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  1. #1
    Senior Member JJLudemann's Avatar
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    Default JJLudemann's Design Thread

    I guess I'd better start a design thread before I finish the design... I'm working on it full time, seven days a week. The frame is largely done but not tested yet, including mounts for A-arms, suspension rocker arms, anti-roll bars, steering rack, shocks, pedal cluster & master cylinders, front ARB adjuster, engine, differential, steering column, and all the associated brackets and jingly bits.

    Here's a recent rendering of the frame:

    http://s103.photobucket.com/albums/m...ssisTop006.jpg

    And here's the front end with some of the hardware attached:

    http://s103.photobucket.com/albums/m...artop005-1.jpg

    And here's a early version of the body:

    http://s103.photobucket.com/albums/m...t=Body0019.jpg

    -Jim

  2. #2
    Global Moderator carnut169's Avatar
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    Looks great Jim! Amazing how realistic the design software it- can't wait to see the real thing.
    Sean O'Connell
    1996 RF96 FC
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  3. #3
    Contributing Member RobLav's Avatar
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    Default

    Are you open for recommendations?

  4. #4
    Senior Member JJLudemann's Avatar
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    Default Criticism Welcome!

    Yes, I want to hear recommendations. If there's an area you'd like to see more detail, just ask. I'll be adding more in later posts.

    -Jim

  5. #5
    Not an aerodynamicist Wren's Avatar
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    How do you swap the motor?

  6. #6
    Senior Member JJLudemann's Avatar
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    Quote Originally Posted by Wren View Post
    How do you swap the motor?
    The motor will come out the bottom of the engine compartment, which will have its own separately removable stressed-skin belly pan. I figure I put up with that on 911s for almost thirty years .

    -Jim

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    Contributing Member RobLav's Avatar
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    Couple comments:

    - The rear rollhoop looks to be non-SCCA GCR compliant, unless you intend to do the alternate design method and have a registered engineer sign it off.

    - I too have done 911's (since 1975) and been changing engines since then. You should expect to it a lot more on an FB, and dropping the engine / raising the car will be a pain in the arse.

    - Try to increase the incident angle of the suspension pushrods to increase the motion ratio. Can you raise the bellcranks?

    - The rear structure is not triangulated in 3 dimensions.

    - The nose is pretty high, and you are on the edge (if not over) the gray area of the 1" deviation (we're all deviants!) rule. If you hit a curb or something hard, the bottom of the front rollhoop will bend or break. Your butt is not far behind that.

    - The angle of the universal in the steering rod is getting a bit steep. It'll probably work, but the tradeoff will be wear rate and potential lack of steering feel.

    Nice work though. Pretty amazing software.

  8. #8
    Senior Member JohnPaul's Avatar
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    Default Body work

    I think the Citation bodywork is one of the best: No overhead scoop and tiny sidepods. Try to get the bodywork as small as possible for less drag and weight. Just my $.02

  9. #9
    Contributing Member Rick Kean's Avatar
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    Default Concentric/sq.tube adjustable Stabar...!

    OK; just skip the "Concentric/" in my subject reference...

    Last edited by Rick Kean; 03.26.11 at 1:40 PM. Reason: eyesight strikeout

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    Front upper a-arm inboard mounts : expect a lot of flexing under braking - mounting to a tube in that manner (untriangulated) will eventually fatigue and break the tube.

  11. #11
    Senior Member Evl's Avatar
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    So I'm not a real engineer, so this is a question, not a suggestion: aren't all those bent tubes hard to manufacture and weaker than straight ones?

    Looks sweet though!

    What software are you using?
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    Default Tube flex under braking...

    Richard,

    You mean the upper rear a arm attachment to the chassis is the one that may flex, correct? The front one appears to have a chassis cross-member directly behind it, fixing it pretty damned substantially (laterally). Isn't it the upper rear a-arm attachment point that's suspect?

    Chris Crowe

    PS: A very cool redering of a very cool design effort, Jim. (Although I DO share in Rob's opinion concerning the 1" floor-deviation rule being violated between bulkheads A and B. The deviation pictured looks to be about three or four inches ot so).

