Contrails and their formation

Cessnaflyer

Wooooooooooooooooooooooooooooooo
So I was sitting by the pool today looking at all the contrails being made over the GEG VOR. What had me wondering was that the contrails were looking like they were in pulses with clear spaces between them. If a jet is continuously making power (unlike a piston engine) why are there distinct pulses of condensation?

I tried to find a picture but most of them were linked to wacky chemtrail people.
 
So I was sitting by the pool today looking at all the contrails being made over the GEG VOR. What had me wondering was that the contrails were looking like they were in pulses with clear spaces between them. If a jet is continuously making power (unlike a piston engine) why are there distinct pulses of condensation?

I tried to find a picture but most of them were linked to wacky chemtrail people.

The atmosphere is ever changing my friend.
 
It was an inconsistent batch of chemgoo. We recently had our shipment recalled by the manufacturer. Actually, it wasn't so much a recall as some guys in black suits showing up in the wee hours of the morning and confiscating it from our hangar.
 
So I was sitting by the pool today looking at all the contrails being made over the GEG VOR. What had me wondering was that the contrails were looking like they were in pulses with clear spaces between them. If a jet is continuously making power (unlike a piston engine) why are there distinct pulses of condensation?

I tried to find a picture but most of them were linked to wacky chemtrail people.

It's probably due to shockwaves in the flow as it leaves the nozzle of the engine. Jet engines work by accelerating the air from the speed it has when it enters the engine to a faster airspeed. The force exerted on the airflow to bring about this acceleration means that there is an equal an opposite force exerted on the engine by the airflow (which is where the propulsive force comes from). Anyway, most of the time the airflow through the engine is accelerated to Mach 1 at the end of the nozzle, and then it accelerates even faster as the flow expands leaving the nozzle. So the airflow is going faster than Mach 1, and it can have shockwaves in it. Across these shockwaves the temperature and pressure changes pretty significantly. It's been 11 years since I've studied any aerodynamics, though, but I think that's what is causing it.
 
It's probably due to shockwaves in the flow as it leaves the nozzle of the engine. Jet engines work by accelerating the air from the speed it has when it enters the engine to a faster airspeed. The force exerted on the airflow to bring about this acceleration means that there is an equal an opposite force exerted on the engine by the airflow (which is where the propulsive force comes from). Anyway, most of the time the airflow through the engine is accelerated to Mach 1 at the end of the nozzle, and then it accelerates even faster as the flow expands leaving the nozzle. So the airflow is going faster than Mach 1, and it can have shockwaves in it. Across these shockwaves the temperature and pressure changes pretty significantly. It's been 11 years since I've studied any aerodynamics, though, but I think that's what is causing it.

Nope. Its a bad batch of chemgoo. Trust me.
 
It's probably due to shockwaves in the flow as it leaves the nozzle of the engine. Jet engines work by accelerating the air from the speed it has when it enters the engine to a faster airspeed. The force exerted on the airflow to bring about this acceleration means that there is an equal an opposite force exerted on the engine by the airflow (which is where the propulsive force comes from). Anyway, most of the time the airflow through the engine is accelerated to Mach 1 at the end of the nozzle, and then it accelerates even faster as the flow expands leaving the nozzle. So the airflow is going faster than Mach 1, and it can have shockwaves in it. Across these shockwaves the temperature and pressure changes pretty significantly. It's been 11 years since I've studied any aerodynamics, though, but I think that's what is causing it.

Thanks that makes more sense.

I just thought of a better description of how it looked. It was almost like an old steam train with the puffs of smoke and then spaces in between.
 
Thanks that makes more sense.

I just thought of a better description of how it looked. It was almost like an old steam train with the puffs of smoke and then spaces in between.

I think this is what you are talking about.
 

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Completely off-topic... are you a CFI at Geiger Field? I am a private pilot (in the military stationed at Fairchild, quite far from my home airport in Iowa) looking into getting involved with Spokane Airways for my instrument rating. Do you have any suggestions? Are they a good school?

Thanks!
 
Completely off-topic... are you a CFI at Geiger Field? I am a private pilot (in the military stationed at Fairchild, quite far from my home airport in Iowa) looking into getting involved with Spokane Airways for my instrument rating. Do you have any suggestions? Are they a good school?

Thanks!

Sorry for the late reply, I've been away from jetcareers for a bit.

I teach at Spokane Airways and I love it here By far one of the best FBOs in the state. I do instrument instructing and we use a Cessna 172RG with a Garmin 430. If you have any more questions you can pm me or call 509-747-2017
 
I really didn't see the contrail or even the science he used to determine that it was traveling 8,000 MPH! ;)
 
isn't the YF-12A at Wright Patterson?

Yes. I was there a few years ago and noticed the cheek chines first. I stepped into the nose gear well and noticed a large tank which housed liquid nitrogen. ??? I later learned that tank was rreportedly used to cool the head of the AIM-47 Falcon missiles. ( according to some sources, the -47 was scaled up to make the -54 Phoenix later carried by the F-14)

This is a bit of a read but it covers the YF-12 pretty well.
http://www.wvi.com/~sr71webmaster/yf12~1.htm


This page says the progression was A-11 to YF-12 to SR-71.
http://www.unrealaircraft.com/gravity/sr71.php
 
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