R-27ER Experiment & Findings

[Dudikoff]

You would have to judge for yourself' date=' there is info out there on both missiles, the general figure given for the AIM-7M is about 50km being its max range, some sources are slightly higher, some are slightly lower, there is also info out there about the R-27R and ER, with figures for the R of about 70-80km, and the ER of about 120-130km.[/quote']

 

Well, the Germans said here it's max 30 km for the R-27R at high altitude and expect around 50 km for the ER. Those numbers you mention are max aerodynamic range or something silly like that and are not representing range against a target at the same altitude. For example, even the Su-27SK manual states head-on ranges as 2 - 42 km for the R and 2 - 65 km for the ER depending on the conditions such as height and speed of the aircraft and its target; the higher values are obviously for when the target is at a lower height than the launching aircraft (up/down to 10 and 12 km height difference for the R and ER respectfully).

 

http://www.fabulousfulcrums.de/index_e.html

Edited March 2, 2017 by Dudikoff

[Capn kamikaze]

Yes, they are, and that is what we're talking about, you can define max kinematic range quite well, but max effective range is more down to a judgement.... and the max range of the AIM-7M is about 50km, and its effective range if you use real world engagements as a measure is at most 30km, eg in GW1, and most launches that resulted in kills in that war were at about the 20km mark.

[Sweep]

You would have to judge for yourself, there is info out there on both missiles, the general figure given for the AIM-7M is about 50km being its max range, some sources are slightly higher, some are slightly lower, there is also info out there about the R-27R and ER, with figures for the R of about 70-80km, and the ER of about 120-130km.

 

So take that for what you will, but remember the R-27 is a larger missile, with a bigger motor, but not much heavier, so it's highly likely it will have longer burn time and thrust so a longer range is pretty much assured.

 

Yes, the R-27 is bigger and heavier...Remember what the first one means when you're doing Mach 3.5+. :D

 

Also, R-27 and AIM-7 have a 60 second max controlled flight time, IIRC.

[Dudikoff]

and the max range of the AIM-7M is about 50km' date=' and its effective range if you use real world engagements as a measure is at most 30km, eg in GW1, and most launches that resulted in kills in that war were at about the 20km mark.[/quote']

 

Is the data on GW1 engagements available in detail in some report on a case by case basis? Because, the range would vary greatly with altitude and if it's a front or rear hemisphere shot. IIRC, lots of kills later on were made against Iraqi planes running off to Iran, so I'd expect those were rear hemisphere shots.

[Capn kamikaze]

Get a copy of "Gulf Air War debrief", there are accounts of quite a few of the engagements in there, and plenty of other topics like the airstrikes, and naval aviation, the later engagements tended to be against strike aircraft like Su-22's etc, some were no doubt rear hemisphere shots.

 

Also don't forget that if we're going to compare the R-27 to the AIM-7 then you have to consider that the AIM-7's airframe was established in the late 1950's, and that set the physical size of the later versions, the R-27 was designed about 20-30 years later, so fitting a bigger more powerful motor was an option, were as with the AIM-7F/M/P it was constrained by what had already been established decades before.

Edited March 2, 2017 by Cap'n kamikaze

[DarkFire]

Get a copy of "Gulf Air War debrief"' date=' there are accounts of quite a few of the engagements in there, and plenty of other topics like the airstrikes, and naval aviation, the later engagements tended to be against strike aircraft like Su-22's etc, some were no doubt rear hemisphere shots.[/quote']

 

I'd definitely recommend that to anyone with an interest in 'modern' military aviation. It's a very interesting read. I'd count it as one of the very few reliable sources for information on the real-world performance of the sort of SARH missiles we have in DCS at the moment. With reservations, of course, but in the absence of any published test data...

[lunaticfringe]

...so fitting a bigger more powerful motor was an option' date=' were as with the AIM-7F/M/P it was constrained by what had already been established decades before.[/quote']

 

The AIM-7, in its various forms, received three engines- with the last (the Mk 58/Mk 65, depending on manufacturer) taking it out to an effective range just short of 40 miles. The size of what's inside, and the power it carries chemically, matters just as much as the outside.

[Capn kamikaze]

The AIM-7, in its various forms, received three engines- with the last (the Mk 58/Mk 65, depending on manufacturer) taking it out to an effective range just short of 40 miles. The size of what's inside, and the power it carries chemically, matters just as much as the outside.

