Talk-Polywell.org

X-47b is not the drone I posted about. Wonder how the Avenger would fare in comparison. Cant the catapult be weighted down by some dummy weight?

IIRC, what I read those months back was talking about drones in general, not just the X-47b. It would be interesting to look afresh at that issue however.

Dummy weight. . .sounds doable. I know there are a lot of sailors would best be used as such.

(Hey, couldn't help myself. Yes I know, many of the US Navy are stand up guys and I would never insult them, but some of them serve best as lumberjacks and crash test dummies.)

More sailor jokes in 3 2 1

Concerning the steam catapults and launching drones. Currently, the T-45 Goshawk trainer jet is launched all the time and has an empty weight of 10k and max of 14K. The X-47B Avenger has an empty weight of 14K and max of 44K. (Numbers from wiki) When warming up the catapults and testing them, we shoot what are called "no-loads". Basically, exactly what it sounds like, shoot the catapult with nothing attached. The setting on the catapult when shooting no loads is higher than the setting used to shoot the T-45 on many occasions.

Conclusion, there are no limitations on today's (or soon to be yesterday's) steam catapults.

Also, there are two types of arresting gear engines for aircraft carriers: hydro-pneumatic and electric motor. The hydro-pneumatic is the current MK7 version that is on the carriers (including the French carrier!). The advanced arresting gear (AAG) is on the Ford and can be retrofitted onto the Nimitz class carriers. (A significantly easier change out than changing EM for steam in the catapults.)

I will say that trying to launch something not designed from the beginning to be launched from a carrier (like junk cars, which has been done) requires extensive modifications to the aircraft (never mind trying to recover it.) So, any drone other than the X-47B would be a costly endeavor and not worth the effort. And anything designed to be launched (and recovered) has significant design margins and can operate from any carrier currently in operation (including the French) or planned for.

R/
Former Mini Boss USS THEODORE ROOSEVELT CVN-71

I appreciate that analysis LT and there does seem to be some conflict in reports in this area, but I would note in your conclusion you hadn't considered the possibility that the drones just have lighter airframes than most planes and that's likely true. At least according to this analysis below. And I will note again, that US DOD most often misreports operational limits, power of reactors, etc., as part of their general strategy. So it is hard to know what the facts are in these cases. You certainly can't trust Wiki. There are whole forums online where Navy guys chide wiki for all the deliberate bullshit that gets posted there, despite they can't then go and correct it because the stuff is classified.

"The carrier will be capable of carrying up to 90 aircraft including the F-35C carrier variant of the Lockheed Martin Lightning II, Boeing F/A-18E/F Super Hornet, Northrop Grumman E-2D Advanced Hawkeye, Boeing EA-18G Growler electronic attack aircraft, Sikorsky MH-60R/S helicopters and future UCLASS unmanned carrier launched air vehicles systems or unmanned combat air vehicles.

The minimum weight limit is above the weight of all UAVs. An inability to launch the latest additions to the Naval Air Forces is a restriction on operations that cannot continue into the next generation of aircraft carriers. The Electromagnetic Aircraft Launch System (EMALS) provides solutions to all these problems. An electromagnetic system is more efficient, smaller, lighter, more powerful, and easier to control.

Engineers at Naval Air Engineering Station Lakehurst, N.J., work on the EMALS trough at the System Functional Display site.
Increased control means that EMALS will be able to launch both heavier and lighter aircraft than the steam catapult. Also, the use of a controlled force will reduce the stress on airframes, resulting in less maintenance and a longer lifetime for the airframe. The current system is unable to capture UAVs without damaging them due to extreme stresses on the airframe. UAVs do not have the necessary mass to drive the large hydraulic piston used to trap heavier manned planes. By using electromagnetics the energy absorption is controlled by a turbo-electric engine. This makes the trap smoother and reduces shock on airframes. Even though the system will look the same from the flight deck as its predecessor, it will be more flexible, safer, more reliable, and require less maintenance and manning.

Unlike the Nimitz, CVN-78 will have no catapult-specific restrictions on launching aircraft, but still retains four catapults, two bow and two waist. The lighter software-controlled advanced arresting gear system increases the ability to recover smaller aircraft with reduced wear. The combined contribution of those capabilities and the vessel’s higher efficiency would enable the Ford Class carrier to increase operational tempo, generating about 25 percent increase in sorties per day, compared to Nimitz-Class carriers."

http://defense-update.com/20131109_cvn- ... nched.html

Skipjack wrote:X-47b is not the drone I posted about. Wonder how the Avenger would fare in comparison. Cant the catapult be weighted down by some dummy weight?

