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.
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
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. ;-)
Where do you get nitrous, that’s got to be illegal or something, right ?
whipped cream propellant, they come in little canisters shorter than a co2 cartridge
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.
hi we are looking to develop a rocket powered micro system for a bike to do tests all welcome as we will build prototypes at our school abroad
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.
http://www.youtube.com/watch?v=TLPWqCMb7DE
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?
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.
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
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.
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?
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.
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
Just a thought, but maybe one should spray one’s PVC rockets with metal paint, to help it show up in X-ray. Plan ahead right?
Yes PVC will splinter in pieces when over pressurized. However the pieces being light weight will travel less distance than say iron pipe pieces would travel. I have seen jokers on youtube using regular old galvanized pipe for their motor casings! The trick with PVC motors is do not try to achieve maximum kn from them. Going cheap is for quantity of flights for entertainment value not for setting altitude records!
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)
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.
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..
No it won’t
Was wondering if anyone has tried oil and nos as fuel for rockets. I think it might work but haven’t got the materials or money too try it.
can you make them outta old propan map gas tanks and luse a stepped drill bit to make the nozzle where the shradder valve is dont say thats just downright dangerous it could explode on you and send thousands of tiny fragmented metal particles faster than the speed of a buck snort when you pull my finger and kill you its got a saftey mechanism built into the thing to relieve pressure so
That valve would release the pressure if it built up gradually, however rocket ramp up pressure so fast the valve could not release it fast enough. At least with solid propellant mixtures that is. This is where you need to carefully consider the burn rate of your chose of fuel and how chamber pressure affects its burn rate.
One trick is to calculate the pressures your motor design will be achieving and stay below what the size pvc pressure rating is. Also do not make the nozzle or the forward end plug too strongly attached so in an over pressurized event they should fail before the casing fails. Also when I test mine I have a secondary cage to trap any pvc fragments if this occurs. And of course I’m in a bunker while igniting a test motor and do not watch it live! I record it with cameras and review it after testing!