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"Engine Chop" a no no button?


Rhinozherous

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Reading thru the manual and found the Engine chop button... when in flight this button seems to be a very "no no" button as it brings the engine to idle in a very fast way it seems.

Which situation will make a sane pilot push this button? 😄 Or is it only for ground?

Thank you! 


Edited by Rhinozherous

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1 hour ago, Rhinozherous said:

Reading thru the manual and found the Engine chop button... when in flight this button seems to be a very "no no" button as it brings the engine to idle in a very fast way it seems.

Which situation will make a sane pilot push this button? 😄 Or is it only for ground?

Thank you! 

 

You use it on air too its an emergency button 

1 hour ago, Rhinozherous said:

Edited by MertTunç
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  • 2 months later...

I think CHOP cuts fuel and closes throttle to engines, and disconnects rotor from gearbox. Probably the closest thing Apache has to fixed wing ejection. You lost tail rotor, or both engines are on fire , missile or AAA deprived your Apache of its boom.  It is , perhaps, faster then manually throttling back and shutting down the engines. In RL, and this is from 'Chickenhawk' memoir, in U.S. Army aviation school, trainees are taught , in case of loss of power in fwd flight, immediately , drop sling load (or drop stores), turn into wind, cut throttle(CHOP power), collective all the way down, and enter autorotation. In autorotation maintain attitude and collective to keep rotor RPM in 'green', at about 50-70 feet (treetop) cyclic back aft to 30 deg, collective slight up, collective fwd to bring nose to zero pitch, collective UP untill helicopter skids to halt. During training, the instructor was always reinforcing trainee that whenever in flight, rotary pilot should always be, cognizant of wind direction, selecting aimpoint for autorot landing, as if he would loose engine at that moment. During training and testing, instructor would surprise trainee with "LOST ENGINE", and then evaluate pilot on how he (or she today) performed emergency autorotation. The harder training and test was Loss Of Tailrotor Effectiveness, on approach to landing zone. Becouse how pilot handled LTE is based on helicopter altitude above ground, fwd speed, gross weight. Hardest was LTE or LOST ENGINE in confined area operations.  

P.S. Does Apache even has sling load capability for those rare times ? I don't think it does. However Israelis on the AH-64A/D Petan (Python in Hebrew), and British Army equipped their Westland Apaches with safety rope attachments on cheeks, allowing Apache to perform emergency extraction or rescue of personnel. The personnel would then sit on the cheek, holding for dear life.

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  • ED Team
15 minutes ago, DmitriKozlowsky said:

snip

It doesn't shut down the engines, but it does reduce the fuel flow to minimum required to IDLE the engines. There is no actual "disconnecting the rotor from the gearbox" that is even possible in the AH-64. Overrunning clutches on the main transmission allow the powertrain to spin faster than the input drives coming from the engines, so if one or both of the engines are idling it won't necessarily bring down the rotor RPMs provided there is some other form of drive keeping them at speed (ie the other engine or an autorotation).

Also keep in mind that a lot of what you quoted was in reference to single-engine helicopters, and the considerations of such airframe types. Regardless of how many engines or how much power margins you may have, a good aviator is always cognizant of the winds, especially when operating low and over the terrain.

See my post here:

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Afterburners are for wussies...hang around the battlefield and dodge tracers like a man.
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Good stuff. Chickenhawk is memoir of UH-1C/D/H Warrant Officer aviator. I figure that rotary is rotary and thus lessons taught carry from one type to another . For myself, in DCS, I have a bit of problem of instinctively knowing wind direction at any one time, unless I see some clue. Smoke is #1, windsocks if close to one, flags, and least usefull is the darn weathervane slip indicator. In Gazelle that string is useful, because it is visible. In KA-50 weathervane on nose is difficult to make out what its doing, same in AV-8B. In UH-1H, have to go by instrument sideslip indicator. AH-64D has two, one just aft of engine exaust, but what I should be looking for on HUD or instruments, I am not there yet. Without dynamic weather, take brief wind direction, then subtract 180 (if over 180), or add 180 (if less then 180), and that the direction to point the nose to land helicopter into the wind.

