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Old Dec 11, 2014, 07:26 AM
Registered User
Australia, QLD, Biloela
Joined Aug 2012
84 Posts
Build Log
Colonial Viper vii 64mm EDF

I've reluctantly started this b/l to maybe get some help/advise and help others to make this frame a viable flyer.......and it's Soooo cool!!!
Reluctantly because I'm not using plans (there are none) and Yes... I don't know what the hell I'm doing lol...I'm mostly putting it together "by eye".
So what I've got so far. ...64mm EDF, 60amp ESC, 2200mAh battery
I'm attempting this because no one else has been able to get it to fly with an edf.
All comments welcome...
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Old Dec 11, 2014, 09:00 AM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
3,163 Posts
Hey Dukejet!

Cool project! I have a little experience with making a Viper that works so if you have any questions let me know.

http://www.rcgroups.com/forums/showthread.php?t=907472

From what I have seen, there is no reason an EDF wouldn't work. The only issue will be Wing Area to Weight Ratios. What is the weight of your EDF, Battery and ESC?

My first attempt at the viper failed because i built it too small and it was a brick. When I scaled it up to 40" Long it worked great. Total weight for the 40" Long one was around 14 ounces.

How big is this one going to be?

I am following your progress. Let me know if I can help. I love seeing people work on cool designs like this.
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Old Dec 11, 2014, 10:56 AM
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Australia, QLD, Biloela
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Thankyou SG! I've read all your work and am a big fan. Your the reason I've found this project to do in the first place. So I'm stoked you are here to help.
I will have to post dimensions and weight when I get back to the work bench.
Yes I have one question, What controls did you have set-up on the profile you did? Like mixed elerons or Ailerons and rudder?
My first preference would be elerons the same as a delta wing, because the fear with this frame is it's ability to roll over so well...
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Old Dec 11, 2014, 06:05 PM
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Australia, QLD, Biloela
Joined Aug 2012
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Dimensions

So far my bird is 770mm long with the wingspan @ 675mm
Fan+ Battery+ESC+Frame with servo's and receiver = 545g!
Was quite surprised with the all-up weight being this low given I've only got some paneling to do on the front and rear. Thrust tube and start the pretty bits. May add another 50g to her??
What'd You's think?
The length will be a little bit shorter, I'll cut the nose to the right angle ( about where the tape is in the front-on photo). We'll see what happens. ...
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Old Dec 12, 2014, 09:10 AM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
3,163 Posts
I think your size is decent but the weight seems high to me. That is 21 ounces!! You might want to consider going with a smaller battery. A 2200 is a big chunk of weight. I have a bunch of 1200 mah batteries with a high C rating to handle the amps of an EDF. Your wingspan is a little bigger than mine though so you might be ok.

That is always the problem with EDF's they are heavy for the performance they put out.

For reference, my Viper balances right at the back of the cockpit on yours it would probably be right around the front of your foam inlet.

As to the roll issue, I didn't have a problem. I set mine up as a delta with rudder but almost never use the rudder. It flies more like a 3D plane when it comes to roll. It stays where you put it with no self correcting. So it isn't bad in my opinion.

Get this thing done and get it in the air!
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Old Dec 12, 2014, 10:01 AM
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Australia, QLD, Biloela
Joined Aug 2012
84 Posts
Thanks mate! Yeah the 2200 weighed 193gs...the bare frame only weighs 200gs! So I'll use a battery that gives me the correct balance. The fan is taken from my Sonic64, it runs on a 2200 but it's a huge wing.
I've fitted a 60amp ESC under the belly plate with air channels to carry the heat away.
I'm having trouble trying to figure out how to design the back section so I can remove it and get to the fan a when I need to. I'm tying to use the 2 holes just behind the fan mount so ican unscrew the back section that will contain the 3 exhausts. .....maybe?
I've ordered a Don's wicked 64mm edf all balanced and ready to go. So I'm getting as much done as I can between night shifts till the good gear turns up.
I'm thinking this thing has a tonne of power in a small frame, it should "go off it's tits" when she's finished...?
You must be patient Daniel son! Lol.... I can't wait either!
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Old Dec 14, 2014, 09:56 PM
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Australia, QLD, Biloela
Joined Aug 2012
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update!

