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About DaveThomasPilot

  • Rank
    Advanced Member
  • Birthday 12/14/1954

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  • Location
    Norh Carolina
  • Interests
    RC Helicopters, PCB design, Flyball, Private pilot, scuba diving, skiing

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  1. Teaching the wife

    Oh, and I'll use a rope between the wheel and the pole. So, if she steps off the wheel will be secured to the pole and continue with the cart, not at her.
  2. Teaching the wife

    So, my wife has finally agreed to try to ride my KS14C. She enjoys riding with me on her MiniPro, but its 10 mph speed limit sometimes seems a bit slow. She's really afraid of it, after seeing me ding my shins several times when I first started learning. I figure she'll punt if she even gets close to hurting herself. I read that the fastest way to success (or at least encouragement) is for the learner to hold on to a helper riding beside them. That way, they can use the support for balance until they get up a little speed, then experience what its like once they get rolling. That sounds reasonable to me, except that it seems like the helper won't be steady himself, after just mounting. So, when the learner will need the most help, the helper won't be able to provide much, without having to dismount himself. On foot, the helper would need to run to have a speed high enough for the learner to have an easy, steady, ride. So, I thought I'd try something a little different. I remember a water ski boat teaching device that used a rigid pole extending out from the side. Beginning skiers could hold onto the rigid pole instead of a ski rope and quickly learn how to get up on the ski(s)--the hardest part is just getting up. My "ski boat" is going to be our electric golf cart. I'm going to horizontally mount a pool pole on the vertical roof poles, behind the seat of our golf cart. I figure I'll mount it about waist high. She can ride behind the pole, several feet beside the golf cart, and use the pole for balance. She can also instruct me to go faster/slower. My goal would be to get her feeling comfortable going around 10 mph, then work on mounting using a wall. Pool pole might not be strong enough. If not, I could use a 2x4, with the end shaped to a cylinder for better hand gripping. Thoughts?
  3. P/N for MOSFETs used in Tesla?

    Thanks for the replies. I was worried they might be using the same FETs as were used in 67 volt control boards. But the IRFB4110 seems adequate from voltage breakdown standpoint:
  4. P/N for MOSFETs used in Tesla?

    Does anyone have a picture of the Tesla control board, or know what MOSFETs are used?
  5. Maybe this belongs in the "Mods, Repairs, & DIY" forum, but I thought I'd start here. I'm going to get either a 16s or a Tesla. I really like the idea of the higher voltage--assuming the control board designer knows what he's doing and used FETS with a sufficiently higher voltage specification. I worry, since there have been reports of FET failures. Could it be they are using the same FETS as in 67 volt boards? A higher voltage breakdown specification means either a higher Rdson ( on resistance), or a bigger (and more expensive) die. Bigger die have higher gate capacitance, and are harder to drive. Higher switching losses could result if the gate driver isn't scaled appropriately. Inexperienced power conversion designers sometimes chase low RDSon to minimize conduction losses in the FETS, and compromise reliability with a insufficient voltage margin. Has anyone seen a P/N on the FETs when their wheel was apart? It would be nice to check the specs on the FETS they are using. Otherwise, I'll go with the KingSong and avoid the higher voltage wheels until they have proven reliability. Failures should be in parts per million, not in the low percentage points. Otherwise, the problem is likely a design issue.
  6. My First Day with my new KS 16S - DISASTER!!!!

    I think you just had unreasonable expectations. My first day was about like yours (and the next several!). But, I knew it wasn't going to be easy. And, I just didn't (and don't) care about the scratches, etc, on the wheel. I did use a leash, but that was more about keeping the wheel from dinging me so much more than trying to protect the wheel. The shin guards you got look like what I finally bought. I should have used them right away. Typical--since I've worn them, I've never needed them. Keep at it!
  7. Learning to ride backwards !

