Quantcast

Moyes tempest electric conversion

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

bodex

Member
Joined
Jul 8, 2014
Messages
13
Location
Brisbane, Australia
A mate and I managed to acquire two old moyes tempest last year. Although they fly well for what they are We wanted to see if it could be converted to electric in the hope of getting a self launch from it.

Originally the idea was going to mount the motor behind the fuselage under the boom, but ground clearance was a problem. Then we thought nose mounting, ground clearance again...even with a dolly launch idea.

we then thought about a boom mounted pusher prop. Mccready used one on his human powered glider and the concept has been used before. The idea was to have the reduction pulley mounted on the tail boom using a roller bearing, the carbon prop blades then bolt to the pulley which is driven from the drive shaft below.

A few ideas and cad drawings later we had a concept and we had our machinist friend James make the parts, after removing the boom and mounting the bushing and bearing (2 day job) it was ready to connect to the engine. The power was going to come from a 150cc twin gas engine, we mounted a starter gear, clutch, and starter motor. Everything was looking good until we tried to start the motor, to much compression, so we tried auto decompression valves, still no luck.

We were stuck for ideas and I was getting frustrated with the gas engine. I had a pletenburg predator 37 brushless outrunner from my electric trike lying around and I decided to try that instead. So I removed the gas engine and 10 minutes later it was ready for a test run.

The reduction on the prop was based around the gas engine 7500rpm to give 2600 at the prop. To get this from the pletenburg required around 65v, so I decided on a 18s lipo pack. I ordered 8x 8s 5800mah packs from hobbyking and wired them to a bms in a 16s4p config to give me 23.2Ah of usefulness. The pack came out at 7kg and charges and balances through a inbuilt bms.

To control the power I used a alien power systems 450a speed controller. A linear pot running through a servo tester provides the signal. A HV contactor provides a safeguard between the battery and controller, two switches on the throttle quadrant control everything in the aircraft. A vincon battery monitor provides data on power used, current draw, voltage, time to go etc.

after installing it all we did a cofg check, originally they were really nose heavy, after installing the system cofg was around 32% Mac.

initial flight test was a aero tow, stall test was benign, power was added and a climb of 200fpm resulted, however full power wasnt available so the actual climb rate is still unknown (after landing I realized I programmed the speed controller to 18s instead of 16s so it was powering down thinking I had exhausted the battery)

more test flying to be conducted this weekend!
 

Attachments

bodex

Member
Joined
Jul 8, 2014
Messages
13
Location
Brisbane, Australia
image.jpg
Prop folded against boom

image.jpg
Ready for first test flight

image.jpg
Cockpit, tablet runs xcsoar and attaches to bluetooth vario and ias sensor.

image.jpg

Battery sits behind firewall, under wing spar.
 

bodex

Member
Joined
Jul 8, 2014
Messages
13
Location
Brisbane, Australia
Nice job! How big is that bearing ID?
It appears you have a hub around the original aluminum tube for the bearing to ride on.
Bearing ID is 110mm. The bearing locks on a tapered 2.5mm thick aluminium sleeve that has another 2.5mm nylon sleeve inside that separates the boom from the bearing sleeve.
 

bodex

Member
Joined
Jul 8, 2014
Messages
13
Location
Brisbane, Australia
Test flight two today. Towed up behind the moyes dragonfly tow plane in about 20kts of wind. Clear winter day. Released in a choppy thermal and added some power to test the motor. Was climbing nicely drawing 160 amps when there was a load bang, and then the smell of burnt electrics. I knew that noise meant a speed controller capacitor so I turned the contactor off and opened the air vent to let some air in. After landing I pulled the speedy out and loan behold it's burnt out. The alien electrics speedy is rated at 450 amp on 24s lipo so I'm not sure what happened, the speedy sits in the airflow so I'm hoping its a one off and they'll replace it.

So no flying for a few weeks, use the time to remove the main wheel and add a disc brake so I don't roll backwards when I land uphill.
 

