PPRuNe Forums

PPRuNe Forums (https://www.pprune.org/)
-   Rotorheads (https://www.pprune.org/rotorheads-23/)
-   -   g loading during turns (https://www.pprune.org/rotorheads/636482-g-loading-during-turns.html)

Lonewolf_50 4th Nov 2020 02:13


Originally Posted by [email protected] (Post 10917403)
Quite why you would want to explore the g limits of a jetranger is rather beyond me:)

That was my reaction to the OP as well.
For hyperflyboy:
Fly smooth, and stay within the limits in the manual. That may sound boring, but that's what good pilots tend to do. It also saves a nice bundle of money on repairs or blade replacements.

teeteringhead 4th Nov 2020 08:22


As in Nr decay?
Yes - very marked. Although as flare effects are also strong, the Nr is (relatively!) easily recovered.

ShyTorque 4th Nov 2020 08:51


Originally Posted by teeteringhead (Post 10918449)
Yes - very marked. Although as flare effects are also strong, the Nr is (relatively!) easily recovered.

As long as the rotors are still attached to the mast...... ;)

[email protected] 4th Nov 2020 10:07

Teetering head - we also used to show this in the Gazelle from a low level 120 Kt throttle chop - a positive flare gained you a couple of hundred feet but if you pushed forward too quickly as you reached 60 kts, the Nr decayed rather quickly.

Robbo Jock 4th Nov 2020 11:08


I am wondering that if I do a 45 deg turn at max gross am I exceeding or coming close to some limitation
I would have thought that a 45 deg turn at max gross would suddenly put you at 1.4 x max gross so you'd be exceeding that one.

[email protected] 4th Nov 2020 12:26


I would have thought that a 45 deg turn at max gross would suddenly put you at 1.4 x max gross so you'd be exceeding that one
No, that's not how it works - your max gross weight limit is at take off - the addition of g loading is accounted for in the build of the aircraft as detailed in earlier posts

212man 4th Nov 2020 14:25


Originally Posted by Robbo Jock (Post 10918577)
I would have thought that a 45 deg turn at max gross would suddenly put you at 1.4 x max gross so you'd be exceeding that one.

If that was the case the RFM would have a limitation section like this:

”when departing at MAUM/MTOW, maintain straight and level flight avoiding turbulence. Once 10% fuel burn achieved turns using up to 10 degrees of bank may be carried out. After 20% fuel burn achieved angle of bank may be increased to 20 degrees.......etc”

Doesn't sound very practical does it? Hence design and certification standards (Part 27/29) have multiple safety margins built in, including load factor.

albatross 4th Nov 2020 15:03

As I recall the AS350D (Astar) RFM stated that when pulling +g the limit warning was feedback in the controls due to forces on the head overpowering the single hydraulic system. We used to demonstrate this during training. The aircraft remained fully controllable during this event and recovery was easy.
The AS355F (Twinstar) had dual hydraulic systems so they put a nice Limit Light on the panel to inform you that you were at the +G limit.

One interesting event in the Astar was if you lost hydraulics at speed and the accumulators were empty or you were silly enough to. push the button on the collective to shut them off. A very interesting climbing right turn was the result.

First action for hyd failure on an Astar was “Turn Off that ¥£&$ Horn” so you could think.

212man 4th Nov 2020 15:37

Albatross - it’s known as ‘servo transparency’ and the gazelle is the same. In fact, if you pull really hard in a Dauphin (365) it happens too - there a video around of a USCG Dolphin doing a low high speed pass with an abrupt pull up and losing control for a bit!

albatross 4th Nov 2020 15:48


Originally Posted by 212man (Post 10918700)
Albatross - it’s known as ‘servo transparency’ and the gazelle is the same. In fact, if you pull really hard in a Dauphin (365) it happens too - there a video around of a USCG Dolphin doing a low high speed pass with an abrupt pull up and losing control for a bit!

A yes “servo transparency” I should have remembered the term.
I had a couple of hydraulic failures in the Astar. A good arm exercise if you had to fly a long way home.


Robbo Jock 5th Nov 2020 16:10

Crab, 212, I should have added a smiley. I keep forgetting to do that, more's the pity. Thanks anyway for taking the trouble!

ShyTorque 5th Nov 2020 16:32


Originally Posted by [email protected] (Post 10918540)
Teetering head - we also used to show this in the Gazelle from a low level 120 Kt throttle chop - a positive flare gained you a couple of hundred feet but if you pushed forward too quickly as you reached 60 kts, the Nr decayed rather quickly.

Bearing in mind that TH was at RAF CFS(H), I’m sure he’s done more than a few of those himself..... ;)

[email protected] 5th Nov 2020 21:02


Bearing in mind that TH was at RAF CFS(H), I’m sure he’s done more than a few of those himself..... https://www.pprune.org/images/smilies/wink2.gif
when I was on the staff a colleague had to show exceptional skill turning one of those into a range auto when we chopped the throttle at 100' slightly too far from Ternhill! Just made it over the fence.:ok:

ShyTorque 6th Nov 2020 18:49

Similarly, a then colleague of mine, when we were instructing on the Gazelle, pre-briefed his student (no names mentioned to protect the guilty) about the three stages to initiate the low level engine off demo (flown by the QHI, with the throttle moved by the student).

“Identify the throttle” (student to point to it),
“Out of the gate” (student to move the throttle out of the gate),
“3-2-1, Go!” (Student to retard the throttle on the word Go).

On running in toward the airfield at very low level, my colleague got as far as “Identify the throttle”....whereupon the student promptly retarded the throttle! They landed off airfield....

[email protected] 7th Nov 2020 06:32

I also remember there was a callsign change required after some genius allocated 321Golf to someone at Shawbury:)

Not a callsign you want in the circuit when you are doing EOLs:)

After another two colleagues managed a similar 'early throttle chop' doing SCT EOLs, I changed my brief to "Close the throttle when I say GO - NOT when you think I am going to say GO":)


All times are GMT. The time now is 01:39.


Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.