G-force meter.Almost as good as a dyno:)

[Jozzer]

Just got hold of one of these http://www.escortradar.com/gtimer-specifications.htm .
It measures g-force, and can do timed runs and 0-30 or 1/4 mile etc.

Ran the kmx around a bit playing wit the different features, and came up with these measurements.
0-10mph 1.85 secs
0-20mph 4.52 secs
0-30mph 12.28secs
1000ft 28 secs
660ft(1/8mile) 18.4 @30.8mph
330ft 11.8
60ft 3.95

With the weigt of me and the trike inputed, it reckons this equates to 3.4HP (I was pulling around 2kw, I assume the discrepancy is due to the geared hubmotor or the fact that cars have high transmission losses and this is factered into the units calculations)

This test was done at 66v, I'll make another few runs at 82v later (when the mothers have finished clearing their kids off the streets :lol: ).

The meter seems like it will offer clear comparisons between different bikes/motors, but has one drawback for E bike use, it need to reach a good 30mph before it records the run.

BTW, i bought the unit cheap from here. http://cgi.ebay.co.uk/ws/eBayISAPI.dll?ViewItem&rd=1&item=260154127815&ssPageName=STRK:MEWN:IT&ih=016
They are offering new units cheap to 1 off buyers, so they dont cause the price to drop for more serious users (racers/car manufacterers)...or at least thats the story!

 

[knoxie]

Hi Jozzer

Very interesting! be nice to run one of them as well, I have enough to ensure I can make some decent comparisons.

I will take my KMX out a bit more this week, the weather is nice at the moment it would be s shame not to make the most of it whilst I can, I noticed today the leaves are starting to turn!!

I went out to the site of that UFO velo today, I am pretty sure the guy works at the Renault factory, he was heading right in that direction, I dont think my KMX will stay with him, I watched the video again and using google earth it seems he is doing an average of 44mph, I cant do that on the KMX, thats pretty fast on the KMX as well, twitchy!

You will have to do some more video of your modified Puma, how does it compare to the 408?

Cheers

Knoxie

 

[Jozzer]

Hehe....45mph on the KMX is indeed pushing it a little Its got a short wheelbase though, an easy fix would be to make an extender so you could drop the rear wheel back a foot. Even cooler if you could make it happen at the click of a switch :lol: (how very James Bond).

The puma is way faster than the 408 as far as accelleration goes. The X'lyte feels a little better between say 25 and top speed though. By tis speed I think the Puma has given up its advantage, and perhpas is even losing out due to overreving motor. Economy is about equal when going easy (pedal starts and not too much accelleration/ills), but the x'lyte would get very poor wh/mile figures when pushed hard/hills/racing/handbrake turns etc), wereas the puma just slightly increases its average consumption under stress.
shame the x'lyte died before I could get some runs with the g-meter, but the puma is way faster off the line.
I had a 4011 in there recently at 82v, and it couldnt climb a hill as fast as the puma at 60v...

I'll get young NickF back ere for more video's with his camera soon (before the leaves cover the road. Honestly, I thought spring had just started!)

Long live the Puma :lol:

 

[xyster]

0-10mph 1.85 secs
0-20mph 4.52 secs
0-30mph 12.28secs
...

The puma is way faster than the 408 as far as accelleration goes. The X'lyte feels a little better between say 25 and top speed though.
I had a 4011 in there recently at 82v, and it couldnt climb a hill as fast as the puma at 60v...
...

Long live the Puma :lol:

Interesting numbers. If they're accurate, the Puma is quicker to 20mph but slower to 30mph than my 5304/20" at 72v 35a. Which wouldn't be surprising since the Puma is a lot lighter, and the 5304/20" starts to pull its hardest around 20mph. You've got a huge aero advantage with the KMX, however.

Lowell's 5304/20" with a modified controller and 98v nominal (around 80 v under load with his NiMH pack) does 0-40mph in 7 seconds on an upright bike.
http://endless-sphere.com/forums/viewtopic.php?t=1660&highlight=acceleration
I'd be very surprised if the Puma could come close to that without burning up first. Who's game to try?

