Rare Loadouts

[OnlyforDCS]

Thanks for the info and the reply!

 

Sent from my HTC One M8s using Tapatalk

[turkeydriver]

http://www.nasa.gov/centers/dryden/research/Phoenix/phoenixmissile_prt.htm

 

This shows what the retired AIM-54 was proposed to be used for. You can see the F-15 could only carry the weapon where it carried a fuel tank, and barely had enough clearance on the belly. The only modification was the removal of the warhead compartment and replaced with test equipment. Same rocket and flight profile. That's a fast missile, go ahead and try to dodge it. You need to be 13 years old and all hopped up on 10 cans of Mountain Dew to have any hope of a twitch dodge.

[Hummingbird]

F-4 drone in a tight turn hit from long range:

 

Dodging the AIM-54 is going to be real hard.

[GGTharos]

Not much further than 10nm tail-on given that the rocket motor is still burning but regardless.

[Hummingbird]

Not much further than 10nm tail-on given that the rocket motor is still burning but regardless.

 

The engine will definitely burn for longer than 10 nm. Also the drone could've initially been coming in head on seeing that its in a tight turn.

 

IIRC the Phoenix had an engine burn time of 3 min, by which time it should've covered a lot of ground.

Edited February 1, 2016 by Hummingbird

[GGTharos]

The phoenix has an engine burn time of 30 seconds and an acceleration of about 4g (according to the best sources available), much lower than most other missiles. 10nm in tail chase is a well reasoned figure, and quite far too given that other missiles don't make it past 3-4nm with their rocket motor still going.

[Hummingbird]

The phoenix has an engine burn time of 30 seconds and an acceleration of about 4g (according to the best sources available), much lower than most other missiles. 10nm in tail chase is a well reasoned figure, and quite far too given that other missiles don't make it past 3-4nm with their rocket motor still going.

 

Are we talking DCS or real life here? As you probably know the missiles in DCS atm don't achieve anywhere near their real life ranges.

 

AFAIK most radar guided missiles feature a boosting stage and after that a slow burn stage to maintain speed. In other words are you sure the Phoenix doesn't have a 30 sec boost stage and then a 5 times longer slow burn stage? I remember reading something along those lines a long while ago.

 

Otherwise I don't know how the missile was supposed to have a 160+ km intercept range.

Edited February 1, 2016 by Hummingbird

[GGTharos]

We're talking real life. The only piece of (official) paper available shows 27-30 sec burn time at 4000lbf. Nothing's stopping you from having a 142nm intercept range (real world test). The missile will take its time adding 3-3.5 mach numbers above the launch speed, and if you employ properly it'll fly quite far. If your target is coming in at M2 and you launch at M2, you can get an M6.5 average closure. That's close to two minutes flight time, maybe three depending on what happens after the first minute after motor burn-out, in which the Phoenix can maintain an average speed of M4.5 or slightly above.

Edited February 1, 2016 by GGTharos

[Hummingbird]

Hmm...

 

I will gladly admit that I know little when it comes to missiles, but 4000 lbf for 27-30 sec makes good sense for an initial acceleration stage when considering the missile weight (1,000 lbs) and an average max speed of M 4.5 (IIRC the max was M 5.0 at high alt). But after those ~30 sec it should then enter the slow burn state to maintain that speed as best as possible for a while, otherwise how will it reach out to 160+ km? (missile range alone)

 

I say this because Mach 4.5 for 30 sec equals ~45 km (24 nm), but the missile will need time to reach that speed as well, thus a 30 sec burn time won't equal 45 km. Furthermore when the motor shuts off completely speed will start to decrease rapidly due to the rather low sectional density of a missile (esp. when all the propellant fuel is used up).

 

PS: The acceleration of the missile should start out very high and then slow down as speed and therefore drag increases. Thus I don't understand the comment regarding a constant 4 G acceleration?

Edited February 1, 2016 by Hummingbird

[GGTharos]

The max is M5 for a few seconds at high launch mach (specifically mach 2) and high altitude.

 

Those profiles were available for the PMHT until NASA was told to take'em off-line.

 

After 30s the motor's gone. There's no sustainer, and I already did the math for you :)

The missile coasts for about a minute at M4.8 or so under those circumstances; you've already traveled at an average of about 3.7M for 30s accelerating to that speed, so you'll get a flight distance of about 16 + 42 = 58nm before you start dropping below M4.5. That's a minute and a half of flight, during which your target has flown ~25nm, for a total range of ~85nm. If you can keep an average of M4 over the next 30 seconds, you're starting to get up to ~110nm range. In the next 30 seconds you'll close another 20nm, for a total of 130nm. You now have 12nm to cover to reach for the record, and that's going to happen in about a quarter of a minute.

 

No need for magical, non-existing sustainers.