  13. #13
    Senior Member JJLudemann's Avatar
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    Default Rob Lay's Concerns

    Quote Originally Posted by RobLav View Post
    Couple comments:

    - The rear rollhoop looks to be non-SCCA GCR compliant, unless you intend to do the alternate design method and have a registered engineer sign it off.
    This is because of a peculiarity of racing in Thailand, where I can't trust that the corner workers will help me out of the car if it's upside down, especially if it's on fire, so I want to have every inch of wiggle room possible to get out on my own. For this reason, I don't currently have the forward-facing roll hoop braces. Does anybody know if it's possible to get out of an upside-down car unaided? If not, maybe I should put the forward braces in.

    Quote Originally Posted by RobLav View Post
    - I too have done 911's (since 1975) and been changing engines since then. You should expect to it a lot more on an FB, and dropping the engine / raising the car will be a pain in the arse.
    On the cars where the back end comes off to remove the engine, how much re-adjusting does it take to reattach the rear end? I know you'd have to bleed the brakes, for instance, but is everything else repeatable? Do corner weights stay the same? It seems to me that being able to remove the engine without knocking any other systems out of adjustment may make up for the extra difficulty of taking it out the bottom.

    Quote Originally Posted by RobLav View Post
    - Try to increase the incident angle of the suspension pushrods to increase the motion ratio. Can you raise the bellcranks?
    I've tried to get them absolutely as high as possible. The shape of both the nose and the tail are dictated by the bellcrank positions, and there's not a millimeter to spare. The rear pushrod is 22.8 degrees from the ground plane and angled 10.6 degrees backward to clear the halfshaft. The rocker arm gives a 2.03 multiplication. So you've motivated me to do the actual motion study, and I come up with a motion ratio of 0.802. That's not good enough, is it . If I move the rear bellcranks up they start disturbing the clean air to the rear wing. Hmmmm... I also have to do the front motion study. Looks like I'll have to make some changes in this area. Is a minimum motion ratio of 1.0 absolutely required? How low do competitive designs go?

    Quote Originally Posted by RobLav View Post
    - The rear structure is not triangulated in 3 dimensions.
    Here's a better view of the rear with most hardware installed. Yes, it's clear I need a crossmember between the upper rails just behind the rocker arm mounts. Final details on bracing will have to wait for the finite element analysis, but it's awfully crowded in there already.

    http://s103.photobucket.com/albums/m...=cartop007.jpg

    Quote Originally Posted by RobLav View Post
    - The nose is pretty high, and you are on the edge (if not over) the gray area of the 1" deviation (we're all deviants!) rule. If you hit a curb or something hard, the bottom of the front rollhoop will bend or break. Your butt is not far behind that.
    The car will have a flat bottom shadow plate / splitter to keep it legal. As for crash protection, there are three layers of tubing before an obstacle gets to my butt. You can see most of it in this drawing, but there are also two diagonal crossmembers that form the base of the driver's seat:

    http://s103.photobucket.com/albums/m...nedrawing1.jpg


    Quote Originally Posted by RobLav View Post
    - The angle of the universal in the steering rod is getting a bit steep. It'll probably work, but the tradeoff will be wear rate and potential lack of steering feel.
    The steering column universal will be a double joint from Woodward, with each joint bending through a 20 degree angle. This is Woodward's exact specification for maximum recommended operating angle. I'm amazed you could see me pushing the envelope like that just by looking at a few photos .

    Nice work though. Pretty amazing software.[/quote]

    Thanks! And thanks for taking the time to look so carefully. Got to get my daughter to bed now. More later.

    -Jim

  14. #14
    Contributing Member RobLav's Avatar
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    Briefly,
    - Opinions vary wrt motion ratios. Mine is that .8 is do-able, but 1.0 or greater is much better.

    - Citations use steel male and female cone shaped threaded connectors to join the rear tubular structure to the rest of the chassis. The rear structure goes back to the exact same spot upon re-assembly - always. The male fitting is welded to the chassis tubes perpendicular to the chassis tube, and the female end goes inside the rear structure tube. An advantage to this is also that you can place the engine bay structure exactly where you want it, regardless of small welding tolerances. Weld the perpendicular bosses to the chassis first, then place the female connectors inside the engine bay structure loosely with rosette weld holes in the tubes. Put the rear where you want it, then weld the rosette holes inside the tubes. Minimizes stresses too. This method will be much better than trying to raise and lower the engine / chassis.

    - I don't think your dilemma in trying to exit an upside down car by yourself has occurred much here in the states. But I don't think one tube going rearwards from the rear rollhoop will be safe. Most upside down hits will put the one tube in compression. Not what we want.

