Just back from testing my last motor and prop combo on my lightweight F18 V3. This time I was testing the Grayson Hobby SMJV2 motor and for the first time decided to give it a try with the 6x3 and 6x4 EMP props, just for giggles and grins!
I probably win the "bonehead of the year" award for running my plane into my leg on the first test flight on landing! I think I have most of it on video, tried to get too cute on landing, caught a bit of a cross wind and next thing I know I'm fixing my plane with hot glue and tape! Good news is other than adding a little bit of weight and character, it still flies great!
A couple pictures of the post flight repairs before the addition of some tape, thank goodness for some hot glue sticks, Bic lighter and some fibreglass strapping tape, she is almost good as new!
I was running a Turnigy Plush 40A ESC with this motor and had the timing set on medium, not for any test purposes, but mostly because I was too lazy to change it after the last two motors I tested. I have to say I was impressed by how the SMJV2 handled that timing setup, I think it performed the best I have seen it perform in a long time, so I will keep that timing set on my ESC.
The numbers from the wattmeter for the three props are as follows -
6x4 APC - 32A/384W;
6x3 EMP - 29A/354W; and
6x4 EMP - 28A/313W
The 6x4 EMP was definitely a very inefficient setup for this motor, speed was down over both the other props as was punch out power and vertical. The 6x3 EMP gave decent results, probably more efficient than the 6x4 APC for sure and decent acceleration and punch out, but not the top end speed that the 6x4 APC provided.
The weight of the plane (before repairs...) with a 2200 Mah battery is 603 gr/21.27 oz, so only 4 grams heavier than the setup with the Zoom 450 motor.
With the way I fly on a 2200 Mah battery I would get about a 5:30 minute flight with the 6x4 APC prop and about 6:00-6:30 on the 6x3 EMP prop. I wouldn't even bother with the 6x4 EMP unless it was the last prop I had in my flight box and I wanted to get a few more flights in, it is not an efficient prop for this motor, the motor ran the warmest of the three props with significantly reduced performance.
The 6x4 APC prop on this motor at this weight gave me the best speed and acceleration of all the motor/prop combos I have tested thus far on this plane, just slightly ahead of the Zoom 450 with the same prop, but the Zoom 450 runs about 10% more efficiently than the SMJV2 with this prop, so it would be down to personal preference.
I like this weight for this plane, it handles the wind the best of all the weight setups I have tested. It carries it's momentum really well and still does amazing aerobatics with no adverse affects to the handling.
So based on info that F1wanabe from the RC Powers forum passed along that 23 oz is kind of the threshold beyond which maneuverability starts to fall off, I could still build another one very light, go with the heavier setup and add in a really cool paint job and still be under 23 oz!:)
I also found out the breaking point of the Foam Tac hinges on this plane, I think I was at about the 80 flight point, the Foam Tac on the left elevon has now completely let go, so fortunately I had already reinforced it with tape. I will now reinforce every elevon hinge I make with tape just to ensure I have the strength and back up I need without adding a whole lot of weight.
The video will still be a while processing, so I will post that when it is ready!
Cheers,
Scott
Here is the video as promised.
No comments:
Post a Comment