Huey Hover Power Check IGE

[Charly_Owl]

I did some tests to see if I understood engine performance charts properly... and I've come to a point where I don't know if I'm doing something wrong or if the in-game engine performance is somewhat "off".

 

For instance, I took a Huey loaded at 9000 lbs, spawned at Lochini (1500 FT pressure altitude and 20 deg C FAT) and did a hover power check.

 

I could maintain a 8 ft hover at more than 41-42 psi torque.

 

If I look at the torque I should need to perform this hover at this configuration (as shown in this picture) I shouldn't need more than 35 psi of torque for a 6600 /324 engine/rotor RPM.

 

 

Is there something I'm not doing correctly? This seems kind of weird...

Edited May 24, 2015 by Charly_Owl

[NoJoe]

Looks about right for a skid height of 8. I think you circled a skid height of 2 in the diagram. Unless I'm also misunderstanding something? (entirely possible)

[iFoxRomeo]

... and I've come to a point where I don't know if I'm doing something wrong or if the in-game engine performance is somewhat "off".

 

Both.

 

But regarding the chart:

Are the 20°C from the mission editor setting, or indicated by the FAT gauge?

Your step 4 is wrong. You have 8ft on the radar alt, but you go only to the 2ft line. So either you hover in 2ft and check torque or go to the 10ft line in the table.

 

 

Fox

[Charly_Owl]

Both.

 

But regarding the chart:

Are the 20°C from the mission editor setting, or indicated by the FAT gauge?

Your step 4 is wrong. You have 8ft on the radar alt, but you go only to the 2ft line. So either you hover in 2ft and check torque or go to the 10ft line in the table.

 

 

Fox

 

I had the same torque at 2 ft above ground. 20 deg is what I read on the FAT gauge.

 

Edited May 24, 2015 by Charly_Owl

[Charly_Owl]

Could it have something to do with the "Engine Resource" setting in the mission editor? I have no idea what that does...

 

 

Edit: I tested with 90 % and 100 % engine resource, hover torque at 2 ft is 41 instead of 42. It makes sense, but it's still close to 15 % off.

Edited May 24, 2015 by Charly_Owl

[GunfighterSIX]

Vover power check should be done at 5 feet, not 2. the "Engine Resource" setting tab really effects your max power available not your hover trq. But after going through the charts and writing out a few performance planing cards for the Huey I found it is about 2 psi off or 400lbs.

[Charly_Owl]

Vover power check should be done at 5 feet, not 2. the "Engine Resource" setting tab really effects your max power available not your hover trq. But after going through the charts and writing out a few performance planing cards for the Huey I found it is about 2 psi off or 400lbs.

 

That makes much more sense... 2 ft seems like a random value to perform an IGE hover check from. I'll probably just add a fudge factor of +2 or +3 psi just to be sure.

[iFoxRomeo]

I had the same torque at 2 ft above ground. 20 deg is what I read on the FAT gauge.

...

Well, then the simulation is off, if there is no difference between 2, 5, 10, 15, 25 and 50ft

I didn´t check that yet.

Could it have something to do with the "Engine Resource" setting in the mission editor? I have no idea what that does...

 

...

 

Edit: I tested with 90 % and 100 % engine resource, hover torque at 2 ft is 41 instead of 42. It makes sense, but it's still close to 15 % off.

No, it doesn´t make sense if the required hover torque value changes in this case. The helicopter needs a certain power value to stay in a hover(constant r-rpm), so it doesn´t care if the engine produces more or less maximum power.

 

I don´t understand why there is such a thing as "engine resource" in the first place.

 

Vover power check should be done at 5 feet, not 2. the "Engine Resource" setting tab really effects your max power available not your hover trq. But after going through the charts and writing out a few performance planing cards for the Huey I found it is about 2 psi off or 400lbs.

That´s you opinion. Or say its the operators´s choice. But Bell obviously provides values for 2ft, 5ft, 10ft etc...

So each of these heights are acceptable power check heights.

 

That makes much more sense... 2 ft seems like a random value to perform an IGE hover check from. I'll probably just add a fudge factor of +2 or +3 psi just to be sure.

See above.

 

 

You are using the metal blade chart(section 7) Charly. I thought the BST Huey has composite blades, but I can´t find a source that states we have CBs. Nevertheless, you are using an old version of this chart. The temperature at which you use the correction value is 0°C and lower, not 20°C.

 

Was the wind set in your testing environment?

 

 

 

Fox

[Charly_Owl]

Sorry for the delay, Romeo. I really had to go to sleep... writing can be exhausting at times.

 

You are using the metal blade chart(section 7) Charly. I thought the BST Huey has composite blades, but I can´t find a source that states we have CBs. Nevertheless, you are using an old version of this chart. The temperature at which you use the correction value is 0°C and lower, not 20°C.

