ORIGINAL: Lnewqban
I have made a comparison among the recommendations for 2 and 4 stroke for several of the ARF's and kits commercialized by Tower Hobbies.
The rate is about 30% more displacement up for an equivalent 4-stroke.
In this case: 0.52 / 1.3 = 0.40
Since you guys have plenty of experience with these engines, let me know of any inaccuracies you believe my chart may show.
Looks really good to me.
I don't know as much as these guys, but here's what comes to my mind:
I have 3 4-stroke engines, and I use them in 3D planes and 1 nostalgic style model. I prefer 2-strokes for general sport and high speed flying. Last year a guy at our club was hell-bent on getting max speed in his Shoestring and kept leaning out his Saito and overheating it. I think that if he wanted more speed, he should have used a 2-stroke.
I don't think adjusting the valve lash is a pain, just do it once and you will have no trouble at all. As said before, if you never have to fiddle with the needles, adjusting the valve lash once a year is a big plus (I know some guys who have never adjusted the valve lash on their engines and they still run ok).
When comparing the weights of 2 vs. 4 stroke engines, make sure the numbers include the muffler. The 2-stroke mufflers are big, fat, heavy, and ugly compared to the 4-stoke mufflers.
Despite the 30% difference in displacement to power the same model: 40 2-stroke vs. 52 4-stroke, 50 2-stroke vs. 70 4-stroke, etc... you will still get much better fuel economy with a 4-stroke.
Generally, 4-strokes are much quiter than 2-stroke nitros, and much quiter than the gassers. If people put the same muffler and noise restrictions on gassers as they did on the nitros, the gassers might not look as attractive.
Ok, I've said too much already. The three moderators can straighten me out now.