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# Extreme Electric Power - The Math

Posted by Aeroplayin | Sep 22, 2019 @ 03:42 PM | 1,198 Views
We've been actively analyzing electric power for the past 8 years on the RCG Power Systems for Extreme Flight Fanatics! thread, and I posted this about a month ago to recap some of the mathematical concepts that interrelate propeller specifications and load ratings with motor Kv, voltage, power-in, power-out, torque, and current.

For the benefit of anyone that may come by this blog, a basic understanding of algebra is all that's needed to understand these concepts. Those of us that have posted online calculators understand that the mathematical concepts that relate with each other are as follows:

Concept 1 - Efficiency:

We start off with an assumption about the efficiency of our outrunner motors and go from there. Testing will tell us exactly how efficient each motor is by comparing unloaded RPM/v against RPM/v with a recommended load. This can be affected by the ESC programming settings since it is, after all, the 'speed controller'. But if we test each example with the same controller and settings, and stick with the recommended settings, we should end up with a fair and relative comparison of motor and propeller performance.

As an example of the process of determining the Kv efficiency between loaded and unloaded (KvE), I will use a common 50cc power systems. If we have a 24x10 PJN with a typical 980 to 1180 gram outrunner that has an efficiency difference of 80%, it means that the power we put into the system results in about 80% of that power at the...Continue Reading

# Mega Power for Electric Giants

Posted by Aeroplayin | May 18, 2019 @ 11:46 AM | 2,667 Views
This thread's intent was to reach out to pilots who have intermediate to advanced skills with 3D aircraft from 100" to 112" or scale and warbird planes to 120", who are electric power enthusiasts and wished to try the new StinGR power system.

This system can develop up to 11.5 kW and turn propellers from 3-blade 24x10 props to 30x12 2-blade props on only 12S. In some instances, we're seeing between 7 and 10 minute flight times on non-3D planes.

We now have eleven different planes in the US and Europe involved with this project. So thank you all for your enthusiasm and participation. As the nine project continue on to their conclusion, I will add images and videos to this thread.

The participating planes are:

Extreme Flight 110" Yak 54 at 35.5 lbs turning a 30x12 C2E Falcon.
Extreme Flight 104" Extra 300 set up for IMAC turning a 28x12 C2E for 9.5 minute flights at 29 lbs with 12S 10000mAh.
Extreme Flight 120" Mega Turbo Bushmaster turning a 28x10 C2E for 9 minutes with 12S 6200mAh.
PAU 105" Edge 540 turning a 28x12 LF Mejzlik.
Skywing 105" V2 Edge 540 turning a 28x12 LF Mejzlik.
Skywing 102" ARS 300 turning a 28x13 Falcon C2E.
AJ Aircraft 105" Lazer 230Z turning a 28x13 Falcon C2E.
AJ Aircraft 103" AJ Slick 540 turning a 28x13 Falcon C2E.
RCWebClub 102" SU-26 turning a 28x13 Falcon C2E.
OV-10 Bronco kit 120" twin engine turning two counter rotating 24x10x3 (3-blade) Xoar PJI-E props.
Hangar 9 116" CubCrafters XCub turning one 4x10x3 (3-blade) Xoar PJI-E.

If anyone has a special project they would like to power with a StinGR unit to extreme electric power, please feel free to contact me anytime.

# 102" Purpose-Built for Electric Power SU-26

Posted by Aeroplayin | May 05, 2017 @ 02:12 PM | 13,396 Views
102" Purpose-Built-Electric SU-26 with sheeted foam wings, stabs, and turtledeck, with high density foam and 1/16th inch balsa. It's covered in genuine Oracover and the ailerons can be cut to custom sizes for IMAC, 3D, or XA. 6800W of power and enough capacity for 5.5 to 6 minutes bring the plane to an AUW of 24.34 lbs RTF.

Covered weights:

Fuse + Rudder = 2165g
Battery Tray = 83g
Firewall = 101g
Motor Beam Top & Bottom = 103g
Wing 1 = 941g
Wing 2 = 944g
Wing Decals = 99g
Stab 1 = 236g
Stab 2 = 236g
Cowl = 528g
Canopy = 267g
Wing Tube = 169g
Stab Tube = 66g
CF Landing Gear = 197g
CF Tailwheel Assembly = 57g
KavanLite 5" Wheels = 147g (stock wheels are heavier)
Steel 6mm Axles & Hardware = 32g
Hardware = 39g
Triangle Stock and Doublers = 28g

Total Empty Weight = 6438g or 14.19 lbs

We now have a new StinGR gear reduction unit on the plane too with a 28x13 Falcon C2E with a 12S 8000mAh main pack. The power unit pulls 58 lbs of thrust.

StinGR 5035 Power System = 1548g
Tribunus II 200A ESC = 235g
2x 6S 8000mAh main pack = 2215g
Falcon 28x13 C2E = 125g
Falcon 5" Carbon Spinner = 108g
AR8010T = 24g
Ultra Guard BEC Backup = 41g
5x Servos with arms and extensions = 525g

Total Power & Control components = 4.821 kg or 10.63 lbs

Total AUW = 24.85 lbs

This is an 8.32 oz/cu ft cube loading and a 29.8 oz/sq ft wing loading.
MAC * Wingspan = 1921 sq in wing area
CG at 25% Static Margin = Center of the...Continue Reading

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# PAR Calculator

Posted by Aeroplayin | Jan 06, 2015 @ 12:18 PM | 21,627 Views
Here are some quick instructions for the PAR Calculator, which is still in beta. Some formatting changes and text corrections still need to be made, but I want to complete the beta testing so I can make all the semi-final changes at the same time.

I've also included an image illustrating the measurements that are required in order to calculate PAR values. These measurements should calculate to the exact same value as if we calculated the MAC (mean aerodynamic cord) and multiplied it by the wingspan. Anything close to a 100 PAR is very good, and you should find some that will be as high as 115.

Please remember that PAR is a highly subjective ranking, and you should instead focus more on the actual values associated with them, such as wing loading, wing cube loading, power loading (Watts per pound), pitch speed, stall speed, etc.

My suggestion is to add data for your favorite planes, and perhaps establish your own PAR. Then use the PAR Calculator to identify planes and power systems that share similar values with your personal PAR.

For more information about the PAR Calculator, PAR values, or to ask about a specific motor, prop, and cell count, configuration that you may be considering, feel free to ask.

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