Electric Reverse Trikes. Ideas, Rants, Collaboration?
- Thread starter todayican2
- Start date
chaster
10 W
TomA,
You're putting a lot of thought into it, and that's great. I just want to clear up one misconception:
When the term "ground effect drag" is used, it encompasses several different phenomena. I'm not going to go into turbulence versus laminar flow, nor am I going to go into flow compression underneath the vehicle (although both of those are significant sources of drag). The reason racing cars (in particular NASCAR) focus on keeping the air out from the bottom of the vehicle is to generate a vacuum under the vehicle. You might not be aware of this, but if there was a track available (like something out of the Wachowski Bro's Speed Racer movie), you could almost drive a NASCAR stock car upside down because it generates THAT much downforce from vacuum.
The downside of course, is that you are increasing drag by a significant amount because you are increasing the frontal area.
So, perhaps somewhat paradoxically, by keeping air from underneath a stock car, the drag on the vehicle is INCREASED. But it's a tradeoff that racing teams are willing to make because it improves traction and handling.
Downforce can be generated other ways of course, but since NASCAR has rules on maintaining the basic profile of the car (hence the "stock car" moniker, even though in reality they are nothing even remotely "stock") the front air dam is the most common solution. In Formula racing (and other open wheel racing) there is no such requirement, so you see wings galore (which are far more efficient at generating downforce while minimizing drag increases).
While it is a legitimate concern, I wouldn't worry TOO much about generating enough lift to destabilize your vehicle. I would be more concerned with cross wind stability which is far more dangerous in ultra-light road going vehicles.
Hope this is helpful info.
Eric
You're putting a lot of thought into it, and that's great. I just want to clear up one misconception:
When the term "ground effect drag" is used, it encompasses several different phenomena. I'm not going to go into turbulence versus laminar flow, nor am I going to go into flow compression underneath the vehicle (although both of those are significant sources of drag). The reason racing cars (in particular NASCAR) focus on keeping the air out from the bottom of the vehicle is to generate a vacuum under the vehicle. You might not be aware of this, but if there was a track available (like something out of the Wachowski Bro's Speed Racer movie), you could almost drive a NASCAR stock car upside down because it generates THAT much downforce from vacuum.
The downside of course, is that you are increasing drag by a significant amount because you are increasing the frontal area.
So, perhaps somewhat paradoxically, by keeping air from underneath a stock car, the drag on the vehicle is INCREASED. But it's a tradeoff that racing teams are willing to make because it improves traction and handling.
Downforce can be generated other ways of course, but since NASCAR has rules on maintaining the basic profile of the car (hence the "stock car" moniker, even though in reality they are nothing even remotely "stock") the front air dam is the most common solution. In Formula racing (and other open wheel racing) there is no such requirement, so you see wings galore (which are far more efficient at generating downforce while minimizing drag increases).
While it is a legitimate concern, I wouldn't worry TOO much about generating enough lift to destabilize your vehicle. I would be more concerned with cross wind stability which is far more dangerous in ultra-light road going vehicles.
Hope this is helpful info.
Eric
chaster
10 W
TomA said:
Interesting chart. It says the 5th percentile male is 168.2cm in stature which is about 5'6" tall... I always suspected the average american male was about 5'6" (as opposed to what most people think - which is about 5'9")...
Eric
Thanks so much for the info, Eric.
The 5th Percentile Male is of USAF personnel, not the general population. Apparently, really small guys don't join the Air Force...
I'm sensitive to the crosswind problem, mostly from my study of jets at Bonneville...
I didn't know NASCAR was generating that kind of downforce- at least 3800lbs, if I understand your point about upside down racing. Of course, open wheel cars have been doing that for many years, actually a big multiple of their weight, and they are largely doing it with the underbody and diffusers. The wings are essentially to balance the car, or at least that's what the designers claim in public. I always thought there was an aerdynamic advantage to keeping the air out from under the car, and making it go up or around. Its not too important to me, my undercarriage will be smooth, but if it isn't a big deal, I'll drop the splitter I had planned and get the chin of the car up off the ground where it is likely to get banged up over time anyway.
At the opposite end of the spectrum, Buckminster Fuller was originally deliberately trying to get the rear of the Dymaxion car to lift at speed. His idea was something characteristically flamboyant like "the wheelbase becomes infinite" or whatever. He planned to steer with a rudder in the air stream. Bottom line, that car was squirrely and marginally unstable for other reasons. He rolled it with the whole family inside. Frank Turner rolled it after a collision and got killed. What scares me about that is my dimensions are eerily close to that car, and my front track is probably just too narrow right now. Anyway, here's a photo of the model Isamu Noguchi (yes, that Noguchi) made with Bucky that clearly shows the tunnel designed to trap air. Fortunately, this feature didn't make it into the prototypes...
The 5th Percentile Male is of USAF personnel, not the general population. Apparently, really small guys don't join the Air Force...
