[Lightgeoduck]

In a recent discussion in the "BGF Speed club" thread, NightKnight asked me to make a cone with the back end taped off to see if there is an effect in speed. I grasped the basic idea of the theory, (which I can't explain , but I understood it enough to do something a bit different, in the attempts to reach the goal of improved speed.

I made two darts for the test.
A standard dart for the control
A prototype to test.

I took a number of shots with both darts to get an average of each.

I won't give exact speeds, but I did manage to get a 20% average increase in speed with the prototype. Lowest was 5% and highest 25%.

I am still working on a better balance with the weight of the darts, and with all of the other variables to project concrete data for the test is quite difficult (for me at least). However, the test was worthy enough to see that the chane affected the speed in the positive. It seems to me at least.

Pics below are of the two darts used.

 

[treefork]

Seems feasible. Reminds me of the tapered off bike helmets used by word class cyclist. There were wind tunnel tested to finalize the design.

 

[NightKnight]

Impressive results and great outside of the box thinking! I love it!!!

 

[neondog]

What is the muzzle to chrony distance?

 

[Lightgeoduck]

Not too far. 3, 4 feet? I figured distance didn't matter, since I just want to see the percent change, and going for speed.


LGD

Oh, the cone was closer to the end of the skewer, but I fiddled with it too much

 

[superman365]

thats interesting.....I'll make my own to test

 

[Carbon]

Very cool. My only thought is that as far as aerodynamics go you might want to make the tapered part flush with the cone part. I don't know how much it would affect it, but over longer distances it could slow it down.

 

[Lightgeoduck]

Very cool. My only thought is that as far as aerodynamics go you might want to make the tapered part flush with the cone part. I don't know how much it would affect it, but over longer distances it could slow it down.

I will try that, but not for aerodynamics though. The design is only effecting the pushing air, the bigger cone is in the front, so the flight should be the same as the standard dart and doesn't affect how the dart cuts through the air.. I could be wrong though.

As far as distance, I am not sure, I am only trying to go for speed.

LGD

 

[Carbon]

My thought being that it could create turbulence..

 

[NightKnight]

My thought being that it could create turbulence..

It should reduce it, if anything. I will refer you to my thread on cone aerodynamics.

 

[Carbon]

Define "it" please

 

[NightKnight]

The "it" I refer to is turbulence.

 

[Carbon]

ah, I see. Well I was just thinking that with a ridge like that the air around it might "whirlpool" like on the wing of a plane where there is a seam for the hinge of an aileron.

 

[NightKnight]

See, thats the thing. A cone already has a low pressure wave behind it. LGDs secondary cone would fit squarely in that zone.

 

[Carbon]

oooohhhh, I get it. Very cool! That's actually a very cool picture you've got there.

 

[NaturalFork]

Makes sense it would be faster. I am just way to lazy to make cones that way. Good work duck.

 

[Pelletor]

That is some amazing and interesting photography AaronC.

I modified a dart cone to see if it made a difference and it did seem to improve things so I dug it out and shot it a couple more times a little while ago ( maybe 30 min) and it did seem to penetrate more and fly a bit flatter. But I gotta say looking at your images in post #14 I don't see why my shape made any difference? Was it all subjective, dunno?

I took a couple of pictures to show the details.

This wire dart is an older shorter one but the cone is milk jug plastic (HDPE) made during my transition time from the conduit BG (see traces of rust) to the PVC BG and even my newish Al BG. I "feathered" the rim of the cone to accommodate all my BG ID's. The pink stiff if cut from 1/2" thick pink insulation foam board held in place with Gorrilla Glue.

 

[NightKnight]

One factor may be reduced volume of air in the tube. This would matter more when the dart first starts moving. During the first 1" of travel in the tube the amount of air volume that is pressureized is significantly reduce with that cap on it. Thus, you get more power with your breath. Once it gets a few inches down the tube I suspect that the accelleration is the same. I also think that the range once it leaves the tube would be the same between them.

 

[superman365]

Thats an interesting dart you made there