From b116087c2380f81401464cf1101f898aa3d3b5f1 Mon Sep 17 00:00:00 2001 From: Bdale Garbee Date: Tue, 21 Apr 2015 12:34:08 -0600 Subject: [PATCH] new airframe project --- music/guitars/bdale-1/index.mdwn | 28 +++++- rockets/airframes/MehGaNuke/index.mdwn | 123 +++++++++++++++++++++++++ 2 files changed, 150 insertions(+), 1 deletion(-) create mode 100644 rockets/airframes/MehGaNuke/index.mdwn diff --git a/music/guitars/bdale-1/index.mdwn b/music/guitars/bdale-1/index.mdwn index 00ef3ab..fb1f495 100644 --- a/music/guitars/bdale-1/index.mdwn +++ b/music/guitars/bdale-1/index.mdwn @@ -28,7 +28,7 @@ a really good thing! ## Part Selections ## -Another intense period of study led to the decision to use +A period of intense study led to selecting [DiMarzio](http://dimarzio.com) Area pickups. These are stacked-coil hum reducing pickups in the standard strat single-coil pickup form factor. The chosen "standard" set consists of: @@ -71,6 +71,32 @@ Canadian maple neck purchased from eBay seller "bluelink88". |guitarheads.net||||| |black hard tail bridge||1|16.99|16.99| +## Body ## + +I started out with a 1962 Stratocaster design file created in Alibre by +user protomachinst6 on CNCzone. + +http://www.cnczone.com/forums/musical-instrument-design-and-construction/17659-cnc-32.html + +I originally hoped that I would be able to use FreeCAD to modify this design, +but the STEP import process seemed to lose the ability to keep the various +sub-assemblies oriented correctly relative to each other. Since Alibre has +been replaced by Geomagic Design, I pulled down a 15-day trial version of +that package to one of the Windows machines in the house, and (not +surprisingly)it was able to read the file just fine. + +Another interesting STEP file of the body from a 1962 strat drawn by Marc +Erasmus is available on [GrabCAD](https://grabcad.com/library/62-strat-asm) +and it appears at least one person has actually built a guitar using these +files. + +To build the guitar body I want, the existing body design file needs to be +modified to eliminate the tremolo cut-out and rear cavity, to add screw holes +for the hard-tail bridge, and to shift the electronics cavity from being +front-open to being rear-accessible with the front just having 3 holes for +the volume and tone control shafts and the slot and mounting screw holes +needed for the pickup selector switch. + ## Wiring ## A standard strat has a volume control, 2 tone controls, and a 5-way pickup diff --git a/rockets/airframes/MehGaNuke/index.mdwn b/rockets/airframes/MehGaNuke/index.mdwn new file mode 100644 index 0000000..5a14e06 --- /dev/null +++ b/rockets/airframes/MehGaNuke/index.mdwn @@ -0,0 +1,123 @@ +# Meh-ga Nuke + +## Motivation + +Years ago, Bdale flew some [Woot](http://woot.com) screaming flying monkey dolls +in his [L3 certification airframe](http://gag.com/rockets/airframes/Goblin10/), +leading to some seriously amusing [videos](https://www.youtube.com/watch?v=q7C-sqdSo8M). + +Unfortunately, that airframe was one of many lost in the +[Black Forest Fire](http://www.gag.com/blackforestfire.html). + +At a conference late in 2014, one of the founders of Woot approached Bdale to talk +about the possibility of another sponsored rocket project for his new venture, +[A Mediocre Corporation](https://mediocre.com/) and its flagship site +[meh](http://meh.com). + +Bdale had already started thinking about building another "big-ass rocket" ... + +After giving it some serious thought, the goal became building something bigger +than anything Bdale had built and flown before, but that would fit in with the +"mediocre" theme somehow. Most rocket folks start out flying "three fins and a nose +cone", so doing a simple rocket of that style seemed like a good starting +point. The coolest such rocket clan Garbee has ever built was undoubtedly +[Robert's first high-power airframe](http://gag.com/rockets/airframes/LilNuke/), +a [LOC Precision](http://shop.locprecision.com/) +[Lil' Nuke](http://shop.locprecision.com/product.sc?productId=114&categoryId=12) +kit. + +So .. how about a stupidly-large upscale of the LOC Lil' Nuke! A meh-ga nuke! + +## Design Details + +After a bunch of playing around in [OpenRocket](http://openrocket.sourceforge.net/), +and considering the limits of the CNC equipment at hand, an airframe diameter of +approximately 12 inches was chosen. We can fly high on 6-inch research motors +(first flight planned to be on a James Russell research red-flame "O" motor), and +fly low and super crowd-pleasing on fast-burning M motors like the +[CTI Pro98 M3400WT](http://pro38.com/products/pro98/motor.php) in a suitable adapter. + +To achieve