DIY Electric Car Forums banner

And now for something completely different...

18K views 22 replies 13 participants last post by  Fireman_Mike 
#1 · (Edited)
Folks,

One or two of you may have seen this in a thread I started in the technical forum; here it is presented for your delectation. The Beast, the Object, the Dredd Shed:




What the heck is it, I hear you ask. Well it's a Land Rover 101 FC Judge Dredd. The 101 was a standard British Army truck during the late 70s to early 90s. Basically a standard Land Rover chassis with the seats moved to a Forward Control (FC) position, up and over the front wheelarch, to increase load space. 33 of these were rebuilt by Land Rover for the 'Judge Dredd' movie a few years ago, in which they featured mostly as futuristic taxis. About a dozen still survive, two or three are street-legal; mine is one of them.

It's been rather hacked about - the cab roof has been raised to improve headroom - and it's a bit sad and tatty outside, needs TLC and a damn good respray. It's NOT supposed to be blue either. This is what they're supposed to look like, and what mine will look like when restored:



Inside it's pretty much a shell; they were after all film props, they only had to be driveable for short distances and look good from the outside. Mine will get gutted and a proper interior fitted and trimmed.

Mechanicals... this a standard 101 chassis, what mine looks like under all that fibreglass!



4WD of course, live axles. I would be willing to ditch the 4WD aspect; this thing isn't going to get used off-road! Or maybe... never say never! The above chassis has been refitted with a diesel. The standard power is a 120hp(!) 3.5L(!) V8, with a 4 speed gearbox.

The whole thing is a pig to drive - clutch heavy and nasty, no power steering, lousy brakes, engine noisy and has simply appalling fuel consumption, and the gearbox is the worst, no synchro on 1st or 2nd.

This vehicle is obviously more about 'show' than 'go', but it cries out for something different, very different, very radical in the powertrain department. The stock engine and horrible gearbox are going to be gone, history. What I really want to fit is a gas turbine; I know my way around gas turbines, been playing with them for years. A two-shaft engine, direct drive to the wheels, around 150hp. There's *one* engine that fits the bill; a Rover 2S/150 APU. They're like rocking horse shit - unobtainable. Very rare engine. Strike that idea. An Allison 250 would also work - more power than I need, 250hp, but you don't have to use it all! Problem is they cost a small fortune - if you're incredibly lucky you might find one for $10-15k, more likely $20-25k. I have a pretty open-ended budget for this car but not THAT open-ended.

So, electric drive. Either a pure electric, or perhaps more likely a series hybrid. I still want my gas turbine! You simply can't put a car like this on the road and not having it make an interesting noise! :D I could build a series hybrid with any small one-shaft constant-speed APU engine driving an alternator - exactly the job they're designed for.

The approach and objectives are somewhat different from most EVs as this is essentially a road-legal show car. It WILL be used on the road, but not every day and not for long distances. So range isn't a huge factor, especially if I go hybrid. The thing is a huge box - I could probably fit six battery packs where you guys are struggling to fit one, and hardly make a dent in the interior space available. Weight would be the limiting factor there (kerbside weight is around 2000lb, payload is 1 ton). It doesn't need to go fast; this thing is scary enough at 40-50mph!

I'm still at the early stages of research, playing with ideas and sketching out concepts. I'm reasonably competent mechanically and electrically, but I'm pretty much starting from zero when it comes to EVs. So far, it seems to me that AC is the way to go for a big vehicle like this. I'm not (and never have been) hugely impressed with traditional lead-acid batteries, I'm more inclined to investigate using surplus/junkyard battery packs from Prius or something along those lines. Likely get it running pure electric first, then introduce the hybrid side later... that's the nice thing about series hybrid.

Any thoughts are welcome... apart from the obvious 'He's barking mad! Shoot him!'. Is this too much car for homebuilt EV? Should I just put in a bigger one-shaft gas turbine and use straight electric transmission, forget about the batteries? It's all wide open for brainstorming!

