Interesting "Backward" Bows and Crossbows

[Dr. Tad Hussein Winslow]

What do you think of these bows / Xbows with "negative" brace heights ("reverse string draw technology"):

1. Gearhead Archery Crossbow:
http://www.youtube.com/watch?v=nWOtNy-L5IQ
and
http://www.youtube.com/watch?v=kTDfxW8YQLY&feature=related


2. Horton Vision 175 Crossbow:
http://www.hortonarchery.com/


3. Gearhead Archery Bow Vertical / Normal Compound Bow:
http://www.youtube.com/watch?v=Z0lQUYnKNnU&feature=related
and
http://www.youtube.com/watch?v=M8syqM06W7o&feature=related

4. Unknown Origin:
http://www.youtube.com/watch?v=x-W3jLb3HTc&feature=related

I've become extremely interested in this design. The beauty of it that's it's win-win-win: (1) The much longer powerstroke gives you much more power for the draw weight; or to put another way, the same power for much lower draw weight; so much so that you can hand cock the crossbow (roughly 80 lbs in the case of the Gearhead), and still generate a ton of arrow speed - no need for ropes, cranks, etc. (2) On the crossbows, it's makes it far less front heavy than other crossbows, which is an important thing for balance/handling in the field - my Tac-10 is the smaller-lighter of the two PSEs, and it's extremely front-heavy and unweildy, even with it's very small bow design; and (3) on the manual/vertical bow, the wheels are supposed to eliminate human error /wobbling or some such, for greater accuracy.

I'm kicking myself now for buying the PSE instead of jumping straight to this more advanced design - anyone know of a *drawback* to these? Hitting eggs with a field expedient rest from 50 yards in the wind with an xbow that you can hand-cock is might impressive stuff. I'm also interested in the V-bow/manual bow as well.

Was planning to get another Liberty, but I'm gonna check out and try to shoot a Gearhead instead. What about the Horton - they've actually been sold in fair numbers - anyone have one or know someone who does or did, and have a report? There was one of those Hortons at H&H back before deer season started, and even well into October, but it's gone now.

 

[doctorjj]

How is it a longer power stroke? Draw length is draw length. Brace height is brace height. Force draw curve is force draw curve.

Edit: Was this thread always in the classifieds section or was this some weird glitch in the matrix and it moved??? Sorry about posting here if it was in the classifieds all along. Feel free to move or delete my posts.

 

[Dr. Tad Hussein Winslow]

In a tangentially-related topic, how about the "SlingBow"?

http://www.youtube.com/watch?v=NshtEe_TsRA&feature=related

Fits in your fanny pack and it capable of taking big game, if you get pretty close.

 

[Dr. Tad Hussein Winslow]

How is it a longer power stroke? Draw length is draw length. Brace height is brace height. Force draw curve is force draw curve.

Well on the actual bow, I'm not sure the power stroke is longer, but on the crossbows, it's a longer power stroke because it IS a longer draw length. The draw length is longer because the string is further away from the cocking point (full draw) before being drawn. It simply is able to travel a longer distance before cocking (full draw); hence the longer power stroke. Just switch the bow backward and pull the string the wrong way, and voila - instantly more power with the exact same bow / draw weight. Oh, come to think of it -- the better way to explain it is, it's because you're pulling it PAST where the grip would normally be on the 'crossbow bow', giving you a longer draw length. You can't do that the other way - you just would have to make the bow longer, which makes it even more heavy and unweildy.

But on the bow, I suppose the draw length / power stroke is not longer, from the looks of it. On the bow, draw length IS draw length, as you say, and there's no way to make your arms longer, so I don't think the theory is gonna hold true on the regular bow... Well, unless you designed it like the one in that last video, where the string is in front of your hand, so that you have to reach further to grab it - same arm length, and same draw length *as draw length is ordinarily measured*, but more actual true draw length becuase the string is in front of your hand.

