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Questions tagged [propulsion]

52 questions
15
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5 answers

Purpose of spheres and fins on submarine propeller

On a recently launched Russian diesel-electric submarine, the rear propeller has two distinct features. You can see spheres at the base of every propeller blade: Also, the trailing edge of the shaft has four adjoining fins in line with the axis of…
Rupert Reckless
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10
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Could air-launched space planes reach escape velocities?

Rockets like the Ariane 5 weigh hundreds of tons, but with about 85% of that weight being fuel, the payload fraction is only about 3% (~10-20 tons). Virgin Galactic is building suborbital space planes, mostly for tourism purposes. They fly at about…
NoDataDumpNoContribution
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9
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1 answer

Thrust distribution of engine

I am studying the thrust distribution of jet engines. But I'm now a bit confused. In Rolls-Royce's "The Jet Engine" book, http://aeromodelbasic.blogspot.com/2012/05/thrust-distribution-distribution-of.html At the start of the cycle, air is induced…
Jono
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7
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2 answers

Traction mechanisms for a robot in confined spaces

I'd like to build an exploratory robot that can fit within confined spaces1. What traction mechanisms should I consider to propel a robot along the inside of a 4" pipe? The pipe to be traversed will likely have fluid (assume water) within it to…
user16
5
votes
1 answer

Why don't propeller designers use multiple profiles?

I'm designing a ducted fan, and I'm deciding on the airfoil profile. NACA 16-series profiles are well-suited to M > .5 or .6, but they're not particularly efficient at lower Mach numbers. On the other hand, older profiles, like Clark YM, work quite…
user1493362
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2 answers

Why is high stagnation pressure important for propulsion?

In my propulsion notes I always see mention of the importance of minimizing stagnation pressure loss across the inlet shock of a ramjet/turbojet/turbofan. Could anyone explain further why this is the case, possibly with equations to explain certain…
InquisitiveInquirer
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4
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2 answers

Time-rate of change of P and T in a pressurized rigid volume with a hole in it

I am trying to model the time-rate of change of pressure and temperature of a gas being held within a pressurized rigid volume as it escapes: an unsteady, open system with no heat transfer. Most examples of an open system provided in-class and…
J. Day
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4
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2 answers

Why My Mini Boat Does Not Move Forward?

I am currently building a mini boat-like robot to clean the water from floating trash. I used two servo motors to move the loader that I have installed in front of the boat, and two 3 V DC motors installed in the back to allow the boat to move…
Ghadeer Aiydhah
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3 answers

Will this water jet propulsion system design produce any forward thrust?

I am interested in building a very basic water jet propulsion system for a toy boat. Before I build it, I would like to know from a conceptual standpoint if this design of a water jet propulsion system will actually produce forward thrust. Please…
user18610
3
votes
2 answers

Can you help me identify and explain this 1938 mechanical drawing of an "ambiverse gear"?

I'm looking for some help understanding this drawing from 1938. The title is "Ambiverse Gear," which gives a hint at what it might be. "Ambiverse" suggests bi-directional. Maybe an early differential of some kind? I believe this was an invention…
RickNZ
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3
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2 answers

Thrust on marine steam turbine casing

I attended a lecture today given by the steam turbine design expert Geoff Horseman. He discussed the turbine installations on ships such as the RMS Mauretania. Among other things, he remarked that an axial pressure gradient inside the turbine casing…
Theo H
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3
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2 answers

Compressing the air thrusted by an aircraft's propeller through a cone like tube

If I had an aircraft that used propellers for movement and took the air from the front running it through a tube that gets very small towards the end, would it have any impact on the speed? Would the aircraft get faster because the ejected air would…
Teslov Valentin
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1 answer

Development of an interstellar mission: should I design the propulsion system or the main hull of the ship first?

I am currently developing an interstellar mission for a school project. I am thinking whether to design the propulsion system (Bussard scoop) or the main hull and structure of the spaceship first. What do aerospace engineers begin with usually? I am…
MedwedianPresident
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Magnetic levitation

I am currently considering turning my fascination with magnets into a diy activity. How feasible is it for a hobbyist to construct a working model of a maglev device? I'm looking to build something really small for now,just a demonstrative…
Erata_jones
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1 answer

Valve for mini CO2 gas canister?

I am in the process of helping my son design a sort of model of the Bloodhound SSC car for his school project, using balsa wood, model aircraft wheels, etc... It doesn't have to a like of like, but vaguely resemblant so that you can tell what it is…
am304
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