Movie bow critique

It is a fantasy bow and as such does not have to have any relationship to real bows.

The Egyptian angular bow was straight-limbed when strung.

I made a few bows just like it a few years ago and wrote an article about them for the Primitive Archer mag. No stacking even for a short ones and decent performance.

Adam

Adam,
While it does not bear a relationship to a historical bow (except possibly Naram Sin's), there is no reason that a deflex reflex as extreme as that would not work.

What did you use for materials?

Adam I've been told by several people about the bow and articles you wrote. Do you have any pics and stats of this bow available?

I made the bows in wood alone, but found it was difficult to keep the reflex intact. With a sinew backing the bows were quite easy to make, no horn was needed.

The bows had very high string tension at brace, so the stacking was not felt. The performance was about the same as for a good conventional bow.

Adam

That is a beauty. What is the width of the limbs?

Max. width was about 1 7/8in , tips 1/2", grip 1". Ntn length 46", 60lb @ 26".

Adam

Yes, it is very similar to the akkadian bow on the victory stele of Lagas. If I make a short hunting reflex bow, it would be similar to this beauty.

Adam, wow!

TZH

Adam how much acctual bend do you want in the center?

If I understand correctly, the limbs unfold into straight lines when drawn, and the center appears near triangular.

No, the limbs do not become straight at full draw. The grip is rigid, the reflex section close to grip become straighter (but does not open fully) and the upper 1/3 of limbs bends a little toward the strig. This makes the stresses about equal in the limbs at full draw. If the bow was bent mainly in the reflexed section to make the limbs straight, the stress would be too high there.

Adam

Adam; There has been some discussion in print that the shape you have made is the shape of some angular composites before shooting in-conditioning. This shape has eluded me in my reproductions, mostly because the existing artifacts do not have a large build up near the grip.

Interestingly enough, wood bows of the period, like the Tut bows 1300 BC, have exactly opposite shaping; as if you were to string this bow backwards. How do things get so turned around? -j-

I wonder the same about the things Jack has posted.


Adam I have begun fashioning something.

Here is the core being shaped, useing heat.

http://i24.photobucket.com/albums/c39/t ... esop-1.jpg



Here it is now after 3 courses of sinew.

http://i24.photobucket.com/albums/c39/t ... esop-2.jpg


I'm after the profile of some of these.

http://www.freebirdarchery.com/images/tut's_bows12.jpg

What cross section are you using? It looks as if the limbs are broad rather than thick.

The limbs are only 1-1/4" W

Yes, the design is an extreme case of deflex-reflex bows, but the whole limbs are working to equalize stress and to make it as short as possible. I would think the Egyptian bows before shooting, which induces string follow, would rather be less deflexed at grips?

I made a very short hornbow like this bows, to push the design. Unfortunately it broke (I should not have used yew for the core) and I lost interest. Maybe I will try again.

Thimo:

As I see it, your bow is a typical deflex grip - reflexed limbs design, an average case. The limbs are not reflexed enough actually for a sinewed bow, so I would expect too much follow. The grip seems to be bending (not too good), while the tips seem to be static (good). This is an r-d bow with static tips. If i were you, I'd try to maximize the draw length to force performance from this bow.

Adam

C'est tr?s beau ! Superbe design !
Please show us the bow when unstrung !

This is the bow unstrung. I am not sure if this bow can be discussed on this forum.

Adam

No doubt, this bow is a beauty.
What?s the source of this design?
Adam, have you done any chrono-tests with it.
I?m, as Jack, thinking about the design, cause it is the opposite design of the angular bows. I could imagine that the hard deflex is cancelling out the reflex of the limbs. Maybe this bow would perform better with a softer deflex and recurves. It would be interesting to compare the performance of this bow with a Native American double-curved plains- bow.

Michael

This is a way to get a long draw from a short bow. What I see is a handle that is few inch in front of bow. The handle set back gives long draw with short draw length. The bow is few inch closer to archer than the handle is. If you draw a line from limb to limb without the handle set back you get a short ordinarier set bow.
This is what i see, what the Egypt did I dont know.

