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Jul 08, 2016, 01:38 AM
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Have fun Greg do you have an altimeter at all? We have a little Hobbyking one (a gram or so) so I might start recording launch heights.

Jon
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Jul 08, 2016, 02:42 AM
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Quote:
Originally Posted by Bmwjoon
I bought a cheep digital one on amazon. Works great.
Just ordered one for about 3. Will be good for testing set ups.

I've started adding bungee links to post #3
Jul 08, 2016, 03:23 AM
supreme being of leisure
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Quote:
Originally Posted by glidermang
Tomorrow, we will be flying both a Pures and a Slite from a F3B-RES specified hi-start. I fully expect to see the whole thing stretched vertically. Tension is not the full story on launch height from a hi-start, by any means.

I will let you know how it goes.

Yours, Greg
very true! the sheathed shock cord i use is way too heavy to be pulled up vertically like that, more like a big sagging arc. have to use a lot more line to get a similar launch as bare rubber but increasing the line length also has its limits. bare rubber just gets chewed up too quickly for me.
Jul 08, 2016, 03:37 AM
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Zagnut, I've had a lot of success with long but thin shockcord - 30m of 3mm from ebay. It still only stretches about 2x but it's light enough not to sag. It has plenty of power to launch a 420g model in wind over about 5mph.
Jul 08, 2016, 03:59 AM
supreme being of leisure
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Quote:
Originally Posted by slowmatch
Zagnut, I've had a lot of success with long but thin shockcord - 30m of 3mm from ebay. It still only stretches about 2x but it's light enough not to sag. It has plenty of power to launch a 420g model in wind over about 5mph.
i have yet to fly anything super light like these new planes, my 2m planes are around 900g. my shock cord looks like ~6mm and the 25m length stretches out to a bit over 80m. only at full stretch does even lift off the ground...

nice to know that the standard 2X stretch bungee works fine, i've always thought it wouldn't work so never bothered trying it. it is much, much easier to find than the stuff i have.
Jul 08, 2016, 07:08 AM
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I've been following the various discussions on these planes with interest. As the cost of these competition planes is relatively low and they are easy for one person to launch and fly, I think they have a great potential to increase interest in flying 'gliders' as the power guys, call them.

Thanks for the thread.

EJ
Jul 08, 2016, 07:24 AM
LJH
LJH
Moths do not fly inverted
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Interesting to know that regular shockcord will work. Being a sailor I use LOTS of shockcord and they vary widely in stretch and longevity. I happen to work in the recreational sailboat industry and a company that we represent here in the US has just developed a Dyneema jacketed shockcord. I have been using some from the beginning of the sailing season and so far so good but I will know better as we get later into the season. This shock cord stretches almost 2X the original length and because of the Dyneema jacket it should be pretty bullet proof. We go down to 3MM (1/8") so once the RESoholic is built I will give it a go and see how it works out.

Cheers,
Jim
Jul 08, 2016, 08:34 AM
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Well, it seems I lied. The guy with the new supply of rubber tubing had to back out, so no trials of the new hi-start. Hopefully, next week.

What I've found about hi-starts: my best performance is about 20% elastic, 80% string. The string has to be light, but surveyor's twine works OK (and is brightly colored). The parachute can be traded for a simple, light-weight streamer, although a parachute that closes on the way up doesn't hurt at all. For light-weight airplanes, longer-but-thinner tubing does much better than thicker tubing - you can store a lot of energy on the stretch, without generating a lot of tension. For heavier airplanes, thicker tubing is necessary. Please note that all this is subjective.

When we get the real deal laid out, we will have a spring scale, and we can generate some objective numbers.

Yours, Greg
Jul 08, 2016, 09:35 AM
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Jon:
Is this thread only for kitted designs?

The RES-Dart flying wing is pretty neat. Might be good to post a link to it here, if you're interested.

