Test 1: 2 Bates grains in 38/240 case fired
on see-saw test stand - fast burn
Test 2: 3 Bates grains in 38/360 case fired
on stable test stand - moderate burn
Test 3: 3 Bates grains in 38/360 case fired
on stable test stand - moderate burn
Test 4: 3 Bates grains in 38/360 case fired
on preliminary analog test stand - fast burn
Test 5: 3 Bates grains in 38/360 case fired
on stable test stand - moderate burn, no video
Test 6: 3 Bates grains in 38/360 case fired
on analog test stand A - moderate burn, regressive curve, 188 N-secs
Test 7: 1 long inhibited grain in 38/360
case fired on analog test stand A - Progressive burn, as expected, 178
N-secs
Test 8: 3 Bates grains in 38/360 case fired
on test stand A - strong spike at start, then regressive burn, 198 N-secs
Test 9: 3 Bates grains in 38/360 case, first
use of analog test stand B - regressive burn, not expected, 196 N-secs
Test 10: 3 Bates grains in 38/360 case
fired on analog test stand B - progressive/regressive burn, 129 N-secs*
Test 11: Single uninhibited grain in 38/360
case, test stand B - Strong, short burn, no CATO, no video
Test 12: Single uninhibited grain in 38/360
case, test stand B - Strong, short burn, no CATO, 133 N-secs*
Test 13: 3 uninhibited grains in 38-360
case, test stand B - Strong, short burn, no CATO, Max psi @ 1750, 161 N-secs
Test 14: 3 Bates grains in 38/360 case,
test stand B - Good burn, 156 N-secs
Test 15: 3 Bates grains 1 week old, with
Fe2O3 in 38.360 case, test stand B, fourth ignitor with Mg works, 138 N-secs
Test 16: 3 Bates grains, recently molded,
with Fe2O3 in 38.360 case, test stand B, good burn, 147 N-secs
Test 17: 3 Bates grains, very slow propellant,
test stand B, good burn, 158 N-secs
Test 18: 3 Bates grains, poster-board used
as case liner, test stand B, good burn, 137 N-secs
Test 19: 3 Bates grains, very slow propellant,
test stand B, good burn, 147 N-secs
Test 20: 3 Bates grains, very dark, very
slow propellant, test stand B, long burn, 137 N-secs
Test 21: 3 Bates grains, 9-second rcandy,
test stand B, long burn, 162 N-secs
Test 22: 4 Bates grains in 38/480 casing,
test stand B, Short, strong thrust, No CATO, 230 N-secs
Test 23: 6 Bates grains in 38/720 casing,
test stand B, very strong thrust, No CATO, 383 N-secs
Test 24: 3 Bates grains in 38/360 casing
with Aerotech delay, static test in Cedarville, NJ
Test 25: Flight test in Ariel, 4 Bates
grains in 38/480 casing, Aerotech delay charge. Worked fine, recovery
OK.
Test 26: 2 Bates grains in 38/240 testing
duct tape as inhibitor. Worked, but tape blew out nozzle at end.
95 N-secs
Test 27: 2 Bates grains in 38/240 testing
aluminum foil tape as inhibitor. Worked well. 99.9 N-secs
Test 28: 2 Bates grains in 38/240 case,
3 dips in paraffin. Ignition delayed but OK. 81.7 N-secs
Test 29: 1 Bates grain in 38/240 case,
wood plug to fill tube, Al foil inhibitor, 1 dip paraffin, 89 N-secs
Test 30: 1 Bates grain in 38/240 case,
wood plug to fill tube, Al foil inhibitor, 2 dips paraffin, new ignitor,
48 N-secs
Test 2
9/1/02A
38/360 case with 3 Bates grains, better inhibitor
Click here for a video of this test (828k
file, .mpg format, 5 seconds of video)
Static test: 3 Bates grains in Dr. Rocket 38/360 case
Inhibited with 2 layers manila-folder paper, secured with 5-minute
epoxy
Total propellant weight: 155g, burn rate: fast
Nozzle throat: 5/16 inch
Initial Kn: 169
Kn Max: 198
Final Kn: 164
Fired on stable stand.
Ignition: 0.84 second delay, followed by 1.04 second burn.
Impressions: Moderate, steady burn. Upon examination of
case, the inhibitor tubes were intact with tapered burns towards the ends,
suggesting good inhibition.
Test 3
9/2/02C
Replication of test 2
Click here for a video of this test (818k
file, .mpg format, 5 seconds of video)
Static test: 3 Bates grains, 38/360 case
Inhibited with 2 layers manila-folder paper, secured with 5-minute
epoxy
Total propellant weight: 154g, burn rate: fast
Nozzle throat: 0.325 inch
Initial Kn: 155
Kn Max: 180
Final Kn: 147
Fired on stable stand.
