Dan,

In general, larger model airplanes tend to fly better than smaller ones. Also, a new jet modeler (especially one who's budget conscious) would be well advised to know that there are far fewer offerings in the .45-sized fan arena than the .91 sized. It makes a difference if a guy doesn't want to have to buy a new propulsion system later when he decides he wants a larger model.

In my experience, I've noticed at least as many .45-sized jets powered with larger engine/fan combos as those with the stock setups. I guess those people wanted more performance than they were getting out of the .45/Turbax setups. Indeed, they now have the .48/Turbax setups offered, with the rallying call being that they outperform the .45s. This seems a fair indication that most of these .45-sized jets could use more power?

Nobody suggested putting a .91 in a .45-sized model. You're correct that it would only result in a heavier model with a higher wing-loading and degraded low speed performance. I suggested putting a .91 in a .91-sized airplane. In this case, your concerns about fuel placement, wing-loading and performance wouldn't really be an issue. For example, a DF-powered Starfire on an O.S. .91 has a lighter wing loading than the K&B .45-powered Sabre, with considerably less takeoff distance required, and nearly twice the speed at full throttle (radar-speed). If you bumped the smaller jet up to the .48-sized setup, the go-fly prices of the two are within $100 of each other. So if the price is the same, it seems that the larger plane would be a better investment for the new jetter since he's going to have a lot more choices for his second and third jet without having to upgrade his power system.

I still enjoy flying the smaller jets. I've built several of the small A-4s by Yellow Aircraft, and even a few JHH 45-sized jets. They fly great, but the bigger jets fly better. Also, there are availability issues with the smaller setups, but you'll probably always be able to put your hands on an O.S. .91. Anyway, the gentleman who started this thread stated that he's not willing to 'spend the money' to get a .91-sized jet. If he's only getting into the small jets to save money, he might appreciate knowing that he doesn't have to.