We received a special delivery of our 10" Rocket Motor this past weekend.  I want to provide a special mention to our friend and Kickstarter supporter, Tony Needham.  He and his friends helped us source the material, fabricate the motor and he personally delivered it to our shop.  With help from people like Tony, I am confident we are going to succeed in our long term endeavor!

Our large rocket motor is about 10" is diameter, 8 feet long, and has the capability to put out over 5,000lbs of thrust!  The casing is a single piece of seamless stainless steel.  The flanges are very beefy; too heavy for flight testing, but great for ground testing.  They will help both secure the test stand to the motor and provide an ideal location for our load cell, which will calculate our thrust.

Hi Everyone,

Quick Update here.  First, I'd like to show you the latest test firing we performed:

This was our best firing of our 3" motor to date!  Our two-stage test utilized two different feed lines, starting off with a low oxidizer flow rate and then switching over to a high oxidizer flow rate.  You can see the difference in thrust when the switch happens halfway through the video!  We've maxed out the oxidizer flow rate we can achieve using a 50lb nitrous bottle. 

For our next firing, we're going to:

• Replace the external SS nozzle with an internal graphite nozzle.
• Test out some thermal protect applicators to the head the motor.
• Streamline the plumbing on the injector side to move the pressure transducer closer to the pre-combustion chamber.

We've also started work on designing our 10" Motor Test Stand.  Here's a preliminary mockup:

The test stand is going to drawn up in AutoDesk (a Computer Aided Drawing program) and force-tested using ANSYS (a computer-aided engineering program), then we'll start building the platform.

My goal is to provide you an end-of-January update with another test fire video, more work on the 10" test stand, a couple of screenshots of the Hermes in AutoDesk, and some pictures of the 10" motor being built. 

I hope you're as excited as I am about all of the work being done!  Thank you for your continued support!

Over this past weekend we completed another round of testing of our 3" hybrid rocket motor testing!

This burn was very similar to the one we performed in November. However, upon attempting to increase the oxidizer flow rate, we discovered we needed to plumb our solenoid and control valve in series to achieve the flow and control we desired. The specifications & requirements were:

Nitrous Oxidizer & HTPB (rubber) Fuel
Single, circular fuel port
Port Diameter: 1.6 inches
Fuel Core Length: 34 inches
Target Oxidizer Flow Rate: 0.9 lb/s (Ideal: 1.2 lbs/s)
Actual Oxidizer Flow Rate: ~0.3 lb/s
Expected Thrust: 200 lbs (Ideal: 225 lbs)
Actual Thrust: 40 lbs
Thrust & Combustion Pressure data recorded
In-house Rocket M&C System to control all aspects of the firing.

As you can see, we saw a decrease in expected oxidizer flow rate. We are currently troubleshooting what the root cause of this could be. While this led to a very fuel rich burn, it helps show the robustness of hybrid rocket motors, able to perform (albeit not very efficiently) even in extreme ranges of O/F.  Everything else about this motor performed well, and the burn would have been excellent had our oxidizer rate been where we targeted.

One great step forward with this test was the inclusion of a bottle scale, which now gives us a continuous oxidizer flow rate measurement.  This is a great piece of data to use for analysis, and will also help troubleshooting.

We'll be doing more testing next weekend.  I'm shooting for an early January update to talk about the rest of progress made based on our December schedule (Update#14).

I hope you all have a safe and very happy holidays!

3" Rocket Motor Test Fire

Over the past few weeks, we have been working towards a test firing of  our 3" Rocket motor.  This afternoon, over the holiday weekend, we successfully fired our motor for 8 seconds!  The rest of the text below is discussion about how the test went.  Check out the video!

(Even though I was parked a safe distance away, the test fire set off my car alarm!)

Our specifications & requirements were:

Nitrous Oxidizer & HTPB (rubber) Fuel
Single, circular fuel port
Port Diameter: 2.2 inches
Fuel Core Length: 34 inches
Target Oxidizer Flow Rate: 0.5 lb/s (Ideal: 1.2 lbs/s)
Expected Thrust: 110 lbs (Ideal: 225 lbs)
Thrust & Combustion Pressure data recorded
In-house Rocket M&C System to control all aspects of the firing.

The ideal numbers for flow rate and thrust are optimized specifically for the length and size of the motor.  We chose to perform this mid-range test first as a baseline, before we moved onto the ideal.  This allowed us to use less oxidizer and make sure the control system was working properly for the 3" motor.

This test was a great success!  We achieved all of our objectives from above.  We have also further fleshed out our operations procedure and continue to come up with good ideas for how to assemble, fire and break down the motors.  These small scale test runs are crucial for figuring out what works well before we get to the large scale test firings.

December Schedule

We're hoping to get several things done in December, including:

• Performing an 'ideal' test firing with the 3" motor
• Purchasing some key components for our Rocket Monitoring and Control System
• Begin Fabrication on our 10" motor
• Put out some 3D models of the Hermes
• Make some progress on cockpit instrumentation

Thank you for your continued support!