MEGA – Intimidator 5

Rocket outline

  • Rocket – Wildman Rocketry Intimidator 5, unmodified single stage filament wound glassfiber rocket
  • Motors – KILO 6 grain KNSB – 5.600Ns & KILO 6 grain KNDX – 5.700Ns
  • Payload – Beeline GPS tracker in the nosecone and Mobius 1080P action camera attached to the outside looking down
  • Documentation – NERO RSDS, SolidRocketMotor file & OpenRocket file.
  • Diameter: 131mm
  • Length: 2563mm
  • Weight fully loaded as-built: 23500gr of which 4685gr propellant
  • Cd derrived from flight data: 0,56
  • Motor actuals after flight: KILO 6 grain KNSB Total impuls & Isp from flight data: 5600Ns. Isp 119,7s


  • Fly the newly develloped 90mm KNSB motor(s) without vastly exceeding the 2,0km wavier.
  • Sub-goals:
    • Built and fly a stock Intimidator 5 – learn HPR construction techniques.
    • Determine performace of the new KILO 6G KNSB motor (not static tested yet)
    • Derrive actual Cd of 72″ toroidal shaped Iris parachute and for log for future use.
    • Test dual stage recovery set-up.

Flight 2 Intimidator 5 – Friday 19.09.2014

  • To cope with the delayed deployment of the main parachute during fligt 1, (main was designed to be pulled out of the deployment bay by a drogue chute) the recovery lay out was revised. For this flight the 72″ Iris chute was folded according to Fruity chutes instructions and Z-folded into quarters. Parachute laid on the z-folded shock cord. Width of z-fold equal to the short side of an A4 paper. Parachute and shock cord burrito wrapped in kevlar and inserted into the airframe. Burrito OD was a loose fit in the airframe and nose cone eadily fitted (not needed to apply pressure) as with flight 1.

Flight 1 Intimidator 5 – Friday 16.05.2014

To be updated. The Intimidator 5 reached an  altitude of 1841m at a peak velocity of 207 m/s or 745km/h.



Post flight analysis

  • Not available

Design & Construction

Motor – KILO 6G  KNSB:

Actual stack length (6grains)= 810mm. Length motor chamber 820mm; liner length 818mm; clearance 2mm.

20140330 –Determined grain sequence fore the flight I. Nozzle to forward closure. Grain closest to the nozzle has highest density grains because more gasses travel through its core (copes better with erosive burning – although none is really expected).

  • Nozzle ↓
    • VI
    • V
    • IV
    • III
    • II
    • I
  • Forward closure.

Grain preparation:

Cleaned ends of KNSB grain with a piece of cloth & thinner and giving it a rub. Top grain core sealed with KN infused coffee paper. Red cap of BP container Ø45mm used as a cut out template. Glued KN infused coffee paper with thin line of white wood glue on the perimeter of the core on the KNSB. Used piece of cloth folded couple of times to apply pressure while under foot for 3-5 min. No wax paper in between but do not use too much glue to or apply the glue too wide as the glue will stick to the cloth.

10 gr BP was ground with a mortar and pestle for coating the 6 KNSB grains. The BP was places in an egg cup and isopropanol alcohol was added. Subsequently the slurry was brushed onto grain ends with a short 10mm round stipple paint brush. Final added BP mass per grain:

  • I. 814.5 –Unknown (contains the 10+10gr BP / Mg ignition mixture)
  • II. 813.4 – 815.0 = 1.6gr BP
  • III. 821.1 – 822.8 = 1.6 gr BP
  • IV. 827.1 – 828.7 = 1.6 gr BP
  • V. 827.6 – 829.3 = 1.7 gr BP
  • VI. 824.1 – 825.6 = 1.5 gr BP

10gr BP and 10gr Mg was put on top of grain. Grain was sealed with piece of office paper glued to casting tube with white wood glue. A piece of G10 plate was used in conjunction with a 5kg mass object to press the paper into the glue for 3-5min. After which set upside down to cure on its own weight.

Cutting the EDPM liner:

  • Length chamber = 820mm. – 2mm tolerance = 818mm.
  • Width ID chamber x 1,2 = 80 • π • 1,2 = 301mm.
  • Dimension liner: 818x300mm. Diagonal 870mm.

Average coating on the grains (pinch of NC lacquer combined with isopropanol and meal powder. 0,4gr – all surfaces painted. Total coating 3,4gr.

Average grain length: 118,5mm. Average grain density (actual/ideal): 97%. Average grain mass: 781,8gr. Core diameter 25mm.

Flight 2 KILO 6G KNDX motor


  • “Stack”, loaded with coated grains including liner – 5302gr. (Liner only, taped up – 288gr)
  • Nozzle excluding o-rings – 822gr
  • Nozzle retainer – 336
  • Casing – 3234gr
  • Forward bulkhead excluding o-rings – 294gr
  • Retaining ring – 87gr
  • Adapter ring 98x4mm – 63gr
  • 4-pcs O-ring – 35gr
  • 24pcs M5x12 counter sunk bolt – 48gr
  • Total mass motor: 10.221gr.

Stack length 816mm, slightly shorter than the expected 818mm. Some additional RTV sealant adviced. Cg of motor is 500mm from top (total length 935mm).


Fin can:

Rubber well nut M6 and use a M6x25 bolt – works very well for securing the rail buttons.

Body tube:

Performance Rocketry G12 base material – airframe tubing


Main toroidal parachute is a 72″ / 1800mm Iris Fruity chute with a Cd of 2,2. Parachute is attached to a 6mm D-shackle which is connected to a 40kN ball bearing swivel make Edelweiss or equivalent. For the main parachute a 12m long 1/2″ Kevlar shock cord is used. For the main parachute a water knot was tight into the cord 1m from the connection point to the avionics bay capturing the Kevlar burrito (700x600mm).

7gr 4F BP charges were used for both the apogee charge as well as the main parachute charge. 11gr BP back up charges

Tumble free fall equals an (fictive) hemispherical parachute of 0,6m diameter with Cd of 1,4.

Below mentioned values are derived from the Intimidator 5 descent actuals verified in flight I on 16-05-2014:

  • Tumble free fall Intimidator 5 rocket = 27,82m/s (918m in 33s)
  • Under 72″ Iris Fruity parachute  = 6,8m/s.
  • Rocket mass =  18,8kg (23,5- 4,685)


  • Big Red Bee GPS tracker – 100mW
  • Mobius camera shroud comes with #4 Self Tapping Screws pre-drilled with 2,5mm drill. Mounted shroud base 10mm from separation edge. Mobius recorded clip with a duration of 8:40min creates a file of 980Mb @ 1080p / 60Hz. Therefore a 16GB will record approximately 137min and will outlast the battery (80min according to the manual).