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Hopkins Baja Design / Build Thread

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jhu42 View Drop Down
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Topic: Hopkins Baja Design / Build Thread
    Posted: 2009-Nov-11 at 12:10am
Hey guys,

So Baja is very interesting in the way that there is a lot of innovation, yet most teams are hesitant to reveal how they do something in fear that they will be copied and beaten with that respective technology.  As a senior this year at Hopkins, I have had a number of lectures on Intellectual Property and Patents.  One of the interesting things about a patent is that it provides a way for an inventor to get credit for their invention, while still revealing it to the public and adding to the overall body of knowledge.  This is why people patent things rather than just keeping them secret, it allows a way of getting credit for an idea.

Before this forum went up there was no way to have a central repository for ideas that were credited to your team.  But!! Now that we have this sweet forum, with the capability of having threads, it is now possible to make a long design/build thread which documents ideas that you had and simultaneously share them with peers.

I think we as a team come up with some pretty cool stuff.  Obviously its nothing earth shattering, but I think that as Baja continues to improve it will be nice to know who came up with an idea first.  A great example of where this did NOT happen is the great TTU vs. ETS wheel covers debate Smile

So with that in mind, this thread will document our design/ build progress.  We pretty much have our car designed, minus some small stuff but it will give you a good idea of the stuff we did and why we did it.  Also once the car begins construction we will be uploading pics of our progress along with text on our methods.  I mean wouldn't it be cool if our car construction methods made it into the Baja vernacular, like bending tubes the "Hopkins" way !! probably not, but its possible.


So with that as an introduction to the Hopkins Baja 2010 Thread, Lets begin.........


Edited by jhu42 - 2009-Nov-12 at 10:50pm
Adam Baumgartner
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 12:42am

So I just wanted to get in a reply in on the car's progress to start the thread off.

Here are some shots as it was about a month ago.  I am not by our CAD workstation, so I don't have the most updated photos.  But anyways, what the chassis does show off is a good use of fewer tubes.  It seemed our moto last year was like Cingular, more bars in more places, but by making nodes for things like the shock mounts we can make a much stronger car with less tubing. 

Another key is that if you look at the side shots of the car the gas and brake pedals are way far forward.  This is because the best option for a spool car is a 50/50 weight distrubition.  If you don't have force on the front tires you will not be able to turn.  We found this out the hard way with our car last year.  We had a weight distrubution of 35, 65.  This was bad, it took us like 3 states to turn.  This new configuration we have below we lifted from ETS, Thanks guys!! , in their 2009 practice video on youtube.  I have attached a picture which shows how far forward their feet are. 





















Picture from ETS Video 
http://www.youtube.com/watch?v=LPHdqXCs7dI











Adam Baumgartner
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Post Options Post Options   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 1:31am
Looks good man.  That's a pretty compact little ride.  We suffered from the same problem that you did in the weight distribution area although ours was slightly better at 36:64 :)  We're taking similar steps to fix the distribution, including shortening the driver area and moving the engine down and forward.

Just a tip from our '07 car, don't use the butt joints for the RRH, make them mitered joints.  If you run them like that you are far more likely to deform the tube in a "crushing" manner.  Our LC in the RHO is like that and after several hard rolls you can see visible deformation in that tube.  True it's easier to make, but in the long run it's my experience that the miter pays off.
-Chris Reedy
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Post Options Post Options   Quote charles ulaval Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 1:36am
Why don't you try to turn things around with a car faster than sherbrooke, lighter than U of Michigan and using something better than carbon fiber? That may be the way you should think... Baja is all about time (so money too!) so if you kick your own ass with a motivated team, I guess you could also win! It may not be this year but you probably can. It's the way you're involved in baja that will make the difference!
by the way, our CAD is not entirely finished so, good job Cool


Edited by charles ulaval - 2009-Nov-11 at 8:36am
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Post Options Post Options   Quote DrewT Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 3:15am
Originally posted by CLReedy21


