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Old 08-07-2013, 10:55 PM   #151
Midnullarbor
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John82q, your post #146 has just put a torpedo through my thoughts.

I was thinking the dust had settled on the question of whether lifting the car "as a last ditch effort" was a method of saving the bacon and avoiding running out onto the wrong side of the road. And the consensus being that it wasn't effective (because "lifting" must result in a widening of the cornering line).

Best I go away and chew it over for a while, until I can get my thoughts straight so I can express things more clearly.




For the moment, let me say : I think the "lifting" idea is a fallacy, because it doesn't account for the fact that (to stay shiny side up) the support point for the outfit's C.o.Gravity MUST stay in the "triangle of stability" ~ which includes the triangle's edges [the three so-called "tipover lines"].
Look at HogWild's pic @ #113 of dirt racing. Spectacular ~ but the guys are still keeping it (the C.o.G) within that triangle of stability.

Sorry to harp on about the old "triangle of stability" which Hal Kendall and others have described ~ but that triangle is absolutely vital to understanding the dynamics of outfits.

Even if you swing the front wheel and/or slide the outfit, to point say 5 degrees tighter into the turn, the outfit can't in reality follow that tighter line . . . because you haven't (yet) dealt with all the outfit's momentum [outwards] in the old wider cornering line (where the chair had started to lift . . . because you were already too fast for the old wider line).




Picture yourself running on your feet . . . but you urgently need to change the line you are taking.
Nice to be able to *literally* turn on a dime, and head off in the new direction . . . but unfortunately, it can't actually be done like that. In reality, you have to LEAN further into the turn and (rather gradually) swing towards the new heading. During the turn, your support point [your feet] has to be further outwards than your body.

Not much different with a solo bike ~ you can simply lean further into the turn.

But on an outfit, the "equivalent action" takes your support point "outwards" too.
When you are already cornering at the limit, then "further outwards" means PAST the tipover line . . . which means . . . well, you know what it means.

To save yourself from tipping over, you MUST take a wider line (even if only temporarily) ~ and that's when you might find that you've taken yourself out of the frying pan and into the fire-red SUV coming the other way.
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Old 08-08-2013, 06:35 AM   #152
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Midnullabour,

To be clear,I m not protomoting lifting or flying the chair as a way to save your bacon, choosing proper entry speed, and line for the corner and your rig does that. Thing is though, the chair rising is the inevitable result of not getting those things right. (as opposed to the flying the chair on the balance party trick, that might get you laid,,,but most likely not)

I,m just a little more optomistic than mr hogwild.
If it tightened the radius and where you were going by 2 ft, then you loose 1 ft 6 to prevent tipping over, and the remaining 6 inchs might be difference between impact or a very near miss. never,never, ever, give up, right?

Before thinking about it too much go have a good fang, circle work or twistys...
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Old 08-08-2013, 07:47 AM   #153
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Quote:
Originally Posted by Midnullarbor View Post
Look at HogWild's pic @ #113 of dirt racing. Spectacular ~ but the guys are still keeping it (the C.o.G) within that triangle of stability.
This is incorrect, as well as a number of your other assumptions above. If the chair is held at the same height for any period of time, by definition you are balancing on the front and rear wheels. Therefore, the "CoG" as you call it is being held right on the line between the front and rear wheels, which is NOT "inside" the triangle, but rather right on the line at the edge of the triangle. I wish I had the time to discuss this in more detail.

As others have said, it takes a lot of practice to get a good feel for how the rig handles with the chair up. Raising the chair can allow you to turn SLIGHTLY tighter, for a short period of time. ONLY lifting the chair (not shifting your body weight or changing your speed) does not allow you to HOLD a tighter turn for any period of time. It just allows you to shave a few inches or feet off the end of the turn, in your favor. Of far more value would be slowing down and/or shifting your weight to the inside. Unfortunately in an emergency situation you generally don't have much time to do either of those.
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Old 08-08-2013, 07:57 AM   #154
claude
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Quote:
Originally Posted by HogWild View Post
This is incorrect, as well as a number of your other assumptions above. If the chair is held at the same height for any period of time, by definition you are balancing on the front and rear wheels. Therefore, the "CoG" as you call it is being held right on the line between the front and rear wheels, which is NOT "inside" the triangle, but rather right on the line at the edge of the triangle. I wish I had the time to discuss this in more detail.

