If you can read this, either the style sheet didn't load or you have an older browser that doesn't support style sheets. Try clearing your browser cache and refreshing the page.

(Some Guy)   Cool picture of a contrail created by USAF's new pulsed engine detonation   (fas.org) divider line 50
    More: Cool  
•       •       •

5828 clicks; posted to Geek » on 04 Jan 2007 at 2:34 AM (7 years ago)   |  Favorite    |   share:  Share on Twitter share via Email Share on Facebook   more»



50 Comments   (+0 »)
   

Archived thread
 
2007-01-03 11:28:16 PM
Aren't they supposed to be so loud they qualify as a sonic weapon?
 
2007-01-03 11:45:35 PM
Another overpriced under performing prototype?
 
2007-01-03 11:48:20 PM
You cant hear it. One flies over Sacramento and Dixon almost weekly. It's incredibly fast at extreme high altitudes, (so high the plane is not visible.) It absolutely streaks across the sky compared to the other jets that we get around here. I've tried calling my brother who lives in Marysville about 80 miles north, and by the time he gets outside its gone.
 
2007-01-03 11:59:22 PM
That's swamp gas.


/Move along...
 
2007-01-04 12:10:29 AM
Or a weather balloon. Moving really, really, really fast.

/Nothing to see here....
 
2007-01-04 12:59:08 AM
lionfish: I've tried calling my brother who lives in Marysville about 80 miles north, and by the time he gets outside its gone.

Ahh, the megalopolis that is Marysville and Yuba City. Grass Valley had a couple of cool coffee shops in the mid 90's, though!

/Beale
//Pave Paws
 
2007-01-04 01:17:00 AM
I wonder if you could redo the filters on a radar unit to accept signals from a Mach 4+ aircraft. The Doppler shift would be really high and hard to miss if you where looking for it. The Russians tracked the SR-71 easily so I guess it would be possible to do, though anti-radar materials would make it difficult.

That or have a high speed infared camera. I don't care what kind of stealth you have. Anything at Mach 4+ is gona be HOT, even at the high altitures this thing supposedly travels at.
 
2007-01-04 02:00:01 AM
Crosshair

Okay I'm gunna bite and probably look stupid...

Since radar is based on sound and the plane is traveling faster than sound wouldn't it be impossible to locate with radar. You'd know where it was, and I suppose could extrapolate where it might be, based on its speed and trajectory, but if it altered course, even a little bit, you wouldn't be able to hit it.
 
2007-01-04 02:41:44 AM
jingks

No. Radar, which stands for Radio Detection And Ranging, uses radio waves that are bounced off a target to find it. And since all electromagnetic energy travels at the same rate (3.0 x 10^8 m/s) it would have to travel faster than light to be avoided.

On a side note, any slower object can intersect a faster one, provided that both objects are approaching each other. It would be a matter of calculating the travel times (as in the "train a leaves city 1 at 4:00, and train b leaves city 2 at 4:30..." math problem)
 
2007-01-04 02:44:01 AM
jingks [TotallyFarkingStoopid]

Okay I'm gunna bite and probably look stupid...


Yes. You are.


Since radar is based on sound and the plane is traveling faster than sound wouldn't it be impossible to locate with radar. You'd know where it was, and I suppose could extrapolate where it might be, based on its speed and trajectory, but if it altered course, even a little bit, you wouldn't be able to hit it.


Okay. This is why we shouldn't let idiots logon to the internet.

RADAR IS NOT BASED ON SOUND

Please logoff, cancel your AOL subscription, and don't post on the internet again until you can figure out what radar is based on.

Honestly, this is middle-of-last-century technology. You can't possibly have graduated high school without knowing about radar. There's no excuse.
 
2007-01-04 02:48:05 AM
grandjedimasterbill

See, I told you I was going to look dumb. Yeah, of course, I suppose the old brain took a nap. When I read radar, the mental image of a submarines sounder(?) in my head.

On a side note, any slower object can intersect a faster one, provided that both objects are approaching each other.

Yeah, but I was assuming the intercepter couldn't change course.

