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Old Apr 14, 2009, 03:27 PM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Build Log
LONGBOW (aka Big Geek)--72" Twin Boom Pusher..MAIDENED! **VIDEO**

EDIT 4/26: Link to a short video of the prototype maiden is in post #44.

I've been toying with a few designs trying to see what I can come up with for an FPV ship. The only real considerations are that it has to be a pusher and be capable of ~30-minute flight times. Oh, and I like big planes so I'm doing them all far bigger than they need to be. My first design was the BBAP-FPV which actually fits the bill just fine. The high thrust line makes it slightly quirky but all in all it's a good ship. However, I just wanted to try out a few other ideas.

So here's the second one. I don't have a name for it yet (suggestions welcome). This would be the twin-tail-boom type pusher in the manner of the RQ-7 Shadow, et al, although this wasn't meant to be a scale rendition of any plane in particular.

Gobs of power and aerobatic potential aren't the goals so I'm shooting for 70-100W/lb. I'll be getting that power from a Scorpion SII-3008-1220 swinging a APC 10x5E for about 275W and 49oz of thrust.

So far I've finished the airframe and installed the tailfeather linkages. Other than that it's gearless until the mailman brings me a nice box of goodies. The mostly empty airframe is right at 21.2oz (600g). I had to put 11oz into the nose to balance. Once the motor goes on I'll probably fly with something like a 3300-4500mAh 3S battery depending whether I'm carrying the camera package. I expect the AUW to be somewhere around 42-44oz. I just glide tested the airframe in the backyard and it was quite satisfactory.

Here are a few more specs:
Span = 72"
Cord = 11.5"
Wing area = 798sq.in. (5.54sq.ft.)
Wing loading = ~8oz/sq.ft.
Clark-Y airfoil

I did take a few build pics, but honestly it's not that complicated. Very basic construction from FFF and 1/2" blue foam.

Pics of the finished airframe...


kendall
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Last edited by tuppertn; Apr 26, 2009 at 12:12 AM.
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Old Apr 14, 2009, 03:38 PM
My plans are in my blog
Rusty-Gunn's Avatar
Kotzebue, Alaska
Joined May 2006
5,416 Posts
This is a nice looking plane.
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Old Apr 14, 2009, 04:12 PM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Quote:
Originally Posted by Rusty-Gunn
This is a nice looking plane.
Thanks, Rusty, but I was kinda thinkin' it was a hair on the ugly side. I'm trying to come up with a name that plays on its looks. No dice so far.

kendall
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Last edited by tuppertn; Apr 30, 2009 at 06:18 PM.
Old Apr 14, 2009, 04:42 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,334 Posts
Kendall,
I love that wing! This configuration looks like it can not but help being successful. If I may make an observation; The boom cross section looks a might light in front of the rudders. A generous radius there would help. Sharp corners tend to lead to cracks and failures.

Love to the looks man,

Ken
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Old Apr 14, 2009, 04:44 PM
Slipping the Surly Bonds
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Attica, MI
Joined Dec 2006
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"Cyclops" or "Longbow"
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Old Apr 14, 2009, 04:58 PM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Quote:
Originally Posted by dz1sfb
The boom cross section looks a might light in front of the rudders. A generous radius there would help. Sharp corners tend to lead to cracks and failures.
The tail booms have a 2mm x 6mm CF strip running their entire length--from where they attach to the wing all the way back under the H-stab. Should be enough...I think.

Quote:
Originally Posted by dz1sfb
"Cyclops" or "Longbow"
Oooooh...Longbow. I like it. Can I use that?

kendall
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Last edited by tuppertn; Apr 14, 2009 at 07:04 PM.
Old Apr 14, 2009, 05:12 PM
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B'ham UK
Joined Oct 2005
2,990 Posts
Nice, It reminds me of some real working planes convergent evolution in action, low wing is a bit unusual but I like it Note the LE slots on the Heston Observer
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Old Apr 14, 2009, 08:30 PM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Adding some build pics...

Like I said, the construction was very straight forward. No wheels to re-invent.

