nitro junky

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I just got a Thunder Tiger Rare Bear ARF .61-.91,63 tonight. Do any of you guys have one? If so how do you like it and what engine are you running?

proptop

My Feedback: (8)

Hey C. how you been?
Walt had one...he put a pumped O.S. 1.20 4 stroke in it...
It flew great...for a short period of time, then it dropped a valve.
He put a Magnum 1.20 4S in it, but the Magnum was doggy by comparison.

easton24

My Feedback: (1)

I knew a guy that used to fly at my club that had a os 160 in it. It was pretty fast to say the least. He flew it for a while till he had tail flutter.

rmenke

My Feedback: (13)

NJ:

Good to see you spend a little of those spare bucks you have been hording. Have had the Tony, Shoestring Rare Bear and Alley Cat all with Jett 90 power. Is a great sport flyer that is on the fast side, but not what most of us would call quick. The airframes are close to scale and fat and draggy, wings designed for sport flying, not speed. There is only one way to make them scoot, "gobs of power" and rpms! The 4strokes will give you the power but limits the rpm to around 12,000, and is hard on the engines. Dont think you will see much over 10,000 with the OS 160. The unlinmited warbird racers (60 sized birds) are playing with the OS 90 VRDF and the Byron fan motors, the Byron being the stronger and yes, they are scooting along very well, thank you, considering those motors like to run around 24,000. I picked up a OS 90vrdf for the AlleyCat, but it awaits mounting. The rear carb and exhaust are going to be a challange i'm not up to just yet. Along with the mounting, surface flutter at the higher speeds may or may not be a problem. None noted in a dive so far, but speeds even in a dive are not going to equal what the fan motors are going to give (I think). I liked the Rare Bear as well as any of the rest. That huge frontal area did not seem to slow the airframe down below the others a little more streemlined. Would hover with the Jett 90 and 11 X 8 apc which is interesting, but so does the Alley Cat. No, not torque rolls, loose it at the back side. Am not sure what it would do with one of the larger Webras, 120 or so. Do have a low time 120 in the engine cabinet, but never got around to sticking it in any of the subject airframes. Yell if you get hungry for a good engine, reasonable. ENJOY Bro 119

proptop

My Feedback: (8)

There was (is ) a huge thread in the ARF forum...I think it was the ARF forum?
(don't recall right off hand...don't think it was in Warbirds...)

nitro junky

My Feedback: (3)

The last owner of the plane told me he was flying it with a os 108. I took around 17oz of lead off the nose of this plane last night. So I was kind of thinking of an os 160. That would give me the wt. I need with out the lead.

Easystern

here is the fred dude, takes lots of time time to read all that, but it helps a lot to get it solid for high speed.
mine is almost ready with a saito180.
http://www.rcuniverse.com/forum/m_16...etracts/tm.htm

nitro junky

My Feedback: (3)

Easystern thanks for the link lost of grat info It looks like it will be an os 160

tom3097

My Feedback: (2)

Save yourself a lot of headaches and do a search on the Rare Bear here on RCU.They are well known for elevator flutter.Two guys in my club "HAD" Rare Bears.One of them didn't see that there would be any problem.First flight it fluttered,crashed and was a total loss.The second guy did the modifications he read about and it still fluttered and crashed.

nexusdc5

My Feedback: (4)

Hey Guys... Just started building a Rare bear myself and looking to make it much faster than most and flutter free. I Am Installing a BVM 91 SPEED DF Motor. This is what they are using in Some of BVM Jets and hauling Ass! Of course it means beefing up the front end and perforning a few mods to ensure the plane will hold together. Regarding the wing, you know how they want you too drive a small screw into the bottom of the wing into the Carbon tub... Well thats crap! Theres a much better way and it also eliminates the small gap when pushing the wing to the saddle. In the wing itself, Dont use the small alighning dowels, throw them away. Get your self some Bline nuts and install them from the inside of the wing ( you can reach them with out cuttung into the wing) Facing out towards to Fuse, install the wing onto the Carbon tube and install two steel 4/40 bolts into the Blind nuts pulling the wings into the fuse. This is a much stronger install and you can still remove your wings for transport. Now the tail flutter, Notice how wide the elevater is... Well just shave about 1/4 to 1/2 off the elevater ( at these speeds you will still have plenty of sensitivity in the elevater, But will also mean slightly faster landings. If your a skilled pilot, this shouldnt be a problem. After installing the elevaters, Then install clear plastic vynal tape, about 1 1/2 wide to cover the hing Gap top and bottom. With these two Combinations you will be able to go as fast as you want with out worrying about any flutter at all. It was a challeng Mounting my BVM 91 SPEED but will be totally worth the install. I hope these little tips will help some of you guys. Have Fun and happy Flying!!!

airraptor

My Feedback: (66)

how big is the cowl and how big a prop going to run.i dont see this plane being that fast with pylon engine 10" prop 9" cowl...........

