FX3 options/recommendations for off-airport ops

[soyAnarchisto]

I have oil pressure during run-up, especially at 1700 rpm. It's definitely governing at that point. The question is what's happening with no engine firing, minimal rpm from airflow and therefore minimal to no oil pressure. I thought it was supposed to go coarse, but I don't know now. I'm here for the education.

If your prop governor doesn't work below 1800 how are you cycling your prop during run-up?

 

[stewartb]

I run it up at 1800. It’s been that way since the PPonk conversion.

I’d expect my prop to be flat at closed throttle and best glide speed. Engine out I’d expect the same. I can’t recall doing that exercise since my first PP check ride.

 

[frequent_flyer]

I have oil pressure during run-up, especially at 1700 rpm. It's definitely governing at that point. The question is what's happening with no engine firing, minimal rpm from airflow and therefore minimal to no oil pressure. I thought it was supposed to go coarse, but I don't know now. I'm here for the education.

Oil pressure is included in my recorded data set. My FX-3 oil pressure did not drop below 60 psi in any of the glide tests. Not a factor in my test results.

At best glide speed, with or without engine producing power, I would expect rpm to be high enough to give adequate oil pressure to operate the prop. That would change if aircraft slowed to the point the prop stops.

 

[stewartb]

Here's a Mac operations brochure. https://mccauley.txtav.com/-/media/...d prop uses,air- speed increases or decreases.

In constant-speed systems,
the pitch is increased with oil pressure. In full feathering systems, the pitch is decreased with
oil pressure.

 

[soyAnarchisto]

I expect the same - because that's how it works. However, at engine out I want the opposite - because I know how much drag is caused by the big flat prop turning. Vg is the speed for minimum sink, which happens at maximum L/D. Reducing drag may not change Vg, but it sure does change that lift/drag curve, which is important to extend your glide. It's so important that they designed the full-feathering feature into the props and reduce assymetric drag when a twin is trying to fly and maintain altitude on a critical engine.

According to the McCauley tech letter, the governor has a geared accelerator pump which further increases oil pressure stepped up from the engine oil pressure. So if the engine dies - and maybe if it was because of something that doesn't adversely affect oil levels or the mechanical gear pump - you might have enough oil pressure and accelerator gear pump pressure in the gov to allow the prop to increase the prop angle of attack for a low rpm condition.

So...back to the question of whether the prop/governor does this. I think the only way we will know that is to shut the engine off in flight. I'm not sure I've got the guts to try that. I know it should not be a big deal - we land gliders every day on my field - but they have lift spoilers and glider ratios of 2-5X of my cessna. I think I might try this with 3 or 4 thousand feet AGL over the field so I have more time to experiment and get the engine re-started just in case so I don't have to actually do the emergency landing.

All I know is in my plane, I want coarse pitch in an engine out - it will buy me A LOT more time and distance to have a more positive outcome in an emergency.

 

[frequent_flyer]

Vg is the speed for minimum sink, which happens at maximum L/D.

You need to spend some time with an experienced glider pilot! Min sink speed IS NOT best glide (max L/D) speed. Best L/D speed is always higher than min sink speed (assuming flight in a motionlesss airmass).

You can't change how your propeller/governor combination behaves. The best you can do is understand it and know how to best to manage it.

 

[frequent_flyer]

So...back to the question of whether the prop/governor does this. I think the only way we will know that is to shut the engine off in flight. I'm not sure I've got the guts to try that. I know it should not be a big deal - we land gliders every day on my field - but they have lift spoilers and glider ratios of 2-5X of my cessna. I think I might try this with 3 or 4 thousand feet AGL over the field so I have more time to experiment and get the engine re-started just in case so I don't have to actually do the emergency landing.

There is no need to kill the engine. Simply run the test I reported earlier. Establish aircraft at best glide speed with throttle idle and prop lever full forward. Note rpm and VS.
Pull prop lever to aft stop and note rpm and VS.

The only reason to kill the engine is to establish sink rate with prop stopped.

 

[Farmboy]

My O-360 with Hartzell governor and trailblazer prop will not cycle the prop at 1700. After Mag check I increase to 1800 to cycle it.

In the air if throttle is at idle or low mp then prop control does nothing - prop will not move from flat pitch. My glide is what it is and no more.


Sent from my iPhone using SuperCub.Org

 

[soyAnarchisto]

Killing the engine is the only way to positively verify that with some windmilling there is enough residual oil pressure to allow coarse/fine governing of the prop. If the prop stops completely, I expect it to go full fine (high rpm).