 

Note: Back-of the envelope calculations not guaranteed to be 'on the money', merely 'in the ball-park'.

[Hummingbird]

Just a question: How does the missiles coast at Mach 4.8 for a min without any thrust? By diving? If so that will decrease straight line range due to angle.

 

Also I was refering to the 160+ km (184 km for the C variant apparently) travel range of the missile itself.

 

I guess I'm just having a hard time getting the numbers to match without a graph.

 

 

Btw regarding the different rocket motor stages, that was from a person working with modern missile systems, i.e. it's very real and not something magical. I just assumed that the AIM-54 employed the same technique.

Edited February 1, 2016 by Hummingbird

[GGTharos]

Fair question; I'm not certain, but in the profile I saw it was going through about 100000', and drag up there is going to be quite low. The missile doesn't coast at 4.8 for a minute - that's the average. It goes slightly over M5, then drops to about M4.7-4.5 in about 50sec (time spent over mach 5 is about 8 sec).

 

And I say it's magical and non-existent because there's no sign of it existing. The sparrow has one, the R-27ER has one, but the AIM-54 does not. All of the propellant mass is expended in a steady burn, ie the configuration is all boost (or all sustain if you prefer). There's no indication of a boost-sustain configuration either, and that was quite obvious in the acceleration graph.

 

Under these conditions, the 54 will cover about 100nm by itself within 3 minutes, the target does the other 40nm itself; again this a 50000' to 50000' non-maneuvering, M2 to M2 shot. Drop a mach number and/or altitude and you'll instantly lose 30-50nm of range.

Edited February 1, 2016 by GGTharos

[Hummingbird]

100,000 ft ? Holy cow :shocking:

 

Do you know where I could see the graph?

[GGTharos]

Not any more, used to be on NASA's website but they pulled it down.

[Darkwolf]

Inertia may also help a lot. On top of low drag, that's a quite heavy missile.

[GGTharos]

Turns out it's still out there if you know what to look for, though I believe I saw a more accurate version of this stuff. I might be remembering incorrectly :)

 

 

https: //prod.nais.nasa.gov/eps/eps_data/126521-OTHER-001-001.pdf

[captain_dalan]

That was some good read!

[BlackLion213]

Turns out it's still out there if you know what to look for, though I believe I saw a more accurate version of this stuff. I might be remembering incorrectly :)

 

 

https: //prod.nais.nasa.gov/eps/eps_data/126521-OTHER-001-001.pdf

 

Excellent posts and thank you for the link. I'm learning a ton from you're posting. :)

 

-Nick

[turkeydriver]

F-4 drone in a tight turn hit from long range:

 

Dodging the AIM-54 is going to be real hard.

 

Motor still burning- that's a close range shot-motor only gets you to high altitude and enough to tip over and start the kinetic cruise back down.

[turkeydriver]

The max is M5 for a few seconds at high launch mach (specifically mach 2) and high altitude.

 

Those profiles were available for the PMHT until NASA was told to take'em off-line.

 

After 30s the motor's gone. There's no sustainer, and I already did the math for you :)

The missile coasts for about a minute at M4.8 or so under those circumstances; you've already traveled at an average of about 3.7M for 30s accelerating to that speed, so you'll get a flight distance of about 16 + 42 = 58nm before you start dropping below M4.5. That's a minute and a half of flight, during which your target has flown ~25nm, for a total range of ~85nm. If you can keep an average of M4 over the next 30 seconds, you're starting to get up to ~110nm range. In the next 30 seconds you'll close another 20nm, for a total of 130nm. You now have 12nm to cover to reach for the record, and that's going to happen in about a quarter of a minute.

 

No need for magical, non-existing sustainers.

 

Note: Back-of the envelope calculations not guaranteed to be 'on the money', merely 'in the ball-park'.

 

AFAIK the VMAX for AIM-54 launch was Mach 1.7, unless they only tested to that speed and called it a day....

[GGTharos]

I don't know who this vmax is for, but the f15 launch profiles all show launch at mach 2.

[turkeydriver]

Thanks! I don't have any test data for the F-14B or D but the F-14A in the 1970s was tested to either Mach 1.7 or Mach 1.8 as VMAX for missile launch.

Edited February 3, 2016 by turkeydriver

[Hummingbird]

Motor still burning- that's a close range shot-motor only gets you to high altitude and enough to tip over and start the kinetic cruise back down.

 

I wonder how close though, if its 20 nm then thats a heck of a long way still, esp. in DCS ;)

[GGTharos]

That's not very hard to ball-park ... 4sec/nm in tail-chase. You're looking at about 30/4nm which is 7.5nm max.

[Tirak]

That's not very hard to ball-park ... 4sec/nm in tail-chase. You're looking at about 30/4nm which is 7.5nm max.

 

So this Phoenix is accurately taking out a hard evading target at close range... I think cackling is in order.