Just a tip from our '07 car, don't use the butt joints for the RRH, make them mitered joints.  If you run them like that you are far more likely to deform the tube in a "crushing" manner.  
100% agree, the mitered joint is much stronger and less prone to damage; a few tip overs and the top corners of that roll hoop are going to look ugly.  (not to mention getting the tech inspectors all upset and getting you pulled out of the race untill its fixed)
 
 
This thread is an obvious attempt to get us all to give you our most innovative technologies, but I'll bite anyway Wink .  I'd like to apply for a couple Baja SAE forum patents for the WWU Baja team:
 
The first one being the use of mountain bike brakes; let it be known that even though I fully expect Michigan to show up with them this year on a sub-300lb car, WWU has been running them since 2008.  I only assume we are the first in this regard because of the crazy disbeleiving looks we got everytime we pointed them out at comp; if I've accidentally infringed on someone else's Baja forum patent than you have my sincere apology.
 
The second one that comes to mind is our steering-sensitive front cutting brakes.  I really had a good chuckle when the design finals judges at Oregon 2009  made such a big deal about us "bringing brand-new technology to the competition".  It was our third year and second car with the system, and the third iteration of that particular design feature; the judges had never even cared about it the previous 2 years and the only thing really "new" about it was that we figured out how to "sell it" to the judges.  The best part of the story is how the front steering-sensitive cutting brakes came onto the drawing board in the first place:  At South Dakota in 2007, one of our cars blew up a polaris wheel bearing and hub (big surprise) and nearly destroyed the right front upright during endurance.  The car was hastily put back together, but the right front caliper mounts had been destroyed and the rotor was bent;  a command decision was made to zip-tie the caliper inside the footbox and run without a right front brake.  Unfortunately, this tidbit of information didn't get passed on to the driver going into the car.  He came off the track for the next driver change and immediately said, "theres something wrong with the brakes, but when I use them the car turns left awesome."  He hadn't even noticed it was a brake caliper that was dangling around in the footbox getting in the way of his feet.  The next year we had cutting brakes on the front, but this time they were on purpose and worked in both directions.


Edited by DrewT - 2009-Nov-11 at 3:18am
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 5:39am
[QUOTE=DrewT]

This thread is an obvious attempt to get us all to give you our most innovative technologies, but I'll bite anyway Wink .  I'd like to apply for a couple Baja SAE forum patents for the WWU Baja team:
 
[QUOTE=DrewT]


Actually Drew, Thanks, but its not a trick, serious face, I would like to keep it for the Hopkins Baja team.

Again, I'm not trying to get other people to say their ideas, really, I'm just posting for my squad. 

Adam
Adam Baumgartner
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Post Options Post Options   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 6:35am

Have you run your frame through any FEA yet?  I'm asking because this is the first year we are not bringing out RHO down to meet the front of the car.  Instead it stops around where the shock mounts are like many other teams do.  I noticed that you don't have any other front bracing to distribute the forces (like from where the RHO meets the frame forward to the bumper) in a front end impact, which is what my concern is.  If you have run FEA what loads did you apply and what were the results?  Ours isn't 100% drawn yet otherwise I'd give our results to compare. 

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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 9:50am
Adam,

Make sure you cover your feet with frame members. You need to to have something to prevent tire intrusion. Our feet were more covered than that, and they still made us add tubing.
-Joe

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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 5:11pm
Hey,

nice design, here is a little snap pic of ours and i cant help see the similarities! We are also reducing number of tubes and their respective thicknesses. My main design point this year is ease of fabrication, for example, we will machine two holes+insert in the bottom rear members in the frame before welding to mount the gearbox, less welding, less jigging,  this just requires a little foresight.
http://minibaja.mcgill.ca/?page_id=92


Edited by jeiB - 2009-Nov-11 at 5:55pm
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-11 at 7:21pm
Hey Adam,

I was looking through ur pictures. Did you redesign the rear suspension of your baja between alabama and wisconsin or did you bring another car?
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 7:45am
Hey JeiB,

Yeah, we rebuilt the rear of the car.  It was not fun, but the car did turn a whole lot better with the improved weight distrubution.  but at that length we started to have problems with the length of the car limiting the turning cicrle.  I was looking through the Alabama competition car data sheets ( Horray for data mining) and found that there is a grey area for successful car's wheel base,  seeems about 65" is the upper limit and it goes down to 62"  or so.  I think being in that range for wheel base and having as close as possible to a 50/50 weight distrubution is the key to having a car that turns well. 


