Operational Performance Comparison: Viper, Beagle and Stubby

eloise · by **eloise** » 19 May 2019, 17:30

sprstdlyscotts wrote: Go back a few pages and you will see my analysis on using the C-5 motor and how big of a difference loft makes. The C-7 is supposed to have "significant" range increase from the C-5 and the D has a 50% range improvement over.

C-6 and C-7 use same motor from C-5 and i don't think they mentioned range improvement

wrightwing · by **wrightwing** » 19 May 2019, 17:51

eloise wrote:
sprstdlyscotts wrote: Go back a few pages and you will see my analysis on using the C-5 motor and how big of a difference loft makes. The C-7 is supposed to have "significant" range increase from the C-5 and the D has a 50% range improvement over.

C-6 and C-7 use same motor from C-5 and i don't think they mentioned range improvement
2F007828-9162-4F8E-A64E-497B3F31ABCF.jpeg

The C7 has a significant range improvement over the C5, due to improved flight profiles/navigation. The D improves on that further still.

spazsinbad · by **spazsinbad** » 19 May 2019, 17:55

Please - is there any chance that the above graphic can be uploaded to this forum rather than viewed from PhotoBuckit?

sprstdlyscottsmn · by **sprstdlyscottsmn** » 19 May 2019, 18:56

basher54321 wrote:
sprstdlyscottsmn wrote:What is FMCW?

Frequency Modulated CW ?

How does it work? Does the illumination radar change frequency based on range so that the receiver in the missile knows the range?

basher54321 · by **basher54321** » 19 May 2019, 19:15

http://www.radartutorial.eu/02.basics/F ... ar.en.html

swiss · by **swiss** » 19 May 2019, 20:07

wrightwing wrote:
eloise wrote:
sprstdlyscotts wrote: Go back a few pages and you will see my analysis on using the C-5 motor and how big of a difference loft makes. The C-7 is supposed to have "significant" range increase from the C-5 and the D has a 50% range improvement over.

C-6 and C-7 use same motor from C-5 and i don't think they mentioned range improvement
2F007828-9162-4F8E-A64E-497B3F31ABCF.jpeg

The C7 has a significant range improvement over the C5, due to improved flight profiles/navigation. The D improves on that further still.

Interesting. So the AIM-120 had only one Rocket size upgrade (C-5). And all the other range improvements where done thanks to flight profiles/navigation upgrades?

sprstdlyscottsmn wrote: Pk is never above 78% as I assume that to be the overall missile Pk for the AMRAAM.

This is also in line with the testimony of an EF pilot. He said the error rate of a modern missiles is always at least 20%.

Your calculations also show very impressively, how dangerous the combination Meteor/AESA radar is, from a long distance against a non stealthy target.

SpudmanWP · by **SpudmanWP** » 19 May 2019, 21:35

spazsinbad wrote:Please - is there any chance that the above graphic can be uploaded to this forum rather than viewed from PhotoBuckit?

Yeah, I moved to imgur a few years back.

spazsinbad · by **spazsinbad** » 20 May 2019, 01:48

Thanks 'SWP'. :applause:

garrya · by **garrya** » 20 May 2019, 02:51

While looking for information about R-40 guidance, I coincidently ran into this:

https://books.google.com.vn/books?id=rg ... &q&f=false

If R-40 with its big fin can't sustain controlled flight above 27 km, then it is quite unlikely AIM-120 can be loft above this altitude, IMHO, it won't be able to pitch down or change direction once loft to this altitude

sprstdlyscottsmn · by **sprstdlyscottsmn** » 20 May 2019, 04:35

My model takes air density into account. The high altitude shots with the AIM-120 involve it using gravity to get down on the target and sustained surface deflection at Mach five when needed.

garrya · by **garrya** » 20 May 2019, 05:39

sprstdlyscottsmn wrote:My model takes air density into account. The high altitude shots with the AIM-120 involve it using gravity to get down on the target and sustained surface deflection at Mach five when needed.

But if R-40 with bigger wing and faster speed can't be controlled, isn't it much more difficult with AIM-120?
in your model what is the turn rate of AIM-120 at an altitude of 21 nm?

hornetfinn · by **hornetfinn** » 20 May 2019, 06:19

That Phoenix missile Hypersonic Testbed pdf states that the Phoenix missile is can go up to 150 kft until there is not enough controllability. So it seems very likely that AIM-54 missile has superior high altitude performance to R-40 missile even though the latter has larger fins. It's just not the size of the fins and wings that matters. It also depends on how powerful the control systems are and more modern control systems are far more powerful than those designed 60 years ago. Modern missiles have far superior maneuverability compared to older missiles. They can now make 40-50 G turns when 1960s missiles could do less than half of that despite having much larger control surfaces.

garrya · by **garrya** » 20 May 2019, 07:25

hornetfinn wrote:That Phoenix missile Hypersonic Testbed pdf states that the Phoenix missile is can go up to 150 kft until there is not enough controllability. So it seems very likely that AIM-54 missile has superior high altitude performance to R-40 missile even though the latter has larger fins

IMHO, the rectangle control surface of AIM-54 is bigger than the triangle control surface of R-40, furthermore, it put farther aft so the pivot is greater.
Besides, the Phoenix in the hypersonic test has lighter weight than normal Phoenix

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hornetfinn wrote: It's just not the size of the fins and wings that matters. It also depends on how powerful the control systems are and more modern control systems are far more powerful than those designed 60 years ago.

IMHO, the strength of the actuator is not the issue because at high altitude, where the air is thin, it is easier to turn the fin.

garrya · by **garrya** » 20 May 2019, 15:01

sprstdlyscottsmn wrote:Okay, so sometimes the discussions here make me look into things, which causes me to re evaluate things. In this case, I looked into the case of the Meteor shooting at the Foxhound. When I did the 50,000ft shot I realized even the 4 degree loft lent it to 100,000ft+ I did not like that. So, I made a simple (and hopefully robust) "max alt limit" for the Meteor. Now it can only loft to 85,000ft, an altitude at which the minimum throttle setting results in acceleration to Mach 4.5. "Well, that sure made it hit the MiG-31 harder. Gee, I wonder how far out I can take this shot". Sitting at 280nm launch range and hitting the target at 4.5M with 72%Pk (max for the Meteor, having two motor functions impacted reliability to me).

@Spurt, would you mind posting the chart for this part
72%PK from 280 nm is just too good to miss

sprstdlyscottsmn · by **sprstdlyscottsmn** » 20 May 2019, 15:25

garrya wrote: in your model what is the turn rate of AIM-120 at an altitude of 21 nm?

Dismal. 1.9G, less than 1 degree per second. The point is that for that shot in particular there is no need to turn. Here is the actual G force commanded for the flight of that shot.

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Remember the MiG won't know anything is happening until the seeker goes active. By that time the air is thick enough to pull 10G to the MiGs 5 at best. At the point of impact just over 15G is available to the missile. All that in 7 seconds. I bet it takes more than three seconds from time RWR goes off to even roll the plane over to start turning. Nothing is happening quickly at that speed and altitude.

garrya wrote: @Spurt, would you mind posting the chart for this part
72%PK from 280 nm is just too good to miss

Here is the Alt, Speed, and G profile for that shot.

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