Stuntin' Four Strokes?

Here's one for you guys who have been running four strokes for awhile...

When determining what displacement to use on any particular stunt ship do you go up or down or stay within the same displacement? As in, if my Nobler flys with a OS 40 FP can I run an OS 40 Surpass? If I am building a Fancherized Twister for the same 40 FP can I run the 40 Surpass instead? (I know that I can...but is the 40 FS too much?)

Will a OS 40 FS Surpass run properly inverted? even with the stock carb fixed open?

Comparatively, what would the 40 FS be like in power and torque if it were a two cycle?

Thanks a bunch, I am to the point of having to make a decision on what engine to run on two of my projects...and I have flown my cousin's Cavalier profile with this same Four Stroker and am itchin' to use it!

Hi, Phil. I did that conversion on my Euclid. Replaced an FP .40 with a Surpass .40. It did everything better. I extended the lines from 60 to 66 feet. The plane just seemed to behave better and had more line tension and less wind-up. Definitely better in the wind. I used the stock carb, wired wide open.
We compared a number of 4S .40s (ENYA, OS and SAITO) and although the OS is a bit heavier and thirstier than the SAITO .40A, it makes substantially more power. The ENYA .40 was a very old model and quite down on power.
On my Brodak Nobler, I replaced the Fox .35 with a SAITO .40A and it's a whole new plane. Didn't even have to re-trim it.
We replaced an ST .46 with an ENYA .46 4S on a Stilleto - there was no comparison - the ENYA has it all over the Tiger.
Bob Z

Perfect!

Bob, this is just what I was hoping to hear... And just the guy I was hoping to hear from!

I have a .26 Surpass that I believe was converted by you that I plan on running on a PDQ Circus King (just like a Ringmaster, only different)

My cousin is Hoyt "Hawk" Hawkins and it was his Cavalier that I flew while visiting him in Alabama this last fall...He gave me the engine off of it.

I work swing shift so I must shoot off to work right now, but I would like to call you some time. (I got your number on the classified section. PAMPA too)

Thanks again Bob! talk to ya soon...

LAST EDITED ON Apr-29-04 AT 03:42 PM (CDT)
 
Just for reference, I have the NON SURPASS version, the old 40FS in a Gotchya Streak, bigger and much draggier (is that a word?) than a twister, and probably weighs more too. I fly it with an 11x7 and it pulls it great on 10% nitro! I get 5.0 laps on 63Ft lines. Does the full pattern on 1.75 Oz fuel. Yeah you read that right. I don't own a newer Surpass version, but I hear they are not only more powerful, but also a little more thirsty than the old FS.

Mine is one butt ugly combo since the airframe saw actual combat duty in a previous life, but it's also the most fun you can have for whatever 1.75 Oz of fuel costs today! The sound is so mellow it almost puts you to sleep! Hummmmmm......all the way to the end, and then a burp, and she's done. When it's a little too windy to risk my favorite 60 stunter, I sometimes drag this little beast out and it slices up the wind nicely.

Fellow club member Warren has the newer 40 Surpass in his 10% oversize Prowler, a good size air frame to begin with, and it hauls the mail nicely too.

I say go for it!

Eric Viglione

PS - My carb is just wired open also.
PPS - I have a 26 Surpass on a Ringmaster, and it hauls it with authority.
PPPS - Also have a Saito 45 (big hunk like the 56) on a Doctor. Hauls it very nicely too.

Eric,

The Ringmaster with the 26 Surpass... Did you need to add tail weight? What is the distance from the lead edge to the prop drive?

Anything else about this set up that I need to know?

The Circus King is a Matt Kania design that had a shortened Ringmaster wing (38") but I used an RSM wing kit and built it the full 42" The dimensions are exactly the same as a RM. Only purtier, IMHO!

>Here's one for you guys who have been running four strokes
>for awhile...
>
> When determining what displacement to use on any
>particular stunt ship do you go up or down or stay within
>the same displacement? As in, if my Nobler flys with a OS 40
>FP can I run an OS 40 Surpass? If I am building a
>Fancherized Twister for the same 40 FP can I run the 40
>Surpass instead? (I know that I can...but is the 40 FS too
>much?)
>
> Will a OS 40 FS Surpass run properly inverted? even with
>the stock carb fixed open?
>
> Comparatively, what would the 40 FS be like in power and
>torque if it were a two cycle?
>
> I am a firm believer in "using what you brung." That said, run-don't walk, down to your nearest hobby dealer and purchase a Saito 40A. I almost get the feeling that Saito was secretly monitoring this forum and decided to make an engine just for us. This is THEE motor for the newbie 4 stroke control line flyer.

