Entry level HPR

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<lecture mode on, can't help it, may be retired but am always a teacher>
Some 1:1 epoxies do have fillers, but most epoxies are 100% solids when cured, by virtue of the many curatives available of different equivalent weights. It's not hard to select one or to mix a couple together to get that ratio. To cure "standard" DGEBA epoxy (very thick; Dow DER-331 or Shell's EPON-828) with diethylene triamine takes a ratio of roughly 100(epoxy):10; with diethylamino propylamine it's 100:7; 4,4' methylene dianiline it's 100:28.5; and Versamid 140 is 1:1 but very slow and thick (or 100:50 can be used at elevated temperatures). Half Versamid and half DETA, for example, would give a thinner mix that cures more slowly, and at a 100:30 ratio.

Laminating (thin) epoxies have what are called 'reactive diluents', very thin liquids with the same epoxy groups, so they react with the curative too. The diluents aren't used by themselves because they're too thin, often react too fast and heat too much, or shrink too much.

Lord no, I don't have all that information in my head...I've got an old 'Epoxy Resins' by Lee and Neville right at hand. A third of the battle in learning is knowing where to find the information you need. (A third is formulating the right questions, the rest is your knowledge.)

Quiz on Friday :)
<lecture mode off>

Best -- Terry
Would you recommend this as a reference work; or would you recommend a different text?

I'm slowly gathering collegiate texts which cover broad portions of our hobby, but epoxies & composites aren't yet on the shelf.
 
Would you recommend this as a reference work; or would you recommend a different text?

I'm slowly gathering collegiate texts which cover broad portions of our hobby, but epoxies & composites aren't yet on the shelf.

Lee and Neville have several books, the one I have is about 3/4" thick. There's a much more detailed edition in the uni library, about 2" thick, and newer.

Rather than buying a textbook you might see about (free) interlibrary loans, or visit a nearby uni library. That way you can look through a book and see if it's if it's a keeper or a nope-nope-nope at no charge. Lee and Neville works are pretty much uni level and very upper-level chemistry-oriented. In fact, I can't use much of the info in the book I've got--some is over my head--but the little I can use is quite valuable. It was worth the $1 I paid for it when they were getting rid of old books at the uni library.

Best -- Terry
 
Lee and Neville have several books, the one I have is about 3/4" thick. There's a much more detailed edition in the uni library, about 2" thick, and newer.

Rather than buying a textbook you might see about (free) interlibrary loans, or visit a nearby uni library. That way you can look through a book and see if it's if it's a keeper or a nope-nope-nope at no charge. Lee and Neville works are pretty much uni level and very upper-level chemistry-oriented. In fact, I can't use much of the info in the book I've got--some is over my head--but the little I can use is quite valuable. It was worth the $1 I paid for it when they were getting rid of old books at the uni library.

Best -- Terry

Big portions of Sutton are over my head as well, but the diagrams and tables are worth the shelf space :). Thanks for the sidebar!
 
I used a LOC kit like many others and chose the LOC graduator (2.56" diameter airframe) and posted a level 1 build thread on this forum to help others since everyone here helped me, pass it forward. :) I will say look into customizing your shock cord to be kevlar and not any of the stretchy shock cords-it is one upgrade I always make sure to do if it doesn't already come with kevlar or flat (non stretchy nylon) already.

I agree, low and slow is waaaaay better the first time for your level 1. A friend in my club once told me, I would rather see the flight than watch it disappear into the clouds the first time. I did a ~3000ft flight, saw most of it, it was a sunset launch, and recovered it ready to fly again. I couldn't have asked for a better Level 1 attempt.

I learned a lot since then and am slowly putting a level 2 build together (also posted on this forum) and taking my time learning new techniques. The go pro mount would be neat but you can always add it to the shock cord if your willing to send a nice Go pro HD up in the air...I have a go pro but would purchase a keychain camera or fashion something from an old pc camera - cheaper than losing or destroying a go pro.

