I'm interested in picking up the JK Thermic 2.5m from www.arthhobby.com . This would be my first pure glider. There is a field that close to my house that usually has a high start available on the weekends. Most of the guys there use the 100" + wing spans. I would like to spend no more than $200 on the plane. From what I've heard at the guys at the field is to stick with the larger wing designs opposed to the 80" planes. Are flaps crucial in the larger planes? Can I get away with just mixing the ailerons for flaps? The radio I plan to use is the Hi-Tec Flash 5x.

Here is the link to the plane: http://www.arthobby.com/gliders/specs/thermic.html

Now that's a big glider!! (compared to my Elster 1.5)

Maybe you could program in some Spoileron with the Flash 5.
That's what I did with my Elster /Flash 5 and it seems to work.
I'll know more after I get a few more Hi-starts..

Cheers,
Rich<>

HI Fast Forward.

I have a JK Thermic that I picked up a while back and just have not gotten around to putting together. The construction on the kit appears to be first rate, as it is with all of Art Hobby's stuff.

I asked Andre the same question Spoilers vs Flaps, and he reccommended spoilerons. This thing is such a floater that flaps aren't needed. Also, I have strong opinions about flaperons, I'm not a real fan of them too easy to get yourself into trouble.

As far as this being your first sailplane, if you have lots of experience with electric assist sailplanes, I'd say go for it. If you don't, stick with a Gentle Lady, Spirit, or similar 2 meter trainer to start with until you're comfortable. You can't beat a polyhedral ship for a trainer.

Hi FF-
I am just finishing a JKThermic. The kit is a beauty, very nice quality. Mine's not quite ready to fly, but I'm aiming for a debut soon. I fly at Davis field in Sudbury, not too far for you to come over and have a look sometime.

-Tracy

I read that they recommend using Deft to cover the wing. What have you done? Is it better to use the metal gears for the aileron servos?

How much longer till completion on your Thermic, Tracy?

I know soccer season starts soon, so fly time will be limited.

I have a couple of Zagis that I've flew the heck out of. I love throwing a 8 cell 600ae pack in the Zagi and soaring around. I like burning up the sky too. I have four other planes that I've flown. It would be nice to have a clean flyer. Im all set with getting $50 batteries for a bit. Give it a year or two and prices will be cheaper. 10 cell 5000mah has a good ring.

Not sure about the Thermic but I just bought a Colibri and have been working on it this weekend. Very high quality kit.

Service from Andre at Art Hobby is first rate.

Ron

I used MinWax Polycrylic to finish the wings. Like Deft, it is a water-based polyurethane. Seemed to work OK. I am planning on using 'regular' HS-81's for the ailerons/spoilerons.
Note that HS-81's won't fit in the fuselage for the v-tail servos, my Futaba 127 receiver won't fit either. This fuselage is pretty slender and sleek. I have to go get some HS-55's and a 555 receiver to fit in the fuselage.
I am decidedly slow at building, it will certainly be well into May before this project sees any air.

-Tracy

Sounds great Tracy. Is this your first sailplane? I've looked at the calendar for the Charlesriver RC club and there is a RES contest in July. I'm hoping to pickup the Thermic this month. Then, hopefully pickup another plane for the RES contest. I would love to see your Thermic once it's completed. I astounded at how inexpensive Art hobby can sell this sailplane. Compared to other sailplanes, it ought to be twice the price. Thanks for the tips.

Jeff

Jeff-
This will be my 3rd glider, I built a 2-meter poly ship to fly off a small high-start when I was in grad school, and I am flying a 2-meter Aspire that I won at a club raffle last year. The Thermic will be my first aileron plane, and it looks a good deal 'slipperier' than the built-up poly ships I have flown. It should be a good challenge for this year.

-Tracy

I astounded at how inexpensive Art hobby can sell this sailplane. Compared to other sailplanes, it ought to be twice the price.

Sshhhh! Lets not spoil a good thing!

I fly an Elster 1.5M and the Velvia AF from Art Hobby and love them both. I have a few recommendations:

DO install 2 servos for the V-tail. You absolutely need rudder control to thermal a glider. Forget trying to thermal with aileron-elevator control only - its a waste of time. Slope flying yes, thermalling, no.

DO NOT expect blistering speed runs with this plane. It is very light, has no spar and a moderately cambered airfoil. Also, you will not be able to ballast more than a few ounces (I suggest you try this on windy days).

DO mix spoilerons for landing, I'm sure this thing will float forever. I usually hand-catch my Velvia even when ballasted with 6Oz of lead, so I'm sure it will be easy with the JK. Flaperons would be silly as the surfaces only span maybe 30% of the wing and will probably cause more bad than good. The airfoil is cambered plenty as is. (Same as the Elster BTW). You could install 2 extra servos in the wing and add Flaps if you wanted more control for Crow, launch droop, reflex, etc.

Cheers

One more thing..

Note that HS-81's won't fit in the fuselage for the v-tail servos, my Futaba 127 receiver won't fit either. This fuselage is pretty slender and sleek. I have to go get some HS-55's and a 555 receiver to fit in the fuselage.

Though light, this is still a big plane. If you're going to use HS-55's, I'd suggest you maximize the torque by using a 5-cell Rx pack, setting the travels on your radio to max (125%?) and then setting the linkages up so that you end up with the minimum necessary throw at the surface with full servo deflection. You'll need all the mechanical advantage you can get. Sure would suck to have the elevator control lock up when you're coming down from a thermal because there's too much load on them.

Cheers

Would it be best then to use the HS-81 servos? or even the MG HS-81? In regards to mixingl, I need to research if the Hi-Tec Flash 5x will allow that. Wouldn't I need to add an extra control surface to get full crow? Also would it be a good idea to add a carbon spar into the wing for added durability? My intentions is launch this on a hi-start on a regular basis. Will it be suited for this type of launch?

As far as I know you cannot operate a 6-servo sailplane with the Flash5x. You would need a radio that was capable of all the mixing. And yes, you would need to add 2 servos, cut the flaps out and reinforce the new TE with balsa. It may be possible with your radio to add the flaps but slave them together as one surface (Y-cable) and operate it on the 5th channel.

As Tclark mentioned, you cant fit HS-55s in the fuse, but no reason I can think of not to use hs-81s in the wing (as long as its thick enough).

I spoke with Andre at Art hobby about launching the Thermic. He said a regular high-start was fine, but be careful on a winch. I think it would be difficult to add a carbon spar to the wing, but I would lean towards covering the wing in clear monokote or similar if you're going to use something other than a regular high-start.

I would like to revive this thread and ask if there are any updates concerning the flying of this model or perhaps the Boar (the 2M thermal version)? Also, perhaps a moderator could move this to Sailplanes / Thermal where it now belongs.
Thanks - Jack