    - If you re-design the rear to take into consideration my recommendations, make sure you do not stress the engine.

    - Lastly, opinions also vary wrt body and front wing position. I prefer a low front wing and very smooth, minimalist frontal area philosophy.

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    Quote Originally Posted by Christopher Crowe View Post
    Richard,

    You mean the upper rear a arm attachment to the chassis is the one that may flex, correct?
    Yes, the rear leg mount of the front upper a-arm.

  16. #16
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    Just a few things I was thinking about. A motion ratio of 0.8 might be ok, this is for the wheel/damper movement MR. I know some people say it should be the other way around but this is the definition I've always used. It all depends on how good your dampers are and how smooth the tracks are. A lower MR will give you more displacement in the dampers and higher shaft speeds. This will mean that the difference between the lowest and the highest shaft speed will increase and you will use more of the damper curve. So it could be easier to get the desired damping during different conditions. It also means that you can run lower spring rates, which will be lighter and put less bending forces on the damper shaft and reduce the internal friction in the damper. The obvious downside with a low MR is cavitation, so it's a question of how high shaft speeds can your dampers handle and what kind of speeds will they see on the tracks that you will race on. I don't know if someone here would be willing to share the highest vertical wheel speed that you see on a track and how often it happens. This would give you a good place to start. Then it's just a matter of calculating the shaft speeds for a few MR and go to a dyno and try those out.

    I would also go with a removable rear frame. I have swapped motors if quite a few FSAE cars and it's usually a hell. The ones that have been easiest are the ones where you split the frame/monocoque. If you don't want to bleed the brakes you could invest in a staubli quick disconnect. They are a bit expensive but a really nice bit of kit.

    How big is the distance between the rear upper outer a-arm point and the toe link? It looks a bit small to me. Try to increase it as much as possible, it will reduce the toe compliance and make the car more stable. Are you using the same uprights front and rear? Could you post an image of the upright with hub and brakes attached?

    I'm also concerned about the rear roll hoop support. Especially that the roll hoop is leaning forward and that there is no support going forward.

    The distance between the rear sprocket and the frame tube looks a bit small. I have been surprised a few times with how much the chain moves when driving.

    The upper mounting for the right diff holder will put a fair bit of bending on the tube. You might want to try to fit a tube going to the node where the upper a-arm front pick up is attached.

    I can't see how the front of the engine is attached, but there is a risk you will put a bit of bending on the tube holding the upper rear engine mounts.

    I'm also not too sure about the mounting of the rear dampers. Are there going to be some triangulation around there?

    I would really consider losing the clutch pedal. Or actually I would never design a race car with a bike engine with a clutch pedal. It can be nice when driving slowly in the pits or when spinning. But a well-placed and well done hand clutch works just as well. And from my point of view driving with tree pedals is just more uncomfortable and there is more risk of getting stuck when moving your feet around. I know a few people who have a really hard time driving with only two pedals in a formula car, but it shouldn’t be that hard to learn. Most people don't have a problem driving carts.

    I don't know if you have seen these master cylinders AP CP7854. It can be a bit more complicated to do the balance bar and package. But they are really nice and you can usually reduce the play and compliance compared with the normal balance bar.

    Other than that I would just try to move the suspension points as close as possible to the nodes on the frame.

    Looking like it could be a really nice car. I wish I had the time to do more designing and building the car I have been thinking about/designing for the past years. I was hoping to work some on it tonight, but I wrote this instead.

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    Default

    I'd also re-think the rear shock mounting - again, you have big loads fed into the mid section of long tubes.

    Also - the long clevis adjusters mounting the rear shocks will be very prone to bending. Better to mount the shocks directly to the plate rather than hang them out in the air like that. There also needs to be some triangulation of the mounting points of the cross bracket or the shock loads will move the bracket and the tubes around a lot.

  18. #18
    Contributing Member Rick Kean's Avatar
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    Default Connector visualization trouble; please help

    Quote Originally Posted by RobLav View Post
    - Citations use steel male and female cone shaped threaded connectors to join the rear tubular structure to the rest of the chassis. The rear structure goes back to the exact same spot upon re-assembly - always. The male fitting is welded to the chassis tubes perpendicular to the chassis tube, and the female end goes inside the rear structure tube. An advantage to this is also that you can place the engine bay structure exactly where you want it, regardless of small welding tolerances. Weld the perpendicular bosses to the chassis first, then place the female connectors inside the engine bay structure loosely with rosette weld holes in the tubes. Put the rear where you want it, then weld the rosette holes inside the tubes. Minimizes stresses too. This method will be much better than trying to raise and lower the engine / chassis.
    Rob,

    I have trouble visualizing this connector's layout, ; are the connector's male and female cone centerlines perpendicular to the tubing centerlines?

