A full composite Mooney. Possible or not?

[Cargil48]

@Blue on Top replied to me in another topic it would not be feasible to build a vintage Mooney model (I suggested the E) in full composite construction because of the higher weight and costs. Is it really so? In many places I read composite materials are stiffer and lighter than metal. Apart from being much cheaper to build an airplane out of it because of the enormous reduction in parts to be joined until de aircraft is finished.

An interesting article I stumbled upon says:

"The last few decades have seen a steady rise in the amount of ‘composite’ materials used in the airframe of aircraft. These have added strength but lowered the overall weight of the aircraft. The use of composites in one new aircraft has generated a weight saving of 20% over traditional aluminium alloys."

If so, would it theroretically be feasible (and payable...) to make a Mooney like a Cirrus SR22, fully in composite materials?

Source for my quote: https://aviationbenefits.org/case-studies/new-materials-and-structural-weight-saving/

PS: This article from Boeing is also very interesting: http://www.boeing.com/commercial/aeromagazine/articles/qtr_4_06/article_04_2.html

Edited December 16, 2019 by Cargil48
Adding new link

[Little Runaway]

There are a lot of misconceptions out there regarding the use of composite materials in aircraft. Many people immediately think of carbon fiber but composite aircraft are also designed from fiberglass, Kevlar, and other plastic materials.

Carbon fiber can be used to create very complex structures with low parts counts. It can also be stiff and lightweight. Notice the use of the word "can" above. Poor designs/layups end up being heavier/weaker than an aluminum alloy part.

One of the really cool things about working with it is that different fiber weaves/strand orientations can be used to precisely control strength and stiffness in specific orientations with respect to the part.

Carbon structures aren't the magic bullet, however. Working with composites generates hazardous fumes and dust, requires complex tooling, molds, autoclave, etc. Oh yeah, it's really expensive too.

Carbon Fiber is also reactive so there are special considerations when bonding/mating it with other materials. There are special HIRF and Lightning considerations as well.

One of the biggest challenges with small aircraft like Cirrus or Diamond is structural repair. It often requires an engineering analysis authorized by the factory. I purchased a salvage DA-20 several years ago that had a relatively simple nose wheel collapse and the factory refused to approve a repair.

All that being said, Cirrus, Diamond, and others have successfully produced many small composite aircraft without rivets and there are many happy owners.

So to your question about making a Mooney exclusively from composite materials--I think you would find that the aircraft wouldn't look just like the Mooney. Much of what makes a Mooney look like a Mooney is because of how it was constructed. Metal fuselage frame with unstressed skin bolted to a semi-monocoque empennage with an all-moving tail. Lots of parts! You can see where the OML changes on a Mooney in these areas. It would probably be more practical to do what Cirrus does--just join two fuselage halves together, which would likely result in a more blended look, i.e., Cirrus.

My 2 cents. Hopefully this provides some additional insight.

Aaron

[Yetti]

I think if you look, the FAA considers Wood and cloth as "composite"   I don't think you want spun glass and expoxy shaped like a Mooney.   One of the reasons I fly a Mooney is because of the steel roll cage that holds the aluminum panels on.   Should I have a bad day and bend metal the roll cage is going to protect me.  Can some of the control tubes be replaced with Carbon to reduce weight?  Maybe.  Probably.   The best description of Mooney I have heard is a flying tube structure bolted to P 51 wing with sheets of aluminum to keep the wind off the passengers.

[aviatoreb]

23 minutes ago, Yetti said:

I think if you look, the FAA considers Wood and cloth as "composite"   I don't think you want spun glass and expoxy shaped like a Mooney.   One of the reasons I fly a Mooney is because of the steel roll cage that holds the aluminum panels on.   Should I have a bad day and bend metal the roll cage is going to protect me.  Can some of the control tubes be replaced with Carbon to reduce weight?  Maybe.  Probably.   The best description of Mooney I have heard is a flying tube structure bolted to P 51 wing with sheets of aluminum to keep the wind off the passengers.

I like the idea of a carbon fiber wing - but shaped same as it is now but smoother / bolted on to an otherwise traditionally built Mooney.

