# Aerospace/Interesting Stuff (Bookmarks)

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#### ResearchWorm

##### Well-Known Member
I apologize for dumping an edited bookmarks page on the forum, but I found an awful lot of material today. Some of this pertains to aerodynamics (transonics anyone?). I figured I would share my results. Most of these are aerospace related links.

Harm none,

ResearchWorm.

<dl class=first>
<dd><a href="https://bofh.ntk.net/Bastard.html">THE BASTARD OPERATOR FROM HELL OFFICIAL ARCHIVE</a></dd>
<dd><a href="https://www.theregister.co.uk/2004/05/07/caltech_slow_neutrons/"> Boffins slow neutrons to 15mph | The Register </a></dd>
<dd><a href="https://finance.yahoo.com/q?s=scox">SCOX: Summary for SCO GROUP INC - Yahoo! Finance</a></dd>
<dd><a href="https://www.theregister.co.uk/"> Headlines | The Register </a></dd>
<dd><a href="https://draco.acs.uci.edu/rbfaq/FAQ/index.html">https://draco.acs.uci.edu/rbfaq/FAQ/index.html</a></dd>
<dd><a href="https://www.theregister.co.uk/2004/05/26/bolly_mug_launch/"> My job went to India... | The Register </a></dd>
<dd><a href="https://news.bbc.co.uk/1/hi/health/3104093.stm"> BBC NEWS | Health | Tight ties could damage eyesight </a></dd>
<dd><a href="https://www.pbs.org/cringely/archive/">PBS | I, Cringely Archives</a></dd>
<dd><a href="https://www.theinquirer.net/"> Welcome to the Inquirer </a></dd>
<dd><a href="https://www.darwinawards.com/darwin/">Official Darwin Awards</a></dd>
<dd><a href="https://www.pacificwrecks.com/reviews/thirty.html">Book Review: No Surrender</a></dd>
<dd><a href="https://www.theinquirer.net/?article=17099"> DVD pirate tries to sell wares to Trading Standards </a></dd>
<dd><a href="https://news.bbc.co.uk/1/hi/world/africa/3887493.stm"> BBC NEWS | World | Africa | Turning the tables on Nigeria's e-mail conmen </a></dd>
<dd><a href="https://www.bbc.co.uk/wiltshire/features/polyplay.shtml">BBC - Wiltshire - Features - Fancy a game, comrade?</a></dd>
<dd><a href="https://www.theregister.co.uk/2004/07/14/your_datas_is_at_risk/"> Your data is at risk - from everything | The Register </a></dd>
<dd><a href="https://neil.fraser.name/hardware/3d-mouse/">Neil Fraser: Hardware: 3D Mouse</a></dd>
<dd><a href="https://www.theregister.co.uk/2004/07/20/musical_preference_survey/"> Developers play air guitar to Megadeth | The Register </a></dd>
<dd><a href="https://www.evergreenaviation.com/supertanker/index.html">Evergreen Supertanker -747 waterbomber</a></dd>
<dd><a href="https://news.bbc.co.uk/2/hi/americas/3915659.stm"> BBC NEWS | Americas | US army food... just add urine </a></dd>
<dd><a href="https://www.eviloverlord.co.uk/humour101/humour101.html">Phrases you wish you could say at work</a></dd>
<dd><a href="https://www.thalia.org/lists.html">The thalia.org Evil Overlord Lists Department</a></dd>
<dd><a href="https://www.linuxdevices.com/news/NS2844504302.html">Linux computer squishes into CompactFlash card</a></dd>
<dd><a href="https://story.news.yahoo.com/news?tmpl=story&amp;ncid=751&amp;e=1&amp;u=/nm/20040808/hl_nm/environment_britain_prozac_dc"> Yahoo! News - Report: Prozac Found in Britain's Drinking Water </a></dd>