    Do you have any pictures of these Citation connectors?

    Thank you,

    Rick

  19. #19
    Grand Pooh Bah Purple Frog's Avatar
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    Default

    Richard has pointed out many good points. No reason to rehash those. Listen to Richard.
    You need to address the strain you are putting on many fixtures.

    When I look at your side view drawing, I'd raise the roll hoop. It's marginal at best. As noted by others it does not appear robust enough. A bit more height will give you some of the egress you seek. The Citation roll hoop is a good example of the ridgity you seek.

    If you watch videos of actual chain function, the amount of whipping going on can be quite surprising. Allow enough clearance.

    You don't need multiple centimeters of pedal adjustment. Having the driver's heels unencumbered by all those longitudinal rails will make foot movement smoother. A flat floor with basic heel rest will be easier to drive.

    Check out the steering on the new RFR1000, it may make a simplier steering solution than those two joints being maxed out. You do not want the steering shaft hindering the driver's foot movement.

    Another advantage to being able to "split" the chassis... you can, in time, build multiple configurations of rear chassis for both automotive and motorcycle engines.

    Where are you mounting the fire-bottle? Battery? The Tatuus mounted the fire bottle under the fuel cell. But it was a very special fuel cell, with an exagerated lower pickup. Putting the fire bottle under the fuel cell does raise the C/G a bit with a full fuel load.


  20. #20
    Contributing Member iamuwere's Avatar
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    Quote Originally Posted by Purple Frog View Post


    Check out the steering on the new RFR1000, it may make a simplier steering solution than those two joints being maxed out. You do not want the steering shaft hindering the driver's foot movement.


    Ok, PF, you have my attention. I can't find a picture anywhere. Any design that helps my size 14 feet find space makes me happy. Anyone with a shot?

    Jim

  21. #21
    Senior Member JJLudemann's Avatar
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    Default Re: Body Work

    Quote Originally Posted by JohnPaul View Post
    I think the Citation bodywork is one of the best: No overhead scoop and tiny sidepods. Try to get the bodywork as small as possible for less drag and weight. Just my $.02
    The body in the photos has to be considered a very early design. I did it first because I needed to have an envelope to fit the mechanicals inside of, although I did do a fair amount of CFD work on it. I got a huge increase in downforce (due to the cleaner air delivered to the rear wing) when I deleted the F1-style airbox so I'm pretty sure that's gone for good. I won't have 800 HP to push the airbox through the air like an F1 car, and the dynamic pressure it delivers to the engine appears good for only a tiny increase in power.

    The sidepods will go on a diet when I get back to aerodynamics. The trick is to make them as small as possible to hold the radiators, but still look cool. Got to look cool.

    -Jim

  22. #22
    Senior Member JJLudemann's Avatar
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    Default Re: Square Tube Adjustable Stabar

    Quote Originally Posted by Rick Kean View Post
    OK; just skip the "Concentric/" in my subject reference...
    Yup. It's a cylinder with flat faces machined on it, slots milled down the sides and center drilled for variable torsional stiffness along the length of the bar. Stiffness is adjusted by sliding the bar back and forth between the torsion arms.

    http://s103.photobucket.com/albums/m...llbarshaft.jpg

    -Jim

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    Senior Member JJLudemann's Avatar
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    Default Re: Front Upper A-arm Mounts

    Quote Originally Posted by R. Pare View Post
    Front upper a-arm inboard mounts : expect a lot of flexing under braking - mounting to a tube in that manner (untriangulated) will eventually fatigue and break the tube.
    You're absolutely right. Modified as shown:

    http://s103.photobucket.com/albums/m...=cartop008.jpg

    Clearly, more frame mods to come. I have an idea for the rear bellcranks, but need to analyze the front motion ratio first.

    Thanks,

    -Jim

  24. #24
    Senior Member JJLudemann's Avatar
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    Default

    Quote Originally Posted by Evl View Post
    So I'm not a real engineer, so this is a question, not a suggestion: aren't all those bent tubes hard to manufacture and weaker than straight ones?

