Definitely not a reaper if its flying at M1. The image shown is a Global Hawk which (according to wikipedia) does not fly near M1 speeds, but does have an operational ceiling of 60k ft. Might not be unmanned at all if it's on radar and being tracked.
Theoretically. But not likely. Air flow gets weird around the sound barrier. Each blade wound generate a sonic boom potentially damaging other blades. It’s just super impractical since we have jet turbines.
Never been done, but I think the prop driven Thunderscreech was designed (though never built) to go 1,000 mph, or mach 1.3. A Tupolev back in the 60s went 550 or so (about mach 0.7).
If you're asking "can you hit mach 1 for a brief period in a propeller airplane"? The answer there is "absolutely, just have fun crashing because the controls become weird". You can store energy in height, and then do a dive.
Sustained M1? Possible yes, practical, not really.
To make a long story short: "ideally" you want your engine to output an infinite amount of air at exactly your forward velocity (or near-infinite at just over your forward velocity). You have to kick back air at at least your forward velocity (otherwise you're not producing any net thrust at all). (Why? If you kick back air faster, you could be more efficient by kicking back more air, but slower.)
Now, obviously in practice you can't do that. There are compromises required - e.g. you can't really increase the size of an ungeared high-bypass turbofan as much as you'd like.
A standard propeller is designed for subsonic tip speed, and substantially subsonic flow as a result. You can build propellers for supersonic flow, but generally at that point it looks an awful lot like a turbine instead. (It's also loud, and tends to be rather inefficient due to adjacent blades interfering with each other.)
So all told, generally speaking you end up with propellers being great for relatively slow subsonic speeds (as they are slow, but can have a wide area), turbofans being good for higher speeds (they can have a higher exhaust velocity, but suffer from input area limitations due to materials issues), gradually shifting from high-bypass down to less and less bypass, and then true jets. (And then eventually ramjets and scramjets. A jet suffers from having to slow down the incoming air significantly, which hurts efficiency at higher speeds. Ramjets do too, but to a lesser extent. A scramjet doesn't nearly as much. Ramjets and scramjets have other issues, however. Notably, they tend to have terrible thrust-to-weight ratios.)
(A jet needs to slow down the incoming air to subsonic relative to the aircraft. So if you're moving at mach 3, a jet immediately does -2 mach numbers worth of "wasted" work that it then needs to overcome again. It's much more complex than this due to e.g. varying mach number with pressure and temperature, but that's the general gist of it. Kinetic energy being proportional to velocity-squared, if your scramjet is accelerating the air from mach 3 to mach 6 it's doing, say, 6^2-3^2 = 27 units of work, whereas a jet is taking air at mach 3, slowing it down to mach 1 (the energy of which is largely wasted. Not entirely, but largely.), and then having to accelerate that air to mach 6 again. So the jet is doing 6^2 - 1^2 = 35 units of work. As the speed increases, this becomes more and more of an issue.)
...though actually now that I look at it the accounts of hitting mach 1 in a dive are all "unverified" now. So you could probably argue that it hasn't been done.
Definitely not a reaper if its flying at M1. The image shown is a Global Hawk which (according to wikipedia) does not fly near M1 speeds, but does have an operational ceiling of 60k ft. Might not be unmanned at all if it's on radar and being tracked.
You seem to know planes. Is M1 possible without a jet engine, e.g prop, turboprop?
Theoretically. But not likely. Air flow gets weird around the sound barrier. Each blade wound generate a sonic boom potentially damaging other blades. It’s just super impractical since we have jet turbines.
I graduated in aerospace engineering a year ago. Still working on getting a job though.
Never been done, but I think the prop driven Thunderscreech was designed (though never built) to go 1,000 mph, or mach 1.3. A Tupolev back in the 60s went 550 or so (about mach 0.7).
1000 knots is about mach 1.5.
Never built that we know of. I bet the US military has had planes enter service and retire that we will never know about.
The only thing I know of that comes close,still flying today, is the Russian TU-95.
If you're asking "can you hit mach 1 for a brief period in a propeller airplane"? The answer there is "absolutely, just have fun crashing because the controls become weird". You can store energy in height, and then do a dive.
Sustained M1? Possible yes, practical, not really.
To make a long story short: "ideally" you want your engine to output an infinite amount of air at exactly your forward velocity (or near-infinite at just over your forward velocity). You have to kick back air at at least your forward velocity (otherwise you're not producing any net thrust at all). (Why? If you kick back air faster, you could be more efficient by kicking back more air, but slower.)
Now, obviously in practice you can't do that. There are compromises required - e.g. you can't really increase the size of an ungeared high-bypass turbofan as much as you'd like.
A standard propeller is designed for subsonic tip speed, and substantially subsonic flow as a result. You can build propellers for supersonic flow, but generally at that point it looks an awful lot like a turbine instead. (It's also loud, and tends to be rather inefficient due to adjacent blades interfering with each other.)
So all told, generally speaking you end up with propellers being great for relatively slow subsonic speeds (as they are slow, but can have a wide area), turbofans being good for higher speeds (they can have a higher exhaust velocity, but suffer from input area limitations due to materials issues), gradually shifting from high-bypass down to less and less bypass, and then true jets. (And then eventually ramjets and scramjets. A jet suffers from having to slow down the incoming air significantly, which hurts efficiency at higher speeds. Ramjets do too, but to a lesser extent. A scramjet doesn't nearly as much. Ramjets and scramjets have other issues, however. Notably, they tend to have terrible thrust-to-weight ratios.)
(A jet needs to slow down the incoming air to subsonic relative to the aircraft. So if you're moving at mach 3, a jet immediately does -2 mach numbers worth of "wasted" work that it then needs to overcome again. It's much more complex than this due to e.g. varying mach number with pressure and temperature, but that's the general gist of it. Kinetic energy being proportional to velocity-squared, if your scramjet is accelerating the air from mach 3 to mach 6 it's doing, say, 6^2-3^2 = 27 units of work, whereas a jet is taking air at mach 3, slowing it down to mach 1 (the energy of which is largely wasted. Not entirely, but largely.), and then having to accelerate that air to mach 6 again. So the jet is doing 6^2 - 1^2 = 35 units of work. As the speed increases, this becomes more and more of an issue.)
uhhhh
are you making shit up or where do you get your info from?
Personal knowledge gained in collage, mainly.
If you want more information, https://web.mit.edu/16.unified/www/FALL/thermodynamics/notes/node79.html is a decent starting point from a quick glance. Didn't see anything obviously wrong flipping through it quickly.
...though actually now that I look at it the accounts of hitting mach 1 in a dive are all "unverified" now. So you could probably argue that it hasn't been done.
Okay.