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Old Jan 29, 2012, 02:20 AM
Foam is where the heart is
brett.c's Avatar
Australia, NSW, Como
Joined Aug 2010
2,220 Posts
Here is my effort in depron.
I have run into the same issue I have had with all my depron builds so far..tail heaviness

I have cut the battery bay further forward and even with a 3s battery, spinner and APC prop she still needs about 20gramms to hit cg.

And its heavy too, approaching 300grams.
But I'm sure with this large wing area and 3s battery it will be rather fast and stable.
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Old Jan 29, 2012, 04:27 AM
Foam is where the heart is
brett.c's Avatar
Australia, NSW, Como
Joined Aug 2010
2,220 Posts
Update: I've moved the battery even further forward to about 10mm from the firewall and the cg is now right.

I suggest that for depron builds a short nose section, say about 30-40mm, might be helpful in attaining cg.
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Old Jan 29, 2012, 08:53 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,325 Posts
Quote:
Originally Posted by brett.c View Post
Update: I've moved the battery even further forward to about 10mm from the firewall and the cg is now right.

I suggest that for depron builds a short nose section, say about 30-40mm, might be helpful in attaining cg.
Brett,
Your bird looks really nice. Not suprised about the tail heaviness with Depron. It is a higher density material than FFF. Fortunate that moving the battery forward helped get the CG at the right spot. Yeh 300g does sound a bit portly for what is otherwise a svelt bird.

Ken
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Old Jan 29, 2012, 04:22 PM
Foam is where the heart is
brett.c's Avatar
Australia, NSW, Como
Joined Aug 2010
2,220 Posts
Quote:
Originally Posted by dz1sfb View Post
Yeh 300g does sound a bit portly for what is otherwise a svelt bird.
Paint, spackle and wbpu pack on the grams with depron.

I was going to fly it with 2s but when I put in on the scales I decided 3s would be better.
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Old Jan 30, 2012, 07:35 AM
beemerdon
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USA, NC, Charlotte
Joined Nov 2009
784 Posts
I flew mine in a pretty good breeze yesterday and it did fine. I was using a 1000mah 2-cell and got over 8 minutes easily. I tried a 500mah 3-cell and it really came alive but only a four minute flight time. I think this plane would hold an 800mah 3-cell without too much trouble, especially in the wind. Great design! Oh, mine is Depron also and I'm using the 2208-12 motor. Thanks, Ken!

Don
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Old Jan 30, 2012, 09:54 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,325 Posts
Don,
This design will carry up to a 1300 mAh 3s battery, but a 750 mAh 3s (the Rhino's fit well) lays alot flatter.

Ken
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Old Feb 09, 2012, 11:16 AM
FPV Noob
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United States, IN, Indianapolis
Joined Oct 2008
228 Posts
Ken, I need a plane to take the beach this summer. Do you think it would be possible to build the Stingray with a removable vertical stabilizer so I can pack it flat? Would this impair the structural integrity? Your designs always fly great, and I want to take something with me that I know I will enjoy. Any suggestions you can share are appreciated.
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Old Feb 09, 2012, 12:22 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,325 Posts
Quote:
Originally Posted by Sailor Jerry View Post
Ken, I need a plane to take the beach this summer. Do you think it would be possible to build the Stingray with a removable vertical stabilizer so I can pack it flat? Would this impair the structural integrity? Your designs always fly great, and I want to take something with me that I know I will enjoy. Any suggestions you can share are appreciated.
Greg,

I saw some activity on another thread about a packable plane, and actually was giving this some thought. The long slender dorsal could be problematic, so this is what I would recommend.

Build the plane as designed. Then cut the vertical fin and dorsal loose from the airframe. Then hinge the loose part on one side so that it can fold flat sideways. Use rare earth magnets in the base of the fin and the mounting surface to hold the fin in place. There should be little if any side load on the fin.

Ken
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Old Feb 09, 2012, 12:29 PM
SG Talon... Super Genius.
Lenox, Michigan
Joined Nov 2005
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Or just add some packing tape to the other side of the hinge. It is a good idea.
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Old Feb 09, 2012, 12:46 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
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You would not even have to hinge it, but I did mean to state, use packing tape for a hinge.

Dennis, get yours built yet?

Ken
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Old Feb 09, 2012, 08:12 PM
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CANNONFODDER0's Avatar
United States, VA, Arlington
Joined Jan 2011
221 Posts
If the magnets and tape don't work, couldn't you just make a wire brace without much weight penalty? (using some plastic washers or something to spread the load where they attach).

v/r,
C-F
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Old Feb 10, 2012, 07:02 PM
Foam is where the heart is
brett.c's Avatar
Australia, NSW, Como
Joined Aug 2010
2,220 Posts
Finally got to maiden mine today.
Thanks for designing such great little flyer Ken, this one will be a classic for sure.

Even though mine is a little porky at over 300grams it still flew really well. In fact, it probably needs the extra weight in windy conditions because mine was tracking really well despite the bumpy conditions.
And when the wind dropped to zero it flew like it was on rails.

Mine runs 3s and I found that it was nicest to fly at around 1/2 throttle, so 2s would be plenty. I need the 3s to hit cg.
At WOT it became a bit of a handful and tended to climb a lot. I think I need some down thrust on the motor.
I had to add plenty of expo to the ailerons because it was a bit twitchy but the elevator was just fine.

I have some more info and specs on my blog page.
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Old Feb 11, 2012, 11:47 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,325 Posts
Thanks Brett!
I know she does climb a bit under full power. For combat its been a positive characteristic as there is alot of turn and burn, bank and yank. Glad your having a good time.

Ken
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Old Feb 12, 2012, 12:03 AM
Foam is where the heart is
brett.c's Avatar
Australia, NSW, Como
Joined Aug 2010
2,220 Posts
Cheers Ken,
I took her out for some more fun and added a wee amount of down thrust. Doesn't climb so bad at higher speeds and is a lot easier to fly WOT. I also tamed down the rates a little. Hard to get them right with the older version Aurora 9. I need to do the software upgrade.

Anyway, she was holding her own against a couple of rather quick EDFs which were doing some hot laps around the park. Not too shabby for little thing powered by a 2730.

Strangely it does have a tendency to go up almost vertical if you punch the throttle from 1/2 to max. Better than going the other way I guess.

I was chucking her about at mid speed and one of the guys kept referring to it as the Swallow. I guess he's right, it does dart about like a swallow.
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Old Feb 16, 2012, 06:30 AM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,325 Posts
StingRay with landing gear

My friend Bob sent me an email with these pictures of the mod he did to his StingRay. Very Cool!

Here is the text of his email and the attached pictures;
"Ken, I thought it would be nice to be able to land and taxi the plane at the Arena, so I added the landing gear. I flew it out side yesterday on a 3 cell with the gear. It is an amazingly nice flying plane. Verticle rolls were impressive. Thank you very much for a great design and kit.

Bob"

Well done Bob! Now we need to add a rudder. This thing could do awesome flat spins with one.

Ken
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