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@@bowhunter7922 hey great question no I definitely did not assume constant velocity, I actually built a ballistics calculator based on a study of arrow drag from the Japanese institute of technology which found drag coefficients of an arrow. Fom that I determined the drag per interval from launch to x yardage to determine what would be the downrange velocity. However, some discussion in the video is discussing the two most common arguments of today. Which are energy based penetration estimate vs a momentum based estimate. Neither are accurate which ED Ashby confirmed in his testing as well. I then used the poncelet model of penetration specifically a solution for a non deforming elongated rod to estimate penetration which followed much more closely with EDs results and others. Thanks for your question and support, take care.

Thank you very much!

Thanks for the tip! I appreciate the support take care, Lucas

@@davidvedder2145 I’m working on a way to measure this. We will see if it works

@@C.Fowler the FOC video comes after this one. FOC Flight, Penetration and Buckling? Archery Eduction Video 4 all about FOC th-cam.com/video/uKjj2wqxoOU/w-d-xo.html

@@loganchapman105 thank you will do! I realized too late after I posted that I never did that. It’s kinda like watching paint dry isn’t it. 🤣. Take care, Luc

@@thewhiskybowman the wind is blowing from top to bottom, many people had the same question so thank you for asking. More videos to come thanks for the support. Take care, Lucas

@@Lucas_Palmer_bownerd_engineer Thanks for the reply, I did have a look at the questions before posting and hadn't noticed that it had already been asked. Unfortunately I don't think youtube always shows us (the viewers) all the comments, which must be frustrating for content providers having to answer the same things over and over.

@@thewhiskybowman Its all good! I don't mind the comments with questions, it helps me to know what I need to explain more next time. I made that comment such that you didn't feel bad for asking since many people thought the same thing. It's a good question to answer multiple times makes the answer easier to find. You are absolutely correct TH-cam does not show all or even in order the comments. Sometimes I miss comments as well and I am supposed to get a notification for each one! Anyway take care and thanks for you support! Luc

@@gowithabow your welcome stay tuned lots more to discuss!

Agree!

Not yet.

I’m trying to figure out a way to incorporate this as well. Thanks for the suggestion.

@@Mr.bowbender I have a short video addressing this question. The fan is pulling air across the vanes so airflow is from top to bottom same direction as an arrow actually experiences. Thanks for the question you and many others have had the same take care, Luc

@@Lucas_Palmer_bownerd_engineer ok that makes more sense. Keep up the good work. Can't wait to see more tests.

@@Mr.bowbender thanks for the support. I’ll keep them coming a little at a time!

Thank you! Take care, Luc

Yes absolutely rotation about the tip is different than how a true arrow behaves. Essentially this would be an arrow with 100%foc. However to compare fletchings it’s a fair comparison. I’m working on how to support the shaft from the cg while still allowing it to spin.

Pulling air.

You are correct this is exactly the setup I have as well the fan is pulling/sucking air across the arrow.

@@Lucas_Palmer_bownerd_engineer oh nice! Did you chamfer and de-burr the intake tube’s mouth? Probably would make for very minor discrepancies either way but just throwing ideas out mostly haha

@@tmalonso I did not I’ll give that a try I am also making a large intake cone as well. The flow has very minor turbulence.

@@Lucas_Palmer_bownerd_engineer best of luck with it, great experiment, excited to see more!

I’m working on it but probably a couple months learning kotlin and jetpack compose now. I hope sooner but just depends how long it takes for me to learn.

I’ll look into that thank you for the suggestion.

That is something I didn’t even consider thank you very much for the suggestion. I’ll have to re-evaluate this and try to determine this for future test! Thank you very much for the suggestion! Take care, Luc

@@Lucas_Palmer_bownerd_engineer I cant say for certain how much of a difference you will see but I think you can go back and look at the videos of all the trials you did and examine the first 1 second and see if there is any appreciable difference between vanes. simply take a measurement at the peak amplitude at various times and see which one has the strongest initial restoring force.

So interestingly enough it turns out shaft flex is the bigger cause of laminar vs turbulent. Because traditional bows create a large paradox of the shaft they experience a larger drag coefficient roughly 2.6 where a compound bow with a shoot through riser and a stiff enough shaft has much less shaft paradox. If the arrow is stiff enough, and therefore the drag coefficient is lower at about 1.5-1.6 and experiences laminer flow The Japanese sports institute has shown this to hold true for Reynolds number up to 2.4 x 10^4. Very fast bows north of 320fps depending on arrow geometry or larger shaft flex the flow changes to turbulent and the drag coefficient increases to roughly 2.6.

