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Engine basics => Engine set up tips => Topic started by: Chris Wilson on August 16, 2011, 07:43:34 PM

Title: Max OS 25 VF ducted fan engine.
Post by: Chris Wilson on August 16, 2011, 07:43:34 PM
Worth a look for a fun stunt engine on a pipe?
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Russell Shaffer on August 16, 2011, 08:14:09 PM
It would probably turn a 8X8 at 25 thousand.  Sounds like a good Flite Streak engine to me. If it's cheap you should buy it.
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Chris Wilson on August 16, 2011, 09:20:48 PM
It would probably turn a 8X8 at 25 thousand.  Sounds like a good Flite Streak engine to me. If it's cheap you should buy it.
Humor I assume.
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Bill Little on August 16, 2011, 11:49:32 PM
Mike Starett published the Eliminator in Flying Models for the .25VF.  He used a .32 size pipe IIRC.  Not sure abut the "Ducted Fan" version, though.

I'm pretty sure Billy Werwage refitted a .25VF to his Perroquet.  From what I remember he liked it much better than when it had the HP .40 (muffled) in it.

I have had plans to refit Aaron's Ares with one, just no time to get everything done! LL~

Big Bear
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Russell Shaffer on August 17, 2011, 09:12:17 AM
Actually, I would expect it to turn a small prop very fast.  Something like a 9X4 would probably be in the 15K range and I bet it wouldn't take well to being loaded to a lower rpm. I have a hot rod 25 that does great on a 9X4 and is a total dog loaded down with a 10X4.  And if I was to try it, it would be on an easily built profile for experimental purposes.  Sorry if I came across as a wiseguy.



Title: Re: Max OS 25 VF ducted fan engine.
Post by: Trostle on August 17, 2011, 12:01:19 PM
The OS .25VF was intended to be used as a ducted fan engine with a tuned pipe.  According to the description of Mike Starrett's Eliminator (May 96, Flying Models) by Bob Hunt, the Eliminator was a fine performing airplane with the .25VF on a tuned pipe.

Randy Smith can do and has sold this engine with an appropriate pipe with modifications to make it more stunt friendly.  It is a really neat package.  I do not know if he still has pipes for this combination or not.

New ones are not cheap.

Keith
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Chris Wilson on August 17, 2011, 04:23:11 PM
The OS .25VF was intended to be used as a ducted fan engine with a tuned pipe.  According to the description of Mike Starrett's Eliminator (May 96, Flying Models) by Bob Hunt, the Eliminator was a fine performing airplane with the .25VF on a tuned pipe.

Randy Smith can do and has sold this engine with an appropriate pipe with modifications to make it more stunt friendly.  It is a really neat package.  I do not know if he still has pipes for this combination or not.

New ones are not cheap.

Keith
Mate, that's the answer I was looking for!

Thanks.
Title: Re: Max OS 25 VF ducted fan engine.
Post by: rustler on August 18, 2011, 01:29:45 PM
Can anyone chime in with info as to which engine is favoured for stunt? VF or DF?
Same question applies to the 40, don't know the official names, but high timed or low timed?
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Brian Hampton on August 18, 2011, 10:44:04 PM
Both the 40 and 46VF's are quite low timed being very similar to most unpiped stunt engines so I would assume that the normal 25VF is probably timed in a similar fashion. However there was also the 25VF-DF which I'd guess had much more aggressive timing for the revs needed in a ducted fan. I don't know if there are any external distinguishing features though because the OS timeline uses the same photo for the VF and the VF-DF.
Title: Re: Max OS 25 VF ducted fan engine.
Post by: Bill Little on August 20, 2011, 12:11:24 PM
Since I have never seen a Ducted Fan version of any of the VF series, I cannot say much.

However, I have used the 40, 46, and 25 VF.  All three work well on pipe.  They do tend to turn more rpm in use than the PA engines, but work great.

Big Bear