More fun flying The Predator.

[Vance]

These bearings always puzzle me Eddie.

I inspect and lubricate the bearings every 50 hours when I change the oil.

These bearings have 150 hours on them and when I inspected them at 100 hours there was no evidence of wear.

They had the matt finish of a happy bearing.

On my recent flight to El Mirage the cyclic seemed particularly smooth.

The cyclic seemed smooth on my last training mission with a 210 pound client in the back.

There are times when the stick shake is annoying in The Predator.

I was disappointed I didn’t get to test fly the new set up.

I had inspected the cheek plates the day before and did not find the crack. I only flew two point two hours since the last preflight.

Sometimes my clients wonder why I inspect her before every flight.

There was no evidence of any other cracking anywhere on the cheek plates.

I suspect this crack would have taken a long time to go anywhere because it went from a nicely finished hole to the edge.

It was not a theory I wanted to test.

 

[eddie]

Perhaps the tempering of the inner race was just a hard thin outer shell and when the needles wore through to

the softer metal it went very fast and also perhaps the extra weight of having a student with you helped with the wear,

other than that I haven't a clue.

I have never seen wear that bad except in u-jpints that were run dry for a really long time.

Its go's to show how important preflight inspections are.

 

[Kolibri]

There are times when the stick shake is annoying in The Predator.

Seems significantly inherent to a rigid one-piece mast.

I have had a lot of trouble with my needle teeter bearings brinelling from the beginning and take them apart to lubricate them with special helicopter grease every fifty hours.
They typically look rough after about two hundred hours and I usually replace them with less than three hundred hours.

They have high molecular weight plastic shims to control side play and even brand new needle bearings aren’t very tight.

I suspect that your original system had a lot of axial play from the thick plastic shims.
Also, your needle bearings may not have been of appropriate size or quality for the weight.

Sport Copter's 11,000 lbs. static load is per side, meaning 22.000 lbs for the pair.
3G in max gross weight isn't even 20% of that. Level flight is about 6% of static load rating.
Plenty of excess strength. SC owners don't complain about brinelling.

Their "300-500 hours" is their recommended replacement interval, coinciding with gimbal bearing replacement.
Actual service life is even longer. For example, their 2-seat tandem trainer with 1800+ hours has had needle bearing towers for 1000+ hours of that.

To extend life of the hats, rotate them a quarter turn every 50 hours or so.
I.e., don't let them set on the the same portion for their entire service period.

Readers interested in needle vs. spherical bearings in gyro teeter towers can refer to the discussion beginning at:
https://www.rotaryforum.com/forum/e...748-hub-bars-with-coning-angles-vs-flat/page4

 

[Vance]

The Predator doesn't have a one piece mast.

The Predator doesn't use hats.

The hats didn't last very long so I replaced them with a proper inner race as can be seen in the picture.

The setup I have is very common and works just fine as long as I lube the bearings every fifty hours and replace them every three hundred hours.

They used to last five hundred hours before I started training in The Predator.

She flew nicely before I took her apart this last time and simply replacing the bearings would have been simple and inexpensive; not much more work that lubing the bearings.

I feel it will be interesting to see how the spherical bearings compare.

Thank you Jake for a very nice job on the towers.

 

[Vance]

The Predator is flying again.

I finished her up at 4:00 this afternoon and went for a maintenance flight.

I am not a professional mechanic and expected to have some minor maintenance and adjustment issues. I was pleasantly surprised with how well everything worked.

It felt good to get back in The Predator after three weeks and Santa Maria ground welcomed me back.

I did a high speed taxi getting the rotor up to speed so there were no surprises and then took off half way down the 8,000 foot runway.

The new cheek plates/upper rotor tower seems to be working well.

The new teeter bearings seem much more precise and it appears I have less stick shake although I will need to do some testing to get a better feel for that. It has changed the feel of the cyclic.

I have been training in an RAF in Carson City for a week and I missed The Predator, Santa Maria Public Airport and the control tower.

I still need to clock the push to talk button on the front cyclic to the left.

