Handlaunch a Thermic 36?

Handlaunch a Thermic 36?
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Handlaunch a Thermic 36? - 1/27/2004 6:04:25 AM

O2man

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Rummaging around in my files today, I found some old plans for a Jetco Thermic 36. Wow! does this bring back memories!

Got to thinking----I wonder what it would take to make a handlaunch out of it. I certainly would have something that is unique!

The tail seems it might need a little more area. The airfoil is only 1/4" thick, but as a R/E it should be ok. If a different airfoil would help, which one to use and keep the "vintage" look?

Anyone have thoughts about what to consider? Techniques? Materials? Modifications?

< Message edited by grandpa -- 1/28/2004 12:54:59 PM >

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RE: Handlaunch a Thermic 36? - 12/31/2004 1:39:32 AM

FlyNow

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Hello,

I built and flew the Thermic 36 when I was a boy. I loved the way it flew. It would float like a feather. That was before I got into RC flying. The wing was a little fragile. I would beef up the outter section where it joins the main wing. The outter joint was weak. I never had any trouble with the tail feathers, but I only flew it as a handlaunch free flight glider. I never tried to add RC gear back then. Today, it would work pretty well.

I have been looking for the Thermic 36 kit for some time. I would love to get a copy of the plans and scatch build one. Is there any chance I could get a copy of your plans?? Also, you wouldn't know where a kit would be available, would you??

Thank you for the consideration.
Frosty Arnold

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RE: Handlaunch a Thermic 36? - 12/31/2004 3:52:46 AM

SoCal GliderGuider

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This one?

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RE: Handlaunch a Thermic 36? - 12/31/2004 6:39:05 AM

O2man

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I do have the original plans I used to build mine. I can get them copied locally if you like.

As for the kit, I don't know of any source. Coos Bay lumber knows the Thermic 72 and has plans for it available. I think at one time he was kitting it. I'll find his address and website for you if you like.

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RE: Handlaunch a Thermic 36? - 12/31/2004 7:47:40 AM

BMatthews

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For free flight like speeds thin is where it's at. It's an all balsa wing so strength is not going to be an issue as long as you provide a clean javelin like launch.

Or you could use a light duty high start. I'm launching my 50 inch, 12 oz HLG with a micro start that uses a 12 foot loop of 1/4 inch flat rubber model rubber and about 60 to 80 feet of 10 lb test monofilament nylon line with a 5 inch square flag instead of a heavy and draggy parachute. This arrangement takes up my glider like a shot and with much wind at all it'll lift the rubber clean off the ground while still hooked on such that I have to push down slightly and zoom it off. All this with about a measley 16 oz of pull on the line at max stretch

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RE: Handlaunch a Thermic 36? - 12/31/2004 4:38:52 PM

SoCal GliderGuider

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I stumbled across a very good copy of the original plans for the Thermic 100. Three sheets. Two different fuses. Zaic's penmanship is so crisp you would think he just finished them yesterday.

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RE: Handlaunch a Thermic 36? - 1/1/2005 12:11:16 AM

O2man

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Hey SoCal GliderGuider!

Are you interested in providing copies of the Thermic 100? I'm glad to pay the cost and postage if you are. I always wanted to build it back when, but the time, classes, two kids, and cash flow got in the way.

The plans I have for the Thermic 36 show a built up fuse and wing. The plans you posted are solid. did you ever get a chance to fly the one you posted?

< Message edited by O2man -- 1/1/2005 12:12:37 AM >

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RE: Handlaunch a Thermic 36? - 1/1/2005 3:37:55 AM

SoCal GliderGuider

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It's a page out of Frank Zaics 1943 Model Glider Design book. I've noticed, as with the Thermic 100, there were serveral redesigns of the same plane over the years. I'll see what I can find. As to the Thermic 100; I have to get a price on plan duplication and postage and get back at you.

< Message edited by SoCal GliderGuider -- 1/1/2005 4:16:30 AM >

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RE: Handlaunch a Thermic 36? - 1/1/2005 4:59:08 AM

Silvaire

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Now this is my kind of thread - probably because I love the look of Frank Zaics beautiful gliders! He was truely an artist. I do not think that anyone made more beautifully drawn plans either.

