Design exercise: next generation carrier onboard delivery airplane for US Navy

helmutkohl said:
a somewhat related question
was there any interest in France to acquire the C-2 greyhound for either its Charles De Gaulle or future carriers?
Since it already operates the E-2, I am surprised they don't also go for the C-2.
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I vaguely remember at some point (the mid-2000s) there we rumours some might be bought. But it did not happened.
 
helmutkohl said:
what about a design that uses the coanda effect like the An-72 series or YC-14 but perhaps a bit smaller.
the An-72, if operating at short take off and landing distances, can probably do 400/600m, which should be enough for a US super carrier and thats without catapult.
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NASA/Boeing QSRA comes to mind.

VTOLicious said:
Sukhoi S-80 comes to my mind...
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DARPA Advanced Technology Tactical Transport (ATTT),developed by Burt Rutan in the late 1980s and dubbed the Special-Mission Utility Transport (SMUT) could be a suitable configuration to start with.
 

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Here is my idea for that, might be a bit too much on the traditional side and I wouldn't be to surprised if the next generation would become VTOL with some kind of hybridization.

Is start with a more basic design. Essentially, we need a rugged STOL plane for that job which should not be overly complex. My idea is producing lift in a similar way like it was done in Ecranoplanes. Therefore, I propose two engines mounted in nacelles like on the Do28

(https://en.wikipedia.org/wiki/Dornier_Do_28)

The airstream of the propellers will be partially caught in kind of a box, formed by the wing, the flaps and a vertical wall which also serves as strut for the fixed landing gear. Hopefully, this will create an air cushion which will push the plane in the air.

The engines should be combined turbines/E-engines, so that electric burst power helps for the start and can also create back up power in case of an engine failure (surly not a new idea).
 

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Nicknick said:
Here is my idea for that, might be a bit too much on the traditional side and I wouldn't be to surprised if the next generation would become VTOL with some kind of hybridization.

Is start with a more basic design. Essentially, we need a rugged STOL plane for that job which should not be overly complex. My idea is producing lift in a similar way like it was done in Ecranoplanes. Therefore, I propose two engines mounted in nacelles like on the Do28

(https://en.wikipedia.org/wiki/Dornier_Do_28)

The airstream of the propellers will be partially caught in kind of a box, formed by the wing, the flaps and a vertical wall which also serves as strut for the fixed landing gear. Hopefully, this will create an air cushion which will push the plane in the air.

The engines should be combined turbines/E-engines, so that electric burst power helps for the start and can also create back up power in case of an engine failure (surly not a new idea).
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A low wing would create some additional lift from “ground effect” … high pressure air reflected up from the deck.
A disadvantage would be the rapid change in lift as you cross the fan tail/transom.
 
Sure, but it might be a bit more difficult to blow the air under the wind (might also work well). I think the plane should have a T-tail because the two fins in my scetch wouldn't really work very well when the large flaps is lowered.
 
The conventional layout is surly more efficient for free flight, but you shouldn't underestimate the ground effekt. The Dornier seaplanes really needed the lower stub wings to produce lift by ground effect to rise the plane out of the water. Its hard to prove without CFD or a model, but I think there could be some potential.
 
It seems like this cute Herkulette is not "stol enough" to be used on a carrier deck. It might work with a catapult and wire braking, but I don't know if its feasable for a transport aircraft.
 
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My concern in that case would be as to whether it would fit below deck. For the C-27J to fit it would most likely need a complete redesign, and one may as well make a new aircraft at that point.

If I were to make a completely new aircraft, a look at some of the studies done in the 1980's may be a good place to start, as various configurations were studied.
 
Would a C-27 fit on the elevators anyway? It is substantially larger than the E-2 or C-2.

I think you have two main options:
1) A fully carrier compatible aircraft, including elevators, hangar, with hopefully some common hardware with other aircraft already in the air wing (engine, on-board systems) for easier maintainability. It would need foldable wings, and probably fins or propellers (if selected) as well. Basically a C-2 Greyhound follow-on.
Size and technical difficulties would mean a relatively small range and payload.
2) A "deck compatible" only design. Can be larger, simpler, have better range and payload. It would have less technical constraints, being maintained outside of the ship. Cons: it can't operate as an integrated part of the air wing, being on the deck for short duration only. Folding wings may be asked for nonetheless, to limit the impact on the deck operations during its use.