<dd><a href="https://www.batbox.org/nslu2-linux.html">Linux on the NSLU2</a></dd>
<dd><a href="https://www.lilliputmodel.com/alabarda/biblioteca/biblio4.htm">A.C.M.H. Alabarda</a></dd>
<dd><a href="https://physicsweb.org/article/news/8/8/9">PhysicsWeb - Glass breakthrough</a></dd>
<dd><a href="https://dubiousquality.blogspot.com/">Dubious Quality</a></dd>
<dd><a href="https://www.nist.gov/public_affairs/releases/miniclock.htm">NIST Unveils Chip-Scale Atomic Clock</a></dd>
<dd><a href="https://www.rolltronics.com/">Rolltronics Home</a></dd>
<dd><a href="https://www.fcctests.com/sample/default.asp">Tech Services FCC Tests</a></dd>
<dd><a href="https://www.fcctests.com/">Online practice tests for FCC Licenses - MROL, GROL, GMDSS Operator, GMDSS Maintainer, and Radar Endorsement</a></dd>
<dd><a href="https://ntrs.nasa.gov/"> NTRS: NASA Technical Reports Server </a></dd>
<dd><a href="https://rocketworkbench.sourceforge.net/equil.phtml">Cpropep-Web</a></dd>
<dd><a href="https://www.discovercircuits.com/list.htm">Discover Circuits, a collection of 8000+Â_ free electronic circuits schematics to solve design problems </a></dd>
<dd><a href="https://zapatopi.net/afdb.html">Aluminum Foil Deflector Beanie</a></dd>
<dd><a href="https://www.fs.fed.us/gpnf/volcanocams/msh/">Mount St. Helens VolcanoCam - Mount St. Helens National Volcanic Monument</a></dd>
<dd><a href="https://www.techbooksforfree.com/">Free Programming and Computer Science Books</a></dd>
<dd><a href="https://www.adl.gatech.edu/classes/index.html">Aerospace Design Library: Course Notes</a></dd>
<dd><a href="https://www.loc.gov/rr/scitech/tracer-bullets/aerodynamicstb.html">Aerodynamics (Mechanics of Flight) (Science Tracer Bullet - Science Reference Services, Library of Congress) </a></dd>
<dd><a href="https://www.loc.gov/rr/scitech/tracer-bullets/spacesciencetb.html">Space Science Projects (Science Tracer Bullet - Science Reference Services, Library of Congress)</a></dd>
<dd><a href="https://www.vs.afrl.af.mil/">AFRL's Space Vehicles Directorate</a></dd>
<dd><a href="https://www.aviationnow.com/content/reference/sourcebook/sourcebook.htm">2004 Source Book</a></dd>
<dd><a href="https://nix.nasa.gov/">NASA Image eXchange (NIX) - Home</a></dd>
<dd><a href="https://trisonline.bts.gov/sundev/search.cfm">USDOT:BTS:NTL:TRIS Online</a></dd>
<dd><a href="https://www.dfrc.nasa.gov/Research/">Dryden Flight Reseach Center: Flight Research Projects</a></dd>
<dd><a href="https://standards.nasa.gov/">NASA Technical Standards Program</a></dd>
<dd><a href="https://dodssp.daps.dla.mil/">DODSSP Web Site Gateway</a></dd>
<dd><a href="https://www.jpl.nasa.gov/technology/">JPL NASA Technology</a></dd>
<dd><a href="https://neds.daps.dla.mil/">Navy Electronic Directives System</a></dd>
<dd><a href="https://www.isunet.edu/">International Space University</a></dd>
<dd><a href="https://www.aerospaceweb.org/">Aerospaceweb.org | Reference for Aviation, Space, Design, and Engineering</a></dd>
</dl>

