CV-16, CV-17 STOBAR carrier thread (001/Liaoning, 002/Shandong)

[Blitzo]

List of requirements future aircraft is required to comply with.
That in different countries is RFP, tactical-technical task (战术技术要求）, etc.

I'm asking where did you see that there were requirements for J-XY/35 and J-15B that they were required to be capable of both CATOBAR and STOBAR launch?


Because in your last post you wrote "I am like 99.9% sure STOBAR capability was mentioned within first few points of the technical requirement for this plane." -- that made it sound like there was some technical requirements for the aircraft that we have seen before, or which you yourself have read.

Or alternatively, are you assuming that in the technical requirements for the two aircraft that there is a very high likelihood that they would've requested them to be STOBAR compatible in addition to CATOBAR?
If that is the case, then please see my last few posts where I also believe it is very likely that they did that -- but this is a matter of significant consequence that we cannot just "assume" it to be the case, but require some sort of verification.

 

[Volpler11]

However, for STOBAR launches, as part of the take off from the ski jump you will have a degree of additional vertical forces acting upwards, "pushing up" through the nose gear and forward part of the aircraft, as the aircraft takes off.

In the case of CATOBAR launches, you have horizontal forces acting forwards, as it "pull" on the nosegear and the aircraft overall.

Meaning if they want an aircraft to be both CATOBAR and STOBAR compatible, they will need to have designed the aircraft to have been reinforced in both ways.

Hmm, I have to think about this some more. But my intuition based on some quick napkin maths says that the limiting factor for a STOBAR aircraft nosegear is going to be bending moment, the same for CATOBAR.

But anyway reinforcing the nose gear to handle horizontal force will certainly have the coincidental effect of making it stronger against vertical force. Especially if the nose gear can be modelled as a column.

 

[Gloire_bb]

Or alternatively, are you assuming that in the technical requirements for the two aircraft that there is a very high likelihood that they would've requested them to be STOBAR compatible in addition to CATOBAR?
If that is the case, then please see my last few posts where I also believe it is very likely that they did that -- but this is a matter of significant consequence that we cannot just "assume" it to be the case, but require some sort of verification.

Yeah, second meaning - i.e. it's my expectation, nothing more. It's just a very logical thing to require.
I most definitely haven't seen such a document myself - I feel pretty content having tea at home.

 

[Volpler11]

I'm sure it is possible to do, but the question is how much weight does it add, and more importantly whether they've actually decided to do so.

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the best paper I found on the topic. Still reading through it but I will quote some interesting parts:

Section 2.2 Principles of the ski jump
The additional performance does not come for free, with a significant increase in landing gear loads above those of a standard take off (which are very low compared to a landing). The increase represents the energy transferred to the aircraft as it translates up the ramp; and if the angle and
curvature of the ramp are increased to obtain greater performance benefit, so are the loads. This is tolerable up to a point because the gear strength is defined by landing events and thus has the ability to accept the increased take-off loads, but loads act as an upper boundary on permissible ramp size, as illustrated in Fig. 5

Section 6.2 Loads and exit angle decision
Using the loads metric as an upper boundary achieves the most efficient ramp, as defined by imparting the maximum upward momentum without exceeding the loads metric. A range of ski jump ramps were created using the longer version of the CVS angled ramp as a template to design higher angled ramps. Figure 15 shows the nose and main peak gear loads generated.
From this it can be seen that the nose gear is well below the metric for all angles, and that a maximum exists for the main gear.
The maximum exit angle dictated by the gear loads is 12·5 degrees, slightly greater than the CVS angle, and was selected as the ramp exit angle for the following reasons:
● The loads are at their maximum tolerable threshold as defined by the metrics.
● The level of performance derived from this angle is comparable with the requirements.
● CVS ramp performance capability is achieved, but with acceptable loads.

Assuming the Chinese carrier used similar design philosophy and designed the ramp so that takeoff and landing have similar amount of load, the CATOBAR plane may not need any modification for STOBAR. At least CV-17 is supposedly have a more optimised sky jump curve with reduced angle.

 

[SAC]

I've mentioned previously here, and on my channel, that it makes a lot of sense for the J-35(?) to be able to operate off the Liaoning and Shandong. In fact, I'd be surprised if it can't operate off them. Even if that was the only change to the ships it would significantly enhance the carriers' capabilities. It would also add around 50 or so aircraft to the final production total. So for a number of reasons it seems a logical approach. It would be interesting to know if the F/A-18 E/Fs being offered to India have required modifications for Ski Jump launch.

 

[Blitzo]

I want to clarify -- of course it makes a lot of sense for J-XY/35 and J-15B to be designed to be able to operate from both CATOBAR and STOBAR carriers.
The benefits are very obvious, not only in terms of providing additional capability and longevity to the STOBAR carriers, but also in terms of general cross decking flexibility.

But this is not something we can assume as a given, but rather something that needs verification and confirmation (which is why the Shilao statement is a step in the right direction).

The extent of the consequences of whether they are compatible with STOBAR launch in addition to their baseline CATOBAR launch, is the reason why we should acknowledge there is a big empty space labelled **to be confirmed**.

 

[AndrewS]

Hmm, I have to think about this some more. But my intuition based on some quick napkin maths says that the limiting factor for a STOBAR aircraft nosegear is going to be bending moment, the same for CATOBAR.

But anyway reinforcing the nose gear to handle horizontal force will certainly have the coincidental effect of making it stronger against vertical force. Especially if the nose gear can be modelled as a column.

I previously did a back of the envelope calculation on a J-15 using the full-deck launch position without using the ski jump on a STOBAR carrier.

I ended up with the J-15 being able to takeoff at close to MTOW.

So I don't see any reason a CATOBAR capable J-15 couldn't operate from a STOBAR carrier, at least in a limited manner.

And it follows that a J-35 could operate from a STOBAR carrier in the same way.

 

[escobar]

https://twitter.com/i/web/status/1521131563203035136

 

[vincent]

Both a STOBAR and CATOBAR compatible aircraft need to be structurally reinforced to survive arrested landings -- that is the same for both of them.

However, for STOBAR launches, as part of the take off from the ski jump you will have a degree of additional vertical forces acting upwards, "pushing up" through the nose gear and forward part of the aircraft, as the aircraft takes off.

The landing of all aircrafts on carriers exerts far more vertical forces on the nose gears than the STOBAR take off. When the arresting wire pulls the airplane back, the nose of the aircraft basically slams on the deck.

 

[Blitzo]

The landing of all aircrafts on carriers exerts far more vertical forces on the nose gears than the STOBAR take off. When the arresting wire pulls the airplane back, the nose of the aircraft basically slams on the deck.

Do you think at this stage, it is safe for us to assume that the J-15B and J-XY/35 are compatible with STOBAR launch in addition to CATOBAR?

All I am asking and suggesting, is that it is something we should await to be verified, given how significant of a capability increase this would be.