    Looks sweet though!

    What software are you using?
    Manufacturability is not a problem here. Labor is essentially free but they need someone to design something cool for them to build. Strength will show up when I start the FEA of the frame.

    CAD software is Solidworks, rendering is by Maxwell Render.

    -Jim

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    Default To the entire gang ---

    -- is the illustrated front stepped floor area anywhere near legal in these depictions? I love what's shown from several points of view. But as I understand the GCR, it would be way out-of-the-ballpark in terms of the one inch floor deviation rule (at least).

    But then, I find this whole area of the GCR is very difficult to interpret. Even a simple stepped-floor concept would be in question if the rules are applied in the harshest, most conservative sense.

    So maybe this entire area is down to "rules creep" and what's what's customarily accepted is a bit different from what's literally specified.

    So. Would the chassis JJ has depicted have any chance of making it through the homologation process in actual practice? Could this chassis compete without fear of being DQ'd under protest?

    Hell. Lemme ask this: Can anyone better explain the entire "stepped floor" area of legality for me? Clearly, the chassis floor no longer has to be flat (within an inch); the "steps" in the RFR and Stohr (and others) are greater than this. But this seems to open a door: What if there were TWO steps in a chassis' floor? Then, what if those steps were "wavy" (gradual in nature) to attain some interesting aero effects? And etc.

    I know the answer to the extremes here is "no." But I don't know where the limits actually are. What's legal and what ain't legal floor-wise?

    Thanks,

    Chris Crowe

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    Chris:

    There is no 1" floorpan rule in FB (there is in FF and FC), so the floorpan looks to be OK if this were to be an FB car. The 1" rule for the undersides licked by the airstream in the controlled area is a different matter, and can be easily addressed by a horizontal splitter.

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    Default Thanks yet again, Richard ---

    I think what I find confusing is the "stressed panel" on the floor-plan. That is, if the chassis floor is fully V shaped, and that V-shape is capped (on both ends) at the front, steering wheel and roll bar bulkheads... well, you no longer really have a "space frame" car, but a monocoque. (Actually a semi-monocoque; a semi-monocoque... fully stressed-skin V-shaped [or even U-shaped] structure with an open top. Like all the first Formula 1 monocoques of the mid sixties).

    You've explained this to me before; one day I will hopefully understand. Another way of expressing my question is this: Could JJ's v-shaped floor be even a deeper V (or U) configuration than it is now? Say, a very deep v-shape, say six inches high and 10" wide? Is that still a "tube-frame" race car as F1000 is intended to be? Just how far can this gray area be pushed?

    Thanks again -- and please anyone, give Richard a hand -- I've been pestering him for more than a year in this area of grand confusion for me.

    Chris

    PS: Also could have sworn there was a stricture against more than a 1" deviation in the stressed-floor panel. This would negate the potential for much of the craziness (deep V or U shapes) above. But if that 1" deviation rule doesn't apply to the catagory, why not exploit this gray area all the way? Will again scrutinze the GCR.

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    Grand Pooh Bah Purple Frog's Avatar
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    Default RFR Steering Box

    The steering box I was telling you about...

    Last edited by Purple Frog; 05.13.11 at 12:52 PM.

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    I also would like to see pictures of the Citation cone connectors Rob mentions, anybody?......

    I think I found a picture that show what he was describing.
    Last edited by stephen wilson; 03.29.11 at 5:04 PM.

  30. #30
    Senior Member JJLudemann's Avatar
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    Default Re: R. Pare-- Shock & Bellcrank Mounting

    Quote Originally Posted by R. Pare View Post
    I'd also re-think the rear shock mounting - again, you have big loads fed into the mid section of long tubes.

    Also - the long clevis adjusters mounting the rear shocks will be very prone to bending. Better to mount the shocks directly to the plate rather than hang them out in the air like that. There also needs to be some triangulation of the mounting points of the cross bracket or the shock loads will move the bracket and the tubes around a lot.
    Correct again. I've moved the rear bellcranks forward and up, which allow me to use a longer arm to drive the damper & springs and gives a greater angle with the ground plane. My motion ratio (damper movement / wheel movement) is now 1.12, a significant improvement.