I have a new linier actuator coming to help with stick forces when taxiing. It is going to be a project because the mounts are different. I spent several days looking for just the right linier actuator and found it at Progressive Automation in Canada. Turns out I lucked out on my shorter linier actuator and I couldn’t find the same one with a 200 mm stroke. I hope to have it in my hands next week.

I need to grease the nose wheel and perform some other minor maintenance.

I am pleased to be back in business.

 

[Vance]

No Title

An extended test flight in The Predator.
I wanted to see the difference the new rotor towers, spherical teeter bearings and cheek plates made and three times around the pattern was not enough flight time to be certain of what I felt so the next day I headed off to San Luis Obispo for lunch. This is one of my favorite flights and no two are the same. I checked the weather and winds were expected in the afternoon.

When I road raced motorcycles and I was trying different setups on the motorcycle I found it best to not think about the why of it and just focus on what I felt. We would time the laps and I would write about my impressions in each turn. It was the only way I could separate my expectations from reality.

I find it easy to fool myself that something I have done made the expected difference so I was trying to approach it as though I didn’t know that any changes had taken place and I did not try to figure out the why of it.

The first thing I noticed was the stick didn’t kick back when I pressed the pre-rotator button. Typically if I am not full forward and right the cyclic kicks back when the starter engages. I was a little careless the first time and did not have the stick hard right. The second time I intentionally was not hard right and it seemed benign. I only made two takeoffs so this could be an incorrect impression. This would be a nice change because the procedure is seemingly nonsensical and not common to all gyroplanes so I don’t like teaching it.

My impression on takeoff was The Predator moved through 180 to 220 rotor rpm with less shaking in the cyclic. Sometimes when I rush the rotor on takeoff the cyclic moves in a circular motion. This seemed noticeably absent. I wrote it off to my being more careful to get a feel for the cyclic and perhaps rushing the rotor spool up a little less. I teach my clients to not rush the takeoff so this won’t make a much difference except in gusting winds.

I climbed to 800 feet MSL (550agl) and took all the trim out to cruise at 60kts. Usually I have a bit of trim in even solo for 60kts and with no trim she is typically trimmed for 70kts. This made no sense but I vowed to explore it further.

I was snapped out of my test pilot mode by the beauty of the Santa Maria Valley with the Pacific beckoning in the distance. I set a course to overfly Oso Flaco Lake and as I drew near the shore line I first found some sink and then some rising air. The ocean air swept over me. As I reached the shore line I was still a little high so I pulled her to idle and listened to the swish of the blades as I descended nearly vertically to 500 feet.

The curved shoreline drew us north and I began making my radio calls. I could see Point San Luis and Avilla Bay in the distance as I floated toward the sea.

I made my first Oceano CTAF radio call. “Oceano area traffic; White Gyroplane Two Mike Golf, five miles to the south; transitioning north along the shoreline at 500 feet and 50kts Oceano.” I heard a call form a Cessna crossing runway 29 at Oceano before I made my three mile south radio call.

The on shore breeze had her pointed out to sea as I made my way north enjoying the breaking waves and deeply breathing in the ocean air.

At a mile and a half the Cessna at Oceano announced lining up for takeoff with a left cross wind departure to the south. I told him I would move inland and make a right 360 awaiting his departure. The timing was perfect, one two minute three sixty and I passed behind him. He reported southbound; gyroplane is sight as I waved and he rocked his wings; two pilots sharing our special world.

I checked the ATIS and called San Luis Obispo ATC over Shell beach. I was to call when turning final for runway two niner. I explained I was coming in through the Avilla Pass and was to left traffic for runway two niner and report downwind mid field for runway two niner. I am blocked on radar in the Avila Pass because of the hills.

I couldn’t tell if the stick was any smoother although it felt somehow better as though I was more directly connected to the rotor. I felt more aware of the turbulence as I made my way through the Avila Pass and I still had very little trim in and the control stick pressures seemed lighter. The winds were changing rapidly and the wind sock showed a tail wind as I touched down despite the wind check on final of 240 degrees at 11kts. I try to land near a wind sock to have fewer surprises.

