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                                Fuel testing

Spudgun.com has tested the following fuels listed on this page. The information includes the velocity of each fuel averaged over 3 shots. Velocity is the speed that a projectile is moving or feet per second (fps). The velocity was measured at the barrel of the spudgun. The projectile was a consist weight and shape, this was important to assure that each shot be consistent, and the only variable is the fuel used. Since metering of the fuel is difficult only 1 to 2 seconds of spray into the chamber was used, with the exception of propane. Since propane is a gas the problem of shorting out the ignitor was not a factor. Since moisture, temperature, humidity can effect the results, 3 shots of each fuel was used and an average velocity was calculated.

The distance that a projectile can travel can be calculated by the mass of the projectile and the velocity it is traveling. Other variables such as ballistic coefficient of the projectile, winds, angle of projectile fired will effect the distance. Since a  potato can vary in weight, density and shape, we did not use this for our tests. We substituted plastic wads for the projectiles. Using wads gave us a consistent variable since they provided a good gas-check seal on the inside barrel  and their weight was constant from shot to shot.

All measurements were recorded with a bullet chronograph and a test bed that consisted of a barrel rest for the spudgun barrel to assure that each shot was recorded at the same distance to the chronograph and ambient temperatures and humidity were constant.

Spudgun.com does not guarantee that you will achieve the same results that our test show. The data posted here is for reference only and spudgun.com is not responsible for any differences you may encounter.


Specifications:

Spudgun configuration:

Test #1, stock spudgun with 1.5" x 36" barrel.
Test #2, stock spudgun with 2" x 36" barrel.

Projectile:

Plastic wads.                     size             weight
                                            1.5             44 gr.
                                            2.0             80 gr.

Results, test #1:

36" X 1.5" BARREL

FUEL

SHOT 1

SHOT 2

SHOT 3

AVG FPS

Aquanet hairspray

427

398

383

402

Gumout

551

574

501

542

Secondwind deodorant

506

407

493

468

Gunk, Liquid fire

193

323

236

251

Cutter, Insect repellent

547

424

508

581

Static guard

563

606

574

581

Propane, (4 sec injection)

224

187

203

138

Propane (8 sec injection)

556

744

748

682

Old Spice      542      562      523      542

 

Results, test #2:

36" X 2" BARREL

FUEL

SHOT 1

SHOT 2

SHOT 3

AVG FPS

Aquanet hairspray

403

295

246

315

Gumout

455

331

235

340

Secondwind deodorant

520

448

328

432

Gunk, Liquid fire

123

356

429

302

Cutter, Insect repellent

718

623

722

688

Static guard

966

963

737

889

Propane, (4 sec injection)

168

165

185

173

Propane (8 sec injection)

693

634

580

636

Old Spice      663      686      656      668

Equipment:

Chronograph, Shooting CHRONY, model F-1

chorny.jpg (17764 bytes)     testbd.jpg (12359 bytes)

Summary:

During the tests, it was obvious that the fuel that had the finest spray worked the best. The Cutter, Static and Deodorant nozzles gave off a very fine mist. This fine mist gave excellent air/fuel mixture and therefore gave the highest velocity. Other fuels tested had a coarser spray, attempts to move the spray in a small circle to help distribute the fuel evenly in the chamber didn't really help much. Propane was tested with 2 different lengths of spray, anything over 8 seconds was a waste of propane and did not increase the velocity. Since propane was the only gas type fuel tested we could use a longer injection of fuel without the worry of wetting the ignitor tips and not getting a spark.

Since the projectile wads were very light (44/80, gr.), the velocities are higher than you would get with a potato. The readings were intended to show which fuels are better than others.  Even though the velocities will be reduced with heavier projectiles, you will still get a better shot by using the fuels that developed higher feet per second (fps)

I don't pretend to say that these are the only fuels to use and that they are the best. I know I'll get several emails telling me that I didn't test  this one or that one, or your fuel will kick these fuels ass. My intent was to give you some easy obtainable off the shelf products. Happy spudding...

As always, your comments are welcome....Larryb @ itis.com


copyright, spudgun.com, 1997-2014

Last updated 02/14/14

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