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Old Sep 16, 2009, 11:12 AM
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Highfly!'s Avatar
United States, CA, Cameron Park
Joined May 2007
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I have been flying the Kunlun for quite a while now being actually quite aggressive flying it with high pulls from dives measuring at one point 82 miles with my logger with no signs of failure whatsoever.

Besides gluing the wings together I exchanged the rod using a CF rod which I managed to push another 17 inches on each side of the wing (see post 105). I also worked on removing as much as possible weight behind the CG by eliminating the rudder, moving the elevator servo forward and exchanging the iron rod to CF. I still needed some weight in the nose but it came out quite (relatively) light and flies decently.
Overall not too bad for a $90 plane which although has some design issues can be quite enjoyable to fly if assembled right.

I have also a GP Siren which flies much better and had fewer issues to deal with, can even thermal costing only $50 more. If you are looking for something between the Siren/Kunlun and the expensive hot liners out there I can recommend having a look at the Multiplex Blizzard as well which is in the same price range.

Good luck with your build!
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Old Sep 16, 2009, 11:55 AM
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United States, IA, Cedar Rapids
Joined Apr 2006
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82 miles of flying or 82 mph? Lets see some graphs!

Your earlier post refers to a hollow CF rod, which most vendors call a tube. It that just a cheap pulltruded tube or wrapped? Did you actually drill through the ribs to add the tube? If so, did you attach a drill to the CF tube, or use a metal tube with the end sharpened?

The advice I've gotten is that I should cut the blasa skin in between each rib on the bottom, just behind the spar, add some support to the webbing (balsa cut so the grain runs between the upper and lower spars), and then close it up with monocoat. Sounds like a winter project.
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Old Sep 16, 2009, 02:19 PM
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Straight dive from 700ft with motor running gave me 82mph. The pull-up went without leaving any wing behind as other users were noticing on their Kunlun.

The CF was hollow reinforced with a wood dowel inside. I did glue a drill to the CF tube and worked myself through the ribs. I have seen others adding webbings which seemed to me too much of an effort.

So far the wing has held very well although I must admit that unlike my Siren and Blizzard which I really work hard the Kunlun has been handled more gently after my initial stress tests.

Given the amount of effort I had to put into making it where it is today I would not buy it again.
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Old Sep 16, 2009, 09:31 PM
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United States, CA, Cameron Park
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Just had a look at the Nitroplanes website and saw this new glider http://www.nitroplanes.com/alps-rc-glider.html

Looks like a modified Kunlun only a bit smaller...
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Old Sep 17, 2009, 08:45 AM
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United States, GA, Flowery Branch
Joined May 2001
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Highfly: Thanks for the link. It looks like there's another manufacturer in southern China producing plastic and balsa motor gliders for us. The Alps reminds me more of the Omei (no rudder) than the Kunlun. The only problem with this low cost line of molded fuselage and balsa-winged sailplanes is you don't know what's under the wing skin until you crash one to find out. I wish these manufacturers would feature more pictures and details of how strong their wings are built rather than info about how nicely the "water transform decals under the glossy paint finish" look. But it may be worth a look as it may not have the tail-heavy issues that the Kunlun does.

I'm still not done with my Kunlun as I'm very involved with other things right now. But I did go to the flying-dream.com website to see what's there. There wasn't anything more about the Alps, but they did have a very nice looking 2.6 meter Discus with, of all things, an optional ducted fan power pod. Picture below.
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Last edited by Joel Shreenan; Sep 17, 2009 at 09:06 AM. Reason: Added image.
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Old Sep 17, 2009, 01:32 PM
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Is it just me, or is that the dumbest idea ever? To get any decent thrust out of something that small, the velocity is going to have to be over 100mph and I can't imagine the drag being anywhere near as low as a folded prop. On big sail planes, I've seen a pod that flips up in use and the drops into the fuse for low drag. I have to call style over substance on that design. Then again, a plane that looks as nice as the Kunlun but with webbing oriented wrong is style over substance, too.

I agree with you Joel. Maybe we should all agree to buy the first plane that comes out with cross section pictures of the wings and fuse so we could see what we're really getting. That would help reinforce the idea that consumers pay attention to these things. The sad part is the well made kits don't really advertise how good they are, so I'm an idiot and buy the cheapest and prettiest and wonder why it's a poor performer.

For what it's worth, the wings of the "Stratus 1700/Fantasy Angel" are made similarly, but a little better and they're smaller so they don't seem to have any issues. The wings on it are polyhedral and I managed to break one right on the seam where the two root-like surfaces were glued together.
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Old Sep 17, 2009, 03:08 PM
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Mark: you make some good points there. One of the reasons I love this website is all the good information that is so freely exchanged. Hopefully, someone will not buy a Kunlun with unrealistic expectations after reading through this thread.

