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#1 vigli Oct 09, 2012 02:55 PM

Talon airfoil
 
Hi
I have Talon kit. Do You know which airfoil it has. I have Dynaflite Talon.
Hmmm airfoil does not look thin...
Is this unusual for slope sailplanes?
thanks
best
boris

#2 soarntz Oct 09, 2012 03:02 PM

I imagine someone here will know the name and number. However, years ago, we flew Talons at our slope here in Central PA. We had a rough landing area then and were constantly repairing or replacing things. I made Replacement Wings by tracing each rib onto paper and cutting them out by hand. Not really all that much work as there were few ribs. The "Replacement" flew just fine.... Until I broke it and needed another. Thank goodness for EPP!

#3 TRISME Oct 09, 2012 03:09 PM

I think it was an Eppler 205.
Tom

#4 prodjx Oct 09, 2012 03:52 PM

I think it's a E-374 I also have drawing's of a modified Talon Airfoil From Jeff McDonald. It's a pretty good sloper still.

#5 steve wenban Oct 09, 2012 03:57 PM

E205
 
Yep that was pretty much the foil of choice back then still holds up pretty well today
I have the talon instruction manual here to if you need it

Edit could very well have been the 374 but have a feeling it was the 205

#6 Snewk Oct 09, 2012 05:39 PM

An article in the May '89 issue of Slope Soaring News regarding Talon modifications mentions that the airfoil is the E205. Here's a link to the entire published series.

http://www.rcsoaringdigest.com/SlopeSoaringNews/

Ken

#7 prodjx Oct 09, 2012 07:33 PM

Thank's Snewk.

#8 vigli Oct 10, 2012 01:27 AM

Thanks a lot

#9 Crash Prone Oct 10, 2012 10:30 AM

PM Kevin of ZAerotech (z-22, z-33 etc.)

I have a feeling he will know! ;)

#10 BigSwede Oct 10, 2012 10:41 AM

Here are couple of quotes from one of Bob's friends from another thread;

"All Bob Martin models had french-curve airfoils hand drawn by Bob himself. He did not utilize any other designers engineering data to develop his model lines. Everything is totally Bob Martin through and through. I know this for a fact as he told me so earlier this summer."



"The plane began as the LR-50, a design by Kevin McDonald that Bob says had many issues when Kevin brought it to him to market. Bob had to make many changes to the design including the airfoil, empanage, feathers so it would fly good. The assembly technigues were also adjusted for better modeling purposes. Then he bought the rights from KM and called it the Talon. This is when the model took off towards 2000 units a month! So the final design was completely revamped into Bobs Talon we know today."

#11 Snewk Oct 10, 2012 04:44 PM

Outstanding detective work, BigSwede! I recall reading that quote some time in the past but had totally forgotten it. I've still got a vintage Talon with a fully sheeted wing hanging in the garage but can't see crosscutting the wing to check out the foil. :o Back in the day the E205 was "cutting edge" and "high performance". Still not a bad foil for low lift slopes.

Ken

#12 MattyB Oct 10, 2012 06:50 PM

Quote:

Originally Posted by Crash Prone (Post 22962714)
PM Kevin of ZAerotech (z-22, z-33 etc.)

I have a feeling he will know! ;)

Quote:

Originally Posted by BigSwede (Post 22962801)
Here are couple of quotes from one of Bob's friends from another thread;

"All Bob Martin models had french-curve airfoils hand drawn by Bob himself. He did not utilize any other designers engineering data to develop his model lines. Everything is totally Bob Martin through and through. I know this for a fact as he told me so earlier this summer."

"The plane began as the LR-50, a design by Kevin McDonald that Bob says had many issues when Kevin brought it to him to market. Bob had to make many changes to the design including the airfoil, empanage, feathers so it would fly good. The assembly technigues were also adjusted for better modeling purposes. Then he bought the rights from KM and called it the Talon. This is when the model took off towards 2000 units a month! So the final design was completely revamped into Bobs Talon we know today."

Interesting, but Kevin has a very different viewpoint...
Quote:

Originally Posted by KJMDES (Post 4160659)
Sorry about the short post. I was off to France in the morning and bit tight for time. Relaxing in Italy now, starring at a slope to-die-for and wondering why I left the ship in Scotland.