Oh also RobZilla, we do not have fea on that yet, but we're not going to hit any trees.  The competition is usually designed with that in mind.  I have the philosophy that if the rules don't say to have a tube, then not to have one.  But thats just me.


Adam Baumgartner
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Post Options Post Options   Quote johnpate01 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 9:25am

That's a pretty neat design overall.  I like it, especially making the front main node into a shock mount.  

I do have one warning, though.  The tech inspectors will probably bust you on your brake master cylinders being unprotected (outside of the frame tubes).  They got us at Auburn for our brake light.  Just my thoughts though.

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Post Options Post Options   Quote Old Greg Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 12:30pm
Originally posted by jhu42

... there is a grey area for successful car's wheel base,  seeems about 65" is the upper limit and it goes down to 62"  or so.


I disagree.

Land Mo:
1) 60" (RIT)
2) 66.5" (USF)
3) 62" (Louisville)
4) 60" (UMCP)
5) 59" (Auburn)
6) 60" (U. Mich)
7) 62" (Queens)
8) 57" (ETS)
9) 61.5" (Northeastern)
10) 70.5" (TTU)

S&T:
1) 60" (RIT)
2) 60" (UMCP)
3) 70.5" (TTU)
4) 59" (Auburn)
5) 57" (ETS)
6) 62" (Louisville)
7) 66.5" (USF)
8) 61.5 (UMBC)
9) 60" (Sherbrooke)
10) 61.5" (Northeastern)

Endurance:
1) 61.5" (Sherbrooke)
2) 57" (ETS)
3) 67" (Michigan Tech)
4) 60" (UMCP)
5) 62" (Louisville)
6) 60" (RIT)
7) 70.5" (TTU)
8) 63" (Kansas State)
9) 58.5" (Fairmont State)
10) 68.5" (Pittsburgh State)

It seems to me that all the successful cars happen to be 62" or less, with the notable exceptions of Mich. Tech, TTU, Pittsburgh State and USF (all over 65"). Which to me proves absolutely nothing except that wheelbase isn't really a big deal until the numbers start getting crazy.  I mean, if TTU can whoop up on 78 other teams on a tight twisty Land-Mo course in a car with a 70.5" wheelbase, then there are much more important factors at play.

But yeah, weight distribution FTW.


Edited by Old Greg - 2009-Nov-12 at 11:00pm
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Post Options Post Options   Quote Waffles Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 1:33pm
high CG + stiff sway arm = power induced oversteer

Is USF's lower CG offset by a direct drive in terms of getting the rear wheels to swing out under power?
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Post Options Post Options   Quote DrewT Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 2:55pm
I'd also disagree with the criteria of wheelbase and weight distribution being the most important factors to a car's success in maneuverability.  Our last car had a 66" wheelbase and a 40/60 weight distribution, one of the lowest CG's you'll see in Baja, and a spooled rearend.  It was 3rd in maneuverability at Illinois and 17th in maneuverability at Oregon.  The biggest factors I see are the suitability of your vehicle to the particular course (it changes every year), and the skill of the driver.  Close behind those would be the simple performance of the car in acceleration and speed (getting from corner to corner faster is a big deal).  Our last car broke all those generic rules about the wheelbase, trackwidth, weight distribution, ect., but is a really nice handling car because the overall package is tuned to work together.  The anti-roll bar lifts the inside rear, the front cutting brakes provide a little extra turn initiation to get the power-on oversteer to happen, and the very soft but well-balanced suspension allows the driver to manipulate the car with all sorts of weight transfer tricks, and the low CG means the car can do all of that stuff, even when the course is off-camber, without having to slow down or risk rolling.
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Post Options Post Options   Quote Old Greg Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 8:45pm
Originally posted by Waffles


Is USF's lower CG offset by a direct drive in terms of getting the rear wheels to swing out under power?