Mike
 
See less See more
3
#3 ·
You're mad!

I love it!

I want one!
:D

I would say go with pure electric and have the sound of the electric motor whine. Maybe put a mic to the comm end and use a PA system to amplify the sound of the brushes arcing?:D

You can probably get a lot of cells within chassis thickness to create a level floor inside. It can then be used for rides.

I think you would do well to keep a gearbox. Maybe get a better one, an auto perhaps, and a part time transfer box. The you can mount the motor to the front of it.

All this depends on your budget really, with a resonable budget you can get a really nice show vehicle if you are not fussed about range or top speed.

I am looking forward to this madness.:D
 
#4 ·
Hello Mike
I second to what Overlander23 said. Take biggest DC motor you can find and use lithium.It will be cheaper than AC and parts are used by others allready.
Build a generator later if you need more range, but you would get going right away.
Great Vehicle:)!!
Regards, Harri
 
#6 ·
...
This vehicle is obviously more about 'show' than 'go', but it cries out for something different, very different, very radical in the powertrain department. The stock engine and horrible gearbox are going to be gone, history. What I really want to fit is a gas turbine;
First off, this is an insanely cool choice of vehicle to convert. I sure hope you are able to see it all the way through to completion!

As for turbines, a small Ground or Auxiliary Power Unit (G/APU) would probably make a decent generator choice for a series hybrid setup but trying to use turbines for traction applications is a lot like trying to run a marathon in ice skates...

Anyway, Garrett made some G/APUs in this size range (the 36-150 is 10kW, IIRC) that might still be had surplus. So did Allied Signal (now part of Honeywell).

Given the amount of driving you will be doing, and the practical limit to the vehicle's top speed, going direct drive (well, through a differential or the transmission locked into one gear, either 2nd or 3rd) would be perfectly suitable. You won't even need that much power/battery pack capacity if you are staying under 40mph and not driving short distances. So, the G/APU turbine thing is more or less strictly eye-candy, but that does seem to be the point of the vehicle, so why not?


... So far, it seems to me that AC is the way to go for a big vehicle like this.
So many people have this impression and I'm curious as to where they get it from in the first place. In industrial applications DC motors still reign supreme above a certain power level (which is getting higher every year), which sorta implies the exact opposite situation is the truth.

AC has some advantages for OEM's to be sure - it's easier to make the motor waterproof and meet EMC regulations, for example - but the best way I know of to sum up the AC vs. DC debate w/r/t EVs is that you can get 2/3rds the power for 3x the price when you go with AC. :D
 
#7 · (Edited)
First off, this is an insanely cool choice of vehicle to convert. I sure hope you are able to see it all the way through to completion!

As for turbines, a small Ground or Auxiliary Power Unit (G/APU) would probably make a decent generator choice for a series hybrid setup but trying to use turbines for traction applications is a lot like trying to run a marathon in ice skates...
Not if you use a two-shaft turbine; a free power turbine set up is perfect for traction (since it produces peak torque at stall; it essentially functions as a CVT built right into the engine). That's what all the gas turbine cars (1960s Indy cars etc) and indeed US Army tanks have used. You're precisely correct about single shaft engines; some people *have* shoehorned single-shaft engines into cars - there was a guy with a Boeing engine hooked up to the auto box on a Porsche 928 - but it's highly sub-optimal and I wouldn't dream of doing it. The only way to use a single-shaft constant-speed/variable-load APU-type engine in a car is with electric transmission.

Anyway, Garrett made some G/APUs in this size range (the 36-150 is 10kW, IIRC) that might still be had surplus. So did Allied Signal (now part of Honeywell).

