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1500 questions
6
votes
2 answers
Why afterburners are needed instead of burning more fuel inside the turbine?
I'm reading this article on afterburners:
https://www.airspacemag.com/flight-today/how-things-work-afterburners-18481403/
It says in the article:
A typical jet engine uses only about half the oxygen it ingests, leaving a large amount of potential…
S. Rotos
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6
votes
6 answers
Why are turbo compound engines not more widely used?
Turbo compound engines extract some exhaust energy by using it to power a turbine connected to the driveshaft. Why are these engines not more widely used?
Brinn Belyea
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6
votes
3 answers
How can I keep a Zippo lighter from losing fluid to evaporation or leaks?
Zippo lighters are notorious for needing regular refilling. The fuel evaporates from the cotton regularly.
Some people put a bit of rubber around the seal.
What atmospheric conditions keep fuel from evaporating? Temperature, humidity, etc.
Should I…
Mohammad Athar
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6
votes
2 answers
Is there a way to reduce leaks and infrastructure damage when turning water on and off at the scale of city?
Cape Town, South Africa is experiencing an extremely serious drought, with estimates putting April 21, 2018 as the day that the city will be forced to shut off all municipal water supplies and begin water rationing, except to essential services such…
Jonathan Rayner
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6
votes
7 answers
How would you move a sail boat with no wind or paddles
If I stood on a sailing ship and had a very strong pair of lungs (possibly motorized) then if I blew the sail would I be able to move the ship forwards?
Owensteam
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6
votes
1 answer
Do outer fillets|chamfers also reduce stress as inner ones do?
I kind of have an intuition or at least imagination about how fillet|chamfer of inner edges|vertexes reduce stress (concentration).
But does that apply to outer edges|vertexes aswell? Maybe to a lesser degree or not at all?
So should one use outer…
hepe
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6
votes
4 answers
Why are Whitworth threads angled at 55°?
You're probably thinking, "Well.. Why not? It's gotta be something.." Right?
But 55° is kind of an odd angle if you think about it.. and it does seem like a pretty specific choice considering a perfect equilateral/equiangular triangle consists of…
voices
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6
votes
3 answers
Buoyancy force problem
I'm trying to design a kind of water valve with inexpensive materials as a first prototype.
The water flow from the PVC pipe (1) reach the body of the valve and pass through an aluminum grid (3) to the water tank. When the water level goes up…
Joaquin Osses
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6
votes
1 answer
Is the tolerance of pitch of a thread standarized?
As I was browsing ISO 965-1 it defines tolerances on a plenty of variables regarding metric threads, but it gives the pitch of the thread as a simple number from an allowed set ( 3 – 2 – 1,5 – 1– 0,75 – 0,5 – 0,35 – 0,25 – 0,2 ), and no tolerances…
SF.
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6
votes
2 answers
Could adding extra engines to AMELIA disrupt airflow from the other engines?
AMELIA is the product of a partnership between NASA and the California Polytechnic State University. One of its innovations is circulation control. An engine is mounted over each wing, and high pressure air is redirected from the exhaust over the…
HDE 226868
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6
votes
5 answers
Why do electric cars claim "instant torque?"
I was at a well-known electric car company today and they claimed "instant torque." The quote was something like the following:
Driving this car is very different from a gas-powered vehicle. For example, it has instant torque when you press the…
Mowzer
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6
votes
1 answer
What is the process for qualifying a weld between structural steel and stainless steel?
In the US, typical structural steel welding is covered by either AWS D1.1 or AWS D1.5 (bridges). Both of these codes cover a wide range of carbon steels.
AWS has a separate code for welding stainless steels, AWS D1.6. There is some mention of…
hazzey
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6
votes
1 answer
Do regulations in the United States limit the size of aerial wind turbines?
What with all the work done by the FAA recently on regulating drone usage, I thought it would be nice to turn my eyes to the sky for another, less-known type of aerial denizen: the aerial wind turbine.
Wikipedia has all the relevant information, so…
HDE 226868
- 2,475
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- 34
6
votes
4 answers
Is radians a dimensionless quantity?
Quite often while calculating angular velocity we come across the quantity radians per second. How do I treat radian dimensionally?
Rajorshi Koyal
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6
votes
3 answers
O-Ring vs flat washer for air seal
I'm interested in whether a flat rubber washer or equivalent is good enough to replace an o-ring in a low pressure application (edit: I meant low pressure differential. My bad.). The reason is that flat washers might be easier to design for if you…
carveone
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