 

That's all that could really do, change the chemical composition and design of the motor, without a major airframe redesign, and doing that would cause problems, if you made it bigger overall, or did what the Russians did with the R-27 and simply make the back end bigger to make the ER, then any airplane that carried the AIM-7 semi-recessed would either need to be modified or simply not be able to carry the new shape.

[*Rage*]

I graduated in summer and I'm quite wrapped up at work. I'm not at home for the most part and my flight gear is there and I'm having a really tough time getting through this winter. Honestly I've been surfing on the border of being sick since the end of november, sometimes under the wave.

 

Anyway, I want to apologize to both you and Frostie for being completely unreasonable. I tried my best not to offend or attack either of you but I know in the end I kind of just made an ass out of myself. I still believe what my experience tells me, but should've taken a different approach to the discussion.

 

When I do get back to flying I'm gonna start testing loads of stuff though, I have soooo many ideas. :)

 

No worries man. This discussion always gets heated because we're so passionate about it:thumbup: Good luck with work and hope to see you back online soon. Collectively the 104th and 51st have had some epic flights over the years. Hopefully it continues.

[Drona]

What started as an R-27ER thread has now evolved into a discussion about the AIM-7M!!! :doh:

 

Anyways, I really wish ED does something about the general SARH situation and especially the R-27ER, R-27R, and AIM-7M. Also, the ARH missiles should perform a lot better than they currently do. It's been almost 5 years since the release of the AFM A2A missiles and nothing much has really changed since that time and might I say its been a frustrating 5 years experience to the extent that its much more enjoyable to fly the ground pounders than A2A.

 

I just feel this integration or merge is taking way too long, which incidently has also taken around 5 years and still ongoing. The answer I'm most likely to get is there is an engineer working on the missiles and they are two different teams [insert additional lame excuse here]. All I'm saying its about time something's done about this instead of us customers continually complaining and arguing about missiles.

[holimoli]

I just feel this integration or merge is taking way too long, which incidently has also taken around 5 years and still ongoing. The answer I'm most likely to get is there is an engineer working on the missiles and they are two different teams [insert additional lame excuse here]. All I'm saying its about time something's done about this instead of us customers continually complaining and arguing about missiles.

 

FM is beta! Everything is beta.

[Capn kamikaze]

What started as an R-27ER thread has now evolved into a discussion about the AIM-7M!!! :doh:

 

Well yeah, because the R-27ER does not exist in a vacume.

[Capn kamikaze]

I just feel this integration or merge is taking way too long, which incidently has also taken around 5 years and still ongoing.

 

The reason for that is fairly obvious, it is more profitable for ED to focus on aircraft and map modules than actually fixing the fundamentals....

 

Someone had to say it, so it may as well be me.

[lunaticfringe]

That's all that could really do' date=' change the chemical composition and design of the motor, without a major airframe redesign...[/quote']

 

Considering the AIM-120D more than doubles the range of the AIM-7F/M in the same carriage area, currently with ten inches of internal depth unused, you'd be amazed at what an missile can do without a major airframe redesign with the right available technology.

[Capn kamikaze]

Considering the AIM-120D more than doubles the range of the AIM-7F/M in the same carriage area, currently with ten inches of internal depth unused, you'd be amazed at what an missile can do without a major airframe redesign with the right available technology.

 

And a major part of the reason the AIM-120 in general can fly further is because of the much smaller control surfaces, which obviously means much less drag than the AIM-7.

[lunaticfringe]

Just half an hour ago your argument was that Raytheon was constrained on range by nature of the available profile and engine size, and now you're mentioning clipped fins.

 

Interesting.

[Capn kamikaze]

I'm mentioning it as part of the reason why the AIM-120 has a range advantage over the AIM-7 while both missiles have very similar dimensions.

 

Its not "interesting" as you would like to characterize it.

 

There was never any version of the AIM-7 that had control surfaces as small as even the AIM-120A or B, if there was that would have helped, but..... there wasn't.

 

The R-27 has a lot more control surface area than both the AIM-120 and AIM-7, but it has a lot bigger motor.....

 

Come on, it's not that hard to follow....

 

I find it "interesting" that you would like to try to pretend I am contradicting myself, I note how you conveniently didn't mention I was comparing the AIM-7 to the AIM-120, and the major physical difference between them being the drag inducing parts, while their volume is fairly similar, it's almost as if you're picking and choosing which bits of what I have said you're wanting to talk about.....