I'm sensitive to the crosswind problem, mostly from my study of jets at Bonneville...
I didn't know NASCAR was generating that kind of downforce- at least 3800lbs, if I understand your point about upside down racing. Of course, open wheel cars have been doing that for many years, actually a big multiple of their weight, and they are largely doing it with the underbody and diffusers. The wings are essentially to balance the car, or at least that's what the designers claim in public. I always thought there was an aerdynamic advantage to keeping the air out from under the car, and making it go up or around. Its not too important to me, my undercarriage will be smooth, but if it isn't a big deal, I'll drop the splitter I had planned and get the chin of the car up off the ground where it is likely to get banged up over time anyway.
At the opposite end of the spectrum, Buckminster Fuller was originally deliberately trying to get the rear of the Dymaxion car to lift at speed. His idea was something characteristically flamboyant like "the wheelbase becomes infinite" or whatever. He planned to steer with a rudder in the air stream. Bottom line, that car was squirrely and marginally unstable for other reasons. He rolled it with the whole family inside. Frank Turner rolled it after a collision and got killed. What scares me about that is my dimensions are eerily close to that car, and my front track is probably just too narrow right now. Anyway, here's a photo of the model Isamu Noguchi (yes, that Noguchi) made with Bucky that clearly shows the tunnel designed to trap air. Fortunately, this feature didn't make it into the prototypes...
Attachments
And since it seems to be Trike History Night, there's one little obvious vehicle out there that is practically in my weight class, has the right configuration, an aviation heritage, and represents some pretty innovative thinking, even if its more than 50 years old. Plenty of good lessons to be learned here:
Does anybody know somebody who has one of these Messerschmitts in the NY metro area that I can come look at and talk with them about? That would be a fantastic thing to be able to do.
Does anybody know somebody who has one of these Messerschmitts in the NY metro area that I can come look at and talk with them about? That would be a fantastic thing to be able to do.
chaster
10 W
TomA said:
Nor really tall guys either...
I said "almost". It varies with each car, but they are generating at least 2500-3000 lbs downforce down the straights. Most NASCAR racers are right at the minimum weight limit (3400 lbs if I recall correctly). They could EASILY go lower as they are purpose built vehicles, but that's the minimum. Although I hear that lots of teams try to cheat....
I'm sure I'm out of date with regards to racing technology in F1 since I haven't followed that since college and they generally use the most advanced stuff. I do know that modern F1 cars DO use active aero (they are treating their canards and rear wings like airplane control surfaces and actively changing their characteristics depending on driving conditions) so their claims do make sense.
You know, instead of trying to get it perfect up front, I would say "take a reasonable design and then test". That's what most engineers do when dealing with low RN flow (like automotive applications). You're not dealing with supersonic or hypersonic flow, so you can easily just test and tweak.
I admire Buckminster Fuller. He was ahead of his time in many, many ways. Despite its flaws, the Dymaxion Car was ground breaking in its' design. Too bad he decided to go with rear wheel steer.
May I ask why you are designing a vehicle the size of a bus? (20 ft long)? Are you designing to carry a baseball team?
Eric
chaster
10 W
TomA said:
According to this page http://www.racingcampbells.com/content/campbell.archives/stutz.black.hawk.asp, the Blackhawk lost a tire doing a nearly 200 mph run which caused the fatal crash killing Frank Lockhart. Although it is possible that aerodynamics played a part, the fact that it was his second run (after a successful run at 198mph, and an even faster earlier run at 225 mph) suggests that the aerodynamics were okay. Interestingly, the Blackhawk was crashed twice (once during the 225 mph run) and then the fatal crash. Both crashes were blamed on collisions with road debris or similar.
chaster said:
R. Bucky is one of my heroes, too. I've read 5 or 6 of his books. I thought the tailwheel was the most inspired and interesting feature of his design. The unbuilt last car he designed was 3WD/3WS, which seems to be the best of his Dymaxion Transport ideas. If I had endless resources, I'd be building that.
Did I say dimensions? i meant proportion, but I've stretched my wheelbase inside the envelope, and I'm not steering the rear wheel, so it should be OK. BTW, I am designing a 20 footer, too. That will seat five or maybe seven people, and its actually smaller than the 20 foot length would suggest. I have several cars about that long...