I taxied to restaurant parking and the people from ACI Jet chocked all three wheels.

After a nice lunch I headed back to Santa Maria and I experimented some more. I did not learn anything definitive other than I feel the stick shake is acceptable one up and smoother in a vertical descent. It was a little windy to be doing steep turns so I left that for another time.

As I over flew the Santa Maria Valley and called ATC I found winds were rapidly changing at SMX. They changed several planes from runway three zero to two zero and back again. There was a heavy fire bomber coming in from the Woolsey fire and runway two zero was a little short and narrow for him so he was cleared to land on runway three zero. I was instructed to make right traffic for runway two zero and report turning base. ATC was trying to keep runway three zero clear for the departing fire bombers.

I landed about 100 feet past the threshold well before crossing runway three zero and the tower said; “nice job Vance, if you want; just make a one eighty there and turn right on alpha and taxi to parking.” It was a lovely end to a lovely flight. It felt good to be back at my home airport where they know my name and the capabilities of The Predator.

 

[Kolibri]

Really glad to hear that you have replaced the out of date needle bearings with spherical ones

eddie, needle bearings are not "out of date". In fact, they are exactly the bearing of choice for teeter towers.
They merely have to be of sufficient size and quality, and thereafter lubed regularly with Aeroshell 14 grease.
Vance's original needle bearings seemed too small, hence their short life.

______
These new bearing are not roller bearings, but spherical bearings as used in rod ends?
I.e., a steel ball drilled through with a 3/8" hole with milled flats on two opposite sides, secured within a 1" housing?

 

[Vance]

No Title

Please see post 539 where I explained exactly what they are, how they are mounted and the reason for them.

In my opinion what Kolibri describes would not work and I would recommend not using spherical bearings with a 3/8 hole for teeter bearings in a heavy gyroplane.


Jake did a very nice job on the design and fabrication.

They appear to me to be working very well as is the upper mast.

Time and testing will tell.

 

[gyrojake]

No Title

This is the set up.
These take more axial and radial loads than a little needle bearing and no chance of brinelling.
There is no wear on the tower sides from plastic washers, there is no right to left play eliminating right to left sliding and hammering of the rotor.
they are 1/2" wide and are bored into 5/8" plate with an 1/8" race stop on the inside and have a 1/2" I.D.
These are more precise and have no play in any direction.
If ya don't like em, don't use em.
If ya like em, the part number and specs are pictured for your use.
Thank You Vance for allowing me to be a part of your adventure.

Part # MS14102A-8 BEARING

 

[eddie]

Really a nice setup Jake, they will last forever and will work perfectly.
And once again kolibri the great is as usual shooting is mouth
off about things he has absolutely no knowledge of.

 

[Vance]

Thank you expanding the scope of the thread Jake; nicely explained.

I didn't know if you wanted me to reveal the specifics so I didn’t.

Everything went together beautifully and to me they look nicer than what I had.

The apparent changes in the flight characteristics have me puzzled; it is all good.

I will endeavor to become confused on a higher level.

I am going to do some more flight testing today and I have a primary student tomorrow.

If the effect on the trim is the same two up I may not want to go to a linier actuator with a longer throw.

I am going to work on finding a rotor balancer with a skilled operator.

I may try some hit or miss centering adjustment just to get a feel for where I am.

Thank you for helping me to enhance my gyroplane adventure.

 

[Kolibri]

they will last forever and will work perfectly.

Either would be a first in aviation. :smile:


____
I looked into this, and, as I suspected, spherical bearings are not meant to be used for teetering.
It's actually acting more like a bushing than a bearing.
I expect you'll soon enough experience some odd wear in them.

But, I agree with what Vance wrote, "Time and testing will tell."


____
I think that needle bearings have unfairly received a bad rap in this thread, and another.

However, Chuck believes them appropriate for teeter towers:

There is no excuse tor not following standard helicopter practice and using needle roller bearings;
needle bearing inserts are inexpensive and readily available in appropriate sizes.

