British E-3D Sentry completes last mission before retirement

Unless all the staff of the E-3 are made redundant how exactly are we going to lose the ability to deploy wedgetail without NATO?

That’s the issue isn’t it. An acceptable gap in the context of UK and European defence but it means we can’t deploy independently of NATO. Even on something like Op Shader presumably we’re now relying on US aircraft for over-watch.

Even once we get 3 Wedgetails the RAF will do well to have more than 1 available for operations outside of the UK.

You’ve got exactly one note haven’t you?

I’m sure it will come, the technology is advancing at an incredible pace, 15 years from now such a beast will be flying.

There’s a reason Uncle Sam’s in no rush to replace the E3 in USAF service.

So only 3. That means 1 for training, 1 on standby alert to scramble for Russian bombers and 1 in maintenance/upgrading.

The ground based radars have the same weaknesses as the radars on ships being the radar horizon. This is why the commander of the QESG requested and got E-3 coverage. A high flying AEW plane provides more warning especially of low flying cruise missiles, planes, UAVs, ect.

Given that we are taking a short capability gap, I’d say it’s certain AWACS isn’t used every time.

Not really worth it.

They have missed several upgrade cycles already and using ancient computers and systems, that spares will be a massive problem for, this has its own shelf life.

If I was to take a guess, I do not know this, I would say the data has been forced on RAF when they ran out of critical bits of electronics to rob from the other airframes.

RAF signed a servicing agreement with Northrop Grumman in 2005 for the E3D after a competitive tender, ostensibly the type would then have received UK unique upgrades…these never happened and instead RAF Sentry missed out on the standard upgrades that the international E-3 fleet received. French E-3F have been through Block 30/35 and the more recent Block 40/45 upgrades. The problem is the Block 40/45 upgrade is built off work already done in 30/35, if you miss out on the former it makes the latter prohibitively complex and expensive. This is on the MOD deciding to go for a support contract that held the UK fleet separate from the international fleet standard.

3 years ago. Using AEW isn’t a common practice, and a AEW asset isn’t held on QRA. A Voyager tanker deploys when the Typhoons launch.

Don’t know. I’m not aware of any gaps in the UK’s radar coverage, even from the west. Benbecula and Portreath cover that direction.

Sorry, but this is a long one!

That’s a very good point regarding the RR embedded starter generator. When they say “beer keg”, I wonder what the real size of the engine actually is?

With radar there a lot of compromises that need to be made over the choice of the operating frequency.

The E2D’s AN/APY-9 AESA radar that operates in the UHF band (0.3 GHz to 1 GHz) for example. This means its wavelength is 1m down to 30cm. You can size an antenna to 1/4 wavelength, which means it’s 25cm down to 7.5cm. Another factor with phased arrays is that they need to have a ¼ wavelength gap between each radiating element, otherwise they will generate mutual interference. Therefore, the antenna as part of a phased array has to be chuffing large to not only to incorporate the emitters plus gaps, but to generate and handle the radiated power, not forgetting the receiver sensitivity. Due to the required size, this placed an antenna height restriction on the aircraft. As the antenna is not as tall, it compromises the beam shaping. In general, for a more rounded beam shape you need the vertical height to be at least half the horizontal length. So, the E2D’s beam ends up more like a beaver tail, but placed on its side. I suspect the actual operating frequency is closer to the top end of the band, as it means more transmitter/receiver modules (TRMs) can be squeezed into the available space. I believe due to the size of the Hawkeye aircraft, the performance of the AN/APY-9 radar is compromised.
However, a UHF radar is significantly better than a X-band radar when it comes to detection range versus power output, as longer wavelengths are less affected by free space losses (atmospheric attenuation). A UHF radar will have between 3 to 4 times the range of an X-band radar transmitting at the same effective radiated power.

As the wavelength is longer, its target resolution is rubbish compared to the X-band. It’s great for illuminating large targets but can struggle detecting very small RCS targets, especially against lots of moving background clutter like the sea. To improve its detection, it must use lots of expensive signal processing with monster algorithms. This is where they found that the radar could detect reflective back scattering and sometimes resonant reflections off smaller targets. This isn’t always guaranteed, as detectability has a lot to do with the target’s size, shape and material composition. It might struggle at detecting those Iranian suicide drones for example.

