XRV Rocket Chronicles

TRA #6539 L2

 Introduction
 Overview
 Development
 Propulsion
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 Avionics
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Author:
Steve Baughman

Web Updated Aug 27
© 1999
All Rights Reserved.

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IF YOU AREN'T FLYING YOUR PROJECT IS STANDING STILL

FLIGHT TESTING

  XRV Mk. I
High altitude flights require a good eye and clear skies.
 Photo by Gary Estes

Most folks agree that building rockets is a lot of fun. It can take days, weeks, even months or years to design and construct your project. It becomes a labor of love, and you, as chief engineer typically can't help but become more and more attached to your rocket as you watch your pile of parts gradually evolve into a unified and elegant whole. It's wonderful, but the more attached to one's rocket one becomes, the more one begins worry about what will happen on the day when you blast your baby deep into the blue sky. After all, you won't be along for the ride. "Who's going to look after my baby?"

I'm here to provide some advice: get over it! You built it to fly and fly it you should. It's a rocket, not a monument, so if you aren't going to fly it maybe you should bronze it and put it on a pedestal out in your front yard. Sure, propellant and hardware can get expensive, and the winds are not always perfectly condusive to launching, but for gosh sakes don't be one of those rocketeers who never flies.

I offer that advice because flying your rocket is what this is all about. The adrenaline buzz one gets just prior to lighting that candle can be formidable, and as you realize that it's your engineering prowess vs. the laws of physics, you might find that you can get pretty well lit too. The suspense is marvelous, and if your rocket thinks you did a good job, it will come back to tell you about it.

In this section we present the results of our first year of flight tests and beyond.

Checkerboard

XRV FLIGHTS AND TEST RESULTS

 "Wind? What wind?" - Assurances from Mark Carlson, the most fearless and prolific rocketeer I know.

The more you fly, the more you learn about what works and what doesn't. Along the way, you'll likely be blessed with advice from other experienced rocketeers about this and that, and that can help to lower the slope of the learning curve somewhat. As long as you are flying and not just camping, you'll find that you can come up to speed pretty quickly. Sure, you may have to do some walking, and you may have to dig soot out from under your fingernails on Monday morning, but at least you will have learned something along the way. And that will help you to prepare for next time.

In the first two blue lines on each of the matrices which follow, we present site environmental conditions at the time of launch, followed by vehicle, payload, and motor configuration. At the lower left are four values in grey which were calculated through simulation, denoting acceleration (Gmax), velocity (Vmax), altitude (Amax), and launch rod velocity (LRV). For launches which involved a data recording payload, a set of four empirically measured values are shown in green, denoting acceleration (Gmax), velocity (Vmax), and two altitude measurements, one using integrated acceleration values (AmaxA), and the final and more accurate altitude reading (AmaxP) from converted air pressure values. We rely on AmaxP to be the 'last word' regarding altitude. Finally, an occasional debriefing statement will show what was learned and what was improved upon.

 Flight 1
Date Event Location Elev Temp Wind
7/25/98 Heart of Texas 98 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk I n/a 48 oz 38/240 H123W-M10 211.4 Ns 66% H 2.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
7.5 g m 0.28 1291 ft n/a n/a n/a n/a n/a
  Table 7-1   All systems functioned nominally, received TRA level 1 certification.
 
 Flight 2
Date Event Location Elev Temp Wind
7/26/98 Heart of Texas 98 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk I n/a 48 oz 38/240 H242T-M10 234.2 Ns 73% H 1.2 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
16.7 g m 0.35 1464 ft n/a n/a n/a n/a n/a
  Table 7-2   All systems functioned nominally.
 
 Flight 3
Date Event Location Elev Temp Wind
7/26/98 Heart of Texas 98 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk I n/a 48 oz 38/360 I161W-M10 333.5 Ns 52% I 2.2 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
12.2 g m 0.41 2039 ft n/a n/a n/a n/a n/a
  Table 7-3   Long delay caused high speed deployment; broken shroud lines, minor zipper.
 