A rotor in flight, Eddie, teeters ~3 degrees each way for a total of 6 degrees in the upper speed range.
With full compliment needles, that’s more than enough for each roller to overlap its neighbor’s track; therefore, no brinelling.

Wonder why someone didn’t tell the designers of teetering rotor helicopters such as the Bell-47 and Robinson
that needle bearings wouldn’t work as teeter bearings?

 

[gyrojake]

Either would be a first in aviation. :smile:

____
I looked into this, and, as I suspected, spherical bearings are not meant to be used for teetering.
It's actually more of a bushing than a bearing. I expect you'll experience some odd wear in them.

But, I agree with what Vance wrote, "Time and testing will tell."

Well, you need to check your sources!!
Some Helicopters like the Robinson use them in the tail rotor assembly for feathering and the delta hinge, which teeters at a much higher frequency than our main rotor .
The mini 500 use them as teeter bearings in the rotor head.
Your source is flawed ..........................why am I even trying to explain
Did you even look at the specs?
14,950 lbs of oscillating radial load.
That is rated 10x more than the AUW of Vance's machine.
It's good for 100,000 cycles at 21,000 lbs !!!
Don't think much will happen under normal or extreme flight conditions,

 

[Kolibri]

I'm not arguing about the strength of the part, but its application as teeter bearings for such a heavy gyro as the Predator with its 8.5"x30' Sport Rotors.
That's a much different kind of load than a small helicopter's tail rotor.
A control load (of, say 50lbs) is much different than a carrying load.

Yes, the part seems amply strong for the task and won't likely fail/break apart, but that's not my point.
I suspect that play will develop in the Teflon lining, exhibiting as stick shake.
Thus, I do not believe that it's a "forever" solution. Not trying to rain on anybody's parade.

It will be interesting to revisit this 100 or 200 hours hence. Meanwhile, good luck!

Regards,
Kolibri

 

[Vance]

No Title

The last time I flew with a client I had a shimmy in the nose when he landed with too much speed and dropped the nose a little hard.

I use dielectric grease as a shimmy damper and some fresh grease took about ten minutes to apply.

I have a client coming and I always do a maintenance flight before flying with another person.

We have some rain coming and I could feel it in the air.

The recent rain has cleaned the air of the smoke from the fires and the air felt fresh and clean on my face.

The sun was setting and I did two normal landings at less than five knots and decided to test it properly and set her down on the final landing at fifty knots and planted the nose. She rolled out as nice as could be.

I love the way the airport changes as the sun sets.

I have yet to find a way to not have fun flying the Predator.

Even this simple flight felt magical to me.

 

[Vance]

No Title

It has been a while since I wrote about the fun I have because I have been very busy. I have several stories saved up and will try to finish them up as I wait for paint in Buellton.

Jelena from Bosnia called me up speaking with a most charming accent and asking for gyroplane flight instruction. She had a FAA student license and that addressed the transportation security authority challenge.

I never know what to expect when someone tells me they know how to fly a gyroplane. A few have elicited trepidation as I recovered from untidy maneuvers.

Jelena was great from the start. She listened well and asked good questions. She is fiercely intelligent and it showed in everything she did.

It was still smoky from the fires.

Her experience had all been in an MTO Sport and she was happy to fly from the back seat so off we went to the practice area. After very little adjusting to the aircraft and very little coaching from me; she flew to commercial practical test standards and did all the maneuvers well.

She was a delight to fly with and her friend did not speak English. Jelena is the tall one standing toward the front of The Predator.

It was a lovely way to spend the afternoon.

 

[Vance]

No Title

I am the crazy uncle for my niece Claire so I understand the crazy uncle thing. Everyone should have a crazy uncle and Lillie Lemon’s is Jim.

I have an all-day deal where we fly to San Luis Obispo for lunch and do enough flying to land. Jim wanted to add Lillie and as a flight instructor it is more challenging to address too people with different agenda’s.

Jim is a widely traveled adventurer (crazy uncle) and Lillie Lemon is a talented musician into Indie Electro-Pop. I didn’t know what it was so I listened from her Facebook page and I liked it. Lots of energy.

