Official Baja SAE Forums Homepage
Forum Home Forum Home > General > Design Discussion
  New Posts New Posts RSS Feed - The great water event debate
  FAQ FAQ  Forum Search   Events   Register Register  Login Login

The great water event debate

 Post Reply Post Reply Page  123>
Author
Message
rjwoods77 View Drop Down
Milling Master
Milling Master


Joined: Jul/05/2009
Status: Offline
Points: 65
Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Topic: The great water event debate
    Posted: Jul/29/2009 at 1:36am
Hello all,

I figured a great new post to start would be one devoted to all the engineering behind making a car capable of the east event. I figured we could break it down into three different areas of conversation in order to keep it relatively organized even though the system as a whole needs to work in concert with each other. I'll kick it off.

Tires:

It seems the 26x12-12 Carlisle Tru Power is the best tire to use out there assuming equal thruster design. The results of the old water manuv. events are hard to connect with who used what so on and so forth. Input on a suitable replacement that offers close to the same performance but with less weight and size would be appreciated. Carlisle AT101 in 21x11-10 for example.

Thrusters:

Flotation:

Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 2:45am
Tires:  Chevron pattern.  Carlisle Tru Power AT is available in several sizes.  We ran the 26's 06-08 and scored 3 1st's and a 2nd with them in the water.  We're going to be running a smaller size this year on the independent car, not decided which yet.  The main reason for the 26" tire was the ground clearance for the axle in the swingarm.  Knobbies (i.e. Holeshots) will not do crap in the water for propulsion.

Thrusters:  Chevron tires under a fender.  The fender directs flow and keep the rooster tail down.  Make sure they are mounted well.  Plan on being able to stand on the fenders, and then they'll make it halfway through the race... maybe. I've never heard of a successful propeller design on a baja.  Doesn't mean it doens't exist, but I've never seen it pulled off.

Floatation:  For flotation we've always made a "surfboard" out of low density closed cell foam with a little bit of structural material in the middle to allow mounting to the frame.  We have it rhino lined for durability.

Here's a picture of the 2007 car in it's native habitat.  The '08 is a little better but thanks to a hard drive crash I don't have a single picture of it with its water wings on.  2008 is our fastest water car and it tops out at a blistering 6 mph in the water.  Thumbs Up


-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 8:50am
So after seeing what sucessful teams do in the water, here is what NOT to do... well that is if you want to be fast.
 
Tires: 24" ITP Mudlites (backwards of course)  These actually worked out ok, they're reasonably light, move some water, and do pretty well on land.  We had tried some tires similar to the Carlisles, but considering the weight of the rest of our car, we couldn't commit the extra weight to tires, since the car wasn't fast in the water anyways.
 
Thrusters:  Generic shaped fenders somewhat close to the tires... that's the basic premise anyays.  It's all about execution though.  DON'T make them out of fiberglass and attach them poorly, or the WILL fall off... repeatedly.  Fiberglass doesn't like to keep holes very well over baja terrain...
 
Floatation:  If you want to be light, DON'T use open cell styrofoam wrapped in fiberglass... it's heavy, a pain to make, nasty, itchy, etc.  And don't plan on drilling through and attaching the chunk with allthread to the frame... because no matter how big your washers are, they're gonna try to rip out. 
 
 
^^^ All from experience.  Luckily since we didnt have to float at Auburn, we had a whole off year to come up with more viable, and better solutions to this...
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
JHrdy724 View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Oct/24/2008
Location: AUburn
Status: Offline
Points: 37
Post Options Post Options   Thanks (0) Thanks(0)   Quote JHrdy724 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 11:44am
08: 22x8 Kenda BearKlaws, Plastic Thermo-formed Fenders, closed cell foam float wrapped in carbon fiber  - good for 13th if i remember correctly.
07: 26x12 Chevron pattern run reversed. closed cell foam float w/ plastic skid pan -good for 11th

between 07 and 08 we lost 2 places in water maneuverability and we got to drive the rest of the events with the small lighter tires that we like driving on and handle better.
There are three easy ways of losing money - racing is the quickest, women the most pleasant, and farming the most certain.
Lord Amherst
Back to Top
dillon_b12 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/15/2008
Status: Offline
Points: 781
Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 1:13pm
Originally posted by collinskl1 collinskl1 wrote:

So after seeing what sucessful teams do in the water, here is what NOT to do... well that is if you want to be fast.
 
