Post by: Shredd on April 13, 2021, 01:10:20 AM
https://www.youtube.com/watch?v=teMO9oCl4YE
Post by: Mad Max on April 13, 2021, 08:13:21 AM
Post by: Roy from Pa on April 13, 2021, 09:06:54 AM
Guess I'm old fashion....
Post by: Flem on April 13, 2021, 10:08:53 AM
Post by: Shredd on April 13, 2021, 03:05:25 PM
I dunno...
Guess I'm old fashion....
Naw... Your just Old... :laughing:
Post by: Roy from Pa on April 13, 2021, 03:12:31 PM
Post by: Pat B on April 13, 2021, 04:32:43 PM
Post by: avcase on April 13, 2021, 06:50:36 PM
It would take a little programming, but the device could be much more automated, along with generation of various stats like total stored energy, stored energy to pounds draw, etc. There are even blue-tooth add-one that you could use to beam the results to your phone.
Thanks for sharing this
Alan
Post by: Mad Max on April 13, 2021, 08:12:49 PM
Post by: ztontonz on April 15, 2021, 05:39:30 PM
Post by: Shredd on April 15, 2021, 08:28:49 PM
Post by: ztontonz on April 16, 2021, 03:30:29 PM
Post by: Shredd on April 16, 2021, 08:29:28 PM
Post by: Mad Max on May 19, 2021, 08:35:10 AM
Post by: williwaw on May 19, 2021, 01:01:42 PM
Post by: Shredd on May 19, 2021, 01:06:04 PM
Post by: Roy from Pa on May 19, 2021, 04:07:00 PM
Post by: Flem on May 19, 2021, 04:46:08 PM
Post by: jess stuart on May 19, 2021, 05:43:55 PM
Max is it one of your statics?.
Post by: Shredd on May 19, 2021, 06:26:23 PM
We are trying to learn something here and you got to make ignorant remarks like that?
What you'll learn is how to make an inaccurate DFC... :thumbsup:
Post by: Mad Max on May 19, 2021, 06:29:27 PM
Post by: Shredd on May 19, 2021, 07:35:06 PM
My statement was not ignorant... It was pure, honest and true... Hope Y'all realize that...
Post by: Mad Max on May 19, 2021, 07:58:41 PM
Did you READ any of the Info. on the bow?
Does this bow DFC really need less than a half pound measurement?
Post by: Mad Max on May 19, 2021, 08:04:24 PM
I guess it's OK for 17th/19th Century
Post by: Shredd on May 19, 2021, 08:09:10 PM
2 Hinges about 12" long :laughing:
Did you READ any of the Info. on the bow?
Does this bow DFC really need less than a half pound measurement?
Got it... :laughing:
Yes... Saw this a while back and I think we discussed this... Impressive...
It all depends if you want to look at a curve or see what the bow is really doing through the numbers... I usually look at the numbers more than the curve and in this example there are no true numbers to look at...
Post by: Shredd on May 19, 2021, 08:15:10 PM
Post by: Longcruise on May 19, 2021, 08:48:03 PM
Post by: Mad Max on May 19, 2021, 09:02:51 PM
I like the numbers :thumbsup:
Post by: Roy from Pa on May 19, 2021, 09:26:26 PM
Post by: Mad Max on May 19, 2021, 09:38:42 PM
Post by: onetone on May 20, 2021, 12:43:54 AM
Post by: Roy from Pa on May 20, 2021, 06:42:03 AM
It has to alter it somewhat.
Or is there a standard brace height for which to start with?
And Rich, I was only messing with ya to fire ya up:)
Post by: Mad Max on May 20, 2021, 07:22:43 AM
Interesting article Max. Some useful info there for them that build RCs. Hard to imagine such craft developed before there were DFC graphics.:thumbsup:
What does the FPS on the arrow work out to be with a 820 grain arrow?
82#@32"--191FPS with 1230 grain arrow--3 under release
Post by: mmattockx on May 20, 2021, 10:31:26 AM
Why is the DFC line not going threw the squares :dunno:
If the curve is drawn by a spreadsheet using a curve fitting function it won't hit all of the data points.
