Bikes and land speed records
Sun, 18/12/2011 - 12:37
Kevin,
Just read your tech watch special articles regarding ultra high speeds and powers, in MCN.
The speeds and powers involved are truly mind boggling. Incomprehensible. Most of us can only use our imagination, the best we can, to try and understand what it must feel like at those figures.
Couple of things spring immediately to mind.
You finished by saying a bike only has one wheel through which to deliver power to the road. What about the front wheel? Has anyone tried to use the front wheel to transmit a portion of the power in land speed attempts?
Is it allowed in the rules?
Also, given the enormous amount of air flowing through an engine producing upwards of 700 hp, what kind of thrust is potentially available from the exhaust pipe(s)? Has anyone tried to use this in land speed attempts. Either the direct thrust or other subtle ways?
Thu, 22/12/2011 - 18:35
#2
Re: Bikes and land speed records
Brilliant. Thanks a lot.
Regarding hydraulics, there are very efficient axial piston pumps and motors which are up in the mid to high 90 percent efficiency region, and reasonably compact. Mind you, even 3 or 4 percent is a lot of heat at those levels of power. Even if we tried to get only a quarter of the overall power though the front, we're still looking at transmitting 200hp ish. Youch!
With my mad professor head on, and given sufficient funding ( ha ha) , I'm thinking an hydraulic motor on top of each fork leg driving shafts to bevel gears on the axle. Unsprung weight? Pah!
Talk about Wallace and grommit!
Thu, 22/12/2011 - 18:47
#3
Re: Bikes and land speed records
The pumps can be efficient but there are big losses in the pipework too, plenty of friction/viscosity drag and inertial losses from the oil changing direction. You'd probably boil the stuff at these power levels!
Yup, it's a bit The Wrong Trousers, only with more horsepower...
Sat, 31/12/2011 - 17:20
#4
Re: Bikes and land speed records
Hi pittsy,
I work and test VOAC bent axial hydraulic pumps and motors and other pumps and motors.
The VOAC's are very well designed hydraulic pumps and motors.
You are right their volumetric efficiency is often 95% or better but their overall efficiency on the VOAC's on the pumps I have tested are about 85%.
Overall efficiency is volumetric efficiency times the mechanical efficiency.
Most of the hydraulic piston pumps and motors that I test have an overall efficiency of about 80% to 83%.
One LSHT (low speed high torque)hydraulic motor I've tested has a low overall efficiency of about 65% to 70%.
If you have a hydraulic pump with an overall efficiency of 83% driving a hydraulic motor with the same overall efficiency of 83% you get a total total overall efficiency of .83 x .83 or about 69%.
Throw in plumbing and control valve losses and it drops even further. A good typical system may be only about 60% efficient.
So for every 10 HP you put in at the pump's shaft you only get out of the hydraulic motor's shaft 6 HP. That's a 40% loss.
That's not very good compared to a standard transmission and final chain drive at about a 12% loss.
Of course as Kevin indicated that 40% loss simply turns into heat and now you have the added additional expense in energy and components to handle the problem of cooling the system to within safe operating temperatures.
Either that or have one monster of a reservoir or tank.
JAG
Sat, 31/12/2011 - 17:21
#5
Re: Bikes and land speed records
Thanks jag.
Gulp. That's a lot o heat to get rid of and a helluva waste of power.
Back to the drawing board.
Sat, 31/12/2011 - 17:44
#6
Re: Bikes and land speed records
Hub centre steering. With chain drive on each side and CV joints into the wheel hub.
Another idea is a single sided hub centre arrangement like the Yamaha GTS1000. On the "free" or open side would be an arm attached to the main frame and carrying a drive, either chain or shaft. Then a driveshaft exactly the same as a front wheel drive car "jumping" across and driving via a CV joint.
Nuts I know but what the heck.
Mon, 02/01/2012 - 11:17
#7
Re: Bikes and land speed records
Yamaha and KTM both built motocrossers with hydraulic FWD. Totally different ball game obviously as the power involved is very small compared to what we're discussing above. The amount of heat to dissipate is small even though the losses are high. Presumably the loss of horsepower was worth it for the extra traction gained.
Telelever suspension would lend itself better to the routing of hoses. But doesn't lend itself to long travel suspension!
I seem to recall vaguely, that someone also either built or at least drew up plans for a bevel drive mechanical FWD system. Not sure?
Tue, 03/01/2012 - 14:15
#8
Re: Bikes and land speed records
Now you lot have all been making me feel a little thick recently, what with all the talk of power thrust curves, cross plane crank torque, fuel system pressure theories and so on. Made all the worse by the fact that I am a technical guy but obviously it has been so long since I studied engineering theory that I have forgotten most of it!