Hi all, I have finished the intake cover and fitted the fan and thrust tube.
Thrust tube braced.
All wiring finished and tested out.
The Viper has more than 1:1 on static test with 1800mah battery.
Have completed the rear cover and ready to fit the tail and top inlet.
Cockpit completed with "pilot" waiting patiently for lift off (legoman).....hahaha. ...
Will post some pix tonight. ...." Love to build, forced to work"
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Old Dec 15, 2014, 06:46 AM
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Australia, QLD, Biloela
Joined Aug 2012
84 Posts
Got the vertical slab on. Just needs tbe finial intake an the front pieces to secure the pilot!
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Old Dec 16, 2014, 09:42 PM
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Australia, QLD, Biloela
Joined Aug 2012
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Well I knew this wasn't gunna be easy. Top intake is on, finished the to of the fuselage, battery secured. ....out to the long grass to see if it will fly.

I got the 1800mah up as far as it will go, balances at the front edge of the main intake.
#1 Hard toss at 3/4 throttle, battery slides back an takes out some supports, knocked off the hatch as it rairs up, flips over goes in nose first ........ouch. ..not a good noise. Long grass is no help if you come down straight vertical!
With the help of some tape I was able to get two more goes at it.
#2 Firm toss building speed as I went, straight out about 3. (I'm mode1 an right hand throw so I'm only worried about a fast enough for lift and level. Left hand is keeping the nose at the desired angle ) then as it flattened out I pulled back and .... nothing ....at this point I'm at full eleron back,, no response.... CG worng
Bit more nose damage but flyable. ..
#3 Same as 2, even going back to the 1300mah. Bit more tape to fix up my ...... what looks like an old prize fighters nose..
Throw # 4 installed an 850mah 45 - 90c ...same again. Couldn't get it to lift it's head. It's flying out to about 10 to 20 meters.
The pictures show the damage, it's repairable. .....
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Old Dec 17, 2014, 08:47 AM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
3,163 Posts
Well that is a little disappointing.

Looks to me like your control surfaces are just too small.

My Viper has the entire trailing edge as the control surface and it is 2" Long! So it ends up being about 1/3 of the wings as control surface.

One thing I have learned in all my experience is that if you put a big enough control surface and motor on something, you can make pretty much anything fly. This is definitely airplane shaped enough that you will get it to work.

As the great Jason Nesmith always says "Never give up! Never Surrender!"
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Old Dec 17, 2014, 09:32 AM
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Quote:
Originally Posted by SGTalon View Post
Well that is a little disappointing.

Looks to me like your control surfaces are just too small.

My Viper has the entire trailing edge as the control surface and it is 2" Long! So it ends up being about 1/3 of the wings as control surface.

One thing I have learned in all my experience is that if you put a big enough control surface and motor on something, you can make pretty much anything fly. This is definitely airplane shaped enough that you will get it to work.

As the great Jason Nesmith always says "Never give up! Never Surrender!"
She's almost repaired, a little disappointing I know but we don't learn anything if it all goes smooth. Not enough throw on the control surfaces was the major problem. CG ill be moved to the front of the top inlet
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Old Dec 17, 2014, 10:13 AM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
3,163 Posts
Make them bigger. It won't hurt I promise.
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Old Dec 17, 2014, 12:59 PM
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SE MI
Joined Oct 2004
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What happens if you just pitch her out straight power off?
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Old Dec 17, 2014, 02:11 PM
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Originally Posted by springer View Post
What happens if you just pitch her out straight power off?
Dunno mate I'll give it a try. ..

@SG
I'll give that a go if my next try fails. I have found changing too many parameters in between tests can have detrimental effects in the long run. Dont worry, I'm gunna make tbis sucker fly.....no matter what!

Thanks for your support, much appreciated!
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Old Dec 17, 2014, 03:19 PM
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United States, CO, Colorado Springs
Joined Aug 2003
6,564 Posts
Looks like the fan up above the wings and the CG?

I have a model with a shoulder mounted EDF that was *VERY* hard to pitch up with power on. The high thrust line combines with the giant power-to-weight ratio to make a killer pitch-down moment.

I put a fixed 2* up thrust diverter in the exhaust and it became a whole different airplane.

If it will glide somewhat reasonably but won't climb under power, that's probably the issue.
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