I thought it was about time to post a little treatment on the Talons history and some inside skinny. And also, to give you the direct URL for the SuperTalon. Go here and then click on New Designs for 2004http://www.kjmdesign.com/kjm_m04_rc.htm. Which, by the way, was of little or no interest to Dynaflite. Not that it’s anything groundbreaking. Seems I had been laboring under the false assumption that there was some interest in an upgraded, high performance alternative. Unfortunately, the ARF scene has pretty much destroyed the kit market as we knew it. This wouldn’t bother me so much if it weren’t for the shear mass of total crap available. Don’t get me wrong, there are some nice ships out there, but they are expensive and are rarely domestic. Seems we are destined to hand this market overseas as well. If this doesn’t bother you, maybe it should. The implications are broader than just loosing another creative asset. It has forced the small domestic manufacturers (who once produced high quality kits) to jump ship and try to compete by consolidating with other junk suppliers. Stripping the supply of building material is just one consequence. Filling trash bins is another. OK, enough said.

Back in 1984, an old friend, Bruce Lewis, and myself, were heavily involved in designing and building RC sailplanes. Bruce was actually the catalyst for many of us getting involved in the sport back in the mid-seventies. Bruce is a master at most anything he tackles and I, well, I’ve got my points.

So, here we are in ’85, I’ve started a new company, Laminar Research, and we are finishing up a new design called the LR-50. A foam and glass V-tail ship that was designed from the get-go to fit in a trunk, assembled. We generally flew at Sunset beach and we packed a lot of big stuff in. Bruce had a competition 2M slope ship design, and so did I. Mine seemed a better starting point to scale down a new ship. So we put our heads together and came up with the new ship. Testing went well and after a year and a half, we developed what was one of the first successful V-tails around. Between a foil section unique to our designs and exhaustive testing of angles, sweep, etc., we ended up with a very solid performer. I have no idea how many LR-50’s we produced, but there were a few dozen to be sure.

Sometime around ’87, I was prompted to design a built-up version of the ship and in that same year I was on a hill in Cerritos, California, testing the proto when someone walked over and asked me some pointed questions about the design. It turned out to be Bob Martin, and we struck a deal to put it into production. I never quite knew if he was pulling a fast one, or genuinely believed that the Talon would not be much of a seller, but, in any event, my royalties were limited to two thousand units. I’m told sales are somewhere over a bucket-load of units at this point. The other thing that was a bit odd at the time was Bobs insistence that I design a conventional tail. We compromised by having two options

OK, lets move onto the nitty-gritty. When I received my first sample production kits, I immediately went ballistic. My original plans and sample kits delivered to Bob had specified spruce spars. He substituted balsa. There were also 1/64th ply doublers running full length, on the inside of the two large fuselage side strakes. The main foil section was also modified. I immediately ripped off a post to all the BBS sites and my own site at the South Bay Soaring Society, listing these changes and the fixes. The final insult came when he sold the kit rights to Dynaflite. The plans now credited him with the design. It took awhile, but now there is suppose to be a change to the plans, sticker, or something to correct that bit of plagiarism.

I will soon put together a list of mods that I have made to the original ship. The SuperTalon is basically the same ship with a 60 inch span, ballast tube and four servo wing. It’s a goer. Too bad Dynaflite is too wrapped up in ARF’s to be interested. Or, for that matter, upgrading the Die-crunch parts. Or even, selecting balsa that is remotely close in weight, side to side. I received two sample kits from them last year and literally thru away half the sheets in order to get one ships worth of semi-matching parts. It’s a sad state of affairs. However, I would suggest that if anything is going to happen regarding kit quality, be it the Talon, or any other kit, you need to email Kevin Burner at Great Planes and lobby for the change.

So there you have it. Good flying
Kevin J. McDonald

You decide, but having seen the stunning quality and high end design work Kevin has put into the Zaerotech products (my Zip 33 v2 is currently on the bench) I find it impossible to believe the LR50 was the flying dog Bob Martin claims.

#13 BigSwede Oct 10, 2012 07:21 PM

I didn't even realize it was the same Kevin as Zaerotech Kevin. I have no insight here, as I just remembered reading that thread that I quoted. We all know tht everything written on the Internet is true, right?

#14 MattyB Oct 10, 2012 07:36 PM

Quote:

Originally Posted by BigSwede (Post 22967097)
I didn't even realize it was the same Kevin as Zaerotech Kevin. I have no insight here, as I just remembered reading that thread that I quoted. We all know that everything written on the Internet is true, right?

Every word my friend, every word... ;) :D

Ps - There was a thread somewhere where Bob responded, let me see if I can dig it up. Ah yes, here it is... (see next post)

#15 MattyB Oct 10, 2012 07:42 PM

They don't call me Sherlock Matt for nothing - here you go!

http://www.rcgroups.com/forums/showt...1272508&page=7


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