# Concerning the new power to wheel to weight ratio calculation **URL:** \ **Category:** The Garage\ **Created:** [December 11, 2018, 1:42pm UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854 "2018-12-11T13:42:57Z")\ **Posts on this page:** 5\ **Page:** 3

**Author:** ![ootdega](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.cataclysmdda.org/ootdega/32/3455_2.png) [@ootdega](https://discourse.cataclysmdda.org/u/ootdega)\ **Post date:** [December 13, 2018, 11:08pm UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854/41 "2018-12-13T23:08:20Z")

> [@mlangsdorf](#): > > Electric motors always report speed 0 until you turn them on for the first time. Not 100% sure why, don’t care enough to spend a couple of hours debugging the issue. You could just handwave it with something something computers. Combustion engines can run just fine with nothing but a points ignition system, but modulating an electric motor requires pulse width modulation unless you want to set the vehicle on fire using resistance or voltage regulation. (Don’t quote me on that last part, I’m an unemployed halfway-competent PC hardware tech with too much automotive research under my belt, not an electrician.) I thought that might be the case due to the working electric sports cars that also said zero, but the tank numbers made me question it. I guess it’s good to have confirmation. That said, it would have taken a LOT to get that thing started. Still, if it’s taking the broken treads into account now, why doesn’t it say zero? I’m very confused. > [@mlangsdorf](#): > > and for the same vehicle weight, treads have much more rolling resistance than rollers. So the weight of the wheel itself doesn’t factor in? That’s…unexpected. The weight of the wheel should factor in as much than the weight of the rest of the vehicle, because the engine has to spin it, not just push it. I mean yeah, it makes perfect sense that caterpillar tracks would be hard to roll, but they weigh like half of the drums. That discrepancy is probably not worth the coding effort though, I suppose. ---

**Author:** ![mlangsdorf](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.cataclysmdda.org/mlangsdorf/32/2462_2.png) [@mlangsdorf](https://discourse.cataclysmdda.org/u/mlangsdorf)\ **Post date:** [December 14, 2018, 1:59am UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854/42 "2018-12-14T01:59:39Z")

The electronic motor thing is entirely a bug, and I looked into fixing it at one point but it turned out to be really non-obvious and tedious and meh, I’ve got real bugs to go fix. As far as the rolling resistance numbers go, I agree they’re really non-intuitive. Cake-pie did the research and came up with the numbers, and he cites his sources here: [https://github.com/CleverRaven/Cataclysm-DDA/issues/25652](https://github.com/CleverRaven/Cataclysm-DDA/issues/25652). I would start by reading that issue for an in-depth discussion of the physics and numbers, and if there’s still a problem, file a new issue. As part of the vehicle power display PR I’ve got open, I hoping to be able to display an approximation of vehicle’s new speed numbers for when you add or remove a part. It’s not going to be perfect - for one thing, I’m not going to recalculate drag co-efficients because that’s a very slow algorithm - but it should give people a little more information. ---

**Author:** ![TheZoneWizard](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.cataclysmdda.org/thezonewizard/32/1397_2.png) [@TheZoneWizard](https://discourse.cataclysmdda.org/u/TheZoneWizard)\ **Post date:** [December 14, 2018, 1:04pm UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854/43 "2018-12-14T13:04:49Z")

The rims would allow the vehicle to move. Some crazy people on youtube can be seen driving on rims. Not sure how low a tank is and whether or not it would be possible for those. But for a car or a truck. You can definately drive a vehicle without enough wheels. Now…this will destroy the thing in a few hours perhaps. I say hours instead of immediately, because the metal is actually good enough in most vehicles to allow it to drive. The grinding process would take about an hour or 2. Perhaps off road would be 3. ---

**Author:** ![kevin.granade](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.cataclysmdda.org/kevin.granade/32/1316_2.png) [@kevin.granade](https://discourse.cataclysmdda.org/u/kevin.granade)\ **Post date:** [December 14, 2018, 8:20pm UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854/44 "2018-12-14T20:20:53Z")

There’s a big difference between the damage level where a wheel will fail and make the vehicle unable to move, and a damage level where the wheel is no longer reliable for use and should be replaced. I wouldn’t want to keep using a wheel that had been driven on without a tire for even 10 minutes. ---

**Author:** ![TheZoneWizard](https://sea2.discourse-cdn.com/flex016/user_avatar/discourse.cataclysmdda.org/thezonewizard/32/1397_2.png) [@TheZoneWizard](https://discourse.cataclysmdda.org/u/TheZoneWizard)\ **Post date:** [December 14, 2018, 8:34pm UTC](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854/45 "2018-12-14T20:34:26Z")

I wouldn’t want that tin can either. But that was not my point. Being able to drive on the rims is a feasible function. ( I bring this up as the comment was made asking why a broken track allowed movement) It is also hilarious to watch on youtube of real people doing it making one shake their head in disbelief as they go 50mph down a highway lol xD [Previous page](https://discourse.cataclysmdda.org/t/concerning-the-new-power-to-wheel-to-weight-ratio-calculation/17854.md?page=2)