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Old 06-16-2018, 01:27 AM   #41
Chic
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Thank you
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Old 04-14-2019, 04:10 PM   #42
PilotMi8
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it turned out that it was necessary to fix not only the engine, but also the Main Rotor dynamics. Therefore, the process has gone quite deep. We apologize for the wait, but we have to redo engine+Main Rotor performance thoroughly, otherwise we need crutches in modeling, which we really don't like.
Besides, who is able to answer the questions that we still have about the engine, we will be grateful for the help (see the attachment).
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File Type: doc Engine_Limitations_questions_EN.doc (45.5 KB, 221 views)
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Old 04-14-2019, 09:48 PM   #43
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Quote:
Originally Posted by PilotMi8 View Post
... who is able to answer the questions that we still have about the engine, we will be grateful for the help (see the attachment).
Unfortunately, the document was difficult to open, so I'll re-post your questions

Quote:
Questions about the possibility of exceeding the limitations on the engine T53-L-13B

We’ve completely remade T53-L-13B engine model. New model is more accurate with precise characteristics according to documents and closer to the real deal. But in the documents we have, it is said that automatic control system has limiter of the max temperature which is not allowing EGT to go higher than 625°! under any conditions. So, it turns out that we cannot go outside of limits. But according to the real pilot's comments on forums it is not true. That is why we want to understand these things:

1) Is it possible for a pilot to exceed EGT 625°! and GasProducer of 101,5% by interacting with any helicopter or engine controls:
in AUTO mode
in EMERGENCY mode
during engine Accelerations check (Ground Idle to Maximum) what should be done for exceeding limits?

2) If exceeding those limits is possible please tell us about some examples from your or your colleagues experience with details about:
conditions within such exceeding happened: outside air temperature, altitude, takeoff weight;
what was done by pilot with stick, collective, AUTO-EMERGENCY switch or other controls
what were the avionics readings: N1, N2, MainRotor, Torque, EGT ?

3) During Autorotation descending: what were the avionics readings (N1, N2, EGT), if Main Rotor rev. is 320-330 (for example – altitude about 3000ft, FAT (OAT)=+15 at Sea Level) ?

If there are documents in which such engine characteristics are described or work of automatic control system explained, we would be very interested in getting such documents.

Thank you for any help!
Alexander Podvoyskiy, BST, Director

Last edited by Ramsay; 04-14-2019 at 10:13 PM.
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Old 04-15-2019, 05:36 AM   #44
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Maybe you should post the questions in a new thread in the main uh-1 forum to get more attention.
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Old 04-15-2019, 05:57 AM   #45
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Have a family friend who owns a Huey, so have fired across the questions to see if he can help.
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Old 04-15-2019, 06:02 AM   #46
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We have a current Huey operator in our group. I'll see if he can respond.

Thank you very much for taking the time to make this correct!
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Old 04-15-2019, 10:05 PM   #47
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Quote:
Originally Posted by PilotMi8 View Post
it turned out that it was necessary to fix not only the engine, but also the Main Rotor dynamics. Therefore, the process has gone quite deep. We apologize for the wait, but we have to redo engine+Main Rotor performance thoroughly, otherwise we need crutches in modeling, which we really don't like.
Besides, who is able to answer the questions that we still have about the engine, we will be grateful for the help (see the attachment).
I'm a Huey pilot

You are going really deep! I'll try to answer your questions. Let's see.

1) It's possible to exceed those limitations, but in some extraordinary situations.

Exhaust Gas Overtemperature Limits

During starts or accelerations, the following EGT limits must not be exceeded.

a. 625 to 676 C limited duration, 10 seconds
b. 676 to 760 C limited duration, 5 seconds
c. 760 C maximum EGT, do not exceed

You need to have something wrong in your helicopter for these things to happen. Bad FCU, bad compressor. If the above mentioned conditions are met, you need to shut down the aircraft right away in order not to damage the engine.

Gov: i have seen some confusion about this. What GOV does is keep constant rotor RPM at any collective imput. If you lower collective, less fuel is required to keep rotor RPM constant with less angle of attack (less wind resistance). If you raise it, more fuel is needed, so insted of managing the throttle, the FCU does it for you. If you have an axis asigned to your HOTAS or flight controls, you can try this manually for fun. It just isn't.

