Rudeboy

Hello,

What prop would you guys recommend for a Fan Jett 50? From the website I gather this engine has to turn in the 24000 rpm range, correct?
Would the engine manage to get there on an APC 8x8 sport prop... or perhaps an 8x7 (sound small IMO)?

I ask because I am putting together a pylon type speed plane. I originally intended to power it with an MVVS GRRT engine... but something a little more user friendly is always welcome...

If the Jett can manage the 8x8, the performance of the plane shouldn't be too far from the performance with the GRRT.

bob27s

My Feedback: (19)

Hi,

Thanks for writing.....

You would not want to run the fan engine (as built) with a prop. Timings are for high RPM and optimized for the load of a Turbax-I fan. Dub is also not really producing rear intake engines any longer, but he still has some parts.

(*** See the last paragraph for the most direct answer to your question)

If you can tell me more about the plane, I can recommend exactly the correct engine. Engine rpm, prop choice, the airplane it is installed in, and other factors have a lot to do with which engine will do the job best.

Is the 8x8 a prop choice based on ground clearance? Or just something you had considered for the GRRT on the basis of RPM?

The curent QM40 engine is designed to run with an APC 7.5x8.25 QM40 prop - turns about 24K on the ground, and over 27K in the air. However, the QM engine takes some skill to work with, and does not have a throttle.

The stock Q-500 (AMA 428) engine will turn an APC 8.75x9W well over 19,500 rpm. This has a throttle body air valve, but not a true carburator. It is available with a standard Red-Jett carb if desired, but it costs you 500-700 rpm on the top end.

For "sport speed" use, Jett sells the side exhaust SJ-50 and BSE-50 combined with a Q-500 muffler, which will give equal performance (19K plus on 8.75x9), while being very user friendly... and it will throttle and idle as well. This is sold often for use on sport flown Q-500 aircraft, use in convered old F1 and QM40 planes to sport use, Shrikes, Diamond Dusts, Whiplash, and other applications where the side exhaust engine is desired and the aircraft will let the engine unload in the air. Benifit of side the exhaust is the standard jett-stream muffler is a simple bolt-on piece... no pipe to deal with.

The FIRE (rear exhaust) 50, when combined with a full pipe, will outperform ALL of them. Jett sells that combination very frequently for Whiplash and similar speed applications. Most folks run 9x8 or 9x9 props on this set up.

*** For the true speed freak, and this is sorta what you are looking for, the BSE50 FIRE engine can be provided in a high RPM varient, which uses the ducted fan sleeve. It is basically a front intake ducted fan engine that idles really well and screams on the top end. It is designed to run over 20K rpm. It takes care in operation... needle is a bit more sensitive. When you go to the edge, the engine becomes a bit less user friendly, but with proper care, an airplane that can make use of the rpm and let the engine unload in the air, the selection of the correct prop, and a superior fuel system (you must use a bubble-free fuel tank) the engine is a true animal. To order this, specify the fan sleeve, and tell Dub exactly which prop you wish to run. He will provide the engine, pipe and everything... completely tuned, test run, and ready to install.

I trust this addresses you question. If you provide me with more info on the application, I can help further.

Bob Brassell
[email protected]

Rudeboy

Hello Bob,

Thanks, that just about answers all the questions that were going through my head.

Below is a picture of the plane. This is not mine though, it is from a guy in the United Arab Emirates I believe. As you can see he also uses a Jett .50 FIRE.
The plane is basically designed around the use of FAI F3D pylon engines, but without the hassles of cowls and cooling problems... sort of like an every day training aircraft.
So the plane really doesn't need a 9" prop to make some speed.
I originally intended to use an MVVS GRRT pylon engine, and I even considered converting an MVVS .43 Marine GRRT (slightly more power) for airplane use. But that still leaves me with a not very user friendly plane for every day use. This thing has no wheels, so I have to hand launch it... that is not very convenient with a pylon engine screaming at full bore and only one hand to spare.

That is why I was considering a DF engine.

I think the Jett FIRE 50 with a DF sleeve would be just the ticket. That would make the install so much easier. The rear carb would be a bit of a pain to install in that narrow fuse. So the front carb is excellent, I just didn't know it was available.

Tell me what you think.

bob27s

My Feedback: (19)

Nice Plane...... I bet its pretty quick

Yep, the Whiplash setup (fuse-top header) and the high timed DF sleeve will work perfectly for what you wish.

If you wish to order one, drop Dub and email directly at [email protected] and tell him I recommended the DF FIRE configuration. He will get back to you on pricing of the whole package

Bob