Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

Spot Jett .50 in Sig Kobra!!

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Old 11-13-2007, 04:01 PM
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Default Spot Jett .50 in Sig Kobra!!

I've seen Kobras fly with .40's/46's; would sj .50 be too much for this little airplane? What mods might be required. How would one prop a little beast like this? Would the fuel tank be too small to have a resonable flight? Anyone tried it? Responses appreciated.

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Old 11-14-2007, 08:33 AM
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Default RE: Spot Jett .50 in Sig Kobra!!


ORIGINAL: J.T. Hammer

I've seen Kobras fly with .40's/46's; would sj .50 be too much for this little airplane? What mods might be required. How would one prop a little beast like this? Would the fuel tank be too small to have a resonable flight? Anyone tried it? Responses appreciated.

Hammer
No, it's fine, and it has probably been done - take a look at the similar projects on the Jett site. Someone stuffed a Jett .90 in a .40 size Patriot - that's a bit more radical than putting a .50 in a Kobra, so I wouldn't stress about it.

The SJ .50 is the same mounting dimensions as an OS .46 so mounting shouldn't present much challenge. 9-7, 9-8 for starters. An 8 ounce tank will give you reasonable flight time if you don't spend every second WFO, if you can fit 10 ounce then great. Jett bladder tanks highly recommended.

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Old 11-14-2007, 09:32 AM
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Default RE: Spot Jett .50 in Sig Kobra!!

Will be fine
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Old 11-14-2007, 10:25 AM
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Default RE: Spot Jett .50 in Sig Kobra!!


ORIGINAL: MJD


ORIGINAL: J.T. Hammer

I've seen Kobras fly with .40's/46's; would sj .50 be too much for this little airplane? What mods might be required. How would one prop a little beast like this? Would the fuel tank be too small to have a resonable flight? Anyone tried it? Responses appreciated.

Hammer
No, it's fine, and it has probably been done - take a look at the similar projects on the Jett site. Someone stuffed a Jett .90 in a .40 size Patriot - that's a bit more radical than putting a .50 in a Kobra, so I wouldn't stress about it.

The SJ .50 is the same mounting dimensions as an OS .46 so mounting shouldn't present much challenge. 9-7, 9-8 for starters. An 8 ounce tank will give you reasonable flight time if you don't spend every second WFO, if you can fit 10 ounce then great. Jett bladder tanks highly recommended.

MJD

yeah, what he said Stuffing a .40 into the little Kobra has been done many times before. (although I was always quite happy having a .46 or .50 in the normally .40 size Kougar).

Also, the bubble-jett tank will allow you to use 100% of the fuel. And you do not have to worry as much about padding the tank... kinda can cram it in there as long as it does not get dammaged. At WFO figure on a 6oz tank lasting 4 minutes. For sport use, you use the throttle for start up, landing, in flight... that is good for another minute or so.
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Old 11-14-2007, 03:35 PM
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Default RE: Spot Jett .50 in Sig Kobra!!

Thx guys. So I guess the downside would be the short flight time with the sj 50 in the kobra. I have built the kougar and used a mild k&b .60. Wasn't too fast but flew well. Building doesn't appeal to me as much as an ARF right now, but the Kougar as I remember was quite an easy build, and you can finish it the way you want. If I went that way I hope the Jet would fly it reasonably quick - does anyone have an idea of what the speed might be. I'm guessing maybe 120 - 130 mph. If slower than that, I'd consider something else. I believe you could put a 10 oz tank in the Kougar.
Decisions!

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Old 11-14-2007, 03:47 PM
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Default RE: Spot Jett .50 in Sig Kobra!!

Kougar or Kobra ---- thick wing - fixed gear ---- not going to go 130 very easily. But folks manage to get Patriot up that high with jett50 or 60lx power, so with some persistance it might happen.

As a reference, a Q-500, such as the Viper ARF, set up for 424 racing, TT40 pro (stock) tops out about 120mph in extended level flight.
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Old 11-15-2007, 08:47 AM
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Default RE: Spot Jett .50 in Sig Kobra!!


ORIGINAL: J.T. Hammer

Thx guys. So I guess the downside would be the short flight time with the sj 50 in the kobra. I have built the kougar and used a mild k&b .60. Wasn't too fast but flew well. Building doesn't appeal to me as much as an ARF right now, but the Kougar as I remember was quite an easy build, and you can finish it the way you want. If I went that way I hope the Jet would fly it reasonably quick - does anyone have an idea of what the speed might be. I'm guessing maybe 120 - 130 mph. If slower than that, I'd consider something else. I believe you could put a 10 oz tank in the Kougar.
Decisions!

Hammer
No matter how you achieve the horsepower necessary to achieve your speed goals, horsepower comes at the expense of fuel draw. Fuel mass per second = horsepower, efficiency notwithstanding. So you could say more generally that with oversized engines and limited tank volume, shorter flights (flat out that is) are to be expected no matter whose brand you choose. Most here tend to consider excess horsepower an advantage at all times.. flight time can be modulated with the throttle. Besides, 4-5 minutes at gonzo speed seems longer anyways. Fast and brief, quick but longer, moderate speed and longer yet, they all work for me on different occasions!

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Old 11-15-2007, 11:32 AM
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Default RE: Spot Jett .50 in Sig Kobra!!

You're right, I always set my timer for 5 minutes as my non Jett powered aircraft fly relatively quick, and 5 is enough! Would you or anyone have an idea how fast ( mph) a Juno F-20 would go with a Jett .60 LX? Or a Kougar with the same; both with fixed gear.

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Old 11-15-2007, 04:34 PM
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Default RE: Spot Jett .50 in Sig Kobra!!

Let me know how it goes, I always wanted one of these planes. I thought a Jett .35 would be about perfect.
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