 

Was the wind set in your testing environment?

 

Fox

 

I used the charts in the -10 manual for the UH-1H/V (15 feb 1998), the TM 55-1520-210-10.

 

No wind was set.

 

What manual did you use to get these composite blade charts?

 

The torque value I get form a 10 ft hover fits what I have (42 psi), bang on. But I have a 42 psi torque for a 2 ft and 5 ft hover. I can't explain why the torque doesn't seem to change since the charts seem to state otherwise.

Edited May 24, 2015 by Charly_Owl

[iFoxRomeo]

Sorry for the delay, Romeo. I really had to go to sleep... writing can be exhausting at times.

No sweat Charly.

I used the charts in the -10 manual for the UH-1H/V (15 feb 1998, the TM 55-1520-210-10.

I guess you mean 15 feb 1988

 

I use the -10 released 15 feb 1988 with changes up to C19 from 31 dec 2002

 

No wind was set.

 

What manual did you use to get these composite blade charts?

The snippet I posted is not for the composite blades. It is for the metal blades.

There is no correction value for composite blades.

You can distinguish charts for metal blades from charts for composite blades by the chapter.

 

Chapter 7 Performance with metal blades

Chapter 7.1 Performance with composite blades

 

I thought the BST Huey has composite blades, but I can´t find evidence for this claim. It was mentioned in several discussions, but I can´t find a source confirming this. So I will use the metal blade performance charts till I find evidence for composite blades.

Actually the visual appearance of the rotorblades ingame is the shape of the metal blades.

 

The torque value I get form a 10 ft hover fits what I have (42 psi), bang on. But I have a 42 psi torque for a 2 ft and 5 ft hover. I can't explain why the torque doesn't seem to change since the charts seem to state otherwise.

One explanation could be that you were so tired that you were playing with the collective, so that the torque indicator didn´t come to the lower values..... But I don´t think that this is what caused the wrong values.

There are other indications that some parameters are off. This is an additional one. I really hope for improvements is DCSW2.0

 

You can grab the -10 from user Griffin here

 

Fox

[Charly_Owl]

I guess you mean 15 feb 1988

 

Curse you, fat fingers. Yes, I obviously meant 1988.

 

One explanation could be that you were so tired that you were playing with the collective, so that the torque indicator didn´t come to the lower values..... But I don´t think that this is what caused the wrong values.

There are other indications that some parameters are off. This is an additional one. I really hope for improvements is DCSW2.0

 

You can grab the -10 from user Griffin here

 

Fox

 

Thanks for the link. I think I figured out why I was having some issues with torque: I had my curves wrongly set up for the collective. Since I modified it, I have a much smoother input that allows me better control on the torque.

[DaddySchlich]

How do you recommend setting the collective curves for the Huey? Thanks so much.

[Charly_Owl]

Depends what stick you got. If you have an extended stick, no curves are needed.

 

I have a standard warthog hotas and my collective is:

 

Deadzone 0

Saturation x 100

Saturation y 100

Curvature 11

[DaddySchlich]

I have a MS FFB2. For helicopters, it makes all the difference to me. I'm not aware of any FFB rudder pedals

[WildBillKelsoe]

there is a 1986 manual TM 55-1520-210-10 for UH-1H/V. I think this is the one BST used.

 

Our DCS manual clearly states composite blades not metal blades

 

Its on page 11 at the foot of the table

 

Note. The composite rotor blades provide a 6% improvement in the UH - 1H's hovering capability and a 5 to 8 percent reduction in fuel flow in forward flight.

[WildBillKelsoe]

I just checked your chart, and without applying calibration correction for 20°C, which is less than 0.4 by trend setting, the torque for hovering at 8 ft at calm winds and 9000 lbs GW is 40.5 PSI.

[WildBillKelsoe]

One more thing, you should subtract a foot and few inches from your radar altimeter as the skids are 1 ft 3.48 inches from the belly where the radar altimeter is.

[Jacks]

How can torque be measured in PSI, I assume this is measuring at some point along the turbine.

[WildBillKelsoe]

Torque is measured as lbs/ft(squared), but in the real huey, and for simplicity, it is measured in PSI. the torque is that imposed on the main rotor shaft. I hope I'm right.

[Xtrasensory]

http://www.askacfi.com/23366/how-does-the-torque-indication-system-measure-torque-in-the-helicopters-and-turbo-prop-aircrafts.htm

 

2nd responds might clear some answers.

Dependiing on engine and aircraft torque can be measured in different ways. Most likely the Uh1 measures an oil pressure somewhere aswell, thus explaining the use of PSI instead of lbs/ft.

Edited September 7, 2015 by Xtrasensory

[WildBillKelsoe]

Good find!

