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Kaman Aerospace Spyglass UAV
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royabulgaf
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Re: Kaman stealthy UAV project from 1992
Can anyone advise me here? It would seem that there is no way to hide the rotor. Is there any real point in making a "stealth" coptor?
Can anyone advise me here? It would seem that there is no way to hide the rotor. Is there any real point in making a "stealth" coptor?
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Re: Kaman stealthy UAV project from 1992
Looks a little bit like a navalized UCAR, or more appropriate, as it better fits the timescale, that's
one of the seeds of the Kaman UCAR proposal.
"Is there any real point in making a "stealth" coptor?"
Why not ? The aim is, to enhance survivability, so to decrease the range, at which the UAV
can be detected, the same as with Raptor, B2 or F117. Modern rotors can be made of composites,
so having a low RCS, what's still needed then, is to decrease the RCS of the fuselage and then,
you'll have an UAV, that can maybe halve the save distance between itself and the target. In this
case, the rotor looks conventionally, so maybe not treated to any attempt to reduce the noise
signature, but at sea that may not be an important point either.
Looks a little bit like a navalized UCAR, or more appropriate, as it better fits the timescale, that's
one of the seeds of the Kaman UCAR proposal.
"Is there any real point in making a "stealth" coptor?"
Why not ? The aim is, to enhance survivability, so to decrease the range, at which the UAV
can be detected, the same as with Raptor, B2 or F117. Modern rotors can be made of composites,
so having a low RCS, what's still needed then, is to decrease the RCS of the fuselage and then,
you'll have an UAV, that can maybe halve the save distance between itself and the target. In this
case, the rotor looks conventionally, so maybe not treated to any attempt to reduce the noise
signature, but at sea that may not be an important point either.
Matej
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Re: Kaman stealthy UAV project from 1992
There are features unique to the Kaman designs that make it easier to reduce the RCS of the rotor hubs, which in other designs are primary reflectors.
royabulgaf said:
There are features unique to the Kaman designs that make it easier to reduce the RCS of the rotor hubs, which in other designs are primary reflectors.
Vivisector
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Re: Kaman stealthy UAV project from 1992
Seems to me it could be an advantage. Instead of four blades on one angle, you have two on two angles. To me it seems to follow the same faceted stealth idea as the body.
Seems to me it could be an advantage. Instead of four blades on one angle, you have two on two angles. To me it seems to follow the same faceted stealth idea as the body.
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Re: Kaman stealthy UAV project from 1992
Sure. Also if you can use composites for the rotor they may be largely radar transparent.
Sure. Also if you can use composites for the rotor they may be largely radar transparent.
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Re: Kaman stealthy UAV project from 1992
Wouldn't the same apply to props? One of the guys at work said even the most transparent of composites materials is only 90% RF transparent. I think you would still have to shape the blades, and the ideal LO shape is far from the ideal aero shape...
Wouldn't the same apply to props? One of the guys at work said even the most transparent of composites materials is only 90% RF transparent. I think you would still have to shape the blades, and the ideal LO shape is far from the ideal aero shape...
Avimimus
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Re: Kaman stealthy UAV project from 1992
Could one of you enlightened fellows explain to me why they don't simply use a larger fuselauge and ducted fans? I assume they would be less efficient due to the higher air velocity (and also perhaps the inlet design?), but they would still be much more efficient than lift jets. The UAV would be less maneuverable in a hover, but it could also potentially have lower drag in forward flight.
Could one of you enlightened fellows explain to me why they don't simply use a larger fuselauge and ducted fans? I assume they would be less efficient due to the higher air velocity (and also perhaps the inlet design?), but they would still be much more efficient than lift jets. The UAV would be less maneuverable in a hover, but it could also potentially have lower drag in forward flight.
hole in the ground
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Re: Kaman stealthy UAV project from 1992
It would depend on what is roles are. If you are expecting to spend a considerable amount of time in hover/low speed flight then big disk area i.e. rotors is what you want. If you are planning to go fast then you can look at ducted fans/lift jets.
It would depend on what is roles are. If you are expecting to spend a considerable amount of time in hover/low speed flight then big disk area i.e. rotors is what you want. If you are planning to go fast then you can look at ducted fans/lift jets.
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Re: Kaman stealthy UAV project from 1992
I think ducted fans are really heavy for the lift they produce.