Edited December 16, 2019 by aviatoreb

[MooneyMitch]

33 minutes ago, Yetti said:

I think if you look, the FAA considers Wood and cloth as "composite"   I don't think you want spun glass and expoxy shaped like a Mooney.   One of the reasons I fly a Mooney is because of the steel roll cage that holds the aluminum panels on.   Should I have a bad day and bend metal the roll cage is going to protect me.  Can some of the control tubes be replaced with Carbon to reduce weight?  Maybe.  Probably.   The best description of Mooney I have heard is a flying tube structure bolted to P 51 wing with sheets of aluminum to keep the wind off the passengers.

Off topic...... but, please don’t think the cabin steel tubing is a roll cage.  My opinion..... a “roll cage” implies a strong structure designed to help protect a person in a crash, such as in a race car.

Thinking the Mooney tubing is a roll cage could possibly instill a false sense of security ..........Wouldn’t want that for ANYONE ! 

The Mooney tubing is not, and was never designed to be a roll cage.  

It has been beneficial in some instances.  

[Releew]

I think If Mooney would design a Composite Aircraft (J Model) wrapped around a tube steel cage they would have one hell of an offering.  I also believe it would bring the labor hours down, allowing for a better price point in category.  Obviously, they need to KEEP what works, i.e. the profile, the articulating tail...etc.   Throw a BRS in the offering as an option and just maybe they could compete with the outfit up north!  Just think of the speed they could get with a smooth skin and Mooney aerodynamics.  Get that price under 500K with a 220 Knot cruise and that would be an offering!!!

I know......Dreaming!

Rick

[Yetti]

16 minutes ago, MooneyMitch said:

Off topic...... but, please don’t think the cabin steel tubing is a roll cage.  My opinion..... a “roll cage” implies a strong structure designed to help protect a person in a crash, such as in a race car.

Thinking the Mooney tubing is a roll cage could possibly instill a false sense of security ..........Wouldn’t want that for ANYONE ! 

The Mooney tubing is not, and was never designed to be a roll cage.  

It has been beneficial in some instances.  

Al Mooney disagrees with your assessment

http://www.mooney.airmoon.co.za/the-al-mooney-legacy/

Looks like you have already weighed in on this

http://www.pilotspost.com/arn0001726

An integrated, composite skin now wraps our legendarily strong tubular cabin roll cage. This reinforces the Ultra's sleek aerodynamic lines, slices through the air and further silences the interior during flight.

 

so the question can still remain did Al design the 4130 cromoly tubular structure to protect the occupants if so then we could agree "roll cage" should apply.

 

[mstephenson51]

I built a composite (carbon fiber) wing for my senior design class.  Went well!  did a lot with fully carbon race cars as well, so I have seen a bit about the design and fab of these kinds of things.

I personally love carbon composites, esp for planes where cost isn't really an object.  Metal just cost sooooo much less.  Anyway, carbon/glass/kevlar composite have the obvious plus of being able to easily handle 250,000 psi tensile strength before yielding where 6061-T6 is like 40,000.  Down side is that in COMPRESSION, they are way less.  Also, one SERIOUSLY bad part is trying to do things like a bolt on wing.  Have to have some kind of metal or phenolic bolting plate bonded in, and the heat cycles of a plane can shred that bond.  Super hard to get the molded in mounting points to stay.  By way of ref:  we had the engine mounting studs of an indycar engine pull out of the carbon chassis because they were not properly bonded.

Sorry to babble on and on....   Long story short, my carbon wing was small ish and about the size of a 1 seat plane.  but handled 2600 pounds of load before yielding while the one side wing was only 8 pounds.

[MooneyMitch]

30 minutes ago, Yetti said:

Al Mooney disagrees with your assessment

http://www.mooney.airmoon.co.za/the-al-mooney-legacy/

Looks like you have already weighed in on this

http://www.pilotspost.com/arn0001726

An integrated, composite skin now wraps our legendarily strong tubular cabin roll cage. This reinforces the Ultra's sleek aerodynamic lines, slices through the air and further silences the interior during flight.

 

so the question can still remain did Al design the 4130 cromoly tubular structure to protect the occupants if so then we could agree "roll cage" should apply.

 

No !

The part your quoting is marketing BS, again.

The people writing that stuff have no historical information to support their false information.

[MooneyMitch]

“Al Mooney disagrees with your assessment“

Correct....... it was Copeland that came up with that BS!  He was spouting that stuff at the 2008 AirVenture Mooney tent .

