Author Topic: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION  (Read 170476 times)

Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #440 on: 09/25/2017 10:59 PM »
Is any information about Cubesats in this flight?

Nope not a thing they are proving as mysterious as the X-37B.

Offline kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #441 on: 09/26/2017 12:38 AM »
That quote tree is based on discussion of radar stealth.

Spray on optical stealth for space is pretty obvious (black paint), so I am pretty sure that isn't what Jim was referring to either.

Last on the list of observation methods would be IR, and control of IR with paint is a consideration in spacecraft thermal design anyway. The RF paint is the obscure one that I wouldn't have guessed existed either if I hadn't heard about it before.

Raised eyebrow... You are going to paint thermal tiles? Also, "black" is not a perfect solution, most blacks will reflect some light. Many C-Type (carbonaceous) asteriods are very "black" and where still found optically. Just because something meets the definition of black does not mean you won't see it if you shine a light on it.

A simpler way to make a satellite "stealthy" to visual observers is some sort of sun screen (umbrella) that shadows the satellite and reflects the incoming solar light away from earth. It has been discussed many times, an actual patent was even filed that is often discussed every time this is brought up. I linked it up thread.

Most obvious explanation is, it is not where we think it is. At this point, everyone is still guessing what orbit it ended up in.
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Offline OneSpeed

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #442 on: 09/26/2017 01:16 AM »
In short, yes you can change plane at any point in a low earth orbit, but changing plane is not the same as changing inclination, unless you do so at the equator.

Wrong

What is meant by a dog leg.  It is during ascent before the vehicle is orbital.   The vehicle flies out at a certain azimuth and then steers to another one which changes the inclination.  The only limitation (other than propellant) is that the vehicle can not go to a lower inclination than the latitude it is at during the maneuver.

Are you sure you are answering my post? I've said nothing about dogleg manoeuvres in this thread.

Also, inclination change does not have to be at the equator.  That is just the most efficient place for the maneuver,.  other locations are not as efficient and are subject to the above limitation.

Yes, that's exactly what I've said a couple of times upthread, I even provided an example.

Online meberbs

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #443 on: 09/26/2017 02:35 AM »
That quote tree is based on discussion of radar stealth.

Spray on optical stealth for space is pretty obvious (black paint), so I am pretty sure that isn't what Jim was referring to either.

Last on the list of observation methods would be IR, and control of IR with paint is a consideration in spacecraft thermal design anyway. The RF paint is the obscure one that I wouldn't have guessed existed either if I hadn't heard about it before.

Raised eyebrow... You are going to paint thermal tiles? Also, "black" is not a perfect solution, most blacks will reflect some light. Many C-Type (carbonaceous) asteriods are very "black" and where still found optically. Just because something meets the definition of black does not mean you won't see it if you shine a light on it.
Was not my original suggestion, I was just countering Jim's claim that there is no such thing as spray on stealth coating. Whether this is a good idea or necessary is a separate issue that I truly don't have an opinion on.

I don't think anyone has ever claimed that any stealth system is perfect, but black is definitely more effective than white for optical stealth in space. That point doesn't change even if there are more effective methods that are just different like what you suggested.

Offline JamesH65

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #444 on: 09/26/2017 09:30 AM »
That quote tree is based on discussion of radar stealth.

Spray on optical stealth for space is pretty obvious (black paint), so I am pretty sure that isn't what Jim was referring to either.

Last on the list of observation methods would be IR, and control of IR with paint is a consideration in spacecraft thermal design anyway. The RF paint is the obscure one that I wouldn't have guessed existed either if I hadn't heard about it before.

Raised eyebrow... You are going to paint thermal tiles? Also, "black" is not a perfect solution, most blacks will reflect some light. Many C-Type (carbonaceous) asteriods are very "black" and where still found optically. Just because something meets the definition of black does not mean you won't see it if you shine a light on it.
Was not my original suggestion, I was just countering Jim's claim that there is no such thing as spray on stealth coating. Whether this is a good idea or necessary is a separate issue that I truly don't have an opinion on.