Tires: 24" ITP Mudlites (backwards of course)  These actually worked out ok, they're reasonably light, move some water, and do pretty well on land.  We had tried some tires similar to the Carlisles, but considering the weight of the rest of our car, we couldn't commit the extra weight to tires, since the car wasn't fast in the water anyways.

Floatation:  If you want to be light, DON'T use open cell styrofoam wrapped in fiberglass... it's heavy, a pain to make, nasty, itchy, etc.  And don't plan on drilling through and attaching the chunk with allthread to the frame... because no matter how big your washers are, they're gonna try to rip out. 
 


We have never been to a water competition but did have the '06 car water ready before Ocala in '07.

From experimenting with that car, I completely agree about not using styrofoam.  We covered ours in some stuff called Armorstone that was supposed to be this tough ass coating.  Well it only got tough when it was about .5" thick.  We never even got it to get that thick on the foam but even with the thinnish layer we got on, it was heavy as hell.  I'm wanting to say it added something like 40lbs to the foam.

Also, with the exception of Ocala '07, I don't think reversing tires helps you as much as it hurts you.  Had it not rained in Ocala, reversed tires probably would have been nice since the water stretch was soooo long, but since it DID rain you had a bunch of people barely getting off the starting line because their tires were so clogged with mud.  If water sections are as short as say Auburns, I don't see it as advantageous to sacrifice your tires dry land performance for just a few feet of water.

I don't have any experience with it but I'm not so sure reversed Mudlites would work better than regular anyway.  The "M" shaped tread of the Mudlite seems like the water would roll off the convex peaks while reversed.  Running non-reversed it seems like the water would be moved better by the inside or concave sides of the peaks.  Think of it like stirring something with the back of a spoon.






Edited by dillon_b12 - Jul/29/2009 at 1:25pm
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 1:25pm
We did some testing on which way to mount the tires and having them reversed gave slightly more power than normal, when paired with the right proximity of the fender with relation to the tire... we used one of those spring type scales attached to a tow strap from the rear tow point to the hitch of a truck... not super scientific, but it worked. 
 
I know some teams use flaps inside the fenders that stop/regulate the flow on either side while turning... I'm curious how they actuate these.  It seems to me that those would be a mess to deal with constructing, not to mention placement in the cockpit.  It would be cool to have an electronic system that actuated them based on steering wheel input, but otherwise I envision a tangled mess of strings and bars like a puppet...
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
dillon_b12 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/15/2008
Status: Offline
Points: 781
Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 1:28pm
Well an actual test is more scientific than me just guessing lol.  Have you done much dry land testing with them reversed?
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 1:49pm

Well... we ran TTU in '08 with them reversed on a track that was effectively soup, haha.  When we weren't in the pits cursing our key failure problems we were trucking past people all day long.  They didn't clean themselves as much as they would have forward, but they pulled through everything.  As far as dry testing, we've driven with them both ways, played around with air pressures, both around campus, random farms, Auburn last fall, etc.  We don't have any real way to get data on this stuff, but me and the other driver have fairly well tuned seat of the pants feelings.  Depending on how loose the terrain is/gets it's a toss up.  We ran Auburn '09 with them forward, with no complaints.  Obviously they run better forward over typical terrain, I'm just not sure quantitatively how much so.

Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
rjwoods77 View Drop Down
Milling Master
Milling Master


Joined: Jul/05/2009
Status: Offline
Points: 65
Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 2:48pm
I noticed TTU seems to be the only team out there that runs dampers on their side flotation. Is there a hinge as well or is that for float deflection on impacts.
Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 4:16pm
Just foam deflection on impact.  There is a steel skid inside the foam that it attaches to.
-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
zehlerdj View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Nov/23/2008
Location: Clarkson
Status: Offline
Points: 34
Post Options Post Options   Thanks (0) Thanks(0)   Quote zehlerdj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 7:52pm
Tires: We've ran the 26"ers like TTU in the past in Goodyear and Carlisle. In 08 we ran the AT101's i think you were talking about above in 24", all reversed. A tie for 1st i believe and a 2nd with the 26's and a 7th with the 24s in the water.