I just got a Saito FA40a and was thinking of putting it in an old (upright) Thunderbird. Now I think I'll actually do it.

For anyone considering replacing an OS 40 FP, or similar with a four-stroke 40: go for it!! The Saito 40 in particular is an excellent replacement, as the weight is almost identical (including mufflers). I've got an Imitation with a Saito 40 using the new Ultra Hobby manifold/venturi kit and it is a sweet combo.

I flew an OS 40 4C(non Surpass) on a Twister in the 86 Nats, then the same engine on a Thunderbird at 88 Virginia and '89 Washington. Got video of '89. I always had tank trouble and never fixed it. I think if I tried again, I'd try Larry Rengers ballon tanks. I made my own intake straight stack to boost the power of the non surpass. Its lighter than the surpass. But it was always hard to handle. Needle was very narrow and used12% to 13% nitro to boost the power. Never did use the needle to regulate power, I adjusted the nitro content.
I think the larger 4C are the way to go now. It's asking a lot to have a 40 4C pull a T-bird or something large. With the extra power of a 72 or 91, I've heard that there is power to spare.

LAST EDITED ON Apr-30-04 AT 03:39 PM (CDT)
 
>Comparatively, what would the 40 FS be like in power and torque if it were a two cycle?

>Phil Hawkins

(Snipped a bunch...)

If you're going to fly four-strokes, questions like this will merely confuse you along with giving depressing answers.

For example, the answer to your question is that a two-stroke as small as a real good 25 or 28 might well deliver more "power" and torque were it allowed to rev to the peak of either.

The primary problem is that at peak torque or peak horsepower you might not like the style of run delivered.

In general, while four-stroke 40s of today can be bolted in place of two-stroke 40s, and work well in a CL Stunt application, the fact is the four-stroke is running pinned or nearly so in order to deliver the goods. A two-stroke is merely loafing along, well below its potential.

This has been mentioned before, but my friend Pat Johnston has used the APC 13-4W on both a good ST 60 and his Saito 56. These two motors, **both in Stunt tune,** turned almost identical revs pre-launch, both give quite good results in the air. The differences are the 56 can't pull but maybe another 200 revs. The ST 60 is only a quick twist of the needle from generating a couple thousand more revs. With ease.

I suppose there's not much point to above comments, it's very much an apples-and-oranges comparison, but reference to "running pinned" is important because they are places in the pattern where we kinda like to see just a little extra grunt. Four-leaf clover, for example. With a two-stroke it leans out just a bit when you go high for entry, extra power is the nice result. Don't expect to see much of this with a four-stroke, as it is already pumping to the max.

Not mentioned by anyone are the benefits to a plumbed-per-instructions clunk tank. While I have heard of hard tanks working, in this area only one flyer continues to do so. In some cases simple substitution of a clunker for whatever metal tank worked nicely with a two-stroke results in a thank-the-Magic-Stunt-Elves transformation. (And thanks to Brett for identifying these same elves as responsible for many good things not well understood.)

People keep talking about using carbs which are simply wired open and I shudder every single time. Bad idea, at least in my experience.

Your choice, but the second time that sucker quits inverted for some inexplicable reason and you tear off the fin and canopy, you think well of me and this (free) advice.

Thanks Dan...

I was working up to the fuel tank phenomenon...

I am yet to run an FP 40. After so much talk of "run-away" I have not been in hurry to take the time to mount one up...I have two + a Tower 40 as well. I have played with a very beat-up FP 35 and it performed excellent (by my limited knowledge) on a Mathis Mongoose.

I am a person who hopelessly thinks outside of the norm. The four cycle on a Nobler gets my thrill going... Kinda like traping the cat behind the couch and teasing her with a string, thrilling with an element of danger!

On a serious note, the Surpass engines were given to me as gifts and are basically non-replacable. Plus I don't want to be blowing thru planes faster than I can build or even buy.

Fuel tank set-up's have been my single greatest challenge. I have resorted to running muffler pressure on almost everything (well OK, two MAX-S and an L&J Fox). with the exception of a Sterling Hellcat with a Fox 35 and a GRW Chicken Hopper.(Thanks in part to your advice) I have not yet mastered the 4-2 needle setting as well. Hit & Miss on that one.

One of the things I like about this forum is there are several here who think outside the norm... A couple of friends have started calling me "Philthy Phil" but don't worry Dan, you have forgotten more than I know, I am sure!