Limitless LibertyMkiii's crazy belt drive car project

[LibertyMKiii]

Remember, wire length is as important as wire size. The filament portion of electrical fuses are thin as hair, yet carry the full current of a circuit up to their rating because the section is very short in length. On the other hand, damn those wires are skinny! I'd feel a lot better seeing some copper ingots bridging the connection.

This motor is only rated at 120a. In this situation I think that may hold more true than some others.
I know a guy running a TP5660 that is rated for 277 amps and has made 30+ runs over 150 mph! His data logs show over 500 amps on it!!!

I just cannot imagine this specific motor's wire being able to withstand 4x its rating if I went 500+ amps with it.

 

[Monster Dork]

Is 120 A a continuous rating? How long do those transient spikes last? One thing is for sure, the smaller the conductor, the more heat you get. If the internal windings are thin, it'll be a very hot motor. Of course, the diameter of the wire has a huge impact on the motor's performance properties, so there may not be much you can do there. You are attempting a speed record in earnest, maybe it's worth a phone call to TP to chat with a product engineer about your unique needs. Since you have done a great job of documenting the process online and it isn't your first rodeo, you might be a good candidate for sponsorship.

 

[LibertyMKiii]

Is 120 A a continuous rating? How long do those transient spikes last? One thing is for sure, the smaller the conductor, the more heat you get. If the internal windings are thin, it'll be a very hot motor. Of course, the diameter of the wire has a huge impact on the motor's performance properties, so there may not be much you can do there. You are attempting a speed record in earnest, maybe it's worth a phone call to TP to chat with a product engineer about your unique needs. Since you have done a great job of documenting the process online and it isn't your first rodeo, you might be a good candidate for sponsorship.

TP Power in my experience has been very difficult to reach and work with. I don't foresee any sponsor deal occurring, but it never hurts to ask I suppose. TP Power's ratings are always peak ratings. I believe they indicate 10 seconds or less at peak power (which would be fine for speed runs). As noted I have seen many people push them well beyond that rated value, but only around 2x.

 

[rotauq]

Motor specs are on peak W and an advised max voltage (basically max rpm/ KV), of which the last is certainly related to the wire diameter. Rated at 120A it's meant to get max(optimal) voltage of 75V.

It will certainly deliver 9kW at 33.6V @267A, but to push it to 13.5kW under load will make it go hot/burn out indeed. (unless you pre-cool it with Nox/dry ice)

I think it's wise indeed to change the motor to a thicker wired one. My guess is that resistance of the motor on the TP datasheets gives a rough estimation of the cable thickness. Sad part is that a higher kv would screw up your gearing design and the limitation you've set by the belt going under/over the motor.

 

[LibertyMKiii]

Motor specs are on peak W and an advised max voltage (basically max rpm/ KV), of which the last is certainly related to the wire diameter. Rated at 120A it's meant to get max(optimal) voltage of 75V.

It will certainly deliver 9kW at 33.6V @267A, but to push it to 13.5kW under load will make it go hot/burn out indeed. (unless you pre-cool it with Nox/dry ice)

I think it's wise indeed to change the motor to a thicker wired one. My guess is that resistance of the motor on the TP datasheets gives a rough estimation of the cable thickness. Sad part is that a higher kv would screw up your gearing design and the limitation you've set by the belt going under/over the motor.

Exactly, I was playing the game with total wattage handling of the motor.... Move the volts down and amps up, but had not realized the wire size would change so much.

It looks like you are correct on the resistance at certain KV the wire makes 4 drastic changes in size:

 

[Grimbles]

Had been behind on this, but just caught up. Keep it up @LibertyMKiii - along with pretty much everyone else here, rooting for you mate

 

[phildogg]

Project is coming along nicely. I really want to see it running.

 

[LibertyMKiii]

Had been behind on this, but just caught up. Keep it up @LibertyMKiii - along with pretty much everyone else here, rooting for you mate

Thanks man, really appreciate your contribution towards the project!!!

