Echster From United States of America, joined Sep 2004, 400 posts, RR: 0
Reply 1, posted (7 years 6 months 3 weeks 4 days 16 hours ago) and read 4050 times:
The blades need to be removed, IIRC. I can't exactly remember the specific parameters but part of the RFP stated the helicopter had to be mission-ready within 2 hours after arriving at its destination. The H-47 was able to meet this requirement during testing before the award was announced.
Brownout happens with every helicopter. Even the little Kiowa Warriors. Brownout is when a helicopter is taking off or landing on loose dirt and dust. The downwash from the main rotor blades creates a giant cloud of dirt that can quickly reduce visibility down to zero. If the pilot is not properly trained, he can accidentally maneuver the helicopter into an obstacle or the ground. In Iraq, I dealt with brownout conditions multiple times, every day I flew. It became a fact of life.
Whiteout is a similar concept, but occurs with snow.
I posted this in an older thread, but it applies to hear as well, so I will repost it:
On your landing approach, the dust cloud envelops you by beginning at the rear, and moving forward towards the cockpit. Your crew chief will call out the dust until brownout... "tail... exhaust... cabin door... crew window..." and POOF!** You can't see a thing in the cockpit.
The crew will attempt to perform a roll-on-landing, extending the landing as long as the terrain and obstacles allow. In the UH-60, we're looking for that rear wheel to touch down before the dust reaches the cockpit. The pilot will ease the main wheels down and apply the breaks to stop the helicopter. When the situation does not permit a roll-on-landing, you want to achieve your hover as late and as low as possible - this will keep the dust cloud from forming prematurely. As you descend vertically, your crew chief will aid you by calling out the distance to the ground, and your radar altimeter will also give your altitude above ground.
Here is a video of a CH-47 landing in Iraq. Notice how the dust develops at the rear of the helicopter, and quickly moves forward, and envelops the entire airframe just as it touches down:
Here is the same landing, but seen from the cockpit:
There are new technologies coming out that helps pilots during the scary moments when he loses sight of the ground. The USAF is fielding a new system called PhLASH:
Quote: PhLASH (photographic landing augmentation system for helicopters) takes a picture of the landing zone from as far as two football fields away before the rotors kick up the dust and sand using a high-intensity I.R. flashbulb. The black-and-white image is georectified with the onboard global positioning system, then "zoomed and panned so that it looks like what you'd see looking out of the cockpit.
PhLASH currently only installed on USAF MH-53s, displays the landing zone image in the middle of the cockpit's instrument panel directly in front of the flight engineer. During landing, the pilot focuses on the FLIR image overlaid on top of flight information (altitude, airspeed, etc.), while the engineer calls the coordinates and warns of any obscured obstacles.
Here is the system:
Here it is mounted on the nose of a MH-53:
Here is what the pilot sees. This image is 1000ft out from the landing zone:
Here it is, as the helicopter is approaching closer:
And here it is, as the helicopter touches down. You wouldn't know that there is zero visibility out the windows!
Anyway, it amazes me that the most important issue we're debating is brownout. Every helicopter is effected by brownout! And yes, different helicopters produce different size dust clouds. But the real hazard of brownout is to the pilots, and I assure you whether a small dust cloud or a large dust cloud...what airframe you are in makes no difference, because zero visibility is zero visibility!!!!
It just smacks of desperation. If this is the biggest issue the MH-47 competitors can come up with, then there's a problem.
Venus6971 From United States of America, joined Dec 2004, 1448 posts, RR: 0
Reply 4, posted (7 years 6 months 3 weeks 3 days 13 hours ago) and read 3857 times:
When I was in Keflavik Iceland back in the early 90's the Pennslyvania ANG came for the annual Viking thunder with 2 CH-47's, and 2 UH-1's it took them a whole day to get one ready to fly (CH-47)when they downladed it off a C-5. Plus they had plenty help from the 960th AWACS mx personel because we had nothing better else to do except sitting on alert or doing TCTO's on ther Rescue SQ CH-3's. I was surprised how much in common the hydro systems were the same as a 707 E-3, there both Boeings. We really enjoyed helping the ANG guys hanging rotor blades and transmissions plus learning helicopter mx. Now to the point, with the MH-60 compared to MH-47 the PG's will love the room of the MH-47 which they lost with the retirement of the CH-3, MX will hate it when it is time to deploy when the C-5 shows up, but when when reasembled mx will love it with the Boeing product.
Curt22 From United States of America, joined Jul 2007, 335 posts, RR: 0
Reply 7, posted (7 years 6 months 3 weeks 2 days 1 hour ago) and read 3624 times:
Quoting Venus6971 (Thread starter): Another question; can a CH-47 be placed into a C-5 or C-17 without having to tear off its fore and aft rotors and transmissions. That makes quick deployment susspect.
Seems Brown out has been answered very well, and there are even more miricles of modern science to mitigate brown out including what might best be described as an "Auto-Land" system that places the acft in a hover over a point on the planet by tying the auto pilot systems to the nav system then allowing the pilot to "dial down" to a full stop landing.
As for H-47 tear down...Yes, both Forward and Aft rotor pylons are required to be removed for airshipment. CSAR-X required a contender to be able to tear down for air shipment w/ in 3 hours and build up in 3 hours. All contenders met the USAF requirement. Boeing has stated they achieved this amazing feat by modifying several system conections w/ quick disconnects to speed up the process.