Thrusters: Fender tucked as tight as possible to the tire. Molded thermo plastic mounted to the a-arms with some 065 and they won't move for the endurance. We've done a lot of wave tank testing(minus the waves) on optimal fender depth as well as amount of water the tire should take on.

Float: Closed cell foam inside a fiberglass body. Best way we've found due to differing cars year to year is build it big and test, shave, test, shave, test until you get your car sitting right in the water.

Dillon you talked about reversed tires in Alabama being a bad sacrifice from handling on the track but Back in 06 TTU and us, Clarkson, finished 1,2 overall both cars running 26" reversed chevron patterns I believe. so it may be worth the sacrifice

Edited by zehlerdj - Jul/29/2009 at 7:54pm
Dan Z.
Clarkson Baja
Team Leader
Back to Top
rjwoods77 View Drop Down
Milling Master
Milling Master


Joined: Jul/05/2009
Status: Offline
Points: 65
Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 8:40pm
http://www.carlisletire.com/products/big_biters/at101chevron/index.html

Do you think the squarish shoulder of the Tru Powers is the difference in thrust or is the diameter. Also do you think there is a benefit to running a higher top speed in the water to get the tire moving more water? Is there a certain point where you are just making bubbles and not forward thrust when moving the tire rpm fast? I am assuming the cvt shift to the highest ration possible due to limited torque at the contact patch.
Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/29/2009 at 11:24pm
Not sure on the transition between thrust and bubbles, but you are definitely topping out the drivetrain in the water.  I recommend the Tru Power AT over the standard tru power.  Much lighter and the same/95% similar tread.
-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
rjwoods77 View Drop Down
Milling Master
Milling Master


Joined: Jul/05/2009
Status: Offline
Points: 65
Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 1:49am
Chris,

More to the point is this. If you could have a separate gear in you gear reduction that allowed for a top speed of say 60mph, would that allow you to move more water to go quicker or will you simply cavitate the hell out of the water?

Also the 26x12-12 that you guys have run are these?

http://www.titantires.com/titan_tru_power.htm

You mentioned earlier that you had large diameter tires in order to have more swingarm axle clearance. Is this due to mounting floatation on the swingarm under the axle?

Has anyone run a non-offset chevron tire to any good effect. Argo type tires.

http://www.ustractorpulling.com/tractor_pulling_tires.html

Has anyone run a 4-snow like tire with good results

http://tiresunlimited.com/ALL%20TIRES/Maxxis/maxxis_4snow.htm


Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 4:23am
No, TTU has not has multiple gear ratios since 2005, and that was not a water car.  Our theoretical top speed with the swingarm cars has traditionally been just shy of 30.  I have no idea if a super tall gear would help, I assume it would, but I doubt it would make much of a difference at competition.  I don't expect any 1000' water stretches and WaterMo is only a 60/75 point event so an extra gear is really not worth the extra complexity/cost/time in my book.

Yes, the 4-ply 26x12-12 Tru Power AT'sare what we run.

No, it is simply to keep the sprocket, brake rotor, and actual axle off rocks, stumps, etc.  We even run the "Terras" as we call them at midwest events because our car actually likes them alot and handles really well with them.  The yellow car I posted up top came in 3rd at RIT last time sporting the Terras.  They work great for muddy sections, pulls, and hillclimb events too.


-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
zehlerdj View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Nov/23/2008
Location: Clarkson
Status: Offline
Points: 34
Post Options Post Options   Thanks (0) Thanks(0)   Quote zehlerdj Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 8:07am
RJ- We had a two speed hi-lo-nuetral at Ocala in 07 and we actually lost a gear at one point because our driver was shifting in the water. If you don't use a manual tranny like USF with your super tall gear it probably won't work because there is no resistance against the tires in the water so the engine doesn't like to get down to a low enough RPM to shift, thats what happened to us anyway. As well you will never have the power to get out of the water with that gear so your gonna have to be able to shift if your going that route. Just my experiences though.