OS160 or moki/mark 2.1

smoknrv4

My Feedback: (11)

Seems like a pretty draggy airframe for that engine, IMHO, Yikes.

C_Roundy

I obviously agree.... I will be motored with a DZ 1.70, to prop with about a 15" x 16" Narrow carbon, turning about 10,500 rpm static, on our scratch built molded rendition of Rare Bear that is about the same size as the T.T. R.B. arf.

A torque monster turning LOTS of diameter and GOBS of pitch is the solution to optimizing speed for a fat tear drop shape like Bear.
Very few people seem to understand the dynamics of this shape. Of course it has a massive amount of frontal area, so the engineering trick becomes how to put that to work for you and mitigate the disadvantage.

The right size and shape spinner does three huge things for you.
1) optimum tear drop shape as mentioned.
2) covers a large portion of the grossly inefficient inboard span stations of the prop saving ALL that horsepower for turning extreme pitch at the very efficient tip.
3) Drasticly optimizes the pressure zone into the leading edge of the prop, which increases efficiency markedly,
yet again.
These technique's and good ducting to reduce cooling drag result in a deceptively slippery airplane.

It is not by accident that R.B. holds the world speed record outright for piston engined propeller driven aircraft for 21 yrs running...

combatpigg

My Feedback: (3)

Rare Bear obviously works as full scale. Probably works OK as a very large model, but as you begin to scale that shape down, you can not scale down the air molecules it has to go up against.
This is why I put my money on skinny models with skinny wings, dollar per dollar.
I see a lot of guys seeking speed in this size range getting mediocre results for a ton of money spent.

C_Roundy

Absolutely true on just about all points C_Pigg, but as for myself, much of the challenge and the fun of our sport is in understanding and optimizing the airflow around ALL kinds of shapes to maximize speed, even fat scale shapes on occasion...

Thats the spirit that I chimed in with. You probably have some idea how many, many people love the experience of flying a gorgeous scale airplane to it's full potential. I respect their tastes well enough to help them achieve higher performance when I can; so much so, that on occasion I enjoy a scale project myself.

combatpigg

My Feedback: (3)

CR, I see your point. My comment is directed in general to a lot of larger models I've seen. The actual posted speed might even sound impressive, but the plane itself and the low pitched exhaust note [to at least my ear] aren't very impressive. When I factor in the cost, it has convinced me that the cost of making bigger stuff go fast follows along with the power / drag equations.
The exception might be the .90DF engine class. You can use "normal" HD gear and put together a combo that goes fast, sounds fast and isn't too overly stressed or expensive.

C_Roundy

Yeah, to double (size, weight, drag) and still go fast ya gotta cube money, something along that line ($ x $ x $)...

I too will always be addicted to the visceral experience of the sound of an extreme rpm piped 2-stroke; (I have owned, run, and flown at least 40 Jetts and nelsons across the yrs)

BUT, have you ever stood right at the fence, up and down a drag strip and listened (felt) a Harley Top Fuel drag bike run the 1/4 mile?
I gotta tell ya, the sound of a big bore, supercharged YS with a straight pipe, running 60% plus nitro definately leaves a deep and abiding mark on my soul too.

I do have trouble affording that much money per toy, so I don't usually (I probably have close to 3 grand sunk into my Bear for instance) but once in a while I must feel that kind of fire breathing beast too.

Put it in perspective though, look at the IMAAC guys, the hardcore pattern guys, the championship level heli guys, etc. none of them ever finish an airframe for any less than my most expensive ones.

Cheers!

C_Roundy

Here is a little Bear engine break in / tuning / telemetry flight video just to prove your point that the Reynolds numbers do let us go faster as we scale an airplane up. (unfortunately making our job harder with our little airplanes that flit more than fly[sm=47_47.gif])

http://www.youtube.com/watch?v=k0AZO...eature=related

290cc twin on alcohol/nitro/glow with straight pipes, running somewhere between 34 to 40 inches of pitch, probably close to a 50 lb airplane.

I'm curious, can someone extract his launch and unloaded rpms with software?

combatpigg

My Feedback: (3)

It sure sounds angry when he jumps on it!
I had a Fiat 600 cc car once....had I known giant model planes were going to be popular someday.....

C_Roundy

HEY!! If I want any crap outta you, I''ll just squeeze your head!!

for pity sakes, let that garbage go.

Just try....

C_Roundy

HEY!! If I want any crap outta you, I''ll just squeeze your head!!

for pity sakes, let that garbage go.

Just try....

marretta87

hay guys i had my first flight 2 weeks ago and it lasted seconds way to tale hev.

i balanced it like it says in the man but apon take off i was hovering lol littorally!!
well i poped my dacks and went back to idle but to late, only damaged 1 wing and is being repaird as we speak.
and for those wanting to no i have a turngy 26cc in her just for fun

where is the best balancing point for this modle??? plz help and when up and going agane ill try to get some vid for you all

ta