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A full composite Mooney. Possible or not?


Cargil48

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Yes, of course you can build a Mooney out of composites.  I don't know why you would want to, since the composite construction will allow for more compound curves with greater aerodynamics.  Of course the biggest hurdle isn't building it, but getting it certificated through the FAA.

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3 hours ago, Yetti said:

I will never ride a carbon frame,  I had one early on.   I ride Ti frames and Seats with Ti seat rails.

If you can afford it... 

What makes me wonder is if there is no significant weight advantage and even danger using carbon fiber when severe impacts occur, then I ask myself why are ultra-fast Formula One cars almost fully made of exactly that fiber? And boy, we do sometimes see severe hits in those races... Okay, those small parts of the front wing flip off upon the slightest impact, but... they are small and I guess with not enough "critical material" to sustain impacts. But when there are lateral impacts wheel against wheel I do admire the wonders of today's technique regarding the stiffness of those carbon fiber suspension parts! 

Back to topic. I agree that the biggest advantages of composites in aviation are lack of corrosion danger and ease of assembly (less work hours in big parts). But why then Boeing (and others) insist on that weight saving thing??? And we know this is a strange topic, since yes, the SR22 is heavy for a plane of that size... The same occured with the failed M10T project... So what explains this discrepancy?

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1 hour ago, steingar said:

Yes, of course you can build a Mooney out of composites.  I don't know why you would want to, since the composite construction will allow for more compound curves with greater aerodynamics.  Of course the biggest hurdle isn't building it, but getting it certificated through the FAA.

If so, how did Cirrus manage to do it?

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Final thinking: 

Reading this utmost interesting article https://www.compositesworld.com/articles/thermoplastic-composites-primary-structure  one idea pops up: Creating a company with several of those synchronized robots (as they say in "Composite World" costing each around $ 100k or so) and produce parts for several aeronautic customers: Piper, Cessna, Beech, Gulfstream, etc., etc. Each brand would then make the assembly ast their own wishes.

This is it, I have no knowledge to go any farther. Just got the idea to question the Ifs and look at the outcome. And no, it's not "dreaming", all this is the very near future...

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1 hour ago, Cargil48 said:

Back to topic. I agree that the biggest advantages of composites in aviation are lack of corrosion danger and ease of assembly (less work hours in big parts). ...

This is false as it turns out, as counter intuitive as it may seem.

I used to own a Diamond DA40 and to my horror - my composite wing developed a case of corrosion!  It turns out that the composite wings need have a metal scaffold embedded into the surface of the wing to wick electricity in the clouds, as part of an IFR certification.  In the case of Diamond DA40 at least, there are dissimilar metals used to screw some parts down to the rest of the wing, and these act as a catalytic source that allows the scaffold to corrode.  Then you get bubbles in the wing...and the solution is called "scarfing" an ugly word and an ugly process where they take the wing off, scrape off lots of material and reapply material etc...at much greater expense than say replacing a wing skin on a standard metal wing.  Why they would use cheap hardware on a composite wing is beyond me but that is what they do.  I think this can happen in any composite structure that is meant to mate together with metal parts.

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4 hours ago, Yetti said:

Babbling is what we do here at Mooneyspace.    I have watched carbon fiber from the bike frame/wheel aspect.    Two observations with carbon fiber construction.   There are usually weight limits to make light carbon fiber components.    When carbon fiber fails it fails dramatically. This is a great story about aluminum being destroyed, but retaining shape to make it to the ground.  There is another story about the pilot making it to the ground and the wing being completely wrinkled. This one will do to.  https://www.aopa.org/news-and-media/all-news/2006/march/01/never-again-online-denalis-rough-ride

I will never ride a carbon frame,  I had one early on.   I ride Ti frames and Seats with Ti seat rails.