Interesting thought I’m trying to figure out the best way to measure spin rate. If I can figure out an accurate measurement I’ll see if I can test that theory. Thanks for the suggestion!

@@Lucas_Palmer_bownerd_engineer Always!

I tried a leaf blower the fluid flow pattern is extremely turbulent I have a larger fan now that will be much faster. The fan in the video is a 195cfm inline duct fan.

Absolutely! That is the plan eventually test every vane from angles ranging from straight to 6 degrees or so or whatever the maximum is.

Yes absolutely, however the wind in the wind tunnel is just under 17fps. The results can only be compared to each other rather than arrow in flight. So the test compares vanes to each other. Whichever performs best likely will perform the best on an arrow shaft.

Thank you for the suggestion! I’ll look into that.

More to come! Thanks for watching.

My thought as well since all of theses fletching are relatively the same size. That is making me think we maybe able to classify fletchings in terms of surface area facing the apparent wind. This would be great if we can determine the fletching size needed to stabilize a broadhead of a certain size with both arrow length and FOC to complete the equation. Maybe we will get there maybe not. Thanks for watching and the discussion. Luc

@@Lucas_Palmer_bownerd_engineer measure pressure in different angles with broadhead and vanes, wouldnt that create some value for the lift? lets say you measure it vertical on fixed broadhead from flat size and sharp size, then on 45 degree and straight ahead, do the same for vane, there it could be possible to calculate estimate for value of center of pressure, center of pressure needs to stay behind center of gravity for arrow to stabilize

@@flyfin108 yes we could approach it from that direction as well. However the only variable we don't know is rate of stabilization. You may also create a teeter totter effect with your arrow as you stabilize which we would not want. If CP is behind CG the arrow will be listed as stable all this means is that the tail will follow the tip, However the rate at which the arrow gets to stabilization if not launched perfectly (hand torques, poor tuning) or if the arrow is acted on by an external force is important. External forces can be drag, cross wind, a stick, etc. If you are familiar with damping think about the differences between underdamped, critically damped, and over damped. Ideally for an arrow we want rapid stabilization without oscillation. Thanks for the comment!

@@Lucas_Palmer_bownerd_engineer im trying to tune suspension of an 911 at assetto corsa currently, wish i knew more about damping but going with trial and error, front is insanely hard to get balanced over the bumps as its so light, if i remember right the "rocket guy" at ranch fairys podcast said that how much behind CP is of CG dosnt matter (much) as long as it stays there, so it could be just over all spine, im no rocket scientist for sure

@@Lucas_Palmer_bownerd_engineer been learning the bow tuning for almost an year now, i think its possible to make fixeds fly straight without vanes, fixeds thats not balanced

Haha just remember the wind tunnel speed is much slower than your actual arrow so stabilization would scale and be significantly faster in arrow flight. If it’s linear the speed is 15 times slower so if the stabilization time is 15 times quicker stabilization would be around 0.64 seconds…. If it is linear I don’t believe(don’t know for sure) it is but it’s just an example. Regardless the test is comparing each cane to one another independently of a lot of other variables. Thanks for watching.

Thank you!

The test is not inaccurate as long as we are careful about what we are saying results are. At best the test only shows that vane angle has much more to due with stabilization than vane shape but more testing is needed. The blazer is not worse than others the blazer being at a different angle performed different but we still have to test the other vanes at said angles as well to determine if they perform as expected which is longer to stabilize.

Watch the second half of the video. 1) The arrows can spin freely it was a requirement I set for the fixture. While there is slight friction between the tip of the arrow and the magnetic suspension it is minimal and equal to all arrows. 2) the fan is in suction pulling air across the fletchings. The air flow is from top to bottom not bottom to top. My apologies I should have made both of these points for clear. Yes vane angle purpose is for exactly what you said to increase relative surface area towards the wind. Thanks for watching and the support. Lucas

My theory is nearly the same as the others but I’ll have to test it to be sure. I have hundreds of more test coming but the video was already getting lengthy! Thanks for watching, Lucas