andy666 Posted August 21, 2014 Report Posted August 21, 2014 So what is better for high speed? Heavy or Light? I know that conventional thinking is a big heavy buggy so you can hold the power and get more grip. But I have been thinking about it lately and wondering if a large, but light weight buggy might be better for outright speed. Buggy would ideally be around the 25kg mark. But still be large and stable. Using barrow wheels, single layer canvas seat, 1.5m carbon axle and thin wall tubing. My theory is that with a lighter buggy a smaller kite could be used, which should be faster through the air. Also with a wide enough beach (or salt lake) there wouldn't be any need to fight against getting pulled sideways, instead just steer a little further downwind and go with the power. thoughts? Quote
jdhot Posted August 21, 2014 Report Posted August 21, 2014 Hi Andy, Just some tips that I have found in the pursuit of speed 1/ I had a Trikz buggy - large, reasonably light for a large buggy, it was quick 2/ I have a set of larger narrow tyres, but the problem was if the wind direction wasn't ideal or no room for correction they would be pulled easily slide ways. Even with camber added. Narrow tyres I feel are best suited for the perfect arenas like salt flats etc where you can flow with the wind direction as they do in the States (the big speed week event) 3/ Best choice I found was large duro tyres pumped up to about 30ish PSI which really rounded out the face of the tyre running on a narrow centre, but the extra grip available if pulled sideways. Take into consideration I only have beaches to run on with limited width, and never had the perfect conditons Lucky over the past few years to have any conditons in my area, wind-tides-rain Good Luck with your speed attempts JD Quote
BobM Posted August 21, 2014 Report Posted August 21, 2014 My theory is that with a lighter buggy a smaller kite could be used, which should be faster through the air. Also with a wide enough beach (or salt lake) there wouldn't be any need to fight against getting pulled sideways, instead just steer a little further downwind and go with the power thoughts? Andy, Try the dried lake bed at Kingston! Oh Wait you've moved further away :-( JD, When are you going to bring the skinny wheels to Kingston lake bed? Quote
Tiger37 Posted August 21, 2014 Report Posted August 21, 2014 I am no expert Andy but in general terms the heavier something is the more difficult it will be to move. I suspect there are too many variables involved such as the weight of the person, the rolling resistance from the tyres and surface, the size and style of kite and of course our good friend, the wind. So may be you should experiment using the same kite in the same conditions and make the buggy weight the only variable by adding weights each run. Just a thought. Quote
sinbad Posted August 21, 2014 Report Posted August 21, 2014 Norm should give us some comments on this re aerodynamics. My under standing is heavy buggy will just take a bit more effort to get it going, then rolling resistance will come into it, bearings and then increased drag from tyres, then as the speed builds aerodynamics will come into play. So lighter is not exactly the governing factor of going faster. Quote
BobM Posted August 22, 2014 Report Posted August 22, 2014 Norm should give us some comments on this re aerodynamics. My under standing is heavy buggy will just take a bit more effort to get it going, then rolling resistance will come into it, bearings and then increased drag from tyres, then as the speed builds aerodynamics will come into play. So lighter is not exactly the governing factor of going faster. A heavier buggy will have greater friction with the surface it is rolling on, and thus a larger sideways force will be needed to change rolling friction into sliding friction (aka breaking out), but the acceleration will be less for a given force F=Ma (force equal mass times acceleration). A heavier buggy will allow you to go faster, it will just take a bit more time to reach the top speed. Quote
sinbad Posted August 22, 2014 Report Posted August 22, 2014 A heavier buggy will have greater friction with the surface it is rolling on, and thus a larger sideways force will be needed to change rolling friction into sliding friction (aka breaking out), but the acceleration will be less for a given force F=Ma (force equal mass times acceleration). A heavier buggy will allow you to go faster, it will just take a bit more time to reach the top speed. Thats what i said Quote
