OS 46 VX DF engine conclusions
 

I’ve come to some conclusions about the OS 46 VX DF engine. Its power is truly awesome, easy to start, idle and transition. The engine has some definite things you must consider when it is to be used in a prop plane. This engine is very limited in the prop that you can use. In order to install a prop you must use a short shaft adaptor which means the hole in the prop must be 3/8” diameter this effectively eliminates safely using all 9”sport props with their small hubs, even if you intended to keep it in it’s safe speed range. I have not had much luck carving down 10” sport props with its much larger hub so that pretty much leaves the pylon props, the gray glass filled and the black carbon fiber types. I tried the gamut of the gray type from 9 to 9.75 pitches, all with the same result…the blade tips come off. I even trimmed the diameter some with the same end result. This engine has more then enough power to destroy all APC grey pylon props at will.
I had convinced myself that the Diamond Dust needed more diameter than the carbons came in but this is all that I now had left to try. So I shortened the pipe a tad so the 7.4 X 8.25 carbon prop could wind up to 24,500 on the ground and god knows how high it unloads to in the air. Well life is full of surprises because the DD is a heck of a lot faster than it was with any of the grey props, so much faster that I’m barely able to stay ahead of it. I never thought that day would come, but it’s here. The carbon has over 25 flights on it now and it looks great.
My conclusion;
Because of prop limitations, this OS 46 VX DF engine is best used in a very clean plane like a Strega 45 (Look’s project), Quickie 40 or a Clipped wing Diamond Dust (at the dirtiest). If one was to tone the engine down to lower rpm applications, it would be unpractical. A fast sport plane would be better off using a Webra, Rossi or Jett that have smaller prop shafts, more usable power band for available props, much lighter weight and better fuel efficiency.
Got another surprise, long life glow plugs!
The same glow plug has lasted me 17 flights and still counting, using up 8oz. per flight, that’s about 1 gallon of 30% nitro at over 25,000 rpm. The glow plugs are K&B, Type HP high performance Long Reach (#7300) Description: “This is a favorite for both Airplane and boat racers using more than 25% nitro. Works great in ducted fan engine too.” http://www.mecoa.com/acc/glowplug/glowplug.htm
This Diamond Dust now has over 50 flights on it, 25 with a new engine/carbon props. The other engine was used and got some lean runs/thrown tips and I guess it was just too much for the bearings. That engine is together again and waiting next to the other two.
The clipped wing DD is harder to launch than the standard version but I got it down to a science now.

Just some of the blown props and the good carbon.

RE: OS 46 VX DF engine conclusions
 

We want a video. :D
Edit - Great information on that engine also.

RE: OS 46 VX DF engine conclusions
 

it looks like the engine wanted that diameter prop and was prepared to rip the tips off of bigger ones to get what it wanted.:D

nice report, filed away for reference for sure

RE: OS 46 VX DF engine conclusions
 

Me too!:)
I need to find a camera man that can keep the thing in the frame and brave the heat. At our field (east facing) you dont fly till the sun is high enough that it dosent blind you. By that time it's over a 100* After the hot spell perhaps. I flew it twice today and said screw this, as the sweat kept running in to my eyes.

Thanks guys.

RE: OS 46 VX DF engine conclusions
 

Short version: It kicks ass, and use a carbon QM prop!

Cool, good info.

MJD

RE: OS 46 VX DF engine conclusions
 

Yup, but I had to find out.:D

RE: OS 46 VX DF engine conclusions
 

Thanks for the info FF. The .46 DF engine sounds like a lot of fun, especially if you can get that much performance on the same plug.

RE: OS 46 VX DF engine conclusions
 

FF: did you make your own prop adapter or did you buy one? Also, what kind of pipe would you recommend or did you use? I am thinking about putting one of these in a 40 size F-20 that's still in the kit. I want to get my motor before i start building the kit so I can make it fit properly. I am not looking for a 200mph plane but something in the 150mph ish would be fine.

Thanks.

RE: OS 46 VX DF engine conclusions
 

I am not a big fan of OS however any engine that will rip the prop tips off an APC gets my vote [sm=thumbs_up.gif]

K&B HP plugs also work great in Rossi's on 10% nitro, been using them for 7 years now and they keep going.

RE: OS 46 VX DF engine conclusions
 

Ramz-to-tha-z

You can use the Tru Turn part number TT-0141-A. Mac’s pipes and headers are what I use. The #1050 Quiet pipe, #1250 Muffled (Best performance) and the 1150 tuned (noisy) The best average pipe setting was 9 ½” to 9 ¾” from center of piston to the large diameter (apex) on the pipe. Put the pressure fitting near the apex.

I don’t know if this is the best engine for the F-20 platform, I think you’d need more disc area. I’d be leaning toward the Webra 55 & red Jett muffler with a 9X10 apc on 10% max (9X8 break-in on ground, WOT, two stroke rich, extra caster).

Rossi 53 (10%!) or Jett 50 or 60 LX with a sport prop would be the ticket too.