What does the FPS on the arrow work out to be with a 820 grain arrow?
82#@32"--191FPS with 1230 grain arrow--3 under release
If you assume no loss of efficiency with the lighter arrow then speed with the 820gr arrow would be 234fps. If you assume a 10% loss of efficiency then the speed would be 221fps.
Mark
Post by: Shredd on May 20, 2021, 11:18:01 AM
Roy... First off you will never, never find the answer to your questions with a DFC such as this... Now if you had an accurate DFC you could find the answer to your questions... When you look at both curves with one being a lower brace height than the other you will not see a difference in curves.... If you were to overlap those curves you may see a subtle difference... When you look at the numbers you will definitely see a difference...The one with the lower brace height will have slightly higher numbers at the bottom of the curve and and lower numbers at the top of the curve...
There is no standard brace height... Just use the brace at what you choose to shoot your bow...
Yep... I was fired up a little... :tongue: :laughing: But I was looking at your statement as more or less ignorant of what a dfc is all about... ;) :)
I will say this about DFC's... People often say that there is more stored energy underneath the belly of that curve... If this was true a hill style bow with a relatively flat dfc would have no energy at all... I believe there should be a better way of defining it... If you have a hill style and a high performance recurve and they both weigh 50# they have the same potential... It's how they deliver that potential... Like a 500 hp deisel against a 500 hp gas race engine... One is gonna get down the track a lot quicker and one will pull better... So I don't think the limbs are storing more energy... I think it's how the limbs deliver the energy stored... It's like two pitchers of equal build and strength and one throws a 90mph fast ball and the other only 85 mph.... And like I have said before... I have seen a better looking dfc that shoots a slower arrow of the same bow design... There are many other factors involved than just a dfc...
Post by: Roy from Pa on May 20, 2021, 12:52:49 PM
:wavey:
Post by: Shredd on May 20, 2021, 12:56:11 PM
Post by: Mad Max on May 20, 2021, 02:20:11 PM
"It seems to me that you can show 100 people a beautiful flower garden and one out that 100 will dig their hands deep down in the soil and say, "See, this is shit and it is everywhere.!!" :tongue:
Post by: Roy from Pa on May 20, 2021, 03:28:05 PM
:laughing:
Post by: mmattockx on May 20, 2021, 04:48:43 PM
If you take into account that those look like very heavy limbs I think you may be disappointed with the arrow speed of a lighter arrow especially at 28" draw...
I agree. Those limbs do look very heavy so their max dryfire arrow weight is probably surprisingly high. That 32" draw is a huge help in getting better performance, I am sure a 28" draw would really gut the numbers.
Mark
Post by: Shredd on May 20, 2021, 04:58:59 PM
I said the bow was Impressive... What do you want?? :laughing:
Post by: Mad Max on May 20, 2021, 05:31:51 PM
Post by: Mad Max on May 20, 2021, 05:38:49 PM
If you take into account that those look like very heavy limbs I think you may be disappointed with the arrow speed of a lighter arrow especially at 28" draw...
I agree. Those limbs do look very heavy so their max dryfire arrow weight is probably surprisingly high. That 32" draw is a huge help in getting better performance, I am sure a 28" draw would really gut the numbers.
Mark
Yep
" It will not shoot a light or medium weight arrow very fast but will not be slowed down much by launching a heavy arrow either. This makes the bow well suited for anything that required the use of heavy arrows: warfare and large game hunting. Heavy arrows offer a high degree of penetration through layers of protection (war), increased damage by heavy broadheads (hunting) and increased immobilizing effect due to the arrow's weight (both). Focusing on high damage with large projectiles, it is unlikely to ever win a flight shooting competition against, say, Ottoman or Korean style bows that are primarily built with speed in mind. But when a Manchu arrow strikes within its effective range, it strikes with greater force."
