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Anyone done anything this stupid before???

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Anyone done anything this stupid before???

Old 07-23-2003, 11:39 PM
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3DFanatic
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Default Anyone done anything this stupid before???

THE PLAN:
To build a model of about 40" (Delta wing) featuring a vertically rotating EDF (probably about a 400) in the nose and 2 fixed EDF (probably 400s too) in the rear pointing down.

THE REASON:
A vertical takeoff electric jet. The nose fan rotates up 90. The 2 rear fans are connected (and use differential thrust for roll control in hover flight mode), the nose is independant of the rear and uses its throttle position for pitch in hover mode. You can also angle the nozzle forward or backward to maneuver in hover mode.
To transition between hover mode (which I've dubbed HFM for hover flight mode) and normal (NFM), you slowly rotate the nose horizontal while increasing the throttle and decreasing the aft fan throttle.

ANYHOW, has anyone done something like this before? If so, would you mind uploading some pictures of the structure and flight control mechanisms for me?

Many thanks,
Old 07-23-2003, 11:43 PM
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rocd
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Default Anyone done anything this stupid before???

I don't know anything about rc planes but your idea sounds a lot like the marine corps new osprey. look it up. you may get some ideas from it.
Old 07-23-2003, 11:58 PM
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Default Anyone done anything this stupid before???

Hopefully my design won't crash as much
Old 07-24-2003, 12:14 AM
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rocd
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Default Anyone done anything this stupid before???

At least you wont have to worry about people dying if it does (hopefully!!!).
Old 07-24-2003, 05:53 AM
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Default Anyone done anything this stupid before???

I just have to worry about a burned up investment...

Oh well, it's an experimental aircraft, right? X-planes alway shave bumps along the way.
Old 07-25-2003, 01:57 PM
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bratcher
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Default Anyone done anything this stupid before???

Look at the first picture in this thread - looks electric (not positive) but it's definitely VTOL:

http://www.rcuniverse.com/showthread...865&forumid=26]
Old 07-26-2003, 05:01 AM
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spiralscratch
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Default Anyone done anything this stupid before???

Nope, that's a turbine on a pivot. Pretty crazy.

I've had the same basic thoughts about a VTOL wing, but I think it would be too heavy with the additional motors and larger batteries required to drive them all.
Old 07-26-2003, 06:24 PM
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SigKavalier
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Default Anyone done anything this stupid before???

It could be done, but would be very costly. First the best and only way to go is brushless with li-poly cells.
So let's say 3 wattage fans with cut-down kyosho rotors or 3 vasa fans. Running Hacker B20's on 3 thunderpower li-poly packs.

That's $100 worth of fans, $500+ worth of motors, $150+ worth of li-poly's, and you need 3 brushless ESC's.

Most brushed motor EDF setups can't even produce a 1:1 thrust ratio without an airframe. Just fan, motor, esc, and batteries.
The new li-poly's and a brushless will get you much closer. Plus the speed 400 and smaller brushless motors can use li-poly's at a much lower cost.

If I were to try it I would use 2 large geared motors turning two ducted props. Which produces much better static thrust on less juice than a ducted fan. Like 2 Razor 300's mounted into two GWS gearboxes swinging 10x7 APC props. The duct would be a simple airshaped ring around the prop which prevents the normal losses at the prop ends. Actually in a duct would probably need to run smaller 9x4.5 or 9x6's.
Then in the nose I would use a helicopter tail rotor on a gyro to control pitch. The Razor motors are about $70 a piece, and you can use $48 thunderpower li-poly packs for 15+ minutes of power. You also save about 6oz of weight over normal packs.
Old 07-27-2003, 05:57 AM
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Default Anyone done anything this stupid before???

Rotating turbine

I was planning on using regular old 400 fans with LiPoly cells. Each fan can get 12>ounces thrust.
If I keep the all-up weight under 33 ounces, it might just barely limp around the sky....
Old 08-20-2003, 11:38 PM
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Default Anyone done anything this stupid before???

Ok first add up the weight of all the motors, fans, controllers, cells, servo's, and receiver. Round up for safety, and the linkages wire etc.
Then get the airframe weight.
You need better than a 1:1 thrust to weight ratio to take off vertically. Otherwise at 1:1 you'll get a neat little hovercraft that'll get maybe an inch off the ground.

Not trying to rain on anyones parade just being realistic.
Old 08-21-2003, 12:33 AM
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Default Anyone done anything this stupid before???

I figured my equipment weight to be in the neighborhood of 15-20 ounces. That gives me 10-13 ounces to build an airframe because three of Watt-Age's 400 fans put out a total of around 36 ounces.

If I use LiPolys and lots of lightening holes, she might fly. In either case, I'll end up with a EDF model. I can jsut take the wing fans out and have a horizontal bird
Old 08-22-2003, 09:44 PM
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Default Yes!

If you haven't already seen it, check out Doc Watson's beautifully-crafted X-35 project (electric VTOL and transition) at http://www.awatson1.fsnet.co.uk/

This man is a craftsman.

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