 

[Lowell]

For a 0-40mph pull, I wonder if motor cooling would be an issue at all? If not, the only thing that might give out are the gears. How about a Puma with liquid cooling and all steel gears

 

[Jozzer]

yeah, lowells x5 is running at like 6KW tho
I'll try for a 0-40 time @ 82v, but that definitly envolves breaking the speed limit round here...an activity I'm trying hard to avoid!

Low wind resistance and lightness may help alot, the kmx weighs in at only 28KG. Rolling resistance is high however, 3 fat tyres. The linear recumbent I had last year was much better tan te KMX for speed.
I'm pretty sure tough that the only way to get into lowels league will be to fit an X5(got a controller ready to go tricked up to 60A), or to do better fit an Etek to the poor trike :lol: Dont think the KMX needs either TBH, its great at this weight, and any more power will definitly get me noticed in the wrong way!

 

[Jozzer]

Liquid cooling would be nice, but cant see a way it could be done TBH. Too litte access space, and no space for tubing between coils anyway. Oil cooling is a possability, I think you can run motors in mineral oil safely, but not sure wat that would add in the way of drag! Still be tough to get the oil out to a rad though...

 

[fechter]

How about liquid nitrogen injection

That would look cool with the vapor streaming out. Even liquid CO2 would be good. Sort of like nitrous for an electric motor.

You could also pre-chill the motor before the run and rely on thermal mass to prevent it from overheating.

 

[knoxie]

He He

I like, funnily enough its not the gears that suffer under high loads they are fine, its the flywheel and the rotor shaft, they are only a press fit and I have known them slip and need welding, of course heat is an issue and I bet the motor does get pretty hot at 2KW power levels, Joz should be ok as we are cooling off a little out there now, I ran the BMX for miles and miles in the winter at 72V and the motor barely got even warm, well it was like 5 or 6 deg outside! ha ha.

Blighty is good for one thing! keeping motors cool! ha ha, good luck with the fault finding Jozzer, I am going to do test number-2 on the motor tomorrow I reckon, the weather looks good all week and I am off work. Plenty of KMX riding as well, that things a blast to ride I love them, I find mine rolls really well? super high pressure in the tires helps.

Easy

Knoxie

 

[Jozzer]

lol at the liquid gasses idea.

As Knoxie says though, its cooling down here now. I just used 3AH of juice at 82v trying to get a reading from the g-meter (failed, it said "must reach 30mph" even when I got to 43mph and my heart made me slow down.I'll try again tomorrow, tink I need to remount it to stop vibration), and the motor was just 28C when I got off! Left for 10 mins, reads just 32c. The motor did 5 full speed runs from 0-40+ running 82v and 35A (2850w before losses, DB showed 2500w I noticed at one point), all in 10 mins! Either its very efficient, despite the high power, or its saving all the heat deep inside forever! I mean, its cool outside, but not below 18c....seems amazing.

Mine rolls OK too, and I now have a slightly skinnier tyre on the rear which helps a bit. I would have been very impressed if I hadnt had the Linear first. The linear DID have great road race tyres though, both skinny, very high pressure. The KMX makes up for this by being able to handle grit/track/snow/rain...all of which terrified me on the linear!

 

[Jozzer]

Actually, a small gas nozzle WOULD fit through the axle with a bit of persuasion, and since the wires going throught he axle would be supercooled they needn't be so fat :lol: I suppose a larger hole venting through the sidecasing would be needed, but since airflow would always be leaving the motor under pressure no crap would enter...
If thermal limits ARE the only concern here, then I can see an attempt at Lowells x5 speedrecord actually working with a puma :lol: (at least untill he rises to the challange and adds nitrogen cooling to his x5 too )

Precooling is out of the question, the girlfriend says theres no way I am storing the Trike in the freezer :x

 

[xyster]

Precooling is out of the question, the girlfriend says theres no way I am storing the Trike in the freezer :x

Just put it underneath a bunch of frozen meat -- she'll never notice. I kept my extra lithium batteries in the fridge behind the butter.

