F-35 Ready For Missile Defense By 2025: MDA Chief

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marauder2048

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Unread post07 Aug 2020, 21:57

steve2267 wrote:
mixelflick wrote:I can't tell from all the flip flopping if the F-35 is still being investigated for missile defense, but I think it needs to be. No other sensor platform is so robust, at least insofar as also being so highly mobile.

If it works, it will be a boon to both homeland defense and any theater of operation it flies in. From N. Korea to North Dakota to the SCS, it sounds like precisely what we need. The biggest issues seem to be extending range/loiter capability (while preserving stealth) and getting a dedicated missile on it, to further shorten reaction time needed to shoot down an IRBM, ICBM etc..


Are you saying the F-35 would be a boon to missile defense flying out of North Dakota? Prey tell, how?


F-35s with air launched, terminal interceptors.

The things you want for boost phase translate pretty well into terminal phase interceptors.
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blindpilot

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Unread post08 Aug 2020, 02:00

marauder2048 wrote:....

The things you want for boost phase translate pretty well into terminal phase interceptors.


...???? Hmmm. ... No ... < Mach 1 boost phase launch is not equal to Mach 13-20 terminal velocities...

MHO
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steve2267

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Unread post08 Aug 2020, 05:23

blindpilot wrote:
marauder2048 wrote:....

The things you want for boost phase translate pretty well into terminal phase interceptors.


...???? Hmmm. ... No ... < Mach 1 boost phase launch is not equal to Mach 13-20 terminal velocities...



Phrased slightly differently... terminal phase interceptors of ICBM's need something like a minimum velocity of 8 Mach, if not 10-15 Mach. There's a reason GBI really moves out quick. An F-35 out of Grand Forks is going to have to heave a missile capable of accelerating to very high Mach numbers, and that missile ain't gonna be small. The ASAT system tested by the US in the '80s was NOT small, and an F-15 could only haul one aloft, if memory serves. If that thing could intercept a satellite, it might have a shot at an ICBM re-entry vehicle. But the F-35 sensor suite isn't going to help you intercept an ICBM from Grand Forks. If it is even feasible... I will allow that might be the perfect mission for an F-15EX. <gag>
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marauder2048

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Unread post08 Aug 2020, 20:40

blindpilot wrote:
marauder2048 wrote:....

The things you want for boost phase translate pretty well into terminal phase interceptors.


...???? Hmmm. ... No ... < Mach 1 boost phase launch is not equal to Mach 13-20 terminal velocities...

MHO
BP


Please familiarize yourself with boost phase interceptor design; the need to catch a boosting missile (since you won't have
perfect warning, only know the general location, may have late detection depending on the cloud layer),
from some degree of standoff drives *very* high Vbo -> 3 - 6 km/s.

For reference, even the AMRAAM form-factor NCADE was supposed to be around 2 km/sec.

Re-entry Vehicles aren't moving that fast terminally and would be within the enveloped of 3 - 6 km/sec interceptor.
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Unread post08 Aug 2020, 20:58

steve2267 wrote:

Phrased slightly differently... terminal phase interceptors of ICBM's need something like a minimum velocity of 8 Mach, if not 10-15 Mach. There's a reason GBI really moves out quick.


It's neither a boost nor a terminal phase interceptor. It gets to its Vbo rather leisurely (something like > 200 sec burn time).

steve2267 wrote: An F-35 out of Grand Forks is going to have to heave a missile capable of accelerating to very high Mach numbers, and that missile ain't gonna be small.


Around 2000 lbs, capable of fitting in the F-35 bays.
Should be in the 4.5 km/sec range. It's been looked at many times.

steve2267 wrote:The ASAT system tested by the US in the '80s was NOT small, and an F-15 could only haul one aloft, if memory serves.


This is endo terminal defense right? That drives a very different design.

steve2267 wrote:But the F-35 sensor suite isn't going to help you intercept an ICBM from Grand Forks.


This is terminal defense where the the F-35's sensor suite permits it to engage with minimal cueing.
And it's not dependent on whether someone remembered to reserve the IRST that day.
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element1loop

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Unread post09 Aug 2020, 05:21

marauder2048 wrote:Around 2000 lbs, capable of fitting in the F-35 bays. Should be in the 4.5 km/sec range. It's been looked at many times.


A possible problem with this is the interceptor's max speed is highly dependent on the launch aircraft's Mach-vector, and altitude. What you say may work OK for a regular RV, with track data supplied mid-course for an expected aim point (which alone is incredibly useful), but an agile fast RV presents some issues with getting the F-35 properly oriented and accelerated, some of the time. It could do a HOBS shot, or high AOA launch, but that's a heavy weapon, and inertial means that would be far from an optimum achievable launch state, with a non-linear affect to range and top speed.

