Level 3 Project Documentation

Project Description: scratch-built, 7.5 inch rocket with interchangeable motor mounts

Juggernaut : a massive inexorable force, campaign, movement, or object that crushes whatever is in its path.

I arrived at Whitakers at about 10AM Saturday December 18, 2004. I brought the rocket and my family in my RV because everything would not fit in my car.

I went out to the launch area to help set up the Unistrut rail, but Alan Whitmore and Paul Hoetjes had already finished most of the setup. Thanks Alan and Paul - one less thing to worry about! After a few minutes everything looked ready, so I went back to the rocket. I had not used the large rail or rail buttons before, so I walked the booster out to the rail and test-fit everything. It went on fine, but I learned that I had to raise the rail a bit to get the fins over the sawhorse that the rail is resting on.

I went back to the RV and began immediately preparing the rocket for launch. Occasionally, I remembered to actually look at my checklist. Soon after I started, my TAP mermbers arrived and I reviewed the rocket and documentation with them. I got the 3-part form authorization signatures, and went back to the rocket. Thanks again to Jim Livingston and Mark Lloyd for all their patient answers to my questions, their advice, and their time to inspect the rocket during construction and attend the launch! Here they are providing tremendous moral support.

I set up two folding chairs about 6 feet apart, and began assembling the rocket from the booster up. I installed the batteries in the Walston and installed the Walston in the booster. I then installed the lower airframe on the booster. I installed the drogue ejection charges into the electronics bay, and installed the electronics bay onto the lower airframe and installed the screws.

By this time, several of my friends and family had arrived and were asking lots of questions. So I took a short break from preparation and described the main components and operation of the rocket.

I then went back to preparation. I installed the main ejection charges in the electronics bay, and attached the upper airframe. I did a quick check of the electronics and ejection charge continuity. Into the upper airframe went the main parachute in its deployment bag, and the pilot/nosecone chute. Then with a little help, I put on the nosecone. The nosecone shearpins went in next, and then I did a final check of the electronics and continuity.

Now for the real business. I had assembled the motor - an Animal Motor Works M1850 Green Gorilla - and the igniter the night before. I removed the motor retention bolts, inserted the motor, and re-installed the motor retention bolts. I then filled out the flight card, and got RSO approval to launch the rocket.

A few sturdy friends were quickly summoned, and we carried the rocket out to the pad. Thanks to Donald Cox, Andrew Cox, and John Harter for helping to carry the rocket, and thanks to Matthew Wassel for carrying the igniter and Ben Cox for carrying the flight card! Then, with the help of several other folks including Alan Whitmore and Jim Livingston, we slid the rocket onto the rail and raised it to a secure position without breaking anything or hurting anyone. We took a few pictures and then cleared out all the spectators. I climbed the ladder was barely able to reach up to turn on the electronics, and listened for the proper cacophony of beeping from two happy altimeters. We then installed and secured the igniter, connected the leads, and did a continuity test which was very weak and turned out to be an omen.

Now we were ready - or so we thought. Alan Whitmore made a formal flight announcement and all spectators and camera crew were alerted. The spectators were lined up in a neat row in front of the RV. We did a nice long countdown, and then - nothing. We went out and did some figuring on the connections and wiring, and tried again. This time - nothing. We went back and did some more figuring, testing of cords and connections, and reasoned that the most likely remaining problem was a weak battery out at the away cell. Paul Hoetjes came to the rescue with a battery booster, which he connected in parallel with the existing battery.

The third time turned out to be a charm. After a less formal flight announcement and a short 5-count, the button was pressed and smoke was seen! The initial flame from the igniter was blue, and then the green propellant took over and the rocket ascended with a perfectly straight, strong, boost with a long and authoritative roar. After 3 or 4 short seconds, all my concerns about possible motor failure or failure of the airframe on its maiden voyage were alleviated. The nice AMW smoke grain kicked in, and we tracked the rocket all the way to apogee and saw separation. The wind was light, so the rocket fell almost straight down with the booster and airframe doing a bit of twirling and dancing in relation to each other, separated by the 50 foot shock cord. At just the right time, the nosecone was ejected, and moments later the pilot chute inflated and pulled the bag off the main chute. The main chute filled with air and slowed the booster and airframe, and the nosecone drifted slowly away with its own chute. Someone immediately began shouting excitedly. The rocket drifted majestically down to earth, and landed only about 300 or 400 feet away from the pad.