 

[knoxie]

Yo

Glad you are having some good runs with it, you would be able to stay with the mystery velomobile man with that kind of pace, I love the KMX but over 40mph its twitchy, I am much happier at 30 max, I will have to tail the velomobile on my motorbike.

Cheers

Knoxie

 

[Jozzer]

Hey, i'm with you. I'm nearly over 40 myself, and thats as close to over 40 that I want to go these days! It was a white knucked ride along my street I can tell you!

The KMX feels grand at 82v though, ultra responsive. Top speed is too high for sure. Perhpas one of the "slower RPM" puma's will feel good and not be too fast?

Its a little bizzarre that the motors dont get hotter (I thought I had burned one out, but it actually seems OK now I look at it, and it only got hot due to an incident wit the "handbrake" on the KMX.).
I wish I had put a temp guage inside as well as the thermostat

 

[xyster]

The KMX feels grand at 82v though, ultra responsive. Top speed is too high for sure. Perhpas one of the "slower RPM" puma's will feel good and not be too fast?

Is there any way, without major surgery, to put a 20" wheel on the rear of the KMX? Love 'dem smaller drive wheels....

 

[Jozzer]

Hehe, my bums already only 5 inches off the tarmac :lol:
A bigger wheel would be nice, but wont fit (despite what everyone tells me). Bigger wheels on the front are on my list of fun things to do. As it stands the KMX grounds easily if you ride offroad if there are bumps over 4 inces or so.
Really I suppose its great just as it is (at the lower voltage of 66). Perfect speed and nice power without wasting too much on that demon speed, its just I cant bear the thougt of it being "finished" :lol:

Xyster, you need to get a KMX, you clearly havn't got the idea of what its actually like :lol:

 

[Jozzer]

Hmmm, I just found out that the guys who made this dont like shipping out of the USA. looks like i'll have trouble getting the data lead to connect to the PC

 

[xyster]

Xyster, you need to get a KMX, you clearly havn't got the idea of what its actually like :lol:

True, I've never ridden anything like that, which is why I asked the questions I asked. It sure looks like fun.

 

[cadstarsucks]

Its a little bizzarre that the motors dont get hotter (I thought I had burned one out, but it actually seems OK now I look at it, and it only got hot due to an incident wit the "handbrake" on the KMX.).
I wish I had put a temp guage inside as well as the thermostat

Not really. The losses in the motor are primarily resistive and the controllers are controlling the motor current.

Dan

 

[Lowell]

G force based performance meters seem to give widely varying results compared to a real dragstrip. I will have to try my Vericom and Gtech Pro on my bike...

 

[Jozzer]

These guys reckon you can get reliable results at a dragstrip, but then, they WOULD say that :lol:
I wonder if it is MORE reliable on a smaller slower vehicle, or less?

 

[Jozzer]

Ok, got a couple of clean runs at 82v.
0-30 10.17 secs.
0-20 5.1
0-10 1.87

2 secs faster to 30mph. funny how much difference a couple of secs makes to the ride.. :lol:

 

[xyster]

Ok, got a couple of clean runs at 82v.
0-30 10.17 secs.
0-20 5.1
0-10 1.87

2 secs faster to 30mph. funny how much difference a couple of secs makes to the ride.. :lol:

Yes, it sure does. That's the same 0-30mph time as my upright bike X5 at 80v35a with me in a normal upright position, but the Puma is much quicker to 20mph. Seems the 5304/20" begins blasting-off at about the point the Puma is poopin' out.

 

[Jozzer]

Sounds about right. Not sure its pooping as such, just that it pulls much better lower down. I wouldn't mind betting even the 4 series x'lyte has similar 20-30mp figs. (MUCH slower 0-20 though)
whats top speed on that X5 xyster?

I think thats about the best results i am going to get from this set up (unless I recreate that 95A scenario ). I'm very happy with the results from the Puma. What a great little motor

 

[xyster]

whats top speed on that X5 xyster?

40mph fully charged, on the level, normal upright body position.