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Newbie Joined: Jan 18, 2005 Posts: 13 Status: Offline

Hi Calhoun,

I decided to ask you this since you seem to be the most knowledgable...

I've always wondered.... How are the Raptors going to be tracked by the AWACS or any other blue force platform in order to facilitate C&C? TACAN? IFDL? LINK-16? I understand that it was decided to give the F-22s a Link-16 transmit capability a few years ago, but how did they intend to track the F-22 before that?
Does the fusion of off-board sensors include sat data? (say... the way the AARGM fuses sat data?)
Is there any plan to fit the IRST that was deleted from the original plan? Or was it deemed unnecessary? If so, is it because the AAR-56 is capable enough to take over the role in a limited fashion?
Is there any future plan for the addition of side mounted AESA arrays?
To your knowledge, how safe is Raptor from vaunted stealth killer techs like Bi-static radar tech or passive radars like Silent Sentry programs?
It seems that a new radar is being developed for the F-22. Is it just the addition of A2G radar modes to the APG-77, or a totally new derivative of the APG-77 radar?

Sorry for asking you so many questions. I understand if you can't answer due to classification issues..

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To #4: I don't know if this is the answer you were expecting but supposedly it has room for future addition of arrays to expand the field of view. I think they were planned in the original concept but abondoned to save cost. IMO, it is likely they will add this in the future...

The current production also incorporates SAR (answer to #6?)

There is JTIDS functionality that has been tested with AWACS systems and seems to work well. I imagine that will be the main source of tracking for AWACS. There are provisions for AESA and ground radar. Ground radar is coming pretty soon. IRST I believe has been dropped from the budget. Instead they are kicking around the idea of adding another CIP (Common Integrated Processor) which performs all of the fusion for the avionics along with some other functions. Hope this helped a bit.

Newbie Joined: Jan 18, 2005 Posts: 13 Status: Offline

Thanks for the replies, Pat and Cal! Ah, about the CIP thing... They need another CIP? You mean current processing power isn't sufficient? BTW, the CIP reminds me of another question - recently there were reports of overheating issues caused by the avionics when the plane is waiting on the tarmac. Is the issue resolved technically? Or did they resort to operational means of solving it like 'keep the plane in the shade', as was one of the ideas i remember in the report. Thanks!

Enthusiast Joined: Apr 19, 2005 Posts: 80 Status: Offline

Jokerblue, here are some answers:

IFDL is transmit receive but it's between F-22s only. Link 16 capability will be receive only so the AWACS will not be able to track their position via that system. They will not use A/A tacan.
Classified.
Not at this time.
The idea has been discussed but it's very unlikely due to cost and limited usefulness.
Classified and mostly theoretical.
Just the additions of A2G modes right now, but new software/capabilities will be added down the road.
The overheating issue is mostly due to software and the problems have been identified. Most of them have been fixed (or are being fixed). The aircraft doesn't have nearly the limitations that is used to in this regard.

No, the overheating issue is still valid. Currently TMS (thermal management system) is still a bit dodgy. Since the PAO(liquid coolant for avionics) lines still run through the fuel tanks, and the addition of heat from being in the sun, the F-1B temp still gets rather high. There are ways around this however. One is chilled fuel. Chilled fuel is not easy to come by, so there are two more practical measures that are usually pursued. Sun shelters help quite a bit to keep temps down. The other one, well, just get out of chocks before F-1B reaches 160*.

Quote:

4. Is there any future plan for the addition of side mounted AESA arrays?

Read my post in the 20 page <a href="f-16_forum_viewtopic-t-2874.html">thread</a> in the F/A-22 raptor category. Says that the block 30 variant will recieve side-mounted radar arrays.

Enthusiast Joined: Apr 19, 2005 Posts: 80 Status: Offline

Quote:

No, the overheating issue is still valid.

Still valid, yes. But it doesn't seem to be as bad a problem as it used to be. Maybe because it's not summer time yet?

Newbie Joined: Jan 18, 2005 Posts: 13 Status: Offline

With the problems regarding cooling, won't this severely limit the aircraft's future hardware upgradability (as in further additions of avionics, say assuming they really want to put the side-mounted arrays in future)? COnsidering that the cooling system is already facing issues right now...

Also, many detractors point to aerodynamic heating of the plane, especially during supercruise, as the chink in the armour of the Raptor. What do you guys think of the statement? Is the problem ameliorated by the aircraft's operational altitude where air is thinner, or is it reliant on the aircraft coating to reduce thermal emmision? There was a claim that the fuel (yes, fuel, though it seems ridiculous to me, so I'd think coolant instead) lines run near the leading edges of the plane where aerodynamic heating is the worst, and cools down those areas. Any truth to that?

There is excellent merit for using fuel as a coolant- it is already done on the F-16, and who-knows how many other aircraft. Exactly why or how I can't say, I don't know. In the model airplane 'glow' fuels I play with the same effect is created my the methanol evaporating. Get some on your skin, and it gives an immediate cooling effect (although this isn't the recommended way to cool off, of course). Anyway the F-16 uses fuel to cool oil for a couple of things, so there is no reason they wouldn't use it to cool stuff on the -22 as well.

Jokerblue wrote:

With the problems regarding cooling, won't this severely limit the aircraft's future hardware upgradability (as in further additions of avionics, say assuming they really want to put the side-mounted arrays in future)? COnsidering that the cooling system is already facing issues right now...

Also, many detractors point to aerodynamic heating of the plane, especially during supercruise, as the chink in the armour of the Raptor. What do you guys think of the statement? Is the problem ameliorated by the aircraft's operational altitude where air is thinner, or is it reliant on the aircraft coating to reduce thermal emmision? There was a claim that the fuel (yes, fuel, though it seems ridiculous to me, so I'd think coolant instead) lines run near the leading edges of the plane where aerodynamic heating is the worst, and cools down those areas. Any truth to that?

The avionics cooling system works pretty well, its the fuel cooling that is problematic. Future avionics upgrades shouldnt be affected by this.

There are problems with the aircraft heating up at high speeds. Some of the jets I worked at Edwards would come down with burn marks between the tails.

Newbie Joined: Jan 18, 2005 Posts: 13 Status: Offline

Burn marks?!?! Wouldn't they require a paint recoat then? Is it a real problem? Or is the solution "Dont fly too fast, dammit"?

Newbie Joined: Jan 18, 2005 Posts: 13 Status: Offline

I didn't feel that using fuel as a coolant was ridiculous because it didn't work, I felt that it was ridiculous because it seemed like a survivability hazard when one extended fuel lines all over the place. That greatly increases the chances of one of the pipes being punctured and a fire occuring. That's why I was skeptical about the claim of fuel being used.

Just to straighten it out, fuel is NOT a coolant on the Raptor. It has a special coolant called polyalphaolefin, or PAO for short. Thats what actaully cools the avionics package. The burn marks werent very large, about a half dollar in size.

Forum Veteran Joined: Nov 07, 2003 Posts: 902

calhoun wrote:

No, the overheating issue is still valid. Currently TMS (thermal management system) is still a bit dodgy. Since the PAO(liquid coolant for avionics) lines still run through the fuel tanks, and the addition of heat from being in the sun, the F-1B temp still gets rather high. There are ways around this however. One is chilled fuel. Chilled fuel is not easy to come by, so there are two more practical measures that are usually pursued. Sun shelters help quite a bit to keep temps down. The other one, well, just get out of chocks before F-1B reaches 160*.

calhoun, it is a good read on your account to the overheating issue. Sounds privileged, but I'm sure you know best.

I'm just wondering, why are these problems not identified and resolved when the Raptor was tested in ED?

regards,

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