Much was learned during this time about motor assembly and rocket construction techniques. It became apparent on flight 3 that motor-delay style ejection can be unreliaby timed, and factory recovery systems can be stressed to the breaking point by the resulting high speed deployment. The stock elastic shock cord and parachute were scrapped, and replaced by nylon strapping with quicklink ends and a more durable parachute. The glued-on recovery mount was cut away and replaced with a combination baffle unit and recovery mount. The original motor retainer was removed and upgraded with Romex clips. The airframe was fiberglassed, and a rudimentary telemetry unit was installed into the previously empty payload bay. The XRV Mk II was now ready for action.
 
 Flight 4
Date Event Location Elev Temp Wind
9/5/98 N Texas Hi Power 13 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk II TMU1 96 oz 38/360 I357T-M10 341.0 Ns 53% I 1.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.4 g m 0.28 1347 ft 70 fps 10.4 g (e) m 0.14 (e) 658 ft (e) 1233 ft
  Table 7-4   Nominal flight, however accelerometer vibration caused telemetry errors (e).
 
 Flight 5
Date Event Location Elev Temp Wind
9/6/98 N Texas Hi Power 13 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk II TMU1 96 oz 38/480 I154J-M10 385.3 Ns 60% I 3.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
5.2 g m 0.23 1417 ft 40 fps no data no data no data no data
  Table 7-5   Flight and recovery nominal, however all data was lost perhaps due to TMU vibration.
 
 Flight 6
Date Event Location Elev Temp Wind
9/6/98 N Texas Hi Power 13 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk II TMU1 96 oz 38/480 I211W-M10 440.5 Ns 69% I 2.2 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
11.3 g m 0.32 1829 ft 57 fps 9.2 g (e) m 0.22 (e) 1688 ft (e) 1849 ft
  Table 7-6   Nominal flight, however accelerometer vibration caused telemetry errors (e).
 
 Flight 7
Date Event Location Elev Temp Wind
9/6/98 N Texas Hi Power 13 Windom, TX 700 ASL 100 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk II TMU1 96 oz 38/600 I284W-M10 554.2 Ns 87% I 1.8 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.41 2411 ft 68 fps inc data inc data inc data inc data
  Table 7-7   Nominal flight, however accelerometer vibration rendered data incomplete.
 
It was clear at this time that the structural upgrades had gone well, however the avionics package (TMU) had a few loose components that introduced vibration into the accelerometer and at times shorted system power. This was fixed with a generous application of cyanoacrilate and some rewiring. To more closely determine motor-delay recovery accuracy, failsafe sensors were added to the payload which recorded recovery deployment. The TMU software was modified with a new algorithm to detect apogee and ground proximity during flight, though at this time these events were simply logged and not acted upon. Finally, a one-touch arming feature was added to the TMU to increase safety and ease of use.
 
 Flight 8
Date Event Location Elev Temp Wind
12/6/98 Paradise 1 Eden, TX 1900 ASL 65 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk III TMU2 109 oz 54/852 J275-M10 818.7 Ns 64% J 3.2 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
7.8 g m 0.48 3215 ft 51 fps 6.5 g m 0.48 3623 ft 3390 ft
  Table 7-8   All systems functioned nominally, TRA level 2 certification.
 
Flight 8 marked a couple of significant milestones, first of all a new certification level was reached, but most importantly the TMU produced the first solid flight data during this flight. The new apogee and ground proximity detection algorithms worked perfectly, but it was decided that further testing of these capabilities would be prudent before implementing full dual deployment.
 
 Flight 9
Date Event Location Elev Temp Wind
12/14/98 Skye Dance XIII Kimbro, TX 650 ASL 65 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk III TMU2 109 oz 54/852 J180T-M10 825.8 Ns 65% J 4.5 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
8.4 g m 0.43 3277 ft 55 fps 8.4 g m 0.43 3392 ft 3492 ft
  Table 7-9   All systems functioned nominally.
 
 Flight 10
Date Event Location Elev Temp Wind
12/14/98 Skye Dance XIII Kimbro, TX 650 ASL 65 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk III TMU2 109 oz 54/852 J460T-M10 812.7 Ns 63% J 1.9 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.52 3234 ft 70 fps 10.6 g m 0.33 3669 ft 3081 ft
  Table 7-10   Short delay caused high speed deployment; accelerometer spike on deployment.
 