/ stop picking on me... geez
 
2007-01-04 03:01:25 AM
My turn to look dumb. I haven't heard of this kind of engine. Could someone post a link or explain, please.

/And be easy on me, I honestly just want to learn.
 
2007-01-04 03:06:22 AM
Wow chaotey, way to be pleasant!

Anyways jingks, sonar is what is based off of sound. It's what they use to detect stuff through water.
 
2007-01-04 03:20:04 AM
These have been reported and denied over the Scottish North Sea for at least 20 years. Always ascribed to Aurora - Airfix even had a model of it, at one point, just before they went bank+++ no carrier +++
 
2007-01-04 03:23:44 AM
I would assume that while any force with half+1 good detection would be able to pick up and even track a mach 4+ craft they would have the same problem the russians had with the blackbird... it was so high and so fast they didn't have a weapon that could hit it. (later on, I hear they could have hit it, but didn't want to for fear of reprisal)
To use the "slower as long as both approaching" thing you'd have to launch your weapon x-many miles in front of the craft, give it time to get x-many feet high (since the PWDE planes fly very very high) and still you're trying to intercept a small object at a very high rate of cross-speed.
It's possible, but very very hard.
 
2007-01-04 03:35:57 AM
jingks: Since radar is based on sound

I've just learned something. Drinking + reading stupid statements makes my head hurt. :)
 
2007-01-04 03:43:30 AM
umm.....I've seen regular jet contrails do this as they dissapate. There's no evidence in that picture it's due to a pulsed engine detonation. Pretty sure they wouldn't operate it during the day anyway if it even does exist in a functioning aircraft - how many years were the Blackbird, F-117 and B-2 in existence before they took their first daytime flights?
 
2007-01-04 03:45:33 AM
jingks: See, I told you I was going to look dumb. Yeah, of course, I suppose the old brain took a nap. When I read radar, the mental image of a submarines sounder(?) in my head.

thats sonar, which stands for SOund Navigation And Ranging, you were right thatit uses sound, but Sonar is used underwater because radio waves are absorbed very quickly in water. the sonar systems are so sensitive that the cookware in the galley is specially coated to prevent noise.

cool experiment, take your walkman and jump into the pool, try turning it on. it won't work, know why? the water absorbs the radio waves!

so you were right about subs using sound, just applying to aircraft incorrectly. they use radiowaves to range, and radiowaves travel at the speed of light like chaotey so politely put it, so the aircraft would have to be traveling faster than light to escape its reach (it would actually take more energy in existance to propel one atom to the speed of light, thats why it's kind of impossible)

chaotey, sand doesn't usually make someone so biatchy, do you have polonium in your vagina?
 
2007-01-04 03:48:56 AM
And since all electromagnetic energy travels at the same rate (3.0 x 10^8 m/s)

That's not true.

On a side note, any slower object can intersect a faster one, provided that both objects are approaching each other.

Not accurate. Any slower object can intersect a faster one, provided that both objects are approaching each other on the same vector.

\if you're trying to talk smart, be good at it
\\slashies
 
2007-01-04 04:01:00 AM
I have a better experiment: Plug in your toaster, jump into your bathtub, try to listen to it underwater! Joila!

/may cause side effects not listed on the label
 
2007-01-04 06:34:46 AM
Stump654: I've seen regular jet contrails do this as they dissapate. There's no evidence in that picture it's due to a pulsed engine detonation. Pretty sure they wouldn't operate it during the day anyway if it even does exist in a functioning aircraft - how many years were the Blackbird, F-117 and B-2 in existence before they took their first daytime flights?

Agreed...

/these are not the contrails you're looking for
 
2007-01-04 06:57:08 AM
Big Brother: cool experiment, take your walkman and jump into the pool, try turning it on. it won't work, know why?


Because they don't work in water.


The SR71 was a fast plane for it's time. The DoD would have created something more advanced by now.
 
2007-01-04 08:03:46 AM
re: the Mach-4-can't-be-tracked-on-radar ninnies. You know that ICBMs travel a lot faster than that, don't you? And we track those. My back of the envelope calculation: the EM doppler shift of a Mach-4 device (approx 3200 mph, 4800 kph) is something like 5 parts per million. Not exactly a problem.
 
