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Jett .50 Super Sport and 9X8 APC prop, how much rpm?

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Jett .50 Super Sport and 9X8 APC prop, how much rpm?

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Old 06-22-2003, 10:54 PM
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JimmyA
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

How much rpm will I get out of a Jett .50 turning an APC 9x8. I want to buy an engine that can get me 20,000 RPM on a APC 9x8 I am 8ft above sea level so I am thinking the Jett .50 might do it. What do you guys think?

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Old 06-23-2003, 01:29 AM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

you may have to go to 8x8 to get 20000

I get 18500 with 8.875x8nn pylon prop on a Jet fire .50
I still have to cut .25" off the pipe
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Old 06-23-2003, 12:06 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

8000ft in Florida?
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Old 06-23-2003, 12:17 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Originally posted by Cyclic Hardover
8000ft in Florida?
Well, give or take 7992 ft

Originally posted by JimmyA I am 8ft above sea level
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Old 06-23-2003, 02:32 PM
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Default Re: Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Originally posted by JimmyA
How much rpm will I get out of a Jett .50 turning an APC 9x8. I want to buy an engine that can get me 20,000 RPM on a APC 9x8 I am 8ft above sea level so I am thinking the Jett .50 might do it. What do you guys think?

Jimmy

Jimmy,

The Jett .50 will do it with some minor changes to the timing and tuning. The current timing will not turn up there in the rpm department, but what you can do is call Dub up and tell him that you want a custom Jett .50 with higher timing, and tuning it for maximum rpm's with the 9x8 prop (I don't recommend 9x8 for high rpm, but instead use a 8.8x9). This will sure get you where you wanted, but you may have to sacrafice a lost of warranty for a customize high performance motor. Unless otherwise, stated differently by Dub himself.

My current Quickie Jett .40's will turn a 8.75x9W at 19,500 with no problem at all. So for the .50, it's no big deal. Just need a little tweaking that's all.

Hope this help!
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Old 06-23-2003, 04:44 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Originally posted by Cyclic Hardover
8000ft in Florida?
who said 8000 ft above sea level???? I said 8 ft. That is the exact elev. of the field. I am not sure where did you see 8000 ft in my post??

Jimmy
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Old 06-23-2003, 04:45 PM
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Default Re: Re: Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Originally posted by SSAN
Jimmy,

The Jett .50 will do it with some minor changes to the timing and tuning. The current timing will not turn up there in the rpm department, but what you can do is call Dub up and tell him that you want a custom Jett .50 with higher timing, and tuning it for maximum rpm's with the 9x8 prop (I don't recommend 9x8 for high rpm, but instead use a 8.8x9). This will sure get you where you wanted, but you may have to sacrafice a lost of warranty for a customize high performance motor. Unless otherwise, stated differently by Dub himself.

My current Quickie Jett .40's will turn a 8.75x9W at 19,500 with no problem at all. So for the .50, it's no big deal. Just need a little tweaking that's all.

Hope this help!
Thanks for the help

Jimmy
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Old 06-23-2003, 04:54 PM
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Default Jett .50

Depending on what plane you are putting the engine on, you may want to go with a larger diameter.

I'm running a Jett .50 on my Kyosho Spitfire. I've tried many props, and found that its fastest running an APC 10x7 at about 16,300 rpm.

I had a 8 3/4" x 9w (basically a 9x9) on there at about 1,500 more rpm, but it didn't pull the plane any faster. Just made a lot of noise. It also lost a lot of speed in the turns.
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Old 06-23-2003, 04:59 PM
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Default Re: Jett .50

Originally posted by daven
Depending on what plane you are putting the engine on, you may want to go with a larger diameter.

I'm running a Jett .50 on my Kyosho Spitfire. I've tried many props, and found that its fastest running an APC 10x7 at about 16,300 rpm.

