Boo Yew RD

[DC]

Very nice!

What is brace height, measured from belly? And how thick the handle is? Would it be possible to get draw force measurements as a numerical table? I would like to make some calculations, for example efficiency. And, if possible, please measure the speed with light and heavy arrows too, for virtual mass calculations. How much the bow took set? What is difference in reflex with just un-braced and rested bow? Did you shoot with machine or finger release? Could you make "bow profile table", so measure reflex measured from the back of bow one or two inch intervals? And what is the mass of bow? What string, mass and strand count?

What chrono, measured in artificial or natural sun light?

I do not doubt your results, quite the opposite. You know what you do, the bow is just great and it has very good draw force curve. I just want to calculate some numerical values to support your results. As far I know, this is the first "200+ fps with 10 grain per lbs arrow and 28 inch draw" with any kind of natural material bow, so it should be documented well.

And this bow deserves better photos...

Thank you and congratulations!

BH-6"
Handle-1 1/2"
Speed 320 grain-224fps and 450 grain-196-198. I'm getting different readings from the two chronos.

Reflex rested 5 7/8". Just unbraced 5 3/8"-5 7/16 depending on how fast  measured. It recovers full reflex in less than 15 minutes.
I made a profile table but I measured to the belly. I'll redo it. There is a marked difference between the limbs.
Bow weighs 422 grams no string
String is 6 strand D-97 Flemish 42 grains
Caldwell and Chrony artificial light

I just checked the DW and it was 41 today. I shot a 409 grain arrow and got 204fps. It's never the same. Up and down by 4-5 fps from one day to the next.

It will have to wait for a better photographer
Thank you.

I'll get back to you with more info.

[DC]

No I didn't, I measured to the back. Here ya go

             Bottom                Top
2              5 7/8                5 13/16
4              6 1/16              5 7/8
6              6 1/4                5 13/16
8              6 3/8                6
10            6 1/2                6
12            6 9/16              6
14            6 5/8                5 7/8
16            6 9/16              5 3/4
18            6 7/16              5 5/8
20            6 1/4                5 7/16
22            6                      4 7/8
24            5 5/8                4 11/16
26            4 7/8                4
28            3 3/4                3 1/4

Hope this is of some use. Let me know what you discover. I've got the numbers written down so if any of these don't make sense I can check them. I've been concerned that the top limb is weakening but I'm hopefully thinking that what I'm seeing is that the bottom limb has so much more reflex to start. The speed hasn't plummeted so maybe it's OK. I'm probably pulling it weird on the tree.

[sleek]

If you have the materials and the mind to do it you should build another one identical in profile. The ONLY difference should be that instead of 6 1/8" of reflex, only put in 5 1/2" inches. This bow should take 0 set and be even faster than the one you got now.

Sleek - if he did the same as a trilam ... gluing in deflex before pulling in reflex what would you feel the outcome would be?

The short answer is, anything you change about the build will negate those exact reflex numbers given

[Tuomo]

Thank you for the additional information! I really appreciate it.

I would prefer numerical force-draw table, it is more accurate. If possible, please measure draw force one inch increments. And, please see this, my tiny test:

https://www.tapatalk.com/groups/paleoplanet69529/one-bow-two-draw-force-curves-t66460.html

So, there is a difference between maximum value and rested value in draw force. It is important to know, how you measure the draw force in force-draw measurements. Stored energy should be calculate as accurately as possible, because with it the efficiency can be calculated accurately also.

[DC]

There is one thing that is important when comparing 10ggp performance to glass bow tests in order to compare apples to apples........

Alan,
If Don is fairly close to AMO standards, then one big difference between his bow and most glass bows tested is Dons 5.5" brace height.

What is your opinion about possible gains or losses a comparable glass bow would exhibit  at such a low brace?

If I understand this right, the 5.5” brace height on the force-draw curve is measured from the back of the bow?  It is 4” from the belly side of the bow handle?

I would love to see this bow flight shot at the Salt Flats!  The force-draw curve is amazing!

Willie,
It depends on the bow design and the properties of the string. Usually bow efficiency drops at very low brace heights. Energy storage increases, but efficiency drops and often counteracts this. A string made of very high tensile stiffness material helps the bow tolerate a lower brace height.