 

Which I find "interesting".

Edited March 3, 2017 by Cap'n kamikaze

[Capn kamikaze]

BTW, the clipped control surfaces of the AIM-120C is also part of the reason why the C has a greater range than the B.....

 

I guess that's "interesting" too.

[Frostie]

BTW, the clipped control surfaces of the AIM-120C is also part of the reason why the C has a greater range than the B.....

 

I guess that's "interesting" too.

 

The first 120C (C3) had clipped wings to fit F22 bay and improved guidance, C4 warhead, C5 bigger motor.

But this is of the beaten path.

Edited March 3, 2017 by Frostie

[Capn kamikaze]

The C-5's bigger motor, and the improved guidance from the C-3 stage (more efficient flight path) would be the others.

[Sweep]

I'm mentioning it as part of the reason why the AIM-120 has a range advantage over the AIM-7 while both missiles have very similar dimensions.

 

Its not "interesting" as you would like to characterize it.

 

There was never any version of the AIM-7 that had control surfaces as small as even the AIM-120A or B, if there was that would have helped, but..... there wasn't.

 

The R-27 has a lot more control surface area than both the AIM-120 and AIM-7, but it has a lot bigger motor.....

 

Come on, it's not that hard to follow....

 

I find it "interesting" that you would like to try to pretend I am contradicting myself, I note how you conveniently didn't mention I was comparing the AIM-7 to the AIM-120, and the major physical difference between them being the drag inducing parts, while their volume is fairly similar, it's almost as if you're picking and choosing which bits of what I have said you're wanting to talk about.....

 

Which I find "interesting".

 

Nose shape and body diameter...

[ShuRugal]

I find it "interesting" that you would like to try to pretend I am contradicting myself

 

 

That's all that could really do, change the chemical composition and design of the motor, without a major airframe redesign

 

And a major part of the reason the AIM-120 in general can fly further is because of the much smaller control surfaces' date=' which obviously means much less drag than the AIM-7.[/quote']

 

 

So, then, you are saying that the AIM-7 could really not have smaller control surfaces? Why is that? What prevents Raytheon from sticking the AIM-120 fins and servomotors on the AIM-7?

[Ktulu2]

So, then, you are saying that the AIM-7 could really not have smaller control surfaces? Why is that? What prevents Raytheon from sticking the AIM-120 fins and servomotors on the AIM-7?

 

Just an educated guess, but the size of the fins is function of the missile's mass. These fins are most likely the minimum the designers thought was possible while maintaining a good maniability. As the Sparrow is heavier than the AMRAAM, putting fins meant for a lighter missile would probably increase it's range a bit, but completely destroy it's maniability.

[Capn kamikaze]

Nose shape and body diameter...

 

Which both are not significantly different, especially compared to the difference between the surface area of the fins, in purely aerodynamic terms with the exception of the midbody fins, the AIM-120 and AIM-7 are very similar.

 

The length of each missile is the same, the body diameter difference is nearly the same, only 20mm between them, the size of the rear fins is very similar.

Edited March 5, 2017 by Cap'n kamikaze

[Capn kamikaze]

So, then, you are saying that the AIM-7 could really not have smaller control surfaces? Why is that? What prevents Raytheon from sticking the AIM-120 fins and servomotors on the AIM-7?

 

I'm saying that it didn't, not that it couldn't, and because it did not it would natually have more drag from large control surfaces as opposed to what the AIM-120 has from its much smaller surfaces.

 

If you were to put small control surfaces on the AIM-7 you would have a missile that is physically quite similar to the AIM-120.

 

If you did do that, the AIM-7 would have a longer range than it did, but no such "clipped wing" AIM-7 ever existed.

 

One reason you can't just change it so easily is that the AIM-7 is a midbody fin steered missile, and the AIM-120 is a rear fin steered missile, and because of the missiles steering fins being at the rear they will produce a control moment about the missiles COG, raising the nose, and dropping the tail.

 

The AIM-7 on the other hand produces a control moment at the middle, about the rear of the missile (the fixed fins, which naturally want to stabilise the missile) and it has to raise the nose and the midbody, which means doing that will fight against the control input, hence the much bigger fins near the middle.

Edited March 5, 2017 by Cap'n kamikaze