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Mar 20 17 12:44 AM

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Hey everyone !

Was wondering if anyone has used a low friction teflon coating in their battle to increase dart speed . I've been wanting to try a more permanent coating(not just liquid or powder) that seals into the metal or wood of the blowgun . Apparently Home Depot sells DuPont Brand teflon coating .A while back blowguns were sold commonly with teflon coating and they all claimed at least 10% higher velocity .Anyone here had experience with coating a barrel that way??

Also scientists have come out with a almost frictionless coating that is extremely better than teflon . A dart in theory would nearly float in the barrel !! It's called NFC coating and another one you can google is BAM coating . It can be applied to anything .They are still in the commercial market so for them just to polish and coat a blowgun would be hundreds of dollars ...but think of how fast your dart/arrows would be ..your friends will think you've been breath training with scuba divers and navy seals .... 
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#1 [url]

Mar 21 17 8:11 AM

Don't expect huge changes in speed with low friction coating. Arrows from bows and pellets from slingshots don't have to fight the friction of a tube and they aren't that fast.

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#2 [url]

Well you may be right it won't be huge but even the commercial blowguns with coating claim at least 10% increase in speed/distance; so even by all of our classic tournament rules, even a person shooing with low lung capacity 10 meter target would see that 10% no doubt . If he or she was a few feet shy of the bullseye on a flat 0 degree or nearly flat shot ;they now hit that target(bullseye) with 2-3 feet less drop. And for people like me who shoot long distance darts/arrows to max range (45 degree angle)like 400+ feet that measly 10% coating just gave me 10-15 yards of extra range . And as far a pellets and arrows go, they go who knows how many times farther and faster than blowgun darts .For blowguns esp. longer ones barrel friction/drag is huge .I also shoot 2-3 foot arrows that weigh on average 15-20 grams (225-300 grains) from a seven foot .63 caliber barrel . And ten 10% is huge when I'm trying to get the arrows to shoot a flat 10-15 yards . Right now they max outdistance a little over 100 yards where regular cone darts hit near 150 yards . A basic primitive bow can get arrows over 200 yards .  Pellets can be shot even farther . My goal is to set a world record at over 200 yards human breath only . Low drag fin and abdominal  style darts and arrows ...a chronograph my be in order to test actual barrel velocity (fps) with lubes and coatings vs regular barrel.

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#4 [url]

Hey Pime, Thanks !

i had older posts about the subject and a link for under "world record blowgun dart " on YouTube . This guys shot hit around 556 feet,But his pipe appeared to be chocked or tapered at the end and he had a unique mouth piece and/or magnets . And his darts I have no idea how he even got them to seal in the bore ...

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#5 [url]

Yes , hilltop
this video as been reported by Fukiyaman in this forum last year.
It seems to be actualy the max long distance word record  "officialized"  by a video
he used   a very low drag cone propellant of his invention.

about using low friction barrel system , i agree with Calina



 

Last Edited By: pime3 . Edited 1 time.

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#6 [url]

Do you have any idea how he seals those darts in the barrel  ? And if you look close you can see when his gun is on the tripod that it is clearly choked or tapered at the muzzle.. and in the video where he's shooting glass you can hear when he blows a very distinct noise like pressure holding the dart back until release ..and his mouth piece turns into some kind of air flow booster ... I'm sure all that together (darts, taper , and extra pressure ) gets him in the 500+ foot range . I wonder how far he shoots a regular cone dart from a straight pipe . 

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#7 [url]

 Il utilise un propulseur fait de papier plié en forme de croix.Le   souffle impulsif produit le gonflement ( déploiement)  quasi  instantanément du papier contre la paroi circulaire du tube , ce qui réduit fortement  les fuites d'air .Cela permet l'obtention de la force de propulsion dans le tube identique a celle d'un cone étanche.Les japonais sont maîtres dans l'art de plier le papier.Personnellement mes tentatives de produire des cones en papier pliés en forme de croix n'ont pas ete satisfaisantes. En sortie du tube , le papier reprend  instantannement la forme de pliage initiale aidee aussi  par l'action  du frottement de l'air sur le propulseur  en vol libre.La surface offerte en vol  libre par la forme en croix produit une resistance de traînée tres inferieure à celle  de.la forme conique . D'après mes essais et mesures sur ma soufflerie personnelle , le coefficient de traînée Cd mesurée sur la forme en croix  peut  être environ 3 fois plus faible que celle d'un cone du calibre du tube propulseur. ( soit un Cd de 0.1 à 0.15 pour la forme en croix).  

Traduction en anglais aidée by http://dictionnaire.reverso.net/francais-anglais/ 
He used a propeller   composed of folded paper  shaped as a cross.( Japonese people have a gift in folding paper )
Inside the tube , the blast effect rear the propeller instantaneously  produces the swelling of the folded paper against the wall of the tube and strongly reduces the air losses.Then the dart can move like a traditional cone inside the tube. 
When the dart reaches  the muzzle , the paper cone instantaneoulsy retains the initiale shape as a cross also helped by the external friction of the air .
 
