Building Mariah Gale

Vance

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Thank you Paul,

How well did the suspension work on the Aeronca Champs on a rough field?

There may be some very good reasons for doing aircraft landing gear the way they do it.

We want to try our way.

Our specific target is hard landings and takeoffs on a rough grass field.

We are down to 6 inches of travel and have a unique rocker that will provide roll resistance and allow us to use a single coil over and dampener.

We are planning on using 3 inches of real suspension and 3 inches of very soft spring and lots of compression dampening for hard landings.

Gill from works performance is going to make the custom dampener.

Or legs were completely redesigned on this trip.

We want to use the same aluminum wing strut that we are using on the front.

The push rods will be steel aero tubing although we have not ruled out aluminum.

Thank you, Vance
 

Vance

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Glad to have you along Gabor.

I look forward to updates on your project too.

It is fun to step out a little to accomplish similar goals.

I particularly like it when someone points out a weakness in our thinking like Mark did. It causes us to reexamine our process and if we continue to move in that direction we have a clearer picture of what we are trying to accomplish and what criteria we will use to scrap it and go with something more conventional.

It is frustrating how slowly things move.

We don’t want to back ourselves into a corner or do something that might endanger Ed and everyone working on this project has a life of their own that needs attention.

We will start at 4:00 AM tomorrow so I am off to bed.

Thank you, Vance
 

PW_Plack

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How well did the suspension work on the Aeronca Champs on a rough field?
I never landed or took off anywhere too rough, but I believe the point was durability on grass fields, and damping on slick surfaces. The plane in which I took most of my instruction was built in 1946, and was being flown by students over a thousand hours a year off a grass strip. Actually, perhaps that answers the question!
 

Resasi

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Any landing gear design that stands up to thousands of student landings has definitely been tested.

Those pieces are all looking very solid and nicely designed Vance.
 

StanFoster

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Vance- You sure have taken on a monumental task, but are tactfully taking small bites at a time, giving so much thought to each step. I noticed the neat MDF frame supports keeping everything going true. I just love observing techniques keeping frame components in order as they rise 3D off a 2D plan on the bench. Any more pictures of precise alignment jigs will be appreciated. I am in the front row with my hand raised annoyingly all the time. Ha. Brilliant thread , but what else would you produce? You are one of a kind Vance, and I can't wait to talk to you at Bensen Days , massaging some of those IQ numbers in your head, and hopefully picking up my IQ a number or 2! Stan
 

Vance

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That sounds good to me Paul.

I hope ours holds up as well.

It is one of those things that we must do.


Thank you Leigh,

We are pleased with the way everything is coming out.

There are things we would do differently if we were doing another one.


Thank you Stan,

I appreciate the kind words.

We are having a lot of fun.

Jim is definitely well suited to the odyssey as is Vince.

The jigs are wood and not strong enough to hold things in place.

They give us a plane of reference and a place to measure to.

They hold things in alignment so Jim can tack weld.

The precision of the parts comes from managing the finish welds.

Jim is good at using heat to move things and works from joint to joint to keep things in alignment as he finishes the welds.

Break is over, back to work.

Thank you, Vance
 

Vance

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My recent high wind experience combined with recent discussions on propeller slip stream has helped move us to decide to move the entire empennage back around six inches.

We feel that the effectiveness of the horizontal and vertical stabilizers goes up by at least the square and perhaps the cube of the increase in the distance from the center of gravity to the 25% chord line. We feel that the authority of the rudder goes up by almost that amount but don’t know where to measure from.

Based on Chuck’s Rotor performance this puts the horizontal stabilizer volume at 20.53% of the rotor volume

My new vertical stabilizer is 54 inches high. The one on the Predator is 65 inches high at the front and 43 inches high at the back.

The Predator is wonderfully resistant to torque roll and we want Mariah Gale to be as good in that department.

We feel the shrinking of the size of the propeller slip stream as it moves rearward will help the vertical stabilizer to straighten the slip stream of the 68inch propeller. We have a plan B to use strakes to manage torque roll if plan A does not suffice.

There are times at low power settings that I run out of rudder authority in a cross wind landing. We are hoping Mariah Gale will have a little more rudder authority and we feel the extra distance will help with the low power rudder authority.

We already had the structure in the keel and Vince just needs to put a couple of half inch spacers in his box to make this change.

Today I am taking the Ford E350 up to Greenwood to pick up the keel and taking it back to Hollister where I will spend the night and then work with Vince in the morning. When we are done I will take it back up to Greenwood because Jim is getting close to making the box that connects the main airframe with the keel and I don’t want him to be without it for long. We hope pictures will help with the interface and the final decision on the mounts.

The distance between Hollister and Greenwood is about 200 miles so it adds an extra challenge to cut and try design. The distance to Nipomo, 200 miles to Hollister and 400 miles to Greenwood by road, exacerbates this challenge. It is a beautiful drive especially in the Roadster and nice even in the E350 where I sit higher and have a better view.