#### DynaSoar

##### Well-Known Member
You could also submit them to the Link section on EMRR.

#### hokkyokusei

##### Well-Known Member
Originally posted by ResearchWorm
Most of these are aerospace related links.
Are you sure?

#### hokkyokusei

##### Well-Known Member
Originally posted by DynaSoar
You could also submit them to the Link section on EMRR.
After the recent fuss about bad language on EMRR, I'm not sure they would want some of those links.

#### ResearchWorm

##### Well-Known Member
</dl>
<p> Electronic Circuits </p>
This is mostly circuit archives. The one that I was really impressed with is the Heathkit archive. If you're an antique radio geek, you'll like the Vintage Circuits archive.

<dd><a href="https://www.uoguelph.ca/~antoon/circ/archive/archive.html">Circuit Archive, Archived Circuits</a></dd>
<dd><a href="https://www.commlinx.com.au/schematics.htm">Electronic circuit schematics</a></dd>
<dd><a href="https://www.ee.oulu.fi/~arik/schematics.html">Electronic Circuits</a></dd>
<dd><a href="https://www.geocities.com/iecmaster/elec_cir.html">IEC - Circuits Archive</a></dd>
<dd><a href="https://www.4qdtec.com/">4QD-TEC: Electronics Circuits Reference Archive Index</a></dd>
<dd><a href="https://www.ee.washington.edu/circuit_archive/">Circuits Archive - UWEE</a></dd>
<dd><a href="https://www.solorb.com/elect/">FC's Electronic Circuits</a></dd>
<dd><a href="https://www.discovercircuits.com/">Discover Circuits- home page, a collection of 8000+Â_ free electronic circuits schematics to solve design problems </a></dd>
<dd><a href="https://www.heathkit-museum.com/ListArchive/msg01284.html">Heathkit Virtual Museum | Heathkit Listserv Archives</a></dd>
<dd><a href="https://www.circuitarchive.co.uk/">CircuitArchive - schematics and circuit diagrams from 1920's to 2004</a></dd>
<dd><a href="https://www.ee.ualberta.ca/html/cookbook.html">The Electronic Cookbook Archive</a></dd>
<dd><a href="https://www.hut.fi/Misc/Electronics/circuits/">Tomi Engdahl's Electronics Pages</a></dd>
<dd><a href="https://64.233.161.104/search?q=cache:YiQXYnicvQEJ:www.amasci.com/amateur/elehob.html+circuit+archive&amp;hl=en">ELECTRONICS HOBBYIST</a></dd>

<dd><a href="https://www.ukrocketman.com/rocketry/avionics.shtml">UK Rocketman - Avionics</a></dd>
<dd><a href="https://www.aprs.net/vm/DOS/INDEX.HTM">Automatic Packet/Position Reporting System (APRS)</a></dd>
<dd><a href="https://www.aviationtoday.com/">Aviation Today - First Choice of Aviation Insiders Worldwide</a></dd>

<p>Embedded/Single Board Computers (some rocket sized)</P>
Somewhere I ran across a really good BASIC52 microcrontroller website and didn't bookmark it, and I do not remember where I found it. Check out the Circuit Cellar magzine website for lots of good stuff (BASIC52 projects as well). www.circuitcellar.com

<dd><a href="https://www.nationmaster.com/encyclopedia/List-of-software-engineering-topics">Encyclopedia: List of software engineering topics </a></dd>
<dd><a href="https://www.discovercircuits.com/list.htm">Discover Circuits, a collection of 8000+Â_ free electronic circuits schematics to solve design problems </a></dd>
<dd><a href="https://www.applieddata.net/defaultSBC.asp">Single Board Computers- SBC with XScale and RISC CPU</a></dd>
<dd><a href="https://www.phytec.com/sbc/sbc16.htm">PHYTEC 16-Bit Single Board Computers</a></dd>
<dd><a href="https://www.portwell.com/robo-503.htm">Portwell Embedded Board: ROBO-503</a></dd>
<dd><a href="https://www.portwell.com/robo-603.htm">Portwell Embedded Board: ROBO-603</a></dd>
<dd><a href="https://www.atmel.com/dyn/products/product_card.asp?part_id=2983">Atmel Corporation - Product Card</a></dd>
<dd><a href="https://www.quasarelectronics.com/abc_products.htm">Atmel AVR Basic Controller Development Boards</a></dd>
<dd><a href="https://www.pjrc.com/tech/8051/">Paul's Free 8051 Tools, Code and Projects</a></dd>
<dd><a href="https://www.axman.com/Pages/neuprod8main.html">Axiom Manufacturing</a></dd>
<dd><a href="https://www.mecanique.co.uk/products/dev-boards/">Development Boards</a></dd>
<dd><a href="https://www.futurlec.com/CP68HC908DevBrd.shtml">68HC908 Development Board</a></dd>
<dd><a href="https://www.beyondlogic.org/usb/usbhard.htm">USB1.1 Integrated Circuits and Development Boards</a></dd>
</dl>

Harm none,

ResearchWorm

#### ResearchWorm

##### Well-Known Member
Yet another flurry of links. These are all Basic Electronics and Electronics related stuff. One of the first couple of ones is aimed at teachers who want to teach electronics in a K-12 educational environment.

