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Twin Boom Pusher

Old 03-05-2005, 06:38 PM
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gbdvorsky
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Default Twin Boom Pusher

I've been lurking around various sites in search of a pusher design for me to use a bunch of spare parts I had lying around. In my search for a design, I ran across the Pioneer UAV which is used for reconnaissance by various branches of U.S. and foreign militaries. I recently got into using coroplast, so I thought I could add a modified Debonair wing to a PVC fuse and twin boom tail made from aluminum angle. The design isn't exactly to scale, but it does bear some resemblance to it's "older brother". I used the SWAG method to determine the tail and vertical stabilizer dimensions, and finished her up earlier today. I balanced it on the spar, and it took a LOT of weight up front (my guess is 12-16 oz.). It's powered by an EVO .46, with an 11 X 6 prop, so I was really concerned about power.

Since the weather today was decent, I headed out to the field for her maiden. A real pleasant surprise ... she flew GREAT!

I'm in the process of cataloging the various dimensions and weight as I was guessing a lot during the construction. For anyone who is interested in aerial video/photography this might a great ship given the available payload up front. For anyone interested, I'll be providing additional details soon.

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Old 03-05-2005, 09:34 PM
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DLSmith2
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Default RE: Twin Boom Pusher

Great job! That would make a great camera platform! Looking forward to more information on the measurements, build, and how it handled in the air!

Blue skies,

DL
Old 03-06-2005, 09:56 AM
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Smooth Spanky
 
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Default RE: Twin Boom Pusher

Gbdvorsky:
Hey, great looking SPAD, I really like it!! I think it's got a pretty strong resemblance to the UAV. The tail feathers remind me of a Warthog for some reason...love it.

Would appreciate any details you can provide. This looks like a great next project.

Old 03-06-2005, 10:46 AM
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gbdvorsky
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Default RE: Twin Boom Pusher

I'm not real proficient with the various drawing programs out there, so it will take me awhile to get you guys something presentable. For the time being though, I can give you a few more specifics with photos.

Fuselage - 4x4 PVC sleeve used to cover wood fence posts. I got an 8' section from Menards for about $11. The fuselage is 32" long. I built a lite ply hatch for the front. I also added about 20 2" lightening holes then covered with some scrap Ultracote I had.

Wing - I built the wing in 2 sections similar to a Dogfighter wing - 4 mil on bottom, 2 mil on top. The span is 64" with a chord of about 13". The ailerons are 2.5", and the spar is 4" back of the LE.

Tail - Made from 3 pieces of 4 mil. The horizontal stabilizer is 22" x 8.5", and the 2 vertical stabilizers are 8.5" x 10". The three pieces are held together using two pieces of 6-32 allthread. There's no rudder, just elevator.

Tail Booms - Two pieces of 1/2 x 1/2 aluminum angle 31.5" long. When I was assembling the wing, I CA'd lite ply and two small poplar strips for the servo mounts and to serve as mounting points for the tail booms. I used thread inserts for the hard points, but blind nuts would work as good if not better.

Unfortunately, there's nothing but dead weight up front. I moved the fuel tank out under the wing so that the CG is least affected as it empties. But that's why I say it would be a great camera platform - you NEED to put a bunch of junk up front to balance.

Since I don't have a decent scale, I'm guessing that it weighs between 6 and 7 lbs. That would put wing loading somewhere under 20 oz./sq. ft. The wing loading is probably something more than your run-of-the-mill trainer, yet it is super stable in flight. It does lose a little altitude in the turns, but without a rudder, they can't be too coordinated. Approaches are fast and flat - ground clearance for the prop is an issue, so a high nose up attitude isn't desirable anyway. I'm using a receiver that I borrowed from another plane. As soon as I get the new RX I'll be able to add flaperons to slow the approach speed.

As they say, a picture is worth a thousand words so here are a few more...
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Old 03-06-2005, 09:30 PM
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I.C.O.N.
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Default RE: Twin Boom Pusher

It is bigger then I was thinking initially.

Kewl lookin plane!

it is awesome to just think of a plan and then make it fly... ...


still waiting to experience that for myself.

Thanks for sharing!

If you have some rough sketches I may be able to put them into cad for some plans if that's ok.

Let me know.
Old 03-07-2005, 08:53 AM
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Default RE: Twin Boom Pusher

Gbdvorsky:
Thanks for the pictures, these always help a bunch. If you could take any more, it would really help out a ton and I think I could get by on just this info alone. Sometimes placing a ruler in the picture helps to just 'TLAR' the dimensions.

I was a bit confused on the one picture showing the servos in the fuselage, I could't figure out what the larger servo was for. It appears that this is used to control the front wheel...is this correct? Could we get a photo of the bottom of the plane showing this detail?

Also, although it doesn't show it, it looks like you must have 1 servo per aileron. Could you also show some pictures fully assembled from from the bottom?

Would you suggest using a .46 engine, or if you had to start from scratch would you go bigger?

I've only built one-piece 4 mil wings so far, can anyone direct me to where I can learn the 2mm/4mm process?

Again, great looking plane, I'd really like to copy your design.

Thanks everyone!
Old 03-07-2005, 10:15 AM
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Captain351
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Default RE: Twin Boom Pusher

That's Pretty Cool.

