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Old Jan 21, 2003, 09:15 AM
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United States, NY, Spencerport
Joined Oct 2001
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RFFS for Guillow's 24" Cessna 170

What do the micro experts think of using an RFFS system on the Guillow's 24" Cessna 170. I'm planning on doing it up as an L-19 Bird Dog and flying it indoors. I'm doing my part to lighten it, but there really isn't a whole lot you can do except replace the iron wing spars with decent balsa. The completed fuselage doesn't even register on my digital fish scale, which can measure down to .02lb (approximately 1/3 of an ounce).

A friend of mine did the Guillow's Piper Cheroke using GWS Pico gear and it came out at 4oz. Too heavy! I think it would fly if I could get it into the 2.5oz to 3oz range.

What kind of motor might work on this? I think a DD GWS IPS motor might require a battery that's too heavy. I want something that'll run on a pair of 145mAh LiPoly cells.
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Old Jan 21, 2003, 09:44 AM
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dhurd's Avatar
Buffalo, New York
Joined Jan 2002
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mkirsch1
It sounds like the Guillows kit may be a bit too heavy for the RFFS-100 if your planning on an AUW of 2-3oz. The RFFS-100 is generally good for models that are less the 2oz (the miniture Wingo I had at the fly-in this weekend was 1.5oz). We do have a foam version of the L-19 Bird Dog available on our website. Give me a call or email me if your interested in the foam Bird Dog.

Regards,
Dan
DWE
www.smallrc.com
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Old Jan 21, 2003, 11:40 AM
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Jgardner's Avatar
Rochester Monroe Cty, New York, United States
Joined Aug 2002
1,577 Posts
Might work out

I would think that if the airframe weight came in at under an ounce, then the plane could work out. You may want the Seleman actuators for more power to the control surfaces. Do you have the newer RFFS with stronger actuator input?

I have been trying to build an under one oz. twin, but at the fun fly this weekend I saw that it did not have to be so light. The widget flew great at 45g.

The KP00 motor will drag around a fairly big and heavy plane.

KP00 with U80 from Dan at about 6g
RFFS at 2g
Actuators at 4g
K145 at 4g
wires, etc. 2g

All estimates are on the high side.

So you at 18g for the mechanics.

Good luck.
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Old Jan 21, 2003, 01:24 PM
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Mike Taylor's Avatar
Camarillo, California
Joined Apr 2002
4,516 Posts
I have built a 17 1/2" high wing scale model from Dumas, and it is most likely lighter than a comaprable Guillow's kit. There is about half as much to each former, the wood is lighter, etc. It came in at a hefty 50+ grams (LiteFilm isn't THAT light after all).

With the big round cowling, the KP-00 didn't cut it. I tried a custom 6:1 geared KP-based motor/prop combo from Larry Park (great little motor, very neat work, ball bearings on the shaft, matched and balanced prop, etc.) and it didn't cut it either (sorry Larry, but it will see air in another model very soon). Larry also carries voltage booster that would pep up the motors, but I don't have any experience with them....

I went to Matt Keenon for one of his 'special' motors with 6:1 gearing and a rubber model prop. This did get it off the ground and it flew OK. It is slightly larger than the KP-00/ECharger motor, and 1 1/2 times as long, low voltage.

You can sometimes get these retail from T & A Hobby Lobby (Contact: TONY NACCARATO Phone: 818-842-5062 Address: 3512 W VICTORY BLVD, BURBANK, CA ). The draw is higher than the KP-00, but still under an amp.

At the very least, you would need to gear the KP-00 down to swing a rubber model prop. The BSD actuators DO have enough poop to control a model this size, but everything must be free without any kind of drag or binding.

Good luck with the conversion, and post your progress. This is a new area of e-flight, and we all learn from others experiencecs...
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Old Jan 21, 2003, 02:12 PM
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Buffalo, New York
Joined Jan 2002
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Mike,
I suspect the reason the KP00 didn't work for you was twofold. First that big drag producing front end you had on the Mulligan and second a high wingloading. The reasoning for this is based again on the Widget I was flying this weekend that weighed in at 45grams but I never flew it above 3/4 throttle.

Dan
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Old Jan 21, 2003, 02:30 PM
Registered User
Bayville, New York
Joined Jun 2001
126 Posts
Hey Mike,
You should try the power unit from DJ Aerotech. I have this setup in my Corsair by Dumas and it should do the trick. I have still yet to recieve my covering but once i do I will test fly it. Darn shipping from Canada*#*&^#*(@! Did you even get down the runway? Keep us up on any mods you might do.
Cheers,
Brandon
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Old Jan 22, 2003, 07:26 AM
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United States, NY, Spencerport
Joined Oct 2001
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Ugh. Near as I can tell, just the framed up wings and fuselage weight almost 28g (.96oz). Looking at the fuselage, I'm now kicking myself for not hogging out the center of each former. But, my scale can only weigh in .02lb increments, and I'm sure it's not terribly accurate... It's just a fish scale.

That leaves me 11-13g for the tail group and covering if I'm to come in at 39g. Would I do myself a service by tossing the hard die-crunched tail group parts and going with a 1/16" sheet balsa stab and fin made from really light balsa? I already replaced the spars and saved a bunch of weight there. The originals seemed to be balsa that was as hard and heavy as oak.
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