Tom
chaster said:
Well, that's not the full story. What I understand about it was told to me 35-40 years ago by guys who, while none of them knew Frank Lockhart, had vast experience in racing from board tracks to sprint and champ cars all around the midwest. The story went like this: Frank Lockhart was a unique individual. He won Indy as a rookie in a car he had little seat time in. He broke track records everywhere, and was untouchable as a driver. (He was also a designer/builder and team owner, sort of like Ayrton Senna, Adrian Newey and Roger Penske all rolled into one. The respect and reverence that seasoned guys had for him was something to see. Its sad, really, that now he's just an obscure footnote in motor racing history because died so young at 25, never had a chance to develop his ideas or his talent, and hardly any film of him in action exists.) So Frank Lockhart lost control of the Black Hawk twice while driving it in a straight line. The idea that road hazards of one kind or another caused that was pretty unthinkable at the time. Since the wrecked car was buried on the spot, (not uncommon, actually, back in the day,) no analysis of the failure was ever completed. There was, of course, nothing else like the Black Hawk ever built. A close look at the wheel pants on the front shows they are efficient airfoils, and no doubt produce all kinds of forces at 200mph, especially if a tire blew, or the car hit a rut or a piece of driftwood, or any other problem creating or requiring rapid steering input arose. No one knows exactly what happened to Frank Lockhart, but when that car crashed twice, killing the brightest star in American racing, every other car with movable pontoon fenders became suspect. I was also told there were other problems with other cars, including the Tasco streamliner (now in the Auburn Cord Duesenberg Museum,) but I never saw anything about it in print. To be sure, cars of this configuration completely disappeared from Daytona, Bonneville or anywhere else in racing. I forgot about it, and really about Frank Lockhart and the Black Hawk, too. Years later, while watching the movie "Tucker" I almost fell out of my theater seat when the Alex Tremulis character tells the Tucker character that steerable fenders were proven dangerous and he wouldn't permit them on the Tucker car. Well, since the legendary Mr. Tremulis was a technical consultant on that movie, I always took it as validation of the conventional wisdom I'd been told by the midget and sprint car guys who told me a lot of what I know about the history of American racing.
Fascinatingly, there was also a short period of time in Top Fuel drag racing when the skinny front wheels were enclosed in "full fairings" as they were called at the time. The design was started by Lil' John Buttera and Nye Frank in the early 1970s, but by 1976 or so almost every TF car had these wheel pants. I remember hearing, from some of the same old-timers, that those wheel pants didn't look very safe, but that maybe the new kids had gotten it figured out because there didn't seem to be many obvious problems with them, and diggers at the time were only doing 200mph+ for a second or two at the top end. Anyway, its interesting to me how much of this whole steerable airfoil business is now apparently lost- and not found by, say, a search of the Internet. Equally fascinating, and another example of how what's old is always the newest thing: The hot new topic in Formula 1 is- you guessed it- Wheel Pants. This time they don't enclose the tire, and they are more like "fixed wheel covers" than what an aviation guy might think of as "wheel pants," but here they are again- right at the cutting edge of racing aero.
The Bottom Line for me: The conventional wisdom- even if it is very old, mostly forgotten, poorly documented and closer to a belief because it dates from a time when little was really known, and there is just no data other than the Black Hawk crashes- is that fully enclosed steerable wheels inside of moveable airfoils are dangerous at high speed...
Tom
chaster
10 W
Nothing wrong with gleaning wisdom from the past. However, I am also a proponent of taking the time to understand the phenomenon as much as possible instead of relying on "rules of thumb" which are often valid based on certain specific circumstances.
Aerodynamic forces at low Reynolds # are roughly proportional to the square of the speed. Double your speed, and the forces *roughly* quadruple. That's a "rule of thumb" but it's highly generalized and not very helpful in the real world. In reality, there is no substitute for understanding your flow and designing wisely. Even simulation does not adequately replace testing, and rules of thumb don't replace understanding your flow.
I see no problem with the decision to avoid wheel fairings. That's a perfectly legitimate thing to do. But on the flipside, assuming that "all faired steerable wheels are dangerous at high speeds" is a gross oversimplification and is somewhat akin to saying "all light vehicles are unsafe at high speeds".
Eric
Agreed, but:
I (and the conventional wisdom) didn't say "all" and, from the sheer dearth of examples that exist, the number is clearly more than "some" and might even be "most..."
It really doesn't matter for my project, though, its a question of conserving my ability to handle problems. I have very limited resources and have to avoid steep learning curves and potential trouble wherever I can. That, by the way, is a little wisdom about going fast straight from Craig Breedlove.(About 'innovations' in LSR design he said: "You don't want new friends with you in the car if you don't know how they're going to behave..") I'm actually making up very little from scratch. My goal is to select carefully from what has been done before. The aero and composites are the least familiar to me, so I'm being most conservative in these areas. That's why the wheels are staying inside the bodywork. I have other problems I'd rather be solving than working steered wheel pants. I cast an upraised eyebrow at the Aptera not because I don't think they have done their homework, but because it is a lot of homework indeed, in an area so many people have stayed away from entirely for so very long that I thought I would mention it. If nothing else, and to put it completely differently and maybe a little like Bucky Fuller this time, wheel pants might carry ghosts...
Tom
I (and the conventional wisdom) didn't say "all" and, from the sheer dearth of examples that exist, the number is clearly more than "some" and might even be "most..."
