EX Talk - Experimental Rocketry

Poor HTPB cure

feeds@yuku.com (Neway) — Wed, 04 Nov 2009 13:26:11 GMT

Hello! Finally I recovered some R45 HTLO from the university and I started some cure experiments with a MDI curing agent.
I tried to make a 0,08 curing ratio as descrived in "How to make amateur rockets" of CP technologies.
5 grams of R45 and 0,4 grams of MDI measured with a 1/100 gram scale
After 24 hours the HTPB is very sticky.
What I have to do? A bit more curative?

Thanks
Adriano

Metal Mesh Size

feeds@yuku.com (gregmuri) — Wed, 04 Nov 2009 13:21:01 GMT

Something I have never had a real grasp on is what, if any, impact the particle size of metals in a formula have on its burn characteristics.

What got me thinking about this is a couple things. First, I have used 325 and 400 mesh Al and Mg basically interchangably with no noticable difference in performance. Second, I don't think I have more than one single formula in my library that calls for metals with a particle size smaller than 400.

A good example of this would...

HTPB needed

feeds@yuku.com (Neway) — Sat, 31 Oct 2009 05:39:37 GMT

Hello, living in italy is difficult to get some R45 or R20 and the curative because experimental is not common in europe, so vendors doesn't stock binders. My request is this:
Can somebody be so kind to ship me a gallon of R45 or R20 plus curative and possibly with some DOA? I will return the favor.

Good weekend
Thanks
Adriano

Sparky test

feeds@yuku.com (motorman48) — Sun, 25 Oct 2009 22:27:22 GMT

http://picasaweb.google.com/kenh12355/SparkyMotorTest#5396700097483285986

38mm, 12" propellant. Going for that old Silver Streak look. Yes it was in the evning around 7PM.

Ken

L/D ratio

feeds@yuku.com (rocketsaway01) — Fri, 23 Oct 2009 09:45:42 GMT

Here are 2 BS sims. Both have almost same int and max Kn. First one has an L/D ratio of 1.91, but has a more progressive profile.
Second one has more flatter profile, closer to neutral, but has L/D ratio of 1.74. My understanding is to keep ratios close to 2.
Which one would you use?

blue is thrust.

Single Use 'O' Motor

feeds@yuku.com (Col J Harris) — Wed, 21 Oct 2009 14:08:36 GMT

Just throwing an idea out here.

Would anyone be interested in single-use 4.5" 'O' motors??

Curative Storage

feeds@yuku.com (KN) — Wed, 21 Oct 2009 12:39:39 GMT

Wondering what you guys are doing to keep moisture out of your curative. I live in Houston, Texas (Humid City) and I do keep my E744 in doors in a Mason jar. I mix outside in my shop and after using for several mix sessions the curative starts to get cloudy and solids form at the top edges. It then becomes a cloudy greenish color instead of its normal clear yellowish tint. I have played around with vacuum degassing it and after a few sample tests...

Magnesium - How to dispose??

feeds@yuku.com (gregmuri) — Mon, 19 Oct 2009 08:57:22 GMT

I have a pound container of 1250 mesh Mg that I would rather not keep around. Any suggestions on a safe way to dispose of this stuff?

Greg

Who says 29mm's don't make sparks?

feeds@yuku.com (StreuB1) — Wed, 14 Oct 2009 20:24:02 GMT

Vacuum pumps

feeds@yuku.com (JimmyL) — Tue, 13 Oct 2009 14:42:31 GMT

Has anyone tried any of the cheap vacuum pumps that are showing up on E-Bay? Some of them are 2.5cfm with a vacuum down to 29.75 all this for less than $100 including shipping. Just wondering. Thanks JimmyL

An "O" ring question

feeds@yuku.com (rocket999) — Sun, 11 Oct 2009 17:19:29 GMT

I had a question about o ring sizing. I am contemplating building a micro hybrid and I wasn't sure what size o ring to order. The inside diameter of the tube is 0.8 inches. The o ring is going to be 1/16 in thick. Should the OD of the o ring be the same as the ID of the motor tube?

Sam

Looking for a copy of Australian Experimental Strand Burner manual

feeds@yuku.com (EdBrown) — Sun, 11 Oct 2009 12:12:07 GMT

I am looking for a copy of the Australian Experimental Strand Burner manual. If anyone has one for sale, please contact me at ed.brown@bresnan.net.
Thanks,
Ed Brown

DOA or IDP

feeds@yuku.com (KN) — Thu, 08 Oct 2009 07:11:47 GMT

Just wondering where you guys are buying your plasticizers from? RCS and Aerocon is kind of pricey with shipping and I don't want to order from Firefox if I don't have to. Looking for a gallon or two.
What about magnesium, say -200 mesh? Getting a little hard to find. Any Help?
Thanks.
Dave

Balls??

feeds@yuku.com (JDcluster) — Sun, 04 Oct 2009 17:46:44 GMT

Anyone here anything lately?
It's been too quiet around here.

JD

What gloves?

feeds@yuku.com (Neway) — Fri, 02 Oct 2009 13:43:01 GMT

What gloves best protect from polyurethane, HTPB and other chemicals we use for experimental propellant?
Latex? Nitril?

Thanks a lot!

Possible EX Mixer

feeds@yuku.com (Shocker85) — Tue, 29 Sep 2009 11:59:40 GMT

Stumbled across this older Hobart 10QT mixer on ebay: http://tinyurl.com/ye6u9me

Located in central Illinois and seller provides phone number for questions.

Maybe a good fit for a TQC EX'er.

Lance.

Everclear Isp?

feeds@yuku.com (StreuB1) — Mon, 28 Sep 2009 20:52:04 GMT

Im wanting to sim a certain motor with the everclear propellant thats listed gary rosenfields site. It lists the a and n numbers but doesnt list an Isp for it. Does anyone have any additional information about this propellant??

Aerotech delay casings

feeds@yuku.com (CarolRyan) — Sat, 26 Sep 2009 18:55:52 GMT

What type of clear plastic material does Aerotech use for their 38mm delay grains?

Doc

forward bulkhead thermal insulation.

feeds@yuku.com (EKosoof) — Sat, 26 Sep 2009 14:09:17 GMT

What steps does one need to take to insulate the forward bulkhead on a 75mm size motor, when the propellant has a high metals content, 10 - 15%. G10 disc, layer of EPDM? Phenolic is hard to find in NZ.

Ethan

Alternative binder

feeds@yuku.com (Neway) — Sat, 26 Sep 2009 12:35:54 GMT

Hello! I have a small problem. I'm not able to get HTPB or PBAN here in europe, so I need an alternative binder for my APCP.
I can get polyuretane or epoxy resin. Which is the best?

Thanks a lot
Bye
Adriano