Actually, you can belly land with out ever breaking props. I do it all the time. YOu have to kill the engine before touchdown, and make sure the prop stops horizontal. There are some tricks to mounting the prop so that happens.

That said, the problem with throwing a .40 size plane is that you have to get it safely above stall speed. It's going to weight close to 6lbs. That usually requires a running start and a good two-handed shove. A powerful engine with a 4-5in pitch prop will help, higher pitch props will make it harder.

I got the number of 4-6 times based on what I've seen. I estimate the cruise speed of an Aerobird at around 8-10mph, top speed of maybe 15-20. And LT 40 would typically cruise at around 40-50, with a top speed of 60-70 depending.

You can throttle back, but a glow engine isn't an electric motor. Power output isn't linear, you don't have perfect acceleration, and it takes a noticeable amount of time to increase or decrease power. In addition, you will need full power, or close to it, on takeoff. If you hand-toss, you will absolutly need full power. The torque effects are going to be very different than what you are used to. At low airspeed and high power, the airplane will pull hard to the side.

Most importantly, the stall speed for a plane like the LT-40 is much higher than for a small electric like the Aerobird. If you fly too slow, the controls get very mushy and it becomes very easy to stall in a turn. I'd say your absolute minimum safe speed in level flight is going to be about 25mph with an LT-40. It can be flown slower by experienced pilots, but it's not easy. And getting down to even 25mph is going to take some doing. It's harder than it looks. Last week, we had a pretty good wind going at the field, so I had my students trying to "hover" their trainers. I'd easily do it with their planes to show them how to do it, then they would struggle with it for a while. It actually was a productive exercise, as it improved their landing approaches noticeably. But it wasn't easy for any of them. Lots of stalls or falling off to the side as control authority went away.