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 Post subject: E-flite Scimitar with jetcat p20 turbine
PostPosted: Wed Jan 11, 2012 2:51 pm 
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Joined: Wed Jan 11, 2012 6:00 am
Posts: 37
Hi everyone,
A few days ago, I converted a Scimitar to turbine. As an RC-Today Show listener, I decided to sign up and publish it here.
I like technology very much, so the idea grew that I wanted to have something with a turbine. Turbine helicopters almost only exist as scale models and I don't care how it looks like, so I did not want to spend all the money for something I don't enjoy. Turbine planes are usually very expensive, so a conventional one is not a real option.
Six month ago, I bought a Habu 32 and put 30 flights on it. After a while I had the idea that it might be possible to convert it to turbine. I was right, several other people already did it. Tamjet even offers conversion kits. As the Habu 32 is not such an easy plane to land I wanted an easier plane to get used to the turbine technology. The result can be seen in the attached pictures :D

First I flew the Scimitar about six times with the electric motor to know how it reacts, how fast / slow the landing is, to trim it out, find the throws I like and where the CG needs to be. To be honest, on my first attempt, it reached half way down the runway, did two weird jumps and crashed into the grass... I had to go home and glue it back together... It was nose heavy. I fixed this and it flew nicely as it is supposed to. I did not try the thrust vectoring.
During the afternoon I did the turbine conversion. It is incredibly simple: it takes two pieces of plywood, a sharp knife, a 500 ml lemonade bottle, a JetCat P20SX turbine with all the fuel pump, valves etc. that is needed to run it, a 2S LiPo, a BEC and 70 g of lead to get the CG right. I took out all the electric equipment and cut out some nurnies at the bottom of the white motor compartment to get enough clearance. The plywood pieces are screwed in the original place with the original screws of the electric thrust vectoring system. A few screws later the turbine is exactly where it is needed and looks good. Then comes the part where some courage is needed: cut away everything that is in the way of our trusty lemonade bottle aka fuel tank. I don't think that this really weakens the planes structure, the wings are hold on place with two carbon tubes. This excavating reveals that the first segment of the wing is hollow, this comes in handy, plenty of room to put in the receiver (it should be as far away of the turbine electronics as possible) and the air tank for the breaks (under construction).
The next day it was flying :lol:
Just what I wanted: a turbine to play with in a dirt cheap airframe (compared to the usually used jet airframes) that flies well and can easily be repaired or replaced if needed.

I have four flights on it now. It can be flown at 2/3 throttle at a pleasant speed. The sound is awesome. For the full speed, it is definitely faster than the stock electric setup. But I don't want to find out under which conditions it breaks in half, some guys with insane electric setups will certainly do this for me :twisted:

Video will follow soon.

Regards from Switzerland
Vital


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X7, NX4, X4II, TDR, Raptor 50 (Old Slimy), Logo 500SE, Helibug T-Rex 600, Protos, mini Protos, X130, nCPX, turbine Vortex 32, GeeBee R3


Last edited by Shomelin on Thu Jan 12, 2012 12:57 am, edited 1 time in total.
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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Wed Jan 11, 2012 3:40 pm 
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Joined: Mon Jul 25, 2011 11:58 am
Posts: 4965
Location: Austin, TX
Wow, that is excellent Vital! Thanks for the pictures, and I look forward to the videos!

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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Thu Jan 12, 2012 1:43 am 
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Joined: Sun Jul 31, 2011 3:43 pm
Posts: 2513
Location: Houston, Texas
Awesome!

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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Thu Jan 12, 2012 2:01 pm 
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Joined: Thu Aug 04, 2011 9:20 am
Posts: 284
<eyes wide open> THAT is cool....


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 Post subject: E-flite Scimitar with jetcat p20 turbine: The Movie
PostPosted: Sat Jan 14, 2012 3:15 am 
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Joined: Wed Jan 11, 2012 6:00 am
Posts: 37
Hi

Finding a cameraman who was not only freezing, shaking and fighting the camera for the whole flight was not an easy task and took a few attempts... Here is the result:
http://www.youtube.com/watch?v=DGwkQkoE-xg

Flying the thing is just fun and make me laugh out loud sometimes :rolling On this flight, it was the seventh, I had a sloppy front wheel -> funky take off and landing. The fixed gear was better. But now I am building in the ultra deluxe landing gears with pneumatic breaks I originally bought for the Habu 32 from TamJets. I will post some pictures of it later.

It is really nice to participate a little bit to the community I was hearing of so much through the podcast.

Vital

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X7, NX4, X4II, TDR, Raptor 50 (Old Slimy), Logo 500SE, Helibug T-Rex 600, Protos, mini Protos, X130, nCPX, turbine Vortex 32, GeeBee R3


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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Sat Jan 14, 2012 9:10 am 
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Joined: Mon Jul 25, 2011 11:58 am
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Location: Austin, TX
Love it! The sound is the best part. :D
And I see it makes a dandy hand warmer at the end of the flight too. Perhaps you could also toast marshmallows in the exhaust? ;) :lol:

We're glad to have you participating here! It's always fun to hear from our listeners, especially those in other parts of the world. :thumbup:

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 Post subject: E-flite Scimitar with jetcat p20 turbine
PostPosted: Sat Jan 14, 2012 11:32 am 
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Joined: Mon Jul 25, 2011 5:07 pm
Posts: 778
Location: West sussex, UK
Great work. Inspirational stuff

/Steve


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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Sat Jan 14, 2012 9:57 pm 
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Joined: Wed Jul 27, 2011 8:47 am
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Location: Lawrenceville, GA - Northeast of Atlanta
Even my wife thinks that sounds cool!

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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Wed Jan 18, 2012 1:34 pm 
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Joined: Wed Jan 11, 2012 6:00 am
Posts: 37
I was asked about details on how to do the conversion. I hope these pictures answer some questions.


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X7, NX4, X4II, TDR, Raptor 50 (Old Slimy), Logo 500SE, Helibug T-Rex 600, Protos, mini Protos, X130, nCPX, turbine Vortex 32, GeeBee R3
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 Post subject: Re: E-flite Scimitar with jetcat p20 turbine
PostPosted: Thu Jan 19, 2012 5:14 am 
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Joined: Wed Jan 11, 2012 6:00 am
Posts: 37
Does the turbine not melt the foamy?

No, heat is not a problem. A turbine is not a chunk of glowing metal. The inside and the exhaust gasses reach about 550 °C, but the outside of the turbine is much cooler. Well, you don't want to touch it (I did...) but the air gap and air flow is sufficient not to heat up the white plastic at all, it does not even get hand warm.
When the turbine stops, it is a different story: the rest heat inside the turbine starts to dissipate everywhere instead of being thrown outside as it gets when the turbine is running. Even the turbine itself does not like this, so after I tell it to, it initiates a shutdown sequence: first it spools up (!) a bit from idle to reach its coolest running state, then it turns the fuel off. After that the electric starter motor kicks in and spins the rotor at low rpm to ventilate the turbine until it reaches 100 °C.
The next thing to do fill up the fuel again and go for the next flight. I did five of them yesterday :-)

If you want, I can make a video only about the turbine and how it starts, runs and stops. Are you interested?

Regards
Vital

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X7, NX4, X4II, TDR, Raptor 50 (Old Slimy), Logo 500SE, Helibug T-Rex 600, Protos, mini Protos, X130, nCPX, turbine Vortex 32, GeeBee R3


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