Plus the F-35 must be as high altitude and moving as fast as possible at launch, yet not burn its fuel down too fast, to consistently get a high Mach speed from the interceptor. It's probably doable but getting the speed and range against a low-drag agile RV will be tricky (+1G acceleration), as the engagement would still occur well above 50,000 ft, where the RV is still in very thin air and moving extremely fast.

i.e. The RV won't slow that much until it drops well below 50,000 ft, which means an interceptor rising to meet it will be dealing with a very fast and increasingly agile RV as it descends. If an interceptor launch were lower and slower, say at 35,000 ft and Mach 1.1 the interceptor's top speed will be about Mach 1.5 slower, and its range a lot shorter (so needs to be launched from closer to the RV's actual target).

A launch platform that easily sustains stable super-cruise and rapid acceleration, plus vertical performance from 55,000 ft to 65,000 ft, would be better. A high-performance high-altitude long-loiter agile flying-wing drone, with F-35-like systems, for instance.

Hope the IFF works well.
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Unread post09 Aug 2020, 21:34

element1loop wrote:
marauder2048 wrote:Around 2000 lbs, capable of fitting in the F-35 bays. Should be in the 4.5 km/sec range. It's been looked at many times.


A possible problem with this is the interceptor's max speed is highly dependent on the launch aircraft's Mach-vector, and altitude. What you say may work OK for a regular RV, with track data supplied mid-course for an expected aim point (which alone is incredibly useful), but an agile fast RV presents some issues with getting the F-35 properly oriented and accelerated, some of the time. It could do a HOBS shot, or high AOA launch, but that's a heavy weapon, and inertial means that would be far from an optimum achievable launch state, with a non-linear affect to range and top speed.


What is an "agile" RV? A MaRV? MaRVs are larger and heavier than typical RVs so a many interceptor:1 RV
engagement is fine; the accompanying decoys burn up before most non-exotic MaRVs can maneuver much.

element1loop wrote:Plus the F-35 must be as high altitude and moving as fast as possible at launch, yet not burn its fuel down too fast, to consistently get a high Mach speed from the interceptor. It's probably doable but getting the speed and range against a low-drag agile RV will be tricky (+1G acceleration), as the engagement would still occur well above 50,000 ft, where the RV is still in very thin air and moving extremely fast.


Most of the interceptor designs were motivated by X-47B or UCAV considerations where they are subsonic
but slightly higher in endurance altitude. This is offset by the ability fo the F-35 to accelerate and climb.

"in very thin air" hence DACS or some other form of non-aerodynamic control common
to just about every interceptor that operates in this envelope.

element1loop wrote:i.e. The RV won't slow that much until it drops well below 50,000 ft,


Completely untrue if you look at any modern RV velocity @ altitude profile.

element1loop wrote:which means an interceptor rising to meet it will be dealing with a very fast and increasingly agile RV as it descends. If an interceptor launch were lower and slower, say at 35,000 ft and Mach 1.1 the interceptor's top speed will be about Mach 1.5 slower, and its range a lot shorter (so needs to be launched from closer to the RV's actual target).


Unless we are talking about MaRVs the notion of agility is irrelevant. The typical notion of MaRVs is
that they are a sink for a large number of interceptors. 2000 lbs interceptors would have plenty of
agility so even a 2:1 engagement leaves the defender in the same position since even the simplest
course correcting MaRV tends to displace some number of RVs either by weight or volume.

course-correcting-mk4-rv.png


element1loop wrote:A launch platform that easily sustains stable super-cruise and rapid acceleration, plus vertical performance from 55,000 ft to 65,000 ft, would be better. A high-performance high-altitude long-loiter agile flying-wing drone, with F-35-like systems, for instance.
Hope the IFF works well.


Naturally, it would be great if we had a super-cruising + rapidly accelerating platform
that had great vertical performance in the 50 kft - 65 kft. And whose bays could accommodate
the outsized interceptor volumes and weights required for the mission.

And that could be deployed in quantity. I wouldn't hold your breath.

A high-performance high-altitude long-loiter agile flying-wing drone,


Which are practically mutually exclusive requirements.
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steve2267

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Unread post09 Aug 2020, 22:11

marauder2048 wrote:
Completely untrue if you look at any modern RV velocity @ altitude profile.



I would welcome any links to any such publicly available (e.g. opensource) data / figures / charts / graphs / papers etc.
Take an F-16, stir in A-7, dollop of F-117, gob of F-22, dash of F/A-18, sprinkle with AV-8B, stir well + bake. Whaddya get? F-35.
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Unread post09 Aug 2020, 23:58

steve2267 wrote:
marauder2048 wrote:
Completely untrue if you look at any modern RV velocity @ altitude profile.



I would welcome any links to any such publicly available (e.g. opensource) data / figures / charts / graphs / papers etc.


The Adams paper (pg. 10 figure 4a) has a high-Beta, 1000, RV compared to a MaRV.

Figure 16 from Postol is a lower Beta RV but the velocity/altitude profiles are still useful
Fig16.jpg


https://www.aps.org/units/fps/newsletters/201804/north-korea.cfm
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Unread post10 Aug 2020, 06:28

marauder2048 wrote:The Adams paper (pg. 10 figure 4a) has a high-Beta, 1000, RV compared to a MaRV.