I have been deeply entrenched in the bike world since a teen.  I used to ride track and still sometimes ride in road tt.  I hear you regarding carbon failures can be scary.  But so can metal failures.  I have seen aluminum frames fail - on track on other riders.  I once in the late 80s had a steel frame fail on me in a sprint in a criterium and ...that was fun and lots of road rash thankfully not worse.  I have had 4 different cranksets fail on me over the years - 4 catastrophic failures where literally the crank arm broke in two.  One of them was a titanium crankset that failed at the weld - as they say, a chain is only as strong as its weakest link.

I too ride Ti frames for many reasons - but most of all I enjoy them.  I have 3 different ti bikes, one road, one mtn and one tt.  They are all over built and double welded.

Still on those ti framed bikes I have carbon wheels.  So carbon wheels can be just as dangerous as al wheels or a carbon frame if poorly built, poorly executed and poorly designed.  Or vice versa if well engineered.  I have "Edge" (company name) wheels built for "clydesdale weight" (as I am), and one set I have is 12 years old and going strong they are superbly designed and executed with the best materials.  On the other end of the scale - do you remember spinergy wheels?  They were poorly built, poorly designed (allowing for zero fault tolerance) and A LOT of people lost teeth (literally) when these wheels failed.  http://express-bike-shop-609858.shoplightspeed.com/spinergy-rev-x-700c-carbon-rear-wheel.html

My middle son is my height and at least as strong as I was in my hey-day (probably more so!) and he rides a cervelo carbon fiber bike and he is 200lbs (my college weight was that too), and puts out 1600 watts in a good sprint (measured by power tap pedals) and I am fully confident in his riding that carbon bike.  Same bike for 4 years now.  On the other hand he broke a wrist when his shoe cleat failed.  Ironically I broke a thumb in college when my shoe cleat failed.  A chain is only as strong as its weakest link.

I also row  and a latest and greatest scull at 27' long is only about 30 lbs, including hardware.  Which is amazing for such a big boat of carbon fiber and a beautiful "shell".

Whats my point besides replying to your bike comment - I have complete confidence that a carbon fiber (or other composite) airplane can be designed properly engineered to have appropriate strength, longevity and quality and probably also sufficiently light, for the strength requirements, but the one more dimension is cost - and I don't know.

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5 minutes ago, aviatoreb said:

Whats my point besides replying to your bike comment - I have complete confidence that a carbon fiber (or other composite) airplane can be designed properly engineered to have appropriate strength, longevity and quality and probably also sufficiently light, for the strength requirements, but the one more dimension is cost - and I don't know.

I agree with this statement.   I also believe carbon fiber has limited life.  And the not knowns outweigh the knowns as far as design limits.   CF has gotten much better over the years, but do you really want to fly a CF wing from 12 years ago.... nope.

CF rims are fine except when you hit them on a pot hole.   As you probably aware, most of the the work in a wheel is the spokes.  do you remember Rolf wheels and his higher that normal spoke tension.  and lots of pretensioning in the build process.  I agree with his theory.   Also I tie my spokes in the old school way.  Which causes the load to be shared between 2 spokes. but it takes away some of the suppleness of the wheel, so the trick is to tie the rear and leave the front un tied.  I have built wheels that go for years without needing a spoke wrench.  And of course surpass the Clydesdale class and on into the Yetti class at 250lbs

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1 hour ago, Yetti said:

I agree with this statement.   I also believe carbon fiber has limited life.  And the not knowns outweigh the knowns as far as design limits.   CF has gotten much better over the years, but do you really want to fly a CF wing from 12 years ago.... nope.

CF rims are fine except when you hit them on a pot hole.   As you probably aware, most of the the work in a wheel is the spokes.  do you remember Rolf wheels and his higher that normal spoke tension.  and lots of pretensioning in the build process.  I agree with his theory.   Also I tie my spokes in the old school way.  Which causes the load to be shared between 2 spokes. but it takes away some of the suppleness of the wheel, so the trick is to tie the rear and leave the front un tied.  I have built wheels that go for years without needing a spoke wrench.  And of course surpass the Clydesdale class and on into the Yetti class at 250lbs

Yes - I would fly a 12 year old CF wing.  Depends on who built it.  The technologies were excellent already as of 12 years ago.  For example I would happily fly a 12 year old Diamond airplane.  But as I said I wouldn't want to own one for maintenance reasons since as I said those wings can corrode even though they are (mostly) composite.