I don't know if anyone has seen our grill either but we have huge outlaw tires on that which were bought 3 or 4 years ago for water in hopes they could be shaven. They actually had so much propulsion in the water they would pull the back end under water, that would be a bad route to go.

Edited by zehlerdj - Jul/30/2009 at 8:10am
Dan Z.
Clarkson Baja
Team Leader
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 10:34am
Originally posted by zehlerdj zehlerdj wrote:


I don't know if anyone has seen our grill either but we have huge outlaw tires on that which were bought 3 or 4 years ago for water in hopes they could be shaven. They actually had so much propulsion in the water they would pull the back end under water, that would be a bad route to go.
 
Bad Route?  Aww come on, Hummer's sink and drive on the bottom... Just get an extra long snorkle (driver and engine) and waterproof everything!
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
Rob71zilla View Drop Down
Welding Master
Welding Master
Avatar

Joined: Feb/09/2009
Location: Utica, NY
Status: Offline
Points: 324
Post Options Post Options   Thanks (0) Thanks(0)   Quote Rob71zilla Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 11:22am
Have fun pulling that firewall through the water haha
Robbie
Former Team Captain
SUNY Institute of Technology
Current Engineer for Remington Arms

A Redline a day keeps the carbon away.
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Jul/30/2009 at 11:31am

^^ erroneous! 

Do y'all account for weight additions like mud throughout the race when designing the floatation?  I was trying to come up with a figure for how much mud the car picked up in a race...  both of the last 2 east races have been particularly soggy.  What do y'all think, 50#, 75#? more? less?
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
Bi-Brow View Drop Down
Welding Master
Welding Master
Avatar

Joined: Apr/05/2009
Location: Batesville, IN
Status: Offline
Points: 102
Post Options Post Options   Thanks (0) Thanks(0)   Quote Bi-Brow Quote  Post ReplyReply Direct Link To This Post Posted: Aug/04/2009 at 3:10pm
If only we had our flotation ready to go...
 
Cummins XPI Pump Development Engineer
2012 Midnight Mayhem Coordinator
2008-2010 UofL Baja Captain
2011 Powertrain
Back to Top
collinskl1 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jan/21/2009
Location: Saginaw, MI
Status: Offline
Points: 1056
Post Options Post Options   Thanks (0) Thanks(0)   Quote collinskl1 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/04/2009 at 6:02pm
not that there's anything cool about flooding... but that would have been BA to just go hauling through there with no worries about water/land/debris.  Brings the testing to you!  I'm thinking about digging a pit or building a tank behind our shop so we don't have to drive to a lake.
Kyle Collins
Lipscomb University Alumni
2x Project Manager

Nexteer Automotive
Product Engineer, Electronic Power Steering

... and the 8th simple machine: a bigger hammer.
Back to Top
dillon_b12 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/15/2008
Status: Offline
Points: 781
Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/04/2009 at 7:04pm
Update:  Our car is water worthy.  We went on a short adventure through some of the flood water before campus police pulled us over.  He was kind of mad at first until I explained and then he smiled and asked "Well, does it float?"

That second to last shot in that series of photos is our shop.

For anyone who is wondering, Louisville got around 6" of rain in a 1 hour time frame today.


Edited by dillon_b12 - Aug/04/2009 at 7:08pm
Back to Top
rjwoods77 View Drop Down
Milling Master
Milling Master


Joined: Jul/05/2009
Status: Offline
Points: 65
Post Options Post Options   Thanks (0) Thanks(0)   Quote rjwoods77 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/04/2009 at 8:17pm
Was the college built in a ditch? WTF is all that about?
Back to Top
dillon_b12 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/15/2008
Status: Offline
Points: 781
Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/04/2009 at 8:38pm
Louisville had the wettest July on record last month so the ground was saturated. The rain just came too fast and overwhelmed the drainage system. The vast majority of the water drained within a couple hours of the rain backing off.
Back to Top
Unproductive View Drop Down
Milling Master
Milling Master
Avatar

Joined: Jul/11/2009
Location: Rochester NY
Status: Offline
Points: 66
Post Options Post Options   Thanks (0) Thanks(0)   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: Aug/13/2009 at 4:07pm
Has anybody used or tested the maxxis 4 snow or ams zipper tires?