Figure 16 from Postol is a lower Beta RV but the velocity/altitude profiles are still useful
Fig16.jpg




marauder2048 wrote:
element1loop wrote:i.e. The RV won't slow that much until it drops well below 50,000 ft,


Completely untrue if you look at any modern RV velocity @ altitude profile.


What you've just posted confirms what I said, most of the slowing occurs below 50,000 feet, i.e. below 14 to 15 km altitude.
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Unread post10 Aug 2020, 06:39

marauder2048 wrote:
A high-performance high-altitude long-loiter agile flying-wing drone,


Which are practically mutually exclusive requirements.


Disagree.

That, plus sufficient control surface and thrust overhead from an efficient 3-path engine and 2D vectored nozzle would certainly suffice. Funding it is the issue, but such an aircraft would also make an ideal medium-range bomber escort (if not a striker in its own right), and serve many, many other useful air dominance functions. Not a niche one-trick pony.
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Unread post10 Aug 2020, 16:11

element1loop wrote:
What you've just posted confirms what I said, most of the slowing occurs below 50,000 feet, i.e. below 14 to 15 km altitude.


Or more specifically it's still doing Mach 17 at 85,000 feet, and Mach 8 in the dense 35,000 feet air. The posted deceleration curve is far more challenging (varying aero forces) than the predictable boost phase (fixed thrust) curves.

The boost phase and terminal phase are simply different problems apart from basic physics. Mid phase, lowest speed, most predictable trajectory, etc. remains the easier answer. But the three Boost, Mid, Terminal are not common enough to "carry over" much of the engineering.

I'll bow out of the conversation since although years old, I'm not sure what I got working at NORAD is now unclassified, and converting metrics to Mach/feet hurts my old brain.

MHO,
BP
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Unread post10 Aug 2020, 21:28

element1loop wrote:
marauder2048 wrote:The Adams paper (pg. 10 figure 4a) has a high-Beta, 1000, RV compared to a MaRV.

Figure 16 from Postol is a lower Beta RV but the velocity/altitude profiles are still useful
Fig16.jpg




marauder2048 wrote:
element1loop wrote:i.e. The RV won't slow that much until it drops well below 50,000 ft,


Completely untrue if you look at any modern RV velocity @ altitude profile.


What you've just posted confirms what I said, most of the slowing occurs below 50,000 feet, i.e. below 14 to 15 km altitude.


By 50,000 ft, the RV has lost nearly 50% of its velocity.
Between 50 kft - 75,000 kft the RV is between 3 km/s - 5 km/s.
That's exactly the engagement envelope for an interceptor in the 3 - 5 km/sec range.

Zachran was suggesting in a recent paper (the follow-on to https://www.hsdl.org/?view&did=687583)
that interceptors in the 6 km/s would be feasible with the recent advances in very light KVs.
Last edited by marauder2048 on 10 Aug 2020, 21:52, edited 2 times in total.
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Unread post10 Aug 2020, 21:31

blindpilot wrote:The boost phase and terminal phase are simply different problems apart from basic physics. Mid phase, lowest speed, most predictable trajectory, etc. remains the easier answer. But the three Boost, Mid, Terminal are not common enough to "carry over" much of the engineering.



Boost and Terminal phases require very fast, very agile interceptors. The US collects vast amounts of data on
foreign RVs such that their deceleration profiles are pretty well known. Similar to boost profiles.
It's much easier to vary a boost profile or boost trajectory (including booster separation times)
though which makes boost guidance laws tricky.

The guidance laws for terminal interception have a similar problem in looking at a constantly accelerating
(with a negative sign) RV. But high-aspect angle shots (i.e. head on) minimize the apparent acceleration.

blindpilot wrote:I''ll bow out of the conversation since although years old, I'm not sure what I got working at NORAD is now unclassified, and converting metrics to Mach/feet hurts my old brain.


Thanks for adding substantially less to the conversation than what Corbett and Zachran did in like a page.
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Unread post10 Aug 2020, 22:18

element1loop wrote:
marauder2048 wrote:
A high-performance high-altitude long-loiter agile flying-wing drone,


Which are practically mutually exclusive requirements.


Disagree.

That, plus sufficient control surface and thrust overhead from an efficient 3-path engine and 2D vectored nozzle would certainly suffice. Funding it is the issue, but such an aircraft would also make an ideal medium-range bomber escort (if not a striker in its own right), and serve many, many other useful air dominance functions. Not a niche one-trick pony.


This is in essence the holy grail of aerospace design: fighter-like high performance + high altitude + long loiter.

You would have to employ some form of boundary layer control to get laminar flow, for loiter, over
wings designed for high performance. There is an argument for using the third stream to do this.

But the amount of pitching moment a 2D TVC can contribute a high loiter altitudes is going to be
small just by virtue of the drop-off in engine thrust @ altitude.

So you'll need a lot of control surface weight, area to do the rest.
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