With two more solid flights complete, it was now time to install all of the upgrades supporting dual deployment. A forward main parachute bay was added, a drogue chute was installed in what was previously the main chute bay, and the Pyro Ignition Module (PIM) was added to support the firing of explosive deployment charges. This brings the vehicle up to the Mk IV configuration, with a payload consisting of the TMU3 and the PIM1.
 
 Flight 11
Date Event Location Elev Temp Wind
1/30/99 Skye Dance XV Kimbro, TX 650 ASL 65 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/852 J460T-M10 812.7 Ns 63% J 1.9 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
10.6 g m 0.40 2555 ft 60 fps no data no data no data no data
  Table 7-11   Flight data was lost due to user error; minor recovery failure; quicklink broke.
 
Though this first dual-deployment flight showed that the recovery system electronics and PIM were working, a quicklink failure caused the nosecone to fall free of the main parachute. It was recovered undamaged, and in response to this, all quicklinks were replaced by stainless steel carabiners. Also, the data from this significant flight was lost again by failing to power down the avionics prior to connecting the serial cable for downloading. Though it was never expected to be a problem, this instance confirmed that it is an issue which should be avoided by appropriate power management during downloading.
 
 Flight 12
Date Event Location Elev Temp Wind
2/13/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 0 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/852 J275W-M10 818.7 Ns 64% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
5.9 g m 0.37 2482 ft 44 fps 5.7 g m 0.28 2600 ft 2568 ft
  Table 7-12   All systems functioned nominally; noted accelerometer spike on deployment.
 
 Flight 13
Date Event Location Elev Temp Wind
2/13/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 0 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J415W-L14 1201.3 Ns 94% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
9.3 g m 0.50 3950 ft 54 fps no data no data no data no data
  Table 7-13   Nominal flight; however flight data was lost due to user error.
 
 Flight 14
Date Event Location Elev Temp Wind
2/13/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 0 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J800T-L14 1264.8 Ns 99% J 1.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
22.6 g m 0.62 4226 ft 89 fps 11.6 g m 0.44 4057 ft 4622 ft
  Table 7-14   All systems functioned nominally.
 
 Flight 15  data plots
Date Event Location Elev Temp Wind
2/13/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 0 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K550W-L14 1594.5 Ns 62% K 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.65 5218 ft 71 fps 10.8 g m 0.53 6007 ft 6060 ft
  Table 7-15   All systems functioned nominally.
 
 Flight 16  data plots
Date Event Location Elev Temp Wind
2/14/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 5 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J415W-L14 1201.3 Ns 94% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
9.3 g m 0.50 3950 ft 54 fps 9.2 g m 0.42 4318 ft 4417 ft
  Table 7-16   All systems functioned nominally.
 
 Flight 17  data plots
Date Event Location Elev Temp Wind
2/14/99 N Texas Hi Power 14 Windom, TX 700 ASL 65 F 5 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K550W-L14 1594.5 Ns 62% K 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.65 5218 ft 71 fps 11.6 g m 0.53 5774 ft 5649 ft
  Table 7-17   All systems functioned nominally.
 
North Texas High Power 14 was truly a golden weekend for rocketry, with low winds and a lot of great flights. Again on flight 13, data was lost due to failure to power off the TMU prior to serial downlaoding. This issue is perhaps the most frustrating of those experienced during the avionics development accomplished so far. Thankfully, five of six flight accomplished over the weekend produced beautiful flight data.
 
 Flight 18  data plots
Date Event Location Elev Temp Wind
2/27/99 Paradise 2 Eden, TX 1900 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/852 J460T-L14 812.7 Ns 63% J 1.9 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
10.6 g m 0.40 2555 ft 60 fps 6.1 g m 0.29 2260 ft 2260 ft
  Table 7-18   All systems functioned nominally; noted pressure spike on deployment.
 
 Flight 19  data plots
Date Event Location Elev Temp Wind
2/27/99 Paradise 2 Eden, TX 1900 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J800T-L14 1264.8 Ns 99% J 1.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
22.6 g m 0.62 4226 ft 89 fps 9.6 g m 0.42 4107 ft 4006 ft
  Table 7-19   All systems functioned nominally.
 
