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Questions tagged [propulsion]

49 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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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…
Trilarion
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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
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
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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1 answer

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…
Ibrahim
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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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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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2
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Sizing electric motor

I've been looking for a way to size an electric motor for a vehicle that could be assumed as a box-shaped load with a mass of 60 kg, up a 10° incline, at 1.6 m/s, using continuous tracks with 1 motor per side, but for some reason while searching for…
Calpurnius Kazik
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2
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Could boiling water inside a semi-enclosed pipe be a low-cost method for a silent marine propulsion system? (redesigned)

I am wondering if boiling water that is trapped inside of a semi-enclosed pipe would be a low-cost method of creating an underwater thruster that would function as a silent marine propulsion system. Please reference the following conceptual…
user57467
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