Alan

Alan, thanks for taking a look. I really appreciate your input. The bow seems to have risen to 41#. I'll have to remember to do a draw weight every time I do a test. I'm finding it difficult to make accurate measurements. It would be nice to see how it's really done. Do you have any links that might show me something? When you say the FDC is amazing what exactly are you looking at? I don't see a bunch of difference between this and my other bows. Does a small difference make a big difference? The one think that stands out to me with this one is how heavy it is to brace. If I had to guess(because I don't have a lot of heavier bow experience) I would say it's like bracing a 50-60# bow.

[DC]

Thank you for the additional information! I really appreciate it.

I would prefer numerical force-draw table, it is more accurate. If possible, please measure draw force one inch increments. And, please see this, my tiny test:

https://www.tapatalk.com/groups/paleoplanet69529/one-bow-two-draw-force-curves-t66460.html

So, there is a difference between maximum value and rested value in draw force. It is important to know, how you measure the draw force in force-draw measurements. Stored energy should be calculate as accurately as possible, because with it the efficiency can be calculated accurately also.

Here's the numbers. You'll notice that it goes to 42.65# this morning. I tested it with a 421 grain arrow and only got 199 and 200 fps on the two chronos. This seems to change daily. I'm starting to doubt myself here

6=0
7=4.73
8=8.26
9=10.91
10=13.33
11=15.32
12=17.19
13=19.06
14=20.72
15=22.37
16=23.91
17=25.57
18=27.11
19=28.54
20=30.20
21=31.74
22=33.25
23=34.94
24=36.37
25=38.02
26=39.46
27=41.80
28=42.65

Badger, I have to amend that 35@24 to 35@23. Not looking so good now. Could it gain draw weight and lose speed?

[Badger]

DC, I wouldn't even worry about those small losses, you are still way up there.

[bradsmith2010]

congratulations DC,, I knew you could do it,, just enjoy and proceed with having fun,,we are all proud of you and your bow,,have the best bow making day ever,,

[willie]

Could it gain draw weight and lose speed?

sometimes a weight measured on the way up is not the same as if it is measured on the way down.

[DC]

Maybe not related but I think one of the things that's messing with me is parallax. From where I stand to pull the tree brace height is right on but once the string gets down to 28" the angle I'm looking at makes 27 1/2" look like 28". Not a problem when just tillering but when one measurement affects the next one it starts to add up. If I pull the bow to what looks like 28" and is actually 27 1/2 it can make the bow look lighter by 2-3 pounds. So now I choose an arrow based on the lighter weight. So now the arrow may be 9 gpp instead if 10. Then I shoot it though the machine which is actually a 28" draw. So now I've got a 42#(instead of the 40#) shooting a 9 gpp arrow. Presto, the chrono shows 8-10 fps faster than the bow is. It's this kind of crap I've got to sort out before I go much further.

[PatM]

Wood fluctuates.  That's just how it is.

[DC]

Wood fluctuates.  That's just how it is.

Yeah, it's kind of frustrating to put your pride and joy out for the world to see and then two days later you're back tracking. Oh well, ain't the first time I've looked foolish, won't be the last

[sleek]

Wood fluctuates.  That's just how it is.

Yeah, it's kind of frustrating to put your pride and joy out for the world to see and then two days later you're back tracking. Oh well, ain't the first time I've looked foolish, won't be the last

Its in the eye of the beholder. If you look foolish to anyone on here, the fool is the observer. Not many on here can get within 30 fps of you. You are making bows that inspire people.

[DC]

Thanks Sleek, I remember a few years back you posted a bow that shot 200fps. I think that's where it started. Don't know whether t thank you or not

[sleek]

Yeah, that was a good time. I dont remember what the exact arrow weight was, but I do recall the arrows were close but not quite 10gpp. It was like 8 I believe. So you got me beat by miles.

Edit to add: But, that was also with a 26 inch draw. And, for a long time now, I have been arguing that 10gpp is not accurate for anything other than 28 inches. You must drop grains as you drop draw length.