Just my 2 cents.
 
Manuducati said:
Would a C-27 fit on the elevators anyway? It is substantially larger than the E-2 or C-2.
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Maybe? It might fit if you hung the tail off the outer edge.



Manuducati said:
I think you have two main options:
1) A fully carrier compatible aircraft, including elevators, hangar, with hopefully some common hardware with other aircraft already in the air wing (engine, on-board systems) for easier maintainability. It would need foldable wings, and probably fins or propellers (if selected) as well. Basically a C-2 Greyhound follow-on.
Size and technical difficulties would mean a relatively small range and payload.
2) A "deck compatible" only design. Can be larger, simpler, have better range and payload. It would have less technical constraints, being maintained outside of the ship. Cons: it can't operate as an integrated part of the air wing, being on the deck for short duration only. Folding wings may be asked for nonetheless, to limit the impact on the deck operations during its use.

Just my 2 cents.
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I think the C-27J has the same engines as the E-2Ds, just different props due to vibration frequencies. Give a C-27J the 8-bladed props from the Hawkeye D and you'd be golden. Would still need the folding wings, of course.

I'm honestly not sure just how much time the CODs spend on their Host Carriers, though. A Deck Compatible Only design isn't necessarily bad if the CODs are mostly in the air away from the carrier.
 

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A second question would be whether the same airframe is to be used for AEW. If so, that would mandate that the aircraft can be stowed and serviced aboard. If it's just being used for COD, stowing and servicing (beyond fueling) may move from necessities to conveniences, which could be worked around.

Before that, what kind of payload and what are the range requirements? Does the payload include passengers? VIPs? Medical patients? Aircraft engines? Munitions?
 
1635yankee said:
A second question would be whether the same airframe is to be used for AEW. If so, that would mandate that the aircraft can be stowed and serviced aboard. If it's just being used for COD, stowing and servicing (beyond fueling) may move from necessities to conveniences, which could be worked around.

Before that, what kind of payload and what are the range requirements? Does the payload include passengers? VIPs? Medical patients? Aircraft engines? Munitions?
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I believe the primary dimensional requirement was the ability to carry an F135 engine.
 
Richard N said:
The C-3 Viking that was passed over for the CV-22: https://news.usni.org/2014/04/08/lockheed-pitching-revamped-viking-fill-carrier-cargo-tanking-roles The original Viking has performed all the roles before and with a new fuselage it could do even more, including internal carriage of an F-35 engine which the CV-22 has to sling externally.
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The CV-22 doesn't sling load an F135. A cradle was designed to hold the power unit, which is essentially the same solution LM pitched for their Viking rebuild option.
https://twitter.com/x/status/1360415029762412547
View: https://twitter.com/lfx160219/status/1360415029762412547?t=GfVvK7HmHiUBD5Wh9Cp4Rg&s=19
 
If I had a bottomless pit of money, and was willing to embark upon a new design with a very limited production run, something like a 21st century modernisation of the Boeing Model 953-517.
 
helmutkohl said:
what about a design that uses the coanda effect like the An-72 series or YC-14 but perhaps a bit smaller.
the An-72, if operating at short take off and landing distances, can probably do 400/600m, which should be enough for a US super carrier and thats without catapult.
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The anime Gasaraki showed a COD like that. Not much detail, it was basically there as the cargo hauler so you only see a couple of images of it.


red admiral said:
I wouldn't go with electrically powered. Probably twin turbogenerator mounted at mid wing / wing tip nacelles and then electric motors with props distributed along the wing. Still turning kerosene (or SAFs) into propulsive power but power transfer is electric rather than mechanical. Bit of an efficiency hit there in power transfer but probable overall net gain for this application. Want something like 5-10 MW overall which should be well within reach in the next 10 years - today it just forces a need for increased number of turbogenerators.
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You're looking at about 80% efficiency with electrical transmission, and usually around 62-75% from a mechanical transmission (friction losses and lube pump drive costs really eat your lunch)



helmutkohl said:
on a related note, there's news that the USN is considering the use of drones for onboard delivery.
i guess rather than one larger cargo plane..
smaller amount of items being delivered on more drones?
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Sure, they basically do this already, in terms of supplies from carrier to escort group via helicopter.

