Chopper R.P.M Control

[_RAAF_Smouch]

I'm just wondering how many people who predominatley fly the choppers once airborne actually lower/raise the r.p.m settings for engine temp control?

And does this also help in landing the birds?

Cheers

~S~

[Aginor]

IIRC overheating effects are not modelled in the Huey yet, not sure about the Mi-8. The Ka-50 does ist automatically anyway.

So actually, I don't mind the rpm at all. Yet.

 

As for the landings: I can't imagine why a lower rpm should be an advantage, can anybody explain that to me?

[Robin_Hood]

I'm just wondering how many people who predominatley fly the choppers once airborne actually lower/raise the r.p.m settings for engine temp control?

 

And does this also help in landing the birds?

 

Cheers

~S~

 

I'm pretty sure every chopper currently modeled has an automatic regulation of the RPM, so I'm not sure a manual meddling would help ?

[Yurgon]

I'm pretty sure every chopper currently modeled has an automatic regulation of the RPM, so I'm not sure a manual meddling would help ?

 

I agree. There are ways to influence RPM, but under normal circumstances the throttle/governor will be in the "Auto" position.

 

The only way to influence EGT therefore is to keep the collective at a low enough setting.

 

The single engine Huey for instance is rather under-powered. With lots of fuel, cargo and/or external weapons, it probably can't be hovered within the engine limits for continuous operation. It may even be necessary to put it way into the red area of the EXH TEMP gauge just to take off and get ETL.

 

In forward flight it shouldn't be too difficult to keep EGT within limits, but this will in turn limit torque and therefore speed. As a rule of thumb, 80 to 90 knots are usually achievable with EGT at or below 610°. In my experience, going any faster usually means EGT above 610° and should be limited to 30 minutes max as per the manual.

 

AFAIK and as said before, engine overheat isn't currently modeled in the UH-1H and Ka-50 modules. Not sure about Mi-8, although I would be mildly surprised if it was actually possible to overheat the Hip's engines. But I like to treat my choppers as if engine overheat was already modeled so that I don't end up falling from the skies once the feature gets implemented. :music_whistling: :D

 

Edit:

 

And does this also help in landing the birds?

 

I don't see how lowering the RPM would help landings. I don't know if hot engines suffer from loss of power (before they catch fire and melt, obviously :D), maybe the resident experts can chime in on that. Not sure what you're getting at, maybe you could rephrase the question so that we get a better understanding of what you're referring to?

Edited October 25, 2014 by Yurgon

[effte]

You can, and are supposed to, trim the RPM governor. Yes, it will maintain RPM automagically, but the RPM it shoots for can be nudged up and down.

 

It's in the checklist to make sure you're getting the full RPM. Lower RPM means less power at a given torque setting. Not really to do with temp control at all.

 

And apart from making sure you have all the nominal power available before overtorqueing, it doesn't help with landings.

[tusler]

I have found if I need to dive great distances in the KA50 By lowering the rotor rpm I can fly at substantially faster speed loosing thousands of feet very quickly without ripping the rotors off.

[Aginor]

What do you mean with "substantially faster"? More than 320kph?

[Irregular programming]

I have found if I need to dive great distances in the KA50 By lowering the rotor rpm I can fly at substantially faster speed loosing thousands of feet very quickly without ripping the rotors off.

 

This is a "bug" in the flight model, doing this doesn't cause any stress to the air frame at all.

[Yurgon]

What do you mean with "substantially faster"? More than 320kph?

 

In the Ka-50? Try 400+ :D

 

(That is including recovering from the dive; the generators will usually cut out, but that's about it if you're very gentle on the controls as you get back to level flight; probably need to check F2 view for speed because in the cockpit it won't show correctly :))

 

Edit:

 

I just re-read tusler's statement. In my experience, this has nothing to do with RPM and everything with the collective all the way down to the floor; maybe that's what you meant, not sure.

Edited October 26, 2014 by Yurgon

[DieHard]

I have found if I need to dive great distances in the KA50 By lowering the rotor rpm I can fly at substantially faster speed loosing thousands of feet very quickly without ripping the rotors off.

 

Yeah, me too. In the Ka-50, I have my CH Products Pro Throttle which I use for my collective control, mapped to two buttons. Drop like a rock I engage and hold the button the "Free Turbine RPM to Low" while lowering the collective down. When I get down to where I want, I allow some altitude so the rotors have distance before I could hit the ground to speed back up and engage "Free Turbine RPM Nominal" while raising the collective up and adjust collective as is necessary. I do not cruise very high up, but I do fly treetop level in the mountains along ridges and descend into valleys very quickly down into ravines usually evading an airborne threat if I survived the missile. I am using the AP Director in manual control.

 

I only change my throttle's speed off the usual cruise setting to add more power for an emergency power boost up over a hill; or if battle damaged losing an engine. If damaged losing an engine I also flip the engines' governors off and turn the APU on and the crossfeed valve on.

 

Temperature for me is not a factor to consider in the top of thread situation.

 

I have never had an engine overheating issue I can remember.

Edited October 27, 2014 by DieHard

[Yurgon]

In the Ka-50? Try 400+ :D

 

QED :)

[Fri13]

In the Ka-50? Try 400+ :D

 

(That is including recovering from the dive; the generators will usually cut out, but that's about it if you're very gentle on the controls as you get back to level flight; probably need to check F2 view for speed because in the cockpit it won't show correctly :))

 

Edit:

 

I just re-read tusler's statement. In my experience, this has nothing to do with RPM and everything with the collective all the way down to the floor; maybe that's what you meant, not sure.

