I have plans for a 65"  Pow Wow (125%) with flaps, would like to put a 4 stroker in it, what would you recommend, I think this thing would probably take a .75 2 cycle.

I have plans for a 65"  Pow Wow (125%) with flaps, would like to put a 4 stroker in it, what would you recommend, I think this thing would probably take a .75 2 cycle.

Hi Bill

You can use  a  72 in it, may as well plan for that.  Is this  going to be  a little  over  750 sq in. ?

Regards
Randy

Bill:
We have done quite a few 2S to 4S conversions here, as well as purpose built 4S planes. In most cases we keep the same size or often go to a SMALLER 4S engine. Here are a few bits from our experiences with 4S.

Dan Banjock flew his Stiletto with an ST .46 and it did quite well. He then went to the Double Star .50 and he was disappointed. It now flys with an ENYA .46 4S and it is the best of the three but pulls too hard. He switched to the same lines as he uses on his piped .61 plane. Dan also competes on a national level – he now does so with a 4S plane that goes through the wind like a tractor.

Also, Dan flew a rather heavy Ringmaster in expert OTS and classic. It was powered by an OS 4-stroke .20. He was only beaten once – when edged out by appearance points.

We fitted an OS .26 Surpass to a kit-built Sterling Mustang and it did very well in PAMPA, profile, OTS and classic.

Randy Holcroft built a nice but somewhat heavy Tanager. It was marginal with a K&B .40, better with an FP .40, better yet with an ST .46. When he mounted an OS Surpass .40, it was the best of all.

Windy’s Red Baron was originally fitted with an ST .60. We converted to an ENYA .53 4S (77 ounces dry weight) – Windy said that it flew as well as with the ST.

My Euclid II was too heavy for the original OS .35S so I converted to an FP .40. It flew well but with an OS Surpass .40, there was no comparison. It now weighs 57 ounces dry. The pull has increased such that I will go to .018”/65 foot lines.
Windy converted his yellow Cardinal from an ST .60 to an OS .52 Surpass and on a very windy day at Pal Park, it flew much better than a similar plane with a .61 and tuned pipe.

My Argus was designed around a Fox .35 but I use a SAITO .30 in it. It is my favorite classic plane and it holds its own even against much larger planes.

I converted Joe Adamusko’s Polaris from a Super Tiger .60 to an ENYA .53 4-stroke. It flies with MUCH more authority. Weighs 80 ounces.

Bob Dixon switched from a piped .61 to a Surpass .52  on his Crystal and he reports that the plane flies much better

My Staggerwing has around 850 square inches and the SAITO .56 is more than enough power.

A few years back, I wrote an article for Stunt News that related our experiences with 4S engines – it was pretty comprehensive. I can e-mail you a copy if you give me your address.

Also, Brad Walker wrote an excellent article is Flying Models that really delves into the 4S application, especially if you’re interested in the large engines and competition.

Hope this information helps.
Bob Z