Given the amount of driving you will be doing, and the practical limit to the vehicle's top speed, going direct drive (well, through a differential or the transmission locked into one gear, either 2nd or 3rd) would be perfectly suitable. You won't even need that much power/battery pack capacity if you are staying under 40mph and not driving short distances. So, the G/APU turbine thing is more or less strictly eye-candy, but that does seem to be the point of the vehicle, so why not?
I think the correct term WRT the turbine is 'ear-candy' :D and I agree with your analysis. I don't have a GTP30 at the moment but I could lay my hands on one. Maybe a GTCP36 would be a better bet, could use bleed air for AC/heating. One way to approach this would be to put in a turbine with a reasonable capacity (say 60hp - I have a couple of those lying around my workshop, see: http://www.corestore.org/turbine.htm ) coupled to an appropriate generator and use that as the primary power source, blending in additional power from the batteries to give an instantly responsive throttle plus additional power for moving off and climbing hills. It's NOT a performance vehicle; the original powerplant is only 120hp to haul around this great lump plus a ton of cargo. Here's the full spec on the original vehicle:

http://www.lrfaq.org/FC/FAQ.FC.101tech.html


So many people have this impression and I'm curious as to where they get it from in the first place. In industrial applications DC motors still reign supreme above a certain power level (which is getting higher every year), which sorta implies the exact opposite situation is the truth.

AC has some advantages for OEM's to be sure - it's easier to make the motor waterproof and meet EMC regulations, for example - but the best way I know of to sum up the AC vs. DC debate w/r/t EVs is that you can get 2/3rds the power for 3x the price when you go with AC. :D

I'm sure I've read, here and on manufacturer websites, that AC is more suitable for large/heavy vehicles. Certainly on the rails, freight locomotives have gone from 100% DC to largely AC over the last 2-3 decades. But I'm entirely open to suggestions. It's not straightforward to compare the power characteristics of motors with the power of ICEs, I know, but are 120hp-equivalent DC motors readily available and is there really that much cost difference to AC?

Would I be crazy to think about throwing away the mechanical transmission entirely, and mounting one motor straight to the diff. on each axle? I'm guessing two smaller motors might work out cheaper than one big one, especially if it opened the door to using e.g. junkyard motors out of wrecked hybrids?

Oh, and just to make things really interesting, I propose to radically change the seating position (the view out the front is somewhat restricted) and do away with the conventional driving controls, moving to a (probably hydraulic) side-stick steering control...

Mike
 
#14 ·
Cool vehicle choice! I've always wanted a 101 - but just don't fit in them (too tall). I saw the Judge Dread vehicles at the Billing Land Rover Show years back and have often wondered what happened to them.
Except for a couple retained for publicity, they were sold off in bulk after filming was completed. Most of them had the Dredd bodies removed and destroyed, and were converted back to standard 101 GS spec. and sold. A couple got used for publicity/show cars by other companies (google 'vibe dredd'), maybe 7 or 8 survive with their original bodies. There were two others road-legal in the UK. One got sold to a noted Land Rover dealer in France, the whereabouts of the other is unknown.

Some backstory on the building of the cars here:

http://www.surreyoff-road.com/judge_dredd_1.html

Mike
 
#12 ·
A very unique vehicle. Seems car and driver did and article on this vehicle when the movie came out. I've seen it before somewhere anyway.

Have fun you have an eye poping vehicle.
 
#15 ·
Time to dust-off this thread. A bit of a hiatus over the last couple of years, during which I acquired a *second* Judge Dredd vehicle (!) and finally had it delivered to my door in NY a couple of weeks ago.

I'm now planning how to take this forward. A good thing is that the engine and gearbox are already stripped out, so I have clean sheet and an empty box to start playing with. I'd be interested to get some advice, and answers to a couple of specific questions on this project.