I am a glider tow pilot, but not a glider pilot. The important part of that is to reduce drag and maximize lift when you need to extend your glide - and that's my entire point for this conversation. Our most experienced glider pilots know exactly squat about constant speed props, especially with an engine out. Well that's not entirely true - my hangar mate is a DPE for both glider and powered operations, and even he couldn't definitely tell me if the prop would pull back to coarse in an engine out. But together we decided we would pull it back in my plane after I demonstrated to him how much of a difference it made to the power off 180 during my commercial check ride. It is a very dramatic experience as others with 180s and seaplane props can attest.

Anyway, I'm going to try and gather the numbers you suggest.

 

[skywagon8a]

My O-360 with Hartzell governor and trailblazer prop will not cycle the prop at 1700. After Mag check I increase to 1800 to cycle it.

In the air if throttle is at idle or low mp then prop control does nothing - prop will not move from flat pitch. My glide is what it is and no more.

Thank you, That's telling me that particular prop/governor combination is made differently than most of the earlier designs. Likely the governor output pressure is much lower than other governors. This in addition to there being a spring pushing the prop to low pitch. We learned something. That prop/governor combination will not allow the extended glide trick to work.

-my hangar mate is a DPE for both glider and powered operations, and even he couldn't definitely tell me if the prop would pull back to coarse in an engine out. But together we decided we would pull it back in my plane after I demonstrated to him how much of a difference it made to the power off 180 during my commercial check ride. It is a very dramatic experience as others with 180s and seaplane props can attest.

That doesn't surprise me as moving the prop to high pitch for extended glides is not taught in any flight training situation. In my case it was something I discovered on my own because I like to try different things to see what happens. Like completely shutting down an engine and stopping the prop to see how the plane glides. If you try this with a wood prop, be prepared to land. The time I tried it in a J-3 the wood prop would not start wind milling. No matter how far down the nose was pointed. The metal props did restart. Well the one in a T-craft did, but the one in a Swift needed some help with the starter.

Just for information purposes which doesn't apply to the props in the airplanes we are discussing. The Hamilton-Standard 2B20 props which are used on many of the small radial engines should be shut down in high pitch. This empties the oil out of the prop to prevent congealing in cold weather and prevents the oil from draining and being replaced by air. This changing to high pitch would happen at idle power/rpm but worked quicker around 1000 rpm. In turn, the engine was started in high pitch. It was important to cycle the prop several times before takeoff to purge air and fill the cylinder with warm oil. Failure to do so, could cause the prop to cycle during take off until the air was purged.

 

[supercrow]

I am a little surprised at some of the reluctance to dead stick an airplane. Done onto known conditions such as a good runway or water or snow surface it is a non event. Not suggesting others should do it but I have owned many airplanes in the last 50 yrs. Some with electrics and some without. All small single engine aircraft. Chiefs, Champs, J-3s- Super Cubs-T craft etc. I have always practiced dead stick landings with all of them on skis wheels and floats because with the prop stopped they do NOT sink and glide the same as with a windmilling prop. These are not planes with a constant speed prop. Always figured that there would be enough stress in a real world situation that I didn't want to add the feeling of an unfamiliar aircraft at the same time.Some produced less change that others. I have actually been forced to do the real unexpected no power landing on 3 occasions and fortunately had a place to go for 2 of them with no damage. The 3rd was damaged in a landing into a poor field after carb ice killed the little continental. Not putting this out there to suggest folks should practice these procedures but do suggest that there is a lot of peace of mind in knowing what to expect when things get quiet suddenly. I guess I think that if you are not shocked by something happening so suddenly that might freeze you up for a few seconds, you have more time to find a place to go or attempt a restart if possible?

 

[frequent_flyer]

I don't think that finding minimum controlled rpm requires a flight test. Next time I take the airplane out I'll run this test prior to the normal run-up and prop cycle:

1. Initial conditions - throttle idle; propeller control full aft
2. Slowly advance throttle while monitoring rpm - expect rpm to rise with throttle advance until a limiting speed is reached
3. Record the rpm and manifold pressure for onset of speed limiting
4. Slowly retard throttle while monitoring rpm - expect rpm to stay constant with throttle retard and then start to fall
5. Record the rpm and manifold pressure for end of speed limiting
6. Pull throttle to idle and set prop level full forward

If you run this test please do it after the normal prop cycle or at the end of a flight so there is warm oil in the prop.

I have one data point - A P-Ponk 182 with 3 blade Hartzell showed 1,180 rpm minimum governing speed for the ground test. Glide rpm with prop full forward was 1,500. Pulling the prop control reduced glide rpm to 1,180. Air not stable enough for a good evaluation of VS reduction.

