You are right, Not the early models. Subsequent models yes.
but in the video it is an early model I believe.

Comparison below.

JD

http://i683.photobucket.com/albums/v...r/IMG_0438.jpg

http://i683.photobucket.com/albums/v...2164256645.jpg

SC, is that cobra head, the 540 system, the same as on the UH1L/M?

from all accounts the second hydraulic system doesn't help too much, so if you happen to loose it just at the wrong point in the turn then maybe you cant get back on track and just squash in, as he seemed to do.

I didnt see too much wrong with the turn, apart from finishing a bit too low, couldn't see the balance and all that, but there is no reason why you cant have, with the UH1's at least, the line of the horizon straight up your windscreen sky in one window ground in the other, from about that height, maybe a little higher, and still pull out of it, all in balance and without pulling excess G's.

just relooked at the video, and once he starts turning, it looks like he doesn't change angle at all, so loss of control/hydraulics is on the cards...

how do those things go doing those sort of turns at full speed? I'm normally doing them slower with a load on...

Just a couple of observations.....I flew AH-1's off and on from 1969 - 1992 as a pilot, instructor pilot, and test pilot.
A dual hydraulic failure in this case is not impossible but highly unlikely. I can only remember one that was not due to combat damage. The AH-1G thru S Models will fly acceptably on one system, the emergency procedures are really based on a single system failure becoming a dual system failure over time, so they call for a run-on landing. With the addition of the K747 (Kaman) blades there was a problem discovered with a single system not being able to overcome the aerodynamic forces for collective settings above approximately 42 lbs (75%) torque, but there were no cyclic limitations associated with these blades. There are some single system characteristics that could influence aircraft control in a steep bank that close to the ground however.

1. For a #1 SYS failure, the pedals become very stiff as the #1 SYS is the only boost on the T/R servo. Additionally you will lose YAW SCAS.

2. #2 SYS failure, you will lose PITCH & ROLL SCAS.

3. If the power applied/required was above approximately 75%, you would be faced with an involuntary collective reduction as the "down force" on the K747 blades is quite high.

4. If this aircraft was a TH-1 variant another factor is in play with a #2 SYS failure. The front seat controls in the AH-1 have a "side arm" cyclic on the right side (much like the F-16, but mechanically linked). It made it difficult for an IP to overpower a student control inputs due to a mechanical disadvantage. A fix was developed for a limited number of airframes by adding two small servos on the right side between the front and rear seat cyclics. This equalized the mechanical advantage between the crew stations, however it added an additional characteristic in the event of a #2 SYS failure. The additional servos were connected to the #2 system only, so if the #2 SYS failed, the cyclic in both crew stations became noticeably stiff as you were having to move to small "failed" servos. This might be a factor in a low level steep turn, if the aircraft involved was a "TH-1" variant, as the cyclic would become fairly stiff at the same time that PITCH/ROLL SCAS failed.

It's been a while, but I think I got all of that stuff right :)

Drop like tank, too!

A good thing those Cobras don't have wheels. :ok:

LRP:
Thanks for confirming what I'd heard many years ago about the 747 blades, and putting some numbers to it.

You're welcome. Had to reach way back in the dusty part of my head for the info, but I think it is mostly correct.

Interesting post

OUCH!
 

Ouch squared!

http://www.pprune.org/rotorheads/478...ear-crash.html

SS,

I believe the posted video by SAS is a new one of the Cobra incident a year ago!

Glad nobody got hurt.

Ouch. :eek:

Slam bang gangnam style

(try saying that with a mouth full of peas)

That´s a new video about the Top Gear Cobra´s accident, I posted it this morning here:
http://www.pprune.org/rotorheads/243...ml#post7688231

Not an ex crop sprayer then...:E

Hydraulic lock possible on the Cobra?
Although the maneuver didn´t quite seem to be this violent.

Tom

Sorry, Jack stall is what I was looking for.

Thomas

Never flew the Cobra but if memory serves me right....there is a phenomenon that can bite you.....pitch plane coupling or something like that. Perhaps an old Dog can tell us about it.

>..pitch plane coupling or something like that.

Are you going for "pitch cone coupling"?

Operators Manual: Army Model AH-1S (MOD) Helicopter - Google Books

Section 8, page 14 describes what you're looking for under the section heading:
8-38. Pitch Cone Coupling

I agree with Thone1, the maneuver doesn't seem severe enough.