SoutherlyBuster Posted August 22, 2014 Report Posted August 22, 2014 I think there is a battle between the "ideal" and the "practical" here. A heavier buggy for the same tyres/pressure will give more rolling resistance, but this can be tuned out by adjusting the pressure. As I've seen with various landboard devices, the larger the wheel diameter the lower the rolling resistance, the faster you go, ie 8" types on a 4W landboard versus the BMX size tyres of a Dirt Surfer. Pump the tyres too high and you start to slide side ways. Let's assume we've sorted out the wheel friction, side pull, and over turning issues. As others have said, I agree, the heavy buggy will tend to take a bit longer to reach top speed, ie F=ma, the bigger the mass the lower the acceleration. Then your limiting factor, kite aside, would be wind drag on the pilot and buggy, the aerodynamics Terry was talking about. Eventually you will reach a terminal velocity. Hmm, how do you like Lycra Andy? So now we are the stage of needing a very long run way to build up the speed and in the perfect direction. On the landboard, I found this was the limiting factor at Kingston last year, just ran out of usable land (ie either coming up to the scrub or sticky mud). Now comes the "ideal" versus "practical". The "ideal" may say, a heavy buggy with large diameter tyres, and a mega big kite for plenty of power (ie before the buggy tips over). The "practical" says, what is safe given the unpredictable wind, ie gusts. Now we enter the risk aspect, what risk are you willing to take? Provided the kite is stable enough a smaller kite would be safer, ie look at what Neil at Kingston does; then at the other end of the spectrum you have a large depower piloted by none other than Criss (mad ) Italy at Kingston, much bigger risk. Ofcourse we can't forget Nigel, as he still does have the AU speed record. Small depower, standard Libra (correct me if I'm wrong, or was it a Peter Lynne?), and crazzy winds -- Sandy Point. So, I think it's important who the pilot is, what risk they want to take and where they are going to try and get their personal best. Regards, Norman. Quote
andy666 Posted August 22, 2014 Author Report Posted August 22, 2014 Well everyone seems to agree that a heavy buggy gives more traction, but takes longer to get up to speed and requires a bigger kite. I agree too. BUT, what if you didn't need to worry about sideways traction because you were on a salt lake and could simply steer further down wind instead of sliding sideways? Would a lighter buggy be better in this situation? Could a smaller kite be used to achieve the same top speed? Quote
sinbad Posted August 22, 2014 Report Posted August 22, 2014 Im never doing kingston again if Norm and Chris turn up in Lycra what a sight. Quote
Clive Posted August 22, 2014 Report Posted August 22, 2014 Having both large and small buggies, it's chalk and cheese..... Big is best. Period ! What can be done in a small buggy can be done far more comfortably and safer in a big one. There's a reason race buggies are big, check out the races, no small buggies in the lead. Quote
andy666 Posted August 22, 2014 Author Report Posted August 22, 2014 Not small, just light weight. Quote
plummet Posted August 22, 2014 Report Posted August 22, 2014 hmmmm. The bigger/heavier you go the less manuvourable you become. I'm currently condisdering big wide race size bug v my compact ish bigfoot bug. I really like the zippiness of the smaller buggy. but I know I will be able to go faster in the monster buggy. What will make me grin the most? small light agile fast accelerating? wide, low, fast? Quote
SoutherlyBuster Posted August 22, 2014 Report Posted August 22, 2014 Ok Terry no lyrcra, how'bout just speedos then Andy, going more down wind has it's limits, eventually you will be going with the wind and well, the lines go slack and you don't go any fasster. Plummet, you have the right idea, the fun factor. What puts the biggest grin on your face, that's all that matters. Personally I'd be scared sh^****^%%%^%^less riding a 200 kg buggy that is slow to steer and get out of trouble. I reckon Clive's right, the size he's using seems perfect. Now back to the fun factor, big buggy with low rolling friction, small crazy kite and big winds, hey sounds like fun, so who cares if you go faster or not? Sounds like fun. Hmm, am I back to what Andy proposed in the first place ..... . Quote
Clive Posted August 23, 2014 Report Posted August 23, 2014 Not small, just light weight. No light weight ones in the lead either Andy Same problem, lack of weight =lack of traction, remember the saying.... Fat guys go faster.... bigger wheel base = stability The racers would have nailed all this long ago if weight was the issue, titanium frames, helium tyres, light weight materials have been around for ages. Plummet, you have the right idea, the fun factor. What puts the biggest grin on your face, that's all that matters. Yep wholly agree, doesn't matter if you're running a homemade buggy with a NASA kite, or a full race buggy with a vapor, fun is foremost. Quote
