Espritmodel.com Telemetry Radio
View Poll Results: OK, Place your bets for fun. WILL SHE FLY?
"The force is strong with this one." 195 54.78%
"She may not look like much, but she's got it where it counts" 100 28.09%
"Negitive.... It just impacted on the surface" 24 6.74%
Pull up! Pull up!! Ba-da-boommmm! 37 10.39%
Voters: 356. You may not vote on this poll

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Old Apr 01, 2005, 02:01 PM
Jody Bradshaw
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Salisbury, North Carolina, United States
Joined Feb 2004
1,060 Posts
Chewie says.....

Arghffff!! Sniff,Sniff, Arggghfffff!!!
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Old Apr 01, 2005, 05:47 PM
Have Bluecore....will fly
GO-RC's Avatar
Arizona, United States
Joined Mar 2005
320 Posts
GOOD LUCK James! she will fly . Stay positive
Not sure on the CG maybe we have a slightly different shape. Goanna try to make some more progress on mine this weekend.
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Old Apr 02, 2005, 03:37 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
1,934 Posts
All i can say is she flew, but sustained flight was another matter.
Basically the CG was too far back, having moved it foward, it could glide rather well, but of course it ain't no aerodynamic queen.
I think the problem was the ducted fan, as i have never used one before, and on a rather unusual model, it just didn't work for me. It felt like the duct was pushing the falcon upwards as it is mounted underneath, plus the draggy airframe just didn't feel like it could get up to speed with the lower ducted fan thrust and the incorporation of a ducted fan also meaned i had to cut a lot of surface area out of the model and i am sure the duct created offset drag, causing control, trim problems.
It also tended to roll on not too many occasions for some reason. It looks like this one can roll fast!

It wasn't all a complete waste of time, i got a feel for the falcon and i can't see why it wouldn't fly. With the right power train and keeping the drag to a minium, it will fly (i think).

GO-RC, it should be noted that the falcon tended to roll some times, I had two verticle stabilzers underneath, once i had position them out so they were diagonal, i think this helped to cure the rolling problem. I am also considering much bigger topside verticle stabilzer next time, though it did do its job. Perhaps a bigger one would help to counteract the rolling?

Anyways, i have begun to install a motor at the front with a few slots to clear the prop, i have reinforced the falcon and the only apparent damage was to the manidles but they were barely broken. I am going to cover up the area cut-outs for the ducts and place the motor between the mandibles. The model also balances perfectly with the new setup.

I am doing another test flight today, but i don't know if this one will fly.

Thanks..



James,
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Old Apr 02, 2005, 05:51 AM
Registered User
icrashrc's Avatar
Indiana
Joined Jul 2003
1,064 Posts
Try to place your vertical stabs at a 45 deg angle, splayed either inward or outward. I would guess your instability in roll is mostly due to a flat lifting surface [no dihedral].
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Old Apr 02, 2005, 05:58 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
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Thanks, i will do, that is a great idea.
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Old Apr 02, 2005, 06:38 AM
Evil Plane Doer
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Westport, Pennsylvania, United States
Joined Dec 2002
1,687 Posts
My 1st tie fighter had a similar issue

http://westport-design.com/Video/Ty2.mpg
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Old Apr 02, 2005, 07:15 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
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That looks very cool! I must admit that my falcon was doing very similar rolls and had similar flying characteristics but at a slower speed. Having looked back at it, i think the ducted fan was the problem and so were lack are large verticle stabilzers. Thanks for the vid, shows that i am not alone. Though it seems to prove that the starwars ships were never intended for atmostpheric flight. I am interested in what your TIE was powered by, cheers.



James,
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Old Apr 02, 2005, 09:05 AM
Have Bluecore....will fly
GO-RC's Avatar
Arizona, United States
Joined Mar 2005
320 Posts
Well the great thing about foam is we can cut and reglue all day. Keep at it. Thanks for the cg info. I will watch It closely. Sounds like the fins are definitely goanna need to be larger. Were there any yaw issues, and was the fan powerful enough or were the main issues in control? How bout a pic.

keep up the good work!
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Old Apr 02, 2005, 10:35 AM
Evil Plane Doer
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Westport, Pennsylvania, United States
Joined Dec 2002
1,687 Posts
Quote:
I am interested in what your TIE was powered by
A CDR motor. 12 turn on 3S Kokam 340 HD cells.
Spun 12K RPM on a small 4" Graupner folding prop. It sounds so cool!
Plenty of power, just not very stable. I have a thread going in this forum but am stalled on progress due to other projects. Current plans include a much larger version with a Hacker B20L 15 4.4:1.

http://www.rcgroups.com/forums/showthread.php?t=284778

I want to get it flying by the ROTS premier. Need Motivation.
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Old Apr 02, 2005, 10:41 AM
Evil Plane Doer
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Westport, Pennsylvania, United States
Joined Dec 2002
1,687 Posts
CAD model
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Old Apr 02, 2005, 10:49 AM
Strange Plane Central
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Poway (near San Diego), CA US
Joined Dec 2000
1,883 Posts
Quote:
Originally Posted by snakeX2
That would have been my prefered setup. I think two 280 motors would do, but i don't think two Guntheres would clear each other. I expect to do the maiden today in an hour or two, much better than yesterday weathers by the way. Wish me luck!

Consider using the rotors by themselves out of a ducted fan.
They are usually steep pitched and multiblade to make the most of the small area.

http://rcguy.tripod.com
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Old Apr 02, 2005, 11:08 AM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
1,934 Posts
Wow, that is really cool, again!! I think the problem has probably something to do with the lack of any wing span, in aiding the stability. With such a powerful motor, i can't see why it shouldn't fly, but i suppose our problems are the lack of stabilisation, i say again. Why not try some clear stabilizers on it like we did with the falcon??
Anyways, glad your in the discussion, looks like we can solve these problems if we work together.

here are some pics, it doesn't look too bad and i don't care how it looks as long as it flys. I could have used the ducted fan without the duct but it didn't produce as much static thrust and it looked rather vunerable with those flimsy blades. This setup is very noisy, and i don't know how much thrust i have lots but it feels much more than the ducted fan. I think i may have reduced the drag a bit and i have moved the CG right on the predicted spot (18% of the circle I think?). I hope to test fly soon but i am starting to think perhaps my wing is too heavily loaded, it does fly rather like a brick, but it doesn't feel like a brick as it maintains control quite well. Oh well, lets just see. Cheers,



James,
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Old Apr 02, 2005, 01:29 PM
Have Bluecore....will fly
GO-RC's Avatar
Arizona, United States
Joined Mar 2005
320 Posts
Hey that looks pretty good. I think you will have much better performance this time. like your choice of fin layout, what material did you use for them?
God speed on round two.

jskrebs - great model you got there. Please continue I would love to see the larger version. The size may help stabilize her some more?
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Old Apr 02, 2005, 01:40 PM
Strange Plane Central
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Poway (near San Diego), CA US
Joined Dec 2000
1,883 Posts
Can't find the power you are using.
Motor?
# cells?

I have a flat plate delta about your size and tried S280 with no luck. S400 6V was the ticket on 7-8 cells. 10 cells was really fun.

CG is tough on these, but a pusher has aerodynamic yaw dampening.

http://rcguy.tripod.com
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Old Apr 02, 2005, 01:42 PM
Flap chap
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Most Southern England, Brighton UK
Joined May 2004
1,934 Posts
I found some old CD cases and they make perfect clear fins. The underneath ones i don't think you can get the material, some honeycomb/fibre-glass sheet.
If this don't fly, i wonder which setup next?! Cheers,
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