2007-01-04 08:12:25 AM
not new

this looks like the Aurora project from about 8 years ago

people were seeing weird donuts in the sky, thought it was aliens

i even saw a home video some guy took... wonder if i can find that now...

/look for follow-up later today
 
2007-01-04 08:20:54 AM
found it!

link is halfway down, requires realplayer

Aurora

/don't be fooled by the picture of the SR-71
//doesn't pop
 
2007-01-04 09:07:10 AM
Stump654: how many years were the Blackbird, F-117 and B-2 in existence before they took their first daytime flights?

You are forgetting who is in charge now. They really don't care who knows what. Maybe they found a need to show off their new toy.
 
2007-01-04 09:13:49 AM
SirFire: Any slower object can intersect a faster one, provided that both objects are approaching each other on the same vector.

\if you're trying to talk smart, be good at it


One vector can intersect itself? Did I miss something in 9th grade trigonometry?

/take your own advice
//your slashies are backwards
 
2007-01-04 09:17:24 AM
So how long before they actually admit that they have a working engine, as far as i can remember they always denied this thing as a myth and said it was too hard to make.
 
2007-01-04 09:25:54 AM
Maybe it's just an engine with really bad compressor surge?



FrancoFile: re: the Mach-4-can't-be-tracked-on-radar ninnies. You know that ICBMs travel a lot faster than that, don't you? And we track those. My back of the envelope calculation: the EM doppler shift of a Mach-4 device (approx 3200 mph, 4800 kph) is something like 5 parts per million. Not exactly a problem.

Well, if you read his post a bit more closely, you'll see he said something about adjusting the filters to allow it to be indicated. A lot of radar uses range gates and Doppler filtering to remove false returns. If you don't look like a target it's meant to display, you may not show up.

It's moot, though, because the putative airframe uses a system that returns a misleading Doppler. But I digress.
 
2007-01-04 09:26:33 AM
According to Wiki, a pulse detonation engine pulses around 250 times per second. Even at Mach4+ speeds, you probably wouldn't have 'donuts' spaced so far apart.

These same types of contrails have been photographed - in the day time - for years.

Chances are this pic is not of the PDE.
 
2007-01-04 09:29:32 AM
To those who have the 'interesting' belief that it is difficult to track an object traveling Mach 4+ with radar, heres something interesting to note. Radaar uses radio signals that travel at or near the speed of light. so heres a quick calculation to demonstrate my point.

Very Near the Speed of light >>>>>>>>>>>>> Mach 4+

that should help clear things up a bit, lol

/don't mean to sound snippy..
//find it hard to believe that some people know little about a 60+ year old technology, yet still are able to use the intarwebs..
 
2007-01-04 09:33:44 AM
Superman picked up a smoking habit
 
2007-01-04 09:36:19 AM
Evil Batman: /don't mean to sound snippy..
//find it hard to believe that some people know little about a 60+ year old technology, yet still are able to use the intarwebs..


Perhaps before you get too snippy, you'll have a nice read on radar countermeasures that work by farking with display filtering algorithms.
 
2007-01-04 09:39:28 AM
bookelly: My turn to look dumb. I haven't heard of this kind of engine. Could someone post a link or explain, please.

Supposedly an engine than runs on repeated explosions that are channeled in one direction and the "donuts-on-a-rope" contrails would be the telltale signs of the repeated explosions. Wiki.

According to some, the mythical Aurora aircraft would have used this propulsion mechanism.

I've seen regular Airbuses and Boeings do these types of contrails, so unless major non-US-based airlines are US DoD front companies testing classified engines on regular flights, I'll be joining stump654 and damitjim in my skepticism.
 
2007-01-04 09:56:55 AM
Pulsed detonation engines just sound like a fancy version of a V1 Doodlebug :P Ok so V1s dont run at 250Hz...But c'mon, USAF could at least come up with their own tech, rather than stealing it from Nazi Germany...
 
2007-01-04 10:01:05 AM
SirFire:
On a side note, any slower object can intersect a faster one, provided that both objects are approaching each other.

Not accurate. Any slower object can intersect a faster one, provided that both objects are approaching each other on the same vector.