sufficient stability on an O motor, the nose needs to be pretty +heavy. Simulation suggests that turning the nose out of solid pine would work +out just about perfectly. + +Because such a heavy nose cone will put significant compression load on the rest +of the airframe, we'll build internal structure to carry that load rather than +depending on the airframe material itself. Some quick back of the envelope +calculations suggest that 3 ribs made of cheap, common 1x2 pine lumber should +more than suffice. + +The fins will be fabricated from nominal 1/2 inch birch plywood, rounded, +vacuum-bagged with one layer of carbon fiber for stiffness and one layer of +fiberglass for surface preservation and strength. They will insert into fin +grooves cut in the forward and aft fin rings and interlocked with two +intermediate rings. All fin to ring joints will be augmented with chopped +fiber and/or glass fabric scraps. Once the fin can is fully assembled, an +extra layer of fin to fin glass across the airframe will be installed to +help keep the fin can together during landings. + +The airframe will be constructed from 12-inch concrete form tubing with the +inner and outer layers peeled, wrapped with two layers of 6oz fiberglass. A +section of airframe tubing wrapped with one glass layer will be slit and +closed down to form a coupler so the main airframe can be built in two pieces +to ease transportation and flight prep. + +Recovery will involve a 3-foot drogue parachute deployed by blowing the nose +cone off at apogee, and an ARRD will be used to release a 28-foot main chute +from a deployment bag. For high flights, a reasonable main deploy height for +traditional "dual deploy" recovery will be chosen. For lower flights, the +main will be deployed just long enough after apogee to permit the drogue to +re-orient the airframe, approximating the "main out at apogee" experience. + +A side-access electronics bay will be constructed in the valley between two +fins near the leading edge of the fins. Electronics will consist of one +each Altus Metrum [TeleMega](http://altusmetrum.org/TeleMega) and +[TeleMetrum](http://altusmetrum.org/TeleMetrum) boards. The TeleMega is +overkill, but I'm curious to see what the airframe rotation rates are like +in flight, and the gyros will capture that. Each will use a single 850mAh +LiPo battery, and rotary switches mounted in the airframe for on/off. Two +charge cups will be mounted on the forward ring of the fin can for apogee +deployment, and an ARRD will be mounted on the other side of the same ring +for main deployment. + +The main airframe tube will contain ribs and additional structure to carry +the load induced by the nose cone, and to direct apogee deployment gasses +around the main parachute deployment bag. + +Because the kinetic energy at ground impact even under the large main will +be fairly high, the ring at the aft end of the airframe will be doubled +to 1.5 inches thick for extra strength. + +The airframe will be set up with 1515-sized rail buttons, and use of +Terry Lee's launch trailer with 20 foot rail is assumed to ensure stability +for all flights. + +## Construction Log + +2014.04.16 +Purchased 12 feet of 12 inch concrete casting tube from White Cap, they cut +it for me into pieces approximately 8.5 and 3.5 feet long. + +2014.04.18 +Peeled the tubes inside and out, resulting cardboard measures 12" ID, +and 12.25" OD. Cut two centering rings from scrap 1/2" OSB to allow use of +on-hand 3/4" copper water pipe as an axle during glassing operations. I +ended up cutting the longer piece of airframe tubing to ease the glassing +process, such that I can "wrap normally". + +2014.04.19 +Realized I only have enough glass to do one layer on the coupler. Placed +order for a full roll of 60" width 6oz E-glass. Used West Systems 105 +resin and 209 extra-slow hardener mixed in 3-pump batches to bond one layer +of glass and peel-ply to the coupler tube. Took either 15 or 18 pumps total, +the cardboard tube is much "thirstier" than the PML phenolic tubing I've +glassed for previous projects. Given how much cheaper the concrete casting +tube is, this is fine, I'll just need to pay attention to my epoxy stock and +order more if needed! + +2014.04.20 +Peeled the peel-ply on the coupler. Looks adequate for use as a coupler, +but there are several spots where more epoxy would have made me happier. Will +compensate when wrapping the airframe tubes. Given how "thirsty" the cardboard +is, I think the trick will just be to paint the tube with a thick layer of epoxy +before starting to apply the glass, then be generous when wetting each layer. -- 2.30.2