A puff of breath and 150 fps

[boyntonstu]

Here is an independent test done by Billy McCaskill from Baker LA.:


To stay with the current convention in referring to various blowguns, they will be listed such as 3836 (.38 caliber, 36"). All testing was done with the muzzle of the blowguns within 4" of the first sensor on the chronograph. Prior to obtaining any usable velocity data, approximately 30 shots were fired just to 'warm up' and to verify the consistency of the chronograph readings and lighting.

All darts used were commercially available target darts with molded plastic cones and 4" wires. 20 shots were fired for each caliber/barrel length, and velocities listed are rounded to the nearest .1 foot/second. Standard deviations were calculated but won't be included. All SD's were between 2.58 and 4.49, indicating fairly consistent velocity results within each individual velocity test. Tube volumes are also listed for all the combinations I tested.



Test 1 3836 Avg. Velocity 110.1 fps tube volume 4.08 cubic inches
Test 2 3872 Avg. Velocity 135.3 fps tube volume 8.16 cubic inches

Test 3 4036 Avg. Velocity 115.4 fps tube volume 4.52 cubic inches
Test 4 4048 Avg. Velocity 123.4 fps tube volume 6.03 cubic inches
Test 5 4060 Avg. Velocity 134.0 fps tube volume 7.54 cubic inches
Test 6 4072 Avg. Velocity 138.0 fps tube volume 9.08 cubic inches

Test 7 5036 Avg. Velocity 123.3 fps tube volume 7.06 cubic inches
Test 8 5048 Avg. Velocity 132.5 fps tube volume 9.41 cubic inches
Test 9 5060 Avg. Velocity 143.1 fps tube volume 11.76 cuic inches
Test 10 5072 Avg. Velocity 150.5 fps tube volume 14.11 cubic inches


This is interesting for several reasons;

A little pre-chamber with 100 psi pressure in the main chamber yields pretty uniform speeds around 225 fps and not much lower than the full chamber. GGDT will not predict this.

Curious.

[jackssmirkingrevenge]

Are these shots "human powered"?

IIRC the lungs can only generate around 3 psi

[jeepkahn]

Are these shots "human powered"?

IIRC the lungs can only generate around 3 psi

I'm sure they are lung powered, those readings are pretty consistent for a blowgun with 1gm darts... even plugging some #'s in ggdt give results consistent with these... 3psi and a small chamber pushing .40 darts through a 36" barrel shows 125+fps

[mark.f]

A little pre-chamber with 100 psi pressure in the main chamber yields pretty uniform speeds around 225 fps and not much lower than the full chamber. GGDT will not predict this.

[maverik94]

hah, With my .50 cal., 7' long blowgun, shooting wooden dowel darts, I have gotten 187 fps.

[sgort87]

[Thread Title] A puff of breath and 150 fps

I think he used some kind of organic pressure chamber/compression source combination. I have a dual-chamber one that my mom and dad made back in the day, but I don't use it for shooting things very much these days.

[psycix]

organic pressure chamber/compression source

And that's not just his mouth...

[jackssmirkingrevenge]

And that's not just his mouth...

You mean the valve seat