I ran out to the booster, and had to cross a swamp to get there. We gathered up the nosecone and booster/airframe, and found no damage. In fact, except for the black soot on the aft of the booster, it was hard to tell the rocket had even been launched. Donald, Andrew and I carried everything back. Approvals were made, forms were signed, and smiles were big. All in all, it was a textbook perfect launch.

I would like to thank all the friends and family who came to the launch, gave moral support, and took pictures: My family - Toni, Andrew, and Ben; my brother Donald and his wife Kristen; Robert and Lisa Uthe and their three children; Peter Wassel and his three sons; Kevin Dunphy and his son; and John Harter.

First fin laid 11/29/2003. The fins are nomex honeycomb composite, custom made to my design by Giant Leap Rocketry.

Add an inside liner of Kevlar to the booster and electronics bay couplers. You can also see the fiberglass layer on top of the carbon fiber on the body tubes. It covers up the pretty carbon fiber, but I'm going to paint it anyway.

Here is a nice picture of the booster construction. I added a layer of carbon fiber re-enforcement that runs up into where the exterior fin fillet will go. I have 4 allthread rods between the centering rings on both sides of the fins, to keep the aft centering ring in place. I also have mount points inside the aft centering ring for the bolts that hold the aft plate of the interchangeable motor mount in place. You can also see the brass tube for the airstart wires.

Here is a test-fit of the booster. You can see the t-nuts for the rail buttons bolts. Yes, it was hard lining up those holes, and yes, it was hard lining it up again after applying the carbon fiber and fiberglass wraps!

Epoxying the booster airframe to the fins. Note that the aluminum plate in the picture is actually part of the interchangeable motor mount, and is not epoxied in (it is included here to help retain the shape while clamping). The aft centering ring is behind the plate.

Here is a rear-view of the booster without the aft centering ring. You can see the internal epoxy fillets, and the mount points with t-nuts for the bolts that hold on the interchangeable motor mount. This is a 6" inner tube for the interchangeable motor mounts. The gap between the inner and outer tubes was filled with expanding foam before permanently installing the aft centering ring.

Here you can see the strips of 1/4" dowel that I cut in half and used for edges of the composite fins. You can also see the fiberglass aft centering ring that has now been epoxied into place.

I added a layer of carbon fiber and fiberglass on the fins from tip to tip. Here you can see the filler used to smooth it out in preparation for painting. You can also see the aft centering ring with the allthreads sticking out. The allthreads come all the way out past the interchangeable motor mount plate.

A couple of pictures of the electronics bay. I cut the bulkheads on my lathe from 3/4" birch plywood, and cut a shoulder so that 1/4" sticks into the coupler. The bay is held together by 4 1/4" allthread rods, which also serve as the mount point for the electronics board.

1. NAME: David Cox	ADDRESS: 2004 Lacebark Lane, Raleigh, NC 27613	PHONE #: 919-847-1546
TRA #:9280	LAUNCH LOCATION:Whitakers, NC	DATE:December 18, 2004
ROCKET SOURCE: KIT SCRATCH Scratch	ROCKET NAME: Juggernaut	COLORS: navy and burgandy
ROCKET DIAMETER: 7.5"	ROCKET LENGTH: 11.5'	ROCKET WEIGHT LOADED: 53 lb
AVIONICS DESCRIPTION:Primary PerfectFlite MAWD Secondary Ozark ARTS	MOTOR TYPE:AMW M1850GG	THRUST TO WEIGHT RATIO:9.1
LAUNCHER REQUIREMENTS:unistrut rail	LENGTH: 10'
CENTER OF PRESSURE: 32.8" from aft	HOW CALCULATED: VCP, Rocksim
CENTER OF GRAVITY: 48.5" from aft	HOW CALCULATED: Direct
MAXIMUM VELOCITY: 548 MPH	HOW CALCULATED: Markworld simulator
MAXIMUM ALTITUDE: 5900	HOW CALCULATED: Markworld simulator
WAS FLIGHT SUCCESSFUL:	YES: YES	NO:
TAP NAME:	Mark Lloyd
TAP NAME:	Jim Livingston
TAP NAME:

The rocket will launch from the unistrut rail. The altimeters will arm during initial ascent.

