STOBAR carrier takeoff performance simulation (and surprise...)

[artik]

There were recently many discussions about how STOBAR carrier perform... It is general concept that STOBAR allows only very low takeoff loads...

On the other hand some clear images of loaded MiG-29K with anti-ship missiles, fuel tanks etc...

So I decided to run some calculations on my own and refined the model for each step...

Now I has written this simulator:

http://cppcms.com/files/ah/skijump.html

You can play with Wind over deck... required stall speed and takeoff weight...

I didn't know all the parameters but in general you can see that even F-18E can takeoff at full weight from 180m strip + ramp + some wind over deck...

I played with numbers a lot and with different data from manuals, including this: https://info.publicintelligence.net/F18-EF-200.pdf
I've got research and test articles of Navy with ski-jump... Finally it seems that ski-jump works not bad at all!

i.e. with some wind speed F-18 can takeoff fully loaded, you can put data for MiG-29K for example

Thust: 18000kgf
Weight:24500kgf
Stall speed of 170 knots (also I think it is much lower - but 170 should be top boundary)

So play with it to see... how STOBAR can actually work...

And it seems to work actually very well - much better than all analysts estimate - that is why probably Indian Navy building another STOBAR carrier...

[PR3D4TOR]

Nice! 

[artik]

Now when I look at such a data it makes me rethink entire STOBAR concept...

The major drawback of STOBAR carriers is always considered low potential payload but now it seems that it isn't true...

Additionally I had found that E-2 can actually operate from ski-jump and it was used in simulations in one of Navy research papers about ski-jump - so AEW isn't an issue as it frequently mentioned in discussions and it was proposed to Indian Navy.

Interesting that Dassault Rafale was evaluated for ski-jump operations by Indian Navy (interesting what are results were).

I think biggest "Cons" of STOBAR is requirement of large strip for heavy load takeoff and inability to takeoff and land at same time when full load required - and thus smaller parking deck space.

The Pros is actually much cheaper operation and construction...


I think biggest misunderstanding of how ski-jump works is that it is frequently forgotten that the place continues to accelerate for much longer distance than the runway itself...

It makes me think that STOBAR carrier capabilities are widely - widely underestimated

[artik]

Ok...

I updated the ski-jump simulator to much more serious one:

Simulator: http://cppcms.com/files/skijump/
Flight Model: http://cppcms.com/files/skijump/#fm
F-18E/F Ski-jump simulation results: http://cppcms.com/files/skijump/#results

Changes:

1. Updated default F-18E data with correct lift to drag data (based on F-18 manuals)
2. Using acceptable AoA and stall speed values from flight testing and manuals.
3. Fixed smooth AoA change on ramp exit
4. Added detailed description of the flight model used
5. Added summary of F-18E/F results
6. Added references to the various sources


In the nutshell:

- At 66,000lb maximal takeoff weight, F-18E/F requires as low as 27-32 knots of WoD depending on AoA safety margin under 0 altitude loss.
- At 62,000lb takeoff weight (4,000lb less than maximal) it is possible to takeoff zero minimal climb rate jump condition with 27-30 knots wind over deck.
- it seems to work quite well  

[Serenity]

Honestly, I recall reading several times in publications put out by the U.S. Naval Institute that Ski-Jumps are actually quite efficient, and WOULD work perfectly well as carriers for the US, it's just a mindset thing. America likes it's super carriers, we like giant ships with 100 planes and catapults, and anyone who suggests we do anything else gets laughed it. CATOBAR is our doctrine, and we have no interest in changing. And I certainly don't mind that either! lol.

[artik]

Honestly, I recall reading several times in publications put out by the U.S. Naval Institute that Ski-Jumps are actually quite efficient, and WOULD work perfectly well as carriers for the US, it's just a mindset thing. America likes it's super carriers, we like giant ships with 100 planes and catapults, and anyone who suggests we do anything else gets laughed it. CATOBAR is our doctrine, and we have no interest in changing. And I certainly don't mind that either! lol.

Honestly, I mostly tried to show that the takeoff payload is as high as with CATOBAR.
However there other limitations for STOBAR like

- the amount of parking space on the deck (for example Vikramaditya had only12 spots not a lot for 45,000 ton carrier)
- ability to lunch and recover simultaneously
- higher dependency on the weather for WOD requirement

So there are many good reasons to use CATOBAR but the takeoff weight isn't one of them

Btw I had found  in of the articles in the references that Harrier can't takeoff with full payload without skijump from flattop, so marines basically using their Harriers without their full capabilities

[Serenity]

Honestly, I mostly tried to show that the takeoff payload is as high as with CATOBAR.
However there other limitations for STOBAR like

- the amount of parking space on the deck (for example Vikramaditya had only12 spots not a lot for 45,000 ton carrier)
- ability to lunch and recover simultaneously
- higher dependency on the weather for WOD requirement

So there are many good reasons to use CATOBAR but the takeoff weight isn't one of them

Btw I had found  in of the articles in the references that Harrier can't takeoff with full payload without skijump from flattop, so marines basically using their Harriers without their full capabilities

Which Harriers are you talking about? The british and the AV8B DO have some differences. Also, launching with a reduced fuel load and then refueling in flight is pretty common practice over here, so I imagine they launch with full weapons and just hit the tanker after takeoff for no real down-side.

[PR3D4TOR]

Needing the tanker is itself a downside. Not only is it an asset that the Marines have to call in from another service, the Marine VTOLs are supposed to be operated near the action giving the grunts on the ground air support in the quickest way possible. That's the whole point of having the VTOLs on the assault ships in the first place. Having to go to a tanker first is a huge time sink and logistical bottleneck.

[artik]

Year relying on an external tanker for an expeditionary unit is little bit to take the entire "expeditionary" from it.

BTW... First ski-jump takeoffs of the Naval HAL Tejas that were performed recently.

https://www.youtube.com/watch?v=dB73FdERNBA

Interesting that they used Harrier as a chase plane...

[PR3D4TOR]

I do like that little fighter they've made. I hope they can get it into production.