As others have said, it takes a lot of practice to get a good feel for how the rig handles with the chair up. Raising the chair can allow you to turn SLIGHTLY tighter, for a short period of time. ONLY lifting the chair (not shifting your body weight or changing your speed) does not allow you to HOLD a tighter turn for any period of time. It just allows you to shave a few inches or feet off the end of the turn, in your favor. Of far more value would be slowing down and/or shifting your weight to the inside. Unfortunately in an emergency situation you generally don't have much time to do either of those.
We are at a point wher ewe are splitting hairs somewhat I think. Anyone want to think back to when they learned to ride a bicycle? How did u learn? It is hard to explain and cannot be done without practice. I do not disagree at all with Scott on what he has written above and earlier and hope he can make some more time to explain it in more detail. However no amount of words will even bring one to the point that the actual 'doing ' will get them to. We can get into center of gravity ...center of mass... moment arms and all kinda of things but none of these will ever make a difference that actual seat time can make. Most Engineering and dynamic suspension related terms do have much merit but the feel from the wheel, so to speak is what counts.
As far a tip over lines go they may be fixed in relation to the wheel placements on an outfit but how they actually react to a given situation depends on other factors in addition to these things. Come on Scott bring this to a new level hoppefully others will chime in and we can go from there. lol.
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Old 08-08-2013, 10:10 AM   #155
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Originally Posted by claude View Post
Come on Scott bring this to a new level hoppefully others will chime in and we can go from there. lol.
I think you said it very well. I can talk at length about the moments, gravity, centrifugal force, counter steering, and all the physics. I could even dust off my old physics and dynamics books and throw a calculation or two out here. But what you said above is of much more value. More practice and riding time will be much more valuable in a case of "going in too hot" than any amount of theory. I can guarantee you, ten time World Sidecar-Cross Champion Daniel Willemsen can do magic with a sidecar, riding on any wheel he wants, in almost any circumstance imaginable, at crazy speeds, yet he probably could not talk in proper physics terms for 10 seconds.

I'd much rather passenger with an experienced rider who dropped out of high school than passenger with Albert Einstein driving! If I were driving though, I'd probably pick Einstein as passenger, just to see what he thought of a "flying the chair" experience!
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Old 08-08-2013, 06:00 PM   #156
Midnullarbor
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HogWild, I gotta disagree with you . . . at least partly.

You are splitting hairs if you wish to say that the tipover lines are not part of that dreaded term "triangle of stability".
They are part of the triangle ~ and some refer to them as the balance lines.

If you are going along steadily on the balance/tipover line (or well within) then you are okay . . . but if the chair starts to lift, then it's a sign that you've gone outside "the triangle" and that you'd better do something immediately to take charge of the situation.

Most of us are aware of that intuitively . . . and we don't need to be Einstein.




BTW, the tipover line is not a string-thin sharp edge, but more like a band 1 to 2 inches wide depending on the wheels' contact patch sizes.
So it's a bit fuzzy, which gives you a narrow bit of operating space to play around with (when you've gained enough skill).
But when you are well over that fuzzy line, then all those momentums & centrifugal forces etcetera will start to bite you.
Good to think about them, before you practise on the road.



While I can't say I positively enjoy being corrected over my errors . . . nevertheless I welcome you (or anyone) hitting me over the head and pointing out where I am wrong.
I'd rather be embarrassed and set right, than carry on naively being wrong.
So please jump in and specify any errors in my past posts (though keeping in mind that some apparent errors may turn out to be a misinterpretation of what's written ~ like with the triangle business).
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Old 08-08-2013, 08:31 PM   #157
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Quote:
Originally Posted by Midnullarbor View Post
You are splitting hairs if you wish to say that the tipover lines are not part of that dreaded term "triangle of stability".
Yes, splitting hairs. I read your word "within" and interpreted that as meaning "inside" the triangle, not ON the outer edge. To further split hairs, typically while flying the chair for a period of time, you're actually crossing back and forth over the line, as the hack goes up and down a bit. If the hack is moving up, CoG is outside the triangle, and when it's moving down, CoG is inside the triangle.

Quote:
Originally Posted by Midnullarbor View Post
Even if you swing the front wheel and/or slide the outfit, to point say 5 degrees tighter into the turn, the outfit can't in reality follow that tighter line . . .

To save yourself from tipping over, you MUST take a wider line (even if only temporarily) ...
.
Both of these are incorrect. There are several ways to turn sharper without widening your turn:
1) Slow down. The slower you get, the sharper you can turn.
2) Lower your body, which lowers the CoG, which allows a sharper turn.