I had a 8 3/4" x 9w (basically a 9x9) on there at about 1,500 more rpm, but it didn't pull the plane any faster. Just made a lot of noise. It also lost a lot of speed in the turns.
The engine will be installed in a Patriot kit. My old Patriot had .46FX w/tuned pipe and a 9x 8 was best for it. I don't want to get another 46FX for the Patriot after I saw one fly with a Jett 50. Anyway I will be experimenting with props and testing them with my radar gun. I am hoping to get the Patriot to 140MPH

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Old 06-23-2003, 09:28 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Jimmy,

Dave is right about the prop. The smaller prop's I mentioned/recommended is for lighter airplanes. I guess I didn't pay attention to what plane you have and recommended with the assumption of you having a lighter plane like a Quickie 500 etc. Please excuse...

The right props for the Patriot is an APC 9.5x8N or 9.5x8.5N (part numbers LP09580, LP09585). These props are best for this plane with the Jett .50 and will give overall speed and thrust as needed. Just call Dub Jett and have him specialize one for you for your specification. Although, please note that a Jett .50 will not pull 20,000 rpm with these props recommended, but will get you close enough. The thrust and speed will satify your needs for a little thumb shaking speed....

Again, these recommendation is based on the Jett FIRE .50 with a straight tuned pipe.

Hope this help!
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Old 06-25-2003, 06:33 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

The SJ-50 will turn the 9x8 around 18,000 with the SS muffler, after proper break-in.

As noted in the previous post, prop selection is important. Do not worry as much about ground RPM... prop the engine for where it wants to run and for good flight performance, and let it unload in the air.

The Patriot is a 'big' airplane...lots of frontal area.... it needs some pull up front.

I fly my SJ-50 powered Patriot with a 8.75 x 9W. Cost me a few feet in take-off roll, but I like the way it unloads in the air. Good level flight speed (never measured, but it is quick). The prop has a wider/thicker tip than some of the other pylon props, and works fairly well in this application. Plus, I have a bunch of them laying around The SJ-50 turns this around 18,500 at launch.

I had suggested the 9W to daven (above) as an experiement, and with the spitfire it didnt work all that well. Prop selection is important.

For comparison, my BSE-500 will turn this prop at 19,700 (peak) on the ground, and I can launch it at 19,300.

Q: the .50 is more powerful, why lower rpm ??

A: The major RPM difference is in the muffler.

If you do not mind using a thinner/flatter/smaller prop that will allow the engine to turn over 19K on the ground, and you can be a bit more precise on your mixture settings, and you are not as concerned about midrange and transition....simply install the Q-500 black muffler on the .50, and it will happily turn up for you.

Dub sells the .50 and Q-500 muffler quite often for guys just wanting to go fast sport flying Q-500 and QM aircraft.... a lot more user friendly than the Q-500 engine, more power, and runs great.

For the Patriot, your best bet is the SJ-50 with the regular muffler. Take the 18K rpm, and prop for best performance.


Bob Brassell

Jett Engineering support
webmaster@jettengineering.com
bob27s@hotmail.com
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Old 06-25-2003, 07:50 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Bob,

Thanks for all the info. I am going to take your advice and get the SJ 50 and try different props on it. BTW, How long of a flight should I expect out of an 8oz tank? I am going to try to fit a 10oz in there but not sure if I can.

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Old 06-26-2003, 11:33 AM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Fuel consumption........ hmmmmm...

Figure on burning 1.2 oz per minute at full throttle (18K rpm or so ), but never running the tank completely dry (you do not want the engine to suck air or foam at the end of the tank... instant lean condition, fried glow plug and eventually damaged engine).

In other words, figure on about 5 - 6 minutes for an 8 oz tank.

I am trying to locate a suitable 8 or 9 oz bottle which I can fit into the fuel tank area. I want to fabricate an 8oz bubble-jett tank to try in the Patriot. The 6 oz tank worked great last summer, but flight time was a little less than 5 min.
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Old 06-26-2003, 10:48 PM
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Default Jett .50 Super Sport and 9X8 APC prop, how much rpm?

Then It might be a good idea to try using the 10 oz. tank. On my older Patriot I was able to stuff a 10oz GP tank. I am going to do that on this one again. It was a very tight fit and I had to slightly sand the inside of the top Balsa cover. Thanks for your help.

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