| Image Comments |
| SteveM | 14-Jun-08 20:41 |
| Testing the motor on the fuselage with 15x10 prop. I only got 380 watts but Motocalc estimated 540 watts. With the 14x10 I got 325 W and Motocalc said 420 W. The 14" barely clears and the 15" hits the floor so I may have to swap wheels. |
| SteveM | 14-Jun-08 20:49 |
| Motocalc is a lot more accurate with the Tyro power numbers so I may have some issues with the motor not being accurately modeled.
The bones weigh 6.5 lbs so AUW could be around 7.5 lbs. With the 14x10 that is ~40 W/lb and on the 15" it is ~50 W/lb. I flew the Tyro on those power numbers so I'm not worried about getting into the air. If you consider that the electric motor that I have on here weighs as much as a size 40 engine and that the batteries weigh 2 lbs then a AUW of 7.5 lbs is right where I would expect since the kit estimates a 5-5.5 lbs AUW. |
| SteveM | 14-Jun-08 22:04 |
| The motor is rated 325 Kv but I had to set Motocalc to use 290 Kv then it was spot on. I bumped the ESC timing advance to "high" and it now does 350 watts with the 14x10, which is equivalent to about 300 Kv using Motocalc numbers. I don't know what kind of tolerance these motors have so I guess I'll have to ask around on RCGroups. |
| poppy | 14-Jun-08 23:39 |
| Wow! I know electrics are quiter and cleaner, but with a glo engine, just install proper size, add receiver and servos with battery pack and go. However, I am betting that what you have will give some nice aerobatics. |
| SteveM | 15-Jun-08 01:13 |
| My understanding is that even fuel/glo engines took a while before they became fairly standardized. Part of the chaos with electrics comes from little standardization and the ability for an electric motor to operate efficiently over a wide range of RPMs.
Part of the reason I chose this motor is that E-Flite reckons it to be equivalent to a size 90 glo engine. By only running it at 20 volts (it can do up to 32) and using a 14-15" prop I only use about 400-500 watts, so there will be no aerobatics for now. But if I drop in another battery pack just like these two and size the prop to make the motor draw 50 amps (about a 16x10) then it'll be in the 1500-1600 watt range! So unlike a glo, there is a lot that goes into picking the system and there are interdependencies to be considered. And like I have done here, you can run it in a size 40 or you could put it in a 60 or a 90.
It also allows you to pick a scale prop then select a motor and battery pack to give a suitable performance with that prop. |