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1 hour ago, DmitriKozlowsky said:

Chickenhawk is memoir of UH-1C/D/H Warrant Officer aviator. I figure that rotary is rotary and thus lessons taught carry from one type to another . For myself, in DCS, I have a bit of problem of instinctively knowing wind direction at any one time, unless I see some clue.

I know the book, almost every aviator in US Army aviation does. But not all rotary equals another. For example, engine failure in a single-engine helicopter = autorotation. Engine failure in a multi-engine helicopter = substantial power loss, but not an immediate landing within autorotational glide distance. But comparing a single-engine Vietnam-era helicopter to a modern day multi-engine helicopter is very different in a discussion about being on guard for engine trouble and always being on the lookout for places to autorotate to. Especially when you consider how much more reliable turbine engines in the modern helicopters are to their older counterparts.

This can also be seen in some of the fallacies related to the F-35 debates. One of the common clichés we see thrown out there is that the F-35C for the Navy is dangerous due to the fact it has only one engine, with no redundancy for over-water operations.  Well, historically the Navy has operated single-engine aircraft off of carriers for much more of it's existence than not. Only in the past several decades has the US Navy operated exclusively multi-engine aircraft. Further, the reliability of engines in today's aviation technology is leaps and bounds what it was in the Cold War. Even further, a number of multi-engine aircraft that suffered catastrophic engine failures actually lost both engines due to the engine placement side-by-side (cough F-4 Phantom).

This is all off topic, but the point I'm trying to make is that often people make comparisons based on singular variables to prove a point, but often such comparisons are very one-dimensional and inaccurate, and don't adequately examine all the variables that affect the discussion.

On the topic of wind, the best indicators of wind is by comparing the airspeed with the ground speed in the HDU symbology, and looking at the Velocity Vector for your ground track. Wind is less an issue for engine malfunction, and more a consideration for power management. If you can stay above 30 knots airspeed the rotor system is much more efficient due to Effective Translational Lift, and this requires less power to maintain altitude. If you are flying at 35 knots ground speed across the treetops with a 20 knot tail wind, you are essentially hovering out-of-ground-effect (OGE) within the air mass because your airspeed is 15 knots. This requires substantially more power and fuel burn, and can impact your maneuverability and options when reacting to a threat. Or you can be in a low-speed orbit at low altitude, and as you turn with the wind direction that tail wind will sap your airspeed and you will encounter an unexpected descent rate if you aren't ready for it, not to mention the weathervane effects on the vertical tail can cause a spike in torque when you stomp on the left rudder to counter a right yaw.

18 hours ago, DmitriKozlowsky said:

However Israelis on the AH-64A/D Petan (Python in Hebrew), and British Army equipped their Westland Apaches with safety rope attachments on cheeks, allowing Apache to perform emergency extraction or rescue of personnel.

Those aren't safety rope attachments, those are just the handholds that are installed on all Apaches for personnel to climb around on the exterior for maintenance or pre-flight checks. It just provides a convenient place to hook a carabiner and lanyard for emergency extraction of personnel. But some of those handholds aren't rated to hold a person's entire body weight, which is why it's an emergency procedure. Many countries have this procedure, not just Israel and UK.


Edited by Raptor9
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Afterburners are for wussies...hang around the battlefield and dodge tracers like a man.
DCS Rotor-Head

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vor 1 Stunde schrieb Raptor9:

Those aren't safety rope attachments, those are just the handholds that are installed on all Apaches for personnel to climb around on the exterior for maintenance or pre-flight checks. It just provides a convenient place to hook a carabiner and lanyard for emergency extraction of personnel. But some of those handholds aren't rated to hold a person's entire body weight, which is why it's an emergency procedure. Many countries have this procedure, not just Israel and UK.

 

I will be highly off topic here, but i was just remembered on one day during an exercise. For emergency extraction 2 guys were hooked under a german (eurocopter) Tiger. At the "front wheels", so to say. That looked fun 😀 Though the helo would just hover for some meter, staying at "jump-able" height. After all it was just an exer.

 

We had a saying, roughly translated:

Where there is need - one will find a way.

Thank you for bringing back memories @Raptor9🙂

K

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1 hour ago, Kharrn said:

I will be highly off topic here, but i was just remembered on one day during an exercise. For emergency extraction 2 guys were hooked under a german (eurocopter) Tiger. At the "front wheels", so to say. That looked fun 😀 Though the helo would just hover for some meter, staying at "jump-able" height. After all it was just an exer.