-Bob
Back to Top
charles ulaval View Drop Down
Milling Master
Milling Master
Avatar

Joined: Dec/31/2008
Location: Québec, QC
Status: Offline
Points: 67
Post Options Post Options   Thanks (0) Thanks(0)   Quote charles ulaval Quote  Post ReplyReply Direct Link To This Post Posted: Aug/19/2009 at 11:18am
I've heard that my team had puncture issues with those back in 2005.
They also enhance understeer (seen on sherbrooke baja at the Laval's Winter Race)


Edited by charles ulaval - Aug/19/2009 at 11:21am
Back to Top
dillon_b12 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/15/2008
Status: Offline
Points: 781
Post Options Post Options   Thanks (0) Thanks(0)   Quote dillon_b12 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/20/2009 at 12:33pm
Has anyone on here been involved with a car that used a prop or some form of propulsion other than the tire/fender combo?

Edited by dillon_b12 - Aug/20/2009 at 12:39pm
Back to Top
adrive7 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Oct/19/2008
Location: Lancaster, CA
Status: Offline
Points: 711
Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/20/2009 at 5:13pm
Originally posted by dillon_b12 dillon_b12 wrote:

Has anyone on here been involved with a car that used a prop or some form of propulsion other than the tire/fender combo?


We experimentally setup our 2005 car to run just a prop. Chain drive straight down to a prop off the engine. If you had the engine running full tilt as it entered the water you could get a couple feet before you stalled. If you tried spinning up while in the water, you pretty much stalled immediately. Also, cavitation was an issue.

It wasn't pursued after that, but maybe with some sort of cluch in between it could work. Or maybe a prop with less bite. But it adds a good bit of weight, and the water sections (Florida excluded) aren't very long.

http://www.facebook.com/album.php?aid=509670&id=12428067&l=81753148a4

http://www.facebook.com/album.php?aid=597046&id=12428067&l=dbfd298784


Edited by adrive7 - Aug/20/2009 at 5:16pm
-Joe
Chief Organizer, Baja California 2016, 2017, 2019
Ohio State Baja 2005-2009
Co-Host, Science... Sort Of
http://www.sciencesortof.com
Back to Top
Unproductive View Drop Down
Milling Master
Milling Master
Avatar

Joined: Jul/11/2009
Location: Rochester NY
Status: Offline
Points: 66
Post Options Post Options   Thanks (0) Thanks(0)   Quote Unproductive Quote  Post ReplyReply Direct Link To This Post Posted: Aug/20/2009 at 7:12pm
Originally posted by charles ulaval charles ulaval wrote:

I've heard that my team had puncture issues with those back in 2005.
They also enhance understeer (seen on sherbrooke baja at the Laval's Winter Race)


I could see the puncture issues, they are pretty thin. I don't think we would have any understeer issues with our swingarm rear suspension.

I think we're going to order a set to at least do some testing on.
-Bob
Back to Top
Kenneth View Drop Down
Milling Master
Milling Master


Joined: Jan/18/2009
Status: Offline
Points: 78
Post Options Post Options   Thanks (0) Thanks(0)   Quote Kenneth Quote  Post ReplyReply Direct Link To This Post Posted: Aug/20/2009 at 11:58pm
Of course the understeer issues would show up at the winter race where the rear tires have a ton of traction and the fronts have none. That is pretty irrelevant to how they would work on dirt. We ran the Zippers for the last two years at Winter Baja at Michigan Tech. We did it with Maxxis Razr-R's on the front in 2008 (Zippers all around in '09) and had tremendous accelerative traction and massive understeer, but even just crawling around the insides of corners, we were smoking the guys who performed nice-looking (and probably more fun) slides. We never tried them in the water, though we had considered it. Just never had a chance to test.
University of Michigan Baja Racing
Back to Top
bigusnickus View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Mar/18/2009
Location: Cincinnati, OH
Status: Offline
Points: 19
Post Options Post Options   Thanks (0) Thanks(0)   Quote bigusnickus Quote  Post ReplyReply Direct Link To This Post Posted: Aug/21/2009 at 10:34am
Dillon:
 
