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Manual Use of Governor for Overloaded Takeoff?


San Patricio
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So I'm a little confused on the proper technique for taking off with a heavily loaded bird from a FARP or other location where you can't get a rolling start. I've experimented with two methods:

 

1. As suggested during one of the UN campaign missions, I switch the governor to emergency. This shoots engine rpm far into the red but gives me enough power to do a vertical takeoff even with a heavily loaded craft. I then switch back to automatic once I have some altitude and airspeed. Basically this works, at least in the sim, but it feels like I'm cooking my engine. I tried reducing the throttle after switching the governor to emergency (which seems to be what the manual suggests), but this seems to lower RPMs way too drastically.

 

2. With the governor on automatic, I've tried cranking up the RPMs using the switch on the collective. This also seems to help a little.

 

Is either of these two methods the "right" way to do it? Is there something I'm missing? I've read the manual but it seems a bit vague on this point.

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Don't know. I've tried that way, but it seems dodgy. I've never read of real Huey pilots doing it, not even in Chickenhawk when they had to take off with gross overloads. The only thing I've ever heard of for coping with overloaded takeoffs is to do running takeoffs, even if that entailed dragging the skids in the dirt for long distances.

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In RL the VN chopper pilots used the Gov,running,bounce..even resorting to some crew members running along side of the AC during a running start (dragging skids) and jumping/diving in after a 1.5-3' lift was obtained..The bounce was the most common used.

 

I would have to say lowering the throttle after flipping the GOV would defeat the purpose all together.

 

http://www.dynamicflight.com/flight_maneuvers/running/

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In RL, messing with the GOV is forbidden. Basicaly if EGT was modeled you would see that you would melt the engine down by doing so, but it's not modelled yet. The only thing you can do in RL in such situations is running takeoff (if you have wheels), or hovering as close to the ground as you can, even 5cm and 'running' takeoff by using the in ground effect as much as you can

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That wouldn't help much... As soon as you start raising the collective and the heli becomes light at it's skids, not to mention that you will have to raise maximum collective the heli will no doupt spin if you have right pedal (just think that with max coll you need max left foot). Right pedal will get you nowhere imho...

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In Chickenhawk there was a piece about having to get over the perimeter wire. He released the energy with a change in direction and got an extra bit of lift to clear the obstruction. Its a while since I read it but thats how I recal it worked:)

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In Chickenhawk there was a piece about having to get over the perimeter wire. He released the energy with a change in direction and got an extra bit of lift to clear the obstruction. Its a while since I read it but thats how I recal it worked:)

 

Was he airborne or on the ground trying to take off when he did that?

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Was he airborne or on the ground trying to take off when he did that?

 

He was airborne but couldn't move far enough to enter ETL so he stood on the left pedal to get a tiny bit of extra lift and used it to punt himself over the fence.

 

:vietnam:

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Well that's a different story. He had the power (even marginal) to get airborne. If you don't even have the power to lift even some few cm from the ground right pedal can't help out of your situation imho... Few times have I found myself (in RL) in a situation that I must take off close to maximums. I always make sure that at least I can use the 2.5min red engine temp area during takeoff (not refering to UH-1). If that is not enough I call it off... There is one last 12sec red area but won't use it for takeoff. Only for emergencies while airborne...


Edited by sondo214
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FF to 13:00 min mark for statement and actually demo of the "bounce"

 

I do know that in the early 60's a single UH-1B loaded 36 people on a single mission and was able to evac the full load + crew will look for actual article and pics in US Army Aviation Digest to cite and post.

 

Also the first firefly mission flown by my good friend 3-3 w/ the 120 AHC Razor Backs he flew at treetop level 25-30 kts GOV off for the entire mission battling to maintain ETL and avoiding VRS.

 

Keep in mind that most chopper pilots in VN broke every rule in the book while flying.

 

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Edited by scrtagnt69
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FF to 13:00 min mark for statement and actually demo of the "bounce"

 

Thanks for that. Of course, the "demo" is not a bounce at all, no matter how many sound effects the TV show adds to make it seem so. And of course, there are no "springs" in the skids and there is also no "springiness" to the skids and they will absolutely not help you take off if over weight. I have no doubt that the pilot who made that statement fully believes that he bounced a Huey off the ground to get it into the air, but I can assure you that it just didn't happen, at least not in the way that he describes.

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I asked my buddy Steve "Tooth" Bookout what situations he had been in that warranted flipping the GOV off (beeped'er)

His reply...