Post by: williwaw on May 20, 2021, 05:58:21 PM
People often say that there is more stored energy underneath the belly of that curve... If this was true a hill style bow with a relatively flat dfc would have no energy at all... I believe there should be a better way of defining it... If you have a hill style and a high performance recurve and they both weigh 50# they have the same potential... It's how they deliver that potential...
shredd, when considering stored energy, my understanding of "area under the curve" includes the red area in the pic below. Do you mean something different when you say a hill style "would have no energy at all"?
[ You are not allowed to view attachments ]
Post by: avcase on May 20, 2021, 06:06:46 PM
One more issue. The string used is a pretty heavy B50 string. The energy lost to propelling the string and energy lost due to the elasticity of the string alone will add up to more than a few percent dynamic efficiency loss.
Alan
Post by: Mad Max on May 20, 2021, 06:23:44 PM
It may be that you can't get a accurate DFC on a Horn Bow.
The sinew keeps stretching and horn compressing when drawing to each inch for the DFC and the B50 also.
Post by: avcase on May 20, 2021, 08:18:46 PM
At our flight shoot events, we have to verify the draw weight of each bow just prior to each round of shooting. I have had a 45# bow gain 5-6# in just 3-4 days at the very dry air at the Bonneville Salt Flats.
Unfortunately, this data on the Manchu bow seems to taking inconsistent measurement to a whole new level. I’ll reach out to the author. Maybe I am missing something?
Alan
Post by: Shredd on May 20, 2021, 08:27:56 PM
Willi... I believe you to be correct... I thought about that right after I posted my comment... I am surprised Max or Roy did not catch that... :laughing:
Post by: Mad Max on May 20, 2021, 08:37:14 PM
Post by: Roy from Pa on May 20, 2021, 08:43:39 PM
Post by: williwaw on May 20, 2021, 09:23:20 PM
It might seem a small distinction to make, but when you start figuring efficiencies, using the total area would make a huge difference. anyways.... a slightly different question I hope you can shed some light on
Quote
So I don't think the limbs are storing more energy... I think it's how the limbs deliver the energy stored...
when considering the delivery of energy into the the arrow, it seems to me you have been suggesting one can "see" the difference between an efficient limb and an average limb by the shape of the curve, or possibly the shape of the area above the line? [ You are not allowed to view attachments ]
Post by: Shredd on May 20, 2021, 09:58:28 PM
We caught it, waiting on you to catch up dats all..
Suuuuure.......... :laughing:
Willi.... Curves are nice and fun to look at... But I like looking at the numbers... If you have 10% of your draw weight at 28" or higher in the beginning of your DFC that's good... 11% or higher that bow is smoking... And you want under 5% at the 28" mark... I don't concern myself with Dynamic efficiency, stored energy and kinetic energy... I look at the curve, read the numbers and run it through the chrony... I never made time to learn about the other stuff and I am not sure if it can help me build a bow faster... Those things seem after the fact...
I am undecided about the middle of the curve... I am not sure what numbers are best yet and how the limb can effect those numbers... So much more to learn....
Post by: williwaw on May 20, 2021, 10:58:15 PM
Quote
11% or higher that bow is smoking...
Ok, lets use that as an example. my bow pulls 50# at 28", and 11% of that is 5.5#, so if the bow is a smoker, I should see it pulling 5.5# in the first inch? the "in the beginning" part is unclear to me.
and the gain from 27" to 28" should be, 5% of 50, or 2.5# or under?
Post by: Shredd on May 20, 2021, 11:33:16 PM
Excuse me for my lack of ability to communicate my thoughts so they could be understood correctly...
Post by: williwaw on May 21, 2021, 12:01:11 AM
is your investigation of stacking in the interests of performance or smoothness or accuracy? I notice the target guys seem to go for longer bows than you typically find here.
Post by: Shredd on May 21, 2021, 12:11:06 AM
Post by: mmattockx on May 21, 2021, 09:56:09 AM
If you have 10% of your draw weight at 28" or higher in the beginning of your DFC that's good... 11% or higher that bow is smoking...
Ok, lets use that as an example. my bow pulls 50# at 28", and 11% of that is 5.5#, so if the bow is a smoker, I should see it pulling 5.5# in the first inch?