Attachments

danmoser

Well-Known Member
Joined
Feb 1, 2010
Messages
641
Location
Sandy, Utah, USA
Test flight two today. Towed up behind the moyes dragonfly tow plane in about 20kts of wind. Clear winter day. Released in a choppy thermal and added some power to test the motor. Was climbing nicely drawing 160 amps when there was a load bang, and then the smell of burnt electrics. I knew that noise meant a speed controller capacitor so I turned the contactor off and opened the air vent to let some air in. After landing I pulled the speedy out and loan behold it's burnt out. The alien electrics speedy is rated at 450 amp on 24s lipo so I'm not sure what happened, the speedy sits in the airflow so I'm hoping its a one off and they'll replace it.

So no flying for a few weeks, use the time to remove the main wheel and add a disc brake so I don't roll backwards when I land uphill.
I admire your work on this project.. very neat set-up.

I thought Plettenberg recommends using the Jeti Spin 300 controller with the Predator 37 motor.. it should be good to well over 200 Amps

Also, the on-line specs for that motor shows 12-14 Li cells in series ..
Predator 37/6

You had mentioned using a 16-18 series battery pack .. possibly you were applying too much voltage (?)

Keep up the good work!! :)
 

bodex

Member
Joined
Jul 8, 2014
Messages
13
Location
Brisbane, Australia
I admire your work on this project.. very neat set-up.

I thought Plettenberg recommends using the Jeti Spin 300 controller with the Predator 37 motor.. it should be good to well over 200 Amps

Also, the on-line specs for that motor shows 12-14 Li cells in series ..
Predator 37/6

You had mentioned using a 16-18 series battery pack .. possibly you were applying too much voltage (?)

Keep up the good work!! :)

I had a 450a esc so the unit wouldn't be working anywhere near its max output. Generally speed controllers can't put out there rated amperage continuously and when I thought I might be drawing power in the mid 200's I ruled out a jeti 300. The motor is recommended to 14s but on consultation pletenburg didn't see any problems with the extra voltage, especially in a drive reduction, as long as cooling is adequate.
 

danmoser

Well-Known Member
Joined
Feb 1, 2010
Messages
641
Location
Sandy, Utah, USA
I had a 450a esc so the unit wouldn't be working anywhere near its max output. Generally speed controllers can't put out there rated amperage continuously and when I thought I might be drawing power in the mid 200's I ruled out a jeti 300. The motor is recommended to 14s but on consultation pletenburg didn't see any problems with the extra voltage, especially in a drive reduction, as long as cooling is adequate.
I don't have much knowledge about Alien Power Systems stuff .. looks like a nice outfit with some nice products .. I'm hoping to hear more about your experiences with their gear.

Plettenberg people reported they ran up their Predator 50/6 evo -next largest size from the Predator 37- up to 280 Amps with the Jeti Spin 300 controller and a 50 V battery.
Jedi says it's rated for a sustained 220 Amps at up to 59V.
 

renxxx1981

Active Member
Joined
Jan 5, 2013
Messages
37
Location
italy
WOW!!! I got almost an hart attack when I saw the pictures... I thought about the same concept for some time, then abandoned because too much dreamy rather than easy applicable... But then you both made an excellent work, I really love it. I was close to buy a Tempest 5 years ago from an Italian fellow who has made an engine powered conversion which -although practical- has skipped al the possible trouble by installing the prop "cantilevered" on the fuselage fore portion (not really elegant). Now it's flying in Spain according to the former owner. If any of you knows somebody in Europe with a Moyes Tempest please let me know, I'd die happy :)https://www.facebook.com/video/video.php?v=1116853292202
 

wizzardworks

Well-Known Member
Joined
Nov 8, 2011
Messages
273
Location
murfreesboro NC USA
Just a note. I downloaded the timken bearing catalog while designing my PSRU for the 6 rotor Mazda. The bearings of interest are called thin section bearings. The catalog has all the selection criteria, lubrication required and physical dimensions. The highest speed ratings are with silicon nitride ball bearings.
I really like that the motor and prop drive are mounted to the same tube. This solves a lot of the problems with belt tension from an off boom engine.

wizzardworks
 

danmoser

Well-Known Member
Joined
Feb 1, 2010
Messages
641
Location
Sandy, Utah, USA
Top