[Kiwi]

FLYJUNKIE.

Without trying to sound too bombastic about this I doubt you will have any problems going directly to the 50cc bird. My general rule of thumb is the bigger they are the better and the easier they are to fly.

Just follow some really basic rules when you build this thing however, and this goes for any model, brand or make.

Rule 1 is keep it light. Dont go putting 50 lbs of super duper extra large battery packs and all the add on junk that you can fill your first gasser up with. Heres a simple way to start off.

Use the best battery packs you can afford, FROMECO if available but there are others. On a 50cc kite I would use twin battery packs of around 2400 MaH each. You will fly all day with that.

An absolute must is an ignition kill system on any gas engine. For safetys sake and nothing else I beg you to put a simple sytem such as the Smart-Fly ignition cut off system in place. Again there are other brands so take your pick.

Use a good 2000 Mah NiMh battery pack on the ignition or follow the recommedations of the manufacturer. Some of the new engines can take a LiPo directly without regulators etc so go that way if you can afford it. That saves weigh as well.

Use decent servos that easily exceed the recommeded minimum torque from the manufacturer. I like metal gear digitals and wont start a brand war here by recommending anything. But the best you can afford is the goal as they can always be used on the next model if anything untoward happens to this one.

If you are still looking for an engine then go with a known brand. I see you are in England so there are plenty of makes that dont get to see much light in other lands but one thing is for sure. Dont get a magneto type boat anchor motor. Yes it will fly and you will be thrilled with it for a while. But you will soon wear thin with it as it wont do what the new 50cc motors will. If noise is not an issue go with stock mufflers. Pipes are great but they weight in so again depends on your location and the local rules.

Two bladed props generally perform better than three but again if noise is an issue go with the flow.

Keep the C of G to the manufacturers specs initially but leave the heavy stuff like batts etc with enough space to move them back as you get more proficient. Most manufacturers are very conservative with the C of G and rightfully so but dont hem yourself in with battery packs etc that cannot be relocated further back if needed. Adding weight to balance your plane is counter productive so put it together with the thought in mind that you are going to move things around inside it later on.

Hope this helps a little.
Go for it.

Kiwi