See, the 4th video there? It's actually the same concept as the Gearhead and Horton crossbows, but different from the Gearhead bow - the string is in front of the hand at the beginning of your draw. So your "true" draw length (if you will) is (a) normal draw length, plus (b) amount of brace height (to the grip), plus (c) amount of length by which the string is out in front of the grip.

 

[Dr. Tad Hussein Winslow]

Hold up a sec. The limbs are NOT backward on the Gearhead crossbow, like they are on the Horton, but the string goes forward around the "wheels" before it comes backward.

Actually, I think it's the case that ONLY the 4th video - the home design - does as I described in the previous post and in post #1, to give you true actual increased draw length/power stroke. But if you look at the Horton, it does NOT do this, now that you mention it - it's cocked into place before it reaches the riser, giving you the same (or actually less) draw length.

So scratch what I said about the Horton. The home build there is definitely where it's at in terms of what interests me the most - very light weight but good/adequate power. The Gearhead design is really completely different. The limbs are NOT backward like on the #4 video, but they claim to gain more powerstroke - hold on a sec; more research is needed - good points doctorjj...

By the way, that 4th video is a "regular bow" but with a cock-open device - very interesting.

 

[cooljeff]

uhm, maybe I'm missing this. But what exactly is for sale here?

 

[Dr. Tad Hussein Winslow]

Ya know, doctorjj, if you study the Gearhead crossbow video and design, it actually does do what I'm describing, but in a different/roundabout way - the string goes from the front backward toward you (the shooter) when drawn. But unlike the Horton, it goes PAST the "end" of the bow - the spot where the riser *would be* if the bow was backward like the Horton and the home build, and then goes on back a ways before being cocked - so you do effectively get a longer power stroke and draw length *for* the length of the bow and weight of the limbs - just by virtue of the string going past where it would normally stop at the *back* of the bow and going forward to the front of the bow - longer power stroke for the same bow length & weight. Evidently this is how they get a 350 grain arrow to launch at 325 fps from a 75 lb bow! If they're not fibbing, this is actual arrow speed, not "IBO" speed.

cooljeff, sorry I just realized I posted in the wrong forum accidentally - somehow ended up here but thougth I was in Hunting & Fishing?

 

[cooljeff]

Ya know, doctorjj, if you study the Gearhead crossbow video and design, it actually does do what I'm describing, but in a different/roundabout way - the string goes from the front backward toward you (the shooter) when drawn. But unlike the Horton, it goes PAST the "end" of the bow - the spot where the riser *would be* if the bow was backward like the Horton and the home build, and then goes on back a ways before being cocked - so you do effectively get a longer power stroke and draw length *for* the size and weight of the limbs - just by virtue of the string going past where it would normally stop at the *back* of the bow and going forward to the front of the bow - longer power stroke for the same bow length & weight. Evidently this is how they get a 350 grain arrow to launch at 325 fps from a 75 lb bow! If they're not fibbing, this is actual arrow speed, not "IBO" speed.

cooljeff, I don't know what's for sale (other than the Horton). But I sure hope they are for sale somewhere - certainly that's their idea at Gearhead - to sell bows.

I was only checking because I think you posted this in the classifieds. And was just wondering what you were selling?

 

[Dr. Tad Hussein Winslow]

Here, found another one - the "Skorpyd" crossbow, which is just like the home build in video 4 - backward bow and drawing past the riser.

http://www.youtube.com/watch?v=cgGqelpeBRc&feature=related

They're claiming it's the fastest bow on the market, launching a 400 gr arrow @ 425 fps with a 20" draw length, with 160 ft.-lbs of kinetic energy! So I guess there really is something to this design.

http://www.youtube.com/watch?v=MRZMQnSpwtA&feature=related



I'm not sure of the better design, the Gearheard or the Skorpyd, but I'd guess the Gearhead - getting over 300 fps with a 75 lb draw is more impressive then getting 425 fps with a 165 lb draw. I'd like to shoot them and price them both, testing for balance, accuracy, shootability, durability/quality, and then decide.

 

[Dr. Tad Hussein Winslow]

Oh crap, I thought I was in the Hunting Forum- could a mod please move this for me? Thanks and sorry.