IamA rocket propulsion engineer for Airbus AMA!

How much of your work involves using theoretical materials and products? For example, do you ever design something that requires X lightweight material or Y superfuel or whatever, even though X and Y don't exist yet?

No, we don't dream that far in my department. We are looking into technologies that might fly on Ariane 6 or in spaceplanes. We try to take avaliable technologies and raise their TRL from 3 to 6. Those kinds of thoughts use TRL technologies of about 1 or 2.

What prevents big planes from going faster? Will we ever see airbus planes going at Concorde speeds?

What can we expect as far as speed is concerned, in the near future?

Thanks.

Well, energy is a big factor as the air resistance rises exponentially with the speed. You need big engines and a lot of fuel.

Then the market needs to be right for this kind of plane. At the moment the market is more focused on fuel consumption, luxury and price per passenger per mile. I was quite surprised when I heard the A350 the first time, it's pretty quiet.

Do you frequently utilise Solidworks at work?

Ex Aero Eng M.eng student. I fucking hate it. FEA is cool but seeing "this feature cannot mate" 1000 times a day god damn

YES YOU CAN YOU FUCKER. YOU DID YESTERDAY.

I don't use it, as I'm not doing construction, but even then it's more Catia

I work in design for Airbus DS, we use Catia V5 (soon to be V6) .

Man, didn't you get the memo? We're not supposed to use any abbreviation of Defence and Space :D

Where are you based?

Whats the best rocket scientist joke or quip you know? And how do you refrain from saying "Trust me I'm a rocket scientist"?

Actually I don't like the term "scientist" that much, I prefer calling myself rocket engineer, but of course it slips out sometimes.

My favorite joke:

Whats a rocket engineer? - Someone with his feet firmly on the ground, his head in space and his hands in the taxpayers pockets.

Very nice, thank you for your time.

I like to yell "Trust me I'm a doctor" I fix computer things in a non medical field.

Edit: I think you should throw out "I'm a Rocketeer" everyone once and a while.

Yeah, the only place I could apply that phrase that comes to my mind is the middle east, and I don't think I'm allowed to go there

Which specific part/component do you work on? How much do I have to worry about you getting it fault-free?

(Did you start this AMA as soon as you realized Portugal had no chance?)

Yes, yes I did :D

I work on the thrust chamber and the technologies that go with it.

Fault-free is not so important at our level, no one gets hurt if a test bench blows up, it's just money. We rather try to test to the limits than not know where the line is

What are the limits of what you do? Are you refining internal combustion systems or looking at alternate models of propulsion altogether?

It's more a refining, making small changes on the design, sometimes a few on a new engine, never that much, a rocket is expensive

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Yes, we look at turbopumps as well, although not my focus. I work more on combustion chambers. Yes, system wide change is hard to push through.

Don't know if you're still reading this, but there was a discussion here about how 3D printing has reduced costs of rocket engines drastically. As I mention in that comment

IIRC, the superdraco has a single piece combustion chamber + injector

Have you worked with/studied both types? Conventionally manufactured, and 3D printed ones? (Injectors and combustion chambers). Could you comment on the differences?

Yes, we have, the major differences are in design, the direction of the layers is crucial.

The powder that stays in the channels and on the walls is a pain to get rid of, if you don't do it properly, you get all kinds of problems, but mostly colored flames :D

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Eagerness to see them perform - the first few years are critical, but it seems like they're here to stay-

We know we can't be SpaceX, but we watch them closely and try to learn. The US-business is different from the European one

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How you manage your first real failure depends on how much you will be trusted in the future. Failures happen, you just have to treat them the right way

Don't you fear what they could so to your market share? They seems much more "lean" than Airbus that still hasn't gotten rid of all its old "public company" traits.

True, but we serve a slightly different market. You'll see the Ariane 6 will be more like Ariane 4, but cheaper. We try to compete for the overlap in markets.

A big market is the US Defence budget, only US companies get access, and SpaceX has just entered it. Other US companies will have more trouble adapting

What has been your most memorable day at work?

Driving a company car for the first time and getting a ticket for speeding - can't live that down

Well you are a rocket propulsion engineer, making stuff speed up is literally in your job title.

I'll remember that one next time the topic comes up

So, rocket science- is it really as hard as the popular aphorism suggests?

How did you get to where you are now? Model rockets, a love of engineering...?

A love of engineering and some luck.

It can be quite tough during studies, we had lots more fluid dynamics and thermodynamics than other engineers. Once you get the hang of those two it's fairly easy. It gets really easy once you get a job.

Seriously, how does a plane fly? All of that curved top of the wing stuff with there being lower pressure air going over because it's going faster-apparently that's bunk?

Yes and no. Planes fly because they transfer impulse to the air. The impulse forward with the engines accelerating the air. The impulse upwards with the wings. So much for basics...

