Jlbrad1

I am interested in converting my Sr Telemaster to electric and need a little guidance. I have reviewed a few sites and threads but still a little confused.
Specs on plane:
Weight - 7lb (no motor, just RX, RX batt, servos)
Length - 65"
Wingspan 96"

I have looked at the AXI 4130/16, just not sure of the setup (ESC, battery, etc..)

I am new to electric, have a few park fliers (pre-canned motors, batteries, and ESC). I really enjoy the convenience and no mess. I love my Tele and want to get it up on some green power.

There is a combo on maxxprod.com/mpi/mpi-264.html (Combo 60A) that looks to be suitable.
Motor -HC5030-390
ESC - Castle Creations 75 Phoenix Ice 75A
Battery -? I would like medium to long flying times
Charger -?

I will be towing a sail plane at times so the motor in the combo 60A should have the extra torque i would need. I will more than likely spin a 14X10 prop.

If I go with the combo 60A, any direction on the battery (lipo) and charger setup would be greatly appreciated.

Thanks,
Jlbrad1

Saddlebum

Jbrad1, nice to see your post.

I am doing exactly what you are doing, as we speak. Just about to open the box to start.

I went with a .60 size equivalent motor, 80 amp esc, probably a 14x10 also (but that will be finalized after some wattmeter testing).

My battery choice is a 5S, 5,000 mAh Turnigy Nano-Tech. My motor can handle the voltage.

I plan to start flying on one battery to measure the time in the air then (perhaps) add a second battery in parallel to double the flying time.

I am a strong believer in FMA products and use their CellPro 10S charger for all my big LiPos.

Links are included in blue, above. Keep me posted on your progress and I'll keep you posted on mine.

...The Bum

BEAR-AvHistory

SR. TELEMASTER
SK-5055/580
Turnigy Cherry 15X8
1237watt @ 66amp
MAS 13X8X3
1100watt @ 59amp
MAS 14X8X3
1377watt @ 77amp
5S5000

Motor will take more battery up to 8S & is rated for 1580watts on a 15X9. That being said this one has very rarely seen more then 50% throttle.

Saddlebum

The 13x8x3 draws the least wattage. Interesting. How's the performance with the 3 blader, Bear?

...The Bum

Saddlebum

Hey Bear; three questions if you don't mind?

1. How did you get the decals off? Simply peal'em or did it take heat?
   
2. Did you build a "box" for the flight battery? The floor just ahead of the cabin looks to be thin ply. Doesn't look strong enough to me.
   
3. What did you do about attaching the struts? I'd like to leave'em on the (2 piece) wings but find some cleaver way to fast release them from the fuselage. Any ideas on that?

Thanks for your input... The Bum

Jlbrad1

Thanks for the quick replies and the information. This information helps in my quest, it also tells me there are some better deals on the performance and hardware I am looking for.

Bear, what kind of fly times are you seeing with this setup.

Bum, will do. I might be bugging you for some pointers.

BEAR-AvHistory

The decals peal off pretty easily.

I put a new 1/8" floor in from just in front of the servo tray to just short of the firewall. Will hold a 5S5000 in the CoG balance position.

Battery is loaded through front cowl hatch. One picture shows the wing end of the strut which stays attached. The other one shows, not all that well, the ends of the belly strap & the quick release pins that go through the fuselage end of the strut. The white squares are velcro on the back end of the battery floor. Can take some better ones in the morning.

The fuselage end of the strut was wrapped in Kevlar thread which was then soaked in thin CA. I put some black shrink tube over it to make it look neat then drilled a hole through it for the pin that goes through the belly strap. The wing end also has Kevlar thread & shrink wrap but the clevis is attached to a piece of pushrod in a hole drilled into the the end of the strut.

Not sure how long it will fly. I set my timer for 8.5 minutes but generally will fly past it. Ten minutes is no problem. Plane is very stable, had a radio issue & it landed itself with no damage on the fail safe settings in a farm field next to our flying field.