Ignition: 0.44 second delay, followed by 1.08 second burn.
Impressions: Moderate, steady burn. Just like in Test II
| Designation: | 9/8/02C |
| Propellant: | 9/2/02A recrystallized KN/SU, 24 seconds/inch at 1atm, primed with red/blue KN/SU at head |
| Grain Type: | 3 Bates grains |
| Grain Length: | 1.84 inches (each grain, average) |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 166.7g with inhibitor, 155g propellant alone |
| Inhibitor: | 2 layers manila-folder paper glued on with epoxy |
| Nozzle: | Used, Phenolic, throat = 0.338 inch dia. |
| Kn Ratios | Initial: 141 Maximum: 161 Final: 128 |
| Ignitor: | Electric match with 1/2g black powder held with masking tape |
| Mounted on: | Analog test stand A |
| Recorded: | Sony Mavica CD-1000, .mpg file |
| Ignition delay: | 0.08 second |
| Burn time: | 1.08 seconds |
| Peak thrust: | 55 pounds |
| Average thrust: | 39 lbs |
| Thrust: | 42 pound-seconds = 188 N-secs |
| ISP | 129 seconds |
| Thrust curve: | Slightly regressive, thought due to off-center core |
| Designation: | 9/9/02A |
| Propellant: | 9/8/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | Single outside-inhibited grain |
| Grain Length: | 5.75 inches |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 170g with inhibitor, 158g propellant alone |
| Inhibitor: | 2 layers manila-folder paper glued on with epoxy |
| Nozzle: | New, Phenolic, 5/16 inch throat = 0.3125 |
| Kn Ratios | Initial: 115 Final: 241 |
| Ignitor: | Electric match with 1/2g black powder held with masking tape |
| Mounted on: | Analog test stand A |
| Recorded: | Sony Mavica CD-1000, .mpg file |
| Ignition delay: | 0.24 second |
| Burn time: | 1.04 seconds |
| Peak thrust: | 65 pounds |
| Average thrust: | 38 lbs |
| Thrust: | 40.0 pound-seconds = 178 N-secs |
| ISP | 115 seconds |
| Thrust curve: | Progressive, as expected. |
| Designation: | 9/13/02A |
| Propellant: | 9/8/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | 3 Bates grains |
| Grain Length: | 1.87 inches (each grain, average) |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 159.3g with inhibitor, 148g propellant alone |
| Inhibitor: | 1 layer "Asbestos Free High Temperature Gasket Material" 1/32 inch thickness, epoxied on |
| Nozzle: | Used, Phenolic, throat = 0.36 inch dia. |
| Kn Ratios | Initial: 125 Maximum: 144 Final: 116 (expected, not realized!) |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand A |
| Recorded: | Sony Mavica CD-1000, .mpg file |
| Ignition delay: | 1.28 second |
| Burn time: | 1.00 seconds |
| Peak thrust: | 140 pounds (estimated, bottomed-out test stand A) |
| Average thrust: | 42.9 lbs |
| Thrust: | 44.6 pound-seconds = 198 N-secs |
| Thrust curve: | Initial spike and regressive, which were not expected |
| ISP | 137 seconds |
| Impressions: | Inhibitor failure seems likely cause of unexpectd thrust curve. Dip after peak is probably spring-rebound of the analog test stand. This provides an unintentional test of the strength of the Dr. Rocket casing, indicating that there is a substantial safety margin for this load. |
| Designation: | 9/15/02A |
| Propellant: | 9/7/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | 3 Bates grains |
| Grain Length: | 1.84 inches (each grain, average) |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 166.4g with inhibitor, 155g propellant alone |
| Inhibitor: | 2 layers manila-folder paper, epoxied on |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. |
| Kn Ratios | Initial: 165 Maximum: 189 Final: 150 |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Ignition delay: | 0.439 second |
| Burn time: | 0.96 seconds |
| Peak thrust: | 73 pounds |
| Average thrust: | 45.8 lbs |
| Thrust: | 44 pound-seconds = 196 N-secs |
| ISP | 129 seconds |
| Thrust curve: | Regressive, not as expected |
| Impressions: | 3 ignitors failed to fire this motor! Finally fired with 4th
containing 1g black powder & some Fe2O3.