I'm not sure if I understand what you're asking.  Are you referring to the spool?  Since I doubt you mean our super-awesome Lovejoy coupler, I'm just going to assume so.

In theory, a spool is actually going to cause understeer; Since the rear wheels are locked together, they'd really rather keep traveling in a straight line.  Oversteer is all about weight transfer.  Whether you're getting it from a high CG, high roll stiffness or even a bit of both, what matters is that you're picking weight up off the inside tire and putting it on the outside tire.  The sum of the vertical forces at the contact patches is the same, but the total grip is reduced because tires are funny that way.  Hey Presto: Slide.

Case in point:  Our 2008/9 car has sprung a leak in it's fancy pneumatic anti roll system (tm) and no longer has any rear roll stiffness save that provided by the springs/suspension geometry.  Since it has a spool, IRS, and a fairly low CG it is, well, let's call it 'stable'.  The rear end stays planted at all times, and just seems to follow you around like a lost puppy.

Our swing-arm cars, on the other hand are effectively spooled and probably have even lower CGs.  Yet they oversteer at the drop of a hat.  The difference comes from the fact that the swingarm cars have stupid high rear roll stiffness, and subsequently a lot less of that pesky traction stuff.
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Post Options Post Options   Quote USF Stick Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 9:24pm
Originally posted by jhu42


Cornell's car will always have more carbon fiber
Did you see USF's car last year? We had carbon composite RIMS!!!


Build progress, will be up as soon as I can get the pics I have resized, and put on our website. Basically in a week we went from nothing to RRH and forward tacked in and in place.

The frame should come off the table and burned in this weekend.

If your wanna see the current progress www.usfracing.com click on Who's in the Shop > Fabrication Shop Cam


Edited by USF Stick - 2009-Nov-12 at 9:24pm
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 9:26pm
Hey Greg,

Man, thanks for the correction.  62" does seem like a much better wheel base to shoot for.  I dont understand though why you say that this proves nothing ?  A sizeable number of successful teams have that wheel base.  Of course most baja cars look like that anyways, unless you try to do something stupid like we did with our 2009 car, lol, 54"  wheel baseThumbs Down with 35, 65 distriubution. 

I guess more what I am trying to say is that there are no "improvements" that come from going outside of the 62" design envelope, which is what we thought we could acheive with the 2009 car.

I do feel that wheel base is critical. 

I guess a better way I look at it is to say do you make your car better when you put more weight on the rear?

 But now we know that the more weight we can get on the front of the car, the better it will turn. 

Oh and also that if its lighter, it goes faster Cool !!!!


Drew, though, your right also in saying that a good total car system beats a good "in theory" car any day.  I was just noting that weight distrubution was something we had not given enough thought to and need to work more at.

Glad to hear you had the cutting brakes idea!!!  I was thinking about a similar system for our car this year Tongue .  And was wondering if anybody had ran it, it seemed like such a good idea.  Love the story!!  But I cut the plans for this year in favor of the Okham's Razor vehicle


Adam Baumgartner
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 9:28pm
Originally posted by USF Stick

Originally posted by jhu42


Cornell's car will always have more carbon fiber
Did you see USF's car last year? We had carbon composite RIMS!!!



Dang!!!

Hey Stick!!

Can't believe I forget the coolest team that's better than us :)

CF Rims! How are we supposed to compete with that, lol. 

And you have a Bus!!  Oh well, 5th place is not so bad!!


