Force draw curve.

[bigbob]

Thought I would post this force draw graph of the deflex /reflex I made recently. Only managed 5 shots through the chrono and speed was just a tad lower than I thought it might have been which is still very respectable for an all wood core, but as I was using fingers the figures are a bit rubbery as might be observed by the variation in FPS obtained. Arrow used was bare shaft carbon weighing close to the 540 g mark keeping the 9g per # draw weight ratio to arrow weight. D/length was approx 30'' The riser is cut to within 1/16'' of centre but with arrow plate would be around 1/8''. The curve shows how it has a very even and smooth draw right through the draw out to 31'.' Grey beard was going to do an efficiency on the graph but I forgot to give him the graph.This bow is available for any interested persons. It will come with a new Astroflite string by Wallace Woods, a string keeper, and vinyl bow sock, together with 12 months written warranty. Pm me if interested.
Duh, forgot to ad chrono speeds. 1---188fps; 2---186fps; 3--- 191fps; 4---188fps; 5--- 192fps. These figures highlight the need for a 'shooting machine' with mechanical release which I part built about 3 months ago and never completed.

[Fanto]

I know not everyone likes to talk about arrow speed, but Its a useful piece of information about the bow when taken into account along with smoothness of draw, queitness, lack of handshock etc, so I did a comparison before I ordered a bow and the speeds youre getting compare favourably with most top notch bowyers, love your work

cheers

[bigbob]

Knowing how picky you are with your bows and some of the ones i've seen you post, I'm more than flattered by your kind words Fanto .Bear in mind though that the speeds listed are with bare shaft and 'somewhere' around 30'' draw which is the criteria most US makers use.A heavier wood would drag the speed down but add to the kinetic energy and more 'stopping' power.

[Goatchaser]

still very respectable results Bob I'd be happy.

[greybeard]

Hi Bob,

The chrono results are quite impressive, it would be interesting to see the difference using fletched arrows with the bow drawn to 28".

I prefer 'real world' situations.

Daryl.

[bigbob]

still very respectable results Bob I'd be happy.
Thanks Chief.

Hi Bob,

The chrono results are quite impressive, it would be interesting to see the difference using fletched arrows with the bow drawn to 28".

I prefer 'real world' situations.

Daryl.

We have been discussing this agenda at the shoots Daryl and as I said there because people are to extrapolate the data by comparison then I have to play by their rules. still when I get a moment I will try a 'normal' fletched arrow and post the speeds obtained by that process.

[daniel boon]

Bob, that's no slouch,seems plenty fast enough to me. Well done.
Cheers Dan

[Fanto]

hey bob

no worries!

if you go heavier and slower with arrows, you'll get no change in kinetic energy but go up in momentum.

kinetic energy was proven by Ed Ashby to have no detectable correlation with arrow pentration which is in total contradiction with much of the archery worlds ideas notably manufacturers. this is because in calculating kinetic energy, velocity has a much greater impact than arrow mass. with momentum it's the opposite, arrow mass has a bigger impact on the momentum number, and you an graph penetration against momentum, and find that as one increases, the other does too.

as for me, my 500 odd grain arrows pass through the goats and continue at a barely reduced speed so I don't need any more science just more hunting time!!

[greybeard]

still very respectable results Bob I'd be happy.
Thanks Chief.

Hi Bob,

The chrono results are quite impressive, it would be interesting to see the difference using fletched arrows with the bow drawn to 28".

I prefer 'real world' situations.

Daryl.

We have been discussing this agenda at the shoots Daryl and as I said there because people are to extrapolate the data by comparison then I have to play by their rules. still when I get a moment I will try a 'normal' fletched arrow and post the speeds obtained by that process.

Bob,

Tests on compound bows are carried out using a 30" draw length whereas for conventional bows a 28" draw length is used.

As I have pointed out in previous posts I prefer to use the D L P P with in house testing as this gets around the issue of risers having different depths.

I may be out of step with the manufacturers method of testing but at least the D L P P is a constant measure.

Daryl.

[GrahameA]

Hi Bob.

... chrono speeds. 1---188fps; 2---186fps; 3--- 191fps; 4---188fps; 5--- 192fps. These figures highlight the need for a 'shooting machine' with mechanical release ...

1---188fps
2---186fps
3---191fps
4---188fps
5---192fps

Mean 189 +/- 3fps
+/- 1.5% variation

Yes, it would be better to getter a more consistent velocity however, I would not be complaining about getting those results. If you want better results to work with with shoot more arrows and then go with a statistically better result.

[bigbob]

thanks Fanto, Daryl and Grahame, all incoming info has been collected and sent to central nervous system and cerebral centre for processing I do appreciate your collective wisdom.

[rodlonq]

Gidday Bob,

Good numbers there. Your bow looks and performs very well, good job mate.

AMO draw length is a constant measure as well, but with consideration for a standard depth of riser and regardless of the actual depth of riser. The below is copied directly from the AMO standard.

"AMO Draw Length is the distance to Pivot Point plus 1 3/4”. This establishes a
constant when compared to the variations of profile of the back
of bows. Thus - 26 1/4” from Pivot Point is equivalent to 28” draw length and is
the draw length at which manufacturers weight and mark conventional bows."

I dont understand the reason for it, but it makes little difference where the datum point is if everyone uses the same datum point. The AMO definition probably has some relationship to arrow length. It is understandable that a person using an AMO 28" draw length could use an arrow with 28" to the back of the point (field point - not broadhead) regardless of the actual depth of the riser. The alternative measurement of 26.25" DLPP is not so easily related to arrow length even though it is more intuitive - or is it .

Cheers..... Rod

[greybeard]

Gidday Bob,

I dont understand the reason for it, but it makes little difference where the datum point is if everyone uses the same datum point. The AMO definition probably has some relationship to arrow length. It is understandable that a person using an AMO 28" draw length could use an arrow with 28" to the back of the point (field point - not broadhead) regardless of the actual depth of the riser. The alternative measurement of 26.25" DLPP is not so easily related to arrow length even though it is more intuitive - or is it .

Cheers..... Rod

I believe that in the early days bows were rated and marked at their true draw length i.e. dlpp. This method probably predates fibreglass and is relevant to all wood bows that were made to a specific [maximum] safe draw length.

When glass laminated bows were introduced a considerably longer, safe draw length could be obtained but the bow were still marked in the old system.

Apparently this caused confusion because archers who did not understand the system were ordering arrows to the length shown on the bow.

To overcome this the AMO standard of 28” was introduced to resolve the issue.

Daryl.

[rodlonq]

Thanks for the information Daryl. It all makes more sense now.

Cheers..... Rod