OS max VR25DF 25 ducted fan engine rear exhaust

LAST EDITED ON Jul-02-04 AT 10:05 PM (CDT)
 
I need 2 identical engines for my next airplane. I am looking for 20 size engines, nothing larger than 25 size engines. Engines with rear exhaust would be excellent. I don't know the names of engines with rear exhaust. Does anyone have a suggestion??

How many RPM's is the OS max VR25DF 25 ducted fan engine with rear exhaust? Not listed on OS web page.

What is the difference between the OS Max 25 FSR and OS Max 25 LA? The FSR is not listed on OS web page.

How fast will you be pebbling when you measure the exaust?

What are you building? The ducted fan engines are going to be screamers suited to small props. The old VF would be a better choice. And for a milder choice, and something much less expensive, you could try the Fox 25 and rotate the cylinder to rear exhaust.

LAST EDITED ON Jul-02-04 AT 10:29 PM (CDT)
 
I need the equivelent of an OS Max 40 LA engine only I want twin engines. I assume 2 OS Max 25 LA's would be equal to an OS MAX 50 LA sence 25+25=50. 50 is a little too much engine. Not sure about the old Fox 25 engines how would 2 of them compair to an OS 40 LA?

What is VF?

>What are you building?

Chances are it's a stunt version of the AF-18 in Blue Angel livery.

Microscopic razor thin wing, pair of twin ducted fans for propulsion and a tiny "Lt. Cdr. G. Weaver" under the cockpit.

Intended to show guys like Al Rabe how to build scale models that have profound stunt capabilities....

Does the term 'irrepressible' strike a chord?

Cy.

Amazing!

Because of the additional disk area of the 2 props you could use 2 .15 size engines and have more pull than the single .40. Size and pulling power are not linear. 2 thunder tigers or LA in the .15 size is what I would shoot for.

I thought that maybe you were planning on mounting these on a skate board?

Bill

>Because of the additional disk area of the 2 props you could
>use 2 .15 size engines and have more pull than the single
>.40. Size and pulling power are not linear. 2 thunder
>tigers or LA in the .15 size is what I would shoot for.

That is an interesting idea. I have a 11" prop on my OS 40. Area = pie R square. Area of an 11" prop is 94.9. The area of an 8" prop is 50.24. The area of two 8" props is 100.48 thats about 6% more than one 11" prop.

>What is the difference between the OS Max 25 FSR and OS Max
>25 LA?

The FSR is no longer being made, the LA you can buy at Tower Hobbies.

>>What is the difference between the OS Max 25 FSR and OS Max
>>25 LA?
>
>The FSR is no longer being made, the LA you can buy at Tower
>Hobbies.

Someone told me the FSR is the old version of the new FX series engines. FX is more powerful than LA series engines and produce more RPM's and its heaver.

LAST EDITED ON Jul-05-04 AT 11:23 AM (CDT)
 
>I need 2 identical engines for my next airplane.

Why two identical engines?

Wouldn't the outboard engine have to be more powerful since it has to haul its half of the airplane around a wider circle and hence travel faster to keep up with the inner part of the airplane?

Unless, of course, you are thinking of a Do 335.

Always wondering,

Cy

Identical engines sound nicer.

LAST EDITED ON Jul-05-04 AT 01:11 PM (CDT)
 
If you are planning a ducted fan stunt ship, I think there is almost no chance for success. Ducted fan airplanes use multi-blade impellers instead of props and depend, in part, on forward speed for thrust. They are not useful for static thrust. The fans are inefficient and duct losses are horrendous. Fan engines usually operate in the 20,000 RPM range to get any static thrust at all.

Save yourself a bunch of wasted money, heartache and disappointment. Talk to some ducted fan users. they are not for stunt's square and vertical maneuvers. might work OK for a scale ship.

NOPE....not planning to put this on a stunt airplane. I had heard ducted fan engines are high rpm engines and was just wondering how many rpm's this thing would turn.

>NOPE....not planning to put this on a stunt airplane. I had
>heard ducted fan engines are high rpm engines and was just
>wondering how many rpm's this thing would turn.

Quite a few, certainly enough to be very entertaining.

Buy a flywheel designed for RC boat.

Fit to your engine.

Start engine.

Be prepared to be entertained.

LOLOLOLOLOLOL!!!!!

Bigs

" What constitutes the dignity of a craft is that it creates a fellowship, that it binds men together and fashions for them a common language. For there is but one problem - the problem of human relations."

Why not mount them at the ends of a 20' long 2x6?

Bill