How does tiller affect performance?

[loon]

I would expect it to all move at their own constant rate (ie with elliptical tiller, tips would start moving more than towards the handle, but handle also bends, just less, and all at the same rate until full draw) but apparently not - I saw a full draw picture of a heavy warbow draw partially, and it looked like all the bend was close to the handle... apparently because it wasn't at full draw? I would expect the bending at the handle to get worse with more draw or something. Maybe the leverage of the whole thing changes as the bow is drawn and gets bent? Should just look at videos of warbows with whippy-ish/elliptical tillers getting pulled...

Then there's all the weird frequency harmony stuff that I can't even. Bowstrings look ridiculous upon release on slow motion videos..

so inefficient energy transfer to the arrow makes handshock worse, but would it be possible to dry loose a bow with massive tips (somehow not breaking it) without feeling handshock if the limbs were perfectly timed?

[Selfbowman]

I suspect the limbs will come to rest in the same fashion they are bent during draw no matter what  the design is . In my opinion one consistent form of diminishing mass  will give the best performance. If the mass is not working its dead mass. You are depending on energy from another source such as in a catapult with a stiff limb . You have to counter weight a catapult if you don't want it to rock and bounce on release. This is the same as shock in a bow.  But I don't know everything for sure. Lol Arvin

[Marc St Louis]

   I think this is a good topic and I expect somewhat theoretical as I can't give prove of any of my own theories. That being said I feel the best tiller shape would be one that allowed the outer limbs to start moving first during the draw and allow the bend to progress inward during the drawing process until the last few inches where the near handle wood starts to bend. Most of us including myself are usually tillering for a desired shape so to some degree we ignore the progression of the bend. An Elliptical tiller will usually facilitate this pretty well. Circular tillers I feel are the biggest cause of handshock. Having only the outer limbs bending as the string returns to brace during the shot lowers the momentum of the limbs and gives the arrow a lot better control over the limb mass. The arrow needs to slow the tips down to extract the energy or else it will be lost to vibration.

I don't think it's possible to get that kind of tiller Steve unless you re-design the limbs to have more working wood in the outer limbs than the inner limbs and that would defeat the whole purpose.

[sleek]

Marc, I dont understand?

[JoJoDapyro]

The thought is good. But, If we think of different types of bows open up at different times. Horn bows, Magyars, Recurves, Static recurves and finally a straight limbed bow would all have the tips moving at different times. As well as all of these showing a difference in performance.

The turbo analogy actually works out well for working recurves. You get the initial lag in the draw, and have the up front power on release.

So, a working recurve opens last, and closes first. So think of it in terms of what flight bows shoot the best, straight limbs that have the tips moving last, or working recurves that have the tips moving first.

[JonW]

  I keep the last 10" or so stiff on most bows, it improves the stored energy. As for shock, the only bows I have ever gotten shock on were bows I used the gizmo on so I could rush and get done.Elliptical tillers will seldom ever be shocky.

Steve could you post a f/d pic of a bow that you describe here?

[PEARL DRUMS]

Most of my straight bows also have 10" of stiff tip. I always plan on 7-8", but it fades into the working limb and ends up closer to 10". I like it, cant speak for everybody.

[sleek]

The thought is good. But, If we think of different types of bows open up at different times. Horn bows, Magyars, Recurves, Static recurves and finally a straight limbed bow would all have the tips moving at different times. As well as all of these showing a difference in performance.

The turbo analogy actually works out well for working recurves. You get the initial lag in the draw, and have the up front power on release.

So, a working recurve opens last, and closes first. So think of it in terms of what flight bows shoot the best, straight limbs that have the tips moving last, or working recurves that have the tips moving first.

Jojo, flight bows are like rice butners. All horsepower and no torque.

[JoJoDapyro]

Jojo, flight bows are like rice butners. All horsepower and no torque.
[/quote]

Kinda funny, Ken Blocks Ford Focus is 600 HP and 650 Ft\LB of torque. 0-60 in 2 seconds flat.

[Badger]

   I think this is a good topic and I expect somewhat theoretical as I can't give prove of any of my own theories. That being said I feel the best tiller shape would be one that allowed the outer limbs to start moving first during the draw and allow the bend to progress inward during the drawing process until the last few inches where the near handle wood starts to bend. Most of us including myself are usually tillering for a desired shape so to some degree we ignore the progression of the bend. An Elliptical tiller will usually facilitate this pretty well. Circular tillers I feel are the biggest cause of handshock. Having only the outer limbs bending as the string returns to brace during the shot lowers the momentum of the limbs and gives the arrow a lot better control over the limb mass. The arrow needs to slow the tips down to extract the energy or else it will be lost to vibration.

I don't think it's possible to get that kind of tiller Steve unless you re-design the limbs to have more working wood in the outer limbs than the inner limbs and that would defeat the whole purpose.

  When I say outer limbs I am actually meaning outer mid limb, I keep the outer limbs almost stiff on most bows. I like to use the least amount of working limb I can get away with, but 90% of the time we still need most of the limb to avoid taking set. I asked a freind one time to build a glass bow using stiff outer limbs but fairly extreme tapers in the working area. This was on an r/d longbow. We used a reverse wedge in the tips and a power wedge near the fades with .008 tapers and the bow was extremely quick with 10 grain per pound arrows but only lasted for a few hundred shots. About 4" of reflex behind the back. It seemed to open up as I described, not a pretty tiller shape to look at.

[sleek]

Jojo, flight bows are like rice butners. All horsepower and no torque.

Kinda funny, Ken Blocks Ford Focus is 600 HP and 650 Ft\LB of torque. 0-60 in 2 seconds flat.
[/quote]

Ok fine, my point is still the same.

[BowEd]

Been making bows with 8 to 10 inches of stiff tips for some time now.Call em lever bows.Narrowed down and light as possible.Small handles[down to 6"] used with hardly any hand shock tell me it works.Reflexed or not.
There's the matter of mass weight distribution on these limbs.To get an extreme working recurve to hold up properly you need enough wood to handle it.Negating a bit of the extra energy from it as far as speed given to the arrow the way I see it.Not saying it's a bad design but just saying they are more touchy to tiller to get right.
Mild R/D profiles are the cats meow for bows though.Balancing the reflex given to not need so much wood to handle the strain.

[BowEd]

Badger...I have a friend who makes his own FG bows[he's made self bows too] and has adopted the stiffer tips design I shoot.Don't exactly understand all of the reverse wedges etc. used to get the job done but he likes the bow better and it is faster.Not so much reflex though as you described on his.Maybe a couple inches at the very most.

[JonW]

I'm a little slow. I can't wrap my head around an elliptical tiller with 10" stiff tips.

[Badger]

Badger...I have a friend who makes his own FG bows[he's made self bows too] and has adopted the stiffer tips design I shoot.Don't exactly understand all of the reverse wedges etc. used to get the job done but he likes the bow better and it is faster.Not so much reflex though as you described on his.Maybe a couple inches at the very most.

  The r/d bows get squirely once you get past about 2" reflex. The limbs will rock back and forth at brace. The soulution for that is less working limb. Actually less working limb solves a whole plethora of problems but it brings a few of its own, mostly just too much strain.