Limitless Rot's 140+ mph Limitless GT build log

[LibertyMKiii]

Very excited to see what you can do!
I know time is limited before you go run but if you have any way to put some foam under the body to keep it from flexing I highly recommend it. Basically create a block between the car and the body where the body cannot cave in.

Good luck man

 

[rotauq]

Well, just returned from the airport. They were friendly and interested in what i was doing, I'll likely get access more often.
No PB this time, bummer. The weekend was quite chaotic so I couldnt prep like i would have wanted.

At my 6S 'how does it all feel'/calibration run I it seemed my signal booster stopped working. So my range was already limited.
And it was quite windy, and at an open space airport it's much more of a problem than i am used to. I had a hard time keeping it straight. The tarmac was ok, little wet and rounded in the middle which didn't help either.

Using the innerlane was a bad move, at the taxi turn it was rather bumpy, where it lost control and rolled. After that crash, 2 damaged BSR's and my front suspension acting up, chances for a PB were gone. I still explored some and found some better paths for the future.

 

[Edough13]

Well, just returned from the airport. They were friendly and interested in what i was doing, I'll likely get access more often.
No PB this time, bummer. The weekend was quite chaotic so I couldnt prep like i would have wanted.

At my 6S 'how does it all feel'/calibration run I it seemed my signal booster stopped working. So my range was already limited.
And it was quite windy, and at an open space airport it's much more of a problem than i am used to. I had a hard time keeping it straight. The tarmac was ok, little wet and rounded in the middle which didn't help either.

Using the innerlane was a bad move, at the taxi turn it was rather bumpy, where it lost control and rolled. After that crash, 2 damaged BSR's and my front suspension acting up, chances for a PB were gone. I still explored some and found some better paths for the future.


View attachment 173525

Man was hoping things would go a lot better for ya that's unfortunate. Sure it will take a couple trips out to get used to the new surface and pick a good lane so to speak. Hopefully next time out goes better

 

[Doom!]

@rotauq Nice looking spot! Hope you get it sorted out soon!

 

[Sandracer_NL]

Well, just returned from the airport. They were friendly and interested in what i was doing, I'll likely get access more often.
No PB this time, bummer. The weekend was quite chaotic so I couldnt prep like i would have wanted.

At my 6S 'how does it all feel'/calibration run I it seemed my signal booster stopped working. So my range was already limited.
And it was quite windy, and at an open space airport it's much more of a problem than i am used to. I had a hard time keeping it straight. The tarmac was ok, little wet and rounded in the middle which didn't help either.

Using the innerlane was a bad move, at the taxi turn it was rather bumpy, where it lost control and rolled. After that crash, 2 damaged BSR's and my front suspension acting up, chances for a PB were gone. I still explored some and found some better paths for the future.


View attachment 173525

Maybe speedrunning isn’t so bad after all; this place . I need an Infraction, 1 hour, and 10 sets of Hoons; YIHAAH! .
This is Alpha Romeo Romeo Mike Alpha, ready for take off.

 

[LibertyMKiii]

Using the innerlane was a bad move, at the taxi turn it was rather bumpy, where it lost control and rolled. After that crash, 2 damaged BSR's and my front suspension acting up, chances for a PB were gone. I still explored some and found some better paths for the future.

What happened to all that talk about the Dutch and their OCD about smooth tarmac?

Sorry to hear the first outing was a bad one, but it sounds like you have plans for the next attempt. I would take a look at a weather app before going out and cancel the plans if the wind speeds are to be over 8 mph. It is not worth all the prep time and $$$ to go out and crash.

Looking forward to you getting in a clean run on a wide open run like this!

 

[rotauq]

What happened to all that talk about the Dutch and their OCD about smooth tarmac?

Sorry to hear the first outing was a bad one, but it sounds like you have plans for the next attempt. I would take a look at a weather app before going out and cancel the plans if the wind speeds are to be over 8 mph. It is not worth all the prep time and $$$ to go out and crash.