The cross section of the propeller  produces a little drad force compared the circular section of a traditional  cone .
The trials and measures I performed using my own test bench schowed that the drag force of the cross shape is 3 times less than the cone shape of same calibre
.ie Cd coefficient of 0.1 to 0.15 for cross shape
​ ( 0.3 to 0.45 for cone shape ) 

​about noises of the video
the sound is confused , not clear for me 
I don't hear  like you , sorry

about " extra pressure system " you suppose to be used at the mouth peace
Video have a too poor  definition
I can't give an opinion on this existence of such a system on tbe video

but concerning the possibility to reach 556 feet , yes I can , IMO , it is possible
When I saw this video for the first time , I was amazed
My curiousity lead to perform some calculations

for a man in a very good health , it is possible without any overpressure system.
But several material parameters must be matched and optimized ,be experienced and to be methodical
first, study the external balistic to determine speed , inclinaison , matched with drag coefficient of dart you will use
second, study the internal balistic matched  with your breath , mass of dart , barrel long to verify that you will reach the necessary speed.
Dispose of a long field
ELSE,  the trials will be more  long and fastidius

And effectively a chronograph , can be usefull to test your breath and speed.
a peakflow can also be usefull , to verify your hability to have the necessary breath flow matched with the dart speed and the caliber of blowgun.
if not in available stock , the medical tables can be usefull ( give peak  flow , fonction of age , sexe, and heigth )
A good  peak pressure  must also be reached during the shoot to accelerate the dart into the barrel.( not a problem for people in a good helth )


PIME

Last Edited By: pime3 . Edited 10 times.

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#8 [url]

Yes Pime, you are absolutely correct! Well reaserched ! I now have to try a low drag dart such as the video or abdominal foam airfoil shape with fins, size and weight the same as a regular cone style and compare them in the field . Currently for my farthest shot ,(430 feet) I use 8 foot .56 barrel with around 3.5-4.0 gram nail dart with cone (2 inches long)
Also Pime ,I've read many of your older posts and you seem to be able to research very well the more scientific / mathematical aspects of blowguns , so I have a couple questions for you or our other readers to hopefully answer  . (Hope that's ok , thanks for your input!)
Question 1. In regards to the chronograph ,in your experience when compared side by side how much more feet per second or distance (max range )do the "alternative styles " of low drag darts have when compared to classic nail or wire cone dart? 5% more speed ? 10% ?????

Question 2. In regards to optimum breath flow , caliber etc , I can't get my 6 foot .63 to shoot a light cone style dart farther than the longer 8 foot .56 but I know I have enough air/breath power because I can use a 7 foot .63 better with heavier darts  but neither one beats the lighter dart /longer barrel . So according to your opinion would I get more distance/speed from a 10-12 foot true 1/2 inch pipe with maybe a 2.5 gram dart?? 
 

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#9 [url]

Answer to your question 1
Inside the barrel , drag coefficient as no effect on the final speed, because air colonn move at the same speed that the dart.
outside the barrel the drag force Fd slow down the dart depending , masse M , Cd coefficient, and instantaneous speed V, caliber
it is not possible to give a value for loss of speed because a lot of parameter are affecting.
Also it is necessary to go farther.. and perform a numerical application
Sorry  for formulas in forum ( it is for the good cause)

t = time
S=pi*cal^2*/4 area of caliber
ro= volumic mass of air ( 1.3 kg/m3 )
Fd= Cd*ro*V(t)^2*1÷2*S  ( conventionnal formula to determine the drag  force ) 
deceleration of dart , gamma =- Fd/M  
because v (t) is changing  during the fly , the exact final V  must be  obtained by integration 
But to simplify   , for short distances L  and if Fd is not too high ,  V will not change a lot , so we can appromimate as follow
fly time T will be T=  L/V
the final speed at impact will be  V(T) = Vo - ( Fd/M)*T with Vo the muzzle speed ( notice that loss of speed is proportional to fly time  T and deceleration factor Fd/M )
consequently , a heavy dart decelerate more slowly

and the response to question 1 , change of v in % is( Vo - V (T)  ) / Vo * 100
It is now easy to give an approximation  for loss of speed  for short distances 
numerical application
Vo = 50m/s
M = 2g = 0.002 kg
Cd = 0.4  ( paper cone )
L = 10 meter
Cal=14mm =0.014 m
Then

Fd = 0.1 Newton
- Fd/M = 0.1N / 0.002 kg = -50 m/s/s deceleration factor
T = L/Vo = 0.2 s  fly time
loss of speed at target ( 10m) = - Fd/M*T = -50m/s/s* 0.2s = - 10 m/s

final speed at target( 10 m ) = 50- 10= 40 m/s
loss of speed in % = 10/50 * 100 ie  20 %
( more accurate values are 40.9m/s , fly time T = 0.22s )

If M is only 1gramme , loss of speed would  be 40 % !
a drag Cd  of 0.2 would allow to keep the value 20 % loss of speed at 10m 

PIME

Answer for question 2 will be more expensive .
We are far from  subject "frictionless barrel coating " ....image









 

Last Edited By: pime3 . Edited 16 times.

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#10 [url]

Well that about settles it for the frictionless barrel coating . You and Calina are correct,coating helps but isn't going to change a lot . ,Thank you Pime for the formula ! You have just proven that aerodynamics and airflow research will get better results and faster darts than any coating/lubricant.,I also will move forward in pressure breathing with weights and aerodynamics . Anyone reading these discussions will see that this forum is the place to go to learn almost anything from the greatest minds of the blowgun sport today . Everything from great math formulas to ideas and designs are all here in the forum from around the world . As for me I'll be trying longer barrels (9-12 feet)and lower drag darts to try and pass 500 feet max range . When I do , I'll post a whole video . Thanks !

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