I don't think anyone has ever claimed that any stealth system is perfect, but black is definitely more effective than white for optical stealth in space. That point doesn't change even if there are more effective methods that are just different like what you suggested.

Clearly there is such a thing as spray on stealth paint.

And for optical stealth, just use vantablack. That stuff doesn't reflect anything. Well, 99.96% absorbency. So 0.04% reflection. Also works as thermal camouflage.

Offline Mike_1179

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #445 on: 09/26/2017 01:05 PM »
Stealth is about much more than “hard to see it”

A stealth aircraft needs to communicate, and waveguide antennas are big, flat, metal plates. You put one of those on the outside of your vehicle and it will light up great on radar. Stick it underneath all of your fancy radar-absorbing structure and communication signals can’t get to it. A frequency-selective surface which allows communication transmission with limited loss but absorbs (not reflects) other frequencies is not spray-on.

There’s more to stealth than smooth edges, black paint and microwave-attenuating coverings.

Offline SmallKing

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #446 on: 09/26/2017 01:10 PM »
Ted said the current 37B orbit is about 7 deg from the expected RAAN. So, how much energy the Falcon 9 wasted to reach this orbit?
http://satobs.org/seesat/Sep-2017/0118.html
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Offline kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #447 on: 09/26/2017 01:57 PM »
Ted said the current 37B orbit is about 7 deg from the expected RAAN. So, how much energy the Falcon 9 wasted to reach this orbit?
http://satobs.org/seesat/Sep-2017/0118.html
The consensus in following SeeSat posts seems to be they recovered TecSar and it is not OTV-5.
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Offline Jim

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #448 on: 09/26/2017 03:56 PM »

Clearly there is such a thing as spray on stealth paint.

And for optical stealth, just use vantablack. That stuff doesn't reflect anything. Well, 99.96% absorbency. So 0.04% reflection. Also works as thermal camouflage.

Not spray on

Offline Skyrocket

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #449 on: 09/26/2017 05:20 PM »

Clearly there is such a thing as spray on stealth paint.

And for optical stealth, just use vantablack. That stuff doesn't reflect anything. Well, 99.96% absorbency. So 0.04% reflection. Also works as thermal camouflage.

Not spray on


And it would give the satellite a huge IR footprint.

Offline kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #450 on: 09/26/2017 06:22 PM »
I will also remind you of history of the X-15 and it's 'pink' spray on ablative thermal insulation. It was an attempt at send the X-15 higher and faster. It was also a total flop, when burning off it charred,  leading to excessive  local heating, increased drag, and covered the windows with soot.

Any "stealth" coating applied (be it by hand or sprayed on) to OTV-5 will have similar negative impacts as it burns off. The soot will create localized hot spots, it will char leading to increased drag, if it doesn't burn off evenly it could lead to asymmetrical drag at hypersonic speeds (with loss of control), and then cover with soot sensors needed for a safe landing.

That is why many here (like Jim) think the whole idea of applying a stealth coating/paint/tar/spit balls to the vehicle is bonkers.

Don't forget, Stealth does not work very we at long wavelengths (low frequency). When the vehicle is much shorter than the 1/4 wave, it will act like a short dipole (re radiate the energy). Over the horizon early warning radars operate at these longer wavelengths. That is also why everyone is saying stealth will not buy you much.
« Last Edit: 09/26/2017 06:23 PM by kevin-rf »
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Offline Ben the Space Brit

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #451 on: 09/27/2017 10:03 AM »
IIRC, thermal resistance has always been a huge issue for most low-observability materials.

Are there any practical active systems that could be used?
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Offline garcianc

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #452 on: 09/27/2017 12:54 PM »
Please forgive me if this is an ignorant question but, hearing all this speculation about stealth techniques got this old military man thinking. Doesn't this vehicle have solar panels? It would seem to me that making those stealth would be tough.