<dl>
<dd><a href="https://scitec.uwichill.edu.bb/cmp/online/online.htm">DEPARTMENT LECTURE COURSES ONLINE</a></dd>
<dd><a href="https://directory.thestar.com.my/cat.asp?/Science/Technology/Electronics/Tutorials/">The Star Online Directory - Tutorials</a></dd>
<dd><a href="https://scitec.uwichill.edu.bb/cmp/online/online.htm">DEPARTMENT LECTURE COURSES ONLINE</a></dd>
<dd><a href="https://www.ibiblio.org/obp/electricCircuits/">Lessons In Electric Circuits &lt;AWESOME!&gt;</a></dd>
<dd><a href="https://members.tripod.com/michaelgellis/tutorial.html">On-Line Tutorials &lt;Lotsa links elsewhere&gt;</a></dd>
<dd><a href="https://www.rfcafe.com/references/education_home.htm">RF Cafe - Online Education -&lt;Radio stuff&gt;</a></dd>
<dd><a href="https://users.pandora.be/educypedia/electronics/digital.htm">The educational encyclopedia, course material: digital logic</a></dd>
<dd><a href="https://www.eta-i.org/">ETA International &lt;Professional Stuff&gt;</a></dd>
</dl>

It'd be nice to get some feedback as to wether or not this is helpful, or if there was something that I could find that would be helpful. There's a lot of people checking out this thread, but nobody's commenting.

I've already recieved a request for a basic mold making thread, and I'll be working on that this evening. Hopefully I should have one put together by Friday.

Harm none,

ReseachWorm

#### ResearchWorm

##### Well-Known Member
Sorry folks, I had a moderately extensive (20+ links) post to resources about scramjets, ramjets, and pulse detonation engines that I was working on (since the X-43A is such a cool piece of technology) , but my browser crashed. So here's the ones that I actually wrote down. Yes, I know it's a shock, I actually do know how to use pencil and paper. My handwriting is almost legible even to me.

https://yarchive.net/space/launchers/scramjets.html Some comically outdated stuff from a newsgroup. Didn't poke around too much though.
https://www.pr.afrl.af.mil/history_wpafb.html <- Nice history page for the USAF's engine research folks.
https://www.aerospaceweb.org/design/waverider/design.shtml <-Aerospace Engineering Student Project webpage on waveriders/hypersonic planforms. VERY detailed.
https://www.mie.utoronto.ca/labs/mfl/propulsion/lectures/lecture4/ < an intro for Engineering Students.
https://www.onera.fr/conferences/ramjet-scramjet-pde/ <-Cool page about the history, current uses, and odd critters (Air Breathing Solid Fuel Ramjets anyone?)
https://www.aviation-history.com/index-engine.htm
https://arjournals.annualreviews.org/doi/abs/10.1146/annurev.fl.28.010196.001543 <- Geek PDF!
https://hypersonic2002.aaaf.asso.fr/papers/17_5145.pdf <- Pdf of a technical paper on Hypersonics. Pretty good read.
https://www.floridatoday.com/NEWSROOM/spacestoryN1115PLANE.htm
https://www.aoe.vt.edu/~mason/Mason_f/ConfigAeroHypersonics.pdf < Hypersonic Aerodynamics.. Dated, but interesting.

I apologize in advance for the small number of links, but I didn't feel like digging through to find them all again.

Harm none,

ResearchWorm

#### GL-P

##### Well-Known Member
You said there was some links for the transonic region?

Could you point out the link pls

Thanks!

#### ResearchWorm

##### Well-Known Member
I found a couple of transonic links that I don't think I've put up in this thread before, so here's so more stuff for everyone to browse through..

www.aoe.vt.edu/~mason/Mason_f/AIAA2003-4062.pdf

Wander around the URL on this site, ~mason has an awful lot of stuff to read.

https://www.eevl.ac.uk/engineering/...ion=Class+Browse&browsestart=793&leafdata=765

EEVL is <B>THE</B> Engineering Virtual Library in the UK, and this is one of the best broad topic VL's that I have ever run across. If you cannot find something relating to what you are looking for, you don't know how to look. You might not find exactly what you're looking for here, but you'll find pointers. This is the link to the Transonic Aerodynamics subsection.