Looking forward to you getting in a clean run on a wide open run like this!

The tarmac was still above my expectation. I just need to stay clear from taxi turn, at the right lane it should be fine.

If everything goes perfect, there is nothing to learn. I still see it as a success, now I know what I am dealing with exactly and at what conditions. I definitely was too focused on all that, instead of prepping the car itself.

In post analysis, the level grub has lost thread in left A-arm. The signal booster is a mystery to me, I guess it ran too hot some time before today.

 

[rotauq]

Update 42:

My BittyDesign body was scratched some at my airport run. So I decided to try something else than epoxy/FG for reinforcing the body. And went for PUR, it's mass density is very low and with volume it does bring plenty of strength, and less room for air to be. It's become some piece of art if i can say so myself:

Did some rewiring to change the lights.(all red is going blue) And as my bec system failed, I added a separate battery for my lights/cooling.
Used iron wire to strengthen the front.
Cleaned up, oiled up and shimmed all my bearings. I didnt feel smooth at first, but after one run it's all perfect.
The PUR in the body does dampen the sound a little, i like how the high pitch sound is replaced by a more whoosh sound

 

[Sandracer_NL]

Update 42:

My BittyDesign body was scratched some at my airport run. So I decided to try something else than epoxy/FG for reinforcing the body. And went for PUR, it's mass density is very low and with volume it does bring plenty of strength, and less room for air to be. It's become some piece of art if i can say so myself:

View attachment 175793

View attachment 175795

Did some rewiring to change the lights.(all red is going blue) And as my bec system failed, I added a separate battery for my lights/cooling.
Used iron wire to strengthen the front.
Cleaned up, oiled up and shimmed all my bearings. I didnt feel smooth at first, but after one run it's all perfect.
The PUR in the body does dampen the sound a little, i like how the high pitch sound is replaced by a more whoosh sound

Nice work,. Getting ready for the 300kmh I see .

 

[rotauq]

I pulled 214kph (133mph) on 350m(1150ft) with low and cold batteries yesterday. Just testing, slamming it with 6S CH delay hoping it would not fly, and it didn't

Pulling so hard on low charge batteries does cause plenty of voltage sag/amp draw, but it was all about it being a good platform toward 140+mph

If it stays dry today i might do the same run with (fully charged) parallel packs hoping i can keep the voltage above 27V

 

[LibertyMKiii]

I pulled 214kph (133mph) on 350m(1150ft) with low and cold batteries yesterday. Just testing, slamming it with 6S CH delay hoping it would not fly, and it didn't

Pulling so hard on low charge batteries does cause plenty of voltage sag/amp draw, but it was all about it being a good platform toward 140+mph
View attachment 176053
If it stays dry today i might do the same run with (fully charged) parallel packs hoping i can keep the voltage above 27V

That is impressive for 1150 ft!
I think if you have more road to use a 7sec delay will be better. The amperage should drop a good bit with a slower throttle pull to 100%

 

[rotauq]

That is impressive for 1150 ft!
I think if you have more road to use a 7sec delay will be better. The amperage should drop a good bit with a slower throttle pull to 100%

On my regular road i am not gonna beat my PB, so it's all about low risk tweaking until a Monday comes up with good weather/not to busy at work so can try it at the airport.

I see it as two birds in one stone,
testing the chassis for absurd acceleration (with no risky late braking)
and a benchmark run for voltage sag comparison.

Also i ordered a new booster and long attenna's to get my range back. I was running short at the airport.

 

[LibertyMKiii]

On my regular road i am not gonna beat my PB, so it's all about low risk tweaking until a Monday comes up with good weather/not to busy at work so can try it at the airport.

I see it as two birds in one stone,
testing the chassis for absurd acceleration (with no risky late braking)
and a benchmark run for voltage sag comparison.

