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Author Topic: Bear Sidewinder  (Read 3919 times)

Offline George Truett

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Bear Sidewinder
« on: March 17, 2017, 04:49:00 PM »
I'm wondering if anyone is familiar with this 80s slow combat design from Bear Model Products in IL.  I picked up an old kit at Perry, just couldn't resist.  Plans say originally drawn in 82 and updated in 83.  It's a complete, kind of interesting kit, center fuse is 1/2" hardwood, maybe pine and everything else balsa, I expect it will build pretty quickly.  I'm thinking of putting an OS 25sx on it just for fun.  There's not much distance between the leading edge and the engine, looks like a 3 1/2 ounce chicken hopper tank will just fit.  Anyone have any experience and/or suggestions?

Thanks,  George

Offline Dave Edwards

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Re: Bear Sidewinder
« Reply #1 on: March 18, 2017, 08:21:17 AM »
I think we are advancing from the disco era to the grunge rock era of combat!

Offline Ken Burdick

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Re: Bear Sidewinder
« Reply #2 on: March 18, 2017, 11:16:01 AM »
sounds like a good combination you have there. The os will be less vibration than what it was designed for and with the long nose that's a good thing.
It should be a fast and fun ride.

K

Offline Rich Perry

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Re: Bear Sidewinder
« Reply #3 on: March 20, 2017, 09:22:27 AM »
The Slow combat designs fly great with the long nose/tail moments.  The rules state a 5" distance must exist between the thrust washer and the leading edge of wing.  Then a minimum overall length of 26" If I remember right.  With a Fox .36 you needed a 28" overall length to get the balance right.  There are hopper tanks designed just for these planes, but if it were me, I would just run a bladder since yours does not have to be legal.  The point of the whole thing was they were meant to be profile aircraft.  They evolved far away from that. They also were not "Slow", especially with the advent of the Nelson.

Offline Terrence Durrill

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Re: Bear Sidewinder
« Reply #4 on: March 20, 2017, 03:13:34 PM »
I'm wondering if anyone is familiar with this 80s slow combat design from Bear Model Products in IL.  I picked up an old kit at Perry, just couldn't resist.  Plans say originally drawn in 82 and updated in 83.  It's a complete, kind of interesting kit, center fuse is 1/2" hardwood, maybe pine and everything else balsa, I expect it will build pretty quickly.  I'm thinking of putting an OS 25sx on it just for fun.  There's not much distance between the leading edge and the engine, looks like a 3 1/2 ounce chicken hopper tank will just fit.  Anyone have any experience and/or suggestions?

Thanks,  George


                I have two Bear Sidewinders and I powered them with Fox MKiV 36 Combat Specials.  I thought that they came out heavy and certainly need at least a 35/36 Combat Special of some kind for balancing as well as to have adequate power just to fly reasonably well.   D>K    H^^

Offline Rich Perry

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Re: Bear Sidewinder
« Reply #5 on: March 20, 2017, 08:11:17 PM »
Also, it was common to cut away some of the leading edge to fith the tank.  About an inch or so if I remember right.

Offline Matt Brown

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Re: Bear Sidewinder
« Reply #6 on: July 03, 2017, 02:14:23 PM »
I flew the sidewinders for several years in slow. They were a bit heavier than some others in that time frame. I always thought they needed more wing area. I stretched a couple to 42" span less tips but never flew them in competition. I switched to foamies about that same time. They took a really good combat special to fly well. If you missed the needle setting they flew rather poorly. I had (still have) one MKIII that was my favorite by far. My other MKIVs were just adequate.
If you are flying it with a 25, I'd cut down the elevator by about 25%. It was just too big and stalled the wing too easy.

Matt

Offline George Truett

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Re: Bear Sidewinder
« Reply #7 on: July 03, 2017, 06:09:55 PM »
Thanks Matt, since I first posted this I have come across a TT .36 and an ASP .32 so I may opt for one of them.  Several Mk IVs have been available, I haven't bought one since I don't see spending the money for an engine I will fly relatively little.  The OS La 40 has been suggested as a low dollar alternative to a Combat Special.  I doubt it will have the horsepower but it's supposed to be easy to run.  I still have a couple of stunters to finish up before I build the Sidewinder so I have a little time to make up my mind.