Jim wanted to find out if he wanted to make the commitment to fly gyroplanes and Lillie was hanging out with crazy Uncle Jim and knew whatever he did would be fun.

We worked through preflight and the briefing and both asked good questions.

I took Jim up first and he did well. We had some work to do on the ground reference maneuvers. He seems fearless and took instruction well.

He wasn’t quite ready to land. He had forgotten how to lower his face shield and the wind in the back seat caused his eyes to tear up and coat the inside of his glasses with salty tears. He was also having a little trouble hearing instructions over the intercom.

Lunch was the next challenge because they were both vegans. Fortunately near the airport is the Natural Café so off we went for a nice lunch.

After lunch it was Lillie’s turn and she did as well as any inexperienced gyroplane pilot I have flown with.

Conditions were not ideal and Lillie’s hands became cold enough to lose feeling in them. I had gloves on board but she didn’t know to ask and was not comfortable flying numb.

Jim improved dramatically on his second flight learning to work the face shield and tighten up the helmet strap so he could hear me better. By the end of the lesson I felt he was ready to land and it was a good one with very little coaching and little input from me.

He was trying so hard he may have forgotten to have fun.

I hope Jim will be back; he listens well and is fun to instruct.

 

[loftus]

Some interesting people. Thanks for the stories Vance.

 

[Vance]

Part of what makes giving flight instruction so much fun is the amazing people who want to learn to fly a gyroplane. I only scratch the surface in my reports.

The ring gear on The Predator’s pre-rotator came to the end of its service life at 2,261 takeoffs. I carefully measured it and counted the teeth only to find the distributor didn’t have any. I cast about on Google and found one at Pep Boys and ordered it from the Pep Boys store in Santa Maria Tuesday 12/11.

Miracles of miracles the correct starter ring gear for The Predator pre-rotator showed up at Pep Boys today; 12/12 and tomorrow I am hoping to install it and begin reassembling the rotor head to get The Predator airworthy again.

The Predator also has a broken body mount to repair and Max has agreed to do it tomorrow. It seems no matter how many times I say the body is not structural clients still hoist themselves up our of the seat by pushing on the body leading to failure of the body mount.

I hope to be flying again by Saturday evening although somehow it always takes longer to put her back together than it does to strip her. She will be ready when she is ready.

 

[Vance]

It seldom comes easy.

The ID of the ring gear turned out to be .030 smaller than the one that was on there. It was impossible to measure the old on when on the center and once we had cut it off the dimension had changed. Jim and I worked on it till 1:00 trying to get it to work.

Richard at the airport did a lot of guessing and machined the inner aluminum hub down so we had .011 interference fit. We heated the gear in his oven to 375 degrees and cooled the inner with dry ice and it dropped on as nice as could be.

I called Smokey who has a lot of experience with such things and when he called back when he returned from lunch he recommended .010 to .015 interference fit. He also recommended 375 degrees heat on the ring gear. We were going to use 250 degrees.

The rotor head is back together with the spindle bolt properly torqued and the rotor bearings inspected.

The assembly is installed on The Predator with fresh grease on the pitch pivot. This was in surprisingly good condition and needed no adjustment shims.

The control assembly is assembled and hooked back up and the sender for the rotor tachometer is on, hooked up but not yet adjusted.

The mechanism for the trim is in place but the spring is not yet hooked up.

I stopped at 5:00 when the light failed, the work is too critical to rush or do without good light.

Tomorrow's plan is to install and wire the starter, put the towers and teeter back together, install the rotor blades and install, hook up and adjust the rotor brake.

I am looking forward to testing everything.

Max was slow getting over his cold today so he is coming tomorrow to fix the body mount. Max is 78.

He is so good he thinks it will be easy despite the close proximity of many combustible things and challenges with keeping it properly aligned. He has a special small TIG torch and has a scheme to keep everything aligned.

I could possibly have her flying by Friday evening. Saturday is more likely.

I had a lot of very talented help and it was fun working with them today.