I am slowly gaining momentum towards entering rc jets with a ducted fan model. Both the clubs in my area have grass fields and that is all I'll have the option to fly off. I understand that Pusher fans generate more thrust and may be more suitable for grass fields. Insofar as many more models available today seem to be geared towards tractor fans, are there advantages / disadvantages to the ramtec or dynamax fans? My prime interest is not top speeds (I know, sacraligeous to jet pilots) but again, I am a beginner. Also as a secondary question, Flying off grass should I just stick to a pusher fan? Regardless of what type I wind up using I'd be interested in the differenced in the fans. I currently have a new in box Rossi .61. Is this enough motor for an entry level jet, or should I sell it on ebay and work at getting a .90 size engine?

thanks ahead of time.

bob branch

I have flown several Bob Parkinson Regal Eagles, a Byron F-16 and a JMP Starfire off of grass. I have never run a Ramtec, but have flown the Byron and the Dynamax. My choice is Dynamax hands down.

Grass is going to limit the number of models you'll be able to fly. Heavily loaded scale airframes with small tires should be avoided. You will need to be more concerned with weight than you would if flying off of pavement. You will also need a slightly more nose high stance, to help rotation from grass.

Here is a project (Electric F-4 Phantom) that I would have never thought would be successful off of grass. Be sure and watch the video.
http://www.rcuniverse.com/forum/m_32...tm.htm#3343697

dump the rossi for sure and get an OS 91.
On grass I would run the ramtec.
Dynamax will give you more speed in the air.
But you can always send in your fan to say A-1 hobbies to repitch the blades on the ramtec.

Hi,
If you have an OS91 use a Ramtec, its designed for it and top end is the optimum for the engine , the Dynamax was designed for the OS77(someone correct me if I'm wrong) it allows about another 2000rpm on the top end since its blades are less dense which is stretching the engine. The advantage the Dynamax does have is it allows for a smaller inlet, eg F16 as opposed to a Trim Spectre, having used both then the Ramtec is my choice if possible. In the end its far more important to spend time setting it up correctly. Mike

Whoops late here, I agree with Shok, dump the Rossi, more trouble than its worth......

SOme guys have had luck putting OS carbs on the Rossi engines. Apparently it's the Rossi carb which causes the headaches.
Myles

Jetset

How do you put an OS carb on a Rossi engine? The Rossi carb is a casting that is integral to the backplate.

bob

Hi,

Though I've long heard about the Ramtec being better for the .91, I've never seen any data to back it up. I have run both fans in similar airframes and haven't seen a performance difference. I have seen a quality difference, though, and the Dynamax seems a better built fan. Just my two cents....

Hi,
In the UK the standard set-up for just about everyone flying DF for years was OS91/Ramtec. I think that just says it all...
Mikuk is absolutely correct on the Dynamax thing.
Yes, dump the Rossi - only good for door stops! we tried Rossi engines for a little while, they were absolutely useless! We all switched to OS91's and hey, no problems. We always flew off grass with no drama. As in any other aircraft, keep it light!
Anyway don't stay with DF too long - they are fantastic and so much fun - save up and buy a turbine, you'll never look back!