Anyway I can at least add something again and in my ever permanent quest to notice interesting and novel things related to bikes I saw and snapped the picture attached. All this talk of hydraulic motors, pumps, universal joints - pah all complicated nonsense. There is nothing that can not be achieved without an old starter motor, ring gear and imagination. Now it was part of a three wheel drive system on a Honda CX500 with side car and yes I admit it may not be much cop in a land speed attempt but humour me and let me feel like I am part of the team again.
Tue, 03/01/2012 - 15:24
#9
Re: Bikes and land speed records
Thanks shuggie.
A good device for getting that initial torque to gain traction.
Listen, I don't regard myself as clever either, just a nutter. You'll notice a trend. I dig myself into a hole, sometimes a very deep hole. Then wait. Pray. That someone who knows what the heck they're talking about comes along and gets me out!
Looking at your picture reminds me of the guzzi three track army vehicle. Mulo. Did it have FWD?
.........Just looked on google and there's a video of one. It had FWD. 20% torque to front. Rest to rear.
Tue, 03/01/2012 - 16:18
#10
Re: Bikes and land speed records
Shuggie,
Your CX combo front wheel starter motor affair. This may have been a form of reverse "gear" for the machine. That would be the most likely use of it I would hazard a guess.
Tue, 03/01/2012 - 16:40
#11
Re: Bikes and land speed records
Possibly could have been. That would be even sexier than the Yamaha and KTM attempts, front wheel drive to go backwards. Mind you given the lack of grip that there was there I think it may have been used for forward progress in helping to actually keep a bit of traction on the steering wheel. It had a very clever third wheel drice affair on the chair wheel, I have pictures of that too somewhere. I am not saying that it was mega effective but full marks for trying I say.
Tue, 03/01/2012 - 18:02
#12
Re: Bikes and land speed records
Hydraulic drives can usually be reversed by fitting suitable control valves. Jag is the man to advise better on that one me thinks.
Now that we have you on this side of the fence, can we tempt you into commenting on any other recently discussed items?
Got any pictures of a Stirling engine? Narta mean. Nudge nudge. Say no more. Eh? Eh?
Tue, 03/01/2012 - 21:53
#13
Re: Bikes and land speed records
I'm not a technical man, I can hear the whistle as many recent post fly over my head, but I'm assuming a drag bike needs minimal steering? If so could you not just use a similar system to that used on 4x4 cars and stick a shaft down the outside? Need a bit of a gap to give a bit of front wheel clearance but should be possible. Might be a pig stability wise with all that weight hanging off one side though!
Speaking of which.... how about moving the steering bit further back down the frame? Bit of clever trickery needed Gromet to give a semblance of stability but I'm sure you chaps have the neccesary. Is rear wheel steering definately out of the ball park?
Tue, 03/01/2012 - 23:48
#14
Re: Bikes and land speed records
Hub centre steering. With chain drive on each side and CV joints into the wheel hub.
Another idea is a single sided hub centre arrangement like the Yamaha GTS1000.
With that unsprung weight you'd need to be riding from dentist to dentist...
Several years after the GTS1000, I interviewed the Yamaha engineers behind the project, and remarkably they admitted the original plan was for the GTS1000 to be the FZR1000 replacement, it was meant to be the new Yamaha superbike, but they simply could not get hub-centre steering to work as well as good ol' telescopic forks. And this was Yamaha, not some bloke in a shed, who usually has the full rights to hub-centre righteousness. They put huge resources into this project too, hoping to ace the rest of the world with it.
Wed, 04/01/2012 - 10:07
#15
Re: Bikes and land speed records
Silvercub
You'll no doubt be familiar with the ROKON 2 wheel drive motorcycle. You seen the RACOON hydrostatic 2 wheel drive?
Wed, 04/01/2012 - 14:24
#16
Re: Bikes and land speed records
UcR
I was thinking the same thoughts. I have zero experience of hurtling along at 300 mph, but I wouldn't imagine there'd be an awful lot of steering going on. I suppose the bonneville flats don't feel that flat at 300 mph either!
Unsprung weight. Move the braking system in board. Like on mid 70's renault cars or 30's BMW bikes. Another idea for drive is a heavily crowned and barrelled pinnion. Driving into a ring gear cut into the hub. Would have limited range of movement. Utilising the hub centre steering though unfortunately. Presumably a tyre on a driven wheel gets hotter than one on a non driven wheel? If so, there's another incentive for 2 wheel drive. Lower the running temperature of the rear tyre.
At the end of he day it would take a very brave person to risk anything radically different at those speeds. Small increments is probably the order of the day.