Slartibartfast Posted September 29, 2014 Report Posted September 29, 2014 BUT, what if you didn't need to worry about sideways traction because you were on a salt lake and could simply steer further down wind instead of sliding sideways? You always need sideways traction. It's the side traction that gives you the purchase to build speed. Imagine a water skier holding onto a rope attached to a boat traveling at a constant speed. The skier has the option of pointing there skis directly inline with the boat and traveling at boat speed or they can carve across the line with there skis perpendicular and travel across behind the boat. If they're able to keep a hold of the rope and dig the edge of the board/skis in they will be able to achieve speeds far in excess of the speed of the boat and effectively slingshot them selves off to the side (think 'inclined plane'). The other thing to remember is the difference between true wind and apparent (or relative) wind*. As you build speed the difference between the true and relative wind widens and with practice you'll be able to go significantly faster than the wind, with the current land sailing speed record achieving an astonishing 5x wind-speed! This means no matter what direction you are going the relative wind is always from in front of you. Not straight in front but if you were able to get to 3x wind speed, even on a broad reach (the widest possible angle) this wind will be coming to you from only 20-deg of straight ahead. This necessarily means the kite will be off to one side at the edge of its window and will be pulling you sideways. In any event, if you have less traction it means you will not be able to hold as much tension (i.e. force from the kite) and will need to 'bear off' down wind. As you bear off the power from the kite drops off dramatically so you want as much traction as possible to allow you to "bear up" and keep maximum tension in the lines. It is after all this line tension that ultimately provides the force that propels the buggy. The good thing about being on a clay pan is you always have the option to dump power by bearing off and regain it by "bearing up" again. This effectively means you get to tune your perfect "point of sail" with out restriction. There is however no doubt that the more traction you have the more 'tension' you'll be able to hold and consequently the faster you will be able to go. * I prefer the term 'relative wind' to the more correct 'apparent wind' as the word "apparent" makes it sound like an apparition. Quote
gannet Posted September 30, 2014 Report Posted September 30, 2014 Light buggy , light wheels big diameter 27" max for class 8 . length; I run 2.6m total o.s. wheels and a 1650mm rear axle. Kite Ozone Quantum 4m. wind ; about 35 knots on a convex beach. start with the wind at about 30 deg, max speed at 15 deg = 108 km/hr Quote
andy666 Posted September 30, 2014 Author Report Posted September 30, 2014 108kmh that's incredible, congratulations! I watched the video and it looked like there were a few nervous moments when the gusts hit. But the question is. Do you think you would of gone significantly faster in a heavy buggy? Quote
Clive Posted September 30, 2014 Report Posted September 30, 2014 That's mighty quick. Plenty of sideways drifting through the run, glad you didn't hit a soft patch, remarkable effort. Quote
Clive Posted September 30, 2014 Report Posted September 30, 2014 But the question is. Do you think you would of gone significantly faster in a heavy buggy? No I think the question is, do you have the balls to go any faster...... Quote
Slartibartfast Posted September 30, 2014 Report Posted September 30, 2014 Bloody Hell! That was terrifying!!! Do you have the GPS trace available? It would be really cool to overlay the video footage with graphics from the GPS data. What do you say jabroni, are you up to dusting off your php skills again? Quote
nigel Posted September 30, 2014 Report Posted September 30, 2014 Sweet job there Gannet!!! The kite looked like it was a handful at times. Quote
gannet Posted September 30, 2014 Report Posted September 30, 2014 That's mighty quick. Plenty of sideways drifting through the run, glad you didn't hit a soft patch, remarkable effort. Yip, same here , but I used the soft sand to slow down at the end Quote
gannet Posted September 30, 2014 Report Posted September 30, 2014 No I think the question is, do you have the balls to go any faster...... Quote
gannet Posted September 30, 2014 Report Posted September 30, 2014 Bloody Hell! That was terrifying!!! Do you have the GPS trace available? It would be really cool to overlay the video footage with graphics from the GPS data. What do you say jabroni, are you up to dusting off your php skills again? Bloody Hell! That was terrifying!!! = maximum adrenalin I would have to check if its still in one of the 3 GPS's as I have reset them Quote
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