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The Beginners Guide To Flying RC Airplanes Second Edition

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#1) 
PostPosted: 31 May 2012 17:59 
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Joined: 30 May 2012 17:04
Posts: 21
Location: North Fort Myers, Fl.
I hope it's ok to copy a post I've already used on another board (If I were good at boards I would have been a carpenter)

Confusing CG info - I gotta get this right.
Got a new plane and the center of gravity graph is hard for me to understand, can you help me with this?

Things I've already changed:
Added a 6oz. sound unit in the belly.
Went from a 1800 MAh to a 2200 MAh battery.

Things I might do:
Change to a lower pitch prop to bring up power and RPMs
Add a gyro to the rudder

So if you would look at the photos and help me understand it may save me from crashing it first time out.

"Fly it nose heavy it flys bad. Fly it tail heavy it flys once"
- Peter Carpenters book



Sure would like to use the 'Factory setup that came with it (see picture above) but I don't understand it can you look at it and give me an Idea?

With battery (1800 MAh that came with it) its weighted 42.5 oz or 2.65 Lbs. With 2200 mah, sound unit and wires it now weights 50 oz or 3.175 Lbs.

DJ


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CG-2-2.jpg
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CG-1-2.jpg
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Last edited by Sculptor on 31 May 2012 18:15, edited 1 time in total.
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#2) 
PostPosted: 31 May 2012 18:11 
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Joined: 05 Mar 2012 16:50
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Location: Arkansas, USA
Any info you could provide about the model itself would help!

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#3) 
PostPosted: 31 May 2012 18:25 
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Location: North Fort Myers, Fl.
jmax26 wrote:
Any info you could provide about the model itself would help!


Josh,
Here is the plane.

http://www.bananahobby.com/2309.html

This is a lot of stuff to look at but if you scrole to the bottom the specs I think you want are there.

Thank you for taking an interest.
DJ


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#4) 
PostPosted: 31 May 2012 20:16 
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Sculptor
Did you fly it with the factory set up?
If it was ok then you could return it to its original set up and find out where the CofG was.
As long as it balances at the same point with the extra bits in you should be ok.

You are adding quite a bit of weight so you might well need a bit more power - it rather depends of how much power reserve the plane has in the factory set up. Yes, a finer pitch will increase the revs but with an electric motor that will actually reduce the motor power.
Increasing the props pitch and/or diameter would increase the power but whether this is a viable option will depend on how close to their limit the motor and ESC already are in the stock set up. It is quite easy to destroy either by over loading.

I hope this helps.


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#5) 
PostPosted: 31 May 2012 23:06 
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Joined: 13 Oct 2010 19:47
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Location: Lawrence, Kansas, USA
Quick Google search later... ;)

http://www.rcgroups.com/forums/showthread.php?t=297565
http://www.modelairplanenews.com/blog/2011/04/12/balancing-biplanes/

The second link seems to have more specific info, but get ready to do a little math. Since the wingtip chord isn't actually all that different from the root chord, the calculations will be a little easier.
...And taking a second look at that picture with the CG mark on it, it looks like the lines are the max forward & rear CG positions you can use. As long as the CG is within that range (between those two lines), it looks like you should be fine. For a maiden flight, it's always best to have the CG as far forward as you can get away with.

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Gravity is a myth; the Earth sucks. ;)


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#6) 
PostPosted: 01 Jun 2012 09:02 
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Welcome to the forum DJ.

Is there no reference to the CG in the manual at all??

By adding the weight that you are, you will increase the wing loading and this will increase the stall speed. I don't know how much success you'll have trying to fly at a scale speed, as per your other post. I guess you'll be ok for cruising around, but be very careful when landing. When you do get airborne, test the stall at a safe height!

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Pete


My site is rc-airplane-world.com, a beginners' guide to radio control flying.