This is an interesting idea to have as a guide for early draw weight, thanks for sharing that one Shredd and thanks to williwaw for the clarification.
Mark
Post by: williwaw on May 21, 2021, 12:35:48 PM
If you are talking about my new thread, I wanted to simply find a guideline or rule of thumb... I want to know where the red line is and put some kind of number to it...
not sure if it's a red line, but a smoothness thing to some. and consider that stacking is raising daw weight without putting the extra energy into the limb or arrow, so if you were considering efficiency, it would be a concern.
One way to look at it is if stacking is not beginning to happen at the drawlength you are pulling, then maybe your limbs could have been shorter or bending different
Post by: Shredd on May 23, 2021, 11:55:43 AM
Post by: Buemaker on May 23, 2021, 02:30:19 PM
Post by: williwaw on May 23, 2021, 03:33:09 PM
Yah kinda lost me Willi... Maybe you can give me an example in numbers how bow efficiency is measured and how I can use that to make a faster bow... If it makes sense to me I could use that as a tool also...
Shredd,
If you are shooting lightweight arrows, flightshooting for instance, or building short bows that stack, then you might concern yourself with efficiency. Basically you would measure the arrow weight and speed and calculate the energy it has. This energy compared to a "perfect" dfc gives some idea of how efficient the limb is.
Post by: avcase on May 24, 2021, 04:12:46 PM
This is a good explanation of the importance of dynamic efficiency.
A bow with very high dynamic efficiency is able to safely shoot low ggp arrows because very little energy is left behind in the bow. So dynamic efficiency will probably influence where you decide to set the minimum arrow weight requirements for your bow warranty.
A bow shooting 3ggp arrows at 80% or better dynamic efficiency has a good chance of lasting many thousands of shots with no ill effect.
Alan
Post by: Mad Max on May 24, 2021, 05:34:31 PM
Question--There is a topic on Trad Gang forum about this bow, some of them are saying the DFC is very inaccurate and all over the place. Can you help them understand? Question from me The two 14# gains at 13/14", is that the point when the string lifts off the bridges ?. I love it myself. Thanks
Answer--Yes indeed, that's where the string leaves the bridges, giving it that distinct two-stage draw.
People say a lot online, haha. This graph has been questioned a lot but people with similar bows came to similar results. It's inherent to this design.
But I must admit the first time I pulled one I was also quite flabbergasted, once you get over the hump it feels like letoff.
It's not actually letoff of course, but as your body gets in a better position to pull it, it gives the perception of being lighter.
Post by: Shredd on May 25, 2021, 12:06:02 AM
Post by: Mad Max on May 25, 2021, 07:13:19 AM
This graph has been questioned a lot but people with similar bows came to similar results. It's inherent to this design.
Post by: Shredd on May 25, 2021, 08:17:31 AM
Post by: Shredd on May 25, 2021, 08:33:18 AM
Post by: Shredd on May 25, 2021, 08:50:40 AM
Wait until y'all see my latest discovery on the smoothness of draw of bow limbs... And yes, it takes some understanding of a DFC, which will be explained... And Yes... To see what is exactly going on, you need an accurate DFC... ;) :goldtooth:
Post by: Shredd on May 25, 2021, 09:36:04 AM
You have two nice high performance cars... The original car was painstakingly made by the manufacturer... The second car was a knock-off of the first and they cut a few corners but the car looks great and looks exactly like the first car and even has the same engine and transmission... However at high speeds the first car is faster and seems to ride more smoother and better on gas consumption... Now to you everything looks the exact same... Even the Lines and Curves look exactly the same...
Here is the riddle for you... Can you tell me what the difference is between these two cars?? Can anyone of you solve this riddle??
Post by: Mad Max on May 25, 2021, 11:54:59 AM
You can t compare to any thing except another horn bow.
Maybe I should have said Check out the poundage gains on this horn bow?
The original bows were built to cast a heavy arrow threw more than 1person.
The DFC was done in today’s world because, why not do one.
