February 27, 2018
by bluShift Aerospace
It’s been over a year since we’ve updated our blog, but it’s been our busiest year yet. After being awarded the MTI Seed Grant, the team doubled down on development of our proprietary hybrid rocket engine.
During this past 12 months we performed an amazing 140+ hybrid rocket engine tests We improved the formulation of our bio-fuel to the point where we now see a 8-16% performance improvement over current state-of-the-art fuels used for hybrid rocket engines. When it comes to designing and building a rocket, every point of increased efficiency means either more payload capacity the same sized rocket or or a smaller rocket with lower costs can be made.
Our engine tests continued into the winter, and as you can imagine, weather conditions in Maine were less than friendly at times to basic logistics of carrying out those tests. We encountered everything from 18? of snow blocking our access to thick ice locking up the entrance gates (requiring the use of a propane torch).
Normally after an engine test the outer casing was too hot too touch for more than a few seconds. But in the depths of the Maine winter, we found ourselves soaking up the heat through our insulated leather gloves just to get our fingers moving again to change out the fuel grain. It’s no wonder most rocket companies are conveniently located in warmer climates. However, being Maine-tough has its advantages. Those great temperature swings helped us make a discovery…
From 90°+F in the summer to -20°F in the winter, our fuel grains were exposed to a wide temperature range, causing them to expand and contract. Two things would happen – cracking and fuel casing separation. Neither of those are desirable for our ultimate rocket. So in the depths of the winter we dived in to solve these challenges. It took about 40 iterations but we finally landed upon a solution. We made some changes to our fuel casing and the composition of the fuel grain itself that prevented separation in even temperatures of -112°F and minimized the cracking to the point where the fuel would not separate from itself.
Without the challenges of the Maine season we probably would have never tackled this challenge. But you might ask – why are temperature swings even important? All you have to do is think about the great temperature swings a rocket will experience throughout its flight – even if it’s launch from the cozy temps of Cape Canaveral. At launch it could start off in high humidity and the upper 80’s. But during the final phase of the flight the last stage experiences the brutal sun on one side but the deep chill of dark space on the opposite.
Or, as CalTech and NASA has imagined it, you could deploy a hybrid rocket on to the surface of Mars to send back surface samples back to Earth. While it’s waiting on the surface for months at a time temperatures can get down to as low as -100°C (-148°F). Be sure to catch Dr. Ashley Karp’s Mark 2017 lecture covering the topic here.
(oh, and yeah, Maine is still not as cold as Mars is in the winter ;))
The bulk of our 140+ tests took place in a smaller test rig. This test stand enabled us to rapidly perform the fuel recipe test iterations and reduce the costs of fuel and oxidizer. Now that we have narrowed down a formulation which excels, it is time for us to perform larger tests in our vertical test rig increasing the engine size. The focus of these upcoming tests is less on the formulation of the fuel but on improving the efficiency of combustion. And then it will be honing the performance of the rocket nozzle itself.
Standing at 18 feet tall, our vertical test stand better simulates the thermodynamics of a hybrid rocket engine that’s about to be launched. This setup is as compared to the traditional horizontal test stands frequently seen in smaller rocket engine tests. Since we’re working on a hybrid rocket, the combustion chamber is encased in the fuel itself – fuel which melts and drips. A horizontally mounted engine will hide some of those dynamics and the issues it can cause, whereas you can more readily see them when the engine is vertical.
In 2017 we performed a shorter series of tests using that vertical test stand but we immediately encountered two issues: 1) stability of combustion and 2) reliable ignition. After a blow-out that damaged the injection bulkhead we back-burnered test rig in favor of the small, faster iteration test stand.
As of April this year, we finished repairs on the vertical test stand. We improved the design of the injection bulkhead. And to our delight we ramped up the volume of the oxidizer injection without notable combustion instabilities. Last but not least we improved the ignition reliability. However, we still have a ways to go to meet our goal for reliability.
Once we have completed optimizing the efficiency of our rocket engine and the nozzle, we will be moving to an exciting next stage – building our first proof-of-concept rocket, name the Brown Dwarf 5! As early as 2019 we hope to test launch the rocket up to 15,000 feet. Then, a few months afterwards, launch it to space and back as a sounding rocket with a 5kg payload.
Once this demonstration rocket has successfully launched, bluShift will push ahead in the development of its nano-satellite launch vehicle (aka rocket), the Red Dwarf 50. A 3-stage rocket, it will be capable of carrying up to 50kg of these small satellites, commonly referred to as ‘CubeSats’, into low Earth orbit. More on that to come in upcoming months.
Internally, many of us wear bluShift gear all the time – whether its at the test site itself, taking a run in the woods or enjoying a brew at the local Flight Deck here at Brunswick Landing.
Now you too can get bluShift T-shirts, mugs or even a bluShift emboldened baby Bodysuit! A portion of the sale of each item will go to help fund our research, development and eventual launches of these Maine-made rockets. Click here to buy your bluShift gear today!