By comparison an X-band (8 to 12 GHz) radar has a wavelength of 3.75cm to 2.5cm. So, it’s antenna length at 1/4 wavelength can be 0.94cm to 0.63cm and with a 1/4 wavelength gap between each element it’s easy to see why a fighter’s AESA radar has over 1000 TRMs (Captor-E has over 1600) in the array. When a target is illuminated by a fighter’s X-band AESA radar, the radiated beam is more rounded due to the squarer array pattern, so in general more energy will hit a specific spot on the target. Therefore, crucially more can be reflected, as free space losses affect the return as well. This is partly the reason why a higher frequency radar has better target resolution. The target will appear as a blob on a basic UHF radar, whereas an X-band can (with some math’s) show an outline image of a target. You can’t use UHF radars for decent ground mapping for example.

X-band radars have their own issues. You need to use a lot more radiated power to get any decent detection range. They are also easier to counter using radar absorbent materials (RAM). This is due to the much smaller wavelength. Older RAM techniques used iron ferrite balls or wire held within a paint that was applied to an aircraft’s outer skin. They were sized according to the resonant effect of the expected threat radar’s wavelength, converting the radar emission into heat (very negligible rise in overall temperature). These only worked over a very narrow bandwidth and have been replaced with more modern materials. Although the F35’s RAM is highly classified, what is publicly known is that it uses an embedded outer skin material, that works much like an RF attenuator (big resistor) by soaking up the RF and converting it to heat. It works over a much broader band of frequencies. The rumor is it counters Upper S, C, X and most of the K band. It will have an effect with the other bands as well, but to a lesser degree.
This is where the RAF need to get smart? What does the UK require from an AEW platform? A ground-based radar can be made to be significantly more powerful than one that fits on an aircraft. It will therefore have phenomenal range looking up, but have issues due to the Earth’s curvature, creating a dead zone where threats can approach pretty closely before they are detected. An AEW platform must therefore be able to extend the radar horizon, so no sneak attacks can be made.

As I’ve highlighted it doesn’t make sense to stick with just one frequency band, as this makes it easier to counter and will have specific performance issues. Therefore, a number of bands are needed, much like the Raytheon SPY-6 dual band radar, that operates in the S and X bands. X-band is a no brainer. It can be made quite light, and they are getting more electrically efficient regarding their power supplies. It also provides the best compromise for detecting very small targets in very high clutter environments. Whereas, you really need a longer-range radar for earlier detection, preferably operating in the L or S bands. Which means you need a bigger aircraft required to carry the bigger antenna.

It is very important that you have the ability to detect a threat a long time before it can actually threaten you. We now have dedicated anti-AEW aircraft missiles such as the Russian Vympel R-37M (AA-13 Arrow), with a range around 200 miles. Even China have got in on the act will their very long-range PL-21 missile. The problem is that due to the way radar works, a radar will potentially be detected a long time before it can detect the target. With a range of 200 miles the R-37M is bang on the published max range of most available airborne X-band radars.

The use of multiple drones controlled through a mesh network is intriguing. If the drones used an AESA based radar, they could also use it as a broadband data-link, as per the F35’s MADL. This means they have a discrete method of communicating with each other and their controller. The question would be, what type of data is transmitted? Would it be raw data or processed data? By processing the data on the drone, means the signal processing is done at source, which raises costs, weight and potential cooling problems. Transmitting raw data takes up a huge amount of bandwidth, but means the radar can be made simpler. So, do you use a number of mixed sized drones carrying longwave and shortwave radars or just a large drone carrying a dual band radar, which then has the potential to be really expensive?

My preference would be a larger drone operating a dual band radar. Therefore, it would be operating outside the current anti-AEW missile range, but also has a radar capable of detecting low flying small RCS targets.

Maybe: how about on the way back!