This is a really sweet little aerobatic built up balsa wing ARF by JR Models, purchased from NSP. As you see it, weight 32 oz. I have a Kontronic brushless 400 motor with planetary gearbox ( I think its 4.3 to 1) and controller with BEC, swinging a 14x8 folding prop, which is just a bit too big to ROG in this configuration (the motor is 6 oz, the bat 8oz). BUT - it gets thrust>weight, running 4400 rpm using the Trick RC 1700mah 8 cell packs, which as you can see are stuffed under the canopy. And a surpisingly decent run time - it seemed like 5-6minutes of full throttle. I have the prop as a folder, which makes it fly faster with the power off, and allows landing without crunching the prop.
The cool thing about this plane, besides its super fast roll rate and all around general aerobatic capability - is that it's the first electric I've played with that has enough power AND large enough control surfaces to do "hover" flight - ie, you can pull it up vertical, keep it at full or just under throttle, and with a lot of practice, get it to "hover" or do torque rolls. It takes a lot more elevator and rudder input in this mode, but it's a blast!
I had to drill out a big hole in the forward bulkhead to accomodate the motor, and shave a little bit of the foam in the cockpit to fit the battery (which still is a little too large for the canopy). The CG ends up at 80mm, which seems pretty good. Without the gearbox, running direct drive (which is a more typical config for this plane), might move the CG too far back - if you try it be careful - the specs call for a range back to 85mm from the LE. However, with the big prop, it keeps it slower and more maneuverable in the hover mode. It's also more efficient, so you get a longer run time. I may even try yet bigger props - I actually get longer flight times with this than the ePanther (direct drive), and yet it has higher thrust!
1/22/2001 - I tried a 15x15 RFM prop on it I had in the box, just for kicks. Didn't seem to increase the thrust, but increased the torque considerably. It wants to torque roll by itself in hover mode. Going to try a 15x10 next...
Stall speed is also quite slow, despite all the extra weight. Although it's a tail dragger, you can get a pretty high angle of attack before stall, which makes for nice easy landings. The only bad landing first day out (and I wasn't even flying it, so there) it pancaked hard enough to push one of the wheels up through the bottom fabric of the wing (easily repaired).
It could use more rudder - so I'll play with that. The large prop spreads the airflow out so the ailerons and elevator have more effect, but the existing rudder is better suited to a smaller prop with greater airflow. I could barely get it to knife edge.
1/22/2001 - I put some silicone lubricant on the elevator and rudder pushrods, and now the rudder has much smoother travel. It's easier to hover, as now I get a wider, quicker response to yaw. There still seems to be a little hysteresis in pitch - not sure if its sticky elevator or the plane, but more likely sticky elevator.
After looking at the JR Models
web site, I notice there are a whole line of Diablotins, of which this
is the smallest. For the whole batch, see Aerobatics.
Just after takeoff
Close up fly by - Tough to get the wholeplane in...
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