EASYTIGER

My Feedback: (119)

another pic

EASYTIGER

My Feedback: (119)

The engine is a K&B 82, but is this fan a Turbax III, or what? Set up for belt starting, don't see any way for a spinner to fit on. I got it a couple of years ago, and I was only flying dynamax at the time, so I loaned it to a friend for his Thorpe Bros. F-104, but he never used it, and gave it back to me the other day. I don't have a specific project in mind for it, but if it is worth using, I might...

GeorgeR

My Feedback: (2)

My guess it is either a Ramtec, or a Dynamax with the spinner cone removed or modified. One has 9 blades the other 11. I don't think it is a turbax III.

Good luck,

GeorgeR.

F9F Texan

Looks like a Ramtec fan in a Dynamax housing with a home-made aluminum spacer thingy in place of the spinner.

EASYTIGER

My Feedback: (119)

Definitly not a Dynamax. Don't THINK it's a Ramtech...Shroud at least looks Turbax. I think this may be a Turbax III, which has a different rotor for larger engines than the 45 Turbax?

rcav8tr

Hi Easytiger

It's not a Ramtec shroud. The Ramtec has molded in mounting tabs.

Kind of looks like a Dynamax shroud though.

Ed

F9F Texan

Dynamax on the left

Ramtec on the right

Looks like a Ramtec which someone has cut the mounting lugs off, and installed aluminum mounts. (Note the grind marks around the mounts)
I don't know what to make of the apparent aluminum engine mount.
JA

rcav8tr

It looks like a Dynamx shroud(Note the round ribs running front to back) with a Ramtec fan(look at the two small notches in the edge of the aluminum hub, as well as the number of blades). The mounts are definitely Dynamax. Overall, it looks like its' seen better days.

Ed

EASYTIGER

My Feedback: (119)

Ed, I think you are right. That's why it seemed so odd to me. I guess the previous owner(Harry Wood of CA) wanted the Ramtech rotor to slow the 82 down a bit, maybe?
I've never flown the 82, except in the KBViolett setup. Any good? What fuel?
Say, Ed...whatever happened to the Jetstyle UK Hawker Hunter?

EASYTIGER

My Feedback: (119)

By the way, thanks F9F Texan, for taking the time to take that picture. Appreciate that.

JeffH

My Feedback: (43)

It's a Turbax shroud. It doesn't look to have enough stator screw holes to be a Dynamax. I know at one time, there was a guy that would modify dynamax rotors to fit the turbax shroud and mount. I am not sure of his name, but I saw one here locally 5 or 6 years ago. This friend had just got his modified rotor back from being modified.

Adil Nasim

My Feedback: (61)

It is a Turbax Fan with a Ramtec impellor! I have one of this and one with a Dynamax impellor. Excellent performers in any JHH airframe.

These were done so as not to modify the ducting since it is set up for Turbax fans. Dynamax or Ramtecs require a little modifications.

Hope this helps.

Adil

wsmalley

My Feedback: (6)

I have a Turbax/Rossi .81 combo I want to use and will need to use the belt start method-no room to get a starter or wand. Does anyone know if you use a cog belt of some type-or what? The 'gears' on the impellor are so far back from the rim of the shroud, I guess you'd have to hold the starter at an angle. Any thoughts or comments? Bill S.

Adil Nasim

My Feedback: (61)

wsmalley,

I've always used Prather belts - I think they are for boats etc. Having a starter on a angle is not going to work since the belt will keep slipping. Instead, take a dremel small drum sander and put two indents on top of the shroud roughly where the belt will be for clearance. It does not affect the performance and will make starting easy. Even though I don't recommend it and neither does JHH, I mostly started the engine by hand. Belt was only used on stubborn engines.

Adil

GeorgeR

My Feedback: (2)

Verdict is in, it is a Turbtec!!!!!!!

Let us know how it works.

GeorgeR.

wsmalley

My Feedback: (6)

Thanks, Adil! See, ask the question here and someone has the answer. Turbtec indeed-sure it's not a TecturbIIII?

EASYTIGER

My Feedback: (119)

Thanks, Adil. I would have sworn it was a turbax, but I did not want to dig out my Turbax from somewhere in the depths of my warehouse to compare, and I've never owned a Ramtech, and at the moment, no Dynamaxes...
How will it compare, thrust-wise, to a Dynamax shroud? Should be no real difference? I have a Cressline F-20 I could use it in, but that's a full-sized bird, and I don't want it underpowered.
This one has two notches filed for the starting belt. I don't care for belt starting, if I can avoid it. I guess I can buy the parts to turn it back into Dynamax probe starting? What's needed?
Howdy, Adil, by the way. Have not been out to the field much lately.

Adil Nasim

My Feedback: (61)

Hi Easytiger,

I personally don't think that the performance would be much different but don't have any hard data to back it up. I would think you would have a lot more air mass being passed since the Turbax has a lot less stator vanes vs the Dynamax but ...

I think the only things you would need for the Ramtec would be a spinner, long nut, and a bolt. I can set you up with these since I might have a few laying around among other Byron, Gleichoff (spelling??) Dynamax, Ramtec, turbax fans all over my basement.

I haven't been to the field lately because I put my foot down on bringing this flying season to a close. I want to make sure I finish up all my new stuff for next season. Last year I never got to put together a few models and this year I have added more like the AirMAgic F-15, GWM Mig-17, Stingray, MB-339.... Gee, I better get cranking!!

Later,

Adil

MiragePilot

My Feedback: (6)

Easytiger/Adil,

With respect to the thrust issue, the Turbax shroud with turned down Ramtec/Dynamax rotor will not produce the same thrust levels as a stock Dynamax/Ramtec rotor+shroud unit. The reason is the smaller diameter Turbax shroud. Fan diameter plays a dominant role in the max thrust capability of a ducted fan unit, and if you reduce the fan diameter, you will take a thrust hit.

I would highly recommend that you use a stock .91 sized fan for your F-20...it will need all the thrust it can get.....

Adil's comments regarding stator drag are valid however. I think it was Bob Kress who said that stator-induced drag ends up being more than the thrust increase due to the static pressure recovery function that the stators deliver..... The Viojet is a good example....only 4 stators....compared to 16 in the Dynamax!

I recall reading somewhere that back in the "Glory Days" of DF, the hottest 5" DF setup was a Dynamax shroud, with every 2nd stator removed, combined with a Ramtec rotor. On my JHH F-4, I am running an OS 91 with Dynamax fan unit with every 2nd stator removed. It hauls the F-4 around the sky with no issues, so I guess the Dynamax does function ok with half the stators......


Regards,
Peter

EASYTIGER

My Feedback: (119)

I know what you mean. Not much flying right now. I went out the other day, but I am more into the building mode. I have a few prop projects to finish up, a P61 and a Tony, then a Turbine Shrike and a turbine F-8 Crusader, plus some DF projects, I will probably treat myself to one more turbine project this winter. I got rid of quite a few kits and projects, cleaning up a bit. I am jealous of your GWM Mig. Looks really, really nice.
I may take you up on buying out some of your DF equipment. I will probably have to plunk down for a Dynamax for this F-20, I get a sneaking suspicion that Peter is right and it will need all the thrust it can get, it's a full sized 91 bird. But I may actually use this 82 in it, though when I am picking up pieces off the runway, I may be wishing I had just bought a 91...
Thanks for the tip, Peter. Neat trick, removing half the stators.