    So, I did my first 20 minute session today. Not sure I made Day 1 on the "Marty Backe scale", but I was happy to find discover that what I needed to do to stay balanced wasn't counter-intuitive--it seemed the same as riding forwards. My biggest problem was keeping up the backwards speed. Every time I corrected for left or right turn tendencies, I ended up stopped, then having to dismount. It seemed like if I could just keep up my speed, I could stay balanced. I wish there was a way to bias the wheel to keep going backwards during this learning period. Maybe lean the wheel forward while calibrating? I've never tried calibrating the 14c, so I don't even know how to do it. I only saw one "dead chicken"" incident in Marty's videos (the first one, I think). I had several today. I'd suggest wearing boots and shin guards in addition to the helmet. Maybe Marty didn't have the painful run-ins with the pedals when first learning to ride forwards that I did. The boots and shin guards weren't needed today, but easily could have been, depending on what the wheel decided to do when I jumped off. Thanks Smoother, -- I'm also wearing the wrist guards. I have to step back and say just how great this is. It's like going back to being a kid and re-living the thrill of first learning to riding a bike . Best available substitute for a fountain of youth! (well, that's probably an overstatement, but you get the idea). It didn't seem like fun for the first few frustrating sessions trying to ride the EUC forwards, but the harder it is, the more satisfying riding backwards will be once it clicks!
  8. Learning to ride backwards !

    Marty's videos and the posts here have really motivated me to give backwards a try! I'm an old guy, so if I can do it, probably anyone can. Gotta ask, who's the oldest one around that can ride backwards? Or, who's the fattest? Maybe I can be the first at something!
  9. Learning to ride backwards !

    Thanks! for others, here's a more direct link to Marty's riding backwards videos: http://forum.electricunicycle.org/topic/1019-the-video-thread/?page=100&tab=comments#comment-83223
  10. Learning to ride backwards !

    I was searching for tips on how to learn to ride backwards and came across this post. Do any of the EUC veterans have any more tips?
  11. KS14C versus KS14S/KS16S

    k, thanks. I figure shipping might approach $100. So, I'd keep it for the batteries if I can't drop it off at an airport.
  12. KS14C versus KS14S/KS16S

    Just listed the 14C: http://forum.electricunicycle.org/topic/8847-ks14c-for-sale-near-raleigh-nc-500/ If it doesn't sell for $500, I'm thinking I could probably use the batteries in my new wheel, or at least build a spare battery from the cells. I figure the battery itself gotta cost nearly $500.
  13. What redundancy options do manufacturers have?

    EUC power redundancy doesn't need super-caps. Just use parallel cells for the redundancy. The connectors may be less reliable than the battery, but you have that issue with a super cap too. Yes, our situation is much worse than a helicopter. Learning to do an auto-rotation is basic training for a helicopter pilot. A 6 phase motor with 2x3 phases with each set of three phases being driven separately would make me feel a lot better. But, it might be pretty tough to get the control loop fast enough to respond to a failure of one side to prevent a face-plant while not being too responsive to maintain stability when both sides are active. It seems that development of the control loop dynamics is an empirical process, based on the issues that surfaced when the first 84v wheels came out. Real redundancy would probably approach 2x, but I'd pay for it if it could be demonstrated that a large fraction of single point failures wouldn't cause a face plant.
  14. KS14C versus KS14S/KS16S

    Yeah, that's the question all right. I should make a mock up of the 16s and see how it fits in the plane and pick up. Also, I lost enough weight so I netted a lower payload when carrying the 14C along. Now, it looks like I have to loose a few more pounds!
  15. KS14C versus KS14S/KS16S

    Yes, it's pretty nice having and flying a private aircraft in the US. Buying used cars instead of new for a couple of decades pays for plane. The gas does get expensive though... EUC's are perfect carry along transportation. We used to have folding bicycles, but the wheels are much more compact and those bikes were horrible to ride with their tiny wheels. Every time we land at an FBO and pull out the PTDs to get off the tarmac I get lots of comments from other pilots on what a great idea it is.