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“ The Other Woman ”. National Association of Rocktry Level Three Certification Project By Steve Laird NAR #86948. 7.5” Air Frame 112” Overall Length 98mm Motor Mount 60” Booster Section 30” Payload Section 15” Electronics bay Dual Altimeters. AMW M2500-GG Launch weight 50 lbs

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The other woman

The Other Woman”

National Association of Rocktry

Level Three Certification Project

By Steve Laird

NAR #86948


Design basics

7.5” Air Frame

112” Overall Length

98mm Motor Mount

60” Booster Section

30” Payload Section

15” Electronics bay

Dual Altimeters

AMW M2500-GG

Launch weight 50 lbs

11:1 Thrust ratio

6200’ Predicted

Design Basics


Flight operation
Flight Operation

The M2500-GG will boost for about 3 seconds and then the rocket will enter the coast phase it will reach about 6200 feet at apogee at which time the first apogee charge will fire followed by a delayed back up charge. The rocket will enter the recovery phase under a 48” Spherechute attached close to the E-bay with 50 ft of shock cord attaching it to the booster. At 1100’ the first Main charge followed by the back up charge at 1000’ will fire ejecting the nose cone and 14’ Spherechute packed in a deployment bag. The nose cone and bag will separate from the main thus deploying it and be returned by its own 36” Spherechute. At this point I will resume resperations and recover the rocket for post flight inspection.


Design concept
Design Concept

“The Other Woman” started as a LOC/Precision Bruiser EXP3. It was modified with a 98mm Motor Mount, extra centering rings, full electronics bay, and redesigned fins. The Nose cone will be modified with an internal bulkhead and hard point to increase payload space for recovery system and provide for addition of nose weight when needed. The entire rocket is laminated with two layers of 6 oz fiberglass and finished. Motor retention is a 98mm Aeropack retainer and 98-75mm Aeropack adapter. Recovery will be controlled by 1 Perfectflight MAWD and 1 Missleworks Mini RRC. Recovery will be standard Dual Deploy with “Free Bagging”. Hard points on E-bay and Booster consist of two 5/16” U-bolts in each location.



Construction overview
Construction Overview

  • All construction was done using West Systems Epoxy products.

  • Fiberglassing was done with Slow Cure.

  • Fillets done with Fast Cure and 405 filler.

  • Sandable filling done with Extra Slow Cure and 410 filler.

  • Joints done with Fast Cure.

  • Fiberglassing was done with fiberglass from Mr. Fiberglass and is one piece and two wraps on both tubes.


Booster construction
Booster Construction

The booster is constructed with 2 30” inch sections of LOC 7.5” body tubes coupled together with a 15” LOC coupler and then laminated with 2 wraps of 6 oz fiberglass. The motor mount is a 98mm 32 inch long section of LOC MMT and has 4 centering rings installed. The top centering ring has a smaller OD and is located inside the coupler, the next centering ring is installed against the bottom of the coupler, the third centering ring is located at the midpoint of the fins and the fins are notched to fit around this ring. These three rings are attached by 3 5/16” sections of all thread 2 5/16” u-bolts are attached to the top ring to connect the recovery harness. The bottom centering ring is attached to the the MMT and fins and has a 98mm Aeropack retainer.


Motor mount construction
Motor Mount Construction

Upper 3 centering rings are spaced 11 inches apart and use 3 lengths of 5/16” all thread to distribute thrust. Centering rings are attached to motor mount using West Systems Epoxy Products. Centering rings epoxied on both sides of joint and applied to threads to lock nuts in place.


Redesign to fins
Redesign to fins

The original fins were small and thin. I wanted to move my Center of Pressure further back to prevent the need for nose weight and improve stability with smaller motors. The new fins cross over one CR adding to positive transfer of thrust to all rings. The second and third CR are connected by both all thread and fin tabs.


Fin can construction
Fin Can Construction

The MMT dry fit to the Booster and used to help align and tack fins into position with epoxy. After the fins were tacked on the fin can was removed and a layer of 6 oz fiberglass was added from fin to fin. Fillets were added between the fins and MMT using a bonding additive for increased strength.