It really doesn't matter for my project, though, its a question of conserving my ability to handle problems. I have very limited resources and have to avoid steep learning curves and potential trouble wherever I can. That, by the way, is a little wisdom about going fast straight from Craig Breedlove.(About 'innovations' in LSR design he said: "You don't want new friends with you in the car if you don't know how they're going to behave..") I'm actually making up very little from scratch. My goal is to select carefully from what has been done before. The aero and composites are the least familiar to me, so I'm being most conservative in these areas. That's why the wheels are staying inside the bodywork. I have other problems I'd rather be solving than working steered wheel pants. I cast an upraised eyebrow at the Aptera not because I don't think they have done their homework, but because it is a lot of homework indeed, in an area so many people have stayed away from entirely for so very long that I thought I would mention it. If nothing else, and to put it completely differently and maybe a little like Bucky Fuller this time, wheel pants might carry ghosts...
Tom
todayican2
100 W
- Joined
- Apr 22, 2009
- Messages
- 139
Ok, making progress on my trike planning, found a nice set of spindles etc, from the world of "dwarf" racecars.
I also made contact with a fabricator who can do wonderful things with a tubing bender
So my basic question is this, if I were to go with a side by side, fully enclosed (wheels too) design like the link on the bottom (just to illustrate "fully enclosed, mine would be much wider, about 55" at the outside edges of the wheels) and I would have an overall length of about 118" overall height of about 33"
If I were to go with a tandem arrangement, I would be at about 128" and could pull the body way in and go with open front wheels.
so aerodynamicaly, is it better to be wider but fully faired, or thinner but with open wheels?
http://www.blueskydsn.com/kit_aero.html
http://www.flickr.com/photos/fortinbras/1832710365/
I also made contact with a fabricator who can do wonderful things with a tubing bender
So my basic question is this, if I were to go with a side by side, fully enclosed (wheels too) design like the link on the bottom (just to illustrate "fully enclosed, mine would be much wider, about 55" at the outside edges of the wheels) and I would have an overall length of about 118" overall height of about 33"
If I were to go with a tandem arrangement, I would be at about 128" and could pull the body way in and go with open front wheels.
so aerodynamicaly, is it better to be wider but fully faired, or thinner but with open wheels?
http://www.blueskydsn.com/kit_aero.html
http://www.flickr.com/photos/fortinbras/1832710365/
Congratulations on the Legends chassis choice- they are simple and strong. IIRC, the spindles use a straight axle setup with two upper links, one parallel to the axle and one semi-trailing, like a Mustang II link. Is that correct? Are you going to use that front end, or just the spindles and fab your own unequal length arms? I envy you hooking up with a first class fabricator. that saves time and improves outcomes.
Anyway... When you're talking "fully enclosed design", there are differences in how we all use the vocabulary.
To me "fully enclosed" means that the wheel is completely within the body envelope and only the bottom of tire is visible, like on a Lotus 11 or a 1950s Nash. My trike will probably have front skirts covering the wheels. In order to fully enclose them this way, the body has to be wide enough to accommodate the tires at full steering lock, and you also have to think about brake cooling.
The Mango velomobile pictured in your post has a wheel/tire package that is exposed but basically flush with the outer body envelope when pointing straight ahead. If that's "fully enclosed" to you, fine, just so we understand each other. That's the most logical and practical way to do it, and will give you the narrowest body for a fully fendered design. You might even soften (increase the radius) of the trailing half of this opening, as on the Solectria Sunrise, GM EV-1 and many other cars.
Tandem would give you a an aero length-to-frontal-area-diameter ratio closer to the ideal of 4.5-5:1, but there are a lot of issues involved. If your frontal area is 85% ( a good rule of thumb number) of your 33" height and 55" width, that's about 12 1/2 square feet. The theoretical diameter of that cross-section is right around 4 feet. just rough numbers here, but instructive. Now, 4 and a half times that is 18 feet, almost double your projected length, which suggests your body envelope has more frontal area than is optimal for the aero of your projected length. Your projected length-to-frontal-area-ratio is about 2 1/2:1. If you went with the tandem configuration and exposed the wheels, you might shed 25% of your frontal area. That, combined with the longer length, would increase the ratio to almost 3:1. Still not ideal, but a big improvement. That said, this is a huge oversimplification, and I may be focused on something that is only important to full envelope low-drag vehicles like mine, and almost irrelevant to open wheelers with other aero issues. Eric can chime in here as he sees fit...
The question "aerodynamically, is it better to be wider but fully faired, or thinner but with open wheels?" really depends on many things, including how wide your tires are, how well you can clean up the air moving around the exposed wheels and suspension, (like the Aptera or a Bonneville lakester,) how sleek or bulbous either alternative body style is going to be, especially around the wheel openings versus wheel pants, etc. etc. There is no one obvious answer for every design package, but I would think if your full envelope trike is in danger of having the proportions of a frog and not a tadpole, then a cross-sectionally smaller open wheel design might be a better approach.