It took me a couple of tries to get a satisfactory Clark-Y as I'd never built one (always gone with KFm3's before this). I decided not to go through any ridiculous antics to get exactly 11.7%. Just using foam spacers I got 11%...close enough. The LE profile is a bit too semi-symmetrical looking to me. I was a bit worried since the incidence is set parallel to the flat part of the lower surface, but it seems to glide just fine so far. I hid a KFm3 strip inside the wing because it adds very little weight but a good deal of strength and torsional rigidity.

The tail booms are one layer of 1/2" blue foam with the control rod guide and CF strip embedded in the foam and sandwiched with a layer of FFF. The H-stab has a KFm2 with a 1/8" CF spacer under the step.

The twin rudders are connected with a simple music wire linkage. Z-bends are attached to the rudders' TE using the two halves of a Du-Bro pin hinge. A little heavy perhaps but still better than using two rudder servos.

I'm going to maiden without LG and see how it goes.

kendall
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Old Apr 14, 2009, 08:46 PM
Registered User
Connecticut, USA
Joined Oct 2008
322 Posts
Excellant craftmanship kendall.... I like the design alot. I have a twin boom swept wing on the back burner myself so I am a big fan of twim booms in general.... Good luck with maiden....How about calling it double trouble?
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Old Apr 14, 2009, 09:09 PM
Slipping the Surly Bonds
dz1sfb's Avatar
Attica, MI
Joined Dec 2006
10,334 Posts
Quote:
Originally Posted by tuppertn
The tail booms have a 2mm x 6mm CF strip running their entire length--from where they attach to the wing all the way back under the H-stab. Should be enough...I think.


Oooooh...Longbow. I like it. Can I use that?

kendall
I realised after I posted that the booms were more robust than I initially thought after a closer look at the pictures. With the added CF sounds plenty adequate.

You like Longbow, its yours. I just tried to come up with what came to mind.

Ken
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Old Apr 14, 2009, 09:17 PM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Quote:
Originally Posted by dz1sfb
You like Longbow, its yours. I just tried to come up with what came to mind.
I like the medieval theme and the allusion to strength and distance. I went back and Wiki'd other medieval weapons to see if anything sounded good (and I hate just blatantly stealing your idea) but nothing tickled my fancy (so unscrupulous thievery is back as an option).

Cool. I'm changing the name of the thread...

Thanks, Ken!

kendall
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Old Apr 14, 2009, 10:37 PM
Yummy cheese
enduro_man996's Avatar
Earth
Joined Mar 2009
285 Posts
awesome! looks like it is ready to drop bombs.... or arrows work too.
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Old Apr 14, 2009, 10:41 PM
Formerly bUd~Fokker
vvV FANG Vvv's Avatar
Australia, NSW, Eurongilly
Joined Aug 2008
2,039 Posts
I looked at your username and gave the plane the name the Turpentine! Or perhaps the Turpentine Twin :P

Longbow does sound cool though

How about the Balista for a medieval type name!

Nice looking deign, i like twin booms like on the DH Vampire the worlds sexiest plane.
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Old Apr 15, 2009, 10:18 AM
Yummy cheese
enduro_man996's Avatar
Earth
Joined Mar 2009
285 Posts
I remember now... I thought there was a production Longbow.... It is the Apache Longbow... a version of the AH-64D.

Not that... it matters the little AH isn't made out of foam... so it sucks

yours is much cooler...
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Old Apr 15, 2009, 11:05 AM
Postcards From The Purple Edge
tuppertn's Avatar
United States, OK, Sand Springs
Joined May 2007
3,919 Posts
Quote:
Originally Posted by enduro_man996
I remember now... I thought there was a production Longbow.... It is the Apache Longbow... a version of the AH-64D.

Not that... it matters the little AH isn't made out of foam... so it sucks

yours is much cooler...
Hehe. I didn't know about that one, but an AH-64 is all big and heavy and stuff. The best second choice I could come up with was Falchion--pretty cool too, but I still like Longbow better.

kendall
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