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  1. mark512

    Bonding a Joint in Multiple Steps

    Hi all, This application would be using acrylic or epoxy as a structural adhesive. Here are some joint examples (lifted from http://www.adhesivestoolkit.com/): In the two examples on the very left, would it be acceptable to first bond the angle(s) to the vertical plate, and then later, when...
  2. mark512

    Gearbox sump & cover design resources

    Hi, I'm looking for gearbox sump & cover design resources, mostly with respect to fluid dynamics. To be more specific, here are two still images from a Shell video demonstrating their gear oil in a transparent gearbox. Static: Dynamic: There are several design features that I can see...
  3. mark512

    Lithium-Ion Battery Pack Architecture

    Thank you all for your responses! Sketchy design suspicions confirmed. Excellent. I was under the impression that that's the right way, but given Jehu's popular videos/kits, I was wondering if he might know something that I don't, but clearly the answer is NO.
  4. mark512

    Lithium-Ion Battery Pack Architecture

    I'm looking at the design shown in this video: https://youtu.be/bn0KtdrpoEM I've drawn a schematic of how I believe it works: Essentially it's a bunch of circuit boards, with each circuit board having a string of cells in series. The boards are stacked using standoffs, which also serve as...
  5. mark512

    True center-point steering geometry?

    I'm looking at the concept of "center-point steering" which seems to mean that there is zero mechanical trail and zero scrub radius (steering axis passes through the geometric center of the tire contact patch) or by some definitions, just zero scrub radius (steering axis passes through the...
  6. mark512

    Selecting Wheels and Tires

    I definitely second what CapriRacer is saying. If you're a huge OEM you can choose anything from a catalog you want or even get a custom size made for your product. But if you're a small manufacturer with low volumes, you'd best specify something popular if you're able to - it will be less...
  7. mark512

    Koni electronic controlled shock absorbers (dampers)

    To me, this looks like a regular brushed DC motor, not a stepper motor. 12V, 380mA sounds like a reasonable spec for the voltage and current. 14.4mm (0.567") seems like an odd diameter for a motor though. The "usual suspect" with small DC motors is Mabuchi Motor of Japan, however they seem to...
  8. mark512

    Koni electronic controlled shock absorbers (dampers)

    There are also standard stepper motor form factors, such as the NEMA frame sizes: http://www.piclist.com/techref/io/stepper/nemasizes.htm That would be the first thing I would determine - whether the size is standard or proprietary.
  9. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    I did end up getting a copy of that paper, it was a pretty good read, and really did only deal with front engine rear wheel drive (or at least only considered cars with double wishbones up front and a live rear.) I think it clicked now, is P2ss analogous/synonymous with Q-factor? With the...
  10. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    Got it, I was reading roll by lateral acceleration and was thinking it was some ratio of the two, but yes, peak vs. steady state of the transfer function of lateral acceleration to roll. Makes sense. ...though it's interesting that the Japanese cars have the lower damping and the Europeans are...
  11. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    That makes sense, as a few tire manufacturers offer calculations for determining the required tire load index, and all of them just boil down to the static weight on the tire. I'm going to take a look at that paper. And the whole applicability to front engine / rear wheel drive makes sense, as...
  12. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    I haven't come across "tire reserve" before but it does make a lot of sense. When you're talking about these percentages, what do you take as the rated and usage loads? My assumption would be that the rated load is the value indicated by the load index letter on the tire, and that the usage load...
  13. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    From here: http://www.optimumg.com/docs/Springs%26Dampers_Tech_Tip_2.pdf Though, it seems like my original question might be answered here: http://performancetrends.com/text-files/CTA%20Suspension%20Report.txt The "magic number" seems to be used in a few weight transfer worksheets: optimumG...
  14. mark512

    Total Lateral Load Transfer Distribution "Rule of Thumb"

    I've come across this rule of thumb in a few places that the total lateral load transfer distribution (TLLTD) with respect to the front axle should be around 5% greater than the static weight distribution with respect to the front axle. What's unclear to me is if this percentage is multiplied in...
  15. mark512

    ducted fan

    The first thing that came to mind here is the idea of disk loading: https://en.wikipedia.org/wiki/Disk_loading In particular, the relationship between disk loading and efficiency: Most light-to-medium lift helicopters operate at less than 10 lbs per square foot, yielding an efficiency of...
  16. mark512

    Roll center heights - I apologize in advance

    It's hard to trust random information on the internet, and it's difficult to even get a second source for any of them. For the S2000 this image seems to be floating around the S2KI forums: And this guy seems to do a lot of work with the S2000: https://robrobinette.com/S2000RollCenters.htm...
  17. mark512

    Roll center heights - I apologize in advance

    I'm pretty much sold on having no rear bar - you mention it a few times in your various posts, and in the Steve Lyman presentation I quoted before he also mentions he's not a fan of designs with rear bars. Looking at the math, it seems that if the CG is reasonably low and close to the middle of...
  18. mark512

    Roll center heights - I apologize in advance

    So I'm experimenting with how high I can raise the rear roll center, but keeping the front and rear spring rates the same, front anti-roll bar stiffness goes up to compensate for the rear roll center rising...but how stiff I can go? Steve Lyman did a Formula SAE presentation where he says: "My...
  19. mark512

    Roll center heights - I apologize in advance

    That's something I haven't thought of before, but it does makes sense. The F355 analysis http://rejsa.nu/forum/viewtopic.php?t=60154 claims that the very low roll center results in next to no tire scrub (track change) so as to not adulter the "contact patch feel" but it would follow that having...
  20. mark512

    Roll center heights - I apologize in advance

    I've been scouring textbooks and the internet regarding roll center heights, and in particular the front-rear difference (roll axis inclination) and why the rear roll center is often higher than the front. I've organized what I found into several theories: Theory 1 - Other suspension...

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