Note that the minimum governing speed for this aircraft is way lower than for my FX-3's Trailblazer.

 

[soyAnarchisto]

My 1955 180 with a O-470JCR engine and the 88" McCauley prop

end of flight test - engine very warm
at idle, prop full coarse RPM is 692 and 13" of manifold pressure
slowly add manifold pressure, RPM rises to just over 1,000 rpm at about 15-16" of MP then stops increasing rpm.

So... I believe my minimum governing RPM is about 1,000 rpm. Maybe that's consistent with your p-ponk 182 data point. I only had time to do 1 test - I probably should repeat it a couple times to make sure I've got the numbers correct.

I didn't have a chance to really pay attention to the rpm/prop settings other than to say, when I'm in the pattern and abeam the numbers. I pull the throttle to idle with the prop full in - pitched at 75 indicated, the rpms still never drop below 1500. So the prop governor cycles pretty reliably all the way to the ground.

Way too busy in the pattern with student and parachute jumpers to consider the dead stick. Maybe someday soon.

If you run this test please do it after the normal prop cycle or at the end of a flight so there is warm oil in the prop.

I have one data point - A P-Ponk 182 with 3 blade Hartzell showed 1,180 rpm minimum governing speed for the ground test. Glide rpm with prop full forward was 1,500. Pulling the prop control reduced glide rpm to 1,180. Air not stable enough for a good evaluation of VS reduction.

Note that the minimum governing speed for this aircraft is way lower than for my FX-3's Trailblazer.

 

[Narwhal]

Great discussion, I will try the test in my FX3 (best glide with prop control full forward vs full aft) if the ceilings up here ever lift enough and I get a day off from work. I know we're not planning to do this: but I talked to one carbon cub FX3 ferry pilot who had some difficulty restarting an engine in-flight that was intentionally ran off one fuel tank until empty to extract maximum range. I'd definitely want to be overhead an airport with a long runway to account for my own shortcomings as a glider pilot if I were to shut an engine all the way down.

 

[frequent_flyer]

I will try the test in my FX3 (best glide with prop control full forward vs full aft) if the ceilings up here ever lift enough and I get a day off from work. I know we're not planning to do this: but I talked to one carbon cub FX3 ferry pilot who had some difficulty restarting an engine in-flight that was intentionally ran off one fuel tank until empty to extract maximum range. I'd definitely want to be overhead an airport with a long runway to account for my own shortcomings as a glider pilot if I were to shut an engine all the way down.

I have also heard a report of an FX-3 that was difficult to air start after single tank fuel exhaustion. I'm not convinced this is a concern for an intentional shutdown with the mixure control. In that case the fuel system remains pressurized up to the servo.

Not suggesting this is a zero risk test though, expecially for anyone who does not regularly use idle power approach to landing.

Data for the ground test would also be much appreciated. Only have one FX-3 data point and I'd like to know if my governor/prop is typical.

 

[hotrod180]

my 1955 180 with a o-470jcr engine.....

470 jcr??

 

[soyAnarchisto]

Yes. Continental engines can all be converted from one to another. My original engine was converted from a J to an R, and is now wearing a data plate that says JCR. It's an R now - it just wasn't always an R.

470 jcr??

 

[aflyer]

Data for the ground test would also be much appreciated. Only have one FX-3 data point and I'd like to know if my governor/prop is typical.

Today I ran the ground test on my EX-3, and got exactly the same results as f_f has been getting. I can't say I'm happy about it, I feel like a tool for controlling the glide in an engine-out has been taken from me.

 

[frequent_flyer]

Today I ran the ground test on my EX-3, and got exactly the same results as f_f has been getting. I can't say I'm happy about it, I feel like a tool for controlling the glide in an engine-out has been taken from me.

I have not run the ground test yet. Would you please report the results you observed. I'll keep track of the reports and publish a summary. Please include prop diameter.

 

[aflyer]

Hi Andy. I began with an in-flight test. I was cruising at 2300 rpm, at 9000ft msl. I pulled the power all the way to idle, nose down to 60 kts, and then pulled the prop control all the way back. Then moved the prop control all the way forward and back a few times. There was no response in rpm or airspeed or feel from the prop control changes. BTW 83" Trailblazer.

When I was an active instructor, I demonstrated this to many students. There was always a dramatic response to pulling the prop control back in a gliding airplane. So I knew this was different right away. But then, as I was testing so many things during my initial 40 hours of flying, I forgot about the prop/governor behavior until you posted your own findings.