[WildBillKelsoe]

OK, I can attest that there is definitely something wrong with torque in the sim. Today I flew the quickstart weapons practice mission, only swapped gunners gatling for pig noise makers, so my weight at prep mission was 8909 lbs, of which 487 lbs of JP-4 fuel was loaded (35%). Ambient FAT was 22 degrees Celsius, winds blowing to 125 at 8 kts.

 

So after buzzing around, I came to 5 foot hover on FARP, with less than 100 lbs of fuel.

 

If I take that 7-3 chart hover power required, at 100 lbs of fuel, it should be 8522 lbs with weapons intact (not fired), under said FAT, without winds, at zero pressure altitude, it should be 35 PSI, however torque was well over 40 PSI, with weapons expended! While I don't know the physics or factors involved, logic says that a lighter chopper will demand less torque, facing wind (305 degrees). ED, or BST need to revise the model in this regard.

[iFoxRomeo]

there is a 1986 manual TM 55-1520-210-10 for UH-1H/V. I think this is the one BST used.

 

Our DCS manual clearly states composite blades not metal blades

 

Its on page 11 at the foot of the table

 

This Quote just says that composite blades provide benefits. Not that the DCS Huey is equipped with composite blades. The ingame visual shape of the DCS Huey´s blades ist the shape of the metal blades.

 

I just checked your chart, and without applying calibration correction for 20°C, which is less than 0.4 by trend setting, the torque for hovering at 8 ft at calm winds and 9000 lbs GW is 40.5 PSI.

 

No correction above 0°C. 20°C is a typo in the old flightmanual.

 

One more thing, you should subtract a foot and few inches from your radar altimeter as the skids are 1 ft 3.48 inches from the belly where the radar altimeter is.

 

No, don´t do that. What point of the skids would you take than? The skids have different heights themselves. The front part is higher than the back part of the skids. The left skid hangs lower than the right skid during hover. That really isn´t necessary.

 

How can torque be measured in PSI, I assume this is measuring at some point along the turbine.

 

Back then when the Huey was constucted, they had no idea how to measure the torque. Today you have percentage as "unit" for the torque. PSI is just an equivalent to the torque. Xtrasensory´s link points into the right direction. The Huey has a device that puts out a psi value corresponding to the power input of the engine to ...

 

Torque is measured as lbs/ft(squared), but in the real huey, and for simplicity, it is measured in PSI. the torque is that imposed on the main rotor shaft. I hope I'm right.

 

... the main gearbox. The main rotor or its shaft is not limiting here. It´s the MGB.

 

I guess you meant lbs/ft ->without squared<-

The SI Unit for torque is Nm

 

 

Unfortunately the charts in the real flight manual don´t fit into the DCS Huey. Engine poweroutput, torque and EGT of the DCS Huey do not correspond to the real one.

I´m hoping and waiting for DCSW 1.5 and 2.0. Perhaps the Huey gets an update then. I really hope so.

 

Fox

[plhought]

...Back then when the Huey was constucted, they had no idea how to measure the torque. Today you have percentage as "unit" for the torque. PSI is just an equivalent to the torque...

 

This is pretty misleading - of course they knew how to measure the torque. I'd say 90 percent of gas turbine engine installation in either turboshaft/turboprop installations with less that 1500hp use oil pressure (PSI) as a measurement of torque. It may not say that on the gauge, but that's what it's actually measuring.

 

In the T53 specifically -

The torquemeter is a hydromechanical torque measuring device used to measure the torque applied to the power output shaft in oil pressure (PSI) The torquemeter consists of two plates separated by steel balls in conical (inclined) sockets and a spring loaded oil control poppet valve which controls oil pressure in the cavity. The resistance to rotation of the reduction gears due to load on the power shaft causes the moveable plate to rotate slightly. This movement displaces the balls in their sockets which forces the moveable plate aft, opening the poppet valve. High pressure oil from the torquemeter oil pump enters the cylinder cavity which equalizes torque forces and stop the plate from moving. The amount of oil pressure required to stop the plate is directly proportional to the torque on the power shaft and is indicated in psi on the torquemeter gauge in the cockpit.

 

What unit of measure is irrelevant. You could simply re-mark the gauge backing with percentage, units of unicorn farts, or whatever. For simplicity in ensuring calibration and maintenance, it's typical to retain the actual unit of what the device is measuring. In the torquemeter's case, it's oil pressure.

 

PT6's use a similar system, with a floating outer carrier ring that's helical cut. As torque is applied to the reduction gear assys, the outer ring is displaced for & aft, and oil pressure at the torquemeter is reflected in how much the ring has been displaced - allowing the measurement of torque.

Edited September 28, 2015 by plhought

[msalama]

Could someone with the know-how run some new tests now that v1.5 is here to see if anything has changed, please? I'd do it myself, but I'm a complete bozo as it comes to this kind of activity, so my results would probably be less than worthless. Thanks!