C-47 Building tips. - RC Groups
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Aug 09, 2004, 11:32 PM
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Hovertime's Avatar
Discussion

C-47 Building tips.


Well lets start a new thread dedicated to building, batteries, esc's, and setup questions, dedicated to C-47.

First question-what do you guys use to glue the fuse halves together?
GWS glue or epoxy, if so - what kind.

Also I'm still hoping that somebody who has C-47 with 3 servos will fly just using Ailerons/Elevator and Ruder/Elevator, so we can decide if its possible and safe to use 2 servos for it.
Lets have some fun!
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Aug 10, 2004, 01:58 AM
Registered User
My speedy is a 20amp, battery is a 2s 1200 etec.
For the first time i stuck the fuse together using gws glue, spread it on both sides let it dry for about ten minutes and stick them together, no rubber bands , no sticky tape it worked great. Make sure you line it up well, once you push it together no second go.
My first flight was mainly aileron and elevator but it does fly better with rudder input. once my decals are on i'll post a photo.
Happy flying
Big Al
Aug 10, 2004, 03:15 AM
MINE!
Mick Molloy's Avatar
My tips for building the C47.

Choose the cells you are going to use before glueing the fuse together, test fit them and if required remove some foam from inside the battery area before glueing the halves. (Learnt the hardway)

Where the Elevator and Rudder servos go drill a access hole for the servo leads end again beofre joining the Fuse halves. I also epoxied some thin ply to screw the servos into.

Use Durbo quick links instead of the z "BANDS" these are cheap and weigh nothing, they make it very ezy to set the controls in neutral position.

I will post some pics tonight to explain.
Aug 10, 2004, 05:52 AM
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Mick Molloy's Avatar
Here is the pic of the servo setup, I can't claim this idea as my own, I saw it on one of the other C47 threads.
Last edited by Mick Molloy; Aug 10, 2004 at 06:01 AM. Reason: Actually attaching the picture
Aug 10, 2004, 06:21 AM
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Mick Molloy's Avatar
Here is a pic of my battery area, I will be using 8 x 950 kan cells. The cells fit nice at snug in the std slot but they are a bit tall.
I need to remove some foam from the floor of the batt bay, this would have been much easier to do before joining the Fuse halves.
Aug 10, 2004, 01:05 PM
Always right
Hovertime's Avatar
I have Pixie 20P for esc, and motors have some RPM fluctuation, Anybody else has noticed this?
My friends Slow Stick had same problem, was cured by installing diode across motor terminals, I think I'll do it for C-47 motors too.
Great tips guys!!!
Aug 10, 2004, 10:55 PM
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Hovertime's Avatar
Took out my watt meter and did some testing - may be interesting for you guys-GWS motor charts seem to be not very precise-
With 2 motors in parallel amp draw:
5.5V 12A
6.0V 14A
7.2V 17A
8.4V 19A

I'm scared to think about amp draw with 3S lipos
This is at around 900feet above sea level and 24C temperature (76F)
So-maybe GWS testing facility is higher above sea level or what?
Aug 11, 2004, 02:06 AM
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Hovertime's Avatar
Mick Molloy-do you have wattmeter? What voltage those batteries are giving at C-47 motor loads? 8 of those cells can be of similar performance like 6 cell GP1100, or even worse. What amp draw do you guys measure?
GP1100 if going for 6 cell packs-
II
II
II Configuration would fit, but this :


III
III would allow pack shifting to get CG on the right spot.
What is the C-47 like ? Is it nose or tail heavy?
Aug 11, 2004, 02:32 AM
Registered User
it is very tail heavy if you go by the manual cg. I set mine at 75mm with about 1oz of lead pushed in the front of battery box, with 2s 1200 etec.
Aug 11, 2004, 02:50 AM
Always right
Hovertime's Avatar
Conder53-how long does it fly with those lipos? Whats your LVC?
Can you fly C-47 using just ruder/elevator?
Aug 11, 2004, 03:24 AM
Registered User
I had 2 five minute flights with rog, going to try for 3 flys this Saturday. I'll try using rudder and elavator only. Excuse my ignorance but what does LVC mean.
Aug 11, 2004, 05:20 AM
Registered User
Derek_TX's Avatar
LVC = Low Voltage Cutoff, to protect lipos which are hurt below 3v and die below 2.5v per cell.
Aug 11, 2004, 06:14 AM
MINE!
Mick Molloy's Avatar
OK guys I did my maiden on the C47 today, let me tell you the first flight was a bit scary, on 8 kan 950s this thing is a missle (by speed 400 standards). My C of G was set at the stated 55mm, this is as far aft as i could get it using the 8 cell pack without adding tail weight, this is way to far forward i will be moving to 70mm as per some other peoples experience.

The question of Rudder only, no chance I had a try and it would turn but no real authority.

I dont have a watt meter, I was using a 30amp speedy so i knew it would be less than that, I felt the pack after my second flight and was warm to touch but not hot. My second flight was around 4 min which means about 15 amps???

Only bad habit my plane had was when trying to loop it wanted to roll left quite bad, I dont know why this was the case, rolls are very nice with this plane. it looks fantastic doing a slow scale roll.
Aug 11, 2004, 08:21 AM
Go FASST or go home...
Ben_E's Avatar
Quote:
Originally Posted by Mick Molloy
.... rolls are very nice with this plane. it looks fantastic doing a slow scale roll.
Slow scale roll????

That's one c-47 manouver I haven't heard of before! lol what did the paratroopes say??

Keep the info coming I'm in the building process of mine, can't wait...

Ben_E
Aug 11, 2004, 08:25 AM
know it all
Hovertime how did you measure this?, you measured current at the battey pack?, how did you get the different voltages? variable power supply?

Ecalc says a 300h motor at 8.4v (measured at the motor) will draw 8.4A with the 5*3 prop.. times two this is 16.8Amps .. I would say close enough to the 19Amps that you are getting. When I try to simulate the lower voltages the amps are wildly off from what you measured.

I think I will limit voltage to the motor with the esc, to no more than 7-8Amps at the motor.. battery pack will only see 12 amps due to the esc. All I have is 3s lipos and dont feel like getting a 2s pack just for this plane.. I hope the Pixie 20 can take the partial throttle load.

Test a couple of new motors if you have them.. overheated motors will show a current increase from stock.

Herm

Quote:
Originally Posted by Hovertime
Took out my watt meter and did some testing - may be interesting for you guys-GWS motor charts seem to be not very precise-
With 2 motors in parallel amp draw:
5.5V 12A
6.0V 14A
7.2V 17A
8.4V 19A


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