Spirit FPV - A durable performance scratchbuild FPV platform - RC Groups
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Dec 12, 2010, 10:33 PM
Engineer for Christ
IBCrazy's Avatar
Build Log

Spirit FPV - A durable performance scratchbuild FPV platform

With all the fun I have been having running the obstacle course up the road, I decided it's time to build a new sport flyer. This one will be based on my Demon series of airplanes. The Demon series are basic perfomance oriented sport flyers. The Vampire was used as an FPV ship and is truly a wild ride to hold on at 100 mph. Now I'm looking for something more durable and with a longer flight time.

The Demon series aircraft:

Demon - 24" sport plane - my first ever scratchbuild with an airfoiled wing.
Demon V2 - 26" Park flying pylon racer
Diablo - 120mph fiberglass pylon racer
Vampire FPV - FPV pylon racer clocked at 102 mph.

This project looks promising. It will have the prop in view for a feeling of being inside the airplane. This will be built for obstacle course runs similar to this one:

FPV obstacle course slalom (3 min 39 sec)

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Dec 12, 2010, 10:39 PM
Engineer for Christ
IBCrazy's Avatar

The wing

The wing is 46" of EPP foam. It will be covered in "new stuff" rather than the previously used 3M90 and mesh tape methods. Hopefully this will be stiffer.

I decided to try a new airfoil - A USA 22. It is a bit thicker than the USA 49 I used on the Vampire and MH30 I used on the Diablo, so it won't be quite as fast. However I need the extra thickness to add rigidity to the wing. Oddly, I do want some flex in the wing. The Vampire and Diablo have a tendency to violently tip stall.

I cut the wing with my trusty 28" hot bow and the cuts came out really nice. I hope the rest of the plane comes out that well.

Dec 12, 2010, 10:44 PM
Registered User
matyou's Avatar
Awesome clip
Dec 12, 2010, 10:47 PM
Engineer for Christ
IBCrazy's Avatar

Wing covering

Well I tried the "new stuff" which is basically thick laminating film and I must say I am impressed. Although it is heavy, it sticks rather well and is incredibly stiff. I didn't know EPP could get that stiff!

Granted, putting the covering on took the better part of an hour. It was a slow task and keeping the wing flat was difficult as it wanted to curl with the covering.

First I placed a carbon rod in the wing. I cut a channel in the wing with a soldering iron with a screw for a head to get a wider cut. I embedded the carbon and glued it in with both hot glue and contact adhesive.

I then covered the wing. To avoid curling, I super heated my iron and covered the top of the wing first. I leveled any curling before going to the underside. I used the wing beds to support the wing properly while I covered the underside. I am happy with how the wing turned out

Dec 19, 2010, 11:02 PM
Engineer for Christ
IBCrazy's Avatar

Fuselage and tail made

I got some time tonight to do a little work on this plane. I made the fuselage out of a 36" long 2X2 stick of EPP. I wrapped it in the laminating film to stiffen it. While it is stiff, I might opt for another wrapping for increased durability.

The plane's tail is coroplast obtained from dumpster diving after last year's election They threw away 2 nice 4X8' sheets of perfectly good coroplast which I salvaged.

The motor is a rewound ultrafly motor. I wound it as a 7 turn WYE for abut 1500kv. This should be good for my intended 7X6 propeller. I can jump up to an 8X5 for more torque if I want it.

I am undecided on whether to make a movable rudder on this plane. I am thinking I might want a selector switch that will change from pan to rudder. I will have to put a dorsal fin down the middle of the plane to make the rudder more useful. I will make it removable for windy days.

Jan 05, 2011, 09:45 PM
Engineer for Christ
IBCrazy's Avatar

Servos installed and wing mounted

I got the servos installed and the wing mounted tonight. I used the velcro strap method as I have on two of my other EPP FPV planes. However this time the velcro strips that keep the wing from shifting are only 1/2"X2". This will hopefully make the wing shear off more easily in a crash. In my other two planes, the wing stayed put on a crash and the nose ended up crunching.

I am short a pan servo at the moment. Hopefully it will get here by next week.

I installed a modified Corona RP6D1 RX in the plane's wing. I made the MeliHK RSSI mod and will be monitoring it with my Remzibi OSD.

Currently the weight with the battery is 26 oz. I figure when I am done this plane will weigh between 34 and 36 oz AUW.

Jan 05, 2011, 10:53 PM
Former B52H Crew Chief
aerofly0610's Avatar
+1 joe satriani
Jan 26, 2011, 06:44 PM
Engineer for Christ
IBCrazy's Avatar

Complete... finally

Despite running a fever today and calling in sick, I took the time to finally complete this airplane. Good thing it doesn't require a whole lot of activity to build or I'd never have got it done.

I had a little wiring trouble, though. I burned out a camera and kept getting a short circuit on my power converter. I went through all of the wiring of my power converter and verified it was correct. I hooked it up several times frying a couple of chokes and destroying my camera. Looking at the wiring harnes I noticed the JST connector had the leads reversed Luckily the camera was the cheap $26 one. I'd have been really angry if I fried an expensive one.

Anyway, it is now ready for flight. It's raining here today, so I'll have to wait for another day to fly it. The final specs are as follows:

Wingspan: 48"
AUW: 32 oz
Motor: Rewound Ultra Fly 2505.
Battery: Single 3S 2250 mAh Lipo
Camera: Sony Chipset OSD camera.
VTX: 700mW BoB 1.3GHz
TX antenna: Skew-Planar Wheel
VRX: Readymade RC's 1.2 GHz RX
RX antenna(s): IBCrazy's "New System"
Estimated top speed: 55mph
Estimated WOT flight time: 14 minutes

Feb 02, 2011, 03:30 AM
volto's Avatar
Nice! Cant wait to see some videos.

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