Helicopter Rotor Blade Radar (RODAR)
So who do you sue if something goes wrong
You and I both wonder why it hasn't been brought to market.
A kind of military explanation would go like this: The fact that it hasn't been done yet proofs that it doesn't make sense (only satisfactory if you are blessed enough not to care about explanations).
Any way, this discussion has been going in circles for a while... (no pun intended)
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This week in Britain
Half a life time ago ABC Austalia used to screen a program fronted by a Pom with a plum in her mouth called 'This week in Britain'. One memorable episode featured a Wessex with microwaves piped up the rotor mast to rotor blades modified as antennas. I recall a detailed image of London on a CRT in which the Thames was clearly visible.
How you could fiddle with a helo power plant to the extent that the main drive shaft out of the gearbox became a waveguide & still keep the machine air worthy is just awesom I reckon.
How you could fiddle with a helo power plant to the extent that the main drive shaft out of the gearbox became a waveguide & still keep the machine air worthy is just awesom I reckon.
There will also be doppler shift to deal with, as the antenna is not fixed
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Quote:
Originally Posted by ion_berkley View Post
OK I'll bite since I design RADAR stuff amongst other things.
A quick "back of the fag packet calculation" gives me the following:
Lynx rotor disc diameter (as an example): 12.8M
Lynx blade tip speed: 700 feet/sec = ~ 214M/S
Centripetal Acceleration = (v*v)/r = (214 * 214)/6.4 = 7155 M/S^2
i.e 70g constant acceleration.
Err , maybe need to get your cigarette packet checked
Is 7155m/s^2 ~= 70g ? (More like: 700g)
i can understand that valves might have an issue at 700g, but why would a chip care about being at 700g ?
Originally Posted by ion_berkley View Post
OK I'll bite since I design RADAR stuff amongst other things.
A quick "back of the fag packet calculation" gives me the following:
Lynx rotor disc diameter (as an example): 12.8M
Lynx blade tip speed: 700 feet/sec = ~ 214M/S
Centripetal Acceleration = (v*v)/r = (214 * 214)/6.4 = 7155 M/S^2
i.e 70g constant acceleration.
Err , maybe need to get your cigarette packet checked
Is 7155m/s^2 ~= 70g ? (More like: 700g)
i can understand that valves might have an issue at 700g, but why would a chip care about being at 700g ?
You asked about acceleration and chips...well likely the chips themselves are not the weakest link, but I can only imagine that such cyclical stress would be very detrimental to reliability and lifetime. Whats trickier is keeping everything rigid and planar, bearing in mind all this technology is generally optimized for its electrical qualities rather than mechanical, unlike the composites and alloys used in blade construction, many of the components used in these types of circuits contain fine, hair line filaments of wire or resonating crystals internally for example. Just because R&D has worked out how to put a guidance system into an artillery shell, doesn't make that technology commodity, cheap, or even attractive. At the end of the day, whilst "cost is no obstacle" technologies had there place in the military of the 50's and 60's, thats not the case today.
As for patents, well I have a bunch. I doubt many of the protected technologies in them will ever see commercial success, but its a form of insurance policy when it all occasionally works out.
I think it boils down to this. If you really have an application that requires this level of RADAR functionality then you build it in the contemporary AESA style, conformal with the structure of the aircraft. I've got to believe that the material and mechanical technology that goes into blade design is already difficult enough that it would require enormous justification to add this type of complexity even before we consider how much harder it makes the job of the RADAR design team.
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@ion berkley,
My only hope here is, with the exponential advances in computer, material, mechanical and electrical sciences that a system which could drastically improve helicopter operation safety isn't left to collect dust on a back shelf somewhere.
Other than obvious military applications I think such a system would benefit the HEMS and SAR industry tremendously.
You never know, there could be some prodigal wiz kids at MIT right now reading this thinking to themselves, "I've got the key to make this work".
Since any development I could find ceased some years back maybe it's time to revisit the concept?
My only hope here is, with the exponential advances in computer, material, mechanical and electrical sciences that a system which could drastically improve helicopter operation safety isn't left to collect dust on a back shelf somewhere.
Other than obvious military applications I think such a system would benefit the HEMS and SAR industry tremendously.
You never know, there could be some prodigal wiz kids at MIT right now reading this thinking to themselves, "I've got the key to make this work".
Since any development I could find ceased some years back maybe it's time to revisit the concept?
Last edited by SeaMac; 19th May 2015 at 23:29.