Adam Baumgartner
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 9:32pm
More importantly, live webcams in the shops. You guys are ridiculous. Thumbs Up
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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 10:14pm
Originally posted by Old Greg


Endurance:
1) 61.5" (Sherbrooke)
2) 57" (ETS)
3) 67" (Michigan Tech)
4) 60" (UMCP)
5) 62" (Louisville)
6) 60" (RIT)
7) 70.5" (TTU)
8) 63" (Kansas State)
9) 58.5" (Fairmont State)
10) 68.5" (Pittsburgh State)

Corrected.  If this data is going to be used you have to make sure it's organized right.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 10:33pm
Oh and I updated our photos,
Complete Hopkins baja Photo history, USF/Picasa
http://picasaweb.google.com/jhubaja
Adam Baumgartner
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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 10:33pm
Originally posted by jhu42


There are of course going to be some that think this is a bad idea.  That's ok.  "Adam, your giving away your team's secrets!! "  Well, here are the facts, We're never going to win Baja.  Michigan's car will always be lighter, Cornell's car will always have more carbon fiber, and Sherbrooke's car will always be faster.  So at best I finish in 4th place, lol, just kidding.  However, even though my team will never win, I can get my team recognized by my baja peers for the innovation we have worked on.


What a horrible attitude!  I honestly believe everyone on my team believes that we can and will one day win a (sanctioned) Baja event.  It may not be while I'm on the team, but I'm very proud of the progress that we have made and will be greatly disappointed if the guys that take over after our current vets are gone have the mentality that they will never win.

Adam, don't get star struck by the ETSs, Cornells, Sherbrookes.  Sure, maybe they were lighter, faster, or just more competitive than you but who says it has to be that way forever?  Why can't you take them down and be one of them?

I can remember conversations where past Baja guys from our team asked how a certain team did because "They used to be good."  If they "used to be good", didn't someone have to take their place? ;)


Edited by dillon_b12 - 2009-Nov-12 at 10:40pm
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 10:51pm
Dillon,

You're completely right, I was wrong.  That's a pretty dumb thing to say.

We're in it to win.

Love the quote

" If they "used to be good", didn't someone have to take their place? ;)"




Edited by jhu42 - 2009-Nov-12 at 10:53pm
Adam Baumgartner
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Post Options Post Options   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 11:00pm
Originally posted by USF Stick

Originally posted by jhu42


Cornell's car will always have more carbon fiber
Did you see USF's car last year? We had carbon composite RIMS!!!


Build progress, will be up as soon as I can get the pics I have resized, and put on our website. Basically in a week we went from nothing to RRH and forward tacked in and in place.

The frame should come off the table and burned in this weekend.

If your wanna see the current progress www.usfracing.com click on Who's in the Shop > Fabrication Shop Cam


Carbon composite rims FTMFW. We used the same thing on last years car and will be transferring them to this car too.

If you want to do some of the cool stuff, try to get helpful sponsor(s), we're looking at the possibility of doing a 3 piece steel/CF axle this year.
-Bob
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Post Options Post Options   Quote Old Greg Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-12 at 11:35pm
My sincere apologies to the Louisville guys, I was going by the results spreadsheet from sae.org, and that's the way Excel sorted it.

Adam, all I mean is that correlation is not causation.  62 inches may be the end all, be all of wheelbases, I don't know.  But don't mistake the fact that a lot of fast cars are in that ball park with the idea that it was their wheelbases that made them fast.  You can be fast with a long car and you can be fast with a short car; ETS and TTU are both prime examples of this.  Don't get me wrong though 62" is a fine number to shoot for, but it isn't the only (or even necessarily the best) way to go.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 8:35am
Originally posted by Old Greg



Adam, all I mean is that correlation is not causation.  62 inches may be the end all, be all of wheelbases, I don't know.  But don't mistake the fact that a lot of fast cars are in that ball park with the idea that it was their wheelbases that made them fast.


Right, there are other things at play that make the fast cars fast, of course.

CVT tuning, Weight, Driver skill.

I understand what your saying.

 


Adam Baumgartner
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Post Options Post Options   Quote Waffles Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 9:45am
Originally posted by Old Greg


...
Our swing-arm cars, on the other hand are effectively spooled and probably have even lower CGs.  Yet they oversteer at the drop of a hat.  The difference comes from the fact that the swingarm cars have stupid high rear roll stiffness, and subsequently a lot less of that pesky traction stuff.


