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

Predator II and Jett 50 speed

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Old 08-25-2006, 09:41 AM
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Default Predator II and Jett 50 speed

Predator II and Jett 50, anyone have any experience with this combo? Flown it about 4 times, not overly impressed so far. Think it is probably doing about 130 or so on an 8x8, hoping for 180+. Am I expecting too much? Any recommendation for an engine and plane combo that will do 180-200? Also the Jett seems to vibrate a lot, prop is balanced and in plane, is this common?
Thanks
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Old 08-25-2006, 10:05 AM
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Default RE: Predator II and Jett 50 speed

ORIGINAL: ecoliburger

Predator II and Jett 50, anyone have any experience with this combo? Flown it about 4 times, not overly impressed so far. Think it is probably doing about 130 or so on an 8x8, hoping for 180+. Am I expecting too much? Any recommendation for an engine and plane combo that will do 180-200? Also the Jett seems to vibrate a lot, prop is balanced and in plane, is this common?
Thanks
NO way the Pred2 is going to get anywherwe near 180.

The top end competive QM40 planes just about get to 180 mph.

Competitive 428 Q-500 aircraft fly upwards of 160 mph.

Wrong prop. An 8x8 is way too small.

You want to use an APC D-1 8.8x8.5 or 8.75x9W. A stock APC 9x8 is an alternative.

The Jett 50 with the stock muffler with get either of those props up around or over 17,500 peak rpm on the ground. If you have the SS muffler, it will turn slightly higher. Launch the engine set 500-600 rpm down from peak.

The engine produces a great deal of power. It is not likely vibrating (make sure the prop is balanced, and that the prop-mounting-stud is NOT turned in all the way - must be a turn or two from bottomed out). More likely, it is the airframe not transfering the power well. The front end of a stock predator 2 is not stiff enough for more than 424 engine power (tt.40pro) unless you make sure there is triangle stock behind the firewall, and you glue the tank-hatch/cover securely in place.

Top speed to expect , properly set up, in level flight straight line - around 140-150 mph.

I hope this is helpful

As for 200 mph capable....

Properly configured Whiplash aircraft with Jett FIRE 50LX and 60LX engines have been documented over 200mph using radar measurements. A few other specially built aircraft with the same engines have gotten there too.
Here is one... http://www.rcuniverse.com/forum/fb.asp?m=381185

Beyond that... some of the FAI pylon racers and very specialty build speed ships can get to 200 mph on a consistant basis. And apparently some of the giant scale racing planes exceed 200 mph. Speed like that takes lots and lots of power.
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Old 08-25-2006, 10:13 AM
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Default RE: Predator II and Jett 50 speed

ecoliburger

I have the sports jett bse 35, 50 and 90, all perform exceptionally well with no vibration problem. In my opinion, the best overall moters out there. What else could you use on a 3d airframe, and then a high speed motor scooter. If you are looking for a fast airplane, go to the quickee 500 engines with carb and look for a formula or quickee 500 airftame that is postilng speeds at near 200 mph. The carb will rob you of 2k or so, you can option out with no control of the motor, not a good sane option in my view. You will not get much past 150 with a sports engilne and sport airframe. Matney models makes a "Animal Zoomer" that will scoot with the race wing in the 150/160 range with the Jett 50, 8.75 X 8 apc at 19K, and still land decently. If you really want to go fast only, and not turn well, watch the European speed nuts who are looking for 300 mph this year. There are several guys from Germany that are on this web that are truly amazilng in what they do, and general speed knowledge. To go fast, it's expensive and you must learn to design and build your own airframes and probably props plus gain engine hop up skills. Thanks to our lawyers, we can't sxceed 200 mph per AMA in this country. It is truly amazing how much of our society is screwed up, from medical costs to immigration, thanks to our out of control trial lawyers and legal system. Sorry, did not meen to go there. Communicate with Bob Brazil (Bobs 27) for great insite and general information in the jett engineriong forum. ENJOY
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Old 08-25-2006, 10:37 AM
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Default RE: Predator II and Jett 50 speed

hey bob Ive had my 50 with the black pipe for a few years now. Im now using it in a viper 500. the latest prop im using is a apc 7.4x8.25carbon. I had previously used the 8.75x9apc and tacking about 19,000 on the ground. with the 7.4x8.25 im tacking over 22500 on the ground and a noticeable difference in speed was seen in the air. I have a video of the viper in flight, one of thesed days ill get my lazy butt around to posting it. Your right about the speed the I would say 150 to 160 is right about where im at.



rmenke nice to see you showing up around the forum was wondering about you.



ken
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Old 08-25-2006, 03:38 PM
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Default RE: Predator II and Jett 50 speed

Thanks for the replies. The thing vibrated bad, at least it seems bad, prop is definitely balanced. It was enough to turn the needle valve, tightened it and its fine but it was not loose. I got a bubble less tank to try, hoping that may be part of the prob.


buddude8 your running a Jett 50 with 7.4x8.25carbon? What kind of fuel are you running? Been a long time since I tried to go superfast. Years ago I had a scat cat with .25 ducted fan motor and about 6" cut off the wings. Never clocked it but it seemed way faster than the predator. So 150 or so is probably tops for the Pred? I did put triangle stock behind the fire wall, etc.
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Old 08-25-2006, 07:02 PM
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Default RE: Predator II and Jett 50 speed

berger

Simmple fact of life, the "Dude" gets more out of an engine than most. You gotta cheat to beat him (cut the pylons), but thats another story. I have been running the prop Dub recommended for the 50, a apc 8.75 X 8 or 8.5 and being whipped by a K & B 48 screemer tuned by the man. Worse yet, its in a World Models Avastar with the wings cut down to 40", no front end mods!!! Just driving me crazy as the Dude can imagine. My airframe is a Matney Animal Zoomer, a cross breed of Q-500 and Foumula. Do not have something right as it wants to kiss the ground in a high speed turn. Worse, CG is not the problem, motor incidence not the problem. Going to start fresh as am being driven more nuts. I will try the Dude's prop just for the heck of it. Hope no BANG !!!!

Dude: Just can not kill off old farts like me. Have been bussy building for friends and trying to get something fast into the air. Guess I will have to bend the rules a little more. Seey ya Bud!!1
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