In some cases, the FCU can fail, for many reasons, so you have the chance of shutting down the RPM GOV and set them manually with the throttle. To do this, you must first go to idle and then turn GOV to emergency. Full open throttle in emergency gov will burn the engine. Unless you have an FCU failure, there's no reason on earth for you to fly without GOV engaged.

2) Any exceeded limitations usually take place in high density altitude enviroments and when maximun available torque condition is met. There's some aerodynamics going on that won't let you brake the aircraft mechanically. You will loose rotor RPM and fall before overtorquing for example. Depending on OAT, aircraft weight, temperature, you will have a maximum available torque that when reached will result in loss of power due to engine stall.

What is MAT? Is the maximum available power for the aircraft in specific conditions. This power is read, in the huey, in the Torque gauge. In high altitude density, after going through the performance charts you may come up with a MAT of 45. This means that when you reach 45, you will have reached 101,5% N1 and have a complete loss of power due to the compressor not being able to provide enough air to that power requirement. In different conditions, you may get that 101,5%N1 with a different TQ value.

In this condition of compressor stall you will see a drop in N2/NR with the aircraft going down, TQ is going down also because of power loss, and you will see an increase in N1 (101,5%) and an increase in EGT (because combustion is taking place without enough air)

https://www.youtube.com/watch?v=j7FbGtJYak8

The blackhawk starts falling and then the pilot, quickly, released the cargo before hitting it. Nice reaction.

In ISA conditions, with light aircraft, you may not have a MAT, and you would be able to reach the mechanical torque, (usually between 50 and 54, depending on engine calibration), which basically means breaking the aircraft mechanically. In this case, because of air conditions, the compressor is able to provide air to reach a power requirement that can damage the aircraft.

3) Autos: I never had an engine out, so all my autos were in a training environment. Closed throttle, all engine instruments (N1, TQ, and EGT) should go to idle values to that air conditions. N2 train is driven by the rotor, so they don't fall completely to idle (4200+/-), but usually stay between 4800 and 5200. THERE'S A CLEAR NEEDLE SEPARATION.

In an engine out i suppose that engine instruments will go to 0. No way for me to know what would happen to N2 in that case.

This is a good source, the maintenance test flight manual. I have one newer (2007) but it's in spanish

https://www.liberatedmanuals.com/TM-55-1520-242-MTF.pdf

PERSONAL OBSERVATIONS OF THE MODULE

I thing the module is pretty good, it gives a really good sensation of flying the Huey. BUT, there are a couple of strange things going on

1) Rotor behaves weird, with a tendency to overspeed really easy, specially when not loaded (no power applied).

2) Engine: all engine parameters are really sensitive and jump up or down when playing with the collective. Example: you are about to start an approach (35 TQ) and you lower collective (intended 25). All engine instruments will go all the way down (10TQ), you will start falling 1500ft/min and then they will go up (25TQ) without raising collective.

Same thing applies the other way. You apply collective, it will jump to a waaaaay higher value and then back to the one it should.

3) Feels TOO maneuverable with speed. Below ETL and in GE feels GREAT.

Hope it helps, let me know if you need more information!

ECV56_Largo
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Old 04-16-2019, 12:55 AM   #48
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Quote:
Originally Posted by patogn20 View Post
I'm a Huey pilot

You are going really deep! I'll try to answer your questions. Let's see.

1) It's possible to exceed those limitations, but in some extraordinary situations.

Exhaust Gas Overtemperature Limits

During starts or accelerations, the following EGT limits must not be exceeded.

a. 625 to 676 C limited duration, 10 seconds
b. 676 to 760 C limited duration, 5 seconds
c. 760 C maximum EGT, do not exceed

You need to have something wrong in your helicopter for these things to happen. Bad FCU, bad compressor. If the above mentioned conditions are met, you need to shut down the aircraft right away in order not to damage the engine.

Gov: i have seen some confusion about this. What GOV does is keep constant rotor RPM at any collective imput. If you lower collective, less fuel is required to keep rotor RPM constant with less angle of attack (less wind resistance). If you raise it, more fuel is needed, so insted of managing the throttle, the FCU does it for you. If you have an axis asigned to your HOTAS or flight controls, you can try this manually for fun. It just isn't.

In some cases, the FCU can fail, for many reasons, so you have the chance of shutting down the RPM GOV and set them manually with the throttle. To do this, you must first go to idle and then turn GOV to emergency. Full open throttle in emergency gov will burn the engine. Unless you have an FCU failure, there's no reason on earth for you to fly without GOV engaged.