At RIT in 05' Ohio State tried an impeller from a late 80's kawasaki jet-ski. It was driven from a friction wheel attached to the end of the impeller shaft that was driven from the final drive sproket. We made our own water test tank and the impeller definetly worked, but it was insignificant. Those impellers were designed to spin at ~5-10k rpm and we were only generating 4 or 5 hundred.
 
It was a cool design, but that is all it was. Not practical in the least.
Nick Balzer Baja Buckeyes Alum 08'
BAE Systems Welding Engineer
Back to Top
charles ulaval View Drop Down
Milling Master
Milling Master
Avatar

Joined: Dec/31/2008
Location: Québec, QC
Status: Offline
Points: 67
Post Options Post Options   Thanks (0) Thanks(0)   Quote charles ulaval Quote  Post ReplyReply Direct Link To This Post Posted: Aug/21/2009 at 2:03pm
what is a reasonable weight for the floatation system with the fenders, for a good team? never had a baja for the water event!
Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/21/2009 at 2:40pm
Ours weighs in at around 40 lbs for everything water associated.
-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
thompm1 View Drop Down
Milling Master
Milling Master


Joined: Oct/23/2008
Location: VA
Status: Offline
Points: 72
Post Options Post Options   Thanks (0) Thanks(0)   Quote thompm1 Quote  Post ReplyReply Direct Link To This Post Posted: Aug/22/2009 at 3:40pm
40lbs is about right for most flotation systems.  The lowest weight water setup we've had (that i know of ) was in 2008 and it weighed in at about 25lbs dry, not sure about the weight after it got soaked though.
Michael

No Monkeys f**king footballs
Back to Top
asims View Drop Down
Welding Master
Welding Master
Avatar

Joined: Apr/07/2009
Location: Tucson
Status: Offline
Points: 184
Post Options Post Options   Thanks (0) Thanks(0)   Quote asims Quote  Post ReplyReply Direct Link To This Post Posted: Aug/24/2009 at 10:46pm
Originally posted by charles ulaval charles ulaval wrote:

what is a reasonable weight for the floatation system with the fenders, for a good team? never had a baja for the water event!


Along the same lines, what's a reasonable weight for a water car?  Obviously, lighter is better, but has anyone ever had a car that was too heavy to float with a practical flotation system?
Andrew Sims
University of Arizona
Back to Top
zehlerdj View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Nov/23/2008
Location: Clarkson
Status: Offline
Points: 34
Post Options Post Options   Thanks (0) Thanks(0)   Quote zehlerdj Quote  Post ReplyReply Direct Link To This Post Posted: Aug/25/2009 at 9:17am
IMO anywhere from 400-600 can be competitive at the water event. If it doesn't float you go down to the hardware or marina and get either some more foam or some buoys to strap on and try your luck with that. A lot of heavier cars in my mind are able to compete at the water event as compared to the midwest style races. Its still about being fast and strong either way
Dan Z.
Clarkson Baja
Team Leader
Back to Top
jeiB View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jul/17/2009
Location: Montreal
Status: Offline
Points: 604
Post Options Post Options   Thanks (0) Thanks(0)   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: Oct/24/2009 at 2:05pm
i have a question on the way teams attach their foam to their cars.

we are looking at the following choices:
- sandwich a hard core (sheet metal) in between foam layers with bolts attaching to brackets
-or using some kind of exoskeleton (pvc pipes?) to attach the foam in it, maybe even have a skin around the skeleton so that you can just fill that box up...

what do you think about the reliability? any other ideas?

