Any dual shaft motors?

[glassdoctor]

As the title reads... does anyone know of a good BL with output shafts on both ends? Something similar to a Hacker b50 or Lehner 1930...

Thanks

[Mr. Constructor]

it isn´t a problem to order all hackers WITH a shaft coming out at the end, it might take some time for you in the US, in germany it is around 2 weeks !!

and there are several LRK´s out there that might be available as a 2 shaft version, i think you thought of a motor wich could be installed as a 3. gear in these 8th buggys (instead this gear!!) look at this one, the front is propelled by a long titanium shaft (dog bone) that is mounted via a normal drivepin on the front shaft of the Motor (in the big middle case) then the aft shaft propells the aft drivetrain via a direct link adapter (from 5mm shaft to 8mm shaft on the trannys gearing)
It was a Kanai Buggy conversion, the buggy is fully ready now, this pic shows it during installation.

[glassdoctor]

Yep :) that's what I was thinking about doing... on an 1/8 and on my Emaxx too. I hate that Emaxx tranny.

[Rotary Rocket]

The problem I see with connecting your motor directly to the front and rear diffs is the RPM!

If you eliminate the tranny then you are losing a lot of mechanical torque. Your motor will be working VERY hard. It will probably result in frequent thermaling followed by smoked motor/controller.

Maybe if you get a really high torque (large can, high turns) motor it might be possible.

[glassdoctor]

Yes, you have to account for the lack of the pinion/spur ratio. But that's just a matter of finding the proper motor wind. You wouldn't use the same motor as with a 3:1 tranny for example.

There are plenty of very powerful torque monsters with low k/v specs.

Let's say the tire diameter is 4.5" and the diffs are 2.5:1 ratio.

A Hacker B50 18XL on 14.8 Lipos calculates a max of 5192 rpm at the wheels which is 69 mph.

Hacker B50 21XL calculates max 59mph by the same #'s.

I don't know what the actual mph's would be... maybe 80-85% of the calculated #'s? Depends on the weight and watts etc...

As a comparison, the same calculations for my C50 and Emaxx stock tranny 20/66 gear and 6" dia tires on 14.8 lipos gets these #'s... seems accurate:

1st gear: 30 mph
2nd gear: 49 mph

Knock off @15% for real speeds and that's 42 mph... probably about right.

Any reason we can't just pick a motor based on k/v assuming the watts are sufficient? Won't the XL or L series be a good choice?

In theory with these #'s, the B50 21XL would do @ 50 mph actual top speed. That sounds great... even if it was 20% drop that's 40+ mph, just like a good nitro setup. Pefect for racing, I would think.

BTW, I didn't actually check the dia. of tires and diff. ratios... just guessed. But you could plug in the exact figures for your buggy and run the #'s.

(K/V x Volts) divided by final gear ratio to get the rpms of the axle/wheel. (only diffs @ 2.5:1)

Then find the rollout, circumference of the tire... in feet. (4.5" dia x 3.14= 14.1" = 1.17')

Multiply the axle rpm X 1.17 = feet per minute.

Take that X .oo1136 to convert to mph.

((k/v x volts)/2.5) x (1.17 x .001136)

[glassdoctor]

btw, i really like that buggy/ motor mount. I was thinking of mounting it more in the center and using universals, but I like they way that looks...

[Signats]

Not to rain on your parade or anything, but have you considered the forces that that are generated when a 12lb vehicle is landing from a jump or, going through the whoops, or tumbling down the track in a crash?

The uneven loads applied to each end of the motor shaft would be huge as one end of the vehicle loads and unloads the tires.

Nitro buggies have a clutch, electrics have slippers, how do you plan on dissapating the spike loads? by twisting the motor shaft?

Good Luck!

[glassdoctor]

I wouldn't be running on pavement :)

Really, on most dirt tracks, the tires are always breaking loose, so I don't think it's a big deal. Worst thing would be bent driveshafts or broken diffs/cups.

You are right though, and that's the first thing that came to mind for me too.

You would have to use proper driving techniques to help prevent damage ... which means you shouldn't land WOT anyway. It would not be a good setup for bashers...

I have looked at some rubber flex couplers that may help absorb shock to the drivetrain, both from pure horsepower and traction, and from head on impact with a barrier which tends to tweat chassis and center driveshafts. Don't ask how I know about that one :o

The goal is a no-gear drivetrain... lightweight, low c.g., and efficient... there may have to be some tweaks to get it to work well, we'll see hopefully.

[glassdoctor]

Of course, there is also the option of just using this...

http://www2.towerhobbies.com/cgi-bin/wti0001p?&I=LXCXB2&P=7

you would have some gear reduction and also a slipper clutch... no problems then. :cool:

But right now I'm still considering the possibilities of no gears at all (except diffs of course)

[Signats]

Really, on most dirt tracks, the tires are always breaking loose, so I don't think it's a big deal. Worst thing would be bent driveshafts or broken diffs/cups.


I have driven my xx4 with the slipper removed, and without something to absorb the spike loads you will definately find out what the weakest link in your driveline is........ and even parts like dogbones, and drive cups don't break they are not really designed for that kind of loading and will wear out at a much, much faster rate.