Note there are actually 4 drones in competition in the Unmanned Carrier-Launched Surveillance and Strike program: N-G's X-47b, General Atomics Avenger C, the Boeing Phantom Ray and LockMart's Sea Ghost. None of these are air superiority craft or "dogfighters". They're all strike craft like the F-117. They don't have guns, air to air radar or the weapons to shoot at planes. The whole program is predicated around this distinction between dogfighter and ground strike that DeltaV has been selling.

I would note to you, that to fly these craft, you do have to have many more of them since they carry something like 1/4 the load of an A-6 Intruder, nor do they have the Intruder's range. Once DOD is committed to drones, I'm sure you'll see a push for bigger better ones with greater range and suddenly they'll cost as much as fighters. Funny how that happens.

Skipjack wrote:All blah, blah. F22 took years to go "online" even once it started flying. But maybe the Russian and Chinese just have a better, more efficient system? I doubt it, but you seem to imply that.

They do. It is called espionage. Dramatically shortens development time, yielding an 80% solution that gets combined with at least 20% more units built.
"Quantity has a quality all its own" - Stalin.



http://www.janes.com/article/34499/modi ... est-flight

If the reported production time-line holds, then CAC is on schedule to fulfill PLAAF General He Weirong's 9 November 2009 prediction that China's fourth-generation (fifth-generation in Western terminlogy) fighter could enter service in "8 to 10 years."

Vought TF-120 was a VTOL concept. Maybe this says something about future J-20 developments. Reason to take more time with new engine deployment.
The long view vs. the quarterly view.

The test J20 is still using the old Russian engines that are not good enough and the Chinese do not have a replacement ready, nor wont they have it for a long time.
Also if you read the article, it is clear that the design is still not fixed yet. Just think of the many iterations and problems the initial versions of the F22 have seen. 5th generation fighters are a complicated matter.
Regarding the drones: I do understand that they are not air superiority fighters, but they are serving a multitude of roles within a swarm of drones. Some of the drones will be equipped with lasers to fight incoming missiles and potentially also enemy aircraft. They wont be competitive in dog fights, but they don't have to. As I said WW2 bombers were not competitive in dogfights either, but they had small fighter escorts and otherwise just overwhelmed the Germans with their numbers. The same would work for the drones.

Ah, so you are on the engine development team. Or are you just connected enough to get intel on secret Chinese programs?

DeltaV wrote:Ah, so you are on the engine development team. Or are you just connected enough to get intel on secret Chinese programs?

No, but the Chinese have been negotiating with the Russians on buying the engines for the J20 and the Russians don't want to deliver them. It even says so in the article that you posted! The Chinese have no engines! Its always been their problem and now that they have 5th generation fighters they are even further away from the fitting generation of engines. The J31 has the same issue. Read up on it!

So you believe everything you read?

DeltaV wrote:So you believe everything you read?

Well, so do you, obviously. Let me remind you that it was you who posted that article. LOL
This is getting silly. I will come back when there is some real news again.

It is a well documented public fact that Chinese engines are crap.

As for the stresses of cat shots and wire recovery, I think that outside of Gary Brown, there is a lack of appreciation for the impact it has on an airframe, regardless of size/weight. These are extremely dynamic events that take airframes to cyclic limits. If it ain't built for it, it ain't gointa last long at it. Yes, the controllability of the launch and wire cycles is improved immensly with electromagnetic dynamics in the mix, but there is more too it than that. Just look at landing gear on a carrier aircraft compaired to a land based one. Two totally different animals. And there is more than that on the inside.

Cheers,
Not a former mini-boss, but someone who has spent some time on the flag bridge watching deck cycles.

Skipjack wrote:They might be able to get close and use their cannons (if they have one), but that will be much more difficult.

I'm just saying... And as far as you know I'm just some internet dude, but that really sounds like the sort of problem that as a former gung-ho engineering student I would dream of being tasked to. If the UAV is not evading, it definitely sounds feasible to have a semi-automated (control surfaces + flexible gun mount) aiming process for very high speed low ammunition kill solution.