I have asked you if you read the article but you did not answer?
Post by: Roy from Pa on May 25, 2021, 12:03:19 PM
Post by: avcase on May 25, 2021, 03:55:13 PM
Looks like he misunderstood your question about the graph being accurate... I think he assumed you were saying people doubted the shape of the curve in the graph... Just to be clear... I am not doubting the general shape of the graph, it's just not totally accurate that's all... You can draw a circle freehand and you can draw a circle with a compass... Let's just say that graph was drawn freehand... Nothing wrong with that it's just not accurate and you really can't use the numbers to compare to another bow with a similar dfc... It would kinda be like running a drag car and having a guy at the end of the track counting and not using a stopwatch... 1 mississippi, 2 mississippi...
Very well stated!
I agree that the general shape of the force draw curve is believable, but the data doesn’t support the arrow speed or bow efficiency numbers that are reported with it.
Alan
Post by: Shredd on May 25, 2021, 04:59:16 PM
Mark... I read this article years ago and I think I have read it a second time since then... Now I just touched over it again...
First off... Don't bet your house on everything you read... Who is this expert any way... How does a bow jump from 2# down to 1.5# back to 2# and then up to 2.5# back down to 2# on the DFC... For the life of me I have never seen this before, actually I probably have... :laughing: Second... Shooting that heavy an arrow at that speed doesn't sound right... I am not gonna believe it or disbelieve it, it just does not sound right to me... Third... This rule about heavier bows not shooting a lighter arrow fast, I believe applies to most bows... I have heard your fastest fiberglass bows are around 50 to 60#... Anything heavier the limbs start getting too heavy to shoot a 10 gpp arrow fast and start slowing down... Fourth... I have a huge respect for these composite bows... I am amazed how they engineered these things back then... And last but not least... The DFC is fine... It looks pretty much like what a bow that style would produce... It's just not accurate, which is fine... 95% or more of DFC's out there are not accurate any way...
Ok... I am over this... If anyone can't solve this simple riddle that's Ok too... Alan... What about you?? Can you solve the riddle??
Post by: Shredd on May 25, 2021, 05:12:05 PM
Post by: avcase on May 25, 2021, 05:41:26 PM
He who completes the riddle will gain enlightenment to the DFC... I Guarantee... Or you money back... :goldtooth:
What is the riddle again? Is it the assumption that a heavy draw weight bow (for example 100#+) will not shoot a 10ggp @ 28” draw arrow as quick as a 50# bow?
The heavier bow will have the advantage with an identical ggp arrow most of the time. This is especially true for shooting lighter arrows. It depends on the mechanical properties of the materials used, bow design, and ratio of draw weight to draw length. An all-wood bow and unidirectional carbon backed bow may not show a big difference at lower versus higher draw weights. A glass bow will generally show higher efficiency at higher ratio of draw weight to draw length. This is why an Excalibur recurve crossbow with solid glass limbs can have a higher dynamic efficiency shooting 1ggp arrows than some 40-50# glass or carbon backed recurves shooting 10ggp arrows. The effect of the ratio of draw weight to draw length is even more pronounced with sinew-wood-horn composite bows.
Or is the riddle about the two cars, where the horsepower and torque curves are the same, but high speed performance and fuel mileage different? This indicates a difference in dynamic efficiency.
Alan
Post by: Shredd on May 25, 2021, 06:09:32 PM
I will read what you have to say about heavy weight bows later when I can contimplate on it...
Post by: Longcruise on May 25, 2021, 08:00:44 PM
So, my riddle for y'all is why would this be so...... if my opinion is correct. It’s a riddle in a riddle with a side of conundrum. :)
Post by: avcase on May 25, 2021, 08:42:23 PM
Alan
Post by: williwaw on May 25, 2021, 09:02:15 PM
A glass bow will generally show higher efficiency at higher ratio of draw weight to draw length. This is why an Excalibur recurve crossbow with solid glass limbs can have a higher dynamic efficiency shooting 1ggp arrows than some 40-50# glass or carbon backed recurves shooting 10ggp arrows. The effect of the ratio of draw weight to draw length is even more pronounced with sinew-wood-horn composite bows.