Yetti class - haha...love it.  I am simply a Clyde - at (currently) 218lbs.  But as such I don't ride stock wheels.  All of my wheels are custom built - with careful tensioning, and extra spokes.  The spoke wheel is an amazing engineering design with extra redundancy and usually mild failure modes.  Certainly I have wrecked wheels in pot holes but never heard of one failing that way catastrophically.

EVERYTHING has a finite life.  The goal is also to have predictable and supervised degradation as it ages.  I would fly in a WWII DC3.  I wouldn't want to own one - too expensive - but I would definitely fly in one. Yet AL does have a nasty and abrupt failure mode.

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2 hours ago, Cargil48 said:

If so, how did Cirrus manage to do it?

The Klapmeier brothers started out as kitmakers, if I recall correctly.  Thing is, when they did their thing just about everything was made from aluminum.  A fiberglass airplane was very, very new, and the parachute didn't hurt either.  My guess is they used their expertise in composite aircraft construction to leverage financing to start their company.  Someone had deep enough pockets to get them through certification and why not?  The Cirrus outperformed practically everything, and have truly ruled the roost ever since.

Even so, I seriously question whether they've ever turned a dime of profit.  They've gone from one owner to the next, and like Mooney are currently owned by the Chinese.

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Composite structure repairs are challenging and costly, indeed. Attached picture is of Columbia that recently overrun the runway at Lake Chelan, (S10).

Plane was totaled by insurance company due to repair cost, it  needed a new wing.

IMG_4607.JPG

IMG_4608.JPG

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4 minutes ago, Igor_U said:

Composite structure repairs are challenging and costly, indeed. Attached picture is of Columbia that recently overrun the runway at Lake Chelan, (S10).

Plane was totaled by insurance company due to repair cost, it  needed a new wing.

IMG_4607.JPG

IMG_4608.JPG

I see it also needs a new engine.  Is the damage more prevalent than the wing tip?

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Yeah,

Log is a giveaway, it did have a prop strike and NG damage. I spoke to the ex-owner and majority cost was in the new wing so insurance co. said no repair is cost effective. He took the money and bought a newer model.

I mainly posted it so anyone can see how does composite wing structure looks like.

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17 minutes ago, Igor_U said:

I mainly posted it so anyone can see how does composite wing structure looks like.

What's the opinion of you guys would probalby have happened if the wing would have been made of metal? Wouldn't it have affected (bended) the main and the secondary spar?

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I think the real value of composites is in the area of drag reduction: Smoother wings and complex air-friendly shapes for fuselages. There are also a lot of negatives as has been pointed out.

It’s interesting to contemplate a clean sheet design for a vintage airplane. The problem is that the old designs weren’t that bad, so improvements in an airplane like a Mooney tend to be incremental rather than monumental. It’s tough to sell a plane that is 10% better at 5x the cost of a used one when the used ones are plentiful. 

What GA really needs is some breakthrough that drastically reduces component and manufacturing cost without depending on high volume production.

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2 hours ago, PT20J said:

I think the real value of composites is in the area of drag reduction: Smoother wings and complex air-friendly shapes for fuselages. There are also a lot of negatives as has been pointed out.

It’s interesting to contemplate a clean sheet design for a vintage airplane. The problem is that the old designs weren’t that bad, so improvements in an airplane like a Mooney tend to be incremental rather than monumental. It’s tough to sell a plane that is 10% better at 5x the cost of a used one when the used ones are plentiful. 

What GA really needs is some breakthrough that drastically reduces component and manufacturing cost without depending on high volume production.