Incidentally, so long as these vehicles are going to be electric (under-) powered, I don't see any benefit to wide or low-profile tires. They weigh more, use more energy to roll, create more aero drag, and put more force into the chassis. I will be using motorcycle tires, which are appropriate for my vehicle weight.
Have you got any pictures of your dwarf/legends racing front suspension bits?
TomA
Anyway... When you're talking "fully enclosed design", there are differences in how we all use the vocabulary.
To me "fully enclosed" means that the wheel is completely within the body envelope and only the bottom of tire is visible, like on a Lotus 11 or a 1950s Nash. My trike will probably have front skirts covering the wheels. In order to fully enclose them this way, the body has to be wide enough to accommodate the tires at full steering lock, and you also have to think about brake cooling.
The Mango velomobile pictured in your post has a wheel/tire package that is exposed but basically flush with the outer body envelope when pointing straight ahead. If that's "fully enclosed" to you, fine, just so we understand each other. That's the most logical and practical way to do it, and will give you the narrowest body for a fully fendered design. You might even soften (increase the radius) of the trailing half of this opening, as on the Solectria Sunrise, GM EV-1 and many other cars.
Tandem would give you a an aero length-to-frontal-area-diameter ratio closer to the ideal of 4.5-5:1, but there are a lot of issues involved. If your frontal area is 85% ( a good rule of thumb number) of your 33" height and 55" width, that's about 12 1/2 square feet. The theoretical diameter of that cross-section is right around 4 feet. just rough numbers here, but instructive. Now, 4 and a half times that is 18 feet, almost double your projected length, which suggests your body envelope has more frontal area than is optimal for the aero of your projected length. Your projected length-to-frontal-area-ratio is about 2 1/2:1. If you went with the tandem configuration and exposed the wheels, you might shed 25% of your frontal area. That, combined with the longer length, would increase the ratio to almost 3:1. Still not ideal, but a big improvement. That said, this is a huge oversimplification, and I may be focused on something that is only important to full envelope low-drag vehicles like mine, and almost irrelevant to open wheelers with other aero issues. Eric can chime in here as he sees fit...
The question "aerodynamically, is it better to be wider but fully faired, or thinner but with open wheels?" really depends on many things, including how wide your tires are, how well you can clean up the air moving around the exposed wheels and suspension, (like the Aptera or a Bonneville lakester,) how sleek or bulbous either alternative body style is going to be, especially around the wheel openings versus wheel pants, etc. etc. There is no one obvious answer for every design package, but I would think if your full envelope trike is in danger of having the proportions of a frog and not a tadpole, then a cross-sectionally smaller open wheel design might be a better approach.
Incidentally, so long as these vehicles are going to be electric (under-) powered, I don't see any benefit to wide or low-profile tires. They weigh more, use more energy to roll, create more aero drag, and put more force into the chassis. I will be using motorcycle tires, which are appropriate for my vehicle weight.
Have you got any pictures of your dwarf/legends racing front suspension bits?
TomA
John in CR
100 TW
TomA,
Thanks for that rule of thumb info on frontal area to length ratios. Is that kind of info available in an aerodynamics 101 type text, or something too advanced for someone like myself with 0 formal engineering training, but catches on quick?
John
Thanks for that rule of thumb info on frontal area to length ratios. Is that kind of info available in an aerodynamics 101 type text, or something too advanced for someone like myself with 0 formal engineering training, but catches on quick?
John
todayican2
100 W
- Joined
- Apr 22, 2009
- Messages
- 139
Tom, as always, a pleasure.
At this link is a pretty good view of one of the aftermarket spindles, the part I dont care for much is that the steering knuckle is low and forward, for my design I need high and forward. I spoke to them and they are happy (for a few hundred dollars) to put the steering wherever I want
http://www.peterdmotorsports.com/index.html
At this link, it is a unique design, in that the brake ears are reversable, meaning they can simply be "reversed" putting the steering knuckle forward and high, nice looking too:
http://www.predatorraceproducts.com/servlet/the-288/spindle-hub-cnc-billet/Detail
I appreciate the input on body styles, I have been racking my brain lately on what I want to build, and need to come to a decision soon, as its almost time to start cutting and welding
I have been giving more then a little thought to building a 1 seater based on this design: http://www.blueskydsn.com/ I can get the body, canopy, pan for like 1k and go with a low dollar drive train, I am thinking etek, 60v and a 5hp or 6.5hp turning a second sprocket on the eteks shaft (so the etek can do its thing up to say 40 and the ice can do its thing at higher speeds. If I went this way, I would use spindles and brakes off of a 400ex (aluminum) and use aero section tubing for the arms.
I could probably build this machine for like 6k
Or there is the two seater, tandem, now I am thinking, dwarf car arms, ac-31 motor, 10hp ice, 100ah at 108 volts, probably about 15k to build.
