A High Power Wood Rocket In 5 Days

Getting started with model rocketry is relatively cheap and easy, but as you move up in high power rocketry, there are a few hoops to jump through. To be able to buy rocket motors larger than H (160 N·s / 36 lbf·s impulse) in the US, you need to get certified by the National Association of Rocketry. The main requirement of this certification involves building, flying, and recovering a rocket with the specific motor class required for the certification level. [Xyla Foxlin] had committed to doing her Level 2 certification with a couple of friends, thanks to the old procrastination monster, was forced to build a rocket with only 5 days remaining to launch data.

For Level 2 certification, the rocket needs to fly with a J motor, which is capable of producing more than 640 N·s of impulse. Fortunately [Xyla] had already designed the rocket in OpenRocket, and ordered the motor and major body, nosecone, and parachute components. The body was built around 2 sections of 3″ cardboard tubes, which are covered in a few layers of fiberglass. The stabilizing fins were laser cut from cheap plywood and were epoxied to the inner tube which holds the motor and passes through the sides of the outer tube. The fins are also fibreglassed to increased strength. For a unique touch, she covered the rocket with a real wood veneer, with the rocket’s name, [Fifi], inlaid with darker wood. The recovery system is a basic parachute, connected to the rocket body with Kevlar rope.

[Xyla] finished her rocket just in time for the trek out to the rocket range. She successfully did the certification flight and recovered [Fifi] in reusable condition, which is a requirement. There was nothing groundbreaking about [Fifi], but then again, reliability the main requirement. You don’t want to do a certification with a fancy experimental rocket that could easily fail.

Rocketry can quickly become a deep rabbit hole, where sending a rocket all the way to space or getting one to land like the Falcon 9 is within the realm of possibility. On the design side, there is also now a rocket workbench for FreeCAD.

30 thoughts on “A High Power Wood Rocket In 5 Days

  1. Not what I expected from the title but still cool. But the title did get me thinking, do you think you could make a wooden hybrid rocket? You know use the wood as the rocket body and fuel and burn up the rocket for thrust?

    1. Adding lots of oxygen to make it burn well absolutely. I think it would have to be a larch for the outer body of the rocket, nosecone etc – something that really doesn’t burn easily (and larch as far as I’m aware is one of the best woods for as it just chars when you heat it, it is rather hard to ignite properly (though may well be better woods out there)). Then something soft, and easy to ignite with pretty consistent grain pattern, perhaps a high resin content like pine, or even something like MDF for the ‘fuel’ section. Would need a small oxygen tank, pressurised so metal, or a void in the nose filled with liquid oxygen and a small feed hole for the all wooden rocket experience.

      I expect a great many catastrophic failures before getting it right though, or a really poorly performing rocket – use too much of the more durable outer shell wood and its going to weigh too much ‘dry’ to perform well, get the oxygen flow wrong its not going to be anything but a pressurised gas rocket or pretty little flare like object on the pad… And wood being a natural product the safety margin required so it reliably doesn’t fail under the pressure vs the weight/thrust ratio and centre of pressure/mass to make it function properly is probably rather slim…

    2. The biggest problem with using the body of the rocket as fuel is the lack of control of combustion.
      If you just cored out a wooden dowel or body to burn, any defects or compromises in the grain could burn faster than other areas and compromise the structural integrity of the body.

      If you had a weak spot and the combustion burned through the outside of the body, you could lose pressure and thrust, or even have a blowout causing unstable flight and breakup at velocity.

      Wood also won’t hold up to chamber pressures too well if the fuel consumed too much of the structural component of the rocket, also potentially causing a blowout or disintegration.

      You could still potentially combine a fuel core and burn up some ports of the rocket (staging?)
      You could make a composite fuel assembly with sawdust and acceleratns into a fuel grain to control combustion, but I have no idea if wood would burn reliably, or efficiently enough to make up more than a small fraction of the fuel composite.

      If you are interested in more theory about amateur rocketry (more DIY) then this site is a bloody amazing resource!

      This page on fuel grains is a really cool read as well and can help illustrate burn rate and considerations on fuel grain and stability.

      1. Thanks for the references. The idea of a rocket body also being the rockets fuel just seems sweet to me, if your launching the support structure anyway why not use it for fuel.