Also i ordered a new booster and long attenna's to get my range back. I was running short at the airport.

Sounds like the car is certainly dialed in now accelerating and braking in such a short distance.
Can't wait to see what you can do with it!

 

[rotauq]

Been busy with work but i managed to do a quick comparison run on 2x2x4S during my break.

Same distance, almost same top speed. Big dip in my throttle confidence and i braked a little earlier. Very happy to see it stayed on 28.5V.
Sadly the rpm log is weird, peaking at double rpm's just before the braking. Based on the sound i heard the peak wasn't there (42k rpm is no load/max throttle with this setup), so no lose pinion or anything. I did 2x 0-40 drag test afterward without a problem. (1.35s)
It just sounded like willing to keep on going forever, there are definately a couple more k of rpm's left in there if the road allows it

 

[rotauq]

As I had to get my batteries back to storage voltage i went out for an other quick run.
Again weird rpm spikes in the log (and more ripple), but again it all sounded normal.
Starting with 32.6V it dropped to 26V

I continued again with a few drag runs where i could definitely tell rpms sounded normal it also spiked

 

[LibertyMKiii]

I wonder if that RPM spikes is center shaft vibration/harmonics? That looks oddly similar to what others were experiencing and how their RPMs jumped around like that. From memory once that occurs the acceleration stops.

Odd given your setup shouldn't have that happening...

 

[rotauq]

I wonder if that RPM spikes is center shaft vibration/harmonics? That looks oddly similar to what others were experiencing and how their RPMs jumped around like that. From memory once that occurs the acceleration stops.

Odd given your setup shouldn't have that happening...

The big question is, is it only the logging or does it affect the ESC as well. Pure on the sound i heard i'd say it's only the logging.

I would be really surprised if there is much vibration/harmonics from the centershaft. I could quite easily check by doing a run with my gopro aimed at it. That would also record the sound, which would give a better indication of the actual rpm behavior.

My rear tires wore a lot during the drag runs (before and after the second speedrun) It could also be a source of vibration.

Other thing i noticed is the ripple. I am currently running an older, small ripple pack that might have seen it's better days. On the first run it was still perfect, after it's different. It never gone much above 1V. I am considering to remove it. Other option is to try running it with my other XLX2 which has a bigger and much newer cappack. It's built in my FG, i am not keen on taking it out, so that would be a last resort.

 

[LibertyMKiii]

The big question is, is it only the logging or does it affect the ESC as well. Pure on the sound i heard i'd say it's only the logging.

I would be really surprised if there is much vibration/harmonics from the centershaft. I could quite easily check by doing a run with my gopro aimed at it. That would also record the sound, which would give a better indication of the actual rpm behavior.

My rear tires wore a lot during the drag runs (before and after the second speedrun) It could also be a source of vibration.

Other thing i noticed is the ripple. I am currently running an older, small ripple pack that might have seen it's better days. On the first run it was still perfect, after it's different. It never gone much above 1V. I am considering to remove it. Other option is to try running it with my other XLX2 which has a bigger and much newer cappack. It's built in my FG, i am not keen on taking it out, so that would be a last resort.

My thoughts exactly with the GoPro

@Edough13 was having that issue and when the ESC reads this as odd RPM back EMF the acceleration stops. That was blocking him from reaching his speed goals...

 

[rotauq]

I did some minor tweaks. replaced a cup, removed cappack, added padding on the esc and drop the pinion 3T to get some extra rpm's in there. Gopro mounted aimed at the shaft.
It was to windy to do the full benchmark run. It hit 113mph on an aborted run. So I switched to 30k rpm burnouts and this picture shows the maximum bend, hardly nothing. The little it does seems more to be due it not being entirely straight (anymore) on slow acceleration it's more wobbly, but in the tolerance i would expect from 2 dogbone connections.

 

[LibertyMKiii]

Seems OK
Did the data logs show any of the RPM spikes again?