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Spark-S4 Rocket

The team at Spark Rocket Labs has a goal to send a rocket with a 1kg payload past the Karman line and recover it. To reach that goal, we have an intermediate goal of designing and flying a minimum-diameter platform that can be used as a test bed for sustainer design. That platform is the SPARK-S4 rocket

The SPARK-S4 (Solid Propulsion & Ascent Research Kit - Sustainer 4in) Rocket is designed to be a modular, minimum-diameter system that breaks the fin can, motor tube, electronics bay, and recovery systems into separate systems that can be swapped and upgraded as necessary.

Length 78.5in
Weight w/o Motor 14lbs
Motor Mount 98mm Minimum Diameter
(Can adapt down to 54mm)
Body Material Filament Wound Fiberglass Tube
Filament Wound Fiberglass Nosecone
Fins 4 Fins
Aluminum Max-Q Fin Can
Avionics Primary Flight Computer: Blue Raven
Backup Flight Computer: Raven 4
Telemetry: Featherweight GPS Tracker
Cameras Forward Facing: Runcam Thumb Pro 2.7K@60fps
Rearward Facing: Runcam Thumb Pro 2.7K@60fps
Straight Facing: Runcam Thumb Pro 2.7K@60fps
Recovery Drogue: Rocketman Experimental Drogue 2ft
Main: Rocketman High Performance CD 2.2 Parachute
Ejection Charges: Tinder Rocketry Peregrine 12g
Main Explosive Bolt: Tinder Rocketry TD-2
Spark-S4 overview with no motors loaded. CG and Mass are actual numbers, not calculated.
Spark-S4 overview with no motors loaded. CG and Mass are actual numbers, not calculated.
Spark-S4 with the largest motor we will fly in it loaded up. The N1100 just fits and allows a direct connection to the av-bay retention bolt.

The sequencing below shows the basic recovery system components and function in cutaway picture form. Note that the payload airframe is not shown and the rest of the rocket below the recovery plate is hidden from view. Also, note these pictures are to illustrate the general concept of the recovery system and may not be an accurate representation of the final design.

SPARK-S4 Deployment

Recovery Systems Package Overview

The main shock cord is packed against the av-bay bulkhead. The main chute is packed in a deployment bag and that going in next. A 24in drogue chute is attached 5ft down from a 35ft long 1/4in tubular Kevlar harness. The end of the harness is connected to the TD-2 pin and the top of the main deployment bag. The main chute is attached to the end of a 10ft long 1/4in tubular Kevlar harness. The Kevlar harnesses are attached via 1/4in stainless steel quick links to 1 3/8in stainless steel eye bolts on the av-bay bulkhead and main bulkhead.

SPARK-S4 Deployment 2

At Apogee

At apogee, a 12g CO2 charge from the peregrine system will separate the nosecone from the payload tube/AV bay. There is a backup peregrine system that will fire 0.5 secs after the main peregrine charge fires. The nosecone is held in place with (3) #2-56 shear pins to prevent premature deployment.

SPARK-S4 Deployment 3


The two halves of the rocket will fall at an estimated 60 ft/sec until the barometric altimeter senses 700 ft AGL. The TD-2 still has the pin engaged at this time which keeps the drogue from pulling the main out and also keeps the rocket together.

SPARK-S4 Deployment 4

Main Release

At 700ft the Raven's fire an ematch in the base of the TD-2. That ematch drives a piston forward which releases the TD-2 pin. The drogue chute will pull the main chute in the deployment bag out of the body.

SPARK-S4 Deployment 5


The drogue chute continues to pull the deployment bag off of the main chute. The deployment bag allows for a quick gentle deployment. After deployment of the main chute, the booster portion rocket should descend approximately 16 ft/sec (estimated using manufacturer’s data and Rocksim analysis). The nosecone will descend separately under the drogue chute at approximately 20 ft/sec (estimated using manufacturer’s data and Rocksim analysis).