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How do you power a rocket engine?

everydayastronaut.com

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Re: How do you power a rocket engine?

#71

Post by mhio »

phkahler wrote: post #57
panick21_ wrote: post #46

Earlier quoted context omitted.

Yes. See: https://en.wikipedia.org/wiki/SABRE_(rocket_engine) https://en.wikipedia.org/wiki/Skylon_(spacecraft) But there are lot of problems with this and it adds a huge amount of complexity.

Maybe too small an effect, but what if they put 8 NACA scoops on the sides of Falcon 9 and just fed the air in between the center and outer engines. It would get accelerated out with all the regular exhaust, and I suppose would cause a small back pressure on the center engine in particular, but they could throttle it slightly if that were a problem.

How would feeding air outside of an engine increase performance?

Unless the gas is accelerated inside the engine bell, I don't see a force being applied to the rocket.

Re: How do you power a rocket engine?

#72

Post by chipsa »

Robotbeat wrote: post #43
showerst wrote: post #17

Earlier quoted context omitted.

I’m really torn on Integza. It’s a great channel and I love his spirit, but guys like that (and the teenagers that follow them) end up getting hurt or burning down their houses, which makes the news and gets new restrictions passed on all of us. Just a _little_ more nodding to safety would make him an awesome resource. Maybe safety culture in Portugal is different, but in the US he does tons of stuff that violates th…

I wouldn’t consider the rocketry code itself a good argument. The model rocketry code, frankly, is biased hard against any kind of liquid (especially non-hybrid) rocket engines, so there’s not even really a way he could follow it with a liquid in any reasonable way. (Which isn’t to say he couldn’t follow better safety common sense.)

The model rocketry code is for model rockets, not high power amateur rocketry. Though the HPR safety code also isn't friendly to liquids, but partly because it still dictates commercially developed motors.

Re: How do you power a rocket engine?

#73

Post by db48x »

McLaren_Ferrari wrote: post #50
Stratoscope wrote: post #48

Earlier quoted context omitted.

You're off by a decade. Garmin introduced their StreetPilot in 1998. I didn't buy the first model, but when the StreetPilot III came out in early 2002 I jumped on it. That GPS served me well for many years. Sure, GPS wasn't ubiquitous like it is today where everyone has one in their pocket, but it certainly was available to the general public.

> Garmin introduced their StreetPilot in 1998. I didn't buy the first model, but when the StreetPilot III came out in early 2002 I jumped on it. That GPS served me well for many years. https://www.cnet.com/roadshow/reviews/garmin-street-pilot-ii... "the manufacturer lists $1,272" 1,272$ in 2002 = 2120$ in 2022. This is what people mean when they say techno-utopianists, space fans and SV types are completely detached…

Clearly nobody benefited when when truck and taxi drivers started buying these. There were no benefits to society at all when every rental car came with a GPS system or when new cars started shipping with built–in navigation systems. None of those improve anyone’s quality of life, which is all that counts.

Re: How do you power a rocket engine?

#74

Post by cubefox »

panick21_ wrote: post #21
cubefox wrote: post #12

Earlier quoted context omitted.

Regarding the first point, I'm not sure whether aerospike engines can still be considered heat limited. Even in the 90s with the X-33 aerospike spacecraft, heat was not cited as the reason for cancellation. And nowadays material science as progressed by a lot, which resulted in more heat resistant materials, e.g. this one: https://www.nasa.gov/feature/glenn/2022/nasa-s-new-material-...

Maybe I wrote it wrong. Closed expander cycles are heat limited. Areospike require more cooling then traditional bell designs. So an areospike epxnader cycle could produce more thurst. See here for some research: https://www.phoenix-int.com/wp-content/uploads/2017/05/Param...

Now I understand, thanks.

Re: How do you power a rocket engine?

#75

Post by Stratoscope »

McLaren_Ferrari wrote: post #50
Stratoscope wrote: post #48

Earlier quoted context omitted.

You're off by a decade. Garmin introduced their StreetPilot in 1998. I didn't buy the first model, but when the StreetPilot III came out in early 2002 I jumped on it. That GPS served me well for many years. Sure, GPS wasn't ubiquitous like it is today where everyone has one in their pocket, but it certainly was available to the general public.

> Garmin introduced their StreetPilot in 1998. I didn't buy the first model, but when the StreetPilot III came out in early 2002 I jumped on it. That GPS served me well for many years. https://www.cnet.com/roadshow/reviews/garmin-street-pilot-ii... "the manufacturer lists $1,272" 1,272$ in 2002 = 2120$ in 2022. This is what people mean when they say techno-utopianists, space fans and SV types are completely detached…

So I bought the deluxe model. I happened to find my original purchase in Moneydance (a quick search for "gps" did it) and I paid $834.99 with tax and shipping.

I don't see why that puts me in a world of fairy tales and unicorns. I wasn't rich, I just saw the value and chose to buy it. It was a small fraction of what I paid for my car, after all.

Perhaps more to the point, the original StreetPilot from 1998 had a list price of $400.

Re: How do you power a rocket engine?