It weather vained around 90 degrees in a light breeze from where I lost it & made a really good landing. The guys suggested that I should make that my normal procedure.

Odds & ends in the picture are a "Be Found" beeper on the right wall, rudder gyro (blue box) & the back end of the bolt on wing modification (front uses a tongue & slot arraignment). I use the Telemaster for a lot of my "I wonder what this will do" experiments.

As for prop performance I really cant tell all that much. Its said that the 2 blades are more efficient but I use the Cherry wood 2 blade as my main prop because it looks nice. The plane has flown a lot the the 13X8X3 because I did not like the current draw on the 14X8X3 since I use a 80amp ESC which is recommended for this motor.

cliffh

I've got around 100 flights on my Senior Telemaster with the following setup:

motor - Turnigy SK50-55 580kv
esc - Turnigy Plush 80A
prop - Turnigy Type A 14X10 beechwood
bec - Castle Creations 10A
battery - 4S 5000mAh

Volts - 15.4
Amps - 58.5
watts - 900
AUW - 10.5 lbs with 4S 5000 battery

The plane can get off a deep grass runway in around 10'. Seldom use full power, even on takeoff. Usually just over half throttle.

Most flights require around 3500mAh to top battery off after a 10 minute flight. Battery, motor and esc always come back cool. I mounted the esc under the motor in front of the firewall. Fits perfect and is in the airstream.

The plane could EASILY carry a second battery in parallel for 20 minute flights.

Great airplane!

Cliff

Saddlebum

GREAT stuff Bear and Cliff.

Thanks!
...The Bum

cliffh

Hey, by the way, any unwanted stickers can be peeled off very easily. The only trick is to take your time. Pick at a corner with your fingernail until you can pull it, then pull v-e-r-y s-l-o-w-e-l-y. You will feel it loosen with only a very gentle pull, but it will be slow. Let it come off at its own pace. I was suprised at how easily they did come off and yet the ones I left on stick perfectly.

Cliff

kyleservicetech

You'd want a motor with a fairly low KV rating so you can turn a large diameter prop at fairly slow RPM. Something on the order of perhaps 6000-7000 RPM.

I've got a Hacker A50-16S motor that turns a 16X12 APC-E prop at about 6000 RPM, pulling about 50 Amps on a 6S2P A123 (2300 Mah cells) for a battery pack with 4600 Milliampere Hours. The model is a "Showtime 50". Flights are very nice, and it will fly 8 minutes, using about 60% of the battery.

If you've not used it before, check for various electric model spreadsheets that will help in your decision. One I've been using for years is www.motocalc.com. That program is free for 30 days, then its $39.00, and worth every penny.

If you decide to try different props, be sure to pick up a wattmeter, such as the Astroflight whattmeter. It is very easy to overload an electric motor with an oversized prop. The first you know about it, you get smoke, from your motor, ESC, battery, or maybe all three.

Saddlebum

YEP! DONE! (Had to get the Hobby Lobby logo off of there).

Thanks... The Bum

Saddlebum

Hey Bear;

Did you cut the servo tray in half? From your pic (above) it looks like there are only two servo slots whereas my ARF has a 4 slot servo tray.

Is that just the angle of the photo hiding the "back" two servo slots?

I ask because I'm about to put in the 1/8" ply floor for the battery(s) and you mention your's goes from the front of the servo tray to just behind the firewall.

My ARF has a bulkhead just aft of the windshield. Did you build your battery floor to go through the hole in that bulkhead?

Sorry to be pestering you for so much information but you have solved the CG question and I'd like to learn from your experience if you don't mind.

Thanks... The Bum

cliffh

Keep in mind that a 16" prop is probably too large a diameter for a Telemaster. I fly with a 14x10 and clip the grass a little sometimes. I fly off an actual grass runway near my house and have no control over the height of the grass which tends to be around 4".

At any rate, watch the ground clearance.