Decisions, decisions lol...
At this link is a pretty good view of one of the aftermarket spindles, the part I dont care for much is that the steering knuckle is low and forward, for my design I need high and forward. I spoke to them and they are happy (for a few hundred dollars) to put the steering wherever I want
http://www.peterdmotorsports.com/index.html
At this link, it is a unique design, in that the brake ears are reversable, meaning they can simply be "reversed" putting the steering knuckle forward and high, nice looking too:
http://www.predatorraceproducts.com/servlet/the-288/spindle-hub-cnc-billet/Detail
I appreciate the input on body styles, I have been racking my brain lately on what I want to build, and need to come to a decision soon, as its almost time to start cutting and welding
I have been giving more then a little thought to building a 1 seater based on this design: http://www.blueskydsn.com/ I can get the body, canopy, pan for like 1k and go with a low dollar drive train, I am thinking etek, 60v and a 5hp or 6.5hp turning a second sprocket on the eteks shaft (so the etek can do its thing up to say 40 and the ice can do its thing at higher speeds. If I went this way, I would use spindles and brakes off of a 400ex (aluminum) and use aero section tubing for the arms.
I could probably build this machine for like 6k
Or there is the two seater, tandem, now I am thinking, dwarf car arms, ac-31 motor, 10hp ice, 100ah at 108 volts, probably about 15k to build.
Decisions, decisions lol...
I don't think the Predator Mod-lite spindle is flippable. The upper ball joint mount is narrower than the lower. The caliper mounts and steering arm are indeed reversible, but it looks like only front to back. Also, the steering arm has no Ackerman angle at all. I don't know how that is handled on these legend cars. Maybe they put so much weight on the outer wheel when sliding around corners (like a modified or sprint car) that it doesn't matter. Still, I like this lightweight piece. Pricey, though, yes? BTW, these legends cars apparently have something of a reputation for not handling very well and requiring quite of bit of setup work. Could be related to that Ackerman thing and the almost equal length arms. That could just as likely be because they are so adjustable and tend to be fielded be less experienced racers, but who knows?
The coolest thing to my eye about these dwarf legends cars is the trick steering rack. That is cool, and probably weighs less than 5 lbs. if I were making a 2-seater that would be on my 'must have' list...
Anyway, I finally received my Suzuki LT250R front suspension. I am completely totally thrilled with it. I know everyone says these ATV parts are crap and such, but my vehicle will weigh less than the donor ATV, and has less power and lower speed to boot. I just don't think I'm going to find them under-engineered for my purposes. I also have regen, reducing the load on the brakes. I was worried before, but now I have these parts in my hands, I'm far less concerned. The Quadracer was fast and tough. My trike needs to be less of both. Maybe the wear parts won't go 20,000 miles, but that's probably 4 or 5 years of service for my vehicle. Whatever, I'm moving forward.
I'm simply delighted with this front suspension set-up. First, the lightness... It only weighs 40 lbs total for both sides fully assembled, including the hubs, rotors, calipers, steering arms, stock springs and shocks, but without brake lines, wheels or tires. That's fantastic. If I replaced everything but the spindles with custom chromoly fabbed parts, it probably wouldn't save more than 5 pounds. I don't need to do that. My (revised) front suspension weight budget is 70 lbs. With a set of Vespa wheels and scooter tires at 21 lbs, and another three for brake lines, I'm going to be comfortably under weight. A lighter set of trick shock/spring units might save a couple or even five more pounds. Nice, nice, nice...
Then, the dimensions. More compact than I had hoped! The units are right about 15" from the centerlines of the chassis mounting bolts on the arms to the wheel mounting flange on the hubs. I think I can narrow my chassis from the stock dimensions so that the centerlines of the chassis bolts are 4" apart. My wheel/tire package will add 2" per side. That's 38" overall width pointing straight ahead. Rough calculations are indicating 43"-44" overall at full lock, which is narrower than I had hoped was possible. I'm now transferring all these dimensions to my 1:3 model drawings for verification and construction. If it fits together as planned, my trike is actually going to be a teardrop, and could be at the ideal frontal-area-diameter-to-length aero proportion in as little as 10 feet of length.
I can't wait to get the model built...
TomA
The coolest thing to my eye about these dwarf legends cars is the trick steering rack. That is cool, and probably weighs less than 5 lbs. if I were making a 2-seater that would be on my 'must have' list...
Anyway, I finally received my Suzuki LT250R front suspension. I am completely totally thrilled with it. I know everyone says these ATV parts are crap and such, but my vehicle will weigh less than the donor ATV, and has less power and lower speed to boot. I just don't think I'm going to find them under-engineered for my purposes. I also have regen, reducing the load on the brakes. I was worried before, but now I have these parts in my hands, I'm far less concerned. The Quadracer was fast and tough. My trike needs to be less of both. Maybe the wear parts won't go 20,000 miles, but that's probably 4 or 5 years of service for my vehicle. Whatever, I'm moving forward.