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#7) 
PostPosted: 01 Jun 2012 17:18 
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Location: North Fort Myers, Fl.
quorneng wrote:
Sculptor
Did you fly it with the factory set up?
If it was ok then you could return it to its original set up and find out where the CofG was.
As long as it balances at the same point with the extra bits in you should be ok.

You are adding quite a bit of weight so you might well need a bit more power - it rather depends of how much power reserve the plane has in the factory set up. Yes, a finer pitch will increase the revs but with an electric motor that will actually reduce the motor power.
Increasing the props pitch and/or diameter would increase the power but whether this is a viable option will depend on how close to their limit the motor and ESC already are in the stock set up. It is quite easy to destroy either by over loading.

I hope this helps.



No Sir, I've not flown it, I'm still learning to fly (trainer = Sky Sufer power glider). The Staggerwing with original 1800 MAh bat wt. is 42.5 oz, with the sound system and 2200 MAh bat. is 50 oz. Total additional Wt. = 7.5 oz.
Have I gone too heavy do you think?
I understand about the prop being on an eletcric motor

Wingspan: 1030mm (40.5 inch)
Length: 850mm (33.5 inch)
Flying Weight: 1060g (37.4 oz)
Drive System: 3536 850KV brushless outrunner motor
Speed Controller: 35amp brushless ESC w/ 4A SBEC
Servo: 4X 9g high speed micro servos
Retract System: Servoless Retracts
Battery: 11.1V 3S 1800mAh 25C Li-Po
Control System: 2.4GHz Multifunctional Transmitter and Receiver
Radio Control Range: 3000 feet (1000m)

Thank you for this,
DJ


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#8) 
PostPosted: 01 Jun 2012 17:25 
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Joined: 30 May 2012 17:04
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Location: North Fort Myers, Fl.
Pete wrote:
Welcome to the forum DJ.

Is there no reference to the CG in the manual at all??

By adding the weight that you are, you will increase the wing loading and this will increase the stall speed. I don't know how much success you'll have trying to fly at a scale speed, as per your other post. I guess you'll be ok for cruising around, but be very careful when landing. When you do get airborne, test the stall at a safe height!


Yes Mr Carpenter,
Here it is. I've added 7.5 oz extra weight

Thank you,
DJ


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SW CG.jpg
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#9) 
PostPosted: 01 Jun 2012 17:34 
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Joined: 30 May 2012 17:04
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Location: North Fort Myers, Fl.
kalain76 wrote:
Quick Google search later... ;)

http://www.rcgroups.com/forums/showthread.php?t=297565
http://www.modelairplanenews.com/blog/2011/04/12/balancing-biplanes/

The second link seems to have more specific info, but get ready to do a little math. Since the wingtip chord isn't actually all that different from the root chord, the calculations will be a little easier.
...And taking a second look at that picture with the CG mark on it, it looks like the lines are the max forward & rear CG positions you can use. As long as the CG is within that range (between those two lines), it looks like you should be fine. For a maiden flight, it's always best to have the CG as far forward as you can get away with.


WOW! Thank you Scott. I think I can use the two sites to do this,

DJ


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#10) 
PostPosted: 01 Jun 2012 18:30 
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Joined: 13 Oct 2010 19:47
Posts: 159
Location: Lawrence, Kansas, USA
I see you have 4 servos listed, but the description on the BH site lists 6 servos. If you do install the flap servos, having them will allow you to do slower takeoffs and landings, but the higher wing loading will have an effect. As Pete said, test out the stall characteristics (both with and without flaps) while you're pretty high up in the air. Don't want to be surprised by it when you're 4 feet off the ground... :o

All this is, of course, after you have LOTS of experience with that Sky Surfer. Do you have it set up as the 3-channel or 4-channel? I'm not sure I'd consider a Staggerwing to be a good second plane (especially with the extra weight), and definitely not a first 4-channel... If you don't have a 4-channel plane, you might want to look at either getting a pair of servos for the Sky Surfer, or getting another trainer/intermediate plane.

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Gravity is a myth; the Earth sucks. ;)


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