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Booster assembly
Booster Assembly

The fin can was mounted into the booster and reinforced. Strips of 6 oz fiberglass were laminated in place between the fins and the outside of the booster and filets installed

Then inside filets were added and the aft center ring was mounted to the finished assembly.


Electronics bay construction
Electronics Bay Construction

The electronics are housed inside a 15” coupler with a 14” LOC Stiffy Tube attached to the payload tube. Internally the bay has 4 5/16” sections of all thread and the electronics sled slides down two of these on the diagonal. Each of the bulkheads for the bay have a short section of PVC pipe installed with a passing hole to pass the ejection charge wires into the bay, each hole will be plugged with putty for flight. Inside the bay each altimeter has its own independent on/off switch and an on/off switch for the charges. The primary Altimeter will be a Perfect flight MAWD and the back up will be a Missile works Mini RRC. Both have previous flights and proven dependable.


Electronics bay
Electronics Bay

Uses 15 inch coupler, 14 inch “Stiffy” tube, ½” bulk plates, 5/16” all thread and 5/16” U-bolts. 4 16” sections of all thread attach both bulk heads together with 2 U-bolts at each end for hard points. Altimeter carrier is installed across the diagonal. It is constructed with Oak slides and ¼” Aircraft grade plywood.


Payload and nose cone construction
Payload and Nose Cone Construction

The payload is one 30” section of LOC 7.5” body tube and is laminated with two wraps of 6 oz fiberglass. The coupler that carries the Electronics bay is mounted to the aft end. Three 4” brass strips are laminated under the fiberglass to the forward end of the body tube in order to shear the shear pins that will be used to attach the nose cone for flight.

The nose cone was modified by cutting away the bottom end to allow for a bulkhead to be installed inside with a stronger mount point for the recovery harness.


Payload
Payload

Coupler installed and vent holes/switch access drilled.

Brass strips can be seen under the fiberglass these are to help break shear pins without damaging the body tube.


Recovery overview
Recovery Overview

Recovery will be Dual Deploy. A 4 foot drouge chute will be ejected at apogee and will be attached at the connection point between a 7 foot Kevlar yoke connected to the E-bay and the 50 foot tubular nylon shock cord going to the boosters 5 foot yoke. The main will be ejected at 1100 feet with back up at 1000 feet and will eject the nose cone that is attached to a deployment bag holding a 14 foot main the main is atached to the e-bay with a 7 foot Kevlar yoke. The deployment bag and nose cone will be recovered by their own 3 foot Pilot chute. All recovery components that are not Kevlar will be protected by 24”x24” Nomex blankets. Both Rocket sections have 3/16” vent holes to prevent early ejection. Descent rate is calculated at 16ft/sec.


Primary altimeter
Primary Altimeter

  • Perfect Flight MAWD

  • Barometric Sensing

  • 9V Battery for power

  • Independent Arm Switch

  • Independent Pyro Safety switch

  • Flash bulbs will be used to fire ejection charges


Secondary altimeter
Secondary Altimeter

  • Missile Works Mini RRC

  • Barometric Sensing

  • 9V Battery for power

  • Independent Arm Switch

  • Independent Pyro Safety switch

  • Flash bulbs will be used to fire ejection charges


Wiring schmatic
Wiring Schmatic

main

RRC2mini

miniAlt/Wd

main

Back up

Primary

Sw 4

Sw 3

Sw 4

drogue

drogue

Sw 3

main

switch

Sw 1

drogue

switch

drogue

battery

battery


Recovery components

Main Chute – 168” Spherechute in a Sky Angle XXL D-bag

Drouge Chute – 48” Spherechute

Pilot Chute – 36” Spherechute

2 24”x24” LOC Nomex Blankets

2 15’ 9/16” Kevlar shock cords from Giant Leap ( Loop tied at mid point) used as yokes to E-bay

5’ 1” tubular nylon booster yoke

50’ 1” tubular nylon shock cord

Recovery Components


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