...the hard part is talking about HOW the wing does it. Yes the pressure stuff is true, but it's not everything. Redirection of air flow also gives an impulse. Then you have vortices and everything gets more complicated. But you get the idea - Impulse

And those upturned wing tips. Decoration?

Nah, reducing vortices and thereby air friction or something something

And what about the plane on the treadmill problem?

Oh God, why are you planes so complicated?!?

Have you met rocket engines?

Yeah, Mythbusters explained that one. But with the information given above, you should be able to understand. An aircraft is only giving impulse to the air to accelerate, unlike a car, which gives impulse to the ground to go forward :)

Thanks for doing this! What space propulsion technologies are you currently working on?

I'll try to keep it a bit vague, you'll have to excuse me. We're working on new igntion systems, new materials and new injectors. I'll add a good site to the post in a sec

What degree did you do in university... And how good is the pay on the job? :P

I studied aeronautical engineering in Germany... Pay is pretty awesome, I get more than I deserve :)

Do you play Kerbal Space Program?

Yes, I discovered it in my holidays before starting my job (2 years ago) and even though it was sunny that summer I only got a screen tan ;)

Do you ever catch yourself at work saying "It's not like it's rocket science! -Oh wait." -?

Nope, never at work, sometimes when other people boast

Have you ever heard of electrogravitics?

Yes, freaky stuff

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Keep focused when you need to, no need giving 100% all the time, that way you don't have reserves when you need 150%

What is stopping mankind from building faster rockets? Will we in our lifetime have spacecrafts traveling at like 1 million KM/hr?

An energy source. with electric energy you need a nuclear power station to get the power to lift off. Once you've got that figured out, the sky's the limit.

And I hope so, but I don't think so

I'm currently a junior pursuing a bachelors and masters in Mechanical Engineering at a top engineering school in the US. What you're doing sounds exactly like what I want to do. Do you have any tips or suggestions to help me get there?

Get a network together, go to conferences, ask your professor about possible jobs, find out who might hire and what they expect/need.

In my case it was a lot of luck and fun. I chose the space courses because they were awesome and because I had my combustion specialization as another option. I never expected to get this job

Are there people working on this problem? http://xkcd.com/1382/

Serious question: What application for a rocket would you be most happy to see or construct?

Nah, we don't do calf shields, that's someone elses problem :) And no, we don't do rocket jetpacks, unfortunately. I would like to build one though, so yeah.

More seriously, I'd like to see a super-heavy launcher in my lifetime, something that puts more mass into LEO (low-earth orbit) than the Saturn V (around 120t to LEO).

Do you ever visit the Filton site? I'm currently there on a 6 month contract.

No, unfortunately not, I have a friend working there, but as I'm not in the aircraft divison, it's very unlikely

Is your job difficult? I mean, it's not exactly brain surgery...

If you're having fun, nothing is difficult, so no :)

1. i really curious about why this plane's range is much more shorter than this giant. isnt it unlogical?

2. do you think U.S dominate the air industry(i am asking because of electrcal component makers for planes like Honeywell, Rockwell Collins, P&W and GE)

3. what do yo thinnk about air industry, generally

1. Well no, not illogical, you can have business jets with more range, it all depends what the market wants. If your customers don't need to fly long distances you design your aircraft that way. Smaller fuel tanks need less structure and efficiency is everything

2. No, they are the biggest player, but not dominating. Although ITAR can be a pain in the ass for components

3. They fly too low ;)

What's a typical day in the life of a rocket engineer like?

It's an office desk job most of the time. During test campaigns it gets more fun as we get to handle some hardware and make some noise. So either 9 to 5 or 7 to 7

What are the primary domains in which you seek to push innovation?

By which I mean - alternate fuels? alternate physical designs? alternate materials?

Thanks for taking the time!

Alternate materials, alternate designs mostly, but also different fuels. Hydrogen, Methane, and Alcohol, to name the most popular at the moment

Does the work ever feel like it's too hard? are there times when you're given a problem or task that you just can't solve or achieve? If so, how does something like this play out?

Rarely - hard problems are usually not solved alone. It's mostly trying to get stuff done in time that make is hard

my good question deleted by a wideass mod. so i will change it's shape and ask again. which one in these tree space agencies you want to choose and say why you chose it?

• esa
• nasa
• jaxa

I guess you mean which one is the best. Simple - NASA, they are only governed by one country and they actually did stuff.

Not ESA because they're a bit too complex and less ambitious. Not JAXA, because they do even less.

All answers deeply subjective :)

is doing-stuff means going moon? sending vehicle to mars? or what? but others doing stuff too. for instance this or this. ESA look like more scientific though.

i think NASA doing more cause it's $17 billion budget.

The space shuttle was dominating the space age, just think of that. ESA has some way to go. JAXA only launches twice a year and that rocket isn't finished yet ;)

I'm going to college for Physics. Is it possible to get a job like yours or would a more specific degree be required?