George

Offline Dennis Leonhardi

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Re: Bear Sidewinder
« Reply #8 on: July 07, 2017, 11:48:48 PM »
The Slow combat designs fly great with the long nose/tail moments.  The rules state a 5" distance must exist between the thrust washer and the leading edge of wing.  Then a minimum overall length of 26" If I remember right.  With a Fox .36 you needed a 28" overall length to get the balance right.  There are hopper tanks designed just for these planes, but if it were me, I would just run a bladder since yours does not have to be legal.  The point of the whole thing was they were meant to be profile aircraft.  They evolved far away from that. They also were not "Slow", especially with the advent of the Nelson.

For what it's worth, the Fox Mk IV on a slow combat model runs beautifully on balloon tanks - perfectly legal back in the day.  Fun times!

Dennis
Think for yourself !  XXX might win the Nats, be an expert on designing, building, finishing, flying, tuning engines - but you might not wanna take tax advice from him.  Or consider his views on the climate to be fact ...

Offline john e. holliday

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Re: Bear Sidewinder
« Reply #9 on: July 08, 2017, 11:48:45 AM »
Why do you need a combat special engine if you are just going to fly for fun.  I have an OS 35 on suction on my Jerkline Special and it is almost too fast for this old man.   Getting K&B 35 Stallions broke in for the Equalizer and a Fox 40 on the Guilitine.   To me it is almost like flying  a Bi-Slob with out the hovering a Slob does.
John E. "DOC" Holliday
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AMA 23530  Have fun as I have and I am still breaking a record.

Offline Matt Brown

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Re: Bear Sidewinder
« Reply #10 on: July 19, 2017, 08:38:30 AM »
Forgot about this thread. For the record, you really need a fairly decent engine on one of these. They are a little heavy with a lot of tail authority. Flying one on a stunt type engine makes it rather slow. It takes fairly decent speed so that it doesn't wallow through the air. 75 mph would be about the lower limit to really enjoy it. I think you'd be rather disappointed if you went with the LA40.

I think I still have a partial box of wing kits around. I know I robbed sheeting and spars from it though.

Matt

Offline George Truett

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Re: Bear Sidewinder
« Reply #11 on: July 23, 2017, 01:34:35 PM »
Matt, do you or Terrence recall what kind of RPM a good Fox MK IV or VI will turn on suction?  I just tried a Thunder Tiger .36 and got about 14.5k on a Rev-up 8.5x7 with my standard 15% R/C fuel.  Wondering how that compares with a .36 from the slow days.  Thanks,  George

Offline Terrence Durrill

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Re: Bear Sidewinder
« Reply #12 on: July 24, 2017, 01:36:49 PM »
Matt, do you or Terrence recall what kind of RPM a good Fox MK IV or VI will turn on suction?  I just tried a Thunder Tiger .36 and got about 14.5k on a Rev-up 8.5x7 with my standard 15% R/C fuel.  Wondering how that compares with a .36 from the slow days.  Thanks,  George
[/quote)


              I don't know the answer to your question.  I just cranked them up and flew them.  I am a sport flier at heart !      D>K      H^^



Offline Eric Parker

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Re: Bear Sidewinder
« Reply #13 on: October 17, 2017, 08:30:35 AM »
We flew and built a lot of Bear's Sidewinder kits. The fuselage is a pine fuselage. I agree with the other posts, if built stock it is a bit heavy and requires a healthy engine. The fuselage needs to be trimmed down or sanded a bunch. We also extended the wing about eight inches by cutting the finished airfoil out of foam and simply gluing to the wing. We didn't bother with the stock wingtips. The big key was, build it light. Some folks substituted the pine fuselage with a balsa fuselage. Good luck.

Offline phil c

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Re: Bear Sidewinder
« Reply #14 on: October 17, 2017, 09:34:00 AM »
Matt, do you or Terrence recall what kind of RPM a good Fox MK IV or VI will turn on suction?  I just tried a Thunder Tiger .36 and got about 14.5k on a Rev-up 8.5x7 with my standard 15% R/C fuel.  Wondering how that compares with a .36 from the slow days.  Thanks,  George

That combo should get you well over 80mph on suction, although these days most people would use a little less pitch to keep up the speed during maneuvers.  The TT36 will run well over 90mph on pressure and a large venturi.  But the shaft needs modifications or it will break rather quickly.  It's only 12mm, like the Super Tigre G.21-35.  Too small to hold up when it was running fast.
phil Cartier


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