Anyone ever tried running a Ramtec fan in a Dynamax shroud?, if so was it any good?

I know it has been done. very common thing. I believe this was done for performance matching based upon the bird the fan is going into. One fan is better for heavier jets while the other is better for higher speed, but I dont recall which was which. I think ramtec was for speed and dynamax was better for heavier jets. cheers john

Ramtec fan is better all round. Dynamax was designed for 60/70 motors. It has a lower pitch so it does not load the engine too much.

With the advent of the OS 91 the engine would over rev on the dynamax, putting it out of its peak power.
The Ramtec is higher pitch and loads the OS91 perfectly, gives much better all round performance on the engine with lower rpm.

I have had a situation (years ago) where i flew a model on the Saturday with a Dynamax, which failed on me. I took the same engine in the same airframe and installed a Ramtec, overnight. The difference was staggering, Top speed was better, take off was better.

Ramtec fan in Dynamax will work but stator blades will be at the wrong angle to optimize thrust.

Hope that helps

The Ramtec fan does not work well in airframes with small inlets. It has fewer blades, but more pitch. The engine turns fewer RPMs than it would in a Dynamax.

The Dynamax (IMHO) is well suited for any airframe. I have flown a Dynamax powered Starfire at 200MPH. I have also seen a friend's Dynamax powered 30# JMP T-33, fly very well.

I have 5 Dymanax fans in 4 starfires as well as a scratch built 90 inch/25 lb Canadian Snowbird. I love the Dynamax-OS 91 combinations. I am not sure why people perceive the fan was designed for the smaller OS engines as I know Tom was thinking ahead to larger engines at the time. I am currently running in excess of 15 flights/glow plug. I use his pipe system. I have not had one dead stick in 3 years. I always set my timer at 5 min from takeoff and land accordingly with 1/4 tanks left.

If you are considering fans, I am sure they are both good. For me, I like the Dynamax for its reliability with the OS 91, the JMP system including pipe and mixture, and availability of parts (important these days). Tom is selling fans STILL!!!!

I just had to weigh in with a customer testimonial!

Dave

I'v been running an OS91/Dynamax set up for about 30 flights and the glow plug is at least 15 flights old and no sings of getting bad, speed is good, I think is all about how you run it and the fuel you are using. I prefer the Dynamax.

CARS II

At one time there was a Ramtec rotor made expressly for the dynamax housing, as a retrofit.
I had one, and it worked wonderfully in my Starfires. In the Starfire, the dynamax seemed to have a shorter takeoff roll, but the ramtec was definitly faster on topspeed. Both are fine.
Regards, Roger

I'm looking at a ducted fan conversion & can use the weight figures for the JMP fan assembled. I have the OS91 weight at 24-ozs, no pipe. Wud someone with the data pls post a response? Thanks in advance!

Phil

Attention ! The diameter of the Ramtec is a bit larger than the Dynamax. So all rotors had to be turned down (read : specified as a retrofit for Dynamax, when ordered). Same for the outer diameter of the shroud : is larger with the Ramtec.

I still have a Ramtec fan in stock (for OS 91), not even assembled. Any candidates ? Please PM me if interested.

Best regards,
Nicoals.