\if you're trying to talk smart, be good at it
\\slashies




Take your own advice. It doesnt have to approach on the same vector. It can intersect and be traveling a different vector. The vector itself doesnt matter, its the intersection that counts.
 
2007-01-04 10:04:03 AM
null/void: Pulsed detonation engines just sound like a fancy version of a V1 Doodlebug

PDWE is only superficially similar to a pulse-jet.

Here is a PDF that sort of brushes across the surface of it. He's even mostly right.

Do yourself a favor and skip the crap you find on ATS, Rense and the like, there are some really informative refereed articles on PDWE to be had, if you're interested in poking about the net for them.

They have a very distinctive sound, too, and you can occasionally see letters to the editor in a certain Midwestern area biatching about the weird noises coming from a certain AFB.
 
2007-01-04 10:12:55 AM
haterade: I have a better experiment: Plug in your toaster, jump into your bathtub, try to listen to it underwater! Joila!

You realize that someone might actually do this?

And they'll have the toaster plugged into a phone jack.
 
2007-01-04 10:43:30 AM
*backs away slowly*
 
2007-01-04 11:35:21 AM
chaotey
Okay. This is why we shouldn't let idiots logon to the internet.


And you're why we shouldn't let insecure, unpleasant asswipes log on to the internet.
 
2007-01-04 12:19:18 PM
Shenanigans

The "donut on a rope" contrail has been witnessed by hundreds of pilots, civilians and aviations enthusiasts. The only information about this hypothetical propulsion system is a bunch of conjecture in discussion boards, cheap websites, or Wikis that anyone can screw with. This phenomenon is actually quite common and has been witnessed forming as a result of common civil airlines an military aircraft - even the aging B-52 has been witnessed making this unusual contrail.
 
2007-01-04 01:35:26 PM
This is going to drive the chemtrail conspiracy theorists berserk.
 
2007-01-04 01:55:05 PM
My math may be wrong, but travleing at 3,200 MPH or 4,693 FT/S at 250Hz would mean a detonation every 18.77FT, which would mean at altitude it would be indistinguishable and probobly look like a normal contrail. Unless somehow the aerodynamics of the aircraft combined with the speed created the vortices that then created the donuts.
 
2007-01-04 06:02:28 PM
img232.imageshack.us
 
2007-01-04 07:27:00 PM
These are called 'Donuts on a Rope' and have been the "evidence" of a super-secret, hypersonic, and super-high altitude aircraft being tested (used?) by the Air Force for the last 15 years, at least.

Allegedly.

Aurora.


The link doesn't pop and may contain conspiracy theories that I do not necessarily believe in. I just searched for "Donuts on a Rope" and 'Aurora' and there it was.
 
2007-01-04 07:29:50 PM
These are called 'Donuts on a Rope' and have been the "evidence" of ...


And if I had read the rest of the thread I would see that it has all been laid out already.
 
2007-01-04 08:53:36 PM
Well, if you read his post a bit more closely, you'll see he said something about adjusting the filters to allow it to be indicated. A lot of radar uses range gates and Doppler filtering to remove false returns. If you don't look like a target it's meant to display, you may not show up.

Yeah, I know - I have 2 EE degrees, so range gates and bandpass filters are nothing new to me. I was simplifying that mostly for the great unwashed who don't even know the difference between RADAR and SONAR.
 
2007-01-04 09:42:36 PM
FrancoFile: Yeah, I know - I have 2 EE degrees, so range gates and bandpass filters are nothing new to me. I was simplifying that mostly for the great unwashed who don't even know the difference between RADAR and SONAR.

It baffles me why that is confusing to people but I see it in a lot of movies and novels as well.
 
2007-01-04 10:04:03 PM
erewhon It baffles me why that is confusing to people but I see it in a lot of movies and novels as well.

Probably because they both go "beep". That's about the limit of the intelligence of the average screenwriter...
 
2007-01-06 01:53:30 AM
Gsm136: Because they don't work in water.

hi, have you met my friend humor?
 
Displayed 50 of 50 comments



This thread is archived, and closed to new comments.

Continue Farking
Submit a Link »






Report