Wed, 04/01/2012 - 14:52
#17
Re: Bikes and land speed records
Wow Pittsy, that is one weird bike! I shall show it to our mutual webmate Shuggie on the Monkeystrada thread. If you don't mind, old bean.
Wed, 04/01/2012 - 15:58
#18
Re: Bikes and land speed records
Not at all.
Just less of the old! :-)
Wed, 04/01/2012 - 16:08
#19
Re: Bikes and land speed records
Silver cub: "Wow Pittsy, that is one weird bike"
It is.
We like that.
Backwards at 40mph sir? Just engage this lever here and.... Woo ah. Steady, ah say steady there boy.
One would assume it has infinitely variable transmission. Be awfully disappointed if it didn't.
Ability to apportion torque to wheels as desired? Don't see why not. (mind you, there's a lot of things I don't see)
....Pulling logs up slopes, dragging elephants out of swamps, digging boy scouts out of horses hooves....
Wed, 04/01/2012 - 20:01
#20
Re: Bikes and land speed records
Seen a similar bike at an agricultral show ealier this year, seem to remember a military application too.
Had a reverse on the old Ural outfit, that could go pretty quickly backwards too. Had to keep a firm hand on the tiller though or the resulting tank-slapper would spit you right off, the bike would then right itself, slow down and stop in it's own time. Apparently watching this is very funny. So funny in fact no one came to ask how I was.
Wed, 04/01/2012 - 20:13
#21
Re: Bikes and land speed records
UcR
You're right. I couldn't help but LOL at the thought of that.
Remember those Messerschmidt 3 track cars? Like an aircraft cockpit on wheels. Similar to bubble cars. Apparently you had all forward gears available as reverse. All you did was flick the advance/retard lever right over and the 2 stroke engine ran backwards.
Wed, 04/01/2012 - 21:04
#22
Re: Bikes and land speed records
That's all right Pittsy, I'd laugh too if it wasn't for the limp.
I do like those Messerschmidts, I'd love to own one someday. A mate had a Heinkel a few years back (with no reverse at all if I remember?), I liked that too but everybody laughed at him when he drove it so he traded it in for an old Lotus. Ironicaly while the Heinkel stayed firmly on the ground the Lotus took off during the Great Storm in '87 and demolished his front porch. We laughed at that too.
Wed, 04/01/2012 - 21:14
#23
Re: Bikes and land speed records
Just remembered I drove a Bedford TM artic with a Detroit 2 stoke diesel, not a land Speed Record breaker but very fast. You had to be careful when first pulling off because sometimes they'd start with the engine running backwards which could be quite alarming for anyone behind you.
It died while I was pulling an illegal shortcut down the Embankment in London while working on the Docklands development & racing with a mate to a railhead. I took my foot off the accelerator to stop at a set of lights only the engine carried on accelerating. I used the clutch, switched the engine off and sat there while the engine screamed it's tits off running on sump oil, and laying down a smokescreen that would have been the envy of any convoy captain. Once the con rods finally came through the crank case I called my boss and legged it before the old Bill came to see what the bovver was.
Wed, 04/01/2012 - 21:32
#24
Re: Bikes and land speed records
So. You had a hole in your engine and the police were looking into it....
Ello ello ello.
Was sis ere then?
Looks like conrods from an old Detroit diesel sarge.
Thu, 05/01/2012 - 00:04
#25
Re: Bikes and land speed records
Great stories !
When I was just a kid by brother and I built a go-cart out of wood. We picked an old 2-stroke lawn mower engine to drive the thing. It must have been all of about 1 ½ HP. Open exhaust of course and smoked a little.
Since it was a vertical shaft so we put a pulley on the bottom and another pulley on the rear axle. I found out you could twist the belt pulley to drive the real live axle.
Our goal was to go around the block once without it breaking down by the end of the summer.
We did have one small hick-up which was that when we put a pulley on the steering wheel shaft and a few ropes to turn the front wheels we didn’t put the ropes on quite right so when we turned the steering wheel left it turned right. No real problem so we didn’t change it.
Toward the end of the summer we finally got it to run almost around the block.
On the last day I was driving the thing and was about half way around the block. I was soooo proud. Even the neighbors came out and started waving at me.
Blasting along at about 10 MPH I waved frantically back. Man I felt good.
It was only when I slowed down for a corner I realized that the little blasted wooden thing had caught on fire from the engine’s exhaust.
That’s why the neighbors were waving at me.
JAG
Thu, 05/01/2012 - 09:48
#26
Re: Bikes and land speed records
Jag: "when we turned the steering wheel left it turned right. "
Ha ha ha.
