CCotner
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(First off-I decided to create my own account finally instead of using MuddAmateurRocketryClub's general account. I am the current president of MARC, and did this project under their auspices with CarVac.)
This is the "Mudd Team"'s entry into the N5800CS competition. We are flying ours at XPRS (pending no tragedies in the remaining construction process). It was designed to be such that we could build it ourselves (well, by myself mostly, but that's a different story) at Harvey Mudd College over the summer. It uses as many in-house-fabricated parts as possible, as we prefer working with our own processes and materials, especially given the ease with which the N5800 has shrugged off commercially-made nosecones/body tubes/fincans in the past. We are rising Seniors who will be graduating with bachelor's degrees in the spring; CarVac is an engineering major, and I am a physics major. This project represents what we are capable of in terms of design, analytical modeling, engineering judgement, and fabrication talent.
Starting at the bottom: a carbon fiber tailcone made with PTM&W 5712 high-temp high-strength epoxy that will snug over the thrust ring, retaining itself against the end of the nozzle and potentially retain the fincan at the back of the tube.
Fincan: machined aluminum, no welds. Fins machined from .25" 7075-T651 plate, with 8 degree (included angle) bevels. 3.25" span. Fins are heat-shrink-fitted into slots in the fincan, which is machined from a 6061-T6 extruded tube. FEM modeling (including approximations of heating effects) have shown that the shrink-fit will be sufficient to retain the fins against both dynamic pressure loading (axial, primarily) and flutter loading (transverse). In addition, the fins are retained by pressed-in alloy steel 3.32" diameter dowel pins in the fin roots, which (by hand analytical calculations) should also be able to retain the fin against estimated loads, even if there were no interference fit. The fincan will be heat-shrunk onto the motor case, and will be tied in to the tailcone over the thrust ring. The thrust ring of the motor case, however, is the largest diameter on the length of the rocket; there is no material over it.
Forward Anchor: a milled and turned aluminum body press-fits on the forward closure of the motor case. It uses a separate press-fit centering and alignment collet that presses onto the delay well fo the forward closure, and it bolts into the retaining stud on the motor case. It is pocketed out and contains a pair of Raven2 flight computers, independent Li-Poly batteries, a keychain HD camera and it's Li-Poly battery, three Featherweight screw switches, a hardpoint to tie the shock cord to, and a hardpoint that a Rattworks ARRD threads down onto. An aluminum cap screws down onto the top of it, covering the Raven and camera bays, creating an EM-resistant enclosure.
Forward Airframe: the commercially manufactured parts. A 13" long section of Hawk Mountain fiberglass coupler tube, with an internal 29mm tube by the same. They are retained on the aluminum anchor by a veritable panoply of recessed flathead screws in addition to being press-fitted over long shoulders in the aluminum. Contains a fiberglass (G10) av-bay which holds the GPS receivers, a Beeline 70cm (uBlox SIRF III) and a Beeline 900MHz (Trimble Lassen Iq), both with onboard data logging, and their batteries, and a switch to activate them.
(have class now-will add more later. link: https://docs.google.com/document/d/1HYh3MNpeld5GMWMje7R8VcdizjjysCkcC63Ja76DTB0/edit
This is the "Mudd Team"'s entry into the N5800CS competition. We are flying ours at XPRS (pending no tragedies in the remaining construction process). It was designed to be such that we could build it ourselves (well, by myself mostly, but that's a different story) at Harvey Mudd College over the summer. It uses as many in-house-fabricated parts as possible, as we prefer working with our own processes and materials, especially given the ease with which the N5800 has shrugged off commercially-made nosecones/body tubes/fincans in the past. We are rising Seniors who will be graduating with bachelor's degrees in the spring; CarVac is an engineering major, and I am a physics major. This project represents what we are capable of in terms of design, analytical modeling, engineering judgement, and fabrication talent.
Starting at the bottom: a carbon fiber tailcone made with PTM&W 5712 high-temp high-strength epoxy that will snug over the thrust ring, retaining itself against the end of the nozzle and potentially retain the fincan at the back of the tube.
Fincan: machined aluminum, no welds. Fins machined from .25" 7075-T651 plate, with 8 degree (included angle) bevels. 3.25" span. Fins are heat-shrink-fitted into slots in the fincan, which is machined from a 6061-T6 extruded tube. FEM modeling (including approximations of heating effects) have shown that the shrink-fit will be sufficient to retain the fins against both dynamic pressure loading (axial, primarily) and flutter loading (transverse). In addition, the fins are retained by pressed-in alloy steel 3.32" diameter dowel pins in the fin roots, which (by hand analytical calculations) should also be able to retain the fin against estimated loads, even if there were no interference fit. The fincan will be heat-shrunk onto the motor case, and will be tied in to the tailcone over the thrust ring. The thrust ring of the motor case, however, is the largest diameter on the length of the rocket; there is no material over it.
Forward Anchor: a milled and turned aluminum body press-fits on the forward closure of the motor case. It uses a separate press-fit centering and alignment collet that presses onto the delay well fo the forward closure, and it bolts into the retaining stud on the motor case. It is pocketed out and contains a pair of Raven2 flight computers, independent Li-Poly batteries, a keychain HD camera and it's Li-Poly battery, three Featherweight screw switches, a hardpoint to tie the shock cord to, and a hardpoint that a Rattworks ARRD threads down onto. An aluminum cap screws down onto the top of it, covering the Raven and camera bays, creating an EM-resistant enclosure.
Forward Airframe: the commercially manufactured parts. A 13" long section of Hawk Mountain fiberglass coupler tube, with an internal 29mm tube by the same. They are retained on the aluminum anchor by a veritable panoply of recessed flathead screws in addition to being press-fitted over long shoulders in the aluminum. Contains a fiberglass (G10) av-bay which holds the GPS receivers, a Beeline 70cm (uBlox SIRF III) and a Beeline 900MHz (Trimble Lassen Iq), both with onboard data logging, and their batteries, and a switch to activate them.
(have class now-will add more later. link: https://docs.google.com/document/d/1HYh3MNpeld5GMWMje7R8VcdizjjysCkcC63Ja76DTB0/edit