And there are several ways to turn sharper by only momentarily widening your turn:
3) Lean your body more towards the inside of the turn, which moves the CoG, which allows a sharper turn.
4) Break the rear wheel loose and start sliding the rear end out, which scrubs off speed, which changes the CoG, which allows a sharper turn. Adding gas while sliding the rear out can actually help turn sharper, because the direction the rear wheel is pointing (the forward acceleration force from the rear wheel) will be more towards the inside of the turn. This is a staple in dirt sidecar racing, but almost impossible on pavement. Don't do it on pavement!
5) Turn hard the OPPOSITE direction and jam your brakes on, spin out 350 degrees, then accelerate off in the new direction (don't laugh, it's been done). On pavement this would probably not work out well (you'll flip instead of spinning out), but on just the right slick dirt road it can work.


Per #2, notice the driver is not only leaning towards the inside of the turn, he's also lowered his body significantly. Lower is faster.


Per #4, here the World Champ is getting around this turn the fastest way possible, by sliding the rear wheel out, and applying gas at the same time.
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Old 08-09-2013, 06:22 AM   #158
Midnullarbor
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Thanks, HogWild, you raised some good points, as usual.

As to the "splitting hairs" matter, I reckon we are basically on the same page about what's going on.
I do feel uneasy about your use of "CoG" ~ which probably you are using as shorthand for "the support line going up from the ground and through the CoG" or some such horribly long phrase.
Shorthand is good, provided that everyone understands it . . . but on other sub-forums on ADVrider, you will have found a few guys who just don't "get" CoG.
But I am guilty of shorthand too, with terms like "support line", and so on.

Daniel Willemsen certainly does some marvellous things out on the dirt track ~ and perhaps as Number One it's difficult for him NOT to. You are being "poetic" in describing it as Magic ~ 'cos even he has obey the laws of nature in this physical world. Momentum and CoG and all at scientific stuff can't be evaded . . . though when he's in mid-air, you might almost believe he has.





Your next quotes of mine were taken slightly out of context, but not too badly.
But it's been a long thread [partly my fault], and I doubt you've got time to go back and carefully re-read & weigh & ponder on the various points I [and others] have mentioned . . . but I fancy that if you did, you would find we are in less and less disagreement than your first impressions.

Back at the start, Haggis the OP was dealing with his 1500cc outfit ~ a shade heavier than Willemsen's rig, and possibly not used much on dirt.
That said, there are the 5 points you listed[lists are fun . . . sometimes] :-


1. Slow down. Couldn't agree more ~ but it is easier said than done.
Once the chair is up (and you've caught it and kept it lofted) significant braking becomes a real handful of difficulties . . . and even more so on dirt.
And when you think about it, "catching the chair" must involve straightening your line a bit (to get the CoG in proper position relative to the tipover/balance line).
Unless you are on a very tight/slow corner and a very wide lane . . . then you will find yourself crossing that central painted line.

The alternative : putting the chair down so your braking can be stronger (on the two outer wheels) will also mean some line-straightening initially (i.e. a wider curve) and will also mean a similar high risk of "wrong lane" encounters.


2. Lower your body.
Yep, quick and easy to do.
In theory it should help . . . but in practice, not so much.
Might help Willemsen's lightweight rig just a touch, but for Haggis . . . the benefit would be tissue-paper-thin. Won't save him.


3. Body English / leaning in.
As Claude has said earlier, it is a good move to set up before reaching the corner, but not practical during the mid-corner emergency.


4. Dirt technique. Lotta power needed. And light weight.

True, on bitumen a rear wheel spinning 20% faster [than road speed] will deliver more traction than a non-slipping wheel : but as you yourself have said, it's not actually a practical choice (for a number of reasons).


