ZBOB

I plan on an electric conversion of a Tiger Moth. My first choice would be a Kyosho ARF (54"ws, 899 sq. in. area, 6.2 lbs.). Second choice would be a Great Planes ARF (71" ws, 1360 sq. in. area, 10.25 lbs.) I could use some comments on this project especially selection of the motor, ESC, Lithium battery.

A confusing point is that Kontronik has an application chart that recommends the same propulsion system for both these conversions (www.krontronikusa.com). This does not seem logical to me, either the Great Planes model would be underpowered, or the Kyosho would be overpowered. Does this make sense to anyone? My previous experience is with AXI motors.

Greg Covey

Although confusing, a brushless motor has a wide dynamic range of operation. It can be used in many different size planes with different cell counts as long as the weight of the motor does not become a significant factor.

Just remember that the drag on a biplane is significant so a factor of 100 watts/ lb. will provide great performance here. This means that you'll want a motor in the 600w-1000w operating range.

The Kontronik Application chart, shown [link=http://www.kontronikusa.com/application.html]here[/link], shows 31A at 12 cells (14.4V) with a 14x8 prop. If you multiply 31a times 14.4v you get only 446 watts. For a 10lb Great Planes Tiger Moth, this only provides 45w/lb so I would not recommend it.

After using the Kontronik brushless motors, I am very impressed with their quality but have issues with their application recommendations. To make a long story short, I would use the Kontronik Brushless 600 set on either of these planes, not the Brushless 500 Set.

I have used a setup for the Kontronik 600 motor with 20 cells of Sanyo CP2400 NiCd on the 9lb Great Planes Lil Toni Racer. I measured about 41amps at full throttle using the APC 14x7 prop. This setup provides about 800-1000 watts which is the highest you can effectively go using the Jazz-55 ESC in the 600 Set. The Kontronik 600 motor, however, can handle much more than that. By replacing the Jazz-55 ESC with a Jeti 77-amp Opto ESC, you can increase the current another 10-20amps to provide up to 1500 watts of power.

Another option for battery power would be to use a 6s configuration (6 cells in series) of Lithium Polymer cells that could supply a continuous current of around 40-50amps, much like my NiCd setup. In other words, design your Lithium pack to be able to supply a continuous current value that is equal to, or greater than, the full throttle current draw. This approach ensures a safe, stress-free fit in your electric power system.

Matt Kirsch

My Feedback: (21)

ZBOB,

One thing you need to remember about electric aircraft, and this is a point I don't think Greg made, is that the BATTERY is the engine, not the motor. It's a difficult concept, because we're so used to thinking that just because it's bolted to the nose, that it's where the power comes from.

Think about it this way: An internal-combustion engine releases energy through a chemical reaction. Where in an electric power system does a chemical reaction release energy? It happens in the battery, of course

This is why, and how, a single motor can power a wide variety of planes. The motor is only transferring the power from the battery to the propeller, much like the piston, connecting rod, and crankshaft of an internal combustion engine transfer the power released by the exploding fuel to the propeller. Put a larger volume of fuel and air above the piston, and you get more power. Put a larger voltage to the motor, and you get more power...

ZBOB

Greg and Matt, thanks for the responses. You have given me quite a bit to digest, and I will.

billh

Hi! Ihave a great planes Tiger with an OS91 Surpass weighing around 11 lbs that I have tbeen thinking about converting to an electric set up, or maybe buying the smaller version anmd electrifing it. I am new at this electric stuff so I would like to hear from you as to what you end up with. Bill Hunt

Haldor

My Feedback: (5)

Note that the Jazz55-6-18 offer BEC throughout its entire operating voltage range (6-26V).

Greg Covey

Bill,

There are many ways to convert your GP Tiger Moth to electric power. Pick your motor of preference and we can help you out.

Haldor,

We would like to hear your point of view on matching Kontronik motors and ESCs. From my point of view, the Kontronik products are excellent quality and value. My issue is with the limited Jazz-55 cut-off setting and with the brushless combo sets marketed here in the US by Hobbico. I feel that the ESC matched with each Kontronik motor is under-rated and that the motor can deliver much more power than the ESC.

When I converted the .90-size Great Planes Lil Toni racer and Lancair ES using the Kontronik Brushless 600 set, the ESC could not produce over 800 watts before shutting down. By replacing the Jazz-55 ESCs with Jeti 77-Opto ESCs, the systems performed flawlessly and awed every crowd that saw the planes fly. Unlike the Jazz 55 ESC that would cut-off on a takeoff (very dangerous) the Jeti ESC has current limiting (or foldback) that is much safer for .60-.90 size planes.

Regards.

billh

Need recomendations for the Kyosho 54" Tiger. Have been reading about Orbit outrunner motors and TP lipo batteries..Cost is not a problem since at 88 I don't have time to waste. Whatever else is needed, please let me know. If there is a review somewhere it would help. Thanks again Bill Hunt

P-51B

My Feedback: (5)

I prefer to think of it this way;

The combustion engine converts fuel from the tank into RPM.

The electric motor converts electrons (fuel) from the tank (battery) into RPM.

Magna

billh

Below is my posting on the Kyosho TM conversion which I did few months back. The TM is really scale with this setup and have ample flight time even on the Gp3300 or RC2400 cell.

The phasor 45/3 on 12 cell is flying superbly on 13x6.5 prop. Can climb at about 35 degree. It can loop from level flight and do great stall turn.

I also bought an Orbit 25-18, but this one is for a 60 size conversion. If you buy an orbit (I highly recommend them), you can use Orbit 25-16 or 14 so you can use lower cell count in the region of 12-14 volts. This motor also can handle up to 18 cell for max output of 1000watts! So you can move it to other project later on.

http://www.rcuniverse.com/forum/m_19...tm.htm#1991777

billh

Thankyou my friend for the info on your conversion of the moth. It looks like I will go with the Orbit, but using lThunder Power lipo battery, but still having a separate NMH battery for receiver sand servos..This is my first time in electrics so appreciate any coments from anybody! Bill Hunt

GoodTill

Converted a GP TM a couple of years ago with an Axi 4120/18 on a Modelair-Tech Belt drive 24 cp2400 soon to be Lipo's, 18/10 prop 1000 watts and 13 lbs. Flies like a trainer.

[img][/img]

GoodTill

In flight

billh

Thankyou GoodTill! I just bought a Kyosho 54"TM for conversion since I already have theGP 72" TM on glo. The specs are around 6.5 lbs wt. and I want to use lipos. Any suggestions for a complete package woukd be greatly appreciated since I have never done an electric. Thanks Billh

Mellemel

Hi, What set up did you end up using for the Tiger moth ? I'm doing the same conversion. I have an Axi 4120/14 installed but what Lipo batteries are you using ?
Thanks.
Mel.