Grains had been stored for several days, thus moisture acquisition seems likely to blame |
| Designation: | 9/16/02A |
| Propellant: | 9/8/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | 3 Bates grains |
| Grain Length: | 1.86 inches (each grain, average) |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 159.4g with inhibitor, 148g propellant alone |
| Inhibitor: | 2 layers manila-folder paper, epoxied on |
| Nozzle: | Once used, Phenolic, throat = 0.32 inch dia. |
| Kn Ratios | Initial: 165 Maximum: 189 Final: 150 |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Ignition delay: | 1.65 second |
| Burn time: | 1.08 seconds |
| Peak thrust: | 50 pounds* *Probably not. recalibrated test stand on 9/30/02 |
| Average thrust: | 26.8 lbs |
| Thrust: | 29 pound-seconds = 129 N-secs |
| ISP (Seconds) | 88.7 |
| Thrust curve: | Progressive/regressive |
| Impressions: | Moderate, steady thrust. Thrust measurements are of doubtful accuracy. |
| Designation: | 9/16/02B |
| Propellant: | 9/8/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | single uninhibited grain |
| Grain Length: | 5.51 inches |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 148.2g propellant alone |
| Inhibitor: | none |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. (after firing measures 0.32 inch dia throat) |
| Kn Ratios | Initial: 382 Final: 330 |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Recorded: | due to operator error, this test was not recorded. |
| Ignition delay: | (unknown) |
| Burn time: | (unknown) |
| Peak thrust: | (unknown) |
| Average thrust: | (unknown) |
| Thrust: | (unknown) |
| Thrust curve: | (unknown) |
| Impressions: | Strong burn, no CATO despite high Kn |
| Designation: | 9/16/02C |
| Propellant: | 9/7/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | single uninhibited grain |
| Grain Length: | 5.5 inches, chiseled at end, removing a 3-5 gram sliver of propellant. |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 139.5g propellant alone |
| Inhibitor: | none |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. (after firing measures 0.315 inch dia throat) |
| Kn Ratios | Initial: 380 Final: 330 (slightly less due to chip at end) Max PSI = 1600 (!) |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Recorded: | Sony Mavica CD-1000 |
| Ignition delay: | 2.4 seconds |
| Burn time: | 0.44 seconds |
| Peak thrust: | 154 lbs* *(maybe not, calibration of test stand B is questionable) |
| Average thrust: | 88 lbs* |
| Thrust: | 38.9 lb-secs = 171 N-secs * |
| Thrust curve: | somewhat regressive, as expected |
| Impressions: | Strong burn, no CATO despite high Kn |
| Designation: | 9/17/02A |
| Purpose: | To determine if complete inhibitor failure will cause case failure |
| Propellant: | 9/7/02A recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | 3 uninhibited grains |
| Grain Length: | 1.871 inches each, average |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 145g propellant alone |
| Inhibitor: | none |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. (after firing measures 0.32 inch dia throat) |
| Kn Ratios | Initial: 442 Final: 287 Max PSI = 1750 (!) |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Recorded: | Sony Mavica CD-1000 |
| Ignition delay: | 0.2 seconds |
| Burn time: | 0.439 seconds |
| Peak thrust: | 176 lbs* *(maybe not, calibration of test stand B is questionable) |
| Average thrust: | 103.6 lbs* |
| Thrust: | 45.5 lb-secs = 202 N-secs * |
| Thrust curve: | somewhat regressive, as expected |
| ISP | 114 seconds |
| Impressions: | Strong burn, no CATO despite high Kn. |
| Designation: | 9/27/02A |
| Purpose: | Replication of standard load |
| Propellant: | 9/7/02B1 recrystallized KN/SU, 24 seconds/inch at 1atm |
| Grain Type: | 3 inhibited grains |
| Grain Length: | 1.884 inches each, average |
| Grain outside dia: | 1.15 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 159g propellant alone |
| Inhibitor: | 2 layers manila folder paper, secured with epoxy |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. |
| Kn Ratios | Initial: 159 Max: 186 Final: 157 Max PSI = 600 |
| Ignitor: | Electric match with 1/4g black powder held with masking tape |
| Mounted on: | Analog test stand B |
| Ignition delay: | 1.12 seconds |
| Burn time: | 1.04 seconds |
| Peak thrust: | 70 lbs. |
| Average thrust: | 34 lbs. |
| Thrust: | 35 lb-sec = 156 N-sec |
| Thrust curve: | Rugged peak, progressive/regressive, as expected |
| ISP | 100 seconds |
| Impressions: | Longish ignition followed by strong burn. |
| Designation: | 9/29/02B |
| Purpose: | To determine if catalyst speeds burn at pressure |
| Propellant: | 9/29/02A2 recrystallized KN/SU, darkish, but with 0.5 percent Fe2O3, burns at 8.7 seconds/ inch at 1atm. |
