Ramjet Flight in Jupiter's Atmosphere

Palomar · 2003-11-07 11:44:49

*Gets a bit on the technical side. Robert Dyck mentioned a ramjet in the "Voyager 1 Nearing the Heliosheath" thread.

Might provide some topic for discussion. I'll re-read it when I'm not working, and see if I can't throw a few questions or comments into the mix.

This is a really good web site; TJohn referred to Plus Ultra Technologies Inc. in a recent post ("Europa" thread). I like their motto, too: Ever Forward!

--Cindy

Palomar · 2003-11-26 14:03:53

*I re-read the article I linked to above.

They want to design the Ramjet to travel at 1.5 Mach speed, right? "The flyer incorporates a swept-wing configuration designed to fly at a nominal Mach number of 1.5"; but then there is also this (towards the end of the article): "the ramjet flyer will be exposed to the free stream conditions at Mach 1.5." Does this mean it will travel that fast *because of* the Jovian wind speed ("free stream conditions")?

However, the wind speeds on Jupiter are ferocious:

http://www.xs4all.nl/~carlkop/jupork.html

Averages 232 mph at the cloud tops, 293 mph seven miles down...etc...The article says the Ramjet would fly in the upper Jovian atmosphere; given the size of Jupiter, I'm wondering how deep "upper" is considered by Plus Ultra Techologies. Also, it seems the Ramjet is rather small; instruments in pods at the tip of each wing -- "located approximately 2 meters apart."

How do they expect the Ramjet can withstand these mega-hurricane-force conditions without simply being torn apart or battered around? Is it because of the speed the Ramjet itself can travel?

Maybe the answer is within the text, and I missed it where the article gets (what I consider) more technical. I'm curious.

--Cindy

RobertDyck · 2003-11-26 15:21:45

My dear, I am always willing to chat with you.

A parachute descending into the atmosphere will drift at the same speed as the wind as long as that wind is steady. Wind speed can be several times hurricane strength, but as long as it's steady the parachute will drift with it so that the relative speed is zero. You only have to worry about gusts. This article states the parachute will slow the capsule so it is falling at mach 1.5, then open to expose the aircraft. While inside the capsule the aircraft will not experience any wind, but once the capsule splits and falls away the aircraft will experience wind at the same speed it is falling. These guys are designing for a drogue chute rather than a normal parachute so that the airplane will fall at a speed high enough to start the ramjet engine. Any ramjet engine needs about mach 1 to start at minimum, so mach 1.5 is plenty safe.

The engine design sounds like the old Pluto intercontinental cruise missile, also known as SLAM. So what was a 1950's concept for a weapon of war is being converted to an exploration tool of peace. Cool.

One reason the ramjet can withstand rough conditions, is that a ramjet works by "ramming" the air in at supersonic speed. It doesn't have an air compressor or turbine. The only moving part on a conventional ramjet is the fuel injector. On a nuclear ramjet the only moving parts are the control rods. The control rods can be located around the outside of the engine, out of the air stream. The old Pluto was nick-named the flying crowbar; reliable because there isn't anything to go wrong. The only problem with Pluto was the radiation it spewed out in its exhaust. As a weapon of war, that was considered a bonus; after dropping all its bombs they would deliberately flying it back and forth over a target city. On Jupiter, that radiation will be like a teaspoon of water in the ocean compared to the radiation that is already in Jupiter's orbit or its core. Ack, I fear environmentalists will complain about contaminating Jupiter. But heavy radioactive waste will sink to the planet's core. And remember, Jupiter is big. I forget how many Earth size planets could fit within the great red spot alone.

But getting back to your question... The reason air speeds on Jupiter won't be a problem is that the aircraft has to endure air speed relative to aircraft speed.

Palomar · 2003-11-26 21:04:54

*Hi Robert. Thanks so much for answering.

I had no idea ("A parachute descending into the atmosphere will drift at the same speed as the wind as long as that wind is steady. Wind speed can be several times hurricane strength, but as long as it's steady the parachute will drift with it so that the relative speed is zero"). That's simply amazing.

You also wrote: "On Jupiter, that radiation will be like a teaspoon of water in the ocean compared to the radiation that is already in Jupiter's orbit or its core. Ack, I fear environmentalists will complain about contaminating Jupiter."

*Well, it'd be very petty of them to complain, based on the comparison you give.

Thanks again!

--Cindy

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#1 2003-11-07 11:44:49

Re: Ramjet Flight in Jupiter's Atmosphere

#2 2003-11-26 14:03:53

Re: Ramjet Flight in Jupiter's Atmosphere

#3 2003-11-26 15:21:45

Re: Ramjet Flight in Jupiter's Atmosphere

#4 2003-11-26 21:04:54

Re: Ramjet Flight in Jupiter's Atmosphere

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