The rocket will ascend to 5900 feet, at which time the MiniAltWD altimeter will fire the drogue charge. The rocket will separate between the booster and upper airframe, and deploy the drogue parachute. The rocket will descend at approximately 75 feet per second.

The rocket will descend to 1300 feet, at which time the MiniAlt WD altimeter will fire the main charge. The rocket will separate by ejecting the nosecone, which will pull out the pilot chute and freebag with main parachute. The pilot chute will inflate and create a drag that will pull the main parachute lines out of the freebag, and then pull the main parachute out of the freebag. The nosecone, pilot chute, and freebag will immediately slow their descent, drifting away from the remainder of the rocket, and recover separately. The main parachute, once free of the bag and with the shroud lines already extended, will deploy orderly and slow the descent of the upper airframe and booster to approximately 20 feet per second.

Once the main airframe reaches 1000 feet, the ARTS altimeter will fire the backup main charge.

The time (horizontal) axis runs to 20.0 seconds. Each tick mark is 2.0 s
The blue trace is altitude. Full scale is 2000 meters. Each tick is 200 m
Burnout, apogee, and ejection are marked with black dots.
The green trace is airspeed. Full scale is 2000 meters per second. Each tick is 200.0 m/s
The red trace is thrust. Full scale is 5000 Newtons. Each tick is 500.0 N

Flight duration 382.1 seconds.
Max altitude = 1786.98 meters (5862.7 ft) at 18.2 seconds.
Peak speed = 245.22 meters per second (548.5 MPH).
Maximum acceleration = 10.26 g.
Turn over at 18.2 seconds
Chute deployment at 7.96 m/S, shock = 1.43 g.
Impact at 4.7 m/s.

Scratch-built 3FNC design, similar to a stretched Bruiser EXP with interchangeable motor mounts.

The airframe will be made of 7.5 inch flexible phenolic from Giant Leap Rocketry. The rocket will be approximately 11' 6" tall. I will use a fiberglass 3:1 ogive Performance Rocketry 7.5 inch nosecone. One of my goals is to use little or no nose weight; so I will consider making the rocket longer to achieve that goal. The rocket will be configured with a standard dual deployment configuration - booster with zipperless design, drogue bay, altimeter bay, main parachute bay, and nosecone with a small payload area. The airframe will be reinforced with a layer of 4.7 oz carbon fiber, followed by a layer of 8 oz fiberglass and a finishing layer of 3 oz fiberglass. All couplers will be internally reinforced with a layer of 5 oz kevlar cloth. My goal is a total rocket weight of about 45 pounds, including recovery system, but with the motor.

I purchased the airframe and motor tubes from Giant Leap Rocketry, the recovery components, motor casing and reload, and many other components from Magnum Rockets, and the nosecone and several other components from Performance Hobbies. I made most of the centering rings, the altimeter bay bulkheads, the booster and nosecone rings and bulkheads, and the aluminum aft plates on my lathe.

The booster will be 48" long to accommodate at least a 6400 NS 75mm case. The forward end of the booster will contain a 12" section of coupler, set half-way into the tube. At the forward end of the coupler, I will insert a centering ring with a 4" ID. I will screw a bulkhead plate over the centering ring with 6 10-32 titanium screws, and attach a 3/8" SS U bolt to the bulkhead plate. The bulkhead plate is removable for two reasons: one, so I can remove it and use a longer motor (extending out of the booster and into the drogue bay), and two so that I can remove it and use an experimental motor casing with an eyebolt for attachment rather than the U bolt on the bulkhead plate. In the #2 case (eyebolt attachment), the shock cord will go through the 4" ID centering ring.