Cliff

cliffh

Bear may have done it differently, but I put my battery tray on that "spar" or whatever you want to call it, that goes across that bulkhead. The front was mounted on top of a piece of 3/4" triangle stock glued to the rear of the firewall. I use velcro to hold the battery in place. Nice thing about the Telemaster is all that ROOM.

ESC went under the motor mount in front of the firewall for cooling. Fits perfectly.

Cliff

Saddlebum

Yeah, that sounds right. The battery under the cowl lid gives approximate CG as I understand it, right?

Thanks... The Bum

cliffh

Yep, mine worked out perfect. It makes sense since the original design used that space for the fuel tank.

Cliff

Saddlebum

OK!

It pays to look at all the wood in the box. Turned out there was a precut battery tray included. The instructions callit the "fuel tank floor" but it seems to work as a battery mount.

(See... even a blind squirrel can find an acorn!)

BEAR-AvHistory

Its a 4 slot tray & I am using the front slots to move the servos forward to help balance the plane.

Because I was adding a section to the, bulkhead you show in your picture, to create the slot for the wing mount I cut the lower cross piece out of it but left in the angle sections at the bottom. Then matched the square pieces already on the cockpit floor with a few pieces running crosswise to provide a base for the floor. I notched the floor where it ran through the bulkhead & built up a few more square sections to support the end of the floor in front of the former.

Finally, I left enough room between the new floor & the firewall to put a high voltage UBEC below the level of the battery to make it easier to get in & out as well as mount an on/off switch.

EDIT: My goal in placing the battery was to have it as low in the plane as possible for stability. The higher you are carrying you weight the less stable the plane is.

During WWII in order to get the P-51 Mustang to Berlin & back they added an 85gal "ferry tank" up behind the pilots seat. This made the plane very unstable & really deadly to its own pilot when ACM maneuvering. So what they did was take off on the mains, switch to the ferry tank to burn it off, then switch to the drop tanks till they were empty or the Germans showed up. The rest of the mission & RTB was flown on the main tanks.

Saddlebum

Hi Fellas... I just figured out I have my battery too far forward.

I built a tray for it in front of the windshield because that looked like an easy place to load and unload it... but, the CG is way off.

It really needs to be more under the wing to balance correctly, that looks like it means the wing has to be removed to replace the (motor) battery.

Do you have to remove your wing to get at your battery or have you figured out some clever way to get it back under the wing from the forward hatch?

Thanks... The Bum

kyleservicetech

Nice thing about those A123 2300 Milliampere hour cells. They are heavier, have lower voltage output, but do have zero fire hazard. So, they can be semi-permanently installed, and charged in the airplane. And, every so often, balance them when the wing is off.

From what I understand, the various Cellpro chargers do bring each cell up to the required 3.6 volts DC at full charge. (I've found that those plug in cell balancers that discharge to the same voltage don't work well with the A123 cells. Their voltage discharge curve is just to flat.)

cliffh

On my Telemaster, I put the battery right up front in front of the windshield. I did have to add 1 ounce of weight right at the tail wheel to get the cg correct though. Not a big deal on a 10.5 lb airplane. Guess each plane is just a little different.

I use a 4S 5,000 mAh lipo.

Cliff

Saddlebum

That's where I'd like to put my 5S 5,000.

Right now there are floats on it and I'm sure that moves the CG forward. Many guys put lead on the rear of their floats to keep the CG constant.

I'll pull the floats and reinstall the wheels to see if that makes a difference. But I'd still like to know if (other than Cliff) anyone else has their flight battery installed in front of the windshield?

...The Bum

BEAR-AvHistory

The front of a 5Sxxxx battery is just even with the rear of the hatch at the balance point. I use a full pad of velcro on the battery & tray.

The battery loads & unloads through the hatch.

Saddlebum

Sounds good. I'm using ACE hardware Velcro and it's so aggressive, I doubt I'd be able to "drag" the battery forward.

Are you using something a bit less aggressive?

Thanks... The Bum