| Grain Type: | 3 inhibited grains, had been molded a week before, somewhat sticky. |
| Grain Length: | 1.893 inches each, average |
| Grain outside dia: | 1.15 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 154g propellant alone |
| Inhibitor: | 2 layers manila folder paper, secured with epoxy |
| Nozzle: | New, Phenolic, throat = 0.3125 inch dia. After firing: 0.318 inch |
| Kn Ratios | Initial: 167 Max: 194 Final: 157 Max PSI = 625 |
| Ignitor: | Electric match with 1/4g black powder, then 1/4 g KNO3 with Mg turnings, held with masking tape |
| Mounted on: | Analog test stand B |
| Ignition delay: | 1.639 seconds (3 BP ignitors failed, 4th one with BP + KNO3/Mg turnings worked. |
| Burn time: | 0.84 seconds |
| Peak thrust: | 95 lbs |
| Average thrust: | 37 lbs |
| Thrust: | 31 lb-secs = 138 N-secs |
| Thrust curve: | rugged peak, slow rise and decline |
| Impressions: | Longish, ragged ignition followed by strong burn. Low thrust & ISP may be due to slow rise to brief peak and equally-slow decline, thus much of the burn at low pressure. Test stand B is still of questionable accuracy. |
| Designation: | 9/30/02B |
| Purpose: | Replication of 9/29/02B, but with recently molded grains. |
| Propellant: | 9/29/02A2 recrystallized KN/SU, darkish, but with 0.5 percent Fe2O3, burns at 8.7 seconds/inch at 1 atm. |
| Grain Type: | 3 inhibited grains, each individually molded and inhibited. |
| Grain Length: | 1.932 inches each, average |
| Grain outside dia: | 1.15 inches |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | 159g propellant alone |
| Inhibitor: | 2 layers red/green poster board, secured with epoxy |
| Nozzle: | New, Phenolic, throat = 0.333 inch dia. After firing: |
| Kn Ratios | Initial: 149 Max: 174 Final: 144 Max PSI = 550 |
| Ignitor: | Electric match with 1/4g black powder, held with masking tape |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.88 seconds |
| Burn time: | 0.96 seconds |
| Peak thrust: | 55 lbs |
| Average thrust: | 37.5 lbs |
| Thrust: | 33 lb-secs = 147 N-secs * |
| Thrust curve: | rough lump, slightly progressive |
| ISP | 94 seconds |
| Impressions: | Strong burn, no CATO. Test stand B is now overly pessimistic. Ignition easier with new grains. |
| Designation: | 9/30/02C |
| Purpose: | Replication of 9/29/02B, but with very slow-burning propellant |
| Propellant: | 9/30/02A1 recrystallized KN/SU, slow, incontinuous burn at 1atm. |
| Grain Type: | 3 inhibited grains |
| Grain Length: | 1.924 inches each, average |
| Grain outside dia: | 1.15 inches (estimated) |
| Core diameter: | 3/8 inch = 0.375 |
| Grain weight: | Grains themselves: 163.4g. (minus 8% inhibitor weight = 150g propellant) |
| Inhibitor: | 2 layers red/green poster board, secured with epoxy |
| Nozzle: | New, Phenolic, throat = 0.32 inch dia. |
| Kn Ratios | Initial: 154 Max: 181 Final: 155 Max PSI = 550 |
| Ignitor: | Electric match with 1/4g black powder, held with masking tape |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.36 second |
| Burn time: | 0.96 second |
| Peak thrust: | 50 lbs |
| Average thrust: | 37.0 lbs |
| Thrust: | 35.5 lb-secs = 158 N-secs |
| Thrust curve: | slightly progressive, but otherwise resembles ideal Bates-grain curve |
| ISP | 106 Seconds |
| Impressions: | Strong burn, no CATO. Test stand B is overly pessimistic. |
| Designation: | 10/10/02A |
| Purpose: | Replication of standard configuration but using poster-board for inhibitor and case liner |
| Propellant: | Recrystallized KN/SU (batch not recorded) |
| Grain Type: | 3 inhibited grains, |
| Grain Length: | 1.819 inches each, average |
| Grain outside dia: | 1.15 inches (estimated) |
| Core diameter: | 3/8 inch = 0.375 (may be a bit larger) |
| Grain weight: | Grains themselves: 163.4g. (minus 8% inhibitor weight = 150g propellant) |
| Inhibitor: | 2 layers white poster board, secured with epoxy |
| Nozzle: | New, Phenolic, throat = 0.295 inch dia. after firing = 0.305 inch |
| Kn Ratios | Initial: 154 Max: 181 Final: 155 Max PSI = 550 |
| Ignitor: | Electric match with 1/2g black powder, held with masking tape |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.241 seconds |
| Burn time: | 0.839 seconds |
| Peak thrust: | 52 lbs |
| Average thrust: | 36.75.0 lbs |
| Thrust: | 30.8 lb-secs = 137 N-secs |
| Thrust curve: | somewhat regressive, possibly due to off-center core |
| Impressions: | Good burn, no CATO. |
| Designation: | 10/12/02B |
| Purpose: | Replication of standard configuration but using poster-board for inhibitor and case liner |
| Propellant: | 9/2/02B recrystallized KN/SU, slow burning, not continuous at 1atm |
| Grain Type: | 3 inhibited grains, |