thanks
Jeremie B.
McGill Baja Racing
2009-2011 Captain
minibaja.mcgill.ca
Back to Top
adrive7 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Oct/19/2008
Location: Lancaster, CA
Status: Offline
Points: 711
Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/24/2009 at 2:23pm
We would build a frame out of extruded aluminum inside the foam and attach to that. The whole thing would be wrapped in fiberglass or carbon/kevlar.
-Joe
Chief Organizer, Baja California 2016, 2017, 2019
Ohio State Baja 2005-2009
Co-Host, Science... Sort Of
http://www.sciencesortof.com
Back to Top
AndyRIT View Drop Down
Organizer
Organizer


Joined: Nov/11/2008
Location: Sheboygan, WI
Status: Offline
Points: 193
Post Options Post Options   Thanks (0) Thanks(0)   Quote AndyRIT Quote  Post ReplyReply Direct Link To This Post Posted: Oct/24/2009 at 8:38pm
RIT typically runs closed cell with carbon fiber, kevlar exo float using ratchet straps layed up into the composites to attach it to the car. Seems to work well for us, because if it comes loose then you can tighten up the straps easily.  I don't remember the tires that we used at TTU in 08'  
 
RIT Baja SAE Alumni 04'-09'
RIT Baja Team Manager 06'-08'
2010 RIT Track builder
2011 CAT/IL Comp Team Leader
2012 Wis vol
2013 RIT Track Builder
Diesel Calibration Engineer-Kohler Engines
Back to Top
CLReedy21 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Nov/30/2008
Location: Marysville, OH
Status: Offline
Points: 736
Post Options Post Options   Thanks (0) Thanks(0)   Quote CLReedy21 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/24/2009 at 9:59pm
We use a frame embedded into the foam.
-Chris Reedy
TTU Alumni
Fourwheeler Drawer



"Quick with the hammer, slow with the brain."
Back to Top
jeiB View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jul/17/2009
Location: Montreal
Status: Offline
Points: 604
Post Options Post Options   Thanks (0) Thanks(0)   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2009 at 1:20am
thanks for the help guys. 
Jeremie B.
McGill Baja Racing
2009-2011 Captain
minibaja.mcgill.ca
Back to Top
Dax View Drop Down
Bolt Sorter
Bolt Sorter


Joined: Oct/25/2009
Status: Offline
Points: 32
Post Options Post Options   Thanks (0) Thanks(0)   Quote Dax Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2009 at 7:26pm
I am just starting to figure out our flotation situation as this is our first year making a car float.
Is pour foam (polyurethane) better than the pink foam blocks?
McMaster Baja Racing
Back to Top
adrive7 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Oct/19/2008
Location: Lancaster, CA
Status: Offline
Points: 711
Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/25/2009 at 8:32pm
As far as floatation capability goes, they are both good.  Pour is a bit messier than the pink stuff, but probably cheaper. It can also conform to any shape you want. Pink is a little faster to work with. 
-Joe
Chief Organizer, Baja California 2016, 2017, 2019
Ohio State Baja 2005-2009
Co-Host, Science... Sort Of
http://www.sciencesortof.com
Back to Top
Waffles View Drop Down
Welding Master
Welding Master
Avatar

Joined: Jun/02/2009
Status: Offline
Points: 110
Post Options Post Options   Thanks (0) Thanks(0)   Quote Waffles Quote  Post ReplyReply Direct Link To This Post Posted: Oct/26/2009 at 11:04am
Expanded polyethelene foam with tubes which act like staples (and sliders) to attach the foam to the car.  The expanded polyethelene is very flexible without chunking or tearing, and doesn't need an external structure.  However it is heavier and does absorb water...  However you can pour gas/oil on it and it doesn't care...  Eh, just one way to do it..
Back to Top
Dax View Drop Down
Bolt Sorter
Bolt Sorter


Joined: Oct/25/2009
Status: Offline
Points: 32
Post Options Post Options   Thanks (0) Thanks(0)   Quote Dax Quote  Post ReplyReply Direct Link To This Post Posted: Oct/27/2009 at 10:44am
Is it practical to encase the pour foam in a shell to prevent it from absorbing water? or does that additional weight not offset the benefits?