Yesterday was just a fun flight down to Angel Fire with a friend who has a new Scout, also with a Trailblazer (80"). He also tried the run-up test with the same results. We each started at 1800 rpm, pulled the prop back and got the usual response. Then at 1700, and 1600, but at 1500 the rpm only went down about 10rpm, and below that no response at all. That was the only testing we did, both as we left KAXX with warm engines.

John

 

[frequent_flyer]

Yesterday was just a fun flight down to Angel Fire with a friend who has a new Scout, also with a Trailblazer (80"). He also tried the run-up test with the same results. We each started at 1800 rpm, pulled the prop back and got the usual response. Then at 1700, and 1600, but at 1500 the rpm only went down about 10rpm, and below that no response at all. That was the only testing we did, both as we left KAXX with warm engines.

Thanks for the report which seems to indicate a minimum governing speed of 1490 rpm for your 83 inch Trailblazer and for the 80 inch Trailbazer on the Scout. That is very close to the 1480 rpm I observed with my 80 inch Trailblazer.

The ground test you ran is not the same as I proposed in post 83 but it's likely it would give similar results.

 

[frequent_flyer]

I enlarged a general engine picture and cropped the governor installation. It's not a great photo but the adjustable (high speed) and fixed (low speed) stops are both visible.

I have said several times that the low speed stop of this governor is not adjustable. I took a closer look today and I may have been wrong.

The stop itself is not adjustable. It is an integral part of the governor end plate. The end plate has circumferential slots for the screws that secure it to the governor body. It appears that the end stop position can be changed by rotating the entire end plate. Any rotation to adjust the slow speed stop would require a compensating adjustment of the high speed stop.

Since several Trailblazers seem to have the same minimum governing speed I assume the plate location is set by Hartzell. I would really like to see the overhaul manual for this governor but I have been unable to find one.

 

[Narwhal]

I had a chance to do the tests. I'm sure I made a few mistakes but here is what I found:

83" Trailblazer on Carbon Cub FX3.

Ground Test: Minimum Governing RPM approximately 1400. Seemed to hold about 1420 RPM once passing 13" of MP on the way up as throttle was advanced. Coming down The RPM decreased slightly to about 1350 once throttle reduction was initiated, and held there until about 13" of MP.

Flight Test: Engine windmilled at 1100 RPM with both the prop control full forward or full aft with the throttle at idle. No change to sink rate which was about 900 FPM at the published Vg of 68 MPH IAS.

I did completely shutdown the engine to see what would happen while I was over an airport. Mixture to idle cutoff reduced the windmilling RPM to 900 but that didn't have a significant effect on sink rate at best glide speed. Then I pitched up to about 50 mph to stop the prop. This resulted in about 700 FPM sink rate at 68 mph compared to 900 fpm when the engine was windmilling at 900-1100 RPM.

Video evidence if anyone cares to watch. Sorry about the glare and dirty GDU-465 display. I should've wiped it down. One nice thing about the glare though is you can kind of see when I move the prop control in the tests. The big speedometer in the bottom right is groundspeed, and since there was a 15-20 mph wind out of the north it varies quite a bit even though I'm doing my best to hold 68 IAS.

 

[skywagon8a]

The stop itself is not adjustable. It is an integral part of the governor end plate. The end plate has circumferential slots for the screws that secure it to the governor body. It appears that the end stop position can be changed by rotating the entire end plate. Any rotation to adjust the slow speed stop would require a compensating adjustment of the high speed stop.

Since several Trailblazers seem to have the same minimum governing speed I assume the plate location is set by Hartzell. I would really like to see the overhaul manual for this governor but I have been unable to find one.

That plate location is determined by the airframe installation based upon the alignment of the push controls in relation to the control arm. On some governors the arm itself can be repositioned on the shaft to be aligned with the controls. Thus the stops need to be realigned to the arm.

While I can not address directly your particular governor, in general if you wish to further experiment, you can rotate that plate by the amount the low pitch stop screw protrudes from it's tab. This will give you a wider pitch adjustment range.

 

[frequent_flyer]

I did completely shutdown the engine to see what would happen while I was over an airport. Mixture to idle cutoff reduced the windmilling RPM to 900 but that didn't have a significant effect on sink rate at best glide speed. Then I pitched up to about 50 mph to stop the prop. This resulted in about 700 FPM sink rate at 68 mph compared to 900 fpm when the engine was windmilling at 900-1100 RPM.

Thanks for all the data you provided but this test result is the most valuable. A 200 fpm reduction in sink rate for stopping the prop would give a significant improvement in glide performance on a long glide.