Was making the point that TTU has a swing-arm, and high CG - you have a swing-arm and low CG...  Now I'm sure that there is a difference in stiffness of your arms, but I would have thought that given the same swing-arm stiffness, that the low CG car would have a more difficult time going into oversteer.  As such, I was thinking that with a direct drive system, it would be easier to get the rear tires to spin - I was thinking similar to my manual tranny truck, I can't just break the rear tires loose at will, but if i put slack in the drivetrain and then floor it, it's enough of a transient that the rear tires break the static friction and begin to spin.

I suppose I'm just making stuff up, lol, it was just a far off theory given two very different cars with IFS+swingarm, yet both equally maneuverable.
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Post Options Post Options   Quote OctoberSky Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 11:18am
Again it is all speculation, but assumingTTU and USF used the same swingarm setup,   had the same weight, same tires, etc., with a higher cg TTU would probably oversteer more IMO than USF in terms of actual inches of lateral slide in a turn, but because of TTU's longer wheelbase, the measured "degrees of oversteer" would be about the same. Further proof (speculation) that you can reach the same end result in a variety of ways.
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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 11:43am
What's the obsession with carbon composite rims?  From what I've heard from sport ATV guys, they leak, aren't as light as Douglas(depending on label), and cost about 3x more than Douglas.
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Post Options Post Options   Quote Dax Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 12:47pm
The big thing with composite rims it they are able to deflect elastically, and then return to their original shape, and thus not bend and cause the bead to break and loose air. They also typically come with bead locks to keep the wheel on the rim at low tire pressures and when 'flat'
We are looking into them right now, but are still trying to determine if it is worth it. Any other teams have experience with either composite rims, or even just a bead lock aluminum rim? 
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Post Options Post Options   Quote Waffles Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 1:13pm
BTW, I think we have successfully derailed the "Hopkins Baja Design / Build Thread", we should probably stop some of these side discussions!
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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 1:27pm
Agreed. Someone can start a new thread about carbon composite rims if they want to continure discussing it.
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Post Options Post Options   Quote Old Greg Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-13 at 4:15pm
Originally posted by Waffles



Was making the point that TTU has a swing-arm, and high CG - you have a swing-arm and low CG...


Don't forget that TTU's swingarm cars had more rearward weight bias than ours and ran massive rear tires, where we ran 21x7's.  In the end they're likely quite similar.  If you'd really like to know how they compare, ask Chris Reedy from TTU (CLReedy21); If I'm not mistaken, we let him take a few laps of Auburn in one of our old cars at the 2008 invitational.
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Post Options Post Options   Quote USF Stick Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Nov-17 at 10:52pm
Originally posted by dillon_b12

What's the obsession with carbon composite rims?  From what I've heard from sport ATV guys, they leak, aren't as light as Douglas(depending on label), and cost about 3x more than Douglas.


The main cons of the rims are Cost and Weight, but the big pro is the durability.

Last year, across all 3 races we changed ONE tire. A sharp rock pierced the tire sidewall within the last hour at Wisconsin.  That includes hitting the railroad ties in Auburn at full boar EVERY LAP.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-09 at 5:14pm

Bringing the thread back ;)

 

Sort of a teaser, but here's the improved frame side view. 

 

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Post Options Post Options   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-09 at 5:19pm
More pics dammit!
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Post Options Post Options   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-09 at 5:26pm
what is your wheelbase on this car?
are you going to the seat yourself?

AND MOAR pics...Thumbs Up
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Post Options Post Options   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-09 at 5:34pm

-Joe

Ohio State Baja SAE 2005-2009
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Post Options Post Options   Quote blue2kss Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-09 at 9:25pm
How tall of a tire are you running?
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Post Options Post Options   Quote charles ulaval Quote  Post ReplyReply Direct Link To This Post Posted: 2009-Dec-10 at 1:06am
looks like you don't have the 12" required that extends from the lowest point of the seat to the upper LC on the RHO.
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Post Options Post Options   Quote BenPoulin Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-08 at 10:07pm
Originally posted by jhu42


Sherbrooke's car will always be faster. 
 
 
I like that quote...
 
But for the '' We will never win baja'' as long as you learn from your mistakes and that you document your stuff enough so that futur team members can build from your work you'll have a few steps ahead of a lot of the other teams...
 