But one of the main jobs for the COD is hauling new engines out to the ship as a complete unit.
 
Scott Kenny said:
The anime Gasaraki showed a COD like that. Not much detail, it was basically there as the cargo hauler so you only see a couple of images of it.



You're looking at about 80% efficiency with electrical transmission, and usually around 62-75% from a mechanical transmission (friction losses and lube pump drive costs really eat your lunch)




Sure, they basically do this already, in terms of supplies from carrier to escort group via helicopter.

But one of the main jobs for the COD is hauling new engines out to the ship as a complete unit.
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When I was at Sikorsky, the gearbox efficiencies were about 95 to 98%, depending on number of gear meshes.
 
Looking back to my proposal from #48, I find the Ryan VZ-3 Vertiplan quite similar. Of course, this was intended as a true VTOL, but it also features the Props blowing under the wing, has huge flaps and end plates to prevent the air from escaping sideways.

en.wikipedia.org

Ryan VZ-3 Vertiplane - Wikipedia

en.wikipedia.org en.wikipedia.org

So, my proposal is basically a kind of a STOL version of the VTOL VZ-3.
 
1635yankee said:
When I was at Sikorsky, the gearbox efficiencies were about 95 to 98%, depending on number of gear meshes.
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We're talking a combining gearbox of some flavor, plus multiple 90deg gear boxes, plus the oil pumps to keep all those happy.

I've seen automotive equivalents running as low as 60% for a pretty high end race AWD system and sequential transmission.
 
Scott Kenny said:
We're talking a combining gearbox of some flavor, plus multiple 90deg gear boxes, plus the oil pumps to keep all those happy.

I've seen automotive equivalents running as low as 60% for a pretty high end race AWD system and sequential transmission.
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You mean combining gearboxes like in, say, large helicopters? Measured efficiencies are about 95%; see https://ntrs.nasa.gov/api/citations/19830011849/downloads/19830011849.pdf

An efficiency of 60% would be so bad that tip jet drive might actually make sense.
 
One shaft with flexible joints driving a lot of props with bevel gears, this all can be done with one step (pair of gears) between the flexible shaft going through the wing and the prop shafts. Additionally, this shaft/shafts going through the wing has to be powered somewhere, I guess with a two stage gearbox. This will end with three transmission step, each of them having about 98% efficiency, so in total it is around 94 %.

Despite the high efficiency of a mechanical system, electric power transfer offers more flexibility and redundancy, so I would prefere it under specific circumstances (https://depatisnet.dpma.de/DepatisNet/depatisnet?action=pdf&docid=DE102021003450A1&xxxfull=1). The idea of having multiple propellers in front of the wing has become quite popular, but I doubt it will be very efficient because of an highly turbulent wir flow over the wings.

By the way, my proposal could avoid that the turbulent air from the propellers will hit the wings under normal flight operation. The stub wings holding the engines could also be equiped with flaps, so that the nose down moment of the main wing flaps could be partially counteracted with positive lift in the front.
 
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Manuducati said:
Would a C-27 fit on the elevators anyway? It is substantially larger than the E-2 or C-2.
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I'm not sure a C-27 is capable of fitting below decks anyway - even with a folding fin, I suspect the fuselage might be too tall. Launch and recovery would probably be the easy bits of getting a C-27 onto a carrier.
 
Scott Kenny said:
We're talking a combining gearbox of some flavor, plus multiple 90deg gear boxes, plus the oil pumps to keep all those happy.

I've seen automotive equivalents running as low as 60% for a pretty high end race AWD system and sequential transmission.
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I guess that came out from a roller dyno test. This test methode has caused the believe, that the powertrains have immense losses, but here most of them are attributed to the rubber wheels running on small diameter rollers.
 
Nicknick said:
I guess that came out from a roller dyno test. This test methode has caused the believe, that the powertrains have immense losses, but here most of them are attributed to the rubber wheels running on small diameter rollers.
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It did. That was from Rob Dahm's crazy AWD turbo 4-rotor RX7. Made just over 1000hp at the wheels and close to 1600 at the flywheel.
 

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