Hi friends,

I have a RCM F-18 prop jet. This jet was designed by Mike Pastro in pusher configuration. Mine have a OS 91 vr-df with a 11x9 prop in nose, this thing is fast, but i have an obvious problem, the plane needs 30 oz on tail for balance! Is heavy and tricky on landings.

This jet is not suitable for ducted fan, so i thought to put the engine on tail like in original plans, but i have not a pusher propeller for this vrdf. Instead i have a Byron rotor.

Can i use this Byron rotor has a pusher propeller, or it will need a thrust tube and stator?

If need a thrust tube how much is the minimum tube large?

I have no experience in ducted fan, so i need your help.

Thanks in advance.

Javier

Are you mounting the motor in a Byro fan unit or just using the rotor? If you have the entire unit, it should work fine. You don't even need a thrust tube.

Shaun Bell

Thanks for reply.

I have not the byron complete unit, i only have the rotor.


Javier

I have heard that the Byron rotor makes a decent pusher prop, although I have never tried it.
With the fan housing and a short thrust tube (~ 8") it works very well on my Enforcer. You can always try the Byron rotor and if it doesn't work out buy a pusher prop. I'd be concerned about the hub strength on a pusher prop if you are going to be turning it at 20K. If you go that way I'd recommend buying a large pusher prop and cutting it down to the desired diameter.

Joe

Is very difficult to find a pusher propeller with the correct pitch for this engine. But, if i make a glass fiber shroud, it will need the stators to run properly?

Thanks

Javier

Finally i did it. I fit the Byron rotor on tail (OS 91 VRDF and Weston mini pipe), no stators, no shroud. It was a total waste of noise and smoke!

The jet begun the take off run like a heavy truck, 60 ft where not enough to reach a decent speed to airborne.

So i will try a pusher propeller, but here is difficult to find one for this engine (91 VRDF), does someone knows if this engine can run backward in order to use normal propellers in pusher configuration?

Thanks in advance.

Javier

Since the engine has a removeable backplate/drum rotor, you should be able to rotate the backplate 90 degrees counter clockwise (when viewing the backplate directly) this should make the timing correct for reverse rotation running.

(I may have the direction you want to rotate the backplate wrong, but it is simple to see with the engine in your hand as you want the rotor to open up as the piston starts on the upstroke)

AJC

Thanks for reply AJCOHOLIC i will give it a try...

[quote]ORIGINAL: Javier-RCU

Finally i did it. I fit the Byron rotor on tail (OS 91 VRDF and Weston mini pipe), no stators, no shroud. It was a total waste of noise and smoke!

The jet begun the take off run like a heavy truck, 60 ft where not enough to reach a decent speed to airborne.

So i will try a pusher propeller, but here is difficult to find one for this engine (91 VRDF), does someone knows if this engine can run backward in order to use normal propellers in pusher configuration?

Thanks in advance.


What was your RPM ? Did the engine come on the pipe ? it SHOULD fly the plane good. Without a shroud or stators.You should be turning that rotor at least 19,500 rpm.

Jackjet

Hello JackJet

I can not read rpm on the rotor, but by sound i am sure the engine reach peak rpm (91 vrdf with Weston mini pipe). May be i was wrong because i fit the rotor in a short shroud (3" length).

Anyway, i think the prop could give more thrust than the rotor, what do you think?

AJCOHOLIC, last night i tried to rotate the backplate 90 degrees but was not possible, due to mechanical lock that avoid the piston to full down when the backplate is in new position.

May be i don´t understand you? or there is some machining or modifications necessary?

Thanks in advance for your help, i have a contest next sunday and would like to fly this jet.


Javier

This diagram could illustrate better...

I didnt hink of that problem, I was thinking of a rear disk or rotor which exits through the center... oops. The OS with the exit out the side will need a mod, something like a new drive hole in the rotor, but that would require a rotary table and accurate layout/ machining.

Sorry about that..

AJC