Some pictures of the tail please.
Old 03-07-2005, 10:24 AM
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gbdvorsky
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Default RE: Twin Boom Pusher

I.C.O.N. : You're right about the size, it is much bigger than the pictures indicate. If you're willing to draw up plans, that'd be great. I'll try to hand draw some rough sketches for you ASAP. Thanks.

richiekolp: That's why I was initially worried about the .46 and having enough power. We fly off of a 250' asphalt runway, and it uses most all of it to get airborne. Although I haven't tried it, I don't think a grass field is an option. After flying again yesterday, I'd recommend a .61, but would need a taller landing gear so I could swing a bigger prop. Once airborne it really flies nice, I'd prefer just a bit more power for takeoff.

I had a bunch of spares, so the plane is truly a hodgepodge of parts. You're correct, the larger servo steers the nosewheel -- ground handling and steering on takeoff is actually really good. The micro servo actuates the throttle. I tried to get as much up front as possible for balance. What isn't shown are some old 8-cell battery packs that I'm using for weight in the nose in addition to all the mechanicals you see in the pictures.

There is one servo per aileron. The one picture of the underside shows the servo for the right aileron and the elevator servo installed on the underside of the wing next to the boom. As for the 2 mil/4 mil process, I'd go to most any of the various SPAD sites and search on "Dogfighter" -- the plans describe the method used for constructing the wing. BTW, I ripped the spar out of a single piece of poplar, but you could easily use yardsticks to accomplish the same.

I'll try to get some more pictures up soon.
Old 03-07-2005, 06:24 PM
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Default RE: Twin Boom Pusher

gbdvorsky, very nice I have just 2 questions,

would you be interested in making this plane as an ARF and selling it to others ?

what could be done to it to make it leave the ground quicker, and ROG off of grass?
Old 03-07-2005, 07:34 PM
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gbdvorsky
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Default RE: Twin Boom Pusher

As promised earlier, here are a few more picture to show additional elements of the construction.

RC-FIEND: Haven't really thought about your first question. I've been too busy de-bugging/tweaking to start thinking about producing in any kind of quantity. An interesting thought nonetheless. Let me continue beating on my "test mule" to see what sort of improvements might be necessary. I.CO.N. said he'll draw up plans as soon as I can get him some rough sketches -- I hope to do that in the next few days. But, it's possible I could do a few "one-offs". I haven't tried to fly off of grass yet ... it might well work as is, but ground clearance is definitely an issue. However, a .61 with a taller main gear (to swing an ample sized prop) and maybe slightly larger tires, and I'd guarantee you good results.
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Old 03-07-2005, 09:47 PM
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Default RE: Twin Boom Pusher

gbdvorsky:
Thanks for the extra pictures, that really helps out. Now for my stupid question of the day: how do you set up a pusher configuration? I presume the motor will only run in one direction, so is there a special prop for a pusher?

Thanks for the help.

Smooth
Old 03-08-2005, 12:09 AM
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gbdvorsky
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Default RE: Twin Boom Pusher

richiekolp: There is no such thing as a stupid question in this forum, and especially not in this thread. There is a special prop required. I happen to be using an APC 11 x 6P (that's how you'll know it's a pusher - and its stamped on the prop). I lucked out as my LHS must have either anticipated demand, or, the checked the wrong box on the order form. Anyway, the right size for my engine was available locally, but they're readily available through Tower, Horizon, etc.

I'm a big fan of DuBro's Aluminum Spinner Nut, so it makes a real clean installation without the need to make new cutouts in a spinner for the different profile of the prop.
Old 03-08-2005, 05:31 PM
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Default RE: Twin Boom Pusher

gbdvorsky:
Thanks for kind words and the info on the pusher prop...excellent. Funny you should mention the Dubro alum spinner - I just bought my first one a week ago because I became tired of wrestling with the lousy plastic designs I came across. When I saw they came anodized in various colors I was sold.

I never fail to learn it last one useful thing a day in these threads!!
Old 03-10-2005, 06:58 AM
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Default RE: Twin Boom Pusher

MAN! I thought I had the idea first!!!!!!!
Great job, Im working on a twin Boom pusher as well Im using an OS 32SXH heli engine.
glad to hear it flies good!!

BTW thats the heli engine mount straight off of an old concept 30.
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Old 03-10-2005, 12:52 PM
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MrGreenSpeed
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Default RE: Twin Boom Pusher

Here is a thread I just found, it's almost a year old, Villa posted about His twin boom pusher/puller Spad.
http://www.rcuniverse.com/forum/m_18...tm.htm#1806004
Old 03-16-2005, 08:49 AM
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Bryan H.
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Default RE: Twin Boom Pusher

W4,
I like your design, it definitely takes care of the prop-ground clearance problem. Do you forsee any problems with stress cracking at the corners of the notch for the motor?
Old 03-16-2005, 10:10 AM
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Default RE: Twin Boom Pusher

Here are more recent photos of my Pusher/Puller. Engines .28 Magnum, 48 span. Because of the winglets, it can take off (on a good day) on one engine. Weighs about 6.5 pounds. Only a SPAD can be mistreated this way. Takeoff is at 100% stall. The elevator is used like a jack. Very exciting. Will knife edge all day.
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Old 03-16-2005, 06:45 PM
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Default RE: Twin Boom Pusher

I think you are in first place for creativity. Dude from russia has to be second though he has some decent coro fuse planes.

Good Luck

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