PLA AEW&C, SIGINT, EW and MPA thread

[i.e.]

Boeing/MD-st louis actually had the decency of using the same planeform lay out on -18A/B vs E/F. with the same service enviornment (carrier) with complementary requirements (fighter-attacker). thus saved a bit on development cycles.

not so for Y-7.

 

[delft]

Quite so. You get a whole new aircraft. And, doing so, I wonder if it is not better to put the antennae on the side of the fuselage and in the leading and trailing edges of the wings, getting rid of that saucer over the fuselage with its weight and drag.

 

[i.e.]

Quite so. You get a whole new aircraft. And, doing so, I wonder if it is not better to put the antennae on the side of the fuselage and in the leading and trailing edges of the wings, getting rid of that saucer over the fuselage with its weight and drag.

The problem with attennae on leading and trailing edge is that for leading edge typically the space is reserved for wing-anti-ice. for trailing edge your high lift system. your wing now is stuffed with wirings in what typically is a wet wing, not good.

antenna on side of fueslage: already done with EL/M-2075.

also these system tend to be volumnous. having them inside fueslage of a relatively tight space (carrier AWACS) may not be that good.

btw, are you from university of delft?

 

[delft]

Aircraft design at Technical University Delft, long ago.
You might use a biplane configuration and distribute antennae elements along the leading and trailing edges, giving a pretty large effective antenna.
Going back to folding biplane wings as in the old Swordfish!

 

[i.e.]

Aircraft design at Technical University Delft, long ago.
You might use a biplane configuration and distribute antennae elements along the leading and trailing edges, giving a pretty large effective antenna.
Going back to folding biplane wings as in the old Swordfish!

I work(ed) with someone from Delft. wonderful fellow.

verticle height in the attenna also matters too. more vertical elements you have the narrower the beam you can steer in vertical- more precision you can get in height data.

also as you may be aware, bi-plane is not as efficient in term of L/D given the same span and wing area if you just have a single large aspect ratio wing.
and the root bending moment is typically not the limiting factor in this day and age.

remember the "pancake" itself do generate some lift too. although much of the flow over it pretty turbulent and drag a pretty nasty wake.

attach the attenna elements over a traditional tube body supplemented by nose and tail elements (isreali's Eitam) may be the best option.

 

[delft]

For the same wing span the induced drag of the biplane is a factor of the square root of 2 smaller than for the monoplane. The biplane has two disadvantages: you have to build an extra wing and it looks old fashioned. You should disregard the second and as for the first, you avoid building that thick pancake that will probably have to be mounted on folding struts to fit into the hangar on board. Of course, I came on the biplane to give the antenna a greater height, much greater than with that pancake.
The British had an AWACS type project with the Comet airframe and antennae for and aft. It didn't look nice and it proved to be too expensive, just as the Comet derived Nimrod MR4's they are now destroying.

 

[i.e.]

For the same wing span the induced drag of the biplane is a factor of the square root of 2 smaller than for the monoplane. The biplane has two disadvantages: you have to build an extra wing and it looks old fashioned. You should disregard the second and as for the first, you avoid building that thick pancake that will probably have to be mounted on folding struts to fit into the hangar on board. Of course, I came on the biplane to give the antenna a greater height, much greater than with that pancake.
The British had an AWACS type project with the Comet airframe and antennae for and aft. It didn't look nice and it proved to be too expensive, just as the Comet derived Nimrod MR4's they are now destroying.

I think we have some mix-up in terms.

When I mentioned "given the same span and wing area " what I meant was for the bi-plane with a 2 identical wing with individual span of X and Chord of Y, the total span for the aircraft would be 2X.
if one construct a mono-plane with wing of span 2X and kept roughly the same chord of Y. the wing area would be the same. but because aspect ratio this single wing is higher your tip loss is also smaller, thus you will have a higher L/D, given the mach and alpha. now given the same wing area, the bi-wing will give a smaller wing root bending moment which will save some structure weight.

now of course I am not counting on the bi-plane's wings to be close together and advantageously affect each other thus may obtain some good pressure gradients.


Israeli's Eitam has 2 L-Band electronically steered antenna mounted outside of the body skin on each side and 2 in fore and aft bulb. not same as the swinging array Nimrod AEW has.

 

[delft]

The aircraft designer takes as the span of the wing the span of the largest wing, whether upper or lower, not the sum of the two. The biplane is really more efficient, unless you add a lot of struts and bracing wires. But producing that extra wing raises the costs significantly.
If you are prepared to pay the extra costs you may build an effective aircraft able to operate from a smaller carrier, of the size of a helicopter carrier, and so win back that extra money.You would be operating a fleet of larger carriers with fighter aircraft and smaller ones with ASW and AEW aircraft as well as helicopters and perhaps UAV and UCAV. Each carrier would be operating a reduced number of aircraft types and so reduce crew size.

 

[i.e.]

The aircraft designer takes as the span of the wing the span of the largest wing, whether upper or lower, not the sum of the two. The biplane is really more efficient, unless you add a lot of struts and bracing wires. But producing that extra wing raises the costs significantly.
If you are prepared to pay the extra costs you may build an effective aircraft able to operate from a smaller carrier, of the size of a helicopter carrier, and so win back that extra money.You would be operating a fleet of larger carriers with fighter aircraft and smaller ones with ASW and AEW aircraft as well as helicopters and perhaps UAV and UCAV. Each carrier would be operating a reduced number of aircraft types and so reduce crew size.

semantics mostly. think we know what I mean.

the second part is sea control concept. but long endurance UAVs launched from land bases can deliver the same persistence as a fleet of ships with smaller UAVs.
something like Global hawk can stay up for 28 hours. long aspect ratio wing really buys you alot

 

[delft]

Global Hawk will take many hours to arrive, while the admiral might want to have four aircraft in the air to look in several directions. You want the very long range land based UAV as well as shorter range ship based UAV's.