Planning e-conversion for 33% extra

[whidbey1]

We were talking bout electrics at the field yesterday, people said this place has good deals and customer service is outstanding.
http://www.rchotdeals.com/

Good Luck

Bill

[Kiwi]

JBM,

I have the HXT 80-85 setup going into a 30% Pilot RC extra. Its taking longer than I planned due to some eccentric qualities I have about doing things different but here is a brief explanation.

The motor I have tested and it works fine. I am using a 100 amp Turnigy ESC from Hobby City. Appears to be OK in the static tests. But the motor has a design error and that is what causes the bearings to fail.

If you have access to someone with a lathe all you need to do is make a thin walled sleeve 35mm long that goes between the two bearings. That way when you yank on the prop nut you not crush the bearing races. They are made for rotating loads, not side thrust thus the failure issue.

I purchased bearings from VXB with ceramic balls. These and the bearing spacer will make this motor last a life time.

The ESC I feel is a tad on the light side and I would like to have something with a bit more reserve. 120 to 150 amp would be ideal.

Prop I have chosen is a 24 x 12 E. But I purchased one of everything from 15 inches up last week to have props to play with. Again Hobby City products.

Battery packs I will go with 12S x 8000 Zippy as it looks like I can get two rounds of sportman in with that setup and still make it home.

I also purchased an Emcotec in line switch but you can do the same with either a powerpole switch or a Deans plug jumper switch as well.

I should have everything here at the end of next week so it would be good to compare notes as you go.

[Mike Anderson]

	Quote: Originally Posted by jbm
	Your prop sizes are smaller than I was expecting; maybe I'm thinking wrong on that front... I assume you went with the A60 18L setup for the Suk then? How does the real world compare to the calculations? CG might be harder to attain with such a light motor I guess. I'm also surprised how well the cheap HXT motor does on your calculations. Has anyone had experience with the EMP branded motor that looks to be very similar to it?

Just a couple of clarifications.

1. I have not personally built or flown any large 10 or 12 cell planes yet.
2. Those calcs are my own from 1st principles based on published motor constants
3. I assume a Prop power factor mor in line with a typical Mejzlik in that size range.
4. The prop is sized to absorb the calculated full throttle static power, which will never be acheived in flight, so a one inch larger prop would probably be just fine in actual in-flight at partial throttle settings. (Hmmm, just got an idea for another modification to my XLS....)

Side note: My gas-engined H9 Yak 54 is giving me so much grief right now, I'm starting to seriously think about electrifying it. (The airframe actually shook apart last week!) But I would have to buy a gas engined generator to make it all work. . . . .

[jbm]

Appreciate that Mike thank you

Kiwi, having a good friend who owns a machine shop I'm not averse at all to some modification like you suggest. On that subject, I wonder if I could avoid a number of issues with the HXT / EMP motor by using it in the traditional outrunner 'back to front' configuration. I could have my friend turn up a prop adapter for the plain end of the shaft, perhaps even with a typical 4 or 6 bolt gas configuration if he's feeling generous. That way the torque to pinch up the prop is not affecting the bearings, and the pull of the prop in use is not trying to separate the two parts of the motor. What do you think? Obviously I'd need then to mount the motor in a cage type mount, but that kind of fabrication is no sweat at all.

[Kiwi]

John,

I just had a look at your profile and had to pick myself up off the floor from the laughing. Looks like many of us have been down the same lane mate.

Anyway the HXT motor. If you reverse it then you get away from all the issues but at the same time if you fit the spacer (very simple to make) you get the same result and the ease of installation without adding weight.

Now I have made a new shaft for mine and all the shaft will do is hold the motor together. The prop will be mounted AKA DA 50 with the same bolt hole spacing etc. The shaft will also be much smaller as at present it is 12mm and that is a hole in the prop that means your stuffed if you want to use it someplace else. I think the DA50 hub is 10mm or 3/8. The intention is to have that protruding shaft plain. The nut to hold the motor together will likely be 10mm as well and that will be buried in the prop hub. I am sure you get the idea. The end of the new shaft will be drilled and tapped for a spinner bolt if I ever need one.

I have the first part of the shaft ready today so may put up a photo to explain more clearly what my intention is.

There have been reports of magnets popping out on the HXT as well but mine are fully bonded and the glue has formed a good bead all the way round each magnet. I also used an iron bar to stick onto each magnet and try to lift them off the shell. None of them moved at all.

The bearing numbers if your interested are 6801RS and 6901RS. Easy to buy good quality at the local bearing supply shop.

People that have written to me about the HXT say that an E prop is absolutely critical. The props for gas motors dont work, its that simple to say.