First, the design parameters:

1. Top speed not to exceed 50-55mph (it's scary enough already!)
2. Given the relatively modest top speed, and the wish for simplicity in build and operation, I've made the firm decision to go with direct drive; no gearbox.
3. Curbside weight as built was around 2000kg. It's lost engine, transmission, radiator, and most of the bodywork so current weight is several hundred kg less than that!
4. Target weight is whatever.
5. Target range is as long as reasonably achievable.
6. It won't be a daily driver, but it will get used on the highway.
7. The ultimate goal is a series hybrid, with power coming from batteries, and a gas turbine generator (think EV1). It should ultimately be capable of running from either or both power sources. The turbine being capable of charging the batteries is not required but is desired.
8. The initial goal is to get the vehicle running as a pure EV, with the turbine series power capability being added later.
9. I am at this stage agnostic regarding battery technology, AC versus DC, 50Hz versus 400Hz.

First, does anyone have any comments on my thinking above. 'Crazy' and 'ambitious' are redundant; I'm well aware I'm both. :)

Second, can anyone recommend resources - websites, forums, project blogs, manufacturers, distributors - where I might get some background, technical information, and war stories, specifically on DIY series hybrids?

Third, can anyone tell me if there are any controllers or power systems available off the shelf that cater for, or are especially suitable for, series hybrid applications? I have little idea at this stage how to go about blending and matching generator voltages & currents versus battery voltages and currents, and switching between the two!

Thanks

Mike
 
#16 ·
Dear Mike,

That's fantastic! I love the Judge Dred vehicles - and they almost deserve to be Electric, at least in part.

Did you buy it from Dunsfold? They are about 10 miles from me.

If you need Land Rover bits, I can recommend my friend Justin Monin who runs Lucky8 Land Rover in Williamsville NY. Anything he doesn't have I can get shipped to you as I run a Land Rover spares company.

I've been thinking about building a Hybrid Range Rover Classic using the AC drive from my Freelander plus a Peugeot diesel engine, both driving into a Suzuki SJ transfer box. The eleccy motor can drive the PTO output and the engine via an auto transmission into the input. That way you can mix the output of the gas and electric engines easily.
I rejected the idea of an engine driving a generator to charge the batteries because of the conversion losses. I love gas turbines - but even still.

I think the most economic solution is to charge the batteries off the mains, run on Batteries whenever you can, but switch to gas when they are getting flat - but not bother charging from the gas engine. That gives infinite range with the economy of electric. The Peugeot diesels are economic but too small to give decent acceleration so I figured using a 'kick down' switch which powers up the electric if you floor the gas pedal running on diesel to give the acceleration when needed.

Keeping a transfer box, even a small, light one like Suzuki keeps the 4x4 capability when required. The Suzuki boxes are normally rear wheel drive with selectable 4x4 which cuts the transmission loss a little.

My Freelander weighs 1.5 ton but still manages a top speed of 93mph and 0-60 in 8.5 seconds which is fairly respectable. Combined with a small diesel it should give respectable performance in a 2 to 2.5 ton vehicle.

Si
 
#17 ·
Thanks for that Simon.

I'm in the USA so UK LR spares are not very helpful to me, but hopefully I won't need much!

That's exactly my thinking on why having the engine recharge the batteries is strictly optional... motor home on the engine if needed, plug it in overnight. Job done.

I have no interest in 4x4 capability for this; the LR chassis just happens to be what the thing was built with. I have the choice of FWD or RWD, and that will be decided entirely on the basis of ease of motor mounting and layout of the rest of the components. So no gearbox or transfer box, straight motor drive direct to the axle - heck I'd even consider an axle-hung motor with the drive going straight into the diff. to avoid the need for a shaft.

I've read of TransWarp motors, supposedly specifically designed for direct drive applications; any thoughts on those?

Mike
 
#18 ·
Cool project, love the look of that thing.

For your conversion I would recommend AC.
You get much higher RPM which is good for direct-drive, and good torque overload at low RPM. Plus AC should be alot more efficient.

But the main advantage in that beast would be regen, with all that mass you get a lot of kinetic energy just waiting for you to convert back into electrical energy during decel. Could save you a lot on your battery pack sizing.
Seems such a waste to accelerate that hunk of metal and then waste all that energy on your frictional disc pads when you need to stop again.
 