That bow looks "interesting" unstrung.


Adam I'm not sure I understood your comments on why I may not be able to fashion mine into the right design.

Already (day 3) the sinew is causing added reflex as it cures.

http://i24.photobucket.com/albums/c39/t ... horus1.jpg

Redhorse, you are right, this is obvious.
I asked for the performance and thought about to enforce it.
Like everything a bow is a kind of "closed system", if you enforce something to get an advantage( the longer draw with a kind of short bow) the performance could suffer.
I would also like to compare this design with an almost straight( maybe with a little setback in the grip) short bow, like the Plains- Indians did.

Michael

Thimo:

I meant your bow does not have enough reflex in the arms without sinew. Sinew will add reflex, but later the arms will open too much in use. Such bow should have at least 2" total reflex without sinew (I am assuming the bow is about 48" ntn or so). It would then reflex further with sinew, but in use return to it s former reflexed position for better performance.

Redbow, the bow's limbs start very close to grip, closer than in typical deflex bows. This gives the bow more string tension at brace and then very high early draw weight. This in turn makes the bow feel as if it a longer bow. The idea here is to make the shortest non-stacking bow possible in wood or wood/sinew.

It is not the same as a small bow with a rigid forward grip. A bow like that would have in effect shorter arms and its performance would be poor.

Adam

Adam; how was the angle in the grip achieved? Joined ? steamed? -j-

Adam it is 52" between the nocks.

The idea here is to make the shortest non-stacking bow possible in wood or wood/sinew.

Could that be because the longer bow arm length before the bow comes to that point it starts to stack?
If you draw that bow 4 inch longer, will it stack?
What string angle does it have at full draw?

I usually made these bows by splicing limbs (steam-bent or laminated) to a natuarlly-curved piece for the grip.

Yes, the bows will stack eventually, depending on their ntn length, but I never tried to pull beyond 28" for bows up to 51-2". I have no idea about the string angle. The article appeared in Jan. 2000 issue.

Adam

It seems to be two different bows ?
The shape of the grip is different on the two pictures and should be the same ?

Anyway this is an amazing design.
Did you wrap the splices?
V, W, or Z splices ?

Adam Karpowicz wrote:

Max. width was about 1 7/8in , tips 1/2", grip 1". Ntn length 46", 60lb @ 26".

Adam

It's surprising that these short and even almost 2 " wide limbs can stand so much strength at this draw length.
And that the limbs keep this shape without sinew.
Maybe when laminated but steam bent ! ?

I guess the actual draw length is something like 3" shorter because of forward grip ?

Yes, you are right, the two bows are different. The top one is 60lb-er - white oak core, osage belly, sinew backed. The bottom is a hickory/osage laminate around 50lb (as I remember, I do not have it any more).

I always use V-splices, not wrapped. Sinew backing helps to keep the reflex, but wood laminate works too.

Adam

sorry, I thought we?re talking about selfbows. To keep the shape of such a bow as a lamination should be no greater problem. Well done the glueline will do the job.

If the drawweight is high at the braceheight it means that you need a lot of energy for to brace the bow. Almost the whole amount of this energy remains unused just when the arrow has left the string?

The contrary would mean to make a design with a drawweight nearly 0 at the braceheight, so almost the full amount of the drawweight is used?

I?m not sure, but I can remember that in the TBB?s we?ve had a discussion about that topic?

Michael

The energy stored in bows' reflex is not unused. It is manifested in more energy available to the arrow at the beginning of draw, as the "hump" in the force-draw curve. The efficlency of bows is a different matter.

Adam

Adam your bows look a awful lot like the Tut bows ,witch are horn bows .Have you ever tried to make a horn bow in this style?

Thimo how is your bow coming along?

"Thimo how is your bow coming along?"


I had it it the beginning working fine. Then abnormal set kept taking place at the handle area. Finally I unwrapped some of the barck to discover a nasty fracture there.

I am currently seasoning more staves to try again. This time I will use horn strips on the belly and more sinew layers on the back, AND make certain all is in proper working condition before decoration.

Ah, well. Live and learn.