2) Any exceeded limitations usually take place in high density altitude enviroments and when maximun available torque condition is met. There's some aerodynamics going on that won't let you brake the aircraft mechanically. You will loose rotor RPM and fall before overtorquing for example. Depending on OAT, aircraft weight, temperature, you will have a maximum available torque that when reached will result in loss of power due to engine stall.

What is MAT? Is the maximum available power for the aircraft in specific conditions. This power is read, in the huey, in the Torque gauge. In high altitude density, after going through the performance charts you may come up with a MAT of 45. This means that when you reach 45, you will have reached 101,5% N1 and have a complete loss of power due to the compressor not being able to provide enough air to that power requirement. In different conditions, you may get that 101,5%N1 with a different TQ value.

In this condition of compressor stall you will see a drop in N2/NR with the aircraft going down, TQ is going down also because of power loss, and you will see an increase in N1 (101,5%) and an increase in EGT (because combustion is taking place without enough air)

https://www.youtube.com/watch?v=j7FbGtJYak8

The blackhawk starts falling and then the pilot, quickly, released the cargo before hitting it. Nice reaction.

In ISA conditions, with light aircraft, you may not have a MAT, and you would be able to reach the mechanical torque, (usually between 50 and 54, depending on engine calibration), which basically means breaking the aircraft mechanically. In this case, because of air conditions, the compressor is able to provide air to reach a power requirement that can damage the aircraft.

3) Autos: I never had an engine out, so all my autos were in a training environment. Closed throttle, all engine instruments (N1, TQ, and EGT) should go to idle values to that air conditions. N2 train is driven by the rotor, so they don't fall completely to idle (4200+/-), but usually stay between 4800 and 5200. THERE'S A CLEAR NEEDLE SEPARATION.

In an engine out i suppose that engine instruments will go to 0. No way for me to know what would happen to N2 in that case.

This is a good source, the maintenance test flight manual. I have one newer (2007) but it's in spanish

https://www.liberatedmanuals.com/TM-55-1520-242-MTF.pdf

PERSONAL OBSERVATIONS OF THE MODULE

I thing the module is pretty good, it gives a really good sensation of flying the Huey. BUT, there are a couple of strange things going on

1) Rotor behaves weird, with a tendency to overspeed really easy, specially when not loaded (no power applied).

2) Engine: all engine parameters are really sensitive and jump up or down when playing with the collective. Example: you are about to start an approach (35 TQ) and you lower collective (intended 25). All engine instruments will go all the way down (10TQ), you will start falling 1500ft/min and then they will go up (25TQ) without raising collective.

Same thing applies the other way. You apply collective, it will jump to a waaaaay higher value and then back to the one it should.

3) Feels TOO maneuverable with speed. Below ETL and in GE feels GREAT.

Hope it helps, let me know if you need more information!

ECV56_Largo
I think there's been some confusion in Alex questions. I believe he and all the BST team understand all of what you explained very well since otherwise they could have never developed a module like the Huey. What they are asking is IF or not there is a system that prevents going past the limits as one or more of their available documents state.

The answer is not, but its hard to go past them as Largo explained, although you could do so depending on engine load and environment.


MAT is achieved by reaching the first of three limits in this order:

1- Torque
2- EGT
3- N1

The result is looking at what torque reading you get when reaching one of those limits. Of course if you reach the torque one, your limit will be that

Largo, nice explanation by the way, I flew the huey in Uruguay some time back.

Last edited by Hornetmadd; 04-16-2019 at 03:39 AM.
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Old 04-16-2019, 03:00 AM   #49
Chic
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Quote:
Originally Posted by patogn20 View Post
I'm a Huey pilot

You are going really deep! I'll try to answer your questions. Let's see.

1) It's possible to exceed those limitations, but in some extraordinary situations.

Exhaust Gas Overtemperature Limits

During starts or accelerations, the following EGT limits must not be exceeded.

a. 625 to 676 C limited duration, 10 seconds
b. 676 to 760 C limited duration, 5 seconds
c. 760 C maximum EGT, do not exceed

You need to have something wrong in your helicopter for these things to happen. Bad FCU, bad compressor. If the above mentioned conditions are met, you need to shut down the aircraft right away in order not to damage the engine.

