Defining Project Parameters

 For our project, we want to achieve the following:

• Choked flow and stable combustion in a rocket engine 
• Propellants are pump fed
• Pump is driven by a gas
• Ablative thrust chamber

The pump design phases are as follows:

Phase 1: Helium* Turbine and Water pump

Phase 2: Helium Turbine and Liquid Nitrogen pump

Phase 3: Gas Generator Development Water pump

Phase 4: Gas Generator and Liquid Nitrogen pump

Phase 5: Turbopump Design and Assembly 

The decision was made based on the idea that our project needs to be as simple and specific as possible. Everyone on the blog has experience building an ablative thrust chamber and by getting rid of more complicated thrust chamber cooling options, we can focus on the turbopump. Furthermore, by taking smaller steps in our pump development, we can tune our calculators, learn basic pumping principles in a safer and more controllable environment, and have more time to gather information on gas generator ducting and turbine blade materials. The incremental testing campaign outlined above also allows us to generate a plethora of data points around both the turbine and pump for iterative design and testing in a hardware rich environment. 

*Helium can be replaced with any inert gas in any phase

Our path forward in the next few days is:

Start Github for pump calculators, research what our final working gas will be for the gas generator  - steam heat exchanger?? (and update shaft configuration), start designing our pump test stand (P&ID, wiring diagrams, BOM), post weekly progress updates on blogger. 

Zach - Pump calculator

Ryan - Turbine research

Dylan - Test stand and steam research

Update to Turbopump Page!

 Updates have been made to the turbopump page! Click this link to check it out. The page mainly covers pump history and pump design and will soon go over turbine design. 

source: Oleg Baturin

Pump Component Materials

Just a quick note on turbine blade and ducting materials. I've found that Hastelloy - X, Rene - 41, Mondalloy, Nimonic 90, Inconel 718, and Haynes 282 are all common materials used for turbine blades, housing, and ducting. In particular, Inconel 718 and Haynes 282 (or Hastelloy - X) are more common and more available, with both materials available on McMaster - Carr. There's also a few vendors, like Turbocam, that have the capability to machine or print in these materials. 

Credit: Zare Materials

- Zach

Thoughts on a Gas Generator

While an expander cycle is an attractive option, mainly because of the simplicity it brings to system plumbing, it comes with a few disadvantages. 

1. Pump can't be operated independent of the thrust chamber (regen required for operation)

2. Spin up is more difficult (requires some preliminary heating element for the cryogenic fuel)

3. Limits design to a few cryogenic fuels (LH2/LCH4)

4. Uncommon/not as much research

Further research has revealed that an open cycle gas generator is much more common and likely more attainable. NASA's Fastrac program, in partnership with Barber-Nicols, yielded the development of an RP-1/LOX engine that paved the way for the development of SpaceX's Merlin engines, an open cycle gas generator (GG) design. Using pumping affinity and similarity laws and the vast amount of data on this engine, it becomes much easier to develop our own turbopump.

Additionally, to simplify the configuration of our turbopump, a single shaft design or parallel dual shaft system, may simplify sealing and gearbox challenges (at the caveat of more complex plumbing to route gas generator exhaust to two turbines). Additionally, a gas generator requires a much more robust alloy or super alloy for the turbine blades. Such alloys include nimonic 90 and other titanium alloys, which can be difficult to obtain and machine. 

Figure 1: Pump Configurations

Furthermore, turbopumps of these kinds have a rich history, with the Redstone missile using a gas generator powered by the decomposition or hydrogen peroxide to pump alcohol and liquid oxygen. Additionally, online databases have a large number of photos and diagrams providing valuable insight as to how components fit together and operate (Heroicrelics has some incredible photos of the F1 Engine turbine and pumps). 

Figure 2: Redstone Turbopump

A trade study is underway to determine the best option for our application. We'll evaluate different pump configurations and engine cycles mainly on how relatively easy they are to build and how well they can be produced for a reasonable price. 

Figure 1: MODELING AND SIMULATION OF LAUNCH VEHICLES USING OBJECT-ORIENTED PROGRAMMING - Scientific Figure on ResearchGate. Available from: https://www.researchgate.net/figure/Turbopump-configurations-SOURCE-SP-8107-1974_fig7_322924066 [accessed 3 Oct, 2021]

Figure 2: http://heroicrelics.org/info/redstone/a-7-turbopump.html

-Zach

Considerations Using an Expander Cycle

One of the primary goals of our project is to use a turbopump to feed our propellants into the combustion chamber. While there are many different options, a rocket engine that uses an expander cycle is looking to be more viable for our application. 

Expander cycles have a few main advantages:

• They use expanded gas from your regen channels, allowing cooler gas temperatures to be used in your turbine compared to something such as a gas generator
• They scale well for smaller rocket engines
• There are variations that can simplify your turbopump assembly

One such variation is the Open Expander Cycle, in which your propellants are used by the turbine and then dumped downstream of the nozzle exhaust. This has the advantage of using your turbine exhaust gases without also worrying about back pressure on your turbine (if you were to route the exhaust to the chamber).

Credit: NASA/wdgreene

Another variation is the Dual Split Expander Cycle. This has the advantage of keeping both the fuel and oxygen pump separate. This simplifies bearing and seal design at the trade of having more complicated engine plumbing. 

Credit: NASA/wdgreene

It's also worth noting that these engines have been getting more recent attention, with Mitsubishi Heavy Industries producing the LE-5B engine running on a similar expander bleed cycle.

Credit: Mitsubishi

In summary, a trade study is in order to make more informed decisions on what combustion cycling may look like on our engine and if combining the two variations above would work.

-Zach

Brainstorming

INTRO

The goal of our project is to push the boundaries of amateur propulsion. By tackling some of the most complicated systems associated with rocket propulsion, we hope to learn and help others learn what makes a rocket engine a good rocket engine. 

Performance

- 250+ specific impulse 

- 1000+ lbf

Thrust Chamber and Feeds

- pump fed

    - expander cycle? (won't have to worry as much about turbine melting)

        - Expander bleed cycle (only some prop is heated and used on the turbine, which is then dumped overboard)

    - open cycle gas generator?

    - tap-off cycle?

- possibly throttleable?

- regeneratively cooled

    - film cooling? Ablative? Heatsink? WATER?????(jk)

- printed or machined chamber

    - electroplating copper

    - machined jacket

    - composite jacket

    - CuCrZr print

Propellants

- LOX paired with LNG, RP-1, IPA, Ethanol, Methanol (some hydrocarbon)

- GOX/Nitrous for something more tame (should we avoid cryo?) No :)

Igniter

- Acoustic

- Torch

- Hypergols ??? (Turpentine and Nitric Acid)

- Fuse/solid motor 

Injector

- Swirl

- Pintle 

- doublet impinging

Testing

- test out at FAR?! one summer

- LN2 cold flows with turbopump

- injector water flows

Welcome!

 Welcome to Rocket Lads! 

We're a group of students looking to redefine what's possible for amateur rocketry. Check out the "About Us" page to learn more and the "Project Overview" sub-page to get a taste of what we're doing. 

We hope you enjoy this project as much as we will!