Project is coming along nicely. I really want to see it running.

Thanks Phillip, you were my inspiration to get into this part of the hobby. You always have been and always will be the king of speed.

 

[LibertyMKiii]

Update from this weekend. The Noble NB4 radio showed up finally.
I was very impressed with the packaging and the overall look and feel of everything. The radio itself is amazing.... I love the menu, vibration feedback, and audio. I have already connected it to my PC and updated to the latest firmware. Up next I'll have to add the signal booster. I was a bit surprised to find out the guts of the radio actually live in the board for the screen. The radio feels solid and very well made. My only complaint would be the out of box range and screen visibility is bad in daylight.

The Radio came with 2 RX and I had purchased the FTr10 earlier, before the radio came in.

The belts and timing pulleys gears came in Friday also. After reading on Gates website I had decided on the GT2 series. I chose the 3mm pitch and 9mm wide belt. The belts contain fiberglass chords for extra strength. Once you get over a certain size the pulleys no longer have the side flanges that guide the belt straight. This wont be a problem because I plan on using a small tensioner/guide that does have those side flanges..
I went with the fair-lock design pulleys that do not use a set screw. They are supposed to hold very well. If I have any issues I can always pin them.
I spun the rear tires and the belt for the rear stays on track well. I am not able to test the front yet. Speaking of the front you will noticed it has teeth on both sides. This was my only option in the belt size I needed, unless I swapped over to HTD gears and belts.

As mentioned before the pulleys for the belt drive are all 50T creating a 1:1 ratio for what we would normally call the differential ring and pinion. In order to gear down enough I have decided on mod 1.5 gears on the spur and pinion. This was the only option other than belt drive, which I wanted to avoid on the motor connection. I don't love the loud sound of mod 1.5, but other than that they should do the job perfectly.
Using the mod 1.5 should allow me ranges 2.5 FD to 1.88 FD. (pictured are mod 1 gears)

 

[claytonbakerjr]

Looking great...
So not being too knowledgeable about Land Radios please forgive my ignorance with the questions.
I know that you have the RC6GS and you mentioned it had great distance with your Limit, so what
was the incentive for the NB4? Even better distance? Different options?
Another item I see you mention (as well as others) is a Signal Booster.
Again maybe ignorance/lack of knowledge but if the RC6GS gives someone the distance
almost beyond eyesight (if not more) why a signal booster?
Sorry just trying to wrap my head around these items before I get myself in trouble

 

[rotauq]

Looking great...
So not being too knowledgeable about Land Radios please forgive my ignorance with the questions.
I know that you have the RC6GS and you mentioned it had great distance with your Limit, so what
was the incentive for the NB4? Even better distance? Different options?
Another item I see you mention (as well as others) is a Signal Booster.
Again maybe ignorance/lack of knowledge but if the RC6GS gives someone the distance
almost beyond eyesight (if not more) why a signal booster?
Sorry just trying to wrap my head around these items before I get myself in trouble

https://www.arrmaforum.com/threads/radio-for-speedruns-and-noble-nb4-discussions.33883/



I do wonder if accelerating and braking does on the belt, one side will tension the other will 'flabber' lose. You don't want it to grind on the motor. A tensioner is definitely help, but not entirely. Then again with your overpowered chain driven quad you've probably dealt with this before.

 

[claytonbakerjr]

https://www.arrmaforum.com/threads/radio-for-speedruns-and-noble-nb4-discussions.33883/



I do wonder if accelerating and braking does on the belt, one side will tension the other will 'flabber' lose. You don't want it to grind on the motor. A tensioner is definitely help, but not entirely. Then again with your overpowered chain driven quad you've probably dealt with this before.