The weather is supposed to be nice on Saturday so I hope to make it home Friday night so I can fly Saturday. Ed and I hope to fly Sunday.

Thank you, Vance
 
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MarkG

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The keel is mostly assembled and tack welded into place.

Jim hopes to finish it up before my next visit so we can match it up with the empennage.

The front is a little long so we have more options and we have a straight section for the lower tube, it is upside down in the jig, to mount the pivots for the suspension.

We worked on the design of the tail wheel mount and tail wheel suspension.

We both feel it can actually be lighter if it has some suspension instead of mounting it ridged.

We refined the design for the mount for the empennage.

We have the box that joins the keel with the main airframe designed and ready to go.

It has an extra brace on each side the goes back almost to the propeller.

The brace is not about strength but about raising the frequency that the keel and empennage resonate above what we imagine the frequency of the perturbation that is present.

The legs are straight so they can be faired individually.

The keel will be covered.

We have some extra length so we have options if things change.

Thank you, Vance

Vance

Something I learned from the Predator was the keel. The triangular shape is great for vertical and horizontal loads but does not work well for twisting loads. I suspect that your keel design the way it looks in the pictures without the top of the rudder anchored back to the airframe will twist very easily. I think that if you were to make the lower half of the keel out of 2 tubes instead of just the one to the shape of the upper tubes but inside of then diagonal brace the upper and lower together it would help a lot with the twisting. The sketch is crude but here is like what I mean....

 

Vance

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Great input Mark!

Great input Mark!

Hello Mark, thank you for the input.

How strong do you think the keel needs to be in torsion?

The tubing is 7/8 inch 4130 .049.

The brace that goes from just below the engine mount to just ahead of the propeller shortens the part that twists compared to the Predator. We also have two braces at the front of the box that connects the airframe to the keel.

We don’t have all the lacing on it yet so we have not tested it in torsion.

I would love to have a target for our test.

We don’t know how strong it needs to be.

I feel we can’t have a meaningful test until it is attached to the airframe with all the braces.

We don’t have the gaff at the top of the vertical stabilizer so it is what holds the empennage in place.

The top of the vertical stabilizer is about 57 inches above the top of the keel.

We don’t feel it is likely to fail but we would like to keep it stiff enough to keep the resonant frequency above the natural frequency of both the engine and the rotor.

We would be grateful for your input.

Hello Stan, you asked to see how Jim was keeping the frame straight and square AKA “precise alignment jigs.”

Here are some pictures of the frame table that is set up for the keel now but still has some of the blocks and notes on it for the airframe.

The funny bend in the top tube that will be on the bottom is so the pivot for the main gear can hinge straight.

I found a Cessna 172 wing strut and that is what we will make the lower suspension arms out of.

The pushrods with be 4130 aero tubing with a spherical rod end on the inside and a rubber shock bushing on the wheel side.

The part that pivots for steering and holds the nose wheel on Maria Gale weighs 1.5 pounds.
The XR 1000 on the stand was purchased new by a friend of Jim’s and his friend is having Jim restore it so he can give to his son.

I threw in the picture of the Indian Jim is going to restore for a friend because it is an example of the interesting things Jim has in his garage.

Thank you, Vance
 

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Vance

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The mission went well.

The mission went well.

The make sure the empennage fits the keel and move the empennage back mission went well.

We ended up moving the empennage back a little less than 6 inches and we feel we have frozen the design for the mounts from the empennage to the keel.

Vince has done some more work on the plug for the vertical stabilizer and rudder.

Once Jim gets the keel finished he is going to make a pattern out of wood that matches what he has done on the keel and send it to Vince so he can get things properly aligned and in the correct place.

We have gone to six bolts instead of four.

We have gone to three rectangular tube cross pieces instead of the tabs that are sketched.

I also got a Cessna 172 wing strut to make the suspension for the main gear out of.

It cost $15 and now I have a friend with a airplane junk yard.

The mission was 1213 miles over two days and a very nice drive.

Thank you, Vance
 

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StanFoster

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Vance- Thanks for posting pictures I requested. I owe you pictures in return. Tell me what you want to see. Stan
 

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Vance, buddy from a napkin to reality! This is so cool and professionally built. You can see the quality of workmanship, most excellent!

I have to admit this is exciting to watch, thank you for including us.
 

Resasi

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Wow!! That tail is looking really nice Vance.

Most impressive, and so much better than just putting on a Mooney one.
 

Vance

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Your welcome Stan.

All of your build pictures are an inspiration to us all.

You manage aesthetic detail so well.

I owe you more than I can ever repay.


Thank you for the encouragement John.

I feel so lost and confused sometimes.

