Linked Questions

31
votes
7answers
7k views

Why are jet aircraft never designed with a slower cruise speed?

All jet airliners have a cruise speed between Mach 0.82 and Mach 0.85. At those speeds the aircraft are flying at their maximum subsonic speed. Any greater cruise speed would only be ...
22
votes
3answers
11k views

Why are propeller engines uncommon on airliners?

My experience in aviation is essentially zero, but looking at Wikipedia it seems like the Tu-95 Bear offers high subsonic speed and extreme range. I assume that turboprop engines are more fuel ...
18
votes
2answers
7k views

How is supercruise achieved?

Wikipedia article tells that supercruise is a condition when an aircraft can achieve velocities above Mach one without using the highly inefficient afterburners. But still, there are not a lot of ...
8
votes
3answers
9k views

How is combustion flame maintained in the combustion chamber after igniters are switched off?

During start phase of a jet engine, igniters in the combustion chamber create sparks to initiate combustion. As far I know, when the engine reaches self sustaining speed, igniters get turned off (...
11
votes
2answers
4k views

Why is max endurance different for jet and props?

Max endurance speed is not the same for gliders, propeller planes (also for turbo prop, right?) and jet planes. While for for jet planes max endurance is at the minimum drag speed ($V_{md}$), for ...
3
votes
3answers
3k views

Why are the top speeds for jet engines higher than for propellers?

I realize turbines are more efficient than piston engines, but if that were true, then why don't turbo-props reach jet speeds?
15
votes
3answers
406 views

Acceleration of a supersonic aircraft after breaking the sound barrier

People on the physics stackexchange recommended I ask here, so I am pasting my question regarding supersonic aircraft. I stumbled upon an interesting plot; in particular, the dependence of wave drag ...
-2
votes
1answer
4k views

Why don't airliners have turboprop engines instead of jet engines? [duplicate]

I know the q400 is one of few airliners that has a turboprop engines. I know that some military airplanes use turboprop engines so why don't many airliners use them?
12
votes
1answer
909 views

Why is the combustor volume of a jet engine decided by altitude?

I have read that the combustor volume of a jet engine is decided by the maximum altitude up to which that aircraft will fly. I'm getting confused by that, because the maximum mass flow rate will occur ...
1
vote
1answer
997 views

Why is the ratio of TSFC at altitude vs. sea level different for hi-bypass vs. lo-bypass turbofan engines?

I've read up on how the thrust-specific fuel consumption of turbofan/turbine engines increases with altitude, and the Georgia Institute of Technology plot in particular seems to indicate that, for ...
3
votes
1answer
470 views

How does a wing mounted jet engine on a supersonic airplane prevent the interference in the flow due to Shock? [duplicate]

Wing mounted jet engines face the free stream at Mach number 1 or above, and they work perfectly for Mach numbers below 1 as well, even though the free stream characteristics change a lot after Mach 1....
5
votes
1answer
439 views

Could Mach 1.4 be a better design point for SST?

There's been a number of recent proposals for design work on low-supersonic bizjets that would cruise at Mach 1.1-1.6, the common theme being avoiding a sonic boom. I'm wondering if this range of ...
0
votes
0answers
170 views

How does supercruise thrust compare with static thrust ASL?

As I understand it, turbojet thrust decreases both with altitude due to rarefied air reducing massflow, and airspeed due to a smaller speed increase between intake and exhaust relative to the airframe....