Gov: i have seen some confusion about this. What GOV does is keep constant rotor RPM at any collective imput. If you lower collective, less fuel is required to keep rotor RPM constant with less angle of attack (less wind resistance). If you raise it, more fuel is needed, so insted of managing the throttle, the FCU does it for you. If you have an axis asigned to your HOTAS or flight controls, you can try this manually for fun. It just isn't.

In some cases, the FCU can fail, for many reasons, so you have the chance of shutting down the RPM GOV and set them manually with the throttle. To do this, you must first go to idle and then turn GOV to emergency. Full open throttle in emergency gov will burn the engine. Unless you have an FCU failure, there's no reason on earth for you to fly without GOV engaged.

2) Any exceeded limitations usually take place in high density altitude enviroments and when maximun available torque condition is met. There's some aerodynamics going on that won't let you brake the aircraft mechanically. You will loose rotor RPM and fall before overtorquing for example. Depending on OAT, aircraft weight, temperature, you will have a maximum available torque that when reached will result in loss of power due to engine stall.

What is MAT? Is the maximum available power for the aircraft in specific conditions. This power is read, in the huey, in the Torque gauge. In high altitude density, after going through the performance charts you may come up with a MAT of 45. This means that when you reach 45, you will have reached 101,5% N1 and have a complete loss of power due to the compressor not being able to provide enough air to that power requirement. In different conditions, you may get that 101,5%N1 with a different TQ value.

In this condition of compressor stall you will see a drop in N2/NR with the aircraft going down, TQ is going down also because of power loss, and you will see an increase in N1 (101,5%) and an increase in EGT (because combustion is taking place without enough air)

https://www.youtube.com/watch?v=j7FbGtJYak8

The blackhawk starts falling and then the pilot, quickly, released the cargo before hitting it. Nice reaction.

In ISA conditions, with light aircraft, you may not have a MAT, and you would be able to reach the mechanical torque, (usually between 50 and 54, depending on engine calibration), which basically means breaking the aircraft mechanically. In this case, because of air conditions, the compressor is able to provide air to reach a power requirement that can damage the aircraft.

3) Autos: I never had an engine out, so all my autos were in a training environment. Closed throttle, all engine instruments (N1, TQ, and EGT) should go to idle values to that air conditions. N2 train is driven by the rotor, so they don't fall completely to idle (4200+/-), but usually stay between 4800 and 5200. THERE'S A CLEAR NEEDLE SEPARATION.

In an engine out i suppose that engine instruments will go to 0. No way for me to know what would happen to N2 in that case.

This is a good source, the maintenance test flight manual. I have one newer (2007) but it's in spanish

https://www.liberatedmanuals.com/TM-55-1520-242-MTF.pdf

PERSONAL OBSERVATIONS OF THE MODULE

I thing the module is pretty good, it gives a really good sensation of flying the Huey. BUT, there are a couple of strange things going on

1) Rotor behaves weird, with a tendency to overspeed really easy, specially when not loaded (no power applied).

2) Engine: all engine parameters are really sensitive and jump up or down when playing with the collective. Example: you are about to start an approach (35 TQ) and you lower collective (intended 25). All engine instruments will go all the way down (10TQ), you will start falling 1500ft/min and then they will go up (25TQ) without raising collective.

Same thing applies the other way. You apply collective, it will jump to a waaaaay higher value and then back to the one it should.

3) Feels TOO maneuverable with speed. Below ETL and in GE feels GREAT.

Hope it helps, let me know if you need more information!

ECV56_Largo

Thanks for the insights
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A Co, 229th AHB, 1st Cav Div

ASUS Prime Z370-A MB, Intel Core i7 8700K 4.9GHz OC'd, GeForce GTX 1080 Ti 11GB OC'd, 32GB DDR4, 1TB SSD, Windows 10 (64-bit)
Samsung 65" 4K Curved Display (Oculus Rift occaisionally), Track IR5, VoiceAttack, Baur's BRD-N Cyclic base/Virpil T-50CM Grip, UH-1h Collective by Microhelis &
OE-XAM Pedals. JetSeat & SimShaker for Aviators.
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Old 04-16-2019, 09:50 AM   #50
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Thanks to everyone’s input in trying to improve the module, I’m looking forward to seeing the results of your work and dedication.
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