Again, false verbiage written by marketing.

 

[kmyfm20s]

I look at the steel cage in a Mooney more as an energy absorption device than a roll cage. It’s better than other aluminum aircraft but not like a race car. Race cars dissipate the energy by actually rolling with planes that usually not the case.

[DanM20C]

Here are Al's actual words from an article he wrote in the Sep, 1952 issue of Flight Magazine.  Thanks to Bob Kromer for handing out copies at Mooney Summit VII.

"The cabin fuselage section is of welded steel tube structure uniquely designed to permit unobstructed windows, doors and cabin interior.  This design results in a smaller frontal area for a given interior size.  It also provides an effective impact-resisting "island structure" around the occupants."  - Al Mooney

So Al never refers to it as a "roll cage" nor did anyone from Nascar help design it.  it's crash worthiness wasn't the main design consideration but it certainly has developed a deserving reputation as a tough air-frame.   My self as well as a few of my friends are still here after Mooney crashes, and the physical evidence of the airplane points to the "Island structure" playing a major part in the outcomes.  

I think Al's statement above has a bit of marketing talk embedded too.   I don't disagree with anything he said, but I think the real reason he built the M20 the way he did was lack of deep pockets.  He didn't have the capitol to tool up for an all aluminum airplane.  So he designed and build the most aerodynamically modern airplane he could with traditional techniques and materials.  When Al was forced from the company the M20 still was mostly wood. Over the next few years the wood tail was replaced with aluminum, then the wings, etc..  The airplane kept getting improvements but the steel cage stayed.  I bet if someone with deep pockets(like Beech or Piper) hired Al before the M20 and said "design us a 4 place airplane", it wouldn't have had the steel cage.  But, I'm glad they didn't.

Cheers,

Dan

[MooneyMitch]

1 minute ago, DanM20C said:

Here are Al's actual words from an article he wrote in the Sep, 1952 issue of Flight Magazine.  Thanks to Bob Kromer for handing out copies at Mooney Summit VII.

"The cabin fuselage section is of welded steel tube structure uniquely designed to permit unobstructed windows, doors and cabin interior.  This design results in a smaller frontal area for a given interior size.  It also provides an effective impact-resisting "island structure" around the occupants."  - Al Mooney

So Al never refers to it as a "roll cage" nor did anyone from Nascar help design it.  it's crash worthiness wasn't the main design consideration but it certainly has developed a deserving reputation as a tough air-frame.   My self as well as a few of my friends are still here after Mooney crashes, and the physical evidence of the airplane points to the "Island structure" playing a major part in the outcomes.  

I think Al's statement above has a bit of marketing talk embedded too.   I don't disagree with anything he said, but I think the real reason he built the M20 the way he did was lack of deep pockets.  He didn't have the capitol to tool up for an all aluminum airplane.  So he designed and build the most aerodynamically modern airplane he could with traditional techniques and materials.  When Al was forced from the company the M20 still was mostly wood. Over the next few years the wood tail was replaced with aluminum, then the wings, etc..  The airplane kept getting improvements but the steel cage stayed.  I bet if someone with deep pockets(like Beech or Piper) hired Al before the M20 and said "design us a 4 place airplane", it wouldn't have had the steel cage.  But, I'm glad they didn't.

Cheers,

Dan

Excellent!  

[jetdriven]

A steel truss covered by fabric (or aluminum) like this is prewar technology. The piper cub was built this way. So was the Meyers 200. Piper PA23. Not bad. Just obsolete design. But it is pretty tough. 

[PT20J]

2 hours ago, MooneyMitch said:

Off topic...... but, please don’t think the cabin steel tubing is a roll cage.  My opinion..... a “roll cage” implies a strong structure designed to help protect a person in a crash, such as in a race car.

Thinking the Mooney tubing is a roll cage could possibly instill a false sense of security ..........Wouldn’t want that for ANYONE ! 

The Mooney tubing is not, and was never designed to be a roll cage.  

It has been beneficial in some instances.  

According to the attached article (courtesy of Bob Kromer), Al Mooney did intend the tubular structure to improve crashworthiness.

Edit: Didn't notice Dan's post before I wrote this. Anyway, the complete article has lots of other interesting tidbits.