Probably not in my department, but in System Analysis or Modelling you might have more luck. If you can't do engineering or fluid dynamics it's rare. Some of my colleagues in electronics or optics have a Physics degree. So space science is definitely possible

How do you feel about Roy Orbison - specifically his 1979 album "Laminar Flow"?

While I did listen into some songs on youtube, I have no specific feelings, sounds like 70's music

ha ha. It is.. it is. I was going to ask about my weird habit of choosing not to sit next to the engines on a commerial aircraft just in case something snaps and comes flying through the fuselage. I like to think I'm avoiding additional risk by doing so, but it's probably far less likely that an engine will explosively disassemble itself than it is for another human being to attempt to bring down the aircraft intentionally. So yeah. I asked about Roy Orbison because I didn't want to come off as some kind of paranoid lunatic.
Thank you for looking, though! Hooray for Rocket Appliances!

Don't worry, the engines have a protection around them to avoid fragments flying everywhere. But sometimes the fragments are a bit bigger :)

American 767 At LAX June 2, 2006 American Airlines Boeing 767 doing a high power engine run had a #1 engine HPT failure. HPT let go and punctured left wing, #2 engine, peppered fuselage and set fire to the aircraft. The turbine disk exits the engine and slices through the aircraft belly and lodges in the outboard side of the #2 engine.

(HTP = high pressure turbine)

Awesome picture

But don't worry, that rarely happens, terrorists have kidnapped your plane a lot until you get sliced by engine parts

What is the effective(or specific impulse) and actual exhaust velocity of a rocket you're working on? Gimme some details, I understand that stuff, 'couse I make my own rockets (well solid fuel ones, of course). Also what system of units do they use? long live metric system.

ISP is around 420s - hydrogen makes it go :)

We actually use both, mostly metric though. Some parts are cheaper in imperial, so yeah

Glad to hear that. You use expander or staged combustion cycle? And are there plans for these rockets to be reusable? Also what are intentions for these rockets? Orbital launch vehicles? If so what type of staging? Personally I think 2 stage with boosters is the most efficient one.

Vinci, the upper stage is an expander cycle. We have worked on staged combustion in the past, but there is no active project. Mostly launcher engines, so first and upper stage. Small thrusters are also being developed, monoprop, biprop and electric. These are used for ARCS and satellites.

We don't perform system analysis of the launcher, so I can't tell you what staging for what mission is best

So... Is it rocket science?

Yes, yes it is :)

Did the cancelled order from Emirates affect you?

Me personally not at all, I can't speak for the company

Thanks. I was wondering if they were separate companies when it comes to budget or they share the incomes... btw how's the atmosphere with the 4-0 over Portugal?

Well, it's a group with three relatively independent divisions. Aircraft, Helicopters and Defence and Space.

The atmosphere is awesome, although not as awesome as the Dutch win on Friday, that was spectacular

Im Currently in german Highschool and what youre doing is like the exact Job Ive been dreaming of. What would you recommend me to do after ive finished school. Ive been thinking of studying aerospace engineering here in Germany, Berlin any other recommendations?

Uni Stuttgart, TU Munich, RWTH Aachen - in that order :)

What kinds of combustion behavior have you encountered that surprised you or were counterintuitive? For instance, have you ever set up a test and had one of those, "Wow, that's weird!" kind of moments?

No, something similar though when the exhaust is "engine-rich" and the wall disintegrates. That can produce beautiful colors

Thanks for the reply! Is engine rich another way of saying oxygen rich?

or fuel-rich?

Usually if a rocket engine is fuel rich the reaction gets limited by the amount of oxygen. However metal will burn spectacularly in the presence of high temps and excess oxygen. I've just never heard the term "engine rich" before.

I heard it a couple of weeks ago and I never get to use it

Hi and thanks for doing this AMA! I have always wondered do rocket engines have stuff in common with "normal" engines (the ones you see in cars) do they have similar parts or the same way of working?

Well, they have spark plugs. We use them to light the igniters for ground tested engines, but flying ones don't have any of the same parts you would expect

Do you think rocket power or some type of ballistic trajectory/rocket like technology will ever be used for day-to-day human transport?

At some point maybe, but it's way too expensive for now

Do you play kerbal space program?

Yes...a lot :)

This is exactly what I was hoping to go into, I love math and engineering.

What was your education prior to this? Ie: did you study much chemistry or was it mostly physics and calculus?

Do you play Kerbal Space Program?

It was mostly physics and calculus, the chemisty was voluntary and I chose to specialize a bit on it during my studies

I hope to be a rocket propulsion engine engineer soon! Start at Penn State this fall for engineering and then hopefully Aerospace Engineering in two years. Any advice to someone just starting school?

Enjoy life, but you have to get your shit together every now and then. Just make sure you know when and do it - no excuses

Sooo, what's the speed velocity if an airbus on slow motion?

No idea, I'm guessing around 100m/s