I'm simply delighted with this front suspension set-up. First, the lightness... It only weighs 40 lbs total for both sides fully assembled, including the hubs, rotors, calipers, steering arms, stock springs and shocks, but without brake lines, wheels or tires. That's fantastic. If I replaced everything but the spindles with custom chromoly fabbed parts, it probably wouldn't save more than 5 pounds. I don't need to do that. My (revised) front suspension weight budget is 70 lbs. With a set of Vespa wheels and scooter tires at 21 lbs, and another three for brake lines, I'm going to be comfortably under weight. A lighter set of trick shock/spring units might save a couple or even five more pounds. Nice, nice, nice...
Then, the dimensions. More compact than I had hoped! The units are right about 15" from the centerlines of the chassis mounting bolts on the arms to the wheel mounting flange on the hubs. I think I can narrow my chassis from the stock dimensions so that the centerlines of the chassis bolts are 4" apart. My wheel/tire package will add 2" per side. That's 38" overall width pointing straight ahead. Rough calculations are indicating 43"-44" overall at full lock, which is narrower than I had hoped was possible. I'm now transferring all these dimensions to my 1:3 model drawings for verification and construction. If it fits together as planned, my trike is actually going to be a teardrop, and could be at the ideal frontal-area-diameter-to-length aero proportion in as little as 10 feet of length.
I can't wait to get the model built...
TomA
John in CR said:
Well, its one of those conventional wisdom things that I just can't put a finger on right now. I don't remember where I discovered this. It was more than one source. I think it actually comes from quite old experimentation with airship (lighter than air craft) streamlining and drag reduction. I just don't know.
Perhaps someone with more training can comment.
What is most interesting is to look at my favorite low drag cars of all time- the Summers Brothers Bonneville cars- and study their proportion- especially the "pollywog" single engine car from 1962:
And, of course the Goldenrod. in plan view, this car has more in common with the Hindenberg than anything else on 4 wheels...
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todayican2
100 W
- Joined
- Apr 22, 2009
- Messages
- 139
Tom A, I dont know the exact science on this, remember I am a "Hey it worked for him!" kind of engineer, But 38" sounds REAL narrow. I happen to know first hand the result of what happens when one goes over.
Tom
TomB:
Agreed. The narrow track and tippiness has been one of my biggest concerns all along.
The front track is actually closer to 34" and I'm toying with the idea of powering the 1:3 model just to see if it rolls over easily.
Keep in mind, though, this is a very small, featherweight vehicle. The narrow track is in proportion to that, and really isn't as small as the dimension would be on a heavier vehicle with wider wheels.
I'm getting a painful education on weight reduction. My trike is designed with a dry (no batteries) weight of 235 lbs. I can say pretty confidently that one can't get there with a tube frame and/or auto parts, and you'd have to be optimizing those metals to a very high level of engineering to make 250lbs. It would have to be a bonded honeycomb aluminum tub, or a tig-welded very small chromoly tube space frame (like a Maserati Tipo 61,) which would actually be sensational- and sensationally expensive. It isn't that composite is going to be all that much lighter than metal, but mostly it will be far stronger for the same weight, and at a fraction of the cost.
But yeah, I worry it will roll over, too. We shall see...
Agreed. The narrow track and tippiness has been one of my biggest concerns all along.
The front track is actually closer to 34" and I'm toying with the idea of powering the 1:3 model just to see if it rolls over easily.
Keep in mind, though, this is a very small, featherweight vehicle. The narrow track is in proportion to that, and really isn't as small as the dimension would be on a heavier vehicle with wider wheels.
I'm getting a painful education on weight reduction. My trike is designed with a dry (no batteries) weight of 235 lbs. I can say pretty confidently that one can't get there with a tube frame and/or auto parts, and you'd have to be optimizing those metals to a very high level of engineering to make 250lbs. It would have to be a bonded honeycomb aluminum tub, or a tig-welded very small chromoly tube space frame (like a Maserati Tipo 61,) which would actually be sensational- and sensationally expensive. It isn't that composite is going to be all that much lighter than metal, but mostly it will be far stronger for the same weight, and at a fraction of the cost.
But yeah, I worry it will roll over, too. We shall see...
todayican2
100 W
- Joined
- Apr 22, 2009
- Messages
- 139
Well, I was just about to start cutting steel on my 2 seat tandem electric / gas hybrid, bought the "peter d" spindles, heims, etc when LOOK, A SQUIRREL lol
I found a 250cc scooter locally that was too darn cheap to pass up, so I took a small detour into 1 seater, atv / quad suspension land.
pictures to follow on tshtrikes.com
Tom
I found a 250cc scooter locally that was too darn cheap to pass up, so I took a small detour into 1 seater, atv / quad suspension land.
pictures to follow on tshtrikes.com
Tom
Very cool pics on the website, Tom.