It's kinda counterintuitive how you get high T/W either with open rotors, because they effect a large mass of air, or afterburning turbojets (high fuel consumption in the latter case though, even higher T/W and higher fuel consmuption with rockets btw) because their exhaust velocity is high, but there's a "valley" in between. Or so I think.
I think ducted fans are really heavy for the lift they produce.
It's kinda counterintuitive how you get high T/W either with open rotors, because they effect a large mass of air, or afterburning turbojets (high fuel consumption in the latter case though, even higher T/W and higher fuel consmuption with rockets btw) because their exhaust velocity is high, but there's a "valley" in between. Or so I think.
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Re: Kaman stealthy UAV project from 1992
Indeed, if you have something accelerating a larger mass of airflow at a lower velocity, it will be more efficient then moving a smaller mass of air at a higher velocity.
From Kohlman, page 23, for powered lift;
L=M.*Ve (eq. 2.15)
Pi=M.*((Ve2)/2) (eq. 2.16)
dividing (2.15) by (2.16) yields
L/Pi=2/Ve
Therefore, lift per unit of induced power is inversely proportional to wake/exhaust velocity.
mz said:
Indeed, if you have something accelerating a larger mass of airflow at a lower velocity, it will be more efficient then moving a smaller mass of air at a higher velocity.
From Kohlman, page 23, for powered lift;
L=M.*Ve (eq. 2.15)
Pi=M.*((Ve2)/2) (eq. 2.16)
dividing (2.15) by (2.16) yields
L/Pi=2/Ve
Therefore, lift per unit of induced power is inversely proportional to wake/exhaust velocity.
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Re: Kaman stealthy UAV project from 1992
Yeah but mass of the propulsion system is not directly related to power (fuel consumption more directly is)... large fans manipulating low speed air flows can be heavy for their thrust, when you compare to compact high speed jets...
Yeah but mass of the propulsion system is not directly related to power (fuel consumption more directly is)... large fans manipulating low speed air flows can be heavy for their thrust, when you compare to compact high speed jets...
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Re: Kaman stealthy UAV project from 1992
which is why if you don't need to hover for a long period of time you end up with high discloadings (harrier jet) and if hover is a significant fraction of your mission you end up with a low discloading (helicopter). I think UCAR requires enough low speed flight and hovering that anything smaller than a large ducted fan (a la X-22) could never be considered. Whatever you gain in installed engine weight using high discloading engines is swallowed by increased SFC, fuel flow, and ultimately required fuel weight for the mission.
OTOH, if on top of VTOL higher speeds are required, lower discloading become more appealing once again.
which is why if you don't need to hover for a long period of time you end up with high discloadings (harrier jet) and if hover is a significant fraction of your mission you end up with a low discloading (helicopter). I think UCAR requires enough low speed flight and hovering that anything smaller than a large ducted fan (a la X-22) could never be considered. Whatever you gain in installed engine weight using high discloading engines is swallowed by increased SFC, fuel flow, and ultimately required fuel weight for the mission.
OTOH, if on top of VTOL higher speeds are required, lower discloading become more appealing once again.
antigravite
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As I clean and trash some archive here is somme additional stuff...
In the early 1990s, a UAV JPO (Joint Project Office) was actively running its program(s). Up untill FY93: as of FY93, there was no successor in FY94 request. As of late august / early september 1993, it was reported that Kaman Corp offered its stealthy surveillance Spyglass UAV based on the company's prior in-house design called MMIRA (Multi-Missison Intermeshing Rotor Aircraft) which, incidentally, could also be engeneered as a MMIRA UAV variant. One possible JPO UAV project contender for shipboarding was Bell's Eagle Eye titrotor, etc. (AD:9/3/93:384)
In the early 1990s, a UAV JPO (Joint Project Office) was actively running its program(s). Up untill FY93: as of FY93, there was no successor in FY94 request. As of late august / early september 1993, it was reported that Kaman Corp offered its stealthy surveillance Spyglass UAV based on the company's prior in-house design called MMIRA (Multi-Missison Intermeshing Rotor Aircraft) which, incidentally, could also be engeneered as a MMIRA UAV variant. One possible JPO UAV project contender for shipboarding was Bell's Eagle Eye titrotor, etc. (AD:9/3/93:384)
antigravite
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Thanx alot Stargazer.Stargazer2006 said:
I just looked back at my very old notes, and highly specialized newsletters reporting back here.
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