PLAN Carrier Strike Group and Airwing

Re: J-15 Carrier Multirole Fighter thread

thunderchief said:

I dispute that with my own calculation above

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Well I dispute your calculations with the stats above

I hope you understand which one I trust more. Your calculations, or stats from a book specifically written from an acclaimed Russian aviation historian.

They are new design , with some improvements in technology . Compare ranges of Mig-29K and Su-33 .

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The modernized Mig-29K uses newer RD-33 variants.
A modernized Su-33 would use newer Al-31 variants as well.

Wing loading . Mig-29K has lower wing loading .

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wing loading is less important when we consider overall (i.e.: body) lift.
Btw, that is one of the common rebuttals against why calculating J-20s supposed maneuverabiltiy based off wing loading is incorrect, because it ignores body lift.

Re: J-15 Carrier Multirole Fighter thread

i have zero desire to argue here, but my position on fomin's info is "we dont know know for sure but if i had to pick, id pick those values as operational ones, meaning always at least a little headwind".

No special reason for that, it just sounds right and sounds sane and practical. Plus he talks about various loadouts for first launch positions, 26 to 28 tons, which again sounds like he's stating exact operational choices, not some theoretical limits. taking off with no headwind would constitute a theoretical take off in my book, i don't think that's ever operationally done. and even if it has to be done, in a situation where sea is calm, no wind, and ship's propulsion has broken down, the safety margins i talked about earlier may still allow for a take off, as there's no additional ship pitch or sudden wind gusts to be concerned about.

All that being said, a 20 kt headwind sounds about right as a safe, prudent operational condition. but as we know, if one adds a bit of real wind to it, it can go twice that. so theoretical loads of su33 may easely be a few tons more.

also, calculations that don't take into account whole part of the "virtual air-strip" after the ramp, that don't take into account drag (Even if it is a small part of it all) and don't take into account difference between installed and uninstalled thrust are meaningless.

Re: J-15 Carrier Multirole Fighter thread

Bltizo said:

Do your calculations include the effect of the ski jump?

Add in the ski jump, combined with 25 knots of headwind (46.3km/h), and things start looking convincing.

And of course speed the only factor in a takeoff -- lift/angle of pitch is just as important. That's the entire point of the ski jump, to enhance the latter.

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Ski jump effectively lengthens the deck . You have velocity vector pointing slightly upwards and then it moves downwards toward horizon . Therefore , by the time it goes parallel with horizon (as on carrier without ski jump ) you would accelerate a bit more . You could compensate effect of ski jump by adding few more meters to actual length of the deck . You may use around 300 m instead of 200 , for a angle of 20 degrees and speed of 200 km/h . For a 33000 kg load that would give you 243 km/h . But bear in mind I didn't calculate effects of friction and air resistance , and I assumed that engines give maximum stated thrust . As Totoro said , you need safety margins

Re: J-15 Carrier Multirole Fighter thread

thunderchief said:

Ski jump effectively lengthens the deck . You have velocity vector pointing slightly upwards and then it moves downwards toward horizon . Therefore , by the time it goes parallel with horizon (as on carrier without ski jump ) you would accelerate a bit more . You could compensate effect of ski jump by adding few more meters to actual length of the deck . You may use around 300 m instead of 200 , for a angle of 20 degrees and speed of 200 km/h . For a 33000 kg load that would give you 243 km/h . But bear in mind I didn't calculate effects of friction and air resistance , and I assumed that engines give maximum stated thrust . As Totoro said , you need safety margins

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These calculations are entirely arbitary. How can we say say that a ski jump angle of 20 degrees can be equated to an extra one hundred meters on take off??

Furthermore, do any of us know what the take off speed for a fully loaded Su-33 is anyway? Because if we dont' even have that number then any other half assed calculations won't have anything to compare with in the first place.

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Basically what I'm saying is all the calculations so far are more or less meaningless.

Re: J-15 Carrier Multirole Fighter thread

Bltizo said:

Well I dispute your calculations with the stats above

I hope you understand which one I trust more. Your calculations, or stats from a book specifically written from an acclaimed Russian aviation historian.

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Well , I don't thrust anyone and would like to see some proofs . Pictures of J-15/Su-33 taking off with full combat load would be just fine

Bltizo said:

The modernized Mig-29K uses newer RD-33 variants.
A modernized Su-33 would use newer Al-31 variants as well.

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I doubt that . But J-15 would certainly get better engines in the future . When that happens I would recalculate possible combat load .

Re: J-15 Carrier Multirole Fighter thread

Totoro said:

i have zero desire to argue here, but my position on fomin's info is "we dont know know for sure but if i had to pick, id pick those values as operational ones, meaning always at least a little headwind".

No special reason for that, it just sounds right and sounds sane and practical. Plus he talks about various loadouts for first launch positions, 26 to 28 tons, which again sounds like he's stating exact operational choices, not some theoretical limits. taking off with no headwind would constitute a theoretical take off in my book, i don't think that's ever operationally done. and even if it has to be done, in a situation where sea is calm, no wind, and ship's propulsion has broken down, the safety margins i talked about earlier may still allow for a take off, as there's no additional ship pitch or sudden wind gusts to be concerned about.

All that being said, a 20 kt headwind sounds about right as a safe, prudent operational condition. but as we know, if one adds a bit of real wind to it, it can go twice that. so theoretical loads of su33 may easely be a few tons more.

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Fair enough.

also, calculations that don't take into account whole part of the "virtual air-strip" after the ramp, that don't take into account drag (Even if it is a small part of it all) and don't take into account difference between installed and uninstalled thrust are meaningless.

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Agreed.

Re: J-15 Carrier Multirole Fighter thread

Bltizo said:

These calculations are entirely arbitary. How can we say say that a ski jump angle of 20 degrees can be equated to an extra one hundred meters on take off??

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Sin(angle) * exit_speed / (9.81m/s*s) * cos(angle)* exit_speed . With exit speed of 200km/h (calculated above for 33000 kg ) you get around 100 m . Although I don/t know exact angle of ski jump , I assumed it is 20 degrees .

Re: J-15 Carrier Multirole Fighter thread

The conclusion drawn from that calculation is flawed. Any increase in upward velocity is taken from forward velocity, which is not a performance gain. You need to look at this in terms of kinetic energy, rather than simple trigonometry.

Re: J-15 Carrier Multirole Fighter thread

Popeye's opinion on the launch ablity of the J-15.

No way no how can an airplane that large take off from a CV fully loaded and fully mission capable without the aid of a catapult.

Just my opinion. I could be wrong. But........

I will not argue with anyone.

Re: J-15 Carrier Multirole Fighter thread

thunderchief said:

Sin(angle) * exit_speed / (9.81m/s*s) * cos(angle)* exit_speed . With exit speed of 200km/h (calculated above for 33000 kg ) you get around 100 m . Although I don/t know exact angle of ski jump , I assumed it is 20 degrees .

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I could be wrong but I remember I saw it somewhere that the ski jump's angle is 14 degree.