• Hi Guest! Forum rules have been updated. All users please read here.

US ski jump efforts

Pyrrhic victory

This is going to hurt
Joined
Jan 31, 2008
Messages
73
Reaction score
26
"Operation Ski Jump was the test taking off of a Marine Corps YAV-8B Harrier aircraft, from a specially built ramp was constructed by the Bridge Co., 8th Engineer Support Bn., 2nd Mar. Div., Fleet Marine Force, Camp LeJuene, N.C.
Photographer's Name: McDonnell Douglas-St Louis
Location: NAVAL AIR STATIO, PATUXENT RIVER

Date Shot: 7/1/1979
VIRIN: DM-SC-82-03620"

and

"A left side view of an F-14A Tomcat aircraft taking off from a ramp, raised nine degrees, during "ski jump" feasibility tests.
Photographer's Name: PH3 Ron Vest
Location: NATC, PATUXENT RIVER

Date Shot: 9/1/1982
VIRIN: DN-ST-82-11524"
 

Attachments

  • YAV-8B.jpg
    YAV-8B.jpg
    1,016.9 KB · Views: 223
  • YAV-8B_2.JPEG
    YAV-8B_2.JPEG
    544.3 KB · Views: 197
  • F-14A_ski_jump.jpg
    F-14A_ski_jump.jpg
    1,005.2 KB · Views: 1,059

JohnR

ACCESS: Top Secret
Senior Member
Joined
Sep 8, 2006
Messages
790
Reaction score
237
Given that there is the possibility that the RN will pull out of the F-35B, and would propably adopt the CTOL F-35C as a replacement, would the C variant be able to operate from a ski jump equipped carrier?
 

JFC Fuller

ACCESS: Top Secret
Senior Member
Joined
Apr 22, 2012
Messages
2,580
Reaction score
1,022
There is no such possibility.

The CVF id designed with space saved for catapults so even if it was possible cats could be installed.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,784
Reaction score
170
In those USN ski jump trials, it was determined that all USN carrier based fixed wings could operate using ski jumps except the S-3. However, it was felt that unless the aircraft were designed as STOVL aircraft, they probably wouldn't be able to be launched as quickly as with catapults
 

Pioneer

Seek out and close with the enemy
Senior Member
Joined
May 22, 2006
Messages
1,965
Reaction score
376
Interesting photo of the Tomcat taking off from a land-based ski-jump.
I wounder what the feasibility is of a retractable ski-jump configuration as a means of a back up to get aircraft airborne/launched (granted probably at a lower fuel and weapons load!!) in case of a catapult failure/malfunction/battle damage..................??????
I know this may be tricky with the need for the catapult to run full length of the flight deck...........

P.S. I have never figured out why the USN/USMC is so reluctant to fit ski-jumps to their LHA and the likes........this would give much more range and payload capability to their AV-8B Harrier II's.
The only thing I can think of, is the USN's fear that Congress may see it reason to cutting the support and numbers of their super carriers????


Regards
Pioneer
 

archipeppe

ACCESS: Top Secret
Joined
Oct 18, 2007
Messages
1,811
Reaction score
630
No surprise to seen even F-14 airborne with sky-jump, considering that Russians regularly utilize it onboard Admiral Kuznetov to launch both Su-27 and MiG-29 (during trials).
 

Michel Van

ACCESS: Top Secret
Senior Member
Joined
Aug 13, 2007
Messages
4,980
Reaction score
1,353
and here a pictures of Sukhoi Su-33 on Admiral Kuznetsov (source Wikipedia)

Sukhoi_Su-33_on_Admiral_Kuznetsov-1.jpg


Sukhoi_Su-33_on_Admiral_Kuznetsov-2.jpg


Sukhoi_Su-33_on_Admiral_Kuznetsov-3.jpg
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,692
Reaction score
1,904
Pioneer said:
P.S. I have never figured out why the USN/USMC is so reluctant to fit ski-jumps to their LHA and the likes........this would give much more range and payload capability to their AV-8B Harrier II's.
The only thing I can think of, is the USN's fear that Congress may see it reason to cutting the support and numbers of their super carriers????

If the primary purpose of the LHAs and LHDs was to operate Harrier, putting a ramp on them would make sense. But their primary purpose is to launch assault helicopters carrying Marines and their equipment and the ramp would actually be a detriment to that mission. Adding a ramp would eliminate at least two usable deck spots, which would reduce the number of helicopters the ship could launch in a single wave. That means fewer troops landing in the initial assault, which defeats the purpose of a big-deck amphib in the first place.
 