| Grain Length: | 1.795 inches each, average (grains are a bit too short, creating some difficulty in getting nozzle & washer to seat) |
| Grain outside dia: | 1.15 inches (estimated) |
| Core diameter: | 3/8 inch = 0.375 (may be a bit larger) |
| Grain weight: | Grains themselves: 155g. (minus 7% inhibitor weight = 142g propellant) |
| Inhibitor: | 2 layers white poster board, secured with epoxy (white board a bit lighter than red/green) |
| Nozzle: | New, Phenolic, throat = 0.298 inch dia. After firing: 0.307 |
| Kn Ratios | Initial: 171 Max: 195 Final: 159 Max PSI = 625 |
| Case liner: | 12 inches (3 turns) white poster-board, cut 5.75 inches long. |
| Ignitor: | Electric match with 1/2g black powder, pinch of Mg flakes, held with masking tape |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 1.08 seconds |
| Burn time: | 1.119 seconds |
| Peak thrust: | 47 lbs* *(maybe not, calibration of test stand B is still questionable,) |
| Average thrust: | 29.5 lbs* |
| Thrust: | 33 lb-secs = 147 N-secs * |
| Thrust curve: | somewhat regressive, possibly due to off-center core. |
| ISP | 104 seconds |
| Impressions: | Good burn. Case liner did not burn through at any point. 1/2 gram BP seems a bit much for an ignitor in these motors, will cut back on BP and continue to use Mg flakes |
Click here for a video of this test (820k
file, 5 seconds of video)
Click here for an Excel spreadsheet analysis
with thrust curve.
| Designation: | 10/13/02C |
| Purpose: | Replication of standard configuration but using white poster-board for inhibitor and case liner |
| Propellant: | 10/12/02A recrystallized KN/SU, very slow burning, chocolate color, made with Swedish "Ljus Sirap" |
| Grain Type: | 3 inhibited grains, |
| Grain Length: | 1.795 inches each, average (a bit too short. some difficulty in getting nozzle & washer to seat) |
| Grain outside dia: | 1.15 inches (estimated) |
| Core diameter: | 3/8 inch = 0.375 (may be a bit larger) |
| Grain weight: | Grains themselves: 155g. (minus 7% inhibitor weight = 142g propellant) |
| Inhibitor: | 2 layers white poster board, secured with epoxy (white board a bit lighter than red/green) |
| Nozzle: | New, Phenolic, throat = 0.3 inch dia. After firing: 0.307 |
| Kn Ratios | Initial: 171 Max: 195 Final: 159 Max PSI = 625 (probably lower due to slow burn rate) |
| Case liner: | 12 inches (3 turns) white poster-board, cut 5.75 inches long. |
| Ignitor: | Electric match with 1/2g black powder, pinch of Mg flakes, held with masking tape |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.440 seconds |
| Burn time: | 1.320 seconds |
| Peak thrust: | 32 lbs |
| Average thrust: | 21.55 lbs |
| Thrust: | 30.8 lb-secs = 137 N-secs |
| Thrust curve: | Most graceful so far, nearly symmetrical |
| ISP | 91 seconds |
| Impressions: | Good burn, but low thrust, indicates ISP advantage of higher pressures. |
| Designation: | 10/13/02D |
| Purpose: | Replication of standard configuration, still using poster-board for inhibitor and case liner |
| Propellant: | Recrystallized KN/SU, odds and ends from several batches kneaded together, burns 9 seconds/ inch at 1 atm. |
| Grain Type: | 3 inhibited grains |
| Grain Length: | 1.86 inches each, average - just about right |
| Grain outside dia: | 1.2 inches (a little larger than before: used 18 inch strip of poster-board as mold liner instead of 24 inches) |
| Core diameter: | 3/8 inch dowel = 0.375 (may be a bit larger, some measured at 0.43 inches) |
| Grain weight: | Grains themselves: 167.8g. (minus 7% inhibitor weight = 156g propellant) |
| Inhibitor: | 2 layers white poster board, secured with epoxy |
| Nozzle: | Phenolic, used once in test 10/13/02C, throat = 0.307 inch dia. After firing: 0.325 |
| Kn Ratios | Initial: 171 Max: 195 Final: 159 Max PSI = 625 |
| Case liner: | 12 inches (3 turns) white poster-board, cut 5.75 inches long. |
| Ignitor: | Electric match with 1/2g black powder & pinch of Mg flakes in masking tape. Nozzle sealed with foam ear-plug |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.440 seconds |
| Burn time: | 1.28 seconds |
| Peak thrust: | 42 lbs |
| Average thrust: | 28.4 lbs |
| Thrust: | 36.3 lb-secs = 161.5 N-secs |
| Thrust curve: | Nice flatish curve |
| ISP: | 106 seconds |
| Impressions: | Good burn. Case liner burned through only at pinpoints. |
| Designation: | 10/15/02A |
| Purpose: | Replication of standard configuration but using poster-board for inhibitor and case liner |
| Propellant: | Recrystallized KN/SU, |
| Grain Type: | 4 inhibited grains, |
| Grain Length: | 1.86 inches each, average - just about right |
| Grain outside dia: | 1.2 inches |
| Core diameter: | 3/8 inch dowel = 0.388 (average of several measurements) |