5. Turning & spinning.
James Bond technique (or did I see it done by Indiana Jones's stunt man?).


Later, to add some levity, I might trot out a different list of 4 choices facing the "too-hot cornering" driver.
Trouble is, they're not even half-humorous once you're in the middle of the emergency.
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Old 08-09-2013, 06:31 AM   #159
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The so called tip over lines are real and yes fuzzy...but a lot of things are fuzzy. We can get into all kinds of discussion on this but the fact remains that the important thing is to practice. Feel is always better then words. The purpose of words are to help someone to gain enough knowledge to be able to practice with some type of goal in mind. Saying " okay here's your new sidecar outfit. Have fun and remember they handle funny so take it easy" is not doing that person any good nor the sport we love. Some can be word smart and dummer then a rock when it comes to applying things in the real world. None of us can really equate things above our own experience that accurately. Some equate things from their own experience but if the experience was based on bad knowledge then the info they relate isn't the best and the bar cannot be raised. We are all learning. Sharing and discussing experiences is a good thing for all of us.
There are some good sidecar jockeys on this forum. They may not all agree on all things and that is fine but the things said can still be positive food for thought for the whole.
Everything Scott just posted including the pictures was excellent. I tried earlier to describe in words some of that but as they say a picture is worth a thousand words. Understanding the dynamics of what a rig is doing when in a position such as the world champ pic posted is fine but the theories need to become a part of us so we can react without thinking . THAT is when planed actions become given reactions ..as said we can plan our actions but our reactions cannot be planned they just happen from experience.
Sprint cars (especially without wings) tend to 'bicycle' at times due to various factors. In other words they get up on two wheels. This is not that different than a sidecar wheel coming up in a way. Many times this happens due to track conditions or hitting the cushion wrong. The cushion is the built up dirt around the top of the track and in many cases running up there is by far the fast way around. It is also the place where the margin of error can be small. A common rookie mistake is to over correct when the car bicycles. Overcorrecting being turning the wheel too far to the right (we are going in left hand circles here). What happens? The car may come back down but the front wheels will steer the fence. The duh factor comes into play and typically the wheels will climb the fence and a simple tommy tip over will happen. I am talking about a situation where a little experience could have prevented an embarrassing situation. Not talking about a major crash here that is another story only talking about a rookie mistake which is common and can be avoided. In a similar vein over correcting a sidecar outfit that has lofted the sidecar wheel in not much different.
Sorry for rambling again..gotta get to work .
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Old 08-09-2013, 06:36 AM   #160
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Midnullarbor wrote in part:
>>While I can't say I positively enjoy being corrected over my errors . . . nevertheless I welcome you (or anyone) hitting me over the head and pointing out where I am wrong.
I'd rather be embarrassed and set right, than carry on naively being wrong.
<<

Great points. We all should be open to these types of things. Constructive criticism is not a bad thing. Criticism may or may not be accurate but it always, if presented in the right way, gives us a chance to think and possibly will allow each of us to gain from it.
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Old 08-09-2013, 07:48 AM   #161
claude
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Basic cornering technique thoughts

Basic Cornering technique:
(Street oriented for the most part)
1)Brake before entering the turn and do so in a straight line.
2) Stay out near the centerline looking for taking a late apex...see yellow line in picture.... ( click here:
http://www.modernracer.com/tips/properapex2.jpg )
Advanages to a late apex:
1) This will give you a better line of sight through the turn prior to committing to it. Is it a decreasing radius? Is there a road kill on the road in your line? Deer standing on the side of the road.? Bouncing ball with a small child chasing it?
2) A late apex will allow you to judge your speed according to your skill level and the outfit you are on and possibly avoid targets that loom ahead easier.
3) A late apex will also give you more 'wiggle room' on the exit as a safety factor. Crossing the centerline can bring evil things your way especially if you are unaware of what is coming up. Crossing the centerline can also lead you into an off camber road situation that can make matters worse if you have already gained more speed than you wanted to.
Simple techniques such as this ,if practiced early on, can lead to faster cornering speeds than tend to come naturally in time.
If you enter a turn at a speed you and your machine are comfortable with you can accelerate through the turn and still be in control. Acceleraring through the turn will also help decrease steering effort as the sidecar lags behind. Overcooking the entry into a blind corner is NOT the thing to do.It will cause frustration and a certain fear factor to develop or possibly a worse thing. Simple technique will allow for your skills to grow at a pace where they are not scary not Self defeating.
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Old 08-09-2013, 01:17 PM   #162
MILLENNIUM FALCON
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Ouch!

I Think this guy was going into the corner "too hot!"

http://www.youtube.com/watch?v=wgwjk8j5oug
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Old 08-09-2013, 04:33 PM   #163
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Ouch indeed.
For once, I won't say too much . . . but is that an unballasted outfit I see?
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Old 08-09-2013, 05:26 PM   #164
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Yes too hot I suppose and a with bare sidecar frame. wow. If you'll notice the sidecar barely got off the ground. He may have had more 'wiggle room' with experience and a better balanced outfit than what was shown which was zero. Too hot? Yes no doubt for what he was on and obviously for his lack of experience and judgment. Good example of being dumb actually. Hope he wasn't hurt.
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claude screwed with this post 08-09-2013 at 05:34 PM
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Old 08-09-2013, 07:00 PM   #165
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Ooops !!!!!!!!

Well I screwed one up this evening big time and I'm not sure how possibly tired in a hurry and going to fast 120 degree rt onto a freeway trying to lift chair with 220 pound buddy and dog. I think the car was up and I panicked and tried to get widder and slow down but too much rear brake and we slid ended up in the grass slid faster across two lanes of traffic luckily there was a hole and I gained control on the left shoulder.I think the whole deal was I'm out of experience panic.I washed bike up as we'd been off roadDBing when I got home and did a few rights in parking lot to check my lift off.
I will return to the scene of the crime tomorrow and fine the error of judgment.
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