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May 18, 2019, 11:46 AM
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Mega Power for Electric Giants

In a few weeks, I will be looking to collaborate with more pilots who have intermediate to advanced 3D skills with 3D aircraft from 100" to 112" who are extreme electric power enthusiasts. The intent is to provide a newly developed and tested power system with a wide range of custom power options to a select few people with the airplanes I would like this system assessed with. Their only requirement will be to honestly assess the power in writing -- perhaps on this thread -- and provide at least one video that clearly illustrates the flight performance so that I can also assess the power.

Pilots do not have to be professional competitors, and don't have to be currently sponsored by 3D and XA airplane manufacturers, but all pilots with giant scale electric powered planes are welcome. Since I can't buy and fly eight to ten different planes in this size range and analyze performance based on my personal skills, it will be necessary for me to collaborate with others, so that additional feedback of the power unit's performance can be collected.

The planes I have in mind are:

AJ Aircraft 103" Slick 540
Extreme Flight RC 104" Laser EXP
Extreme Flight RC 105.5" Slick 580
3DHS 106" Edge 540 V2
Pilot RC 103" Laser

I am also open to other plane choice suggestions along the same lines of size and performance, like the new 103" planes from Skywing.

I may also be interested in 91 to 94 inch 3D planes for a smaller gear reduction unit on which I can test props up to the 26x12 size class. These props will produce 46 lbs of thrust at only 135A. The intent here is to test the much bigger prop on the planes intended for 24" props, but with fewer Amps so the flight time is not jeopardized with the suggested 12S 5500mAh main packs. The 3D performance with the 26" disk, increase in torque, and an increase in control surface authority, should be fun.

In return for the performance assessment and video, I will provide the gear reduction unit, the motor, and the ESC, at a huge discount. This discount will be as much as I can possibly offer while still maintaining my agreement with the motor and ESC manufacturer. If pilots already have either a Hobbywing Platinum Pro V4.x 200A, a SPIN Pro 200 or 300, or a Tribunus II 200A or 300A, then no new controller will be needed since all of these controllers are acceptable.

These units cannot be provided for free, but will be provided at a major discount. So the perfect scenario here is that if someone already has a giant scale aerobatic plane or is in the process of assembling one, and saving between $250 and $670 over similar power systems (depending on the size and if a custom rewind is needed) to power it with the lightest and most efficient power system available makes sense, then this opportunity should be of interest.

Please PM me if you are interested or have questions.
Last edited by Aeroplayin; May 19, 2019 at 10:36 AM.
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May 18, 2019, 11:46 AM
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R&D Background Information

For the past year, I've been involved with the R&D of an electric power gear reduction unit that can deliver comparable power of a 120cc gas engine, and potentially greater.

I felt it necessary to design and develop a unit from the ground up since a few of the existing belt and gear drive systems I tested were problematic and certainly not robust enough to manage the torque and precession of 28 to 30 inch propellers.

With the help from one of my fellow engineer counterparts abroad, I settled on a design that adhered to all the material strength requirements necessary in order to develop 12 lb-ft of torque and 14.5 HP at the shaft in a compact system that would be as easy to use and manage with 12S battery pack, just like we do on our 74 to 91 inch planes. This power would also enable the development of at least 75 lbs of statically measured thrust from the biggest carbon fiber electric prop available to us right now.

The main catalyst for the project was the fact that Falcon Hobby in China is now manufacturing 28, 29, and 30 inch light electric carbon props with the C2E designation. C2E props have always provided excellent power at a reduced current level compared to electric Xoar PJN beechwood props and other carbon props designated for electric power by PT and Mejzlik.

As of today, with the help of pilots from around the U.S., in the UK, and in Switzerland, testing of the gear reduction unit with various motors and motor Kv's has been ongoing. I now fully understand the complete performance envelope of the new system using different combinations of motors, motor Kv's, propeller brands, prop materials, and sizes.

