Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Project Voodoo Build Thread

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Old 04-02-2014, 02:12 PM
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Lomcevak Duck
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Default Project Voodoo Build Thread

I've not been very active in R/C in the past several years, but now that I've bought a house and built a room just for the planes, it's time to build!!!

A few years ago, I called up Jett and had an engine built. I thought I would have the time to build, but then I changed jobs, moved five times, and all but abandoned the hobby. That dark chapter is over and I'm ready to fly. I started with cutting a few foam cores that were 6%-8% in thickness, double tapered. I ended up tossing out most of those attempts because I just didn't like the way they were coming out. So I've decided to go in a much easier and quicker direction and modify an existing design just to get something in the air. I'm calling it Project Voodoo without good reason. It sounds cool, I guess.

Engine: Jett BSE .56LX F.I.R.E.
Airframe: Modified Hobbico Viper RTC
Planned modifications: Clip wings to 40" span, no landing gear, modify fuselage to accept a rear exhaust and tuned pipe, built-up 3/4 cowl, significant carbon fiber and fiberglass strengthening.

I started with the wing. While the fiberglass is setting on it, I started on the fuselage. I cut out the shape of the tuned pipe on the top, then put in some insulation foam. I used a dremel tool to shape out the curve, then I put in fiberglass. When it has cured, I'll go back and get the foam out with acetone.







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Old 04-02-2014, 02:58 PM
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You're getting off to a good start..!
Weston UK had a .35 sized Voodoo that I saw a photo of a few years ago. I built a .061 powered version of it.
It's a pretty cool looking model the way Weston presented it.
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Old 04-04-2014, 06:09 AM
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I thought I had acetone for the foam, but I guess that was lost in my last move, so I used my heat gun to remove the foam.

Here's how the underside of the tuned pipe tunnel turned out. I think there should still be plenty of room for my radio gear and fuel tank.
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Old 04-04-2014, 10:15 AM
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Good job...!
Nice to have you back and see that you're itching to play with our speedy toys again.
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Old 04-04-2014, 11:43 AM
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Thanks, CP. It's been too long since the last time that I put something fast in the air. I only flew one time last year, maybe twice the year before? I broke out my Kaos again a few weeks ago and it put the fever back in me.

And I have a little girl on the way. I feel like that's a good reason to start flying and building again.

Is 6 months too young to buddy-box? (I keed, I keed...)
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Old 04-04-2014, 02:13 PM
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Anything that has to do with this hobby is like bug spray to most females..but there are a few outstanding exceptions. A local teenage girl with about a year's worth of training won the biggest Fast Combat contest in the world [The Bladder Grabber] a few ago. She was just average size, very pretty and very talented. Those Nelson .36 powered planes pull like rottweilers, too. I have to lean back while flying them, but this girl handles them like it's just a cell phone or a bottle of coke in her hand.
There was also a girl from the USSR who competed on the world stage..Svetlana....her last name escapes me now. I think she did Precision Aerobatics and some FAI combat on the side.
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Old 04-05-2014, 10:40 AM
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The fuse and pipe tunnel reminds me of a Doddger I started about 12 years ago. The fuselage and V-tail are ready to go, so at least the first 4 hours of work are done. Mine has a ST-X .45 on a firewall mount. Maybe next season..
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Old 04-05-2014, 05:40 PM
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I think for this one I'll go with a conventional tail rather than the V tail.

I would do the V tail if I thought I could hide the control horns, but I'm not sure how to do that. The fuselage is awfully small back there.
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Old 04-05-2014, 05:58 PM
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It either takes a lot of room for individual clevises, or you can put the individual torque rods from each ruddervator onto a single specially made clevis. This idea still requires room to operate
The aft end of the fuselage needs to terminate well aft of the linkage, so that the fuselage has enough width where the linkage is at.
The single clevis method puts the linkage into a bind just a few degrees either direction from zero trim so it's kind of hokey..I did use this on a 1/2A plane, but my first attempt put so much stress on a nylon clevis that the clevis broke while I was finalizing the servo hookup and was getting ready to close off the aft end of the fuselage. If it wasn't for a friend INSISTING that millions of electric power racers do it with a single clevis on their small racers, I would have thrown in the towel.
Funny how when you ask pylon racers about the advantage of V Tail vs conventional, most I ever talked to say that there is no noticeable difference....but most of them run V-Tails now.
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Old 04-05-2014, 06:16 PM
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This model will have a high thrust line [compared to where the wing sits.
Hand launch models like this at full power tend to dive for the dirt right after release. The high thrust line just makes the nose rotate downward. You can hold up elevator during launch and risk a stall and really wobbly launches.
All I know is that I've built a few P-51s and all 3 tended to have this problem.
One was .049 powered 24 inch span, another was 1/12th scale with OS.15 and the most recent was a Top Flight model with OS.32
The problem was worse with the engines inverted, which of course placed the prop at the highest point possible. The 1/12th scale OS .15 model had the engine upright so the thrust line wasn't high enough to be a real problem but you could see the plane tend to zoom down a wee bit after release. The .15 model also had generous dihedral, which effectively lowers the thrust line as well.
The OS.32 model could have used more dihedral...that plane was a real ***** to hand launch and not because it lacked the power.
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Old 04-06-2014, 07:20 AM
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Yeah, I don't think I want to mess with significant modification of the fuselage back there. The V tail would really only be for appearance, as I don't think it makes much of a difference in drag either way.

That, and since I'm not going to have a rudder, I can save a touch of weight by having only one servo.

I don't think I've ever hand launched a low-wing plane before. Lots of high wing, profiles, and deltas, but nothing quite like this. I think I'll put the gear on for the first couple of flights. That should give me a chance to play with low-speed high AOA up high before I try to hand launch.

Last edited by Lomcevak Duck; 04-06-2014 at 08:17 AM.
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Old 04-06-2014, 09:43 AM
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That sounds like a good plan...to have removable gear. You could also leave the gear off and launch it from the top step of a 12 foot step ladder.
I'm not saying this plane's layout is extreme enough to cause any trouble with hand launching...........but the mystery of why I had trouble with some low wingers didn't dawn on me until it was too late for the OS.32 powered model. Otherwise, if it survived the launch it was a good flyer.
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Old 04-06-2014, 10:09 AM
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Removable gear is easy on this design. The gear blocks are already installed in the wing.

I know a lot of people (particularly pilots who actually race) dislike this plane. I'll agree that it isn't the latest and greatest, but I love the Hobbico version of the Viper. I think this will be my fourth one. Once you learn where the weak spots are and what needs a little help, it's a pretty quick sport plane that is easy to get in the air without a lot of fuss.
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