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I need to be less emotional (or less complimentary) as may be he case.  I'm out of those darn emojis again :) (not in my posts, though :) 

I'm not sure that composites are that much smoother (if at all).  I had several people at Oshkosh tell me the CJ3 wing was composite.  It isn't and never has been.  The manufacturing process is cool … but the airplanes are still aluminum.

I really, really agree with @PT20J on lowering the costs at this volume.  We should borrow from other industries.

A couple other notes on composites.  If the composite material exists in a known database, the OEM still needs to prove that they can make parts that meet those standards.  If the material is not in a database, there is a roughly $2M process of manufacturing and testing to prove the OEM can manufacture better than minimum quality to meet the proposed allowances. Fatigue is also an issue.  Yes, composites (typically) have a longer fatigue life.  Unlike aluminum, they typically don't tell you before they let go (yes, there are exceptions).  This is why all composite airframes have a set life limit.  For example, I believe that a Cirrus has to be thrown away at 14,000 hours (yes, Cirrus could extend that life with more testing).

As they would saw in Kerrville, "All y'all are awesome :) ."

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PS.  There must be a tie between airplanes and bicycles.  Thanks, Wright Brothers!

PS2.  I was beyond a @Yetti at 250 lbs., but now I ride at 175 lbs.  Aluminum frame; carbon front fork.  I can't afford more, but why anyhow.  I'm out there to get a workout.  I'm not fast either, but like the Energizer Bunny, I will, keep going and going and going.  :) 

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40 minutes ago, Blue on Top said:

I'm not sure that composites are that much smoother (if at all).  I had several people at Oshkosh tell me the CJ3 wing was composite.  It isn't and never has been.  The manufacturing process is cool … but the airplanes are still aluminum.

Point taken. I was thinking of the wing on my ‘94 J. Harmon must have put all the design effort (and weight) into the spar because the pillowing on the top of the wing is pretty obvious. But I marvel at the smoothness of a 737 wing every time I ride on one.:)

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17 minutes ago, PT20J said:

Point taken. I was thinking of the wing on my ‘94 J. Harmon must have put all the design effort (and weight) into the spar because the pillowing on the top of the wing is pretty obvious. But I marvel at the smoothness of a 737 wing every time I ride on one.:)

You should the 787!    I'm used to seeing airliners grow round rivets about two-thirds of the way down the fuselage, but the 787 is extremely smooth all the way back to the last few feet where the APU is.    I was surprised that it still has a lot of rivets or similar-looking fasteners, they're just very flush.   I don't know how they mix the composite and fastener stuff, but it's very nicely done.   The wing is the same.

I'm always amazed at how smooth many RV wings are...dang near as good as composite wings, probably near enough as makes no difference.

Every time I look out the window at the Mooney wing and see all the ripples and tank panels and round rivets and blind rivets I feel deprived.  ;) 

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Between internal structure pillowing is normal (it saves weight).

This is probably why (educated guess) the wood wing Mooneys are a little faster than the metalized ones (5-7 mph per the rumor mill).

It is easier to hide flush rivets the larger the airplane is (actually the thicker the skin is).  The Citation CJ-series has beautiful, smooth, aluminum wing skins.  So does the Citation X.  Skins on that bird are about 1/4" thick at the tip and 1/2" thick at the root.  Bondo does wonders … except for weight.

Composite structures (depending on the failure design aspects) have rivets, too.  They are (not politically correctly) called chicken fasteners.  Similar to rib stitching on fabric, they are installed to stop internal delamination/shear crack propagation/poor quality bonding growth.

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10 hours ago, PT20J said:

What GA really needs is some breakthrough that drastically reduces component and manufacturing cost without depending on high volume production.

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Only with (partly) automated production processes. That's why I posted yesterday a thought of mine that a company with enough capital to put up one or two assembly lines to manufacture composite parts with robots and without the need for autoclaves (as described in the article the link of which I posted as well) and working for different clients may be the key for solving the question you put up here.

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