Within the next few weeks, I am also going to be working with four more large scale electric power enthusiasts to test the calculated performance on four different motor Kv's and props on four different plane sizes and weights.

The motors have so far been tested on my personally designed and scratch-built 102" 25.5 pound SU-26 with the following configuration:

Motor Kv: 500Kv
Prop: 28x12 PJN
Volts: 44.40v
Amps: 168A
Thrust: 56.5 lbs
Non-Geared Power Equivalent: ~8485W

It has also been tested on a 105" 29.5 pound AJ-Aircraft Laser 230Z with the following two configurations:

Motor Kv: 515Kv
Prop: 28x12 PJN
Volts: 44.04v
Amps: 184A
Thrust: 60.0 lbs
Non-Geared Power Equivalent: ~9286W

Motor Kv: 540Kv
Prop: 28x13 C2E
Volts: 42.93v
Amps: 190A
Thrust: 67 lbs
Non-Geared Power Equivalent: ~9402W

The gear reduction unit is operating at a 90.04% efficiency, which is at least 11% more efficient in terms of RPM/Amp with the same prop load than the non-geared outrunners I've tested to only 7000W. This also means between 11% and 13.5% more flight time on the same batteries from the 11-13.5% fewer Amps.

The first new plane testing will match the Extreme Flight 110" Yak 54 with a 30x12 C2E to the predicted equivalent of 10.7 kW and 76 lbs of thrust at 220A.

The second new plane testing will match the Extreme Flight 104" Extra 300 with a 28x13 C2E for IMAC performance that required 9 minutes of flight time from a 12S 10Ah main pack. This will match the same 28x13 C2E with a lower Kv so that 130A can be achieved along with more than 47 lbs of thrust and a 69 mph pitch speed or an 82 mph airspeed.

The third new plane testing will match the 25 pound Extreme Flight 120" Mega Turbo Bushmaster with a 28x10 C2E to the predicted equivalent of 48 lbs of thrust at only 125A. This power setup can also spin the 28x12 C2E to about 148A and 55 lbs if needed.

The forth new plane testing will implement a 14S power system that will be matched to the PAU 105" Edge 540 with a 28x13 C2E Falcon to 165A and 67 lbs of thrust.

So several tests have already been performed with many props and motor Kv's, and four more independent assessments will soon be in progress. So the intent here is to collaborate with three or four additional pilots with different planes to close out the testing and assessment of the power system in different planes.

If you would like to participate, please PM me with the plane you have in mind, and a link to a video of you flying the same or a similar plane representing the quality of video that you can provide. It does not matter if the video is of a gas powered plane, and I'm not looking for intermediate to advanced skills. Just a good representation of typical 3D maneuvers.
May 18, 2019, 11:50 AM
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Since I'm right now using Scorpion heli motors with this gear reduction unit, it has been designated the StinGR.
May 18, 2019, 11:50 AM
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Here are two videos of Alex Barron and Mark Czechalien flying Rob's 105" AJ Laser with the 28x12 PJN.

Electrified AJ 105 Laser StingGR Alex Barron (5 min 29 sec)

Electrified AJ 105 Laser StingGR Mark Czechalien (5 min 19 sec)
May 18, 2019, 11:51 AM
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Here is a video of Rob flying the same plane with the rewound motor with the 28x13 C2E Falcon.

Electric 105 AJ Laser More Power (3 min 6 sec)
May 22, 2019, 01:22 PM
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Chris Hass is seen here flying Rob's 105 Laser at Joe Nall.

This is an incredible performance by Chris, not only because of the smooth control and well segued maneuvers, but he did this with someone else's plane and transmitter. Plus he was holding conversations throughout the flight with spectators.

Also keep in mind that with the 12S 10Ah main pack, this plane has to be at least 30.75 pounds RTF.

Kudos, Chris Hass, and thanks for making that flight possible, Rob.

Chris Hass StinGR Joe Nall 2019 (3 min 47 sec)

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