Aerade is the aerodynamics/aerospace only VL run by Cranfield University, which is one of the best schools in Europe to attend if you are wanting to pursue a top of the line education in Aerospace. Think MIT mixed with UCLA, but with a class schedule designed by NASA.
A decent percentage of the EDA, Airbus and ESA engineers have either are, or have been trained by, graduates of Cranfield. I highly suggest poking around aerade.

https://aerodyn.org/HighSpeed/highspeed.html

This is a decent nutshell coverage of transonics, at least the page referenced is, but dig deeper into the subpages for the meaty bits of knowledge you really want.

Which reminds me of something.. If you are designing a fin can for a rocket that you know for certain is going to pass or approach the transonic region, don't put a subsonic profile on the fins. I'm going to have to find some resouces on wing/fin profiles for symetrical supersonic and subsonic conditions. More digging!

https://www.aa.nps.navy.mil/~jones/online_tools/ Mostly useless stuff (even the author says so), but the last link on the page is rather interesting. It's a 2-D javascript CFD (computation fluid dynamics) for generalized transonic aerfoils. The author has some really neat papers at: https://www.aa.nps.navy.mil/~jones/publications/ Definely poke around in the sidebar. Lots of useful, or at least, interesting stuff here.

Here's a pool of journals that a friend of mine pointed out to me, and I've been swimming in it for year or so. It is so easy to get lost in this one, and forget what you were looking for. [urll]https://www.doaj.org/home[/url] It's called the Directory of Open Access Journals. And it's roughly, hrm, about 1000 professional journals with their archives.

There's a fairly impressive amount stuff here, so I'll give you guys a break.

Harm none,

ResearchWorm

#### ResearchWorm

##### Well-Known Member
I'm sorry to disappoint folks by not having any new links for you all to browse through today. I am absolutely exhausted, and can barely think straight, let alone type coherently. Reality has intruded to the tune of 25 hrs of overtime in the last four days. I trust no one will mind all to terribly much.

I've got my notes on for composite mold making in my room, and I'll post those tommorrow or Sunday.

Please let me know if there are any topics you want me to find material on, and I'll do my best to process the requests.

I've got to get about a gallon of coffee in me just so I can stay awake for my normal working hours. Thank goodness I can get more than 4 hrs of sleep tonight.

Harm none,

ResearchWorm

#### GL-P

##### Well-Known Member
Wow!!!

ResearchWorm, sorry to ask for bookmarks if you're that tired!!!

Get a good night sleep b4 you try to do a mold thread. You might forget something impt!!!

Awesome job ResearchWorm!!!

#### ResearchWorm

##### Well-Known Member
There are three basic mold construction techniques that are viable for doing hand layup construction of composite structures.

- Male to Female forming

The inside surface finish is critical, and whatever the outside ends up like, we'll tolerate. In industry, this technique is mostly used for smaller internal surfaces for bodies, hulls, dashboards, etc, as well as forming Female molds from a shaped plug. Mold prep is moderately critical, should well done (do it good enough, and then do it again), and you should have a easy way of removing the finished part. I usually use a putty knife and stir sticks.

- Female to Male

The outside surface finish is critical, and whatever the inside finish end's up like, we'll tolerate. Used for large aerodynamic surface sections (bodies, wings, etc) Mold prep is critical (3 "I think it's good enough" passes), and you should have a positive-pressure way of removing the male part.
I prefer putting a water hose adapter the deepest part of the mold, and popping the part out using water pressure. Air doesn't work that well.

- Mandrel Molding

Tubing and tubing like shapes. Mandrel is usually sacrificial one off unless there is a pressing reason for using a reusable one. Mold prep is critical if intending to have a reusable mandrel.

Male to Female: Making the mold.