You would have to use proper driving techniques to help prevent damage ... which means you shouldn't land WOT anyway.

If you intend to race it, then your buggy will need to be able to land repeatedly with full on power at some time or other (obstical dependant), anyway on a dirt track a vehicle can become airborn any time and on any part of the track, if you drive on dirt rc tracks you know accidents not only can they will happen and when they do happen buggies will fly....

Again, good luck with your project, just trying to provide you with some things to think about as you work out the details......

[glassdoctor]

No problem, I know what you mean about the slipper... I have raced off road for 15 yrs... :cool:

Like I said your're probly right, but only one way to find out, right? ;)

[Mr. Constructor]

Don´t mix that up, the Buggy i built has a special Motor, it IS NOT a Hacker, the torque will be too less (even with a low wind C50 XL version) I generate the extra torque electrically by using an 10 pole LRK Motor, the rotor is rotating outside around the motor in this version jet give it around 5-7 times the torque a Hacker will do !!
(see pic, then you know why i had to built this Motor housing, the can is rotating, the dirt has NOT to come inside !!)

And as for strength,the full drivetrain was made out of thick Titanium and the Motor itself is made out of it in the Main Parts too !!

So this part is also covered, the Motor uses only one Shaft to the front, as it is easier to propell the back shaft via a direkt titanium adapter (all round or plate design parts are out of this material) and then ONLY the front one with a self made elongation (also Ti is used) on the front end.

So this system really IS reliable, but until you do not use these Motors (watch www.torcman.de Then the english version and the 350 series Motor) with some well choosen Hard Parts (has NOT to be the full car out of Ti, but some drivetrain parts are helpfull)

overthink it, as the calculation of the needed Power and rpm isn´t that easy!!

(it was my 2nd project with these LRK Motors, they really are powerful, but not easy to use as for their electric and mechanic (the rotating endbell) needs, but IF it worked, it worked really great and the efficency is really a blast!!)

[glassdoctor]

Funny that you mention these motors, that's one I was looking at. One of the guys in another forum gave me a link a few days ago. I was thinking about the 350-28 or even a 430 series. You have used a 350 ? I never thought that someone might have already used one of these in a car! :eek:

Cool... and they are relatively inexpensive, and you can easily customize the shaft and mounting options. How well did it perform?

I started looking at these after reading about homebuilt cdrom motors. I want to get parts to wind some custom outrunners... maybe for a mini or my 1/10 pan car. :D We'll see...


Thanks again

[Mr. Constructor]

It really performs very well, the car is awesome in handling, power isn´t that brutal than the other 2 pole Motors i have in various other cars, over all a really powerful thing, but there is always something to make it better, next time i will use the normal 2 pole hackers again, then go with 3 diffs in a new way (3rd diff has to go back near by the back tranny (same propelling than this car, but with a diff in the middle and a 2 pole Hacker driving the whole thing, but the space comes very limited in this version, but maybe i´ll find some solutions to get all the electronics under this hood (maybe a Mugen MBX 5 or a Ofna/GM/Graupner/GS Speed 9.5 ?? Haven´t decided yet)

As for your thinking:

The Motors where only able to run very efficently with 3 esc´s:
1.Hacker Master Comp. (better Amp stability, but BEC needs to be replaced by a Battery, will otherwise break down and Car comes Uncontrolable)
2.Schulze U force 75, should be a great thing, but costly, otherwise waterprooved and one of the best out there
3. the Kontronik JAZZ Series (watch www.Kontronik.com for details, the beat is simlar to the JAZZ (JAZZ has some new Lipo Features)

Anyone of these esc´s will handle the LRK AND !! the prop. Brake needed for a Car (or do you wanna brake via Servo and mechanically adding extra weight ??

The only cars i do so are some of my 5th scalers and my new project my Mad Force in BL Version (wich should be run by a Hacker B50L in 7 turns and then 12 cells a Carbon Chassis, titanium parts in the drivetrain, most parts are clear for now, just have to built a few and mount the thing together.

In this heavy truck you really ned the mech. brake, the electronical might be overstressed (but it was not in my 6th buggy, but this is another story . .;-) )

[glassdoctor]

MrConstructor
thanks fro the info...

I like what I have seen about the Jazz controllers, but I did not think there was one to handle the high current motors. Is there a step above the Jazz 60? I was looking for at least a 90 amp rating for any future Emaxx type application.

For 1/10 scale cars I definitely am looking more at the Kontronik stuff.

Too bad they are hard to find over here... if more shops would import them, they would become more popular.

[Mr. Constructor]

As far as i saw on the german page ther is a JAZZ 80-6-18 WITH BEC, this one is cutted of at 100A (and several other things, have you tried to download a manual first ??)
Price is not listed here in Hamburg, but should be around 210-230 Euro !!
(shall i ask it for you ??)

so this one might be ideal for everything in cars (maybe not 5th or 6th but the rest of it !!)

do you have some adresses where you might get some Stuff in the US ??
(Nitroboy24 is searching for them, maybe i could give him some adresses??)

