What engine or motor for 1/5th scale Bird Dog

[David Ovenden]

I'm in the process of moving. Once settled in I'm determined to build the Marutaka Cessna Bird Dog kit I've had for so long. Waiting it's turn.

The model is 88" span and 1/5th scale. The plan shows an OS Gemini 120 twin, and the kit is designed around that engine. I have one (happily the later FT120 II version). So that's the obvious  choice. Or is it?

I also have an OS FT 160 Gemini twin. Same dimensions more grunt. Or a Saito 125 single. Or should I consider going electric? But I don't have a suitable motor or 6s/8s liposuction. What to do?

[Engine Doctor]

If you have the engine its designed for whats the problem? The 120 great , the 160 ok provided you have enough ground clearance for prop. Saito too light . Why on earth your considering buying an electric motor esc and 6/8s lipos at £100 + each unless your site has sound problems has me beat.

Go for glow . The Gemini sounds great😉.

[Jon H]

Im with ED on this one. You have suitable engines on hand so i would go with that. 

 

The model is going to be quite over powered though, which could be an advantage as you can run the 160 at very low power on a big prop. I have an ASP ft160 that i have been modifying on and off for years and it pulls my 82 inch spacewalker with no problems at all. 

 

I vote 160 gemini with probably 18x6 prop.