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.