Hi everyone, just to introduce myself I'm Ben and I was Sherbrooke's Driver in 2005, 2006 and 2007.
 
Salut Charles!
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-09 at 2:33am
Hi guys!

I dont have more pics of the car :( sorry, because we are still finalizing stuff like the suspension and steering.  However, when its done I'll upload the SW model for you to check out.

Answers to the questions from before.

Wheelbase is -> arg! I forgot, will check tomorrow
Seat is the Jegs Highback Pro II with the seat cover
http://www.jegs.com/p/JEGS/JEGS-Pro-High-Back-II-Race-Seats-and-Seat-Covers/1118147/10002/-1
Really cheap seat that is quite comfy!  Really low for the cost report.

tire size: fronts 22x7 Holeshot XC , rears 22x8 Mudlite AT

Charles ->  Good catch!!  I see what your saying!  Thanks for the note.  I will make sure to change that :)



Ok!!

We started construction back on Jan 3, and have just finished day 5.  Hopkins has a nice Intersession period.  Class for us starts back up again on Jan 21, which gives us a lot of time to work on the car

Putting in some long days but its paying off, we are moving ahead quite rapidly with car construction.

Below are some pics along with some captions of how our construction works.





Here's our setup for jigs.

We use a smooth pressed cardboard with high quality wooden blocks.  Pretty simple.  This is our RRH being constructed and assembled before being welded.





Here was our main step today.  One of our guys had the idea to use ratchet straps to hold the notched frame pieces together for tack-ing.  He saw it on the USF website, thanks guys! 

I guess I should mention that we do our tacking with a small portable MIG welder in our labspace, but do the actual welding in our Welding room with a really nice TIG.  I think its a great combo, the trigger style of the MIG makes it really easy to get a lot of tacks down vs trying to balance a foot pedal for tacking with a TIG.




Here's where we are at so far.  Lots to go for sure, but hey, its progress.

Cool, ok well I need to get some rest....

Catch you guys later,
Adam
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Post Options Post Options   Quote msctgb Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-09 at 4:39pm
Looks awesome, love the SIM bends.

Did you change some tube diameters from the CAD model to the real deal?  Looks like you stepped a lot of the 1" up to 1.25", looks great.
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Post Options Post Options   Quote Redhawk_Racing Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-10 at 3:11pm
Looks great so far!  We use the method to jig the frame of the car.  Same tube bender too!

We started fab work this Monday and here is our progress thus far:




Edited by Redhawk_Racing - 2010-Jan-10 at 3:14pm
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-10 at 10:10pm
That's a pretty sweet chassis.

 We've always avoided three dimensional bends, but it appears that you can do them very well !!!






Adam Baumgartner
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Post Options Post Options   Quote msctgb Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-11 at 1:56pm
We use a plane of bend bracket for 3D bends, very simple (I made our team's) to make and use.  http://www.offroadfabnet.com/forums/showthread.php?t=924

Helps for 3D bends, and we also use it to make sure we have notches on either end of a long tube in the exact same plane.  Or if notches need to be in specifically different planes, whatever.  Way better to just turn the tube a known amount than to tilt the head of the mill.
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Post Options Post Options   Quote Redhawk_Racing Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-11 at 2:20pm
The 3D bends aren't too hard.  You just have to take your time and measure the angles very accurately. 

Try it with a couple scrap pieces and you'll get the hang of it.  Our rear bends took about three tries to get perfect, but the floor we got on the first try.
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Post Options Post Options   Quote jhu42 Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-25 at 3:53pm
Hi guys,
 
Well, classes have finally started at JHU :(, but we got a ton of work accomplished.  Here are some photos from the different stages over the last 2 weeks.
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 


Edited by jhu42 - 2010-Jan-25 at 3:53pm
Adam Baumgartner
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Post Options Post Options   Quote EAD Motorsports Quote  Post ReplyReply Direct Link To This Post Posted: 2010-Jan-25 at 5:40pm

I've gone and forgotten frame basics. Is there a reason not to put the front bracing on the bend? The picture might be deceiving, but it looks like the front bracing member is a long way from point C.

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