[glassdoctor]

This is the closing thing I have found so far but it looks good...

http://www.icare-rc.com/motor-controls.htm in Canada

They list a bunch of Kontronik stuff... and they have the Jazz 80. $299

BTW, for a 1/10 buggy and a milder motor which would be better, a Jazz 40 or a Smile 40? they have similar specs, but the smile is cheaper and smaller...

[Mr. Constructor]

If you wanna choose the Smile series, be careful to get the latest software version, then ONLY then the lipo cut of mode will be integrated (and some other programmes for some other modells are missing compared to the JAZZ)

Otherwiese the Smile is at least not that powerful, it could only take 40 A and 50 A peak (there are more powerful versions available as a JAZZ, and the software is def. the best and newest one out there, if the difference isn´t that big, i would take the 55-6-18 JAZZ With BEC then you´ll have enough for almost every CAr application you could think of (even 8th conversions are possible (but with extra heatsink)

These are the Major differences between these series (the JAZZ also has more freuquencies to choose from and has a PC interface (sep. adaptor cable is neccessary) so take care of the Software status, you could update them regularly, but they will be send in to the factory i think, so get the JAZZ line, to be on the safer side !!
(my try in that Dyna Storm will def. be the 55-6-18 BEC JAZZ and a Twist Motor)

greetings from Germany

[Popop]

Hi Mr Constructor

Electronicmodel manager can also sell you one of his motors with twice shaft
I asked for him when I developped my Brushless 1:8 touring back in the year 2000 ...
The important cogging at low rpm along with the lack of speedway made me turn my car to an everyday sport machine with a 700 Neo motor ...

All that said, small tourers like TC3, TB, etc. would be great challengers for speed record events in that kiss (keep it simple stupid) configuration ...

Just a question to Constructor :
Do you think that watercooling seriously a B/L will allow you to isolate it from the airflow (thus the dust) ? Thanks !

[Mr. Constructor]

Hmm good question, i was thinking of a watercooled one too, watch these small micro PC cases, they use a heat pipe system to transfer the heat from the CPU (around 100° celsius, and around 100W (modern 2-3Ghz systems) so this might be usable for cars too, but the general question is the heat itself will be only transferred from the motor to another point, its always there !!
one of my favorite thoughts include this:

a aluminium plate (as the basic chassis plate) made out of around 5-6mm thick material (or you might get a Space frame Aluplate (2 plates, there are several rooms between for the water, but those are only available for Airbus oder several airplane builders and are around 10mm at the smallest)
the have the material cut away (in small 3mm wide and around 2mm depth) all around the plate, like a spiral, coming from the middle and then going to the outside (input and output) then connect a small gas nipple, and get a 1mm plate (alu or carbon) and glue it on the other one, in this way you could use the whole chassis (underflowing air is used) to cool the water (wich is only transporting the heat from the motor) in this case the weight is down to the maxx and the effect should be great !!!

Yes the full energy can be cooled away, but this might lead to a very high cooling area (like i told before, this might be the best way to get the greatest area and using a water cooled unit (with a small pump running the water through it.

What where your thoughts ??

[glassdoctor]

What about a sealed air cooled system with a high flow air filter? :)

[Mr. Constructor]

I know popop, if he´s thinking in that direction, he´s planning on something, maybe the motor should be totally enclosed to get the results he wants, so he cannot use a vers good filter for the air, normally a Air cooling doesn´t provide that transporting power (cannot transport that much heat than a water cooled will) so the best solution might be a water cooled one, maybe not filled with water, maybe some other fluids wich even cool better than normal water !!
(but the system needs to be integrated in the whole car design, so it might not be easy to construct, if you have a CAD Programm, that might not be a problem then . . . (but it will take several hours to construct it, i know that, my parts are constructed on a CAD programm, it´s not that easy to construct then a full new design !!)

[Popop]

I also considered PC motherboard cooling systems but they seem too sophisticated for me
We actually doesn't need any pump once the convector is place upside
I also think the lightest way would be to use glycol and sheetmetal convector in order to optimize Joules dissipation for a given weight
You even can fill in the convector with cold glycol just before you start running
-> Anyway, such a system cannot work with extra Wh onboard ... It will be ok only for a limited energy to dissipate thus a limited runtime ... Or you'll probably have to equip the circuit with a Pelletier system ;o)

concerning the rotary B/L (lrk design), www.electronicmodel.com did a great work on optimizing the concept ... It results in their Twister29 astonishing brushless for 125€ only

[Mr. Constructor]

These peltier elements are way good for PC Cpu´s, but they draw a lot amp, so the use in a car will not be any good thing !!

Maybe you should try to get the Motor cooling by enough cooling space (meaning the motor mount has to be large and aluminium and maybe drilled or machined out to increase the area.

This helped a lot in my 6th buggy, so i do not need any sep. fans or something and the Motor and Motormount are totally under the Body, so Airflow isn´t that big, but the motor was around 40 ° Celsius after a 12-14min run with very high power driving, so nothing in the red alert area !!