Thanks @rotauq

 

[LibertyMKiii]

Looking great...
So not being too knowledgeable about Land Radios please forgive my ignorance with the questions.
I know that you have the RC6GS and you mentioned it had great distance with your Limit, so what
was the incentive for the NB4? Even better distance? Different options?
Another item I see you mention (as well as others) is a Signal Booster.
Again maybe ignorance/lack of knowledge but if the RC6GS gives someone the distance
almost beyond eyesight (if not more) why a signal booster?
Sorry just trying to wrap my head around these items before I get myself in trouble

I sold just about everything RC I owned to fund this project and start over with different equipment.
I was having some response latency with the RC6GS when beyond 900 ft. I have heard some mention the same results, while others say there is no issue, so maybe it is just my eyes? (or I have un-reasonable expectations?)

Ultimately I decided I would want to run a signal booster no matter what radio I was using as extra insurance given the speeds and distances this car will need to go. I believe the strong signal output will help with all aspects of the radio equipment. I also wanted to use a throttle control like the perfect pass, but the Noble NB4 has a better version of it built in. It is far more accurate/controlled than a potentiometer setup like the perfect pass has.

I know that some say an controlled throttle input is not driving the car yourself. I get it, but don't care what "they" think. For me this is a task of engineering. Consistent data and controls help in making next gearing/setup decisions. I'll be the first to say that I am not the most skilled driver, so I can use the help in that area from the transmitter. On that subject I don't plan to run a gyro at this time.

 

[jondilly1974]

I sold just about everything RC I owned to fund this project and start over with different equipment.
I was having some response latency with the RC6GS when beyond 900 ft. I have heard some mention the same results, while others say there is no issue, so maybe it is just my eyes? (or I have un-reasonable expectations?)

Ultimately I decided I would want to run a signal booster no matter what radio I was using as extra insurance given the speeds and distances this car will need to go. I believe the strong signal output will help with all aspects of the radio equipment. I also wanted to use a throttle control like the perfect pass, but the Noble NB4 has a better version of it built in. It is far more accurate/controlled than a potentiometer setup like the perfect pass has.

I know that some say an controlled throttle input is not driving the car yourself. I get it, but don't care what "they" think. For me this is a task of engineering. Consistent data and controls help in making next gearing/setup decisions. I'll be the first to say that I am not the most skilled driver, so I can use the help in that area from the transmitter. On that subject I don't plan to run a gyro at this time.

My experiences with the CH Speed feature is hit or miss. If you get a “Signal lost” error at the starting line like I frequently do, the CH Speed feature gets ignored and you will get full throttle input to the ESC. What I have tried so far, and seems to be a workaround, is to wiggle the steering before using the throttle after getting that error to re-sync the connection. It seems to have worked so far. I am resisting boosting this radio as I wanted to use it for bashing too. If the booster becomes necessary, I will probably just buy a second TX and boost it and leave this unit as a bashing radio. I have quite the collection of radios right now and could probably find the second NB4 by selling them

 

[LibertyMKiii]

https://www.arrmaforum.com/threads/radio-for-speedruns-and-noble-nb4-discussions.33883/



I do wonder if accelerating and braking does on the belt, one side will tension the other will 'flabber' lose. You don't want it to grind on the motor. A tensioner is definitely help, but not entirely. Then again with your overpowered chain driven quad you've probably dealt with this before.

I just ordered a set of idler pulleys on Amazon and this should address those issues along with alignment. I think with those in place I should be fine, but only testing will tell. I still have concerns about the fairlock system holding also. I'll mark the timing pully and the shaft to determine if there is any slip. A few drag style runs should show the problems if they exist.

Grip on the belt was one of my big concerns. The big perks of using the 50t gears is that they have 27 teeth in mesh with the belt!

