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Old Apr 14, 2009, 04:27 PM
tuppertn is offline
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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
Last edited by tuppertn; Apr 26, 2009 at 01:12 AM.
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Old Apr 14, 2009, 04:38 PM
Rusty-Gunn is offline
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My plans are in my blog
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This is a nice looking plane.
Old Apr 14, 2009, 05:12 PM
tuppertn is offline
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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
Last edited by tuppertn; Apr 30, 2009 at 07:18 PM.
Old Apr 14, 2009, 05:42 PM
dz1sfb is offline
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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, 05:44 PM
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"Cyclops" or "Longbow"
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Old Apr 14, 2009, 05:58 PM
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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
Last edited by tuppertn; Apr 14, 2009 at 08:04 PM.
Old Apr 14, 2009, 06:12 PM
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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
Last edited by Airboatflyingshp; Apr 14, 2009 at 06:18 PM.
Old Apr 14, 2009, 09:30 PM
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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
Old Apr 14, 2009, 09:46 PM
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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?
Old Apr 14, 2009, 10:09 PM
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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, 10:17 PM
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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
Old Apr 14, 2009, 11:37 PM
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awesome! looks like it is ready to drop bombs.... or arrows work too.
Old Apr 14, 2009, 11:41 PM
vvV FANG Vvv is online now
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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.
Old Apr 15, 2009, 11:18 AM
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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...
Old Apr 15, 2009, 12:05 PM
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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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