Alan
Does the advantage of the higher efficiency limb come from working at a higher stress?
Or perhaps such a limb, when working at a higher stress, can store the needed energy with less mass?
Post by: Shredd on May 25, 2021, 09:31:42 PM
And you are also saying that 100# bow is definitely faster than a 50# bow with 5gpp arrows with both bows being of the same design??
Post by: Longcruise on May 26, 2021, 12:10:09 AM
That's the answer to the riddle of why I hold that opinion.
Then there's hysteresis. Maybe that would explain why I'm wrong?
Post by: Shredd on May 26, 2021, 11:08:05 AM
If you noticed, I said, "I have 'Heard' your fastest fiberglass bows are around 50 to 60#"... I will never say something is a fact unless I know first hand through personal experience... Now I don't know who to believe... I do know for a fact that bows under 35 and 40# start losing performance of the same design... But I believe that the performance can be increased by changing the design... Lighter weight bows are a different animal...
It's tough dealing with this stuff sometimes... I have been mislead numerous times by a seasoned bowyer... Even me, myself could be wrong... I could have made a mistake somewhere down the line and misread the results that I was working on... And I believe some people have not even experimented and make chit up in their heads that they believe is true... So be aware people... Not everything you hear is true just because someone has made bows for a good bit of time...
I thank you guys for bringing this to light...
Post by: Roy from Pa on May 26, 2021, 11:13:09 AM
:wavey:
Post by: Shredd on May 26, 2021, 11:20:24 AM
Maybe a little too passionate and go over board...
Post by: Roy from Pa on May 26, 2021, 01:46:31 PM
Now don't go getten a wedge in yer undies, just messen wif ya...
:laughing: :wavey:
Post by: avcase on May 26, 2021, 06:55:15 PM
So, you are saying the statement is false... It is what I have heard and I believe most of the bows in the WTT contest were in the 50 to 55 lb. range... Why wouldn't someone make a 70 to 80lb. bow and blow the doors off the competition??
And you are also saying that 100# bow is definitely faster than a 50# bow with 5gpp arrows with both bows being of the same design??
Hello Rich,
I don’t know what the rules were for the “Walk the Talk”. My guess is that heavy bows would have represented a very small percentage of the market for the bow builders that participated.
There is no easy rule that will help estimate the impact on performance between a 50# and 100# version of a similar design. For typical glass backed designs, the trend should favor the heavier bow.
Alan
Post by: Shredd on May 27, 2021, 12:20:11 PM
Allen... I never thought about rules... They may have stated 60# max in the rules... I just heard numerous times that anything over 60# the limbs start getting heavy or possibly even start stacking too soon which could take away from performance... Which kinda sounded legit to me... None of this involves me anyway right now... I build bows 30 to 50#...
Post by: avcase on May 27, 2021, 03:05:24 PM
We find ways to become proficient at meeting whatever requirements we choose to focus on. For me, I am solely focused on building bows that provide maximum performance and durability only for flight archery. Everything else takes a back seat. So I do a majority of my testing shooting 5ggp or less arrows, and I tend to focus on heavier draw weights. These requirements drive my bow designs and build techniques and I eventually find ways to meet the challenge. But if I suddenly decided to shift my focus and build a 35 pound bow that was optimized for shooting heavy 15 ggp arrows at a long 32” draw length, then I would really struggle to come up with anything better than an average performing bow.
However, if we look at it purely from a technical design point of view, a heavier draw weight glass-composite design should outperform a lower draw weight design with identical ggp arrows and draw length.
Alan
Post by: williwaw on May 28, 2021, 04:43:12 PM
However, if we look at it purely from a technical design point of view, a heavier draw weight glass-composite design should outperform a lower draw weight design with identical ggp arrows and draw length.
Alan
also from further up,
Quote
A glass bow will generally show higher efficiency at higher ratio of draw weight to draw length.
Alan, would you explain why this is true?
thanks