-Dave

PS: for a RES flying wing, is it necessary to use tip rudders, or is it OK to have Aileron, Elevator, Spoiler?
Jul 08, 2016, 09:42 AM
Registered User
Actually in the rules there is a minimum diameter for the line. Don't quote me but I think it says .8 mm. Obviously the thinnest stretchiest line is the best.

What that basically equates to is 70-80 pound test mono. I'm using 80 pound (.9 m) and it's relatively light. The only downside is mono isn't terribly durable especially if you are flying in a rough area.

I tested the XRES to roughly double the recommended launch tension and it has no problems with the higher forces which probably only last 2-3 seconds. I'm still tweaking the hook position. I have it almost all the way back and it does launch better and better. A little bit of the trick compared to a winch is the launch angle which feels really vertical. I got the best effect when I just hurled it straight up as opposed to more horizontal.
Jul 08, 2016, 09:46 AM
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Oh here's a link to the mono I'm using

https://www.amazon.com/gp/product/B0...?ie=UTF8&psc=1
Jul 08, 2016, 12:10 PM
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I did some pull tests in 2004 on 3 different high starts I had at the time. The Hosemonster 2m rubber comes very close to the pull spec based on the Hosemonster info and my independent pull test back then. I still have those high starts, but age may have affected their properties in the 12 years since these tests were done.

https://www.rcgroups.com/forums/show...9&postcount=40


EJ
Jul 08, 2016, 02:16 PM
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Dave, no its for everything - including homebrews and own designs, I'm just adding links slowly as I go. If you want to pm me with links I'll add them.

The German language ones I've added are via google translate - if anyone has dud one can you let me know please?


Btw, minimum line diameter is 0.7mm, about 50lb I think.

Jim, what do you sail? I'm just about to launch my boat for the week

Jon
Jul 08, 2016, 03:06 PM
LJH
LJH
Moths do not fly inverted
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Quote:
Originally Posted by slowmatch


Btw, minimum line diameter is 0.7mm, about 50lb I think.

Jim, what do you sail? I'm just about to launch my boat for the week

Jon
Jon,
On the line that is good to hear. I have a spool of polyester whipping twine on my desk here that is .8MM and is coated. It comes on 90M spools and is dirt cheap....the only down side is that it is not all that stretchy but I will try it and see how it works out.

On the sailing front I am pretty lucky, I have been heavily involved in sailboat racing since my teens and still get some pretty decent rides. My ride currently is a turbo'ed Swan 45 which is just perfect in my eyes....she is fast, comfortable and sails to her numbers really well. Before the Swan 45 I sailed in the Club 42 fleet which was really good fun and very competitive with out being all "Pro'ed" up. Before the 42 I did the Swan 45 thing when there was a fleet here in the US. As I mentioned the boats are great but when they were sailing them one design the boats were filled with Pro's and it got a bit tedious dealing with them.....but it was super fun sailing them in Europe....the Swan folk throw a good party at some spectacular venues. Before that I sailed in the IMS40 fleet on the East Coast. When I was in my mid 20's I did some pro sailing in Europe and the UK on IOR boats and very early IMS boats.

My wife and I also have a few boats, we have an old Alsberg Express 34 that we cruise and race very casually, we also have a 19' sport boat called a K6 which is super fun but unfortunately never got a lot of traction here in the states so we are limited to sailing her in the fleet at our club. Then there is the Cook 11 which we frost bite, a Vanguard 15 that has been sitting in the driveway for 5 years (want to buy it?), and our son just started Opti 1 so we added one of those to the armada this spring.......

Ok....we might have a problem with boats.......

What are you sailing?

Cheers,
Jim
Jul 08, 2016, 03:39 PM
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Wow! Swan's are the bees knees

I sail a Hunter Europa 19 foot cruiser racer. Bit of a different league but she's my baby and she gets around had a 3 week, 300 mile cruise with her last summer on the UK east coast, 2 up for a week but mostly singlehanded and including some night passages. I don't race her but I'm always racing her

Jon


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