Do Aircraft carriers have any Aero design onsiderations?
 

Specifically, is any gain in laminar airflow across the flight deck to assist/enhance take-off and landings a consideration in the ships overall design?

8-1-24 Delete "landings" from this discussion

I would suspect not since a carrier deck, as well as an LHA has tiedowns, stays, catapault tracks, elevators and sometimes aircraft, ropes cables buildings.

Might be a bit of laminar over the bow, at speed, into a stiff wind, but it wouldn't exist very far.

On US carriers the deck is extremely flat in the takeoff portion IMO.
My thinking a carrier in many ways might operate as an inverted flat bottom car with a front splitter, optimizing smooth/proper air flow for aircraft on the deck, but my question centers around, is that intentional?
Maybe not, since the "sky Jump" carrier decks would have I suspect lousy aero features,

Looks Flat to me.

Compared to what? They have the advantage over land based runways in that they can orient into the wind.

Boat-tail a carrier?

"My thinking a carrier in many ways might operate as an inverted flat bottom car with a front splitter, optimizing smooth/proper air flow for aircraft on the deck, but my question centers around, is that intentional?"

Seems air with a non-splitter early style blunt bow would be likely cascading a lot of turbulence over the bow and would generate very unpredictable and large air currents onto the deck just as a plane was lifting off.

Your test case would be those carriers with an ski-jump ramp.

Apparently, the reason these are used is they can delete the catapult system.

Also, the comparison is to a car's underbody, which is a plenum.

No it's not, because it appears rather obvious the benefits of the ski jump solution outweigh the negatives of beneficial smooth airflow that a ski jump does not allow, and that is mainly when not able to afford or incorporate a catapult system.

The car analogy I was using here has nothing to do with a plenum, it centered mainly on the latest designs on the carrier deck acting like a car's front splitter which calms under chassis air flow leading to other attributes that apply little to a carrier, like DF, drag etc,

Whatever....

Have you actually seen or been on an operating carrier deck? Except forward of the catapult blast wall there's stuff everywhere. If they aren't launching even the catapault area has things belayed upon it. Aero isn't a prime requirement nor is smooth airflow while launching into rough weather.

I think my comment/question here went over your head,
I'm not going to bother to repeat myself. you may want to review all of what I read carefully.

carrier design
 

* the 'length' of the boat is probably the most important, as, while
'at sea' it's subject to 'pitching', with the angle of attack of the oncoming air, varying continuously with the height and separation frequency of the swells.
* depending on 'current' density altitude, each aircraft can be configured for optimum 'lift/drag' for takeoff and landing.
8) steam catapult launch systems guarantee that the plane will leave the deck at above 'stall' conditions, and power-to-weight, and rate of climb performance, specified by th NAVY, as a condition of purchase from the contractor, guarantees the under the worst-case-scenario, the the planes will make a successful takeoff.
9) the redundancy in catch-cables, 'usually' guarantees a successful landing.
10) the body of historical meteorological data in hand, allows 'known-knowns' for handling all take-offs and landings.
11) the launch deck will be 'submerged' in a turbulent boundary-layer, so any 'laminar flow' will exist only at some elevation above it, based on the distance from the 'bow' of the deck; and will be 'thickest' as the aircraft leaves the blast-diverters at initiation of launch.
12) looking at the leading edge of the USS Gerald R. Ford, there doesn't appear to be 'ANYTHING' done to address aerodynamics.

And make a 40mph headwind all by themselves. With an average natural wind speed of 18 mph off shore, it's pretty easy to make a 50+ mph steady headwind down the delck. That's not the normal goal, I think 30 mph is what they try and maintain, but they don't want crosswinds. Sometimes they would go downwind if the natural wind was over 50 mph, turn and go downwind at 20 to reduce the operational wind on the deck back to a more managed 30.

We Sometimes did a picnic on the flight deck called a "steel beach picnic". They could always get just a perfect, cooling, light breeze on the deck by adjusting speed and direction.

"...but my question centers around, is that intentional?"

Intent is hard to prove.

I agree, but not observing anything does not by itself indicate nothing intentionally aero was not addressed, and hence my original question here.

A triple negative?

I'll defer to Piotrsko on this, but I don't think the aircraft lift off, they fall off.

Whatever.

' bow wake '
 

1) I read a paper by the Office of Naval Affairs on aircraft carrier design.
The whole process is compromise between competing aspects of shipborne activities and contingencies.
2) Between the time that a design is 'frozen', construction begins, and the time when construction is completed, 'carrier compatible; aircraft may have evolved, especially with STOL/VTOL designs, which don't need as much 'runway' ( some need 'none', and takeoff velocities.
3) In 'ALL' design scenarios, the carrier must satisfy all aircraft parameters for takeoff and landing, with only one propellor in service ( as a twin-engine commercial airliner must be able to fly effectively with one 'dead' engine).
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The only other thing I saw was, in regard to a photo of the USS Kittyhawk, with a departing F-18 fighter just clearing the leading edge of its flight deck.
Both runways on this carrier have 1/4-round, leading-edge fairings, as you'd see on the bottom of an open-test-section wind tunnel nozzle at the test-section's entrance, which prevents vena-contracta entry loss formation and the attendant turbulence formation.
The 1/4-round fairing would not prevent boundary-layer buildup downstream of the 'nose', but it would mitigate 'flow separation' right at the 'end' of the runway.
Some design group clearly was thinking of the ramifications to airflow in the absence of the edge radii.