[MarkF]

LBM, I think you should look at a Neu 1527 1.5Y 6.7 gearbox. This setup will give you the power your looking for and will run on 12s 1P castle 110 controller and apc 27 x 13 or 26 x 15 electric prop. This has been used on many 33 % planes with great success.

Mark

[Kiwi]

OK

Here is the super simple fix to the bearing problems with the large Turnigy outrunners.

This sleeve is aluminium and .05mm longer than the bore in the field winding casing. What this does is space the bearings apart so when you wrench on that prop nut you have a solid shaft from the rear circlip to the nut.

This way the bearings take no crushing loads from the nut torque.

[jbm]

Awesome help, thanks Kiwi I'm always willing to give budget components a go- as long as you've got your eyes open and are careful its ok, and it has panned out well for me in the past. ( In fact my first lovely DA-85 died the prop hub death not long after I bought it... any piece of gear can fail- the difference being that with a premium product you send it in for service, whereas with something lesser you've just got to expect to deal with it yourself )

[Kiwi]

Very true mate.

I have another thread going here that I will put a link to as I have also made a new shaft for this motor that ups the anti even further I think.

http://www.flyinggiants.com/forums/f...-electric.html

[jbm]

Resurrecting this old thread - I finally kicked my friend's ass to get a motor mount made, so now the 33% extra is alive Cheap hobbycity components used, but the motor has been stripped and reassembled with a couple of mods.

(Side note: On another motor of the same type it arrived with loose screws holding the can to the shaft, and the circlip holding the shaft in not seated. Neither problem was very noticeable to the naked eye, and would have resulted in failure in no time at all. Combine that with a design that won't let you wrench on the standard prop nut very hard, and I think 90% of the reports of failure can be covered- poor factory assembly and one design flaw. Fix the flaw and check it over with a careful eye and you're home free.)

I'll be re-maidening the old girl at the weekend, and ground running at the club field tonight to check rpm and current draw. Everything runs smooth and clean in the workshop, but full throttle was in danger of rearranging my tools LOL

The spec is:

EMP 80-100 130kv motor (basically a slightly evolved version of the good old turnigy magnet dropper / bearing wrecker)
Custom DA50 style prop hub, doubled up grub screws for shaft to can. Custom mount to match DA-85 pattern for convenience.
120A K force controller
26 x 12 wood prop
12s 6500 or 12s 5000 packs

I'll keep you all posted.

[jbm]

On freshly charged packs, after the 10 seconds of wide open throttle it settles to 90A and 44V on the 26x12 - just under 4kw input, which should be OK for starters. On the ground it feels like it pulls every bit as hard as it needs to

I've room to prop it up a bit further if I feel like it needs it. Flight report at the weekend

[jclaude]

Hi JBM,

Could you post some pictures of your home made prop hub?
I waiting for your flight report.

Regards,

JClaude

[jbm]

I'll take some pics tomorrow - I'm expecting a larger prop to arrive so I'll be taking things apart

I've only flown it on a 26x10 so far, as I didn't notice that my 26x12 was drilled for a different spinner... the 26x10 is a bit lacking in power, drawing only 75 amps, but the plane flies OK for pattern on it. I'll test a 28x12 - hoping it'll draw about 110 amps.

The sound of the plane in the air is lovely- its as loud on a down line as on the way up LOL

[gdryer]

In case you missed this in my Sukhoi thread. Here are the numbers for my ESC test on basically the same motor.

HXT 80-100-130 motor
Xoar 27x12 propeller
4- 6S Zippy 4000 (20C) 12S-2P
Ambient Temperature 35C at sea level

[jbm]

Well my ESC died on the ground... a shame but I think there was an inherent problem of some sort, as I was monitoring the voltage and current closely on running up a hotter motor for the first time. (180kv instead of 130kv).

At 42v and 70 amps the magic smoke came out of the K Force 120A controller... closely followed by the magic bloody great flames - fortunately everything survived, except the paint on my cowl which bubbled from the momentary heat!

I've been happy with the HXT motor, but having seen the new version Hobbycity are selling I'm going to be much more comfortable throwing the plane around. It looks the same, but really isn't. Huge great rear bearing, no more reliance on a tiny retaining circlip and even a standard gas style prop adapter to get away from torquing against the bearings when fitting your prop. The windings are nice and tight and well done too, where some of the old ones were very lazily produced.

HC are now also selling an ESC that truly opens up the potential of the motor: 200 A HV esc It seems to come from a respectable manufacturer too.

I might yet get close to the crazy vertical that I get with my 27% / Hacker A60 setup.