Hopefully the extreme heat we are experiencing in AZ will break soon and I will be able to run this test myself.

 

[frequent_flyer]

That plate location is determined by the airframe installation based upon the alignment of the push controls in relation to the control arm. On some governors the arm itself can be repositioned on the shaft to be aligned with the controls. Thus the stops need to be realigned to the arm.

On this governor the control arm is splined to the input shaft. The spline is quite coarse but adjustment of one half the spline pitch can be obtained by reversing the control arm (inside face faces out). I had experimented with control arm position and cable adjustment trying to get full stop to stop control before I found the prop cable was defective. Changing the control arm position does not change the stop adjustment on this governor. The stop arm and bias spring are independent of the control arm. (I don't have an assembly drawing and may be using incorrect names)

While I can not address directly your particular governor, in general if you wish to further experiment, you can rotate that plate by the amount the low pitch stop screw protrudes from it's tab. This will give you a wider pitch adjustment range.

Yes, that adjustment appears to be possible but I won't attempt it without understanding what else would be changed. I think the plate provides the anchor for the bias spring and I don't know what is changed inside the governor if the plate is moved. Perhaps the most important thing to know is why these governors are set to approx 1400 rpm minimum governing speed.

I have emailed Hartzell support and will report if they provide any useful information. Thanks for your interest and comments.

 

[frequent_flyer]

Yes, that adjustment appears to be possible but I won't attempt it without understanding what else would be changed.

I found some photos of an S-1-10 governor in a vans thread here - https://vansairforce.net/community/showthread.php?t=56174

The final number is different but the Harzell part number decoder says this number represents "Minor Variation of Basic Design (numeric or alpha character) indicating variations of: RPM setting, head orientation, relief setting, rotation, lever angle, and/or minor part changes"

It appears to me that rotating the end plate would not have any influence of the high or low rpm settings. The extended length of the worm drive "pusher" won't change as the end plate is rotated, nor will the relationship of the stop arm to the high and low stops.

I'm left believing that minimum governing speed is defined by the final dash number and is not adjustable.

An assembly drawing would be more informative that the fuzzy photo but I think the photo is good enough to understand how it works. I've been wrong before though and would welcome any different interpretation.

 

[skywagon8a]

I found some photos of an S-1-10 governor in a vans thread here - https://vansairforce.net/community/showthread.php?t=56174
It appears to me that rotating the end plate would not have any influence of the high or low rpm settings. The extended length of the worm drive "pusher" won't change as the end plate is rotated, nor will the relationship of the stop arm to the high and low stops.

I do not agree. It appears to me that you can increase the total travel range of the governor's settings by screwing in the high rpm limit screw and rotating the stop housing counterclockwise an equal amount. This will keep your high rpm setting the same as you now have it while giving you the option of moving the control to a higher pitch setting.

The rotation of the arm only adjusts the compression of the internal spring as shown here. Rotating the arm rotates the helix spiral moving the pin resting on the spring. The pressure of the spring against the flyweight determines the amount of oil flow to/from the propeller.

 

[frequent_flyer]

I do not agree. It appears to me that you can increase the total travel range of the governor's settings by screwing in the high rpm limit screw and rotating the stop housing counterclockwise an equal amount. This will keep your high rpm setting the same as you now have it while giving you the option of moving the control to a higher pitch setting.

I agree that the total range of travel can be increased by screwing in the high limit stop screw. What I don't think can be changed is the worm drive (helix) extended length when the stop arm is in contact with the low speed stop.

How would rotating the end plate (stop housing?) influence the extended length of the worm drive? All the parts that control worm extension rotate together when the end plate is rotated.

edit to add - I think maybe I understand what you are suggesting. I'm assuming the end plate is one machined part that includes the female part of the worm drive. Only if the slotted end plate and the worm drive carrier are separate parts can the low speed stop be adjusted.

 

[skywagon8a]

I agree that the total range of travel can be increased by screwing in the high limit stop screw. What I don't think can be changed is the worm drive (helix) extended length when the stop arm is in contact with the low speed stop.

How would rotating the end plate (stop housing?) influence the extended length of the worm drive? All the parts that control worm extension rotate together when the end plate is rotated.

edit to add - I think maybe I understand what you are suggesting. I'm assuming the end plate is one machined part that includes the female part of the worm drive. Only if the slotted end plate and the worm drive carrier are separate parts can the low speed stop be adjusted.

I see what you are saying. I would need to have it in my hands to determine the correct answer. In other governors those parts are separate.