The Thermic 36 kitted by Jetco in the late50's/early 60's featured a built up wing with a flat center section and a built up sheet balsa fuselage. It is actually a Bill Siegle design, and is not one of Franks (being designed after Frank and the company he founded parted ways). The weak point of the Thermic 36 is that there is no spar - with only the leading and trailing edges to provide wing strength. This "shortcoming" is in all the Zaic designed Thermic series gliders up to and including the Thermic 50 variations. This is not an issue if you are towline flying with a light weight free flight floater (as these were originally designed to be flown). With hand launch or high start it is a much different matter!

If you like the look of the Thermic 36, you might like to take a look at a Thermic Traveler (not a Zaic design, but obviously inspired by his style). It is a more recent design that looks like a Thermic 36 but has a 76" span. It was designed to be either an electric or a pure glider. It was originally kitted by Electric Model Design, and later by Aveox.

Both the Thermic 36 and Thermic Traveler kits show up on ebay from time to time.

Skybench Aerotech currently has a short kit listed for the Thermic 100. It is the post war "full fuselage" version. For modern R/C flying, the Thermic 100 has a rather weak wing. It has an undercambered airfoil and a shallow stick type main wing spar. An updated short kit by Hobby Horn had an improved full depth web type spar, but kept the original airfoil. The Hobby Horn kit included plans for both the full fuselage and the early pod and boom style fuselage. I do not know if the Hobby Horn kits are still available, but if I were contemplating building a Thermic 100, I would certainly want to build one with the improved wing...

Arlen

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RE: Handlaunch a Thermic 36? - 1/1/2005 5:35:22 AM

O2man

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Thanks for the information, Silvaire. I'll check out Skybench and Hobby Horn.

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RE: Handlaunch a Thermic 36? - 1/1/2005 6:08:47 AM

SoCal GliderGuider

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Hobby Horn and Midway Models were the same business. Might try www.freeflightmodels.com as he seems to have picked up on some of the older designs that Hobby Horn marketed.

Notice that the name on the above Thermic 36 is John Zaic. Could be that this design was reintroduced as a kit later thus you see the build up wings and fuse. Same with seeing the truss structed fuse for the Thermic 100 rather than the balsa block and tail boom of the earlier design.

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RE: Handlaunch a Thermic 36? - 1/1/2005 7:11:30 AM

Silvaire

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quote:

ORIGINAL: SoCal GliderGuider

Notice that the name on the above Thermic 36 is John Zaic. Could be that this design was reintroduced as a kit later thus you see the build up wings and fuse. Same with seeing the truss structed fuse for the Thermic 100 rather than the balsa block and tail boom of the earlier design.

The only similarities I see between the John Zaic/Jasco Thermic 36 design and the later Jetco kit is the name, wingspan, and the wing dihedral arrangement. In my opinion, the Jetco Thermic 36 is much prettier, with its Wolf Hirth wing plan form (wider chord flairing out beyond the dihedral break, then tapering to a sharp wing tip) and the full fuselage. I will try to post a picture of a Jetco Thermic 36 later.

The Thermic 100 had several variations during the Jasco era, but I do not have much information at hand right now. There is some information on the early Thermic 100 in the 1944 Frank Zaic "Model Glider Design" book that he published. There is even a drawing of it on the cover.

Just to confuse things a bit more, there was a Jetco Imperial 100 - a complicated V tailed glo powered monstrosity for radio control designed by Don McGovern. There was also a kit by Ace Products (of Pasadena CA) in the early 60's named the Zeus that was actually a very slightly modified full fuselage Thermic 100. There are no designer credits on the plans...

Arlen

< Message edited by Silvaire -- 1/1/2005 7:47:19 PM >

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RE: Handlaunch a Thermic 36? - 1/1/2005 5:05:37 PM

SoCal GliderGuider

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Second and subsequent printings of the 1944 book had the Thermic 100 on the cover. The original first publication didn't.

Just interesting trivia.

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RE: Handlaunch a Thermic 36? - 1/1/2005 7:41:01 PM

Silvaire

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Glider Guider,
I am not sure what the glider on the cover of your original Model Glider Design book is. This same glider as a smaller picture is also shown on the covers of the reissue 1934 and 1935-36 Junior Aeronautics Year books. I do not know if it was pictured on the originals. Not that it has struts. I do not think it was a model in the Thermic series, and probably not a Zaic design. There is a photo of it on p.189 of Model Glider Deisgn, but with no caption.

Here are some pictures of a JETCO Thermic 36, a Thermic Traveler (electric version, kit can also be built as glider), and two versions of the Thermic 100 - a pod and boom and a later full fuselage model.

Enough trivia I suppose, these old deisgns were just beautiful though!

Arlen

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