Now we are addressing the question.

So that begs the question, why don't all modern recent carriers have a 1/4 round leading edge?

Additionally, many WW2 and pre War carriers were adaptations of cruisers and battle ships, which had basically a flat flight deck extended above the main superstructure, allowing IMO significant air to flow under the flight deck and not redirect significant wake airflow onto the deck, so they likely weren't faced with the issue i am originally asking about.
Interesting about the one engine concern, which only makes sense.

There's the answer to OP's question.

Your diverters and air dams on cars must use vena contracta to limit the air going into the underbody.

' airdam vena contracta '
 

If you revisit the original video for 'Spirit', you'll see the effect with the smoke flow.
On centerline, the flow detaches to about 3" below the airdam, before it reattaches downstream onto the belly pan.
Spirit generates front downforce, and the airdam is the likely culprit.
It would have been the same for 'Spindletop' CRX, and the '64, ' screaming yellow zonkers ', Karmann-Ghia.

This pic is a good example of what I was referring to in reply #20 here that likely did not have any deck aero concerns

Are they still built that way?

Maybe seaworthiness is a concern?

No, which was my possible contention, the early carriers were because they were mostly converted battleships/cruisers for manufacturing speed and convenience and likely cost.

It's hard to respond to a 'possible contention'.

I looked at www.slashgear.com/1620347/what-happened-uss-langley-first-us-aircraft-carrier/ and cimsec.org/the-50-year-dilemma-in-aircraft-carrier-design-and-the-future-of-american-naval-aviation/ because I want to be helpful, but it's getting hard to care.

I think the catapult moots the effect of a Turbulent Boundary Layer.

I suspect it does. or the planes might be crashing into the water.

I remember a story about a hot-shot pilot who said "Watch me" and tried to hook a sharp right turn right off the flight deck. The whole thing went sideways. :eek:

' referring to '
 

This carrier also has the rounded leading edge, however, it has a vertical 'fence', which would be considered a parasitic excrescence ( unless it retracts during launch operations ), whereas the USS Kittyhawk has no fence, using catch webbing instead, should someone fall over the edge of the deck.

In all my comments shared here, I have intentionally neglected comments regarding any carrier aero design considerations towards landings, as I don't think much of a case can be made to support that consideration aero design wise. To repeat, my concern here was what was happening aero wise in the location and at the moment an aircraft actually lifts off that is affected by the bow air currents shaped by the above water design of the carrier at and forward of that lift off area. I admit this specific concern has not landed well it seems in this discussion. I also have no idea how a tailwind in reality is any part of this discussion nor is it a factor, as it is never sought on carriers, but I maybe wrong.

This is maybe pertinent but not part of my original consideration:

" Unfortunately, Royal Navy rejected his idea. The first full-deck aircraft carrier, HMS Argus, was completed in 1918 without a superstructure. As Royal Navy’s experience with Furious, which, in her original carrier configuration, had an immense superstructure in the centre of the flight deck, showed that turbulence was a significant problem for landing aircraft."
https://themaritimepost.com/2021/10/...tarboard-side/

Pertinent to "Do Aircraft carriers have any Aero design onsiderations[sic]?" but not what's happening upwind.

The other significant factor was they had the funnels sticking out the side.That didn't last.

' 1918 '
 

In 1918 we'd be looking at very 'light', cloth-covered, tail-dragger, bi-wing aircraft, of rather low stall speed , which are hard enough to master 'on land.' And it's easy to imagine the challenge to landing, on the sea, and all wind variables that could be thrown at a pilot.
Add a hundred years though, and I doubt whether or not the presence of a superstructure's 'aerodynamics' could even be felt by a pilot. The 'momentum' of carrier-ready aircraft of modern-day mass and inertias would render them oblivious to a gust that could wreck an aircraft of 1918.
The 'fuel' alone, on a 1970's NAVY F-4 Phantom, would out weigh the 'total' weight of eleven Curtiss JN-4D 'Jenny' airplanes.

I agree and mainly why landing aspects were never part of my original question.

Oh, really?

Touche.

However, On the third post (below) on this thread, my second post mere hours later from my first post, I believe I made my first attempt to narrow my threads concern to the bow's takeoff area. Not sure I ever deviated later from that primary area of concern anytime afterwards even if deck after the takeoff area has any issues with airflow.

#3 "On US carriers the deck is extremely flat in the takeoff portion IMO.
My thinking a carrier in many ways might operate as an inverted flat bottom car with a front splitter, optimizing smooth/proper air flow for aircraft on the deck, but my question centers around, is that intentional?"

Galloping goalposts. Still don't care.

' intentional '
 

I would presume that every 'feature' of any military hardware has been 'thought to death.'
'Splitters', while around since 1931 on self-powered passenger rail cars ( WESTINGHOUSE Corp. ), and around 1935 on at least one research automobile ( Koenig- Fachsenfeld's at the FKFS, Stuttgart, Germany ), would be the time frame you'd want to be looking into carrier bow design.
Cross-pollination in fluid mechanics technologies would not escape aircraft carrier design considerations.