AeroFranz

ACCESS: Top Secret
Senior Member
Joined
May 4, 2008
Messages
2,321
Reaction score
256
F-14D said:
In those USN ski jump trials, it was determined that all USN carrier based fixed wings could operate using ski jumps except the S-3. However, it was felt that unless the aircraft were designed as STOVL aircraft, they probably wouldn't be able to be launched as quickly as with catapults

just as a curiosity, what made the S-3 different in that respect?
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,784
Reaction score
170
AeroFranz said:
F-14D said:
In those USN ski jump trials, it was determined that all USN carrier based fixed wings could operate using ski jumps except the S-3. However, it was felt that unless the aircraft were designed as STOVL aircraft, they probably wouldn't be able to be launched as quickly as with catapults

just as a curiosity, what made the S-3 different in that respect?

Lack of low speed acceleration. This doesn't matter if you've got a catapult to throw you off the deck, so it wasn't considered a liability in the design.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,784
Reaction score
170
TomS said:
Pioneer said:
P.S. I have never figured out why the USN/USMC is so reluctant to fit ski-jumps to their LHA and the likes........this would give much more range and payload capability to their AV-8B Harrier II's.
The only thing I can think of, is the USN's fear that Congress may see it reason to cutting the support and numbers of their super carriers????

If the primary purpose of the LHAs and LHDs was to operate Harrier, putting a ramp on them would make sense. But their primary purpose is to launch assault helicopters carrying Marines and their equipment and the ramp would actually be a detriment to that mission. Adding a ramp would eliminate at least two usable deck spots, which would reduce the number of helicopters the ship could launch in a single wave. That means fewer troops landing in the initial assault, which defeats the purpose of a big-deck amphib in the first place.

This is by far the main reason. The AV-8B can operate for what the Marines want it to do without a ski jump, so even though the latter would enhance the Harrier's load carrying. it's not worth losing the deck spots. There is one other "political" consideration, touched on by Pioneer, although the concern was no so much the Navy fearing what Congress would do as much as the Marines fearing what the Navy might do. The Marines (at least some of them) had a fear that with ski-jumps allowing them to fly off with even more ordnance, the Navy might try and task the amphibs with some lower scale CV missions and divert them from their primary purpose so they can use the big CVs elsewhere. Like getting some extra "min-CVs" at the expens, at times, of the USMC.
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,784
Reaction score
170
Pioneer said:
Interesting photo of the Tomcat taking off from a land-based ski-jump.
I wounder what the feasibility is of a retractable ski-jump configuration as a means of a back up to get aircraft airborne/launched (granted probably at a lower fuel and weapons load!!) in case of a catapult failure/malfunction/battle damage..................??????
I know this may be tricky with the need for the catapult to run full length of the flight deck...........
It'd probably be more trouble than its worth. Very expensive, complex, slow to "convert", you couldn't repair the cats while the ski jump's in use, would add more maintenance, etc.
 

Triton

Donald McKelvy
Senior Member
Joined
Aug 14, 2009
Messages
9,719
Reaction score
818
Website
deeptowild.blogspot.com
Was the point of these ski jump efforts to determine if US Navy CTOL aircraft could operate on smaller and presumably cheaper carriers, such as the Sea Control Ship/VSTOL Support Ship, than the supercarriers equipped with catapults?
 

F-14D

I really did change my personal text
Senior Member
Joined
Oct 4, 2007
Messages
1,784
Reaction score
170
Triton said:
Was the point of these ski jump efforts to determine if US Navy CTOL aircraft could operate on smaller and presumably cheaper carriers, such as the Sea Control Ship/VSTOL Support Ship, than the supercarriers equipped with catapults?

Not so much that, because you'd still need a CVN sized ship to do CVN missions. It was more an investigation whether the next generation of carriers, or even maybe current ones, could do away with some or all catapults.
 

Abraham Gubler

ACCESS: Top Secret
Senior Member
Joined
Mar 18, 2008
Messages
3,555
Reaction score
230
Triton said:
Was the point of these ski jump efforts to determine if US Navy CTOL aircraft could operate on smaller and presumably cheaper carriers, such as the Sea Control Ship/VSTOL Support Ship, than the supercarriers equipped with catapults?

Carrier’s don’t need to be big to have catapults. Catapulting carriers under 20,000 tonnes are well proven. None of these have been built with the latest high reliability steam catapults or the next gen EML catapults so presumably they can benefit from these advances.