 

Skip

Al Mooney article 1952.pdf

Edited December 16, 2019 by PT20J

[Blue on Top]

@Cargil48 Not only is this a great thread.  There have also been some great posts, too.

My answer to the thread topic, "A Full Composite Mooney.  Possible or not?"  Yes, it is possible.  In my opinion it will be heavier and a lot more expensive.  Full disclosure, I was the Mooney Chief Engineer on the all carbon fiber M10.  We followed that rabbit down the hole.  Here are my reasons, many of which have been mentioned previously.

•  Composites are best in pure tension (tensile strength, pulling a piece apart).  Most small airplane structure is designed around buckling and minimum thickness materials.  For example, nothing will be lighter than aluminum for control surfaces (for just structure).  Why? 2 core 2 is the thinnest/lightest composite layup for a certificated airplane.  Why?  Ths is the minimum buildup that will pass strength, buckling and damage tolerance (hail, hit by a wrench, etc.).  To explain that a little more, if one hits the outer surface with something, and it damages the inner surface or core without showing damage on the outside (inspect-able area), it is bad.   Aluminum is lighter ... look at a Cirrus (it's aluminum)
• The highest loaded area of an airplane is the upper spar cap.  It is in compression.
• Carbon (much less for fiberglass) needs to have a copper mesh (something metallic) to disperse HIRF and lightning to the exit (typically somewhere off the empennage).  IOW, every part of the airplane has to be electrically bonded to every other part of the airplane.  In the case of a flight control, the now heavier surface also needs a much heavier counter balance (normally 3 or 4 times the weight delta of the surface - the counter balance has a smaller arm).  Heavier balance weights are bad as they torsionally twist the flight control ... and bad things happen ... ask the Beech 35 people.
• Changes to tooling (especially prototype tools) are very expensive.  Production composite tooling cost is very quantity dependent.
• Depending on many, many factors, labor costs can be much higher or lower.  I got dinged for how many hours the shell takes on the M20 … not my design, though .  Yes, no holes to drill/punch, debur or rivet, but I also don't have to build my material (it comes on a roll).
• It is also dependent on how the tooling is used, how many tools have to be made to meet quantities, if the tools are used only to make parts or if they are also used in assembly, etc.

Again, MS is great.  I love the discussions.  I like the M20 construction, but it's not the lightest.  The M20 wing is too heavy (and has too much margin).  Remember it was designed by Ralph Harmon that had not too long before had serious problems with the strength of the Bonanza wing and tails.

PS. The 787 is not composite for light weight or initial cost; it is composite because it doesn't corrode.

PS2.  I love, love, love the Al Mooney design article; it is outstanding.  Although back then smaller frontal area was associated with lower drag, that's not necessarily true today with current CFD.   

[KSMooniac]

Composites can be lighter, or heavier. Or much heavier. It depends on the plane, and more specifically which part you want to study.

In the commercial transports, composite tech bought it's way in to the last generation of products (sort of)... But only for the wide body planes so far. When the 787 was being hatched, many of the studies showed a plastic 737-size airplane would be heavier and more expensive . So the latest 737 and A320 are still aluminum. It will be very interesting to see what the next gen will be in that end of the market...

Cirrus and Lancair got modern Pt 23 planes certified with composites, but they sure aren't lighter due to cert requirements for redundancy. They're stout, though. (But not very energy-absorbing like a metal plane, be and especially a steel tube structure like ours!)

Part of the issue is that while carbon fiber is stronger than steel in terms of specific strength (ie per weight), it has negative characteristics in terms of impact resistance as one example. By the time you make it robust enough to resist some hail, normal handling, birds, etc it can end up heavier than a comparable aluminum structure. Exhibit A might be the aluminum ailerons in a Cirrus! It's especially bad if you have to bolt it together... It requires significant pad-ups to get good bearing strength.

The modern cert standards also drive more weight into the airframe, especially seats and floors. That means if you tried to certify an equivalent M20 today with the same design and materials, it will end up a lot heavier. That is a big reason the King Air has kept soldiering on after 50 years... Nobody could build one better today from a clean sheet.

