Best cox motor for Guillows 28 inch. Sopwith Camel (RC)

akjgardner wrote:How much does it weigh?

roddie wrote:Hi John M. and welcome to the forum!!!

I'm gonna go way out on a limb here.. because what I'm going to recommend will undoubtedly raise some eyebrows..

Try a "Babe Bee" engine with a 8" X 3" wood propeller (a Zinger if you can find one). Bush its hub-hole down to fit the 5-40 Cox prop screw. Two K & S brass tubing pcs. (telescopic fits) worked for me. I use Sig Champion 25-35% nitro which provides the necessary power and contains an oil-blend with the desired castor in the mix.

I've bench-tested that combo for a Sterling E2 Fokker DR1 (1" scale/23.5" WS) model that I'm building.



I set-up the kit's plywood firewall for both; the Babe Bee and a 2nd gen. product-engine/horseshoe-carb mounting.



A "scale" propeller for this model is 8 in. dia.



Disclaimer; The above-referenced prop will "lug" the engine. Bench-test that combo.. then remove the cylinder to check the ball & socket joint for "play". If you can't feel any play.. then you're good to go. Any play should be corrected with a reset-tool.. or else swap-out the piston/cylinder assy. from a different freshly-run engine. Lugging the engine by using a propeller that's a larger diameter than the OEM max-recommended will stress that joint... so it's better to start with a proper fit.

Engine rpm is reduced significantly.. but I flew that prop (control line) on a self-designed profile biplane; made from the Sterling Fokker kit's outlines. An RC model should work well.... and have a VERY scale-like power. It will not exhibit the shrill piercing   exhaust-note of an engine running at 15-16K rpm.. but rather a "lower tone" that sounds awesome.

The full-scale Camel's top-speed in level-flight is 113mph.. so if you're going for a realistic/scale-like experience, that would be as close as you can get.

Below youtube vid is me doing a demo of a Babe Bee swinging a steeper-pitch Zinger "8 X 4".. my muffler design and an Ace RC (Ralph Cooney designed) venturi throttle.



I also feel that much of a smaller-diameter propeller's thrust is augmented by the radial cowling. Using a 6"d prop just-forward of a 4"d cowling yields just 1" of outer-blade that's working. A 8"d prop has twice that area. Granted; there's an rpm penalty when using the 8"d but it's not a deal-breaker.. (IMHO)

Jdtamyers wrote:I’m kinda new to stick and tissue aircraft, that’s to say that the last one I built was in 1972 and it’s now 2024… So, are there any opinions on the best Cox motor for an RC conversion of the Guillows 1/12 scale Sopwith Camel.
I’m looking for the correct power match rather than looking for more time in the air… I’m trying to keep the plane light as possible but I would consider an alternate fuel tank, if possible for that aircraft??

John M

Mike1484 wrote:I think roddie is in the right ballpark on this plane. A .049 Baby Bee with a rotating exhaust throttle and a 7x3 or a 7x4 prop would be my choice. I have built most of the Guillow's 20" to 28" models for R/C and free flight and the ones with the radial engines and short noses need the tail end ( anything behind the center of gravity ) built as light as possible. Most of these kits will fly with an .020 for free flight and radio. Maybe something bigger for control line if you beef up the structure. U-Tube has some videos of this kit flying but most people use electric for their planes. hope this helps...

                                                                    Mike1484

1/2A Nut wrote:A small radial engine, perfect nose weight and sound.

GallopingGhostler wrote:Here is a free flight Sopwith Camel with same wingspan as the Guillow.
https://outerzone.co.uk/plan_details.asp?ID=3611 28in span F/F Sopwith Camel Dec 1971 Aeromodeller

Power used was half-A. The Guillow will require a certain amount of sheeting in plank on the fuselage for strength, maybe planking on wing, too, like from spar forward. Those are just a few of my thoughts.

Given that it is draggy and you want sufficient wind penetration, I'd think a .049 Golden Bee to Black Widow, or any of the modern reed valves using the extended 8 cc fuel tank would be about right. Use at least a 6x3 prop, which is optimal for these.

I have a few vintage wood Tornado Plastikote 7x2 wood props, which would put the thrust wind a bit further from the bulbous cowling. A 7x3 might be considered, but will run a little hot, need to make sure that air is generously getting to the cylinder and head's cooling fins.


Given the "flimsiness" of the Guillow rubber powered construction, if I were building, would steer clear of the larger engines, .09 and up. Those larger engines, it would be better to build from a plan that was specifically for R/C.

The OS Max .15FP is one fantastic engine, very user friendly. However, it's powerful, said to even fly a 42 inch wingspan Ringmaster with ease.

Anyway, just a few of my thoughts.

1/2A Nut wrote:A small radial engine, perfect nose weight and sound.