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Mar 06, 2011, 10:26 AM
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Art Hobby Thermik RES 2.5m glider

I finished building this glider late last year and have finally had a chance to fly it.

There was no tow hook included in the kit, so I asked Art Hobby in Poland for one and they were kind enough to send me a nicely machined one for free. Later on I got my hands on an adjustable FVK tow hook (as used on AVA gliders) so I decided to use that instead even though it's really heavier than necessary.

I added 1 extra layer of glass to the wing center joint just to be sure since with this glider design, even though each wing panel is strengthened with carbon spars, there is no spar passing through both wing halves. It's just the skin and glass covering holding the halves together. I won't dare use a heavy winch launch with this wing.

I chose to cover the wings with Oracover film instead of the advised lacquer because I didn't think the visible glassed joints (and finger prints) would look good using lacquer, and because I wanted a high contrast and very visible colour scheme. The bottom of the wing is covered using Oralight transparent violet except for the tips which are yellow. The yellow colour is Oracover fluorescent yellow.

I chose Dymond D60 servos because of their supposed high voltage tolerance just in case I want to use a 2S lipo or A123 pack in the future.

I built the spoilers slightly shorter and slightly wider than according to the plans so that I could use my Dymond D60 servos. The servos are screwed down using one lug only. There other lug slides snugly into a slot I cut into the spoiler box which is made of 2mm balsa and glassed at the bottom. Be careful though when glassing the bottom of the servo box because it can deform the underside of the wing. Perhaps glueing a 2mm balsa floor in is safer using epoxy mixed with micro balloons. The hinge is clear scotch tape. The spoilers are each kept down using 3 pairs of tiny 2mm cubed neodymium magnets. The servo cable duct is blocked using silicone sealer so that normal pressure air doesn't leak through to the low pressure top surface and blow the spoilers open in flight.
RC glider ArtHobby Thermik RES spoiler setup (0 min 49 sec)

The finished glider ended up being tail heavy. I needed to add a chunk of 75grams of lead into the nose as you can see in the attached photos. I also added a small amount of lead into the the front of the slip on nose cone. A longer nose would have been better for this design.

The RC system is Multiplex Evo Pro 2.4Ghz M-LINK with telemetry. That's very useful for monitoring signal quality and RX battery voltage, as well as for using the vario sensor that causes the transmitter to signal rate of climb/descent with audio tones. I have 3 flight modes programmed now:
Normal: spoilers disabled
Thermal: spoilers disabled, slight up elevator
Landing: spoilers enabled on the throttle stick.

I've only been able to fly it once so far using a high start and it flew very well. No trimming was needed.

I shot an onboard video yesterday during a thermal flight:
Thermal flight with Art Hobby Thermic RES 2.5m RC glider using FlyCamOne HD 720p (9 min 30 sec)
Last edited by cmanley_nl; Mar 23, 2011 at 10:01 AM. Reason: Add spoiler detail photos.
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Mar 06, 2011, 01:44 PM
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Bud Morrison's Avatar
I just ordered the Odyssey-RES 2.7M if you get a chance could I get a closer picture of your spoiler instalation as I will need to add them to mine.
Mar 07, 2011, 04:08 AM
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Originally Posted by Bud Morrison
I just ordered the Odyssey-RES 2.7M if you get a chance could I get a closer picture of your spoiler instalation as I will need to add them to mine.
Just PM me when you're ready to build your spoilers. I would suggest hot glueing servo down without lugs and placing the servo in such a position that the horn is positioned in the center of the box so that the spoiler doesn't flex as much. Andre from Art Hobby suggested to place the servo at a 90 degree different angle to mine in such a way that the servo doesn't bear any load when the spoilers are open. The only downside in that I think is that the spoilers can't be opened (at least not accurately) in partially open positions.
Mar 07, 2011, 08:42 PM
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Maki's Avatar
Hi "Turdsurfer" you really did a great job on this model, the covering looks absolutely cool !!!, and the spoilers works very nice, this model will rock on thermiks.

I was very impressed with you telemetry sistem, in Chile, where I live, something lik that is no available. Can you give more detail of this ? which radio you use? which telemetry pack?so I can google it and maybe find a store with international shipping.

Well I wish you really nice flights and don't forget to upload a video with you flight.

Greetings from Chile,

Mar 07, 2011, 08:43 PM
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Maki's Avatar
Another question: which was the final weight of the model?

Mar 08, 2011, 04:45 AM
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cmanley_nl's Avatar
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Hi Mario,
Thanks. I'm glad you like the colour scheme. The weight of the model is approximately 850 grams. I flew it yesterday for the 2nd time and caught some thermals even though everything's flat and it's still winter here at 55 degrees North. I was able to fly continuously for about an hour and a half and reached 1500ft with it before using the spoilers to loose altitude. The RC system I use is Multiplex Evo Pro M-LINK 2.4Ghz with a vario/altitude sensor. What I find useful is that it can give me information and alarms about receiver battery voltage, signal strength, etc. The only thing I don't like about it, is that they forgot to build a cheap little earphone jack into the transmitter, so that the vario beeps don't annoy other people around you. There are other RC systems with telemetry such as Graupner, HiTec and FrSky that you can check out too. The is also no separate telemetry pack or device needed with the Multiplex system because the telemetry is built into the receiver (which means that it is really a transceiver).
Last edited by cmanley_nl; Mar 08, 2011 at 05:13 AM.

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