So I’ve made some progress on my electrification of the Mini Tyro. After a bit of maths and some guess work I ordered a D2822/14 1450kv outrunner and a Turnigy 18A Plush. The plan is to try a APC 8×4 and a 7×45 prop on it to see what power it draws.
I made a start by removing the Mills from its mount and cutting a hatch into the wood above the tank. Then the tank was removed and the tank bay floor cut away. The next step was to remove the old firewall because it was too far back to mount the motor on, I could have used standoffs but that would have left a rather small bay behind it for the battery. A new firewall was cut and installed about 3/4″ further forward than the old one. This gives a sensible clearance between the front of the fuselage sides and the rear of the prop but also has some room for adjusting the right/down thrust
As it happens the battery needs to live under the wing, but the space previously occupied by the tank is a perfect home for the ESC, with the Receiver living just behind it, slightly in front of the wing.
The battery has quite a lot of room to move around under the wing so it will need some sort of restraint, some velcro is likely. The front end needs tidying somewhat, the covering is looking tatty and I’ve yet to make a cover for the tank, now ESC bay.
Having said that, I’ve weighed it and run it up and all seems fine.
Complete airframe minus battery is 259g
The 3S 500mAh battery is 47g
The 3S 850 mAh battery is 67g
Using a 3s and the 7×4.5 prop it pulled 5.9A / 57W WOT. Giving roughly 79.3 W/lb which is probably about right for the little Tyro. I expect the 8×4 might give a good bit more and maybe even too much. We’ll see!
I’ve yet to test the 8×4 because it needs reaming out to fit the prop adapter.
I’ll post some pictures when its finished, although the temptation to fly it as it is now is quite large!