RE: OS 46 VX DF engine conclusions
 

Thank you very much for your info. I haven't decided on anything yet but I'm leaning towards the OS VX-DF 46 on an Outlaw. I may put the F-20 on hold for a while.

RE: OS 46 VX DF engine conclusions
 

Waaaaaaaaaaaay too much engine for an Outlaw and Waaaaaaaaaay too heavy. That DF engine weighs much more than other 46 size engines and a light 46 is still too much.
A Webra 36 is perfect for it. You'd need a ton of lead on the tail if you put a VX in that and a 1 minute flight with the fuel tank that it has.
The Outlaw is a quick, agile delta it's not for real high speed.

RE: OS 46 VX DF engine conclusions
 

New video, havin fun.:D
http://www.youtube.com/watch?v=5m0t925_elc

RE: OS 46 VX DF engine conclusions
 

Cool video freakingfast also too many Gs there :D

RE: OS 46 VX DF engine conclusions
 

Thanks Speedboy.
I just luv it when I hear the air complain[>:]

RE: OS 46 VX DF engine conclusions
 

That video doesn't do that thing justice, it SMOKES and FF does a HELL of a job on the sticks.

RE: OS 46 VX DF engine conclusions
 

I don't see any one disputing that. :) As far as smokes, it did have a smoke trail. Wonder if it could have been leaned a bit more?

RE: OS 46 VX DF engine conclusions
 

It's running on 30% heli fuel and the extra oil leaves a good smoke trail. Leaning it out more won't gain anything in power, it's there now. I know this because the high speed screw would turn itself in and go lean, I put a mini tie strap on the spring clip and screw to stop it. Haven't tweaked the needle in a month. The header could be a tad shorter, but I've been done with messing with it for quite a while now. If it aint broke.......... I just want to fly the snot out of it.[sm=lol.gif]

Amazingly this thing is low maintenance. When I'm done flying, I empty the tank, refill it 1/4 full with FAI fuel, start & warm it a moment and run it at WOT for 30 seconds, empty the tank, run the engine dry and spin some after-run through it. Wipe off the oil top and bottom. When I get home it goes on the charger (a fresh charge is good for 10+ flights). I inspect the linkages for slop, if there is any (about 30 flights), I clean the connected linkage with alcohol and blow it out with air. A very small amount of CA is put into the connected linkage and hit with kicker. After a moment I grab the servo arm and control horn to free it up. Presto, zero slop. I change out the glow plug every 1 1/2 gallons because performance begins to degrade. That’s it.

RE: OS 46 VX DF engine conclusions
 

Dumb speed plane rookie question - why the FAI fuel? Just getting rid of any leftover nitro?


Mark

RE: OS 46 VX DF engine conclusions
 

Exactly, I’m convinced that I can’t just run it out of fuel and use after run oil to get rid of the nitro. I found that if I don't flush it with FAI fuel, a few days later there is a very subtle gritty feel to the bearings. I’m thinking that these are little rust spots on the balls and races from acids formed by leftover nitro residues.

Thats my story & I'm sticking to it:)

RE: OS 46 VX DF engine conclusions
 

Correct,

the oxidative nature of nitro fuel to most metal surfaces (ferreous, aluminium, brass) should not be undervalued.

For instance there are R/C speed boat classes using > 50% nitro fuels. These engines have to be “cleaned“ internally with straight FAI fuel (80/20) after each race.


Procedure:

Most important is that the engine has to be “afterrun“ with the zero % nitro fuel at hot operating temperature. The high internal engine housing/cylinder/bearing/crank etc temperature together with pinching-off the fuel delivery at full throttle ensures complete evaporation of all nitro and methanol residuals within the engine.

After that zero nitro afterrun procedure only the lube oil is left within the engine being a perfect conservation until next week’s operation.

Additional special afterrun-oils are not necessary as a rule.

RE: OS 46 VX DF engine conclusions
 

Hey Frickin Fast,
Where is the video?
Youtube says it is no longer available?

Now it is back up[:-] - go figure......

Good info on the FAI fuel gents, Thank you!

What size fuel tank are you running?

I love the dual purpose handle[8D]
Rob

RE: OS 46 VX DF engine conclusions
 

It's an 8 oz. Sullivan SS-8 tank that’s good for 3 minutes a WOT so set your timer to 2 minutes 45 seconds. The tanks bottom is on a 1/4" sheet of Du-bro's foam rubber and smaller pads around the sides keeps it isolated. I run an OS #71531000 Non-Bubble Weight (clunk).

Yup that pipe coupling is the perfect balance point for a launch handle, unfortunately it gets too hot to handle (sorry);) in about 45 seconds. I use a glove now because I have touched the pipe[:@]

RE: OS 46 VX DF engine conclusions
 

Why is it, that every time you think you have a great idea, you find out someone else thought of it first? Oh well, at least it confirms my theory. :eek: Thanks for the info Jets.

RE: OS 46 VX DF engine conclusions
 

Because it is a good idea with sound reasoning behind it. Just take credit for thinking about what you are doing and coming up with the idea independent of anyone else!:D

Mark