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Old Mar 16, 2011, 05:09 PM
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fishs eddy n.y.
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LAK-17FES, Interesting!

Now for those who do not have ready access to a tug or a slope and want a scale plane with the ease of electric power, here is the typical R/C solution applied to a full scale bird, the LAK-17FES http://www.lak-aviation.de/lak/fes.php I am sure you would still need either a dolly or bungee catapult to get clearance for the prop.

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Old Mar 16, 2011, 05:59 PM
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I just love it. At last we can cut the nose of our beautiful models and it's actually scale! And no need to bother with expensive, heavy, troublesome, high thrust line, CG-shifting SLS's.

For fun, I just worked out it flies at 17 watts/pound! I suppose the sailplane is just so clean and efficient it only needs that tiny input to offset frictional losses.

Anybody make a scale model of this?

Rog
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Old Mar 16, 2011, 07:51 PM
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fishs eddy n.y.
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I brought it up specifically for those scale die-hards who couldnt/wouldnt/shouldnt break the scale requirement but always wanted to try electrics. Here is your opportunity!
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Old Mar 16, 2011, 08:04 PM
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OK, soon as someone makes a decent 1/3 scale version, I am in. Cool!
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Old Mar 17, 2011, 02:26 AM
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Hhhmmmm,
I have a big LAK model and all the electrics, all I need is some white paint for the spinner and prop.........now you got me thinking again

Mike
PS what size Lipo's in the full size and do they charge off their car battery?
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Old Mar 17, 2011, 04:08 AM
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North Yorkshire UK, on a big hill facing the prevailing wind. Coincidence?
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Originally Posted by mikegbogh View Post
PS what size Lipo's in the full size and do they charge off their car battery?
Hey Mike,

They use Li-Ion rather than LiPo. 85Volts is about 26S LiIon. That'll need a big charger - probably mains.

Rog
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Old Mar 17, 2011, 10:14 AM
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The LAK site states the batteries are recharged in 4 hours, and at 85volts I would expect the charger is at least 110vac. I wonder if a few solar panels on the rear deck would allow any inflight recharging?

I seen a few pictures that show the prop is sorta inset into the spinner slightly when closed, very clean setup.
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Old Mar 17, 2011, 10:59 AM
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Wow that is awesome! Finally an electric model that perfectly emulates an original aircraft. Looking at the photos I can't figure out how they get any ground clearance for the prop!?!

Maybe they use a big dolly like we do, or the landing gear is adjustable, like a low rider LOL
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Old Mar 17, 2011, 11:13 AM
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Since they call it a sustainer, I take that as meaning they get towed in the traditional way, (tow hook located on retract) and then once in the air the nose prop has enough power for sustained flight. Might be fun to try disconnecting the towline by blipping the prop though!
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Old Mar 17, 2011, 12:13 PM
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I would expect the normal mode of launch is by winch(or tow) and being a sustainer the range and climb rate would be rather limited, but more than enough to do the job seeing all the negatives of present sustainers are eliminated. This system only added 77lbs, well below the weight of other sustainers. A larger capacity battery and larger motor up front would be interesting as well with 18m wings.

The video on the LAK site shows the controller interface showing 20 amps running it in a garage, I thought it was bad enough with the wind storm of my small NEU motors i could just imagine the wind storm from this setup in a garage!

It could get costly if ya blip too many tow ropes, but with my luck the prop would not cut the line but just act as a winch and reel in the tow plane!
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Old Mar 17, 2011, 12:15 PM
Xroadie
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Quote:
Originally Posted by s2000 View Post
Since they call it a sustainer, I take that as meaning they get towed in the traditional way, (tow hook located on retract) and then once in the air the nose prop has enough power for sustained flight. Might be fun to try disconnecting the towline by blipping the prop though!
OK...that makes sense! I guess if we wanted to try it on a scale model, we would have to have the tow release on the retract like the original! But don't try blipping the prop if they are using 600lb test spectra!!
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Old Mar 17, 2011, 12:46 PM
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Looks like a tow release hole in the spinner
scott
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Old Mar 17, 2011, 12:59 PM
Xroadie
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Quote:
Originally Posted by scottrod31 View Post
Looks like a tow release hole in the spinner
scott
No...that is for the 20mm cannon
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Old Mar 17, 2011, 02:17 PM
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Quote:
Originally Posted by scottrod31 View Post
Looks like a tow release hole in the spinner
scott
That would be a cooling air inlet, just like a RFM F5B spinner
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Old Mar 17, 2011, 02:53 PM
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I like the 20mm cannon idea better
scott
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