High powered rocket engines made from PVC pipe

rocket

For as much as we enjoy rockets, explosives, and other dangerous things, we haven’t said a word about the works of [Richard Nakka]. He’s the original hacker rocketeer with thousands of words dedicated to the craft of making things move straight up really fast. One of his more interesting builds is his series on building rocket engines out of PVC pipe written in conjunction with [Chuck Knight].

For the propellent grains, the PVC rocket didn’t use the usual potassium nitrate and sugar mixture of so many homebrew solid rockets. Instead, it uses Sorbitol, an artificial sweetener. While melting and casting the Sorbitol-based propellant grains is much easier than a sugar-based concoction,  the Sorbitol had much less thrust than a typical sugar rocket, making it the perfect candidate for a PVC engine.

For those of you wondering about the strength of a PVC engine casing, [Richard] does say making larger rocket engines out of 2 or 3-inch PVC may not make much sense due to the increased chamber pressures. There is a fairly clever reinforcement method for these PVC rockets (PDF warning) that involves using PVC couplers, but the experiments into the strength of these casings have yet to undertaken.

Thanks [Caley] for sending this one in.

Comments

  1. geekmaster says:

    At first I thought this was going to be about rockets that use PVC as the FUEL. But no, just a containment vessel.

    There are some pretty large rockets out there that use nitrous oxide as the oxider, and PVC pipe as both the rocket body AND AS THE FUEL. They consume themselves somewhat in flight!

    Now THAT is what I call a “hack”! ;-)

    Here is a small kit that demonstrates that design, using NO2 whipped cream chargers with acrylic tubes:

    http://www.aeroconsystems.com/motors/Screamer_folder/screamer.htm

    • rockets4kids says:

      Dan Pollino has a dual-fuel version of the sugar-PVC motor which starts out burning sugar propellant and when that is completed, he injects nitrous to burn the PVC casing.

      That is what *I* call a hack. ;-)

    • smee says:

      That, that is just awesome. Best comment in months. God I wish I hadn’t moved away from rockets over a decade ago. So much cool stuff to do that wasn’t known or available then.

      My real problem is I lack the really large area required for big’uns. Maybe I can dream of someone more knowledgeable than me posting a cheap HALO system.

    • Alex says:

      That’s what I expected to see, too. Ben Krasnow built a rocket motor that way, it’s clear so you can see inside when it runs. Very cool.

  2. Willaim says:

    Wouldn’t it be better to use a continuous length of PVC pipe instead of short pieces joined by couplers and instead take out the rib in the middle of the couplers?

    • smee says:

      I have done this very thing. Not to make rockets, but to get thicknesses I want.

      What would be even better to increase strength is to heat up some wire and embed it into the pipe, then apply couplings over it. Some people have tried cutting then boiling pvc in oil to make it malleable enough to form over a pipe. Theoretically it could be fine to do outside, but I just think it isn’t a good idea.

  3. buzzles says:

    If you want to see some more about pvc rockets (and “rocky candy” fuel), then I think this site might be ok, think it’s been on Hackaday before: http://www.jamesyawn.net/index.htm

  4. rockets4kids says:

    A quick word of warning before anyone gets too excited about building large PVC motors: There are very few places where you can legally launch them. I am only aware of one club in the entire United States that allows the use of PVC motors.

    While it is not terribly difficult to build a rocket motor in PVC, most people seem to produce quite a number of smoke bombs or pipe bombs before succeeding with a working rocket motor.

    As such, there is a *huge* amount of hate directed at PVC motors and the people who make them. You have been warned.

  5. BLKMGK says:

    Curious – would it be lighter and still increase strength to wrap the pipe with monofilament line? sort of like boilers on some steam cars were reinforced ages ago except nylon vs stainless steel wire? Heat would still be an issue and wrapping it evenly should probably have some automation to it but I wonder if the strength increase would be worthwhile. Thoughts?

    • David says:

      My thoughts exactly, particularly after just reading a newer HAD post about a carbon fiber wrapping machine. BTW, while researching converting autos to CNG, I noticed that the fancier CNG tanks are reinforced this way to make them lighter and/or stand up to higher pressure.

  6. Ted says:

    Be a little careful with this one. Many people in the legitimate pyro community (those with BATF licenses and expertise) used to say that PVC was dangerous. When accidents occur (and they do) it splinters and the pieces are pretty transparent to medical x-rays

  7. I have had success with wrapping fiberboard tubes with fiberglass packing tape as the final touch in order to keep them from exploding. ( Start with manila file folder paper glued up, rolled, into thick walled rocket motor tubes 1 to 1.5 diameter)

  8. Greg Zsidisin says:

    This comment comes long after the original discussion, but: PVC is not without its hazards. When it fractures, it produces very sharp and dangerous flying pieces. Less-common HDPE (high density polyethylene) piping is used as a safer alternative. For example, it’s the preferred material for fireworks mortars (launch tubes).

    I would also put in a plug for John Wickman’s “How to Make Amateur Rockets” book and software set (http://space-rockets.com/newbook.html). The software allows you to design and model solid rocket performance.

    And then there’s John’s rocket motor-making class (http://space-rockets.com/ae101.html). It’s a fun 3-1/2 days of rocket theory and “arts and crafts” as you design, construct, and test-fire a solid rocket considerably larger than a model rocket engine.

  9. I think duct tape would make a good reinforcement for pvc.. At least if it blows up the pieces will stay together and the tape may prevent an explosion even if the pvc cracks under pressure..

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