    Here's a shot of the new location:

    http://s103.photobucket.com/albums/m...ionrear002.jpg

    I did an FEA of the entire region of the bellcrank mounts and the result was just as you suggested:

    http://s103.photobucket.com/albums/m...ftrear2_02.jpg

    Now looking at how to brace it...

    Thanks,

    -Jim

  31. #31
    Dis Member Dano's Avatar
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    Stephen,

    I have highlighted the area that Rob was referring to. When the chassis and engine brace are separated you can see the chassis has a "male" tapered cone while the brace has a "female"cone. Take a look at Sean's blog (http://seanmaisey.blogspot.com/) and click on older posts until you get to a picture were he is mocking up the Honda engine....you will see what Rob was talking about.

    Dan
    Ingredients: Nothing but Barley, Hops, Water & Yeast.

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    Default Next question:

    How linear are your motion ratios?

  33. #33
    Contributing Member Rick Kean's Avatar
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    Default Citation style conical connectors

    Thanks Stephen and Dan for the references to Sean's blog.

    My take-away: To successfully incorporate Citation style conical connectors into a subframe design, all of the connectors must be fab'ed up with their centerlines parallel to each other.

    The trick is how to deal with subframe warping from the weldout, and Rob's suggested 'loosely fit female connectors + rosette welds' sounds like it works fine.

    Rick

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    Senior Member JJLudemann's Avatar
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    Quote Originally Posted by RobLav View Post
    - I don't think your dilemma in trying to exit an upside down car by yourself has occurred much here in the states. But I don't think one tube going rearwards from the rear rollhoop will be safe. Most upside down hits will put the one tube in compression. Not what we want.
    After looking at this again I started to feel claustrophobic when visualizing myself upside-down in a car with the minimum SCCA-required main roll hoop, so I've raised it by almost two inches, added the forward braces, and moved underlying structure to accommodate the changes.

    http://s103.photobucket.com/albums/m...=cartop009.jpg

    Quote Originally Posted by RobLav View Post
    - Lastly, opinions also vary wrt body and front wing position. I prefer a low front wing and very smooth, minimalist frontal area philosophy.
    The front wing will be low and flat unlike current F1 wings as our rules are more lenient. The only flexible frontal area is the side pods, which will most likely get smaller when I get back to aerodynamics.

    -Jim

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    Quote Originally Posted by Rick Kean View Post
    The trick is how to deal with subframe warping from the weldout, and Rob's suggested 'loosely fit female connectors + rosette welds' sounds like it works fine.

    Rick
    To help minimize warpage, the female connector is the last item to be welded into place, AFTER the rest of the subframe has cooled.

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    Senior Member JJLudemann's Avatar
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    Default Re: Motion Ratio Linearity

    R. Pare asked how linear are my motion ratios, but it looks like the post was deleted. Anyway, here's a plot of the rear suspension motion ratio. It looks like I have to reposition the zero point as I have only about 1" of useful linear wheel motion in bump.

    -Jim

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    Contributing Member RobLav's Avatar
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    JJ - What's the scale?

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    Senior Member JJLudemann's Avatar
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    Quote Originally Posted by RobLav View Post
    JJ - What's the scale?
    Those are meters of vertical wheel travel (about the nominal ride height) along the horizontal axis, and meters of spring extension/compression on the vertical axis. In wheel travel, bump is positive; in spring travel, compression is positive.

    So for example at 17mm of wheel bump, I get 27.1mm of spring compression. With a 1000 pound/inch spring, this gives me 1067 pounds of force (above nominal) generated by the spring. I think this gives me 884 pounds of vertical force (above nominal) at the tire (spring force x motion ratio x sin(pushrod angle)). Maybe tomorrow I'll figure out how to make SolidWorks tell me this automatically.

    -Jim

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    Dis Member Dano's Avatar
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    Jim,

    I was looking at the the side view of you chassis with the driver inside and was thinking what would his knees do if it was backed into a wall at a high rate of speed. Make sure that your dash is not mounted so solidly as to become a knee cap remover.

    It's kinda gross but...
    Ingredients: Nothing but Barley, Hops, Water & Yeast.

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    Senior Member JJLudemann's Avatar
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    Default Tire Force vs. Tire Movement

    I figured out how to make SolidWorks plot vertical tire force versus wheel displacement. It apparently blew SolidWorks 2009's little mind permanently and I had to upgrade to 2010.

    For those people I haven't yet replied to, I'll get to it...

    -Jim

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