With conventional (ie non V/STOL) aircraft you actually need a bigger flight deck to support ski jump launching than catapult launching and hence a bigger ship. While a ski jump may lower the speed required for flight compared to a horizontal alignment (assuming equal aircraft) that speed needs to be reached by the aircraft’s own acceleration. Since this requires a run up without the benefit of external assistance (catapult) you need more space to achieve it.

You can actually combine the effect of catapulting with the skijump. However this would not work well with a typical catapult, angled landing deck carrier. It would require more length to fit the ski jump between the catapult and the bow, would be terrible for waist position catapults (bolter make sure you miss the big jump in front of you) and would also create more air disturbance burble right where the landing aircraft touches down. Since CVNs aren’t being pushed in the upper weight levels of the aircraft they are operating with the current design there is no need to add a ski jump.

Ski jumps are also a lot less safef for twin engine aircraft than catapults. With the speed provided by the catapult it is possible to survive the loss of an engine in takeoff (assuming the aircraft has the lift margins and most USN aircraft are designed for this). Without the catapulting speed boost if you lose your engine in the run up to or on the ski jump you are unlikely to stop in time, you won’t be able to fly and you’re going over the bow and then under the boat...

With V/STOL aircraft it’s an entirely different proposition as you have lift from thrust so have a lot more tolerances for takeoff speed.
 

Flying Sorcerer

ACCESS: Confidential
Joined
Jun 19, 2008
Messages
101
Reaction score
30
Abraham Gubler said:
Triton said:
Was the point of these ski jump efforts to determine if US Navy CTOL aircraft could operate on smaller and presumably cheaper carriers, such as the Sea Control Ship/VSTOL Support Ship, than the supercarriers equipped with catapults?

Carrier’s don’t need to be big to have catapults. Catapulting carriers under 20,000 tonnes are well proven. None of these have been built with the latest high reliability steam catapults or the next gen EML catapults so presumably they can benefit from these advances.

With conventional (ie non V/STOL) aircraft you actually need a bigger flight deck to support ski jump launching than catapult launching and hence a bigger ship. While a ski jump may lower the speed required for flight compared to a horizontal alignment (assuming equal aircraft) that speed needs to be reached by the aircraft’s own acceleration. Since this requires a run up without the benefit of external assistance (catapult) you need more space to achieve it.

You can actually combine the effect of catapulting with the skijump. However this would not work well with a typical catapult, angled landing deck carrier. It would require more length to fit the ski jump between the catapult and the bow, would be terrible for waist position catapults (bolter make sure you miss the big jump in front of you) and would also create more air disturbance burble right where the landing aircraft touches down. Since CVNs aren’t being pushed in the upper weight levels of the aircraft they are operating with the current design there is no need to add a ski jump.

Ski jumps are also a lot less safef for twin engine aircraft than catapults. With the speed provided by the catapult it is possible to survive the loss of an engine in takeoff (assuming the aircraft has the lift margins and most USN aircraft are designed for this). Without the catapulting speed boost if you lose your engine in the run up to or on the ski jump you are unlikely to stop in time, you won’t be able to fly and you’re going over the bow and then under the boat...

With V/STOL aircraft it’s an entirely different proposition as you have lift from thrust so have a lot more tolerances for takeoff speed.

I've often wondered why modern CVS designs don't have catapults. Is it a power generation problem given the weights of modern aircraft? How would a modern CVS powered by eg a diesel electric system generate the necessary power to run a catapult?
 

Delta Force

ACCESS: Confidential
Joined
May 23, 2013
Messages
76
Reaction score
4
There was a 1982-1986 USAF program that investigated using ski-jumps to allow aircraft to takeoff from damaged airfields. The F-16, F-15, A-10, A-7D, and F-4E were studied. Link here.
 

RP1

I see the truth in it.
Senior Member
Joined
Feb 22, 2006
Messages
473
Reaction score
279
Website
rp-one.net
I've often wondered why modern CVS designs don't have catapults. Is it a power generation problem given the weights of modern aircraft? How would a modern CVS powered by eg a diesel electric system generate the necessary power to run a catapult?


Well, the aircraft needs to be strengthened for a catapult, which is a bit different to that required for a ski-jump (mainly in the forward landing gear). More significantly, it's additional complexity for the ship. If you consider the RN CVS, the ships were very simple, with the complexity put into the aircraft. This reduces the cost of the ship as you don't need equipment or crew, and cashflow (payments per year) are frequently more important to government (and anyone else, really) than the overall cost per capability - much as we'd all like to think otherwise.