For once, a vehicle that gets easier to drive the more drunk you are.
We used to call those wooden karts with pram and pushchair wheels "guiders". Kids in the more affluent area of town called them "bogeys". None of them were anything like as advanced as your contraption though. You sure you didn't have your dad helping out there?
Although I did build a fully enclosed version for my brother (no way I was going to test it. :-D ) made from cardboard boxes. I can lay claim to inventing the crumple zone.
Thu, 05/01/2012 - 11:16
#27
Re: Bikes and land speed records
Yes pittsy, my dad helped us out in the beginning.
He was good that way with us kids. We'd come up with some crazy idea to try to make something. He then would give us some bits and pieces and a few tools and then let us go at it. Mistakes and all. You can learn a lot when you screw up.
When we first got the little 2-stroke it wouldn't start. We just could not get it to go.
After he got home from work one evening he came out in the back yard to give us a hand.
He was a welder. Imagine having a father that smelt like steel and had big muscles from moving all that metal around. He was a very quiet gentle person.
I'll swear to this day that that man willed that darn thing to start. As a little kid I was amazed that my dad could simply start an engine by pure will power alone.
In fact, it was that experience with my wonderful dad that made me want to become a mechanic. Imagine someone having the magic power to make an engine go.
JAG
Thu, 05/01/2012 - 12:24
#28
Re: Bikes and land speed records
I'm at heart a pump guy pittsy,
As such I really don't want a lot of controls betweem my beautiful pump and the actuator (hydraulic motor) at the end.
We pump guy's say, "let the pump supply what you want, the way you want it and forget those silly controls, they'er only heaters anyway".
So with that in mind I would have liked to use a variable displacement piston pump with a torque limiting primary control and a secondary pressure compensator control.
If you really want to go crazy make the pump a closed loop type. That way you won't need a directional control valve for forward, neutral or reverse. The pump will do it for you.
Setup the pump so that the maximum torque input to the pump's shaft will never exceed whatever horse power you want. When the load on the wheel is less than that value the pump will pump more oil and the bike will go faster. As the load on the wheel increases (going up a hill) the pump will start to de-stroke, but only de-stroke enough to match your maximum input HP setting and the bike's wheel will slow down (like a infinite gear ratio transmission). If the load becomes very high (stall), the secondary pump control (pressure compensator) will completely de-stroke the pump at the high pressure and unload you engine so the engine won't stall. If the wheel starts to move again (pressure drops), the pump will again start to come on stroke but only enough stroke to not exceed you input HP setting and the wheel will increase in speed.
Of course I don't know where you would put that pump or the hydraulic motor on that little bike. Maybe put a trailer hitch on the back and pull the reservoir.
JAG
Thu, 05/01/2012 - 12:39
#29
Re: Bikes and land speed records
Variable swashplate axial piston pump?
Not sure what motors they're using. Look like gear or vane to my un expert eyes. It doesn't seem to have suspension, relying on balloon tyres (need to re visit u tube to be sure about that, so don't quote me!).
Could we use radial piston motors direct into the wheel? Support the wheel direct on the output shaft. They work well at the wheel rpm we're dealing with here I believe. Maybe a lightweight Italian made gear motor is best though?
I see what you mean about controls, but for forest work I would think the ability to apportion torque and rotation direction to front and/or rear as desired would outweigh the power loss. No? Forests can be cold places so a bit of waste heat around the legs wouldn't go amiss!
Would we want fully automatic transmission or one with a sequence of "steps" ? I don't know. Did I hear Silvercub say he was in the forestry line?
Thu, 05/01/2012 - 12:45
#30
Re: Bikes and land speed records
Think of a way to convert the front wheel into a winch and we have ourselves a very handy little device.
Or lethal weapon.
Depends on your point of view!
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Is it allowed in the rules?
I thought about that when I was writing it, there's no reason in the rules why you can't do it, and it would make the problem of getting all that power to the ground a whole lot easier in terms of grip. But I think the issue of getting drive to a steered motorcycle front wheel, especially something like 300bhp or more, is just too daunting (and expensive...). You can't use a chain without a complex universal joint between sprocket and axle, shafts have similar issues and hydraulic drive is inefficient, so you'd have a lot of issues in cooling the fluid with this kind of power being transmitted. I'm sure it's possible but it's a helluva problem to solve.
Top fuel drag race cars have their exhaust pipes angled upwards and the blast from these generates 300kg of downforce. But then they do 0.025mpg - ten gallons in a quarter mile run that lasts 4.5 seconds - so there's an awful lot of fuel and air passing through. I think you'd get some help from the exhaust but compared with the horsepower going through the wheels it's not especially significant.