Category: Aviation

Have Glass Equivalent Stealth Mods on Su-27 Series Fighters

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Sukhoi in RCS Test

The Russians are looking at some significant radar cross section (RCS) reductions on their Su-27 series fighters.

This is not full up stealth, you need to start at the drawing board to do that, but this is more along the line of the “Have Glass” mods done on F-16s, which involved shrouding the mechanicals of the radar systems with radar absorbent materials (RAM), using a metalized canopy to keep radar from reflecting off the cockpit contents, and some minor shaping and coatings on the engine inlets.

It’s more about making active jamming more effective, particularly in the shorter wavelengths, than it is about making an aircraft “invisible”.
The measures appear to be:

  • Masking the actuators of the radar.
  • Possible plasma cloaking of the radar.
    • This is not as outlandish as it sounds. Using plasma to cloak a complete airframe in a moving airstream is a big deal, using it under the radome, and turning it on and off to accommodate radar scans, seems more reasonable.
  • Coating the first stage fan with RAM.
  • A metalized cockpit canopy.
  • Spray on RAM on the external stores.

On the F135/F136 Debate

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Well, we have Pratt & Whitney talking to the press about how very serious they are about containing costs, even though the latest estimate shows that its price will increase to $8.3M an engine, up from $6.7 million in the most recent DoD estimate. (H/T ELP Defens(c)e Blog)

People who cover defense for a living are noting that also there is no real indicator of a cost savings by killing the F-136, it just saves a few pennies now at the expense of a few dollars later.

In any case, the DoD is in full “cover your ass” mode with Secdef Gates telling Program Executive Officer, General David Heinz, to sit down and shut up, because he is being too forthcoming about potential benefits.

We also have dueling consultants on Aviation Week’s Ares weblog, with retired general Michael Hough (GE-Rolls Royce), dsaying that there was never a competition between the engines, and retired general Mike Loh (P&W) claiming that the bidders in the program competed the engines and selected the F136.

As it turns out, General Loh is lying. The bidders for the JSF, Boeing, Lockheed-Martin, and McDonnell-Douglas, never competed the engines, they simply selected an engine for the prototypes, and since the F119, the basis of the F135 engine was already in production, they deemed it more mature for the prototype effort. (see also
here)

It should be noted that the competition is already saving money for the government, as P&W is now offering a fixed price for the first 100 of their engines, in response to the GE-Rolls Royce fixed price offer.

BTW, as to the idea that P&W has their sh%$ together in regard to cost and performance? Maybe not, because the government is sending a team of fixers to evaluate the progam, a good indication of cost and schedule problems.

Afghanistan Conditions Lead to Resurgence in Active Rotor Blade Research

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Boeing SMART Rotor


H-60 Rotor with Individual Blade Control (IBC)


DARPA Concept: Potential Settings for Active Rotor

One of the differences between rotor blades and modern aircraft wings is the relative lack of sophistication of the rotor blades. While wings have had flaps and/or slats for years, and have actively changed the shape of the wing with the benefit of fly-by-wire controls since the 1970s, the F-16 being a prime example, rotor blades have remained a single fixed airfoil with no leading or trailing edge devices.

The extreme conditions in Afghanistan, where it can be hot, and it’s always high, have led to new research into leading and trailing edge devices for helicopter rotors.

Sikorsky is testing a control system with individual blade control, a departure from the current swash plate setup used in helicopters (middle picture) in addition to testing a system with actively blade flaps, and Boeing is testing a rotor with piezoelectrically driven flaps. (top picture)

Additionally, Sikorsky is looking at some more involved, and potentially fieldable concepts:

As part of the 30-month active rotor program with AATD, Sikorsky will also study active blade slats, adaptive flight controls and a dual-frequency rotor head-mounted vibration suppression system. The study will produce the conceptual design for an H-60 [Blackhawk & Seahawk] size active rotor.

DARPA is in on this too, with its Mission Adaptive Rotor program. (the mission adaptive wing program of the early 1970s led to much of what we have now on fixed wing aircraft).

They anticipate increases in payload and range of 30-40%, reducing noise by 50%, and reducing vibration by 90%.

An-70 Moves Forward

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Click images for full size

It looks like the on-again off-again An-70 transport project is back on, with Russia and the Ukraine signing agreement to restore development to the aircraft. (see also here)

Given the problems with that Airbus A400m, being at least 2 years late, 12 tons (!) overweight, and short on promised range and cargo as a result of these problems, the AN-70 has an opening here.

They both fly at the same speed, but that Antonov flies a bit further with a 20 ton payload 6,600 km as versus 6390 km, has a bigger max payload, 47 metric tons as vs 38 metric tons, which would seem make it very competitive, though its contra-rotating props are doubtless louder, and hence more of an issue for people living near their bases in western nations.

