Hack Chat Transcript, Part 2

A event log for Amateur Rocketry Hack Chat

It absolutely is rocket surgery

Dan MaloneyDan Maloney 11/30/2022 at 21:120 Comments

Dan Maloney12:48 PM
So what keeps you going then?

prfesser12:48 PM
@kjansky1 sugar is cheap but has its own problems. Tripoli allows homemade motors that use sorbitol, dextrose, or erythritol as the fuel. All three (esp sorbitol) have far lower melting points than sugar, and none of them are terribly expensive. Of course, when you're making literally a ton of propellant grains, cost enters into the project.

Kip Daugirdas12:49 PM
@Dan Maloney it came to a point where it was sunk cost. I had already invested so much of my time and money into the project that there was no turning back.

Dan Maloney12:50 PM
Man, do I know that feeling.

kjansky112:52 PM
Well chemically sugar or regular sucrose and dextrose(glucose erythritol) , sorbitol etc. are very similar chemically. I was thinking something with less hydroxyl or OH groups and a higher H bond fraction might provide better energy in the combustion.

Alex Mi12:52 PM
it's really, really good achievement, textbook flight... awesome

Dan Maloney12:53 PM
So is Black Rocks open to the public for watching launches? Because I live only about a day's drive away...

Kip Daugirdas12:53 PM
@Alex Mi thank you. I hope to have a repeat flight on the next go.

Alex Mi12:54 PM
lots of work - yeah, that's kinda impossible to beat :) . Would you do this the same way the next time? Judging by your extensive experience, I suspect you knew in advance most of how it's going to look like...

Kip Daugirdas12:55 PM
@Dan Maloney yes anyone can go spectate at a Tripoli launch. Most of the launches are held in the summer and fall. Fall being the most popular time because the weather is tolerable.

prfesser12:55 PM
@kjansky1 The limitation for such propellants isn't in the fuel so much as it is the oxidizer. Even at optimum, potassium nitrate propellants don't provide much more than half the specific impulse of typical APCP.

Alex Mi12:55 PM
but, anyway - 3 years seems like not a whole lot of time for this great results. Grains, machining and video editing... spectacular

Kip Daugirdas12:57 PM
@Alex Mi I probably would not change much. The only things I would look at changing would be the protective coatings on the leading edges of the second stage fins. Mach 4+ flight leads to very high stagnation temperatures (on the order of 1300F). To have a composite material survive this environment and not be single-use is a challenge

anfractuosity12:57 PM
What's the rocket itself made from btw?

Kip Daugirdas12:58 PM
The motor casings are 6061 aluminum. But the airframe structure was mostly fiberglass and carbon fiber composite

Kip Daugirdas1:00 PM
So the max temperature capability of the composite structure is ~250-300F. Luckily it is a really poor conductor of heat.

anfractuosity1:00 PM
ah cool, and you fold the fibre glass round a mould type thing?

Alex Ryker1:00 PM
@Kip Daugirdas For someone with a workable shop (metal lathe, electronics workbench, etc.) and general engineering experience, but not much experience in aerospace specifically, what's the best way to get started with rocketry?

Kip Daugirdas1:01 PM
The airframes and nosecone are filament wound. The fins are a complicated multi-step layup. I touch on it in the video that Dan linked to earlier in the chat

Dan Maloney1:01 PM
We're about out of time, so I just want to say a huge thanks to Kip for coming on today to talk rockets, and to everyone for the great questions. I really would love to see an IRL launch, seems like so much fun. Here's hoping the next flight makes it to 100 km!

Dan Maloney1:01 PM
And I'll post a transcript in case anyone needs links or anything

Boian Mitov1:02 PM
Thank you @Kip Daugirdas and @Dan Maloney :-)

kjansky11:02 PM
What practical maximum altitude would you expect an amateur rocket to achieve

Dusan Petrovic1:02 PM
Thanks Kip and everyone who participated!

Kip Daugirdas1:02 PM
@Alex Ryker I would say join Tripoli 100% and find a local club near you. The fact that you have all of those tools puts you a step ahead of most rocketeers. A great reasource to learn about rocket building techniques online is

Alex Ryker1:03 PM

kjansky11:03 PM
Good luck!

Kip Daugirdas1:04 PM
@kjansky1 it really depends on the motors and the design of the rocket.

Alex Mi1:05 PM

Kip Daugirdas1:05 PM
Anyways everyone, I have to get back to work. If you have anymore questions I guess post them here or DM me and I will try to get them answered. Thank you.

Dan Maloney1:06 PM
Thanks Kip!

anfractuosity1:07 PM
thanks a lot!