 

Yes, I have beeped’er up to get out of a hole.....I graduated as a Warrant Officer 1 in May of 1969 from helicopter flight school and wound up in Viet Nam a month later. My first duty assignment as a helicopter pilot was with Charlie Company, 158th Aviation Battalion, 101st Airborne Division located in I Corps. My call sign was Phoenix 62. Charlie Co. flew ash & trash (passengers & misc. supplies), combat assaults, supported ARVNs and Special Forces/SOG teams. We also "jumped the fence" on a regular basis into Laos and once in a while, North Viet Nam.

 

My first mission came the next day after signing in at the orderly room. A Special Forces team was in very heavy running fire fight about nine miles into Laos. They had suffered dead and wounded and were running low on ammo. I was grabbed to fly co-pilot as everyone else was out flying. The unwritten law of Phoenix was: “If Americans were on the ground, Phoenix would get them out". Upon arrival, it looked like some photograph of the Argonne Forrest in WWI. The LZ was at the edge of a cliff. The LZ had trees knocked down, shattered into grotesque shapes, no leaves at all, and others standing with their tops blown off and limbs severely damaged. LaosSmoke was rising here and there. We were required to hover down thru the remains of those trees still standing in order to get the troops on board. This required us to swing the tail rotor one way or the other several times to avoid striking limbs and branches. Crikey, I was not prepared for what was occurring in such a short span of time….and this was only my second day with Phoenix!

 

NVA (North Vietnamese Army) were at the edge of the woods running towards us like demons and firing AK-47s. We had punctured the belly of the Huey with a stump without getting the skids on the ground and had to work ourselves off of it. The Green Berets were throwing their dead and wounded on board as quickly as possible, all the while returning fire at the advancing enemy. Even though all our weapons were working overtime, the PAVN (People’s Army of Viet Nam) kept coming. (I was no help because there were only six rounds for my .38.) We attempted to bring her up, but the ship was overloaded. Every unessential thing, helmets, packs, chicken plates, cans of oil, and etc. were tossed overboard trying to lighten her. The old girl was carrying six more passengers than what she was designed to carry, but ever so slowly we arose. I had beeped the engine up to MAX. RPM, but it started to decay as did rotor rpm about half way out of the hover hole. I was pulling the guts out of the turbine engine. Rounds had hit our bird in several places and the temperature gauges started to climb. Our main rotor blades chopped through branches and limbs and a pretty good vibration had set in before we climbed over the twenty foot tree stumps. After clearing the trees, we pedal turned, dropped our nose over the cliff and took a roller coaster ride down the mountain side rebuilding rpms and began our run towards the A Shau valley and home. Both of us pilots had sweat rings in our armpits, nerves were really frayed, engine and transmission temps still climbing, the rotor vibrations getting worse, and the smell of the dead were making the idea of getting back home seem remote. Somehow, we made it back to Camp Evans and shut down at the surg hospital. Upon inspecting our aircraft, we discovered about 2 feet of each main rotor blade had been sheared off in the trees. Our transmission had taken a hit and the engine had two bullet holes. While walking back to my hooch, I was thinking this had been one Hell of an initiation.

The company was kept very busy for the next several days. A thirty ship combat assault had just been completed one afternoon and my aircraft commander, who was also our instructor pilot, said "Mr. Bookout, you haven't had your standardization check ride and the local area orientation ride to show you the boundaries of our area of operations yet." He gave me an autorotation upon arrival at Evans and I greased her onto the runway. We were both laughing as we hovered over to the "nest", because the two rides were supposed to be the very first flights I took---well over two weeks earlier.

 

When we'd go to Quang Tri for a SOG mission (you can read about us in 'The Price Of Exit' by Tom Marshall, and CW2 by Layne Heath, both ex- Phoenix pilots) we'd be told that if we went down, we'd be listed as missing in action-presumed dead. No one was coming after us and we accepted it as it was our job. Sometimes we weren't allowed a map to get us to the drop off point and we'd have to rely on one of our pax (passenger) to guide us to the insertion point. We knew how to get home, though. Once we made the insertion, Marshal Dillon's sage advice to "get out of Dodge" was quickly followed.

 

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Edited by scrtagnt69
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I also asked Bookie about the bounce and flex of skid.