The booster will contain 4 centering rings with ID of 6". A 6" phenolic tube will run through the centering rings, for the length of the booster section, all the way up to the 4" ID centering ring at the top of the booster coupler. Interchangeable motor mount assemblies will slide into the 6" phenolic tube with the aft end butting against the aft centering ring. The interchangeable motor mounts will have a 7.5" plate on the aft end that cantilevers against the rear 6" ID centering ring and the end of the 6" phenolic tube. The aft end of the motor mount assemblies will bolt onto the aft centering ring with 3 1/4" titanium bolts. The motor mount assemblies will consist of two centering rings that fit inside the 6" ID phenolic tube plus the aft ring which is 7.5" diameter and fits inside the main body tube. The 3" and 4" motor mounts will have a ½" plywood aft ring plus a 1/8" aluminum aft ring. The thrust of the motor will be focused on the “lip” of the motor mount assembly. The thrust will be distributed through all 4 booster centering rings via the 6" phenolic tube and the fins. The booster also includes three #10 allthread rods that span the centering rings on top and below the fins to ensure that the aft centering ring does not pull out. These allthread rods extend past the aft centering ring of the interchangeable motor mounts, and nuts are installed after the motor mount is slid into place. The booster also includes three additional #10 allthread rods that span the centering rings on top and below the booster coupler, to ensure that the forward bulkplate cannot pull out.

The booster also contains a mount point for a Walston transmitter in the booster coupler, with a tube for the antenna extending down into the booster. That section of booster is reinforced with a second layer of 8 oz fiberglass rather than carbon fiber, to prevent attenuation of the transmitter signal by the conductive carbon fiber.

The fins will be mounted through the outer airframe, and attached to the 6" phenolic tube, similar to the TWT design of a bruiser EXP. I will fillet the fin to inner tube joints and re-inforce with 8 oz fiberglass. I will also make internal and external fillets at the fin to outer tube joints. I will then fill the gap between the 6" tube and the 7.5" airframe, between the two centering rings nearest the fins, with expanding foam. I will drill a few small holes in the fins for the foam to fill into.

For the level 3 certification flight, a motor mount assembly will be constructed with a single 3" motor mount tube centered in 3 centering rings that fit into the 6" phenolic tube. Motor retention will be provided by 4 #10 t-nuts on the back side of the aft centering ring, with 4 10-32 titanium screws and SS fender washers holding the motor.

For subsequent flights, I also have a 4" motor mount and a cluster motor mount with a central 54mm surrounded by 6 38mm motors. The design will also allow a 115mm motor mount to be easily constructed and installed.

I will use a clipped delta fin shape, with the approximate surface area of the fins on the Bruiser EXP. I will use rocksim to ensure that the fins provide a comfortable level of stability. The fins are constructed of 1/4" nomex honeycomb edged with 1/4" wood dowels cut in half. I will re-inforce the fins with 5.7 oz carbon fiber tip-to-tip, followed with a 3 oz finishing layer of fiberglass.

The U bolts will be 3/8" stainless steel with backing plates and nuts on both sides. Quick-links for the parachute connections will be 3/8" stainless steel delta quick-links. All hardware is titanium or stainless steel, with sizes noted throughout the description. Most bulkheads and centering rings will be made of ½" birch plywood. The altimeter bay bulkheads are made of 3/4" birch plywood, turned on a lathe to form a 1/4" shoulder. Three of the booster 7.5" - 6.0" centering rings are 1/8" fiberglass. Epoxy will be West Systems slow, with binders, thickeners and fillers added for the appropriate application.

The electronics bay will be fashioned after the design I used for my Magnum. The bay will consist of a re-enforced 12" long coupler tube, with a 1" ring of airframe around the center. This results in a coupler on each end of the bay. The switches will be mounted in holes drilled through the center section of the bay, through the 1" section of airframe.

The bay will have two bulkheads on each end, one the to fit the OD of the coupler and one to fit the ID. The bulkheads are thus stepped, with part sliding into the bay and part resting on the outside. The aft bulkhead will be permanently attached to the bay. The forward bulkhead will be removable. The bay bulkheads will be held together by four 1/4" SS allthread rods. The allthread rods will be permanently anchored in the aft bulkhead, and will be secured to the fore bulkhead with wing nuts and washers.