I love the way y'all tear into these projects and start banging them together. Very inspirational and super valuable for us all to see what you've done and discovered.
I thought you were using 10" tires for the Mini, but I didn't realize they could be mounted on ATV rims. I suppose it varies by manufacturer, but what size rims did you mount them on?
Also, love that aluminum seat you are using! I'll be making my own, with the vehicle essentially being tailored to me. My brother-in-law sent me this way cool link to an audio MP3 of Dennis Wolter (an approx. 57 MB mp3 download), founder of Air Mod, discussing human factors, aesthetics, and safety considerations regarding the interiors of homebuilt aircraft. Its the first item on the EAA Forum Review list here:
http://www.eaa.org/experimenter/forums.asp
The trickiest part seems to be getting the foams he's talking about. I'm not going to bother. For my vehicle, its a little simpler- the seat hard shell is the right shape for me to start with, so I won't need thick padding for support or adjustment. Moreover, the vehicle has less than an hour of range, so it doesn't have to be too supportive, either. Lastly, the trike doesn't vibrate, so the foam I'll be using will probably be 1/2" closed cell gym/yoga mat-type stuff right over my composite tub, which should fit me like the proverbial glove. Simple and light.
I'm working on my 1:3 scale "mini-me" model this afternoon...
TomA
I love the way y'all tear into these projects and start banging them together. Very inspirational and super valuable for us all to see what you've done and discovered.
I thought you were using 10" tires for the Mini, but I didn't realize they could be mounted on ATV rims. I suppose it varies by manufacturer, but what size rims did you mount them on?
Also, love that aluminum seat you are using! I'll be making my own, with the vehicle essentially being tailored to me. My brother-in-law sent me this way cool link to an audio MP3 of Dennis Wolter (an approx. 57 MB mp3 download), founder of Air Mod, discussing human factors, aesthetics, and safety considerations regarding the interiors of homebuilt aircraft. Its the first item on the EAA Forum Review list here:
http://www.eaa.org/experimenter/forums.asp
The trickiest part seems to be getting the foams he's talking about. I'm not going to bother. For my vehicle, its a little simpler- the seat hard shell is the right shape for me to start with, so I won't need thick padding for support or adjustment. Moreover, the vehicle has less than an hour of range, so it doesn't have to be too supportive, either. Lastly, the trike doesn't vibrate, so the foam I'll be using will probably be 1/2" closed cell gym/yoga mat-type stuff right over my composite tub, which should fit me like the proverbial glove. Simple and light.
I'm working on my 1:3 scale "mini-me" model this afternoon...
TomA
jmygann
100 kW
- Joined
- May 30, 2008
- Messages
- 1,069
Looking to build a 2 passenger (side by side) tadpole trike
http://www.progressiveautoxprize.org/teams/tri-hybrid-stealth
http://reversetrike.com/raptor.html
Maybe get a frame /suspension from one of these ....
http://tinyurl.com/mwl5ou
http://www.tangotrikes.com/index.php
http://www.scootcitytours.com/Car.html
http://www.progressiveautoxprize.org/teams/tri-hybrid-stealth
http://reversetrike.com/raptor.html
Maybe get a frame /suspension from one of these ....
http://tinyurl.com/mwl5ou
http://www.tangotrikes.com/index.php
http://www.scootcitytours.com/Car.html
todayican2
100 W
- Joined
- Apr 22, 2009
- Messages
- 139
The tires are dot falkens mounted on plain ol' douglas wheels 5" wide the offset is "4-1" paid $12 a piece for the wheels
The more I think about this little 250, the more I want to drive the thing lol.
especially looking forward to doing some "body, on, body off mpg testing.
The more I think about this little 250, the more I want to drive the thing lol.
especially looking forward to doing some "body, on, body off mpg testing.
jmygann said:
Interesting collection of links there...
The tri-hybrid-stealth mockup is interesting. Like a lot of X-Prize efforts I've seen, its a real challenge for efficiency to have the occupants side by side.
The Raptor on reverse-trike.com is flimsy looking to me. The rear coilovers are mounted to the center span (!) of a simple tubular aluminum crossmember, and there's no triangulation at all for the overhead hoops and tail. I notice the company's website is no longer and the domain not registered. Surely not too many takers for that product at $10k.
The Noyz N Toyz trike is a little strange, too. 583lbs dry, with a total GVWR (if I understand the site information) of 710lbs. That means each occupant has to be under 65 lbs. I obviously don't understand something about this vehicle...
The Scoot and Tango are indeed the best sorted, and look pretty cool. Not sure either of them has reverse, though. Expensive, too.
If you want to build something scooter powered, what Tom & the boys at tshtrikes.com are doing right now is right up your alley...
Good luck, and let us know how its going!
Tom