The idea may look good in my imagination but when we try to turn it into reality it just doesn’t work out.

The landing gear on both ends is a departure from the original plan with less travel on the mains.

The tanks are now in the middle and hold less than intended.

It will be a big step when the keel joins the airframe and we mount the engine to do our center of gravity calculations so we can locate the main landing gear.

She may be up on her wheels by July.


Thank you Leigh,

I am very pleased with the work on the empennage and am satisfied with our mounting scheme.

I feel fortunate to work with an artist like Vince. Instead of chastising me for my indecision he got excited about how easy it would be to manage the change.

Jim is being very good natured about it too. The opportunity of moving the empennage rearward arose from a mistake I made in communicating with Jim what Vince and I decided about mounting the empennage. Jim kept rolling along with plan A and it needed to be changed. I am very pleased with plan E, 6 inches back. Jim thought that plan D, 12 inches back went too far and wouldn’t look right. Now the leading edge of the vertical stabilizer is about 18 inches behind the propeller.

Vince has to work on the empennage in his spare time and that makes planning difficult. He seems to be having fun.

The current plan appears to satisfy all of our design criteria for the vertical stabilizer, the rudder and the horizontal stabilizer as far as size and location. I don’t know if we can meet our weight goal. We will need to know what the empennage weighs before we can get her up on her wheels.

The parts you see are the plug for the mold. Where the vertical meets the horizontal will have a lovely radius. I don’t fully understand the process so we will all see it as it unfolds.

Thank you, Vance
 

MarkG

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Vance

I would say to check out some of the small aircraft around your airport. That would give you an idea of what they have for torsional resistance. The rudder and the vertical stabilizer will really be puting the twisting load on the keel. The prop wash will be side loading on it trying to twist it off as well as any time you use the rudder.
 

Vance

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Thank you Mark,

Thank you Mark,

I have not found an aircraft to compare Mariah Gale to.

The pusher aircraft I have observed have the propeller behind the empennage.

It appears to me the pusher gyroplane is the only one of that that has the vertical stabilizer directly behind the propeller.

All the tall tail gyroplanes I have seen have a gaff to steady the top of the vertical stabilizer.

It seems to me that on most gyroplanes the gaff holds the vertical stabilizer front to back rather than side to side.

It appears to me the Dominator gaff makes an effort to not provide left to right rigidity to the full flying tall tail.

The Predator’s vertical stabilizer seems to be held left to right by the gaff.

It appears to me only the horizontal stabilizer puts twisting loads into the keel on the Predator and that is below the prop blast.

Is that because the keel is not strong in torsion?

We are comfortable with the keel flexing; we just want to keep it from resonating.

I would like to have a number to design to.

Maria Gale will not have a gaff.

I would be interested in anyone’s opinion.

I would like Mariah Gale to work without a lot of development.

That is why she is so similar to the Predator; because the Predator works very well.

We are trying to reduce the two per rev shake so our mast is flexible and not stiff enough to support a gaff.

Thank you, Vance
 

Vance

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I don't know.

I don't know.

Vance, What is that C150 strut made of? Can you weld it without heat treating it? John K.
Hello John,

I suspect that the wing strut is from a Cessna 172.

I don’t know what model the one we used on the nose gear came from. It is fatter with a slightly shorter major diameter, sort of more round.

I feel both are something hard and heat treated because of the way it rings.

It is remarkably strong whatever it is made from.

We suspect 2024 which is not weldable, 7075 which is sort of weldable or 6061 which is weldable.

Cessna goes to a lot of trouble not to weld to the strut.

They use inserts that are riveted in place to manage the connection to the wing and tie down rings.

On the nose gear we are using inserts that are bolted in place for maintenance.

We will either bolt or rivet the ends on the main gear.

Jim is going to check and see if it is weldable because it might be fun to use an external gusset. I will report on his findings.

If we did weld it we would heat treat it afterward. I feel that heat treating increases the yield strength a lot.

Thank you, Vance
 

Vance

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A little more progress.

A little more progress.

The keel is complete with the six mounts for the empennage and all the lacing in place.

The mounts are made from square tubing with inserts and are flush with the top.

Jim sent Vince a wood pattern with holes in it so he could make the empennage fit the keel.

Any concerns about torsion strength evaporated as we tried to twist the keel.

We applied more twisting force than could be applied by the empennage mount and we were not able to deflect the keel a measurable amount in any direction.

We feel the entire airframe with the keel will weigh about 65 pounds. It is just a little over 16 feet long.

We discussed at considerable length how to attach the keel to the airframe.

We feel we have a satisfactory way to manage the connection with a minimum of drag.

As usual we are overbuilding everything.

It looks like the main gear is going to work out well.

We feel we found a better way to manage the root of the suspension and are looking forward to implementing it.

We are going to need to get serious about balance before we locate the mains.

Thank you, Vance
 

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