Long out of production, the .40VF and .46VF are still excellent PA engines. They were actually intended for R/C Pattern, and the lineup included .25VF and .61VF. A few .25VF's have been used for PA, but so far, nobody has used the .61, AFAIK. I guess there's no reason they wouldn't work ok with a good muffler, but all have been piped, that I know about. Power is fairly good, but fuel consumption isn't insignificant, with the .40 using about 6 oz and the .46 needing at least 7.5 oz, according to local users.

I recently stumbled onto a NIB .46VF at a club Swap Meet, already had knowledge of a friend that wanted one, so invested in the VF and sold it immediately for $150 plus shipping (at a modest profit). The buyer was happy, and I was happy. BTW, the box said "ABC", but as Randy Smith said, all were ABN....OS did a little fib...

Paul Walker and Howard Rush have used .40VF's for Impacts for years. The new 10g. rules don't penalize the .46 for line size, so the .46 would become more practical. I considered keeping it for a Randy Aero "Shrike", but the fuel consumption turned me off. I think the Shrike is ideal size for the .40VF (640 sq. in. if memory serves). The Impact is about 690 sq. inches, but different plans, articles, and kits give slightly different specs. The Bob Hunt "Saturn" is a locally popular design for these engines, at 650 sq. inches.  Pete Peterson's new Saturn is close to first flights, for a piped .46VF. Pete Ferguson is flying his new Impact with a piped .40VF, or would be, if he wasn't lounging around in Florida right now. Mike Haverly and I went today...Mike's old Shrike now has a R0-Jett .65/pipe in it. 

There seem to be a fair number of NIB .40VF and .46VF's out there for fair prices, so if you see one and want to try a piped setup, it's a good choice. That fuel consumption (tank size) is a problem for some designs, tho.
  Steve

Mine is running at 4.25 oz up here in Utah the 40VF or 46VF seem to run about the same fuel consumption.

Norm

Thanks, everyone for the information.  If I ever see a VF for sale, I'll know a little something about it.

Joe

Hello,

I've often read of the merits of the OS VF engines for stunt flying but don't know much more than that.
Were (or are) the VF engines specifically designed for CL stunt?  Were they offered only in a .40?  I assume these engines haven't been made by OS for some time but is there still some source for them such as eBay or swap meets?  What size       (wing sq. inches or weight) plane could a VF .40 handle?  And, if one could be purchased, what price would you expect to pay for it?

Sorry for the multitude of questions.  Thanks for any information.

Hi Joe

As you have read the OS 40 and 46 VF are good engines for CL stunt when converted from their RC carburated state, The 46 is much stronger than the 40, will turn more prop and fly larger and heavier airplanes. It is obvious that the 40 VF will pull a 700 sq in ship,  it is really more happy with more of a Saturn, Shrike, Staris sized ship. 640 to 650ish stunters. I setup a couple of hundred OS VF  engines for the stunt community and a slight edge went to the 46 for what people perferrred. The 40 VF we used 5 ounces of fuel, and  6 for the 46 VF, I don;t remember anyone have to use more than 6 ounces except for maybe Ted Fancher, Ted used many of the special 46 AAC versions that I built and if I remember correct he may have used  6.5 ounces of fuel.
 Both of these motors will produce very fine results in your airplanes  and will atke you most anywhere when properly setup. Although the VF was not an unbeatable engine, and it is not the best or most powerful 40 engine you could use the fact that Paul Walker had so much success with it has made it a desirable motor.
There are much lighter and stronger 40s that can be bought that will fly all the same planes.  If you decide to get a VF it maybe a good idea  to try to get 2 of them.
  Bill Rich used both of the and liked the  46 VF, he used it in a  SV-11  with a Bolly 12 x 4.5  3 blade prop, just as it came, 6 ounces of 5 to 10 % nitro fuel and had a nice 4-2 pattern  out of the VF, Windy even used the 46 VF for a while, and Bill Werwage used both the 40 and 46 Vf although he much perferred the 46.
Ebay and these forums are a good place to look for them, I have  many parts for the VFs engines still in stock, they are still out there if you look for them.


Regards
Randy

The one comment that wasn't made and the only drawback I know of is: These suckers are heavy. You can compensate and as is obvious, it's not a deal killer or anything, but it's something to take into consideration. Randy's PA 40 UL is something like 4 oz lighter with more power.

But I admit, there is something about the 40VF run that is hard to forget.

Anything special to do in terms of breaking in a brand new VF?  Also, is the ST spraybar mentioned in either the Impact article or Brett's recent SN article on pipe setups the same diameter as a PA spraybar?

  It's pretty close, if not the same. I would note that you can get replica ST spraybar assemblies from a lot of people, including Leonard Neumann. I think the PA is probably better but for the VF the vibration issues you sometimes get with the ST are not common.

     Brett

Just fly level for five laps or so before you start a wingover.

Oh, that's just harsh! They need to be broken on a stand with one gallon of 29% all castor fuel. 

Also, Mr. Walker leaves out a couple of steps when he describes his VF mod procedure.  He says just to take it out of the box and put it on the airplane.  In reality, you have to take it out of the box and install the stunt venturi and needle valve assembly.  Only then can you put it on the airplane.  

      My kind of modification - modify it's position from in the box to on the airplane.

      It's a darn weird world we live in where rank beginners desperately seek highly modified engines and 10-time NATs champions use them as they come from the factory. Dirty Dan had to invent "BBTU" so that everybody would think it was cool enough to use.

   Saw the same thing in motorcycle racing. There was a story in some motorcycle mag in the mid-70s about some privateers who had the garage next to the Yamaha factory Team/Kenny Roberts. The privateers were running some super-modified cylinders, but they scored their last one. The Team Yamaha lead engineer saw their plight and asked them if they wanted one of Kenny's old cylinders (used in the last race, which of course they had won, and carried as a spare). Of course they said yes, and were really excited, man, they are going to get some super-high-zoot parts straight from the factory, gonna be something special. Then they looked at it, and it was exactly the same as their cylinders - BEFORE they had "hopped it up". And they picked up 1/2 a second a lap.
 
   R/C guys have been a good source for motors, too. My favorite VF was purchased from an RC guy who sold it to me "for parts, it's burned up". I then proceeded to fly it at every contest from about 1990-1998 on and qualified at the NATs 6 times.

   BTW, for everyone reading, Steve is KIDDING, don't run it for an hour on the bench with Fox Superfuel, that is, unless you just enjoy crock-potting your brand new engine. Or running it for another 2 gallons with helicopter fuel to clean it out.

     Brett

  BTW, for everyone reading, Steve is KIDDING, don't run it for an hour on the bench with Fox Superfuel, that is, unless you just enjoy crock-potting your brand new engine. Or running it for another 2 gallons with helicopter fuel to clean it out.

Ooh, heli fuel. I like it!!!

I also recommend mixing some nickel powder into your fuel during break in to glaze the cylinders. It will improve launch RPM's by 10%. How do you think they nickel coat cylinders at the factory? 

Steve

P.S. I try really hard to restrain myself but then "bad Steve" comes out and messes everything up!