Making a MF mold is one of the easist procedures. Manufacture a shapped plug that is dimensioned to the part you want to create, and is "mold friendly" with no overhanging surfaces, slots, etc. I personally prefer using three-part MF mold. This is where I've got a heavily waxed backing board supporting the plug (if it's a small plug), and a two piece plug that is held on to the board with bolts. For simple plug forms, using a single piece plug is best The plug construction I like is particle board, Bondo (tm), or plaster. Once you've got plug you're happy with, finaly sanded to 1200 or better grit) coat it with at <b>least</b> three layers of turtle wax. I prefer to use the molten candle-wax technique. Heat up some candle-wax until it melts to 'really runny stage' and then dip (if the plug is small enough) or pour the wax onto the plug. Wait for the wax to harden, remove the obvious excess, fire up the blow-torch, and remelt the wax until you have a nice shiny surface coating. Then do your turtlewax layers. Once everything is prepped, coat the entire surface with your mold-release agent (Poly Vinyl Alcohol [The Green stuff] works best for me), and let dry. If you're using a gelcoat (making a female mold or a colored part), put it on at this point, allow it to get to the proper stage of hardness, and add your fabric and resin or expoxy. If weight/strength is not critical (if making a female mold, etc), don't worry about vacuum packing, just make a solid part (add lumber/foam reinforcements as neccessary).

Female to Male: Using the mold.

A properly fabricated small form Female to Male mold outweighs the resultant part by a factor of at least 10:1, but should be about 30:1 for most small molds, and the larger the part, the smaller the weight ratio gets, but should never go below 10:1 for stuctural and stability reasons. Yes, a 10 kg carbon fibre body should have a mold weighing 200 kgs. The 150 gram leading edges of the Viking XX vertical strut, made out of a single layer of 45/45/90 CF without any finish layers of fibreglass, came out of a 2 peice 5 Kg female mold, and the plug that formed the mold weighed 18 Kg. I think the main body plug for the Viking XX weighed around 200 kg, the molds were heavy enough we needed a forklift to move them, and the finished parts were about 30 kgs total.
FM molds lend themselve to high-strength final finish parts excessively well, since your finish was created by the Male-to-Female molding process, and then cleaned up by final sanding (Wet-Dry 1200 grit or finer), and because it is so incredibly easy to vacuum pack for very light weight parts. You can layer your fabric just about anyway you need to without worrying about finish problems.

Mold prep is pretty much the same as a MF mold, but I don't like to use the molten candle-wax technique.

Plug your water inlet with a ball papertowel and then a layer of cellophane packing tape. 4 coats of Turtle(tm) wax and one coat of PVA or mold release agent.

Put on latex gloves, safety glasses, a long sleeve shirt and a filter mask, its about to get messy.

Put down a layer Gelcoat if you want, but I've always thought that raw fiber (especially carbon) looks neat. First layer of fabric put down should always be a finish coat fabric, such as 1oz, 2oz, or 3oz fine mesh 45/45/90 fibreglass. This stuff is gossamer light before wetting with resin/epoxy, and will conform to the mold surface extremely nicely with very little bubbling when properly done. Make sure you smooth it nicely.Then lay down your outer layer fabrics as scheduled. Wet out each layer as you put it down. It's always a good idea to put a final layer of fibreglass gossamer on top of your final fabric layer, lay out your air-drain lines and batting along the mold flange (Do you remember the backer board for a MF mold? This is why). I like teflon air-lines and the polyester pillow batting you get at the fabric stores cut into strips about 2" wide, overlapped as needed.Put your air-seal putty outside the batting on the flange, and then unfold your seal sheeting. On a big mold, you might need to have additional batting strips in the mold. I use a heavy clear plastic drop-cloth fabric that costs $3 for a room size package. As long as it is <b> not </b> Poly Vinyl Acetate! You want Polyester or PVC plastic. If you want to be a-retentive about it you can buy the coated$2 per sq. foot stuff that is meant to be reused. Once your sheeting is unfolded (you did remember to measure it, right?) start by placing the plastic in the middle of the mold and work your way towards the edges. Once you've got the sheeting placed, start sqeegeeing your fabric layers, but first put a little liquid dishwashing soap (I prefer Dawn or Ivory), trying to remove the excess resin/epoxy from the fabric. If you can dent the plastic into the fabric with medium finger pressure (easiest way to describe: Take your pointer fingernail, and press against the tendons of your wrist until it gets uncomfortable, but not painful. That's the correct pressure). Squeegee the entire mold, and then seal the plastic down to the putty. Start your vacuum pump. Redo your squeegeeing, with just a little more pressure, working from the middle of the mold outwards. Pay particular attention to apparent dry spots as you work, and try to manuveur excess through them. Once youve got everthing squeegeed a second time, put down your tools, stop working, and let the mold sit until its cured (depends on your epoxy cure time). Remove your part carefully. I prefer "floating" it out using slowly increasing water pressure.

