What was it?
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Joined: Jul 2005
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From: UK
What was it?
Just seen a helo fly overhead Bicester with what looked like crop spraying attachments either side (sticking out each side about 2/3 of the rotor disk radius).
Seems a bit too expensive an option for crop spraying so any ideas ?
Seems a bit too expensive an option for crop spraying so any ideas ?
Joined: Apr 2000
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From: West Midlands, UK.
On the Military Helicopter shown in previous posts could anyone explain what the two 'Microphone' like objects are on the end of the 'booms' that stick out from the sides of the engines(?) roughly in line with the observer's/navigator's chin?
One is upside down and the other the right way up. I just have to know.
Thank you in advance.
One is upside down and the other the right way up. I just have to know.
Thank you in advance.
Joined: May 2005
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From: UK
No worries collectivefriction... Can't help you any more than that though.
I believe they measure the wind velocity (hence their different positions). For what purpose I can't quite recall. Missile firing? (That's a technical term, by the way!) Someone will know...
Originally Posted by Cron
...could anyone explain what the two 'Microphone' like objects are on the end of the 'booms' that stick out from the sides of the engines(?) roughly in line with the observer's/navigator's chin?
Joined: Jan 2005
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From: UK
Air speed / direction for the missile control systems.
(or so I was told by the Italians at last year's WSM helidays)
I would have thought that the downwash played havoc in that place but I expect there are some very fancy electronics/computers behind the probes.
(or so I was told by the Italians at last year's WSM helidays)
I would have thought that the downwash played havoc in that place but I expect there are some very fancy electronics/computers behind the probes.
Better red than ...
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From: Appleby-in-Westmorland Cumbria England
It could have been on a bracken spraying mission (popular at this time of year). I saw an R22 thus equipped at Oban three weeks ago. Two horizontal booms & an underslung flat tank. Most perkuliar mama. (came from Thruxton, which I guess is en route from Bicester ...)
h-r
h-r
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From: Philadelphia PA
The two 'things' on the opposite sides of the pylon on the AH-64 are indeed airspeed sensors. They incorporate both pitot information and angular information to provide a relative wind signal to the fire control computer.
Since there is relatively little change the longitudinal or lateral CG with fuel burn or armament expenditure on the Apache, it's pretty easy to get accurate, repeatable information this way.
The helicopter is hovered against a known groundspeed and relative wind azimuth pace truck (this is a lot of fun) and the system is calibrated for downwash velocities and angles from the two sensors. When the system sees that in those angles and velocities in real life, it knows what the relative wind direction and speed are, and can make appropriate corrections to the fire control solution to give first round hits.
On the AH-64D, these replace the rotating low airspeed sensors on the top of the mast that featured on the AH-64A. The AH-1S had a similar single swiveling pitot tube. The HH-65 had a rotating pitot on the top of the mast. The A129 has a single swiveling pitot tube. The South African Rooivalk also had a rotating pitot tube system.
Since there is relatively little change the longitudinal or lateral CG with fuel burn or armament expenditure on the Apache, it's pretty easy to get accurate, repeatable information this way.
The helicopter is hovered against a known groundspeed and relative wind azimuth pace truck (this is a lot of fun) and the system is calibrated for downwash velocities and angles from the two sensors. When the system sees that in those angles and velocities in real life, it knows what the relative wind direction and speed are, and can make appropriate corrections to the fire control solution to give first round hits.
On the AH-64D, these replace the rotating low airspeed sensors on the top of the mast that featured on the AH-64A. The AH-1S had a similar single swiveling pitot tube. The HH-65 had a rotating pitot on the top of the mast. The A129 has a single swiveling pitot tube. The South African Rooivalk also had a rotating pitot tube system.
Joined: Dec 2001
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From: Philadelphia PA
Ah, those are easy.
The ones dangling from each missle are, in fact, dangling from the horizontal stabilizer and are static discharge wicks for continuously discharging static during flight. The one dangling from the left main tire (tahr in Texican) is also a static discharge wick - since the main wheel touches down first (hovering left wing low), it discharges the static built up during flight on touchdown. A lot of helicopters with wheels have these - some on the tailwheel, some on the mains. The tires insulate the airframe from the ground, in theory.
The ones dangling from each missle are, in fact, dangling from the horizontal stabilizer and are static discharge wicks for continuously discharging static during flight. The one dangling from the left main tire (tahr in Texican) is also a static discharge wick - since the main wheel touches down first (hovering left wing low), it discharges the static built up during flight on touchdown. A lot of helicopters with wheels have these - some on the tailwheel, some on the mains. The tires insulate the airframe from the ground, in theory.
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From: Downeast
The ones dangling from each missle are, in fact, dangling from the horizontal stabilizer and are static discharge wicks for continuously discharging static during flight. The one dangling from the left main tire (tahr in Texican) is also a static discharge wick - since the main wheel touches down first (hovering left wing low), it discharges the static built up during flight on touchdown.
With this application of active static wicks.....does one have to "earth" the aircraft when it is parked in the hangar or parked on the ramp?
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From: West Midlands, UK.
Sorry chaps, still a bit confused.
I think I understand that: fired projectiles with no inherent guidance mechanism (e.g. a bullet) need an allowance for prevailing wind for targetting.
Shawn's explanation (keep in mind I am ballistically challenged) seemed to say that the 'extra' pitots acted as sensors for the detection of the shifted downwash caused by external forces thus yielding a factor for use by the fire control solution.
If my para 2 is correct why would missiles require correction - do they not have inherent guidance?
Bit out of my depth here but indulgance appreciated.
I think I understand that: fired projectiles with no inherent guidance mechanism (e.g. a bullet) need an allowance for prevailing wind for targetting.
Shawn's explanation (keep in mind I am ballistically challenged) seemed to say that the 'extra' pitots acted as sensors for the detection of the shifted downwash caused by external forces thus yielding a factor for use by the fire control solution.
If my para 2 is correct why would missiles require correction - do they not have inherent guidance?
Bit out of my depth here but indulgance appreciated.