| Grain weight: | Grains themselves: 214g. (minus 7% inhibitor weight = 199g propellant) |
| Inhibitor: | 2 layers green poster board, secured with epoxy |
| Nozzle: | Phenolic, new, throat = 0.295 inch dia. After firing: 0.318 |
| Kn Ratios | Initial: 251 Max: 287 Final: 246 Max PSI = 1175 |
| Case liner: | 12 inches (almost 3 turns) green poster-board, cut 7-5/8 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking tape. Nozzle sealed with foam ear-plug |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.601 seconds |
| Burn time: | 0.84 seconds |
| Peak thrust: | 98 lbs |
| Average thrust: | 61.6 lbs |
| Thrust: | 51.76 lb-secs = 230.2 N-secs |
| Thrust curve: | Somewhat regressive curve |
| ISP: | 118 seconds |
| Impressions: | Faster burn than anticipated. Case liner burned through only at pinpoints. Inhibitor sleeves intact and firm. Shorter burn may be due to higher pressures. |
| Designation: | 10/24/02B |
| Purpose: | First test of 6-grain configuration |
| Propellant: | Recrystallized KN/SU, |
| Grain Type: | 6 inhibited grains, |
| Grain Length: | 1.84 inches each, average |
| Grain outside dia: | 1.2 inches (propellant only) |
| Core diameter: | 3/8 inch dowel for top 3 grains, average 0.404 inches
1/2 inch dowel for lower 3, average 0.538 inches |
| Grain weight: | Grains themselves: 318g. (minus 7% inhibitor weight = 296g propellant) |
| Inhibitor: | 2 layers poster board, secured with epoxy |
| Nozzle: | Phenolic, new, throat = 0.378 inch dia. |
| Kn Ratios | Initial: 247 Max: 270 Final: 224 Max PSI = 1100 |
| Case liner: | 14 inches (3 turns) white poster-board, cut 11.25 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking tape. Nozzle sealed with foam ear-plug, also covered with plastic-wrap and rubber band (it's raining!) |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.559 seconds |
| Burn time: | 0.641 seconds |
| Peak thrust: | 200 lbs (questionable) |
| Average thrust: | 134 lbs = 596 N |
| Thrust: | 86 lb-secs = 383 N-secs |
| Thrust curve: | Regressive curve with big dips |
| ISP: | 132 seconds |
| Impressions: | Strong burn overwhelmed the test stand, readings are rough approximations.
Big dips in the thrust curve are thought to be artifacts, rebound of over-stressed stand. |
I had not come to Cedarville expecting to be able to launch, but things worked out. My only airframe did not have electronic ejection, but was built to rely upon burn-through ejection. I have not yet developed this aspect of these reloads.
Stuart Leslie had some Aerotech delay charges and offered to let me use them. Since this was a new thing with this propellant, we decided to perform a static-test prior to any launch attempt.
Primary concern was that it would not work, that pressure drop upon grain depletion would cause the delay element to go out, or that leakage would occur at the delay element causing premature ejection.
Secondary concern was the length of the delay. We wished to time a full-length delay element, thus obtaining a point of reference for adjusting the flight motor.
A small charge of black powder was taped over the head end of the motor, in the depression provided for such a charge.
The motor was placed in a concrete block and wedged in with stones.
The head end was exposed to view from the left side. Stuart stood
with a stopwatch to time the delay.
Click here for a video of this static test
(beware:
2.5 meg file for 15 seconds of rather dull video)
It is a good thing that Stuart used the stopwatch, as the delay lasted longer than my video camera can make movies. The burn was normal, the delay was 13 seconds, and fired the ejection charge as planned.
Launch (1.7 meg download, 4 seconds of video) |
Recovery (5.4 meg download, 15 seconds of video) |
Not seen on video, ejection occurred just after apogee, calculated as 1575 feet which seems consistent with observations. Airframe is recovered undamaged.
| Designation: | 11/23/02A |
| Purpose: | Test duct tape as possible inhibitor |
| Propellant: | Recrystallized KN/SU, 9/2/02A, 13 inch burn rate at 1 atmosphere |
| Grain Type: | 2 Bates grains with new inhibitor |
| Grain Length: | 1.8 inches each, average |
| Grain outside dia: | 1.188 inches (propellant only) 1.27 inches with inhibitor |
| Core diameter: | 3/8 inch dowel, thus about 0.39 inches |
| Grain weight: | Bare grains: 106g, inhibited grains: 116.5g Thus inhibitor is about 10% of grain weight. |
| Inhibitor: | 3 layers of duct tape, Nashua 357 |
| Nozzle: | Phenolic, new, throat = 0.292 inch dia. |
| Kn Ratios | Initial: 123 Max: 140 Final: 112 Max PSI = 400 |
| Case liner: | 10 inches (2 turns) white poster-board, cut 3.875 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking
tape.