Mandrel Molding:

Commonly used for making tube like things. For this, I prefer using a sacrificial foam, around an aluminum or PVC pipe, mandrel with plywood disc ends (we'll get to those later) or a extremely well prepped aluminum pipe machined to the neccessary diameter. Cut your plywood discs to the just a little less than the inside diameter of the final tube minus two times your fabric stack (how thick is the fabric, that's your fabric stack). Drill a hole in each disk that is slightly larger than the diameter of your aluminum or PVC pipe, and in one disk, drill a second hole 1/2 the diameter of the pipe. This is your fill hole. Put your pipe through center holes, and then build a tube using heavy Kraft paper or cardboard that has been waxed on what will be the inside surface of the tube, stapiling the edges to the plywood. Don't worry about neatness. You're just fabbing a container. Stand the assembly up on end over a stand (a couple of bricks?), with 4 " or so of pipe protruding from each end. Mix your two part expanding foam, and pour, pausing to spin the tube every so often. Fill. Wait for the foam to cure. Peel the cardboard, smooth-coat with expanding foam where neccesarry and then sand into shape using a bow-sanding wand. Brushcoat with molten candle-wax, shave using a razor blade until smooth, and proceed as with prepping/using a female mold.

Metal Pipe Mandrel, next message.

Harm none,

ResearchWorm

#### ResearchWorm

##### Well-Known Member
Metal Pipe Mandrels:

Ugh. I prefer not working with these things. The beauty of a sacrifical foam core is that you can chip or dissolve the core away. If a metal mandrel isn't prepped right, you have a carbon reinforced baseball bat. On that note, pay a lot of attention to prep.

If it is a brand new mandrel, alodine prep clean it. This doesn't mean you need to actually treat it with that poisonous stuff, but prep it like you were about to. Take 3200 grit wet/dry sand paper, and polish-sand the surface. You'll want to wear latex gloves for this, since tiny metal particles are a bother. What you are trying to do is get the surface smooth enough that water, when dripped on to the surface, does not bead up, but flows in a sheeting action off to the side. Once you've got that, the fun starts. Rinse the mandrel well, and dry with paper towel. Spray the entire mandrel with silicone lubricant spray, let it dry, and buff polish with paper towel. Do this three times. Wrap the entire length of the mandrel, not just the area you'll be using loosely with waxed paper. Then overwrap the area you'll be using (plus a couple inches at each end) snugly with mylar or PVC film, taping mylar to mylar only as neccesary to hold the mylar on. This should be the thickness of overhead projector film. With a little effort (no grunting, should be no more effort than turning a doorknob), you should be able to slide the mylar and wax paper back and forth along the mandrel. If not, redo it. Paint the mylar with thick PVA or a similar mold release agent Lay up your fabric schedule as per with a female mold, vac-pack if you want a light tube instead of a log. To remove your finished part once it has cured, soak in soapy water about an hour, put one end of the mandrel in a bench vice, and worry the tube loose.

Here's the reasons I dislike the metal mandrel:
1. If it doesn't work, you have to disolve the mandrel or destroy the tube.
2. Prep is a pain in the neck, and a slight mistake means reason 1.
3. Layup is a pain in the neck, and a slight mistake (too much resin or epoxy) means reason 1.

If you're going to use a metal mandrel, mold prep, mold prep, mold prep. When I've had to use a pipe mandrel, I used thinwall aluminum as it can be removed with hydrochloric acid and patience. If I can get away using either the expanding foam sacrifical mandrel or a waxed cardboard tube, I'll those techniques before I attempt a metal mandrel.

Now, if any of you have been asking why one should use PVA as a release agent... Once it is cured, and you add water to it, the green film turns into a slick liquid. So, if your mandrel sticks, and you did actually use PVA, you can soak the mandrel in soapy water for a bit, and it should just slip out.

Oh, and just as a side note:

The tail structure of the AH-66 (?) Comanche helicopter was done using what I think was an sacrificial foam MF pre-preg tape mold, and the body was done using a FM pre-preg tape mold. It's pretty cool when halves of airframes can be moved around by a couple of people.

Hope this helps,

Harm none,

ResearchWorm