I'm planning on using strips of hard balsa and basswood with carbon fiber strips and a CF square tube inserted into the wings through the openings in the wing ribs. The 1/4" square CF tube is extremely rigid, and in addition to adding strength to the wing, I'll use it to carry the aileron servo wires down through the wing. The CF items will be CA'd to the balsa/basswood strips and then the assembly will be slid through the rib holes. I need to stop procrastinating about this project and get my act together. I've got all the parts--all I need is the time. Joel
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Old Sep 17, 2009, 03:33 PM
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Joel;
I looked at the Alps again and remembered that I saw a review in a German magazine (modell aviator) I picked up last month in Munich on my way back. The same model is sold by Jamara and I found this link with a bit more meaningful description http://www.neuershop.jamara.com/inde...=3368&lang=eng.

The German reviewer calls the Alps a Thermikhotliner and did not mention any issues with the wings. The Alsp needed about 180 grams of lead to get the CG at 52mm which proved to be way too much. He stated that after reducing the weight by 100 grams a CG of 67mm proved to give a very stable and responsive flight. It thermals reasonably well and can even do some basic aerobatics. There was also a mentioning that the fuselage is made out of Terran which is a bit heavier than fiberglass but very durable and easier to repair.

I donít think that this model is from a new vendor but still a CMP design using a new brand. The Discuss looks interesting but the EDF pod seems very questionable to me. Must be producing an awful lot of drag and besides I donít like the noise EDFís are producing.

I suspect that the wing has the same issue as the Kunlun but I am comfortable with the wing modification I made on my Kunlun to do the same on the Alps if I get it. The suggested price in Germany is 154.90 Euro and at Nitro it is $89.95 which I think is a very reasonable price.
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Old Sep 17, 2009, 05:28 PM
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United States, GA, Flowery Branch
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Here's an interesting way to power a model sailplane. How about a gas turbine? Why not two turbines?

9 meter turbine powered sailplane go down (4 min 56 sec)
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Old Sep 22, 2009, 05:45 PM
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Highfly I like your method of extending the wing joining tube by using a 6mm CF tube then running rod inside that.

How did you drill through the ribs to get the 6mm tube in - you say you glued a 6mm drill to the end but how do you glue a 6mm drill to a 6mm tube so that its all nice and straight and isn't more than 6mm diameter where the glue is?
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Old Sep 22, 2009, 10:19 PM
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Mark,
The outer diameter was 6mm and the inner was if i remember 5mm. I used a new 13/64 drill and slowely worked myself through the ribs. As the ribs were soft balsa I managed to gently push the rod further down the wing.

Before I glued the rod into the wing I took a 5mm dowel and pushed it inside the tube for extra strength.

Works great or maybe I am just lucky.....

Good luck!
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Old Sep 23, 2009, 04:32 PM
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Thanks Highfly

I will do exactly the same with the tube but I am keeping separate wing halves so will use a 5mm solid CF rod as the wing joiner. Sounds a bit worrying that the ribs are so soft. I was thinking I might run a second 5mm tube up each wing half in the rear rib cut out and 4mm rod in that. Danger is you make it so rigid up to the servo boxes that it will break immediately beyond them. Still the load outboard of that isn't too great and if I make the second tube about 3in shorter than the first it will taper out the strength a bit.

I,ve already got the motor in. I'm running a 23281 | 4445720 JP EnErG Pro C35-26 870 RPM/V Brushless Outrunner Motor with a Graupner CAM 13x7 prop on a 4S 2200mAh pack. Peak current is 50A producing just under 750W. I,m almost afraid its too much!

I've got the battery and ESC on a new tray under the canopy and the RX and elevator and rudder servos where the original battery tray was. I've left the original servo trays in because although it is weight behind the CG it adds strength, I think. Obviously I've yet to finish the wing but it looks like I'm going to get everything to balance without adding lead which gives me a weight of about 1400g which I'm pretty happy with.

It looks too lovely just to float around and I know I won't be able to resist the temptation to fly it fast and throw in lots of aeros. I think if I keep it smooth and avoid "bank and yank" type manouvres it'll be OK.

Thanks for all the tips from you and everyone else.

Mark
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Old Sep 23, 2009, 05:18 PM
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Anybody know what that glue is they use for bonding the ply to the inside of the fuselage? Doesn't seem to set too hard -stays felxible and not brittle and seems really strong.

Mark
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Old Oct 09, 2009, 03:35 PM
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Norcross, GA
Joined Dec 2005
277 Posts
Kunlun

I started on my Kunlun today. I made a narrow slot the length of the spar on the bottom of the wing. I installed a 4mm wide piece of carbon fiber using 30 min. epoxy. I will post the results after the first flight. Thanks to everyone who for all the very helpful information on the Kunlun.

George
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Old Oct 09, 2009, 04:17 PM
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United States, CA, Novato
Joined Sep 2003
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Just an update. My buddy has been beating the tar our of his. I'm not sure of all of the upgrades he has done to the wing on his, but he has proven to me that it is pretty tough.

Lets see, he has busted the fuse many times. Actually flew into a tree inverted at speed and only dented the leading edge after falling 100 feet out of the tree! Beats it pretty hard in the air.

He may not be a great flyer, but he is usually entertaining to watch. :P

-Wayne
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