and another sites post ive decided im just gonna go for it. I got some extruded polystyrene. The blue insukation stuff from lowes im gonna glue together and shape. Quick question. If i make this out of this foam should i hollow the foam out or just leave it solid? Ive sculpted with this stuff before and im going to shave it down to a round shape overall.
A Lot depends on how heavy the Foam is, you will need to hollow out the fuselage for control rods or wires going to servos, Also I would put a piece of Carbon fibre in the wing, so it stronger, one 10mm square CF hollow tube will work well. use 5 or 15 min epoxy for the build, use thin /sparingly as epoxy is heavy

give the main wing and stabilizer a 0 - 0 incidence, give the motor about 2 to 3 degrees of down thrust, mount the motor so you can add washers to shim the motor for down thrust and right or left thrust, just have down thrust for now, fly the plane and add side thrust if needed, Normally a 25% of the wing width from the leading edge back is the CG and is a safe place to start at with a front mounted wing, that does not apply to deltas or pusher jets.



you may want to hot wire the wing.

https://www.youtube.com/watch?v=yIxyyTnT-hM

https://www.youtube.com/watch?v=ckxnNRSM3YE

https://www.youtube.com/watch?v=KXWWnPIhk44



http://www.rcfoam.com/carbon-fiber-s...ube-p-844.html
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Old 04-17-2015, 05:46 AM
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Definatley gonna hot wire it.
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Old 04-17-2015, 10:15 PM
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Got all my stuff for hotwire setup ill post it later
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Old 04-18-2015, 04:41 AM
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Click image for larger version

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Old 04-18-2015, 05:15 AM
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Seen worse first time attempts at foam core cutting
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Old 04-18-2015, 05:23 AM
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Definitely second buying from hurc. Made two orders just this week. Lol
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Old 04-18-2015, 05:24 AM
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Its really easy if u have a old style battery charger.
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Old 04-18-2015, 08:07 AM
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Originally Posted by Catrease01 View Post
Good First try It takes a little practice, cut out you wing patterns out of Aluminium, and sand the pattern smooth so the wire does not hang up on the pattern. That will make for a very smooth hot wire cut
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Old 04-18-2015, 08:19 AM
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The patterns don't need to be aluminum... but shouldn't be a soft wood. 1/16 aircraft plywood works well. Smooth edges are very important.

the deep ridges are from the wire getting stuck and temp being a bit higher than it should be.
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Old 04-18-2015, 03:59 PM
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Ya i figured that was a proof of concept cut i used a jack saw to cut the template out haha
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Old 04-18-2015, 04:46 PM
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I had a small biz cutting wings and odd stuff years ago ....

a) Wire must be TAUGHT ... I mean REAL TAUGHT. We used a Spanish windlass affair - like the old woodsaws where you turned a length of wood between two ropes ... tightening the H bow. When wire warms up - needs extra turns.
b) Too hot and you get dips and craters when you alter speed of pull through due to wire melting foam around when slowed.
c) Not hot enough and you get rough cut due to foam cooling and sticking to wire making it drag.
d) Templates have to as smooth as babys bum ... ANY slight imperfection and your wire will catch.
e) Better to leave out spar slots and other cutouts till AFTER wing blank is cut as a basic shape. Only real experienced steady handed people can cut all in one pass ! I never could ! I cut basic blank then after did vertical wire drops to make the slots for spars.

I notice you used Blue Foam ... now that is as I find - the harder foam to cut as its more dense. I used to practice on standard white foam ... in those days EPS was the basic foam for veneered panels ... with blue as the more expensive and heavier ...

It really takes practice to get it right. Tapered wings - I was never good at, but a pal of mine rigged up a table for me that you dialled in the ratio of tip to root and then wound a handle to draw the wire through. Silly me - when I left UK - I gave it away !! Sure wish I had it now !!

Nigel
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Old 04-18-2015, 05:01 PM
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Catrease01
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That table sounds awesome. The way ive decided to make my wings is with a secondbpair of hands. One of us take the wire amd follow one template and the other follow another template for the other side of the wing. That was a 20ga galvanized steel wire with 10 amps running through it. No resistance at all from the foam. Easier than cutting butter
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Old 04-19-2015, 07:22 AM
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When I first started to hot wire wings, i struggled with patterns, I use Formica at first, hoping it would not burn and cause the wire to hang up, Formica did burn some notches in the pattern and foam, and that was harder and stronger than Plywood, So i used Aluminium Patterns, problem solved, no more burning notches in the pattern and it gave me a very smooth cut, some people may not need to use aluminium patterns, but it was the cats Meow for me





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Old 04-19-2015, 07:34 AM
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One second chellie ill show u what i endedbup with for my fuselage cutout
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Old 04-19-2015, 07:37 AM
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Default current fuselage.

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Old 04-19-2015, 07:43 AM
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Originally Posted by Catrease01 View Post

Cool Just stay with it, its a learning experience thats for sure I kept getting better and better at cutting foam the more i did it, at first my foam hot wire cuts looked like Sheet

I made this hot wire cutter for smaller pieces of foam, it works great

https://www.youtube.com/watch?v=kF-s4xmaDnQ

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Old 04-19-2015, 07:46 AM
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Hey chellie idk if you know. Km sure you do. I just posted a thread jn the esc servo rx tx thread could u look at it and see what u. Can tell me.
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Old 04-19-2015, 07:50 AM
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Originally Posted by Catrease01 View Post
Hey chellie idk if you know. Km sure you do. I just posted a thread jn the esc servo rx tx thread could u look at it and see what u. Can tell

me.
Sure
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Old 04-20-2015, 04:56 AM
  #23  
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Mines runnin fine. I got it running at 10 amps and ive also ran a load tester for car batteries within the circuit to act as my variable resistor. Goes right through. I got my wings cut out today next step is to shape the profile. The particular shape of these wings are such there is no 90degree angles so in a non industrial garage without the assitance of a laser is trying ha but ill get it.
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Old 04-20-2015, 04:58 AM
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What i do need is a recommendation of fuselage thickness. Before i profile i need to get my thickness right. This plane has a 48inch wingspan amd fuselage is 36 inch long? It is currently 5.25inches wide. Anyone got a similar size plane that can measure how wide ur fuselage is? The 5.25 was just so i could start working on it
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Old 04-20-2015, 06:02 AM
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Originally Posted by Catrease01 View Post
What i do need is a recommendation of fuselage thickness. Before i profile i need to get my thickness right. This plane has a 48inch wingspan amd fuselage is 36 inch long? It is currently 5.25inches wide. Anyone got a similar size plane that can measure how wide ur fuselage is? The 5.25 was just so i could start working on it
on a hitec extra 300, the front of the fuselage is 5.8" wide and it tappers towards the rear of the fuselage, here is a foam cowl from tower hobbies for the front of your plane

Cowl for the Extra 300S Airplane

Tower's Low Price
$8.99



SPECIFICATIONS Length: 1.9" (49mm)
Width: 5.8" (147mm)
Height: 4.4" (113mm)





http://www3.towerhobbies.com/cgi-bin...?&I=LXEENL&P=7













Build your plane similar to the hitec extra 300

http://hitecrcd.com/products/airplan...-300s-/product

Last edited by CHELLIE; 04-20-2015 at 06:24 AM.
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