Regarding generation; The energy used by an electric catapult is provided by an Energy Storage System of some sort. The ESS is charged from generators, but if one is willing to accept a slow launch rate, then those generators can be smaller. As a quick calculation; I think a catapult of 50% efficiency would need about 2MW constant input to the ESS to launch a 20te A/C every 2 minutes, so not crazy powers.


RP1
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,692
Reaction score
1,904
Landing is also a factor. Once you adopt catapults, you need arresting gear as well. That adds even more weight and cost, and drives up ship length. The cat track can't really overlap the arresting engines, which leads to a fairly hard limit on how small a CTOL carrier can be.
 

Jemiba

ACCESS: Above Top Secret
Staff member
Top Contributor
Senior Member
Joined
Mar 11, 2006
Messages
8,295
Reaction score
1,257
TomS said:
...Once you adopt catapults, you need arresting gear as well. ...

Wasn't the RN version of the P.1154 designed for catapult launch, but would have landed vertically ?
Principally you're right, I think, but a catapult could be just a substitute for ski jump, too, used by
V/STOL, or better STOVL aircraft.
 

Flying Sorcerer

ACCESS: Confidential
Joined
Jun 19, 2008
Messages
101
Reaction score
30
I found this by "Zen" on the What if Modellers forum. I don't know how feasible it would have been but suggests that a CVS-sized CVL might have been doable.
 

Attachments

  • PA-76CVL.gif
    PA-76CVL.gif
    62 KB · Views: 163

RP1

I see the truth in it.
Senior Member
Joined
Feb 22, 2006
Messages
473
Reaction score
279
Website
rp-one.net
Meier & Gale describe a "minimum angled deck" configuration with a FD length of 813ft and full load displacement of somewhere around 30-35,000tons. Air wing would be 35 aircraft with some larger types excluded. Protection features would be limited and not all aircraft could undertake in simultaneous take-off and landing. An alternative with more restrictions and 732ft length is also illustrated.


RP1


Reference: Meier, HA & Gale, PA, "Alternatives in Aircraft Carrier Design", NEJ Feb 1977
 

RP1

I see the truth in it.
Senior Member
Joined
Feb 22, 2006
Messages
473
Reaction score
279
Website
rp-one.net
To return to topic; I'm pretty certain that one of the notional CVN(X) designs developed during a particularly imaginative study in the 1990's had a ramp in addition to catapults. Perhaps for cross-decking a STOVL JAST.


RP1
 

TomS

ACCESS: Top Secret
Senior Member
Joined
Apr 16, 2008
Messages
4,692
Reaction score
1,904
Flying Sorcerer said:
I found this by "Zen" on the What if Modellers forum. I don't know how feasible it would have been but suggests that a CVS-sized CVL might have been doable.

25-30 aircraft on 19,000 tons wasn't realistic, even in the 1970s. Aircraft have generally grown since then, but the general rule of thumb for jet carriers is still around one aircraft per thousand tons displacement (less as ship size decreases below about 20,000 tons).
 

Flying Sorcerer

ACCESS: Confidential
Joined
Jun 19, 2008
Messages
101
Reaction score
30
TomS said:
Flying Sorcerer said:
I found this by "Zen" on the What if Modellers forum. I don't know how feasible it would have been but suggests that a CVS-sized CVL might have been doable.

25-30 aircraft on 19,000 tons wasn't realistic, even in the 1970s. Aircraft have generally grown since then, but the general rule of thumb for jet carriers is still around one aircraft per thousand tons displacement (less as ship size decreases below about 20,000 tons).

I suspect the caption should have read "20-25" aircraft. So a notional air group would have been, say, 12 fighters, several helicopters and a couple of AEW aircraft; probably not a very good investment although more effective than an Invincible.
 

Flying Sorcerer

ACCESS: Confidential
Joined
Jun 19, 2008
Messages
101
Reaction score
30
RP1 said:
Meier & Gale describe a "minimum angled deck" configuration with a FD length of 813ft and full load displacement of somewhere around 30-35,000tons. Air wing would be 35 aircraft with some larger types excluded. Protection features would be limited and not all aircraft could undertake in simultaneous take-off and landing. An alternative with more restrictions and 732ft length is also illustrated.


RP1
Thanks, I'll check it out - I see it's available online.


Reference: Meier, HA & Gale, PA, "Alternatives in Aircraft Carrier Design", NEJ Feb 1977
 
Top