With KA-50 it is better to get a habit to lower collective every time hard maneuvers are required. Then learn how much collective is required to pull a needed turn.

 

KA-50 allows all kind crazy maneuvers when collective is down.

 

Like full nose/rotors a down altitude droppings from 400-500m to few meters. The problem is just to learn the autorotation and then required glide altitude for given weight, that is around 30-40m usually on me, so you get safely to ground effect altitude if needed.

 

For friend sake who was "first time" in KA-50 as wingman, we enabled the Game Flight modeling and I can't stand it well as I can't maneuver KA-50 as learned. And trying quickly to get altitude off, even from 30m to 4-5m range is most often result of death.

 

The 400+ km/h sounds about right and there is huge benefit to have a effective tail and co-axial rotors.

[Yurgon]

KA-50 allows all kind crazy maneuvers when collective is down.

 

Agreed. :)

 

For friend sake who was "first time" in KA-50 as wingman, we enabled the Game Flight modeling and I can't stand it well as I can't maneuver KA-50 as learned.

 

Yeah, I once took control in a track with Game Flight Mode. It's terrible. You can't even fly loopings in Game Flight Mode. :D

[Buznee]

The more horsepower an engine produces the higher the turbine temperature. Therefore raising the rpm and setting the engine to the torque limit will be hotter than the lower rpm at the torque limit. Unfortunately most of the time on the current huey model you can't get to the torque limit without overtemping the engine. Fortunately enough engine damage due to overtemp is not modeled yet. Fry away!

[BitMaster]

With KA-50 it is better to get a habit to lower collective every time hard maneuvers are required. Then learn how much collective is required to pull a needed turn.

 

KA-50 allows all kind crazy maneuvers when collective is down....

 

 

When you look at the swashplate position at hover and it's max UP and DOWN travel end points ( Blade Pitch Angle for Cyclic & Collective ) it is obvious why you have to set collective somehow back to the standard hover position so you cyclic has enough travel to actually do something.

 

What many beginners, Sim or R/C do wrong, is when they try to get out of a steep dive nose down they pull collective far too early, before the nose is horizontal. If you try to get the nose 90° up while full collective you will soon find out there is very very little cyclic travel possible.

Keep collective around hover and your nose will do what your stick says, then gently apply collective to flatten out.

 

 

If you could look at a swash plate you could see what I mean in no time.

 

Bit

[Fri13]

When you look at the swashplate position at hover and it's max UP and DOWN travel end points ( Blade Pitch Angle for Cyclic & Collective ) it is obvious why you have to set collective somehow back to the standard hover position so you cyclic has enough travel to actually do something.

 

What many beginners, Sim or R/C do wrong, is when they try to get out of a steep dive nose down they pull collective far too early, before the nose is horizontal. If you try to get the nose 90° up while full collective you will soon find out there is very very little cyclic travel possible.

Keep collective around hover and your nose will do what your stick says, then gently apply collective to flatten out.

 

 

If you could look at a swash plate you could see what I mean in no time.

 

Bit

Not just pulling from dive, but the problem is that co-axial rotos blades clash to each other very easily in rough maneuvers if collective is up. That's why when doing loops and hard ACM to avoid missiles or fire, it is crucial to learn in what moves collective needs to be totally off, not even in hover level as otherwise you don't have blades anymore.

 

And when coming from deep dive, if there is speed, helicopter is flu as airplane, don't touch collective at all. Requirement to know when and how to do autorotation is very important as well because that way it is possible get quickly down without clashing blades or gaining air speed or momentum.

 

And as the problem is too that co-axial rotors are used to turn the helicopter, it is required to pull collective up to do maneuvers as without blades having higher angle of attack, you don't turn easily or at all, the swashplate has enough traveling anyways with a co-axial designs as there is a another rotor disk giving more counterforce for maneuvers. So simply learning the co-axial helicopter flight possibilities is easier when learning from keeping collective down when in hard maneuvers and you can do almost anything. And when speed is slow enough, loops etc can be done with full collective too with more powerful control reactions.

Edited October 28, 2014 by Fri13

[Aginor]

Wow, looks like there are quite some things about the KA-50 I don't know yet. :O

[DSPALLASVI]

Have tried to mimic EGT temps 'damage' in Huey model of DCS:

 

http://forums.eagle.ru/showthread.php?t=142452

[Snarf]

Gas turbine helicopters use pitch adjustments to vary thrust/lift not RPM, it is something you need to tweak on light reciprocating engined helicopters like the R22, but even then they try to fly on 100% RPM but the throttle geometry and correlation boxes don't compensate as well as the Governor and droop cam systems on Gas turbine helicopters.

 

In my experience the only time you really had to worry about temperature was during a start when an overtemp could happen. For normal operation with a servicable engine the RPM is held constant by the N1 and N2 governor and adjusted with increases in collective via the droop cam. The beep switch on the collective arm is only used on start to adjust the N2 RPM to the correct RPM.

 

More critical things when running were correct operation of the Variable Inlet Guide Vanes (VIGV)s and bleed bands either of which could cause serious damage if not working correctly.

 

Generally the Huey would overpitch before it overtemped, on a hot and humid day with a high loading this was more likely to happen.