His reply:

 

I do not know about flex and other scientific stuff designed in, but we would sometimes be so overloaded that we would have to make a running take off with the CE & gunner running along side the bird to reduce weight. We could hover just a bit as we moved forward and would bounce several times before getting enough air speed to reach translational lift. The crew would jump aboard at the last moment and we would be airborne.

 

bookie_1_zps04d31b4b.jpg' alt='bookie_1_


Edited by scrtagnt69
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Thanks all for the interesting responses and stories. I actually found something on this in the Army UH-1H/V manual:

 

http://hoiquanphidung.com/tailieu/Bell-UH1H-Flight-Manual.Stamped.pdf

 

In section 8-33, it offers advice on heavily-loaded takeoffs. You can read for yourself, but in sum it does suggest that operators can increase "beep" on the governor with the GOV INCR switch in order to maintain rotor RPM during a heavily loaded takeoff. This is, to my understanding, something done with the GOV still set to auto and is not the same as the procedure suggested in the UN campaign missions (which involves flipping the GOV to emergency).

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  • 5 years later...
... The only thing you can do in RL in such situations is running takeoff (if you have wheels), ...

 

Don't need wheels to do a running takeoff. I've done running takeoff due to high DA. You just have to be very careful as to not wag the tail and remain as close to straight as possible. Could get messy if one of the skids catches. Very dangerous, especially if high DA is due to high ambient temps (soft tarmac).

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the point of the governor override is to allow the rotor RPM to increase beyond normal safe levels.

so the inevitable onset of rotor droop will occur later. as you have more energy stored in the rotor/engine system at faster RPM.

 

so with the collective down. release the governor switch and then watch the rotor RPM increase.

when it starts getting fast. thats when you lift and attempt takeoff.

because of the over speed. you may have enough time to lift before droop occurs.

the system wont destroy itself because the droop is inevitable. it will govern the system.

the only danger is over speeding before you pull collective.

 

you can also leave the governor on and use the increase Rotor RPM switch on the collective. to increase the RPM but you cannot go as high this way.

 

what is a safe over speed? a good philosophical question :)

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the point of the governor override is to allow the rotor RPM to increase beyond normal safe levels.

so the inevitable onset of rotor droop will occur later. as you have more energy stored in the rotor/engine system at faster RPM.

 

so with the collective down. release the governor switch and then watch the rotor RPM increase.

when it starts getting fast. thats when you lift and attempt takeoff.

because of the over speed. you may have enough time to lift before droop occurs.

the system wont destroy itself because the droop is inevitable. it will govern the system.

the only danger is over speeding before you pull collective.

 

you can also leave the governor on and use the increase Rotor RPM switch on the collective. to increase the RPM but you cannot go as high this way.

 

what is a safe over speed? a good philosophical question :)

 

Haha, what constitutes "a safe overspeed" is very clearly written down in the flight manuals. In my aircraft (Modified twin huey), thou shall not exceed 100% above 30% torque, and you can go as high as 104.5% if below 30 torque (autorotations, tac decels, etc.). Anything above these and the bird is broken and must be written up. Above 110% rotor, the entire powertrain gets a rebuild, and you get to join the "million dollar club."

 

Governor manual is not there to allow you to exceed 100%, it is there in case of a failure of the automatic fuel control unit. One of the emergencies we practice regularly in our simulator is a governor failure, where the AFCU fails to properly maintain RRPM (either too high or too low), and you must switch to manual governor. This means you maintain rotor RPM within the limits above by manually increasing or decreasing the throttle as you make collective changes.

 

The gov manual procedure in the campaign would destroy the aircraft, hands down. The engine would overtemp and the rotor would far exceed maximum RPM. There's also no real value to it, as the engine will give you all it's power in automatic mode anyway. I guess it would give you a very short lived boost on the initial pickup until the rotor decayed, but you'd have to use that to transition forward through TL or something otherwise you'd just end up going back down - and spinning the RRPM up that high would break the aircraft, as mentioned above.

 

The use of the Incr/Decr switch is something different, it is done in auto mode and just adjusts the rotor RPM that you want the governor to maintain. We always keep it at 100%, except for certain situations where we'll beep down to as low as it goes (97%) to keep rotor in check during dynamic manoeuvres or to save fuel on cross countries. We don't go above 100% because of the 30% torque rule, though it will go as high as 101.5% if you let it. I suppose if you were in a sticky spot, you could beep it up to get out, the damage would be minimal (and much less than a bullet I'm sure!), but it would provide very little benefit.


Edited by Sandman1330

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