#76

Post by addaon »

mhio wrote: post #71
phkahler wrote: post #57

Earlier quoted context omitted.

Maybe too small an effect, but what if they put 8 NACA scoops on the sides of Falcon 9 and just fed the air in between the center and outer engines. It would get accelerated out with all the regular exhaust, and I suppose would cause a small back pressure on the center engine in particular, but they could throttle it slightly if that were a problem.

How would feeding air outside of an engine increase performance? Unless the gas is accelerated inside the engine bell, I don't see a force being applied to the rocket.

This approach is often called a thrust augmentor, e.g. https://doi.org/10.1023/B:FLUI.0000045678.92653.98. Basically you're using excess energy in a high-speed jet exhaust to accelerate ambient air, increasing the total momentum at a lower exhaust speed.

Re: How do you power a rocket engine?

#77

Post by panick21_ »

WalterBright wrote: post #70
panick21_ wrote: post #68

Earlier quoted context omitted.

> The Saturn V engines were scaled up V2 engines. I mean, not really. They were a totally different cycle type. Different fuel. Different way adjusting trajectory. Different injectors. Seems pretty different to me.

Different cycle type? I'm interested - what's different?

I mean one uses the main propellant to drive the turbine the other has a sodium permanganate/hydrogen peroxide. That seems to me a pretty significant difference in how the engine works.

To be fair, technically one could call both gas generators but its still significantly different.

Re: How do you power a rocket engine?

#78

Post by McLaren_Ferrari »

db48x wrote: post #73
McLaren_Ferrari wrote: post #50

Earlier quoted context omitted.

> Garmin introduced their StreetPilot in 1998. I didn't buy the first model, but when the StreetPilot III came out in early 2002 I jumped on it. That GPS served me well for many years. https://www.cnet.com/roadshow/reviews/garmin-street-pilot-ii... "the manufacturer lists $1,272" 1,272$ in 2002 = 2120$ in 2022. This is what people mean when they say techno-utopianists, space fans and SV types are completely detached…

Clearly nobody benefited when when truck and taxi drivers started buying these. There were no benefits to society at all when every rental car came with a GPS system or when new cars started shipping with built–in navigation systems. None of those improve anyone’s quality of life, which is all that counts.

Oh cmon. The money of regular taxpayers was the first in and the quality of life for them was the last out.

The investment only started paying real dividends in terms of generalized quality of life in the 2010s.

You want to say it was 35 years and not 40? Fine. If you are a guy who was in his 50/60 back in the 1970s then 40-35-30 or even if I give you 20 years if you consider that the investment totally repaid itself when the early adopters started buying GPS (which is a very bad way to calculate it )....it's all the same. You didn't see improvements in your quality of life because given life expectancy back then chances are you'd not be having a life at all (and this includes when the very early adopters bought it)

Re: How do you power a rocket engine?

#79

Post by db48x »

McLaren_Ferrari wrote: post #78
db48x wrote: post #73

Earlier quoted context omitted.

Clearly nobody benefited when when truck and taxi drivers started buying these. There were no benefits to society at all when every rental car came with a GPS system or when new cars started shipping with built–in navigation systems. None of those improve anyone’s quality of life, which is all that counts.

Oh cmon. The money of regular taxpayers was the first in and the quality of life for them was the last out. The investment only started paying real dividends in terms of generalized quality of life in the 2010s. You want to say it was 35 years and not 40? Fine. If you are a guy who was in his 50/60 back in the 1970s then 40-35-30 or even if I give you 20 years if you consider that the investment totally repaid itself…

So a bridge that takes 5 years to build is a scam because the 90–year–olds won’t live to see it built? That’s overly reductionist. In your way of thinking the rewards must be instantly available in order to be worth anything. I say that humanity needs more long–term projects, not more short–term consumerism.

Re: How do you power a rocket engine?

#80

Post by McLaren_Ferrari »

db48x wrote: post #79
McLaren_Ferrari wrote: post #78

Earlier quoted context omitted.

Oh cmon. The money of regular taxpayers was the first in and the quality of life for them was the last out. The investment only started paying real dividends in terms of generalized quality of life in the 2010s. You want to say it was 35 years and not 40? Fine. If you are a guy who was in his 50/60 back in the 1970s then 40-35-30 or even if I give you 20 years if you consider that the investment totally repaid itself…

So a bridge that takes 5 years to build is a scam because the 90–year–olds won’t live to see it built? That’s overly reductionist. In your way of thinking the rewards must be instantly available in order to be worth anything. I say that humanity needs more long–term projects, not more short–term consumerism.

> I say that humanity needs more long–term projects, not more short–term consumerism.

Right. If this is so crystal clear then you'd not have any problems finding people who'd put up their own money instead of extorting them.

Crystal clear + you'd have to convince a bunch 90 year olds it should not be too hard...then everybody is happy. Even scammers have the decency to convince old people to give them their money as opposed to extorting them under the threat of violence .

For sure when I am 90 I'd do everything in my power to avoid being sucked into paying for stuff that I'll never get to see or use. Old people are not jailed for tax evasion, even today...so I guess unless something changes if I get to that ripe age it would be the same.

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