Nozzle sealed with foam ear-plug. |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.719 seconds |
| Burn time: | 0.92 seconds |
| Peak thrust: | 40 lbs |
| Average thrust: | 22.3 lbs = 99N |
| Thrust: | 21.4 lb-secs = 95 N-secs |
| Thrust curve: | Progressive/Regressive with big spike at end of burn |
| ISP: | 92.5 seconds |
| Impressions: | Low ISP probably due to low Kn ratio. Scary spike at end of burn is considered due to inhibitor being ejected and thus plugging the nozzle throat for an instant. Thus duct tape is not considered a good candidate for further experiments. But since it appears to have been an effective inhibitor, other tapes may be tried. |
| Designation: | 11/24/02A |
| Purpose: | Test aluminum foil tape as possible inhibitor |
| Propellant: | Recrystallized KN/SU, 9/2/02A, 13 inch burn rate at 1 atmosphere |
| Grain Type: | 2 Bates grains with new inhibitor |
| Grain Length: | 1.9 inches each, average, including inhibitor (a bit too long, nozzle retainer gap = 0.06 inches) |
| Grain outside dia: | 1.192 inches (average, propellant only) 1.237 inches with inhibitor |
| Core diameter: | 3/8 inch dowel, thus about 0.39 inches |
| Grain weight: | Bare grains: 104.7g, inhibited grains: 115.2g Thus inhibitor is about 9% of grain weight. |
| Inhibitor: | 20 inches of aluminum foil adhesive tape forming 5 layers (Nashua, .0045 inches thick) |
| Nozzle: | Phenolic, throat = 0.32 inch dia. |
| Kn Ratios | Initial: 105 Max: 121 Final: 97 Max PSI = 250 |
| Case liner: | 10 inches (2 turns) white poster-board, cut 3.875 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking
tape.
Nozzle sealed with foam ear-plug. |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.841 seconds |
| Burn time: | 0.92 seconds |
| Peak thrust: | 50 lbs |
| Average thrust: | 24.42 lbs = 108.6 N |
| Thrust: | 22.47 lb-secs = 99.94 N-secs |
| Thrust curve: | Slightly regressive |
| ISP: | 97.4 seconds |
| Impressions: | Low ISP probably due to low Kn ratio. Inhibitors recovered from fired motor are distorted (longitudinal crease) but intact. Inhibition was deemed effective, at least in this low-intensity motor. |
| Designation: | 11/28/02A |
| Purpose: | Test wax coating as moisture barrier, hopefully not ignition inhibitor |
| Propellant: | Recrystallized KN/SU, 10/24/02A, 10 inch burn rate at 1 atmosphere |
| Grain Type: | 2 Bates grains with poster-board inhibitor, made 10/24/02 and sealed,
in good shape, dry.
Dipped 3 times in melted paraffin, creating a heavy wax coating |
| Grain Length: | 1.91 inches each, average, including inhibitor & wax |
| Grain outside dia: | 1.2 inches (estimate, propellant only) 1.33 inches with inhibitor and wax |
| Core diameter: | 3/8 inch dowel, thus about 0.39 inches, narrowed to 0.3 inches by wax coating |
| Grain weight: | Bare grains: estimated at 104g, finished grains: 121.4g Thus inhibitor & wax is about 14% of grain weight. |
| Inhibitor: | 2 layers of poster board, glued on with epoxy |
| Nozzle: | Phenolic, throat = 0.32 inch dia. |
| Kn Ratios | Initial: 106 Max: 124 Final: 101 Max PSI = 300 (probably not, see below) |
| Case liner: | 10 inches (2 turns) white poster-board, cut 3.875 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking
tape.