Tekhomirov NIIP AESA radar unveiled for PAK-FA – The DEW Line

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So the Russians have now pulled the wraps off the Tikhomirov NIIP AESA radar intended for their next generation PAK-FA (see also
here)

The video says that it’s 2m in diameter, which would make it a big AESA array, but in the video, the model appears to be somewhere between 1 and 1.5 meters.

This appears to be a bit bigger than the APG-77 radar, which might be a way to improve performance relative to that radar.

Also note that the video shows some pitch and yaw on the array, which means that performance off bore sight should be pretty good.

It should do a pretty good job, even if the tech of the T/R modules is not as good, because antenna size tends to count for a lot.

Video pr0n for those of you who speak Russian:

Why the F-35 is Better Than the F-22*

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Weapons Pylons

You see, the F-35 has it, , with “it” being qualified external air to ground munitions, and can use them when the situation demands it, in places like Iraq and Afghanistan but the F-22 doesn’t. (The F-22 can carry external tanks, and AIM-132s, IIRC)

That configuration is going to be used for vibration testing.

The Raptor has theoretical provisions for external weapons stowage, but there are no plans to actually develop or qualify any sort of external stowage scheme, and the pylons are not low observable.

When you are going against a bunch of mujaheddin with an RPGs and AKs in a pick up truck, it’s nice to deliver 500 lb of boom on their heads.

*Truth be told, I think that they are both wastes of resources.

Alligator Helo to Start Radar Trials

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The Russians are starting trials with a radar roughly equivalent to the Longbow for the Kamov Ka-52 helicopter, with a roughly 30km range. (paid subscription required)

The cost for the 2nd seat and radar that were added in the upgrade from the Ka-50 is that a lot of the armor has been removed to keep weight below 10 metric tonnes.

Mostly I’m posting this for the picture, because I’ve always found the coaxial helicopters to look “cool”

Israel Looking at UAV Ambulance

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There are definitely reasons for such a craft, but I think that unmanned ambulance is not one of the better applications.

If you are evacuating someone, you want have a doctor or paramedic on site to administer things like plasma, etc., and they would likely need to monitor the patient for the trip if it is any longer than about 10 minutes, and once you have to do that, having a pilot too makes sense.

That being said, things like remote resupply would be a viable application.

Gee, It’s not Only Boeing that Has Wing Drop Issues

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When I interviewed with Lockheed-Martin Fort Worth in the late 1990s, I talked with 3 or 4 people, and they all took pot-shots at the recently discovered problems with wing drop on the then new F/A-18 E/F Super Hornet.

In tight turns in the transonic range, there would be unequal lift generated because the shock wave locations would be slightly different, and so you would get wing drop.

It now appears that that the F-35 JSF is at risk of the same behavior, at least for the extended wing CTOL carrier C model (also here), so they have put some spoilers outboard of the wing fold (see picture) just in case they cannot deal it with flap scheduling.

In the scheme of things, it’s not a particularly big deal, but considering the constant razzing the boy in Fort Worth gave Boeing over the Super Bug, it is a bit amusing.

In an Outbreak of Sanity, India Seeks to Buy, Rather Than Develop Tejas 2 Engine

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The Indian AF recently rejected proposals for foreign aid to develop the indiginous Kaveri engine from the Gas Turbine Research Establishment, and now the India’s Aeronautical Development Agency has requested proposals for complete engines from both Eurojet (EJ200) and GE (F-414) for an off the shelf proposal.

All in all, this a good move, though I am kind of surprised that the IADA is nto also looking at the Klimov RD-33, later versuions of which are in the 20,000 lb thrust range, and is already in service.

Flying Saucers News

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Nothing particularly sinister or Area 51 here, it’s just that the former GFS (Geoff’s Flying Saucer, Ltd), now Aesir, is continuing to develop their Coanda effect VTOL UAV, which uses a blower and the Coanda effect (earlier post here) to get the desired characteristics, has come up with a 1000kg payload concept, the Hoder.

You can see more pictures here, and there is a video below.

It appears to be stable, and it has an advantage over a ducted fan in that the entire bottom of the aircraft could be used to hand sensors or weapons.

Hopefully Without Rinkles

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Airbus has released pictures of its carbon fiber fuselage proof of concept models, and it looks like they are going “whole hog” on this:

“The extensive use of carbon-fibre is a significant advance: the panels, frames, window frames, clips, and door are all made from it, with a hybrid door frame structure consisting of carbon-fibre and titanium being used for the first time,” Airbus adds. The barrel also contains some metallic components in the floor and in the highly loaded “test load introduction area”.

Hopefully, they will avoid Boeing’s problems with composite structures.