ATV/Motorcycle chains are a different animal as they can be significantly more loose and still "grip" well. On my first build using a 600cc GSXR motor I had a cheap Chinese chain break. I was lucky that it didn't take my leg off!!! The bad luck was that it knocked a hole in the engine block as it whipped over the transmission output gear. That was a great excuse to get the 750cc motor

My experiences with the CH Speed feature is hit or miss. If you get a “Signal lost” error at the starting line like I frequently do, the CH Speed feature gets ignored and you will get full throttle input to the ESC. What I have tried so far, and seems to be a workaround, is to wiggle the steering before using the throttle after getting that error to re-sync the connection. It seems to have worked so far. I am resisting boosting this radio as I wanted to use it for bashing too. If the booster becomes necessary, I will probably just buy a second TX and boost it and leave this unit as a bashing radio. I have quite the collection of radios right now and could probably find the second NB4 by selling them

It does have 2 signal outputs, maybe you can setup the booster to be easily removed and use the internal antenna for bashing?

 

[Monster Dork]

You can boost signal with a high-gain antenna, which is a compromise between coverage and power.

Or...

You can run an amp. The DALRC booster is easy to work with, and has a passthru mode. It looks like they are available again. Don't tell the FCC.
http://www.dalrcmodel.com/DALRC/plus/view.php?aid=179'
https://www.rcgroups.com/forums/showthread.php?2754867-DALRC-2-4G-8dBm-power-amplifier

Of course the best gains of all are had through mounting your antenna up high.

 

[rotauq]

I just ordered a set of idler pulleys on Amazon and this should address those issues along with alignment. I think with those in place I should be fine, but only testing will tell. I still have concerns about the fairlock system holding also. I'll mark the timing pully and the shaft to determine if there is any slip. A few drag style runs should show the problems if they exist.

Grip on the belt was one of my big concerns. The big perks of using the 50t gears is that they have 27 teeth in mesh with the belt!

ATV/Motorcycle chains are a different animal as they can be significantly more loose and still "grip" well. On my first build using a 600cc GSXR motor I had a cheap Chinese chain break. I was lucky that it didn't take my leg off!!! The bad luck was that it knocked a hole in the engine block as it whipped over the transmission output gear. That was a great excuse to get the 750cc motor

Some drag/launch test will tell indeed.

True a ATV chain is more prone do go lose. Still thinking about lifespan of tensioners of my lawnmower. Obviously that has a rough clutch and is kicked it in when there are already rpm's in play.
Good to here you didn't lose you leg, that would have been problematic

 

[LibertyMKiii]

Few updates.

Sold the TP4070 (780kv) over the weekend. Only took 2 days on eBay which was faster than expected.
Payout just occurred this morning and I ordered the same motor in a 1700kv wind. The motor is an "in stock" model so hopefully I don't have to wait as long this time.

Also working on my signal booster setup for the Noble NB4. I'll post a thread on how-to and link it here once that is done. Then I need to go out for some rang testing with my son's Slash monster truck (our only working RC right now)

Managed to catch a sinus infection over the past weekend so I have not felt up to finishing the front axle yet.
Mod 1.5 gears should be in by this weekend

 

[jondilly1974]

I just ordered a set of idler pulleys on Amazon and this should address those issues along with alignment. I think with those in place I should be fine, but only testing will tell. I still have concerns about the fairlock system holding also. I'll mark the timing pully and the shaft to determine if there is any slip. A few drag style runs should show the problems if they exist.

Grip on the belt was one of my big concerns. The big perks of using the 50t gears is that they have 27 teeth in mesh with the belt!

ATV/Motorcycle chains are a different animal as they can be significantly more loose and still "grip" well. On my first build using a 600cc GSXR motor I had a cheap Chinese chain break. I was lucky that it didn't take my leg off!!! The bad luck was that it knocked a hole in the engine block as it whipped over the transmission output gear. That was a great excuse to get the 750cc motor

It does have 2 signal outputs, maybe you can setup the booster to be easily removed and use the internal antenna for bashing?

Wow that would be amazing! I need to research this. Easier than a second radio.

 

[Doom!]

Excuses, excuses, this project should have been done months ago....time to get your priorities straight, your health, job and family should have no impact on this project!