Primary Force and OS FS26 4 Cycle

Today, replace my LA25 or a OS FS26 surpass. I flew my P-Force with an OS FS26 Surpass and I really like the feel. Tried various prop, seem to fly best with a 10 X 4. Lap time about 4.9 but it doesn't seem fast. Still, I think it lack a bit of power in vertical manuevers.

I am wonder if a Saito 30 is the same bolt pattern as the OS 26. I am think about putting either an Saito or the new OS FS 30. Does anybody know if these engine have the same bolt pattern as the OS.

Heman,

Hey, thanks! I just posted a snide comment about your handling of the 25LA and you don't even have it on the model any longer...

Hit your existing four-stroke, unless you have given up on it in the last 4 minutes, with more nitro prior to going to the expense of buying a bigger engine.

>Today, replace my LA25 or a OS FS26 surpass. I flew my
>P-Force with an OS FS26 Surpass and I really like the feel.
>Tried various prop, seem to fly best with a 10 X 4. Lap
>time about 4.9 but it doesn't seem fast. Still, I think
>it lack a bit of power in vertical manuevers.

If you aren't running a clunk tank, by all means go get one. It's like magic on the 4-stroke, and seems to solve exactly this problem.

LAST EDITED ON Mar-14-04 AT 09:13 PM (CDT)
 
I am going to try that next. I don't know why it would work.

Larry Wong and I have been playing around with the 4 stroke for the last couple months. We both have a FS 40 Surpass. I notice a few weeks ago, he had his running premo, especially after he purchase some YS20/20 fuel.

He still has the standard vented tank on his, so I looked at what he did in term of venting. Basically he did nothing, no muffler presure, no uniflow, no 45 degree cut in the fill or outlet tube. Also, I notice Ted, still has a standard metal tank on his Doctor with the FS40.

Therefore, reluctantly I took the uniflow plug off and left both uniflow and overflow open with no presure. Wow, I was finally able to get a full flight in. At least we solve that problem.

Is there something about the flexibility or shape of the Clunk tank, that makes it work better for the 4 cycle?

>I am going to try that next. I don't know why it would
>work.
>
>Larry Wong and I have been playing around with the 4 stroke
>for the last couple months. We both have a FS 40 Surpass.
>I notice a few weeks ago, he had his running premo,
>especially after he purchase some YS20/20 fuel.
>
>He still has the standard vented tank on his, so I looked at
>what he did in term of venting. Basically he did nothing,
>no muffler presure, no uniflow, no 45 degree cut in the fill
>or outlet tube. Also, I notice Ted, still has a standard
>metal tank on his Doctor with the FS40.
>
>Therefore, reluctantly I took the uniflow plug off and left
>both uniflow and overflow open with no presure. Wow, I was
>finally able to get a full flight in. At least we solve
>that problem.
>
>Is there something about the flexibility or shape of the
>Clunk tank, that makes it work better for the 4 cycle?

Hard to say, but it appears to drastically help the fuel draw. I had no idea, Godzilla got Jim Aron to try it at the NATs a few years ago and it was close to a miracle.

For any 4-stroke, the VERY FIRST THING you need is a clunk tank.

> For any 4-stroke, the VERY FIRST THING you need is a
>clunk tank.
>
> Brett

True, True, True,...

My venture into the 4 stroke craze started with a Saito 30 on the TwistMaster. I was convinced I could make it work with a hard tank to the point of building 3 tanks and wasting 3 good weekends messing with fuel, props, tanks and less than desirable engine runs.

The problem was just as described, seemed to run pretty good but it lost power overhead. I even built a hi zoot chicken hopper that I absolutely knew was going to work, how could it not work the hopper would guarantee consistent fuel delivery.

Finally, I got my head out of the sand, listened and stuck on a 4 ounce clunk. The tank was plumbed per the Sullivan instruction sheet, one vent and the clunk, that's it.. nothing fancy.. Wow what a difference, the "I think I can" over the top turned into "Hey this is no problem what do you want next"...

There has been many discussions on this subject over the past couple of years and I am not sure anyone fully understands why it works, but it does work.. Don't waist good practice time like I did just do it....

LAST EDITED ON Mar-15-04 AT 12:59 PM (CDT)
 
Do you bend the vent toward the airstream or is it just straight up? Or, does it make any difference?

What shape cluck tank or does it matter? There is round, square and slanted.

>Do you bend the vent toward the airstream or is it just
>straight up? Or, does it make any difference?

My Impacts have vent line hooked up to fuse-mounted piping and they just face forward, per normal practice. Try it both ways, noting that with a clunk tank, a four-stroke and even 1/2 ounce of fuel you'll have time to fly a bit, yet not fly so long as to hurt anything
>
>What shape cluck tank or does it matter? There is round,
>square and slanted.

I would like to suggest that you use a round clunk tank as it is quite a bit more difficult to mount securely to a flat fuselage. Hey, how about drilling a big-### hole in the fuselage and mounting tank laterally?

Or you could do it the easy way. Wimp.

A DuBro 4 oz. or a slanted Sullivan will do jus' fine!

Here is my friend, Larry's setup. His setup uses a uniflow tank, but not the standard uniflow setup. Overflow is not capped. We tried the cluck tank on his model and it did not work. It actually did the opposite, lost power in manuevers.

I still have the standard vent tank on mine. I adding a short tubing utilizing a 45 degree cut in to the airstream on both overflow and fill vents. Performance was improved, but their is still room for improvement.

Sorry for being stubborn about going to clunk. I want to try a few more variation before going to clunk.