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Archive for January, 2019
Posted by rclad | Jan 16, 2019 @ 01:16 AM | 3,272 Views
To determine the minimum thrust I need (or would be happy with) for my 104" Extra 300 V2, I needed an accurate measurement of the thrust I have been getting out of my 95" Extra. The electric set up in that plane has been very good for most conditions in which I practiced and competed in 2018, flying scale aerobatics. While the thrust could have been improved with a different prop or bigger motor, that setup struck a good balance between weight, thrust and flying time. After more than 150 cycles on the batteries, I can still get a ten minute flight performing two Intermediate IMAC sequences (#IamIMAC), with time left over for extra maneuvers.

Once I knew what thrust I was currently getting and happy with, I could calculate a thrust to weight ratio, then work backwards from an expected all up weight on the 104" to calculate the minimum thrust I would need from an electric power system. Adding 2 lbs for the additional parasitic drag of the bulkier airframe should get me close to the same vertical performance I had with the 95".

After borrowing some climber's tubular webbing from a co-worker I finally had what I needed to stake the 95" Extra to the ground and run her up to full throttle. Unfortunately, the weather turned cold and more than half a foot of snow landed by Sunday morning, so I moved the test indoors. Here are the results:

95" Extra 330SC-E
Motrolfly DM5335 189Kv
Jeti Mezon 135 Opto ESC
Falcon 24x10 CFE
2x Glacier 6s 8000mAh (...Continue Reading
Posted by rclad | Jan 02, 2019 @ 08:55 PM | 3,667 Views
After purchasing my second giant scale plane last year, I hoped it would be a while before having to make another investment in a big plane. I've been enjoying flying and competing with my electric EF/3DHS 95" Extra. It's a very capable plane, and would be competitive through the Intermediate class in IMAC (#IamIMAC). I began thinking, though, that a 35% plane would perform a little better than my 30% did against the 43% giants, especially in the windy conditions that are inevitable at a contest, and be easier to see and judge.

So, here it is, another Extreme Flight plane! The 104" Extra 300 V2 will be electric powered, and it's going to carry 10,600 10,000 mAh of capacity from 35C Glacier 65C Dinogy batteries (4x 5300 mAh in 14S2P 2x 10,000 in 12S configuration) for an estimated AUW of 30 28.5 lbs. The extra capacity (over a typical 3D setup) will allow me to fly two Intermediate sequences with plenty of time to spare for practice at home, or loitering in the air for those contests that run dual flight lines.

The motor setup on this plane will use Aeroplayin's belt driven gear reduction unit, or GRU, that will allow this plane to use an inexpensive brushless heli motor rather than an expensive direct drive system. The combined weight of the GRU and heli motor will be less than a direct drive system and be more efficient, up to 91%! The numbers from eCalc indicate this setup will give me up to 10 minutes of flying time doing IMAC aerobatics.

See the pic below for my wiring schematic and components. [EDIT: See next comment with revised schematic for lighter setup.]

Stay tuned for the inevitable customization to make the conversion to electric and make life at the field easier.