Recent content by Benjies

Maybe I'm misunderstanding something, but given the existence of entropy throughout this system, I don't see what this theoretical cycle you are proposing "does". In the engine you are trying to convert into a helium heat exchanger, the turbine exists to drive the compressor. This is the sole...

So, first thing's first, let's see if it's even feasible that we reach ionization temperatures at the tip of an aircraft. Let's look at the SR-71, flying Mach 3.2, as a test case for your question, here. The max body temperatures found on that craft are lower than 1,000K- this is ignoring the...

To be clear- I am asking for HELP with MOC- I am not sharing this for pure information! Probably should have mentioned that in my title, or something.

'Lo all, I've been studying the Method of Characteristics for quite some time now. I understand all the interactions between characteristic lines, and how they modify the flow Mach number and direction of the flow when these characteristic lines intersect. I have just a couple of hangups that I...

Apologies if I use too many vague examples below, but I see similarities to the question you pose here, and other activities we all partake in on a day-to-day basis (in my case, music). In my opinion, both the criticism of, and the praise of, "pop sci" is valid. I'm a musician and I hang out...

The equation you have cited for exhaust velocity is not impacted by atmospheric conditions at all. You make the statement that the exhaust pressure is impacted by atmospheric pressure, and that is incorrect. Regardless of whether you are operating the engine at sea level, or in a vacuum, that...

Can I build an SSTO spaceplane if I win the lottery? Yes, you can. Go forth and conquer.

If this is for homework: 1. Run NASA's CEA code with the propellants you plan to use, operating conditions, etc. 2. Take the P/T/gamma at the throat. 3. Using isentropic flow equations (again, a gross assumption), derive Tt and Pt. 4. Take NASA's MFP equation and derive your throat area...

A couple of important notes: 1. The throat radius depends on the radius of your combustion chamber. The flow is subsonic and therefore, for the converging portion of the nozzle, we also need to know the temperature, pressure, and density of the exhaust products to avoid shocks at the throat...

Hi Abheer- turbofans will not be replaced by RDEs for subsonic propulsion. RDEs are being researched for hypersonics and alternatives to conventional deflagration rocket engines. The gains in specific impulse would have to be a factor of ten or more to make the RDE compete with a commercial...

Something else worth considering is the absurd amount of money, time, and expertise thrown at this subject. The tens-if-not-hundreds of PhD scientists who have evaluated (for their full time job, even) how to squeeze as much performance as possible out of these propulsion units have a...

You are referring to propulsion systems that are casually referred to as "deep space engines". These engines are not used for anything on Earth as the thrust/weight makes them unsuitable to move mass on earth when compared to chemical propulsion systems. In electric propulsion, your ions are...

For low reynolds flow (your very slow flow system), take a look at the selig1223 airfoil. This foil is widely used at the SAE heavylift competition. If you are limited in machinery I would instead recommend the eppler423- this can be CNC'd acceptably. But if you've got a laser cutter, take a...

One thing that would lend itself to our assessment of your writing is what this personal statement is for. Are you applying for a doctorate program somewhere? Who is your target audience? Is this a thriving school who is picky or a school with wider admissions? Also, I was lucky enough to room...

While the question you've quoted was more a demonstration of an unattainable extreme, the mission statement to 'discuss as a person of the professional scientific community' would suffice to meet in the middle between this extreme and the opposite extreme of discussing openly. Understood, thanks.