        1. Wood can certainly be used as a fuel grain in hybrid rockets. In fact it often is in micro and mini hybrids. If you buy a micro hybrid from Lee Dexter he includes a guide that covers how to make fuel grains from various materials like paper, wood, and short sections of plastic pipe. Practically anything combustible will work.

          The problem with the idea of making the whole rocket body the fuel grain is 2 things. First of all, both NAR and Tripoli require your rocket to be recovered. The entire principle of model rocketry is to launch a rocket that can be recovered and launched again. A rocket that’s consumed does not meet this requirement. A rocket like that would violate the rules and be considered more like a missile or a pyrotechnic. In fact, if a rocket isn’t recovered in a condition that can be flown again, you fail your certification. In the article it mentions this was her certification flight. If this was the case, she would have fail to certify.

          The second problem with this idea, is how do you implement a nozzle? The nozzle on a rocket engine is rather important for performance. It accelerates the flow of gases and greatly increases performance. If the nozzle burns as the propellant grain burns, how does it continue to function? That’s why the nozzles are typically made of materials that can withstand high temperatures, at least long enough for the fuel grain to complete it’s burn.

          Anyway, I don’t think a hybrid can be used on a certification flight anyway. Usually, they are considered research motors. On certification flight only pre-certified motors (motors that have been tested and certified by either NAR or Tripoli) can be used. Also to even launch a rocket with a research motor, you must already be level 2 certified and the event you launch at must be classified a research launch event.

      1. Really? In the 40’s? So they had crazy people in the past too. Still from what was said above I can see the mixed results, but we see farther than others because we stand on heaps of smoldering wreckage. (Sort of break it till you make it.)

  2. While nothing ground breaking, still the rocket wasn’t a ‘store-bought’ kit. I liked the wood accent, never would have thought of that. Having your own laser cutter to cut parts is a sign of the times too. I went the simple route back in 2007 with a Patriot kit (parts all supplied) for level 1 certification, so didn’t have to go through the amount of work Xlya went through…. I knew it took me a few more days to complete and paint my rocket. Of course I had/have a pesky day job…. I couldn’t just build and play for 5 days! I didn’t take it any further up the cert chain. Anyway neat job well done for level 2!

    1. I’ve noticed that wearing a lousy mask has significantly helped with allergies during tree and grass pollen season this year. It’s also the cheapest sunscreen I can buy.

      I bet very few masks are adequate for rocket smoke or Black Rock Desert dust, however.

  3. While an all wood rocket might be an excellent way to make night launches even more exciting, a more conventional NO2/sawdust & wax motor might have some chance at working.

    1. I think you mean N2O; NO2 is nasty, nasty stuff. And such a motor would not be permitted except at TRA “Research” launches. NAR allows only commercial motors, no homemade stuff.

  4. I enjoyed the video and was impressed with the combination of demonstrated skill and entertainment. While I have had friends who are into amateur rocketry, for some reason I never picked up the bug. What does level three certification involve/allow?

    1. L3 certification involves building and successfully recovering a rocket powered by an M (5120-10240 Ns), N (10240-20480), or O (20480-40960) commercial motor. There are other requirements such as review by members of a special committee during construction, redundant deployment electronics, etc.

      L1 certification allows the rocketnut to buy and use H (160-320 Ns) and I (320-640) total impulse. An L2 user can fly J (640-1280), K (1280-2560), and L (2560-5120) motors. All certification flights require the use of commercial motors; however, Level 2 and 3 fliers in the Tripoli Rocketry Association are permitted to make and fly homemade motors using ammonium perchlorate composite propellant—essentially the same stuff used in most of today’s solid space boosters. (NAR members are not permitted to use homemade motors at NAR events)

      FWIW it’s the Natiional Association of Rocketry; NRA is a different beast. :-)

      Most NAR members fly smaller rockets, up to G impulse. Tripoli members focus on high-power, H and above. Some very interesting things are being done. Two years ago a 2-stage rocket was flown at the Black Rock Desert to 140,000 feet. Second stage did a bit of a corkscrew; had the flight been completely successful it might have reached 100 km—space.


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