 Flight 20  data plots
Date Event Location Elev Temp Wind
2/27/99 Paradise 2 Eden, TX 1900 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K1100T-L14 1618.9 Ns 63% K 1.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
28.0 g m 0.76 5301 ft 94 fps 16.3 g m 0.53 4732 ft 5238 ft
  Table 7-20   All systems functioned nominally.
 
 Flight 21  data plots
Date Event Location Elev Temp Wind
2/28/99 Paradise 2 Eden, TX 1900 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J415W-L14 1201.3 Ns 94% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
9.3 g m 0.50 3950 ft 54 fps 8.8 g m 0.42 4304 ft 4006 ft
  Table 7-21   All systems functioned nominally.
 
Paradise 2 provided a wonderful venue for more flight testing. We were pleased to finally burn the mighty Aerotech K1100T motor in the XRV Mk IV, which is the largest motor that it can contain. This accomplishment pointed towards a need for a new and improved, more powerful booster, and at this time the Mk V entered the planning stages. The Mk IV sustainted some rock damage on landing and was repaired.
 
 Flight 22  data plots
Date Event Location Elev Temp Wind
4/11/99 Skye Dance XVI Kimbro, TX 650 ASL 85 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J800T-X18 1264.8 Ns 99% J 1.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
22.6 g m 0.62 4226 ft 89 fps 12.4 g m 0.43 3268 ft 4109 ft
  Table 7-22   All systems functioned nominally; noted pressure spike on deployment.
 
 Flight 23  data plots
Date Event Location Elev Temp Wind
4/11/99 Skye Dance XVI Kimbro, TX 650 ASL 80 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K550W-X18 1594.5 Ns 62% K 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.65 5218 ft 71 fps 11.6 g m 0.53 6223 ft 5752 ft
  Table 7-23   All systems functioned nominally.
 
 Flight 24  data plots
Date Event Location Elev Temp Wind
4/17/99 Coleman Air Show Coleman, TX 1900 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1280 J415W-X18 1201.3 Ns 94% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
9.3 g m 0.50 3950 ft 54 fps 8.4 g m 0.42 4159 ft 4314 ft
  Table 7-24   All systems functioned nominally, however an updraft was noted in the data.
 
 Flight 25  data plots
Date Event Location Elev Temp Wind
4/17/99 Coleman Air Show Coleman, TX 1900 ASL 75 F 10 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K550W-X18 1594.5 Ns 62% K 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
14.1 g m 0.65 5218 ft 71 fps 10.8 g m 0.52 5661 ft 5649 ft
  Table 7-25   All systems functioned nominally.
 
 Flight 26  data plots
Date Event Location Elev Temp Wind
4/18/99 Skye Dance XVIa Kimbro, TX 650 ASL 75 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU3-PIM1 151 oz 54/1706 K1100T-X18 1618.9 Ns 63% K 1.6 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
28.0 g m 0.76 5301 ft 94 fps 17.1 g m 0.53 5258 ft 5135 ft
  Table 7-26   All systems functioned nominally.
 
After five more test flights at three differents events we concluded that the Mk IV and the TMU/PIM avionics designs were solid, as long as the TMU was powered off before plugging in the serial cable. After Skye Dance XVIa, construction on the new XRV Mk V booster was fully completed and it was ready for action. To support the longer ascents of the Mk V, the telemetry software was upgraded to provide 30 seconds of high resolution ascent, and was renamed TMU4 (software version 0.4). The Mk V was primed and ready for Paradise 3.
 
 Flight 27
Date Event Location Elev Temp Wind
5/16/99 Paradise 3 Eden, TX 1900 ASL 80 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU4-PIM1 151 oz 54/1280 J415W-X18 1201.3 Ns 94% J 3.1 s
Gmax Vmax Amax LRV Gmax Vmax AmaxA AmaxP
9.3 g m 0.50 3950 ft 54 fps no data no data no data no data
  Table 7-27   Nominal flight; however flight data was lost due to user error.
 
 Flight 28
Date Event Location Elev Temp Wind
5/16/99 Paradise 3 Eden, TX 1900 ASL 80 F 15 mph
Vehicle Payload Weight Casing Motor Impulse Rating Burn
XRV Mk IV TMU4-PIM1 151 oz 54/1706 K550W-X18 1594.5 Ns 62% K 3.1 s
Gmax Vmax Amax LRV Gmax Vmax