McMaster Baja Racing
Back to Top
adrive7 View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Oct/19/2008
Location: Lancaster, CA
Status: Offline
Points: 711
Post Options Post Options   Thanks (0) Thanks(0)   Quote adrive7 Quote  Post ReplyReply Direct Link To This Post Posted: Oct/27/2009 at 10:50am
I would advise wrapping your floats in at least a couple layers of fiberglass simply for impact protection. They take a serious beating.

Just watch what resin you use. Make sure it won't dissolve your foam.


Edited by adrive7 - Oct/27/2009 at 10:51am
-Joe
Chief Organizer, Baja California 2016, 2017, 2019
Ohio State Baja 2005-2009
Co-Host, Science... Sort Of
http://www.sciencesortof.com
Back to Top
Dax View Drop Down
Bolt Sorter
Bolt Sorter


Joined: Oct/25/2009
Status: Offline
Points: 32
Post Options Post Options   Thanks (0) Thanks(0)   Quote Dax Quote  Post ReplyReply Direct Link To This Post Posted: Oct/27/2009 at 8:23pm
Thanks for the heads up on the foam eating resin, but I think I will probably be molding the foam chambers first out of fiber glass, then filling with foam, so there should be no issues in the foam being eaten.

I am in the process of designing a test rig for selecting the best tire tread from the ones we have around the shop for water, and then how deep it should be in the water for optimal performance. Has anyone done this sort of thing before, and how well did it work?
McMaster Baja Racing
Back to Top
Karan View Drop Down
Bolt Sorter
Bolt Sorter
Avatar

Joined: Oct/30/2009
Location: Manipal, India
Status: Offline
Points: 17
Post Options Post Options   Thanks (0) Thanks(0)   Quote Karan Quote  Post ReplyReply Direct Link To This Post Posted: Oct/30/2009 at 1:02am
Hey! I am from Manipal University, India, and we are taking part in a water event for the forst time. 
I'd like to know which rear suspension assembly is suitable for the water event? Double A-arms, Macpherson or Trailing arm.
Also I'd like to know about maneuverability in the water!! How to go about with this.

Thanks 
Karan Sharma
Team Captain
Team Manipal Racing
Back to Top
jeiB View Drop Down
Baja Godfather
Baja Godfather
Avatar

Joined: Jul/17/2009
Location: Montreal
Status: Offline
Points: 604
Post Options Post Options   Thanks (0) Thanks(0)   Quote jeiB Quote  Post ReplyReply Direct Link To This Post Posted: Nov/05/2009 at 8:58pm
A question regarding flotation.
32.5 Belly Pan - The cockpit must be fitted with a belly pan over the entire length of the cockpit…

Does that still apply if you have flotation foam over the entire length of the cockpit?
Jeremie B.
McGill Baja Racing
2009-2011 Captain
minibaja.mcgill.ca
Back to Top
Blue Devil's Erick View Drop Down
Bolt Sorter
Bolt Sorter


Joined: Apr/30/2009
Location: UW-Stout
Status: Offline
Points: 31
Post Options Post Options   Thanks (0) Thanks(0)   Quote Blue Devil's Erick Quote  Post ReplyReply Direct Link To This Post Posted: Nov/05/2009 at 9:27pm
What type of foam do most teams use in their floats?  I know we want closed-cell foam, but we are not sure what type.  I was thinking expanded polystyrene, but an really not sure.  I found a pourable foam capable of 60 pounds of buoyancy/ft^3.  Is there a more buoyant foam available at a reasonable cost?  We are on a very limited budget, so cost is a very important issue for us.

Also.......

How do other teams mount fenders to a-arm suspensions? 

This is our first year for floating, so I'll have lots of questions!

Erick


Edited by Blue Devil's Erick - Nov/05/2009 at 9:28pm
Back to Top
 Post Reply Post Reply Page  123>
  Share Topic   

Forum Jump Forum Permissions View Drop Down



This page was generated in 0.094 seconds.