 

We had a saying, roughly translated:

Where there is need - one will find a way.

Thank you for bringing back memories @Raptor9🙂

K

IDF Cobras once or twice extracted individual IDF infantry in Lebannon by having the guys stand on or hang on to skids. In AfPak, Royal Army/RAF joint Apache force rescued Royal Marine Commando in fashion of sitting on cheek of AH-64 (Westland). I do not know if US.Army 160th SOAR ever done this type of emergency extraction , but I doubt it. SOAR does not have any AH-64 assigned to it per TOE, although I imagine those assets can be brought under SOAR command for mission or campaign. AH-6 Little Bird uses side boards to seat 4 Rangers or SFG-ODD operators.

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1 hour ago, DmitriKozlowsky said:

I do not know if US.Army 160th SOAR ever done this type of emergency extraction

Regular US Army units have done it and long before the RAF ever did. There was at least one case in Desert Storm and multiple cases in the past 20 years during OIF and OEF.

https://www.myplainview.com/news/article/Apache-pilot-recommended-for-medal-after-rescuing-8921053.php

https://www.nationalguard.mil/News/Article-View/Article/573012/apache-pilots-save-critically-wounded-soldier-with-unorthodox-evacuation/

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I'm a bit puzzled as you guys seem to be saying that the "Chop" actually does something. I have tried several times in flight:
1. Open the Guard
2. Chop button depress
I do not see anything changing in the Engine page, and I do not see the chopper losing speed. It just carries on at same altitude and speed.


Edited by LeCuvier

LeCuvier

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On 6/3/2022 at 9:38 PM, DmitriKozlowsky said:

I think CHOP cuts fuel and closes throttle to engines, and disconnects rotor from gearbox. Probably the closest thing Apache has to fixed wing ejection. (...)

3x wrong. IRL, when you press Chop button, both engine are just reduced to idle. (How and why on  Earth would anything disconnect the rotor from gearbox?)

You reset your chop circuit by pressing Chop again.

In the sim, chop has at this time pretty low priority, that's why it doesn't do anything for those who try it. They have much more important features to get to life before chop...

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23 minutes ago, Razor18 said:

...In the sim, chop has at this time pretty low priority, that's why it doesn't do anything for those who try it. They have much more important features to get to life before chop...

Thanks for clarifying. Would be nice if ED indicated in their manual that this control has no function, resp. will be implemented later.

LeCuvier

Windows 10 Pro 64Bit | i7-4790 CPU |16 GB RAM|SSD System Disk|SSD Gaming Disk| MSI GTX-1080 Gaming 8 GB| Acer XB270HU | TM Warthog HOTAS | VKB Gladiator Pro | MongoosT-50 | MFG Crosswind Pedals | TrackIR 5

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True, they did not indicate  specifically chop for Apache bwing non functional yet, but they always mention before and after releasing the Early Access, that features will be appearing rather in order of "importance", not individual wishlists. And I guess the majority would not vote for functional chop button being the next most important thing now for the Apache. Just my 2 cent...


Edited by Razor18
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In a helcopter what is the primary situation requiring reduction in power from the engines to the rotor system? To counteract a spin caused by a tail rotor malfunction. 

Summarizing, I think it's chapter 9 of the -10,  "Tail Rotor Fixed Pitch Malfunction - In-Ground Effect"

"A fixed pitch failure may be evidenced by slow, intermittent, or no response to pedal input or no pedal movement. A left or right yaw may be apparent."

"If a failure occurs during in ground- effect hover, reaction may vary from adjusting collective and POWER levers during a left rotation to activating the CHOP button to stop a right rotation. In any case, the primary concern should be to land the aircraft with as little yaw rate as possible."

"If the aircraft has an uncontrolled turn to the right, reduce collective to begin descent. At approximately 5 to 10 ft AGL, perform a hovering autorotation by CHOP button - Press or POWER levers - OFF"

Power levers-OFF is generally not going to be an option, because where are your hands and what are they doing? No time to tell the front seater to pull the PCL's off. Thus the CHOP on the collective, where your hand is.


Hoot-U.S. Army Aviation, Retired

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