For whatever is worth, from my experience as a submariner, the best stealth method is the most basic: hide.

Online jpo234

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #453 on: 09/27/2017 01:06 PM »
Please forgive me if this is an ignorant question but, hearing all this speculation about stealth techniques got this old military man thinking. Doesn't this vehicle have solar panels? It would seem to me that making those stealth would be tough.

For whatever is worth, from my experience as a submariner, the best stealth method is the most basic: hide.

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Offline kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #454 on: 09/27/2017 01:07 PM »
Please forgive me if this is an ignorant question but, hearing all this speculation about stealth techniques got this old military man thinking. Doesn't this vehicle have solar panels? It would seem to me that making those stealth would be tough.

For whatever is worth, from my experience as a submariner, the best stealth method is the most basic: hide.

Simple answer on the solar panels, is they are always pointed at the sun, so you only see the back side in shadow. You can make them so no light goes through the structure.  The long answer to that is as you head towards sunset in orbit, the angle of reflection off of them will at some point intersect with the ground (which is in shadow) so you will get a flare. Now deliberately controlling the flare angle by tilting the panels up a little as you head towards the terminator would prevent that at the cost of some power generation.   

I agree, up to this point OTV-5 is using the best method possible. Hiding!

That said this OTV-5 mania has me checking every bright satellite. Then I checked Heavens-Above and it is ISS or some spent stage ;-) FWIW: ISS should have a very bright east coast pass tonight, it will have an elevation of about 87 degrees over boston at around 7:45ish.
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Online Zed_Noir

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #455 on: 09/28/2017 06:24 AM »
My speculation is that the X-37B could have a deployable non-symmetrical EM shade on a boom on the opposite side of the solar array. That also reduces the visual footprint of the vehicle.

Offline zubenelgenubi

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #456 on: 10/08/2017 07:35 PM »
Seesat-l news, a few days old:

Russell Eberst reports single sighting of an unknown bright satellite on the morning of October 3 (magnitude +2.7 if I understand his table correctly), possibly OTV-5: http://www.satobs.org/seesat/Oct-2017/0007.html

Ted Molczan then generated search elements for an assumed, quasi-55 deg. inclined orbit here: http://www.satobs.org/seesat/Oct-2017/0009.html

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Quote
It is recommend to use wide field optics, or on favourable passes, the unaided eye. Avoid observing close to the predicted intersection with Earth's shadow.

(My note: This is definitely differing from assumptions of a 43 deg. inclined orbit elsewhere, such as www.heavens-above.com .)

No further observations mentioned on Seesat-l between October 3 and today, October 8.
« Last Edit: 10/08/2017 07:39 PM by zubenelgenubi »
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Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #457 on: 10/16/2017 06:44 AM »
Have a look at the picture in reply #637 page 43 kindly posted on the Secret Projects Forum in this thread, notice the X-37B model in the background. Me thinks perhaps that model should have been taken down before people started shooting off photos of official visits to Global Strike Command.

https://www.secretprojects.co.uk/forum/index.php/topic,5232.0.html
« Last Edit: 10/16/2017 06:51 AM by Star One »

Offline kevin-rf

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #458 on: 10/16/2017 10:36 AM »
Do you need to be logged in or something? Reply 637 in that thread no longer has the picture. At least on a mobile device.
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Offline Star One

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Re: SpaceX Falcon 9 : X-37B OTV-5 : September 2017 : DISCUSSION
« Reply #459 on: 10/16/2017 12:14 PM »
Do you need to be logged in or something? Reply 637 in that thread no longer has the picture. At least on a mobile device.

Yes sorry. Because I am always logged in I forgot.

Apparently another poster said the same model featured in a 60 minutes documentary two years back so it obviously isn’t as intriguing as thought.


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