We might see some technology leaps that enable lighter airframes with composites, or perhaps radically cheaper or quicker to fabricate, but with current approved materials and processes, aluminum can still be the optimal choice in many cases. No doubt that a fully molded airframe can offer huge aero advantages in terms of holding the proper profile and deleting drag-producing features, but some of that benefit is offset by weight and cost. The tech is evolving, though, and we will see some cool new products in the next 10-20 years. Hopefully there will still be a GA market than can take advantage of it.

Sent from my LG-US996 using Tapatalk

[PT20J]

13 minutes ago, Blue on Top said:

Although back then smaller frontal area was associated with lower drag, that's not necessarily true today with current CFD.   

I think he might have meant smaller wetted area. Since he was clearly taking aim at the Bonanza, it’s interesting to compare equivalent flat plate areas (courtesy of David Lednicer):

Bonanza: 3.50 ft^2
Mooney: 2.81 ft^2

Skip

[Cargil48]

7 hours ago, DanM20C said:

Here are Al's actual words from an article he wrote in the Sep, 1952 issue of Flight Magazine.  Thanks to Bob Kromer for handing out copies at Mooney Summit VII.

"The cabin fuselage section is of welded steel tube structure uniquely designed to permit unobstructed windows, doors and cabin interior.  This design results in a smaller frontal area for a given interior size.  It also provides an effective impact-resisting "island structure" around the occupants."  - Al Mooney

(...)

Cheers,

Dan

That is what in Formula One is called the "surviving cell". And good old Al Mooney may hopefully send me a wireless Wi-Fi linked message from Heaven's central message services ( )to my email, pease, and tell me difference of "an effective impact-resisting "island structure" around the occupants." and what we nowadays call "rollcage"... Maybe his definition is more accurate, but the meaning - IMHO - is the same...

Edited December 16, 2019 by Cargil48

[Cargil48]

Friends, I must admit that I'm overwhelmed with the replies you've given to the thread I started. This is what I adore in forae (like @Blue on Top...): To debate ideas and learn from the answers. A big Thank you to all of you!

Carlos

[Guest]

Greatly lighter composite airframes are not a reality.  Most SR22’s weigh almost the same as  Ovations and Acclaims.  DA40’s weigh more than Archers and 172’s.

Clarence

[GeeBee]

The problem with composites is they are not very scalable on the down side. Beech found that out with the Starship. You can do it, and Cirrus does it every day but the weight savings are not as dramatic as on larger aircraft. Then even if you do it, you have to amortize the production cost increases which requires a lot of units.

 

[Jerry 5TJ]

6 hours ago, Blue on Top said:

The M20 wing is too heavy (and has too much margin).

I’d long suspected that. Thanks for the verification.   
When overstressed an M20 seems never to break a wing. Something else yields first. 

[Yetti]

9 hours ago, MooneyMitch said:

“Al Mooney disagrees with your assessment“

Correct....... it was Copeland that came up with that BS!  He was spouting that stuff at the 2008 AirVenture Mooney tent .

Again, false verbiage written by marketing.

 

Ok let's agree that "roll cage" is not a great term to apply to an airplane.   unless you can rip the wings off before crashing, there won't be alot of rolling.   Impact zones and crumple zones.   I guess the definition we should be searching for is.  Did Al put extra tubing in the frame specifically for occupant protection or are the tubes just there to hold the wing on and other things?

 

[Yetti]

10 hours ago, mstephenson51 said:

I built a composite (carbon fiber) wing for my senior design class.  Went well!  did a lot with fully carbon race cars as well, so I have seen a bit about the design and fab of these kinds of things.

I personally love carbon composites, esp for planes where cost isn't really an object.  Metal just cost sooooo much less.  Anyway, carbon/glass/kevlar composite have the obvious plus of being able to easily handle 250,000 psi tensile strength before yielding where 6061-T6 is like 40,000.  Down side is that in COMPRESSION, they are way less.  Also, one SERIOUSLY bad part is trying to do things like a bolt on wing.  Have to have some kind of metal or phenolic bolting plate bonded in, and the heat cycles of a plane can shred that bond.  Super hard to get the molded in mounting points to stay.  By way of ref:  we had the engine mounting studs of an indycar engine pull out of the carbon chassis because they were not properly bonded.

Sorry to babble on and on....   Long story short, my carbon wing was small ish and about the size of a 1 seat plane.  but handled 2600 pounds of load before yielding while the one side wing was only 8 pounds.

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.