I used a 29mm H97 (29/240 AT case) and it left a nice black chimney stack to follow...pick your propellant from a manufacturer and then get the case size you'll need or use single use. I use AT only because I used it in the 90's...there are many others. I also recommend learning the propellant "behaviors" (warp9 yikes!) and visual effects as well (thrust/impulse).

Oh yeah and if you aren't already, you might want to start using a free rocket simulation/cad program-there are a few out there for free (open rocket, 30 day free rocksim)
 
I built a all fiberglass rocket with 5 minute Gorilla Epoxy (Bought at Walmart) to prove a point that if used correctly it will hold up to a Mach+ aggressive flight. All parts were washed with Dawn dish soap and water. Bonding surfaces were wiped with Acetone and sanded with 80 grit sand paper before bonding. I then proceeded to fly it on a Mach busting flight to 8,000+ft. It flew perfectly except for the main chute tangling and it landing hard. No damage. It's flow many more aggressive flights over the years.

Enjoy,
 
I used a LOC kit like many others and chose the LOC graduator (2.56" diameter airframe) and posted a level 1 build thread on this forum to help others since everyone here helped me, pass it forward. :) I will say look into customizing your shock cord to be kevlar and not any of the stretchy shock cords-it is one upgrade I always make sure to do if it doesn't already come with kevlar or flat (non stretchy nylon) already.

I agree, low and slow is waaaaay better the first time for your level 1. A friend in my club once told me, I would rather see the flight than watch it disappear into the clouds the first time. I did a ~3000ft flight, saw most of it, it was a sunset launch, and recovered it ready to fly again. I couldn't have asked for a better Level 1 attempt.

I learned a lot since then and am slowly putting a level 2 build together (also posted on this forum) and taking my time learning new techniques. The go pro mount would be neat but you can always add it to the shock cord if your willing to send a nice Go pro HD up in the air...I have a go pro but would purchase a keychain camera or fashion something from an old pc camera - cheaper than losing or destroying a go pro.

I used a 29mm H97 (29/240 AT case) and it left a nice black chimney stack to follow...pick your propellant from a manufacturer and then get the case size you'll need or use single use. I use AT only because I used it in the 90's...there are many others. I also recommend learning the propellant "behaviors" (warp9 yikes!) and visual effects as well (thrust/impulse).

Oh yeah and if you aren't already, you might want to start using a free rocket simulation/cad program-there are a few out there for free (open rocket, 30 day free rocksim)


I also did my Level 1 with a LOC Graduator. I added a longer motor mount and extra centering ring. Also a Payload Section. I flew it on an Aerotech H128. I used Aeropoxy glue. Successful L1 back in 2002. The same rocket and motor should be a good choice today as well.
 
I would focus on one step at a time. Plan, buy, build, test, cert attempt L1 then see where you are at for L2.

I used a Estes PS2 Argent built with: TB2 wood glue, fixit epoxy, 5min epoxy, kevlar shock cord to elastic, nomex pad, laundry shelf, 3d printed rail guides, 36" TFR chute, JLCR set for 300'.

I was able to test fly the rocket on a G40 DMS. Then fly on a AT H115 DM, drilled the delay to 10s and enjoyed the show.

If I were to do it over I would have picked out a 2.6-3" cardboard kit, 1/4" kevlar tape shock cord at least 2 times the length of the rocket with a loop 16" down for the main, 38mm mmt then adapt down to a 29mm for the AT LMS G79 test flight then see what 38mm L1 motors would work well for field size and weather conditions.

I use Thrust curve on my phone for motor selection and altitude/velocity predictions.

~John
 
Likely your L1 will Be well used by the time you go for L2! You can be more L1 motors the same day you cert!

Many manufacturers are small business and will help you any way you want.
For great instructions Mac Performance is awesome, many other give great service as well.
Binder Design, Madcow, LOC, wildman etc
 
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