P-38 Rpm

[Hajo]

I snapped a screenshot and sent off to a C130 aircraft commander who has been in Hercs for a good while for a more thorough explanation and confirm that what's been understood here is or isn't what actually happens.  Not sure what part of the world he's in at the moment.

What you don't believe what I was told by Air Force C-130 crew?  Kathy and Paul are good friends of mine.  Unusual that the wife is a Pilot and Paul flight engineer.

Btw Paul brought me back an American flag flown over their base in Iraq.  I've yet to pick it up........I'm lazy. I am trying to get in touch with them through operations

at the 910th at Youngstown Air Base.  Been so long I talked with Maintenance at the 910th and Paul is no longer there.  They may have retired, good for them.

Their Air Base: http://www.youngstown.afrc.af.mil/Home.aspx

[Golfer]

Didn't say I didn't believe you or your friends weren't anything other than wonderful.

I don't know em so I can't ask em.

[Golfer]

FWIW I believe you. I'm asking someone to learn how it works. I haven't any first hand experience with a Herc.

[Hajo]

FWIW I believe you. I'm asking someone to learn how it works. I haven't any first hand experience with a Herc.

It's marvelous aircraft.  I was interested in the hydraulics chiefly.  So Paul took me through the aircraft.  He said "this is the reservoir".  I couldn't believe it.  It was the size of a coffee can.

Sitting in the Pilots seat looking down to my left floor level, covering the window was a square piece of plywood with what appeared to be fuses and fusible links.  I told Paul hey!

You guys fix things like we do at the plant.  We both had a good laugh at that.  Multimillion dollar aircraft and the Govt. patches it with good old American know how.  Whatever works!

[DaveBB]

I worked with a former C-130 crew chief.  It is actually possible to overstress the aircraft just from giving it full power.  For some reason a C-130 had to go to full power from a very low power setting, and it required a major inspection.  Found a crack in one of the engine mounts after that.  If I remember correctly, the engines want to twist the wings upward, almost like they are on a swing.

[colmbo]

Found this on the C-130 prop:

How the 54H60 Prop System Functions.
The 54H60 propeller assembly is a constant speed, fully feathering, hydro-mechanical propeller. During aircraft operation, the 54H60 prop system has two distinct ranges, beta (ground) and alpha (flight) ranges. These ranges are differentiated by what component is controlling blade angle.

In the beta range, blade angle is controlled by the throttles from 0-34°, but in alpha range, the propeller governor is attempting to maintain a constant speed of 1020 RPM. Conversely, the alpha range is from 34-90°.

[flatiron1]

I have noticed that the throttle in b-17's does not control rpm like in ah2. I have to reduce rpm manually to be able to slow doen for landing. I compared it to ah2 and is definitely different.

[Golfer]

How do you mean?

You'll have a harder time slowing down with the prop pulled back than with it in a fine pitch (full forward)

There is a definite mismatch in engine sound but I've not noticed any such change. The engine noise makes one think you're pulling more power than you really are IMO.

[mikeWe9a]

What you don't believe what I was told by Air Force C-130 crew?  Kathy and Paul are good friends of mine.  Unusual that the wife is a Pilot and Paul flight engineer.

Btw Paul brought me back an American flag flown over their base in Iraq.  I've yet to pick it up........I'm lazy. I am trying to get in touch with them through operations

at the 910th at Youngstown Air Base.  Been so long I talked with Maintenance at the 910th and Paul is no longer there.  They may have retired, good for them.

Their Air Base: http://www.youngstown.afrc.af.mil/Home.aspx

I believe that there was a slight misunderstanding in the discussion.  C-130 crews use torque as their measurement when setting power, as that is the direct measurement of aircraft power.  The propeller, however, does not act to maintain torque - it acts to maintain RPM.  I have approximately 4,000 hours as a pilot in the EC-130H.  The propeller works to maintain 100% RPM when in flight, unless the engine is shut down, in which case it feathers to reduce drag.

Mike

[FLS]

I have noticed that the throttle in b-17's does not control rpm like in ah2. I have to reduce rpm manually to be able to slow doen for landing. I compared it to ah2 and is definitely different.

What's different is the sound. Reducing throttle works the same as it did in AH2 it just sounds different. Reducing RPM makes it sound like AH2 while performing differently.

[GScholz]

People who don't understand how rpm and power change the sound of the engine have never driven a stick shift...

[hitech]

You sure about this? This would mean the prop is not constant speed.

HiTech

I believe that there was a slight misunderstanding in the discussion.  C-130 crews use torque as their measurement when setting power, as that is the direct measurement of aircraft power.  The propeller, however, does not act to maintain torque - it acts to maintain RPM.  I have approximately 4,000 hours as a pilot in the EC-130H.  The propeller works to maintain 100% RPM when in flight, unless the engine is shut down, in which case it feathers to reduce drag.

Mike

Ahhhhhhhh I feel much better now, physics make sense again.

HiTech

[Scca]

I have noticed that the throttle in b-17's does not control rpm like in ah2. I have to reduce rpm manually to be able to slow doen for landing. I compared it to ah2 and is definitely different.

As far as I remember, the B-17 throttles never controlled RPM except after landing (just like they do now).  What you're hearing now is different, but the action in the air is the same....