#19 ·
The thing is a huge box - I could probably fit six battery packs where you guys are struggling to fit one, and hardly make a dent in the interior space available.
If space is not an issue, get a massive industrial motor like this:
http://www.ebay.com.au/itm/140333768756?ssPageName=STRK:MEWAX:IT&_trksid=p3984.m1423.l2649

170kW, then rewind for delta to get some extra power.. Should bring it up to near 295kW (*sqrt(3) i think)... Burnouts anyone?

The motor probably weighs a tonne on its own though :p shame
 
#20 ·
The main issue you are going to have with direct drive is the motor torque available from the kind of motor you can fit in to the truck is not sufficient.

I found I needed a reduction ratio of 9:1 to the wheel with a 26" Wheel. Your Diffs will be 3.54:1 and likely your Tyres will be 31" or 33" - so you are going to need a further reduction of about 3:1 to give a good combination of acceleration versus speed.

I'm using a transfer box for nothing more than the 2:5:1 reduction in low range. I don't even have 4 wheel drive - though I wished I had in the snow this winter!

The Range Rover project is based on the 1.6:1 reduction in the transfer box plus another 1.5:1 chain reduction from the electric motor.

Si
 
#21 ·
I'm not much bothered about regen/efficiency; this is more about show than go, needless to say!

And I don't exclude the possibility of using a reduction box to get the optimal ratio, I just don't want to get into the business of installing a conventional gearbox.

AC versus DC comments noted; more opinions welcome. I'm still looking for thoughts, and a good reference, on series hybrid principles of design and construction, with special emphasis on electrical and control systems. I don't want to make choices for the initial pure EV build that will make subsequent conversion to series hybrid more difficult that it needs to be...

Mike
 
#22 ·
AC versus DC comments noted; more opinions welcome.
I usually prefer to not kick this horse anymore (it smells funny) since it seems that the same myths gets repeated over and over again and it's tiresome to try to argue against those that thinks AC is the greatest since sliced bread.

My recommendation is ignore whatever technology is used, it frankly doesn't matter. Yes, AC usually has a higher max-RPM, but that means that the torque is lower for the same power so in essence it can be seen as different gearing. It's also hard to claim that just because the top RPM is higher, AC has a wider band. Since both AC and DC starts at 0 RPM both can be used for direct drive, provided the gearing is matched.

Specify what you need (power requirements, weight, budget, regen, ability to cure sick children...) and compare systems. If the system of your choise is underpowered for your vehicle or if you can't afford batteries when you've bought it, it won't be much use for you no matter what technology you've chosen.

Look at it as Diesel- versus gas-powered cars; both systems are fully adequate for getting you from point A to point B and there's usually other facts than the actual technology that decide which one you choose. When you've managed to limit the selection down to those that are actually up for the job of moving the vehicle, THEN you can start considering whether you want to go down the AC or DC path.

My guess is that that day you'll find that considering the weight and the poor aerodynamics of your vehicle you'll find yourself limited to DC anyway. Unless you're prepared to dig down deep, very deep, in your wallet...
 
#23 ·
Thanks Qer, sounds like good advice. Based on what I've read, DC seems to be the way to go on ground of cost, price/performance, and easy availability of important lumps. And for sure it has the aerodynamics of a small home, but that's not so critical if you don't plan on going much faster than 50... and figuring out what I need to move the vehicle is precisely the point I'm at in this exercise!

If I end up with a turbine driving an alternator as the alternate power source, is the rectification of such a big deal to drive a DC motor & control system? Or is that not an uncommon arrangement? I'm *still* looking for sources of information specifically on design and construction of DIY series hybrids...

Been contemplating other possibilities for this vehicle; the load capacity and space available are sufficient I'm seriously thinking of installing a capacitor pack and 100KJ railgun as primary defensive weapon!

Mike
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top