Nozzle sealed with foam ear-plug. |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 1.44 seconds |
| Burn time: | 1.2 seconds |
| Peak thrust: | 25 lbs |
| Average thrust: | 15.3 lbs = 68 N |
| Thrust: | 18.36 lb-secs = 81.7 N-secs |
| Thrust curve: | Slightly progressive |
| ISP: | 80 seconds |
| Impressions: | Low ISP probably due to both low Kn ratio and slow burn, creating lower pressure than tables suggest. Slightly progressive burn may be due to slow ignition of end-faces between grains. |
Click here for video of static test (800k
file, 5 seconds of video)
Click here for spreadsheet analysis (Excel
format)
| Designation: | 11/29/02A |
| Purpose: | Test single grain with wood plug to fill case. Also second test of paraffin coating as moisture barrier, hopefully not ignition inhibitor. |
| Propellant: | Recrystallized KN/SU, 9.2/02A, 13 inch burn rate at 1 atmosphere |
| Grain Type: | 1 Bates grain, inhibited with aluminum foil tape, dipped once in melted paraffin |
| Grain Length: | 1.945 inches, including inhibitor & wax |
| Grain outside dia: | 1.25 inches (estimate, propellant only) 1.33 inches with inhibitor and wax |
| Core diameter: | 3/8 inch dowel, thus about 0.39 inches, narrowed to 0.36 inches by wax coating |
| Grain weight: | Bare grain: estimated at 62.9g, finished grains: 69.2g (one coat wax = 1.5g, 20 inches foil tape = 4.8g) |
| Inhibitor: | 20 inches of aluminum foil tape |
| Nozzle: | Phenolic, throat = 0.25 inch dia. |
| Kn Ratios | Initial: 92 Max: 107 Final: 86 Max PSI = 250 (probably not, see below) |
| Case liner: | 5 inches (1 turn) white poster-board, cut 3.875 inches wide. |
| Ignitor: | Electric match with 1/4g black powder & pinch of Mg flakes in masking tape. |
| Mounted on: | Analog test stand B, recalibrated in pounds |
| Ignition delay: | 0.439 seconds |
| Burn time: | 1.281 seconds |
| Peak thrust: | 26 lbs |
| Average thrust: | 15.6 lbs = 69 N |
| Thrust: | 18.36 lb-secs = 88.9 N-secs |
| Thrust curve: | Near-symmetrical, very slightly progressive |
| ISP: | 144 seconds |
| Impressions: | High ISP is probably due to inaccuracy of test stand at low thrust
levels. Nice curve, though.
Ignition was quick despite wax coating. Grain had sat out overnight with no apparent degradation. Humidity is low, so this is not the best time to test this feature. |
Click here for video of static test (800k
file, 5 seconds of video)
Click here for spreadsheet analysis (Excel
format)
| Designation: | 12/8/02B |
| Purpose: | Test of single grain in 2-grain casing, wood plug used to fill case. This is the third test of paraffin coating as moisture barrier, hopefully not ignition inhibitor. First use of "sparkle-match" ignitor and readjusted Test Stand B with relocated fulcrum to accommodate lower-power motors. |
| Propellant: | Recrystallized KN/SU with 1% Fe203, 6 second per onch burn rate at 1 atmosphere |
| Grain Type: | 1 Bates grain, inhibited with 3 layers aluminum foil tape, dipped twice in melted paraffin, one week old. It is still solid, no weeping is observed. |
| Grain Length: | 1.975 inches, including inhibitor & wax |
| Grain outside dia: | 1.25 inches (estimate, propellant only) 1.298 inches with inhibitor and wax |
| Core diameter: | 3/8 inch dowel, thus about 0.39 inches, narrowed to 0.36 inches by wax coating |
| Grain weight: | Bare grain: estimated at 56.7g, finished grains: 62.7g (one coat wax = 1.5g, 12 inches foil tape = @3g) |
| Inhibitor: | 3 layers of aluminum foil tape, about 12 inches |
| Nozzle: | Phenolic, throat = 0.216 inch dia. |
| Kn Ratios | Initial: 115 Max: 132 Final: 105 Max PSI = 300 |
| Case liner: | 9 inches (2 turns) blue/yellow poster-board, cut 3.75 inches wide. |
| Ignitor: | "Sparkle-match" - new ignitor design, designed to be inserted through small nozzle throat with little danger of clogging upon ignition. It is a section of black match with magnesium flakes, loosely covered in masking tape. Bridge wire is inside tape at one end, just outside nozzle. 1/2 inch of match is exposed at the other end, at head-end of grain. Functions like quickmatch: flame is conveyed through loose covering very quickly to head end. Mg burns through wax. |
| Mounted on: | Analog test stand B, Readjusted with new fulcrum about 1 foot from anchor for greater sensitivity, recalibrated with iron barbell weights. |
| Ignition delay: | 1.16 seconds |
| Burn time: | 0.96 seconds |
| Peak thrust: | 24 lbs |
| Average thrust: | 11.3 lbs = 50 N |
| Thrust: | 10.8 lb-secs = 48.1 N-secs |
| Thrust curve: | "Matterhorn" peak, near symmetrical curve but with slow build-up and tail-off |
| ISP: | 86.6 seconds |
| Impressions: | Low ISP may be due to inaccuracy of test stand, and to some degree low Kn ratios. Smaller nozzles are needed to test single grains. Slow build-up to peak thrust thought due to wax coating which may retard ignition, perhaps more between grains. Al foil inhibitor is intact after burn. |
Jimmy Yawn
jyawn@sfcc.net
12/8/02