The electronics board will be mounted on two sliding lugs that slide onto two diagonally opposed allthread rods that hold the bay together. The wires to the switches will be long enough that I can slide the electronics board all the way out of the bay without disconnection any wires. The electronics will not be accessible through an exterior panel; only be removing the upper body tube and removing the wing nuts and forward bulkhead.

The forward and aft bulkheads of the altimeter bay will be fitted with 3/8" SS U-bolts for connection of the shock cords.

Since the rocket separation points are at the booster coupler and at the nosecone, the body tubes that slide over the altimeter bay couplers must remain in place. Two #4-40 SS screws through the body tube and altimeter bay wall with backing nuts inside the altimeter bay will hold each body tube in place on the altimeter bay coupler.

I will use a Perfectflite MiniAlt WD altimeter as the primary and an Ozark ARTS altimeter as a backup. The MAWD is a barometric unit and the ARTS is an accelerometer based unit. I will configure the MAWD for drogue separate at apogee, and main at 1300'. I will configure the ARTS altimeter for a 1-second apogee delay, and the main at 1000'.

Each altimeter will be connected to a terminal block on the aft bulkhead for the drogue e-match connections. Each altimeter will be connected to a terminal block on the forward bulkhead for the main e-match connections. I will also include a terminal block on the aft bulkhead for future connections for airstarted motors. All holes through the bulkheads will be sealed with epoxy. All wires will be heat-resistant Teflon coated 20 gauge stranded copper wires.

The on-off switch will be a double-pole, double-throw key switch. In the On position, power from the batteries will be connected to the altimeters. In the Off position, the battery positive lead will be connected to an external 2.5mm jack for recharging without opening the altimeter bay.

The battery for the MAWD will be a re-chargeable 7.2V NiCad battery pack made from 6 2/3AA cells.

The battery for the ARTS (and for future airstart boards) will be a 9.6 volt NiMH pack made from eight 4/3 A cells. This pack can deliver 40+ amps and has a capacity of 4500 mah.

The apogee ejection charge will separate the rocket at the booster coupler and will release the 24" drogue. The backup altimeter will fire a second e-match in a second ejection charge. The primary charge will be 3.5g and the secondary charge will be 5.0g.

The main ejection charge will fire at 1300' and will separate the rocket at the nosecone. The ejection charge will eject the nosecone, pulling out the pilot which will pull out the deployment bag. The nosecone, pilot, and deployment bag will separate from the main parachute and recover separately. The main parachute lines will pull free of the deployment bag in an orderly fashion due to the drag of the pilot, and then the deployment bag will release the main parachute. With the lines fully extended, the main parachute will deploy and recover the upper airframe and booster. The descent rate under main will be about 18 feet per second. The primary charge will be 3.5g and the secondary charge will be 5.0g.

The nosecone is held in place by three 2.0mm styrene rods for shear pins. The shear pin holes in the body tube and nosecone are reinforced with thin brass tubing.

The shock cords will be 1" tubular nylon. I will use 50 feet for the drogue shock cord. The drogue parachute will be a 24" drogue from SkyAngle. I will use approximately 20 feet for the main shock cord. The main parachute will be a XL Cert-3 parachute from SkyAngle. The main parachute will use a deployment bag with a 36" pilot chute. The deployment bag and drogue will be attached to the nosecone and will recover separately under the pilot chute. The main parachute will recover the upper airframe and booster.

I will add a removable plywood bulkhead to the top of the nosecone coupler section. The bulkhead is attached with three 10-32 titanium bolts to a 4" centering ring that is permanently mounted in place in the nosecone. The nosecone interior is accessible through the 4" centering ring hole by removing the plywood bulkhead. The bulkhead has a SS 3/8" U-Bolt for attachment of the pilot chute and the strap to the deployment bag.

The payload area can be used for my GPS or to add nose weight if necessary. Nose weight will not be necessary for stability, but may be necessary to keep altitude to a reasonable level when using an N motor.

Name	Juggernaut
Weight	41 lb without motor
Launch weight	53 lb
Height	11.5 feet
L3 motor	AMW M1850GG
Successful?	YES
Alt	5600 feet
Electronics	dual deploy; MAWD and ARTS