Factory Closed Down?

[ArtVandelay]

[mention=11849]ArtVandelay[/mention]  As Abraham Lincoln once said, "Don't believe everything you read on the internet."  Seriously, though, there may be some parts on an airplane that can be lighter in CF, but more likely they are easier to make in CF than aluminum (like the cowling) than to be lighter than aluminum.  The vast majority of material failure modes on an airplane are in compression/buckling where CF is poor at best (it's all the resin/matrix/glue).  Aluminum has known buckling loads and fatigue characteristics; CF does not.  Please don't Google "CF fatigue".  Composites have a fatigue life just like everything else.  What they don't have is warning signs of fatigue failure.  After it fails, the matrix dust blows away.  CF is also poor with point loads, and a metallic (typically titanium, LOL) insert needs to be installed to transfer the loads through a larger surface area.
I agree with you on potential areas to remove weight (the wing spar, too), but would the weight savings be worth the cost of certification?

Cirrus spar is made of CF.

[Nick Pilotte]

I am not an aerospace engineer or anything like that but rather a grease monkey of sorts that used to repair and maintain some of the most exotic cars on the planet so I could be totally wrong here.  Between bicycling,  cars, and what I've read in some metallurgical books about titanium, machining and fabrication of titanium is difficult.  I believe titanium works well for fasteners and thermally challenged parts like exhausts.  If you look at Formula 1, they are some of the most advanced cars on the planet.  F1 teams usually have an annual budget that would make Textron blush.  They use carbon fiber because it can be worked into molds, material can be positioned or layered in different directions to alter strength and rigidity.  In fact, the tubs have a titanium halo now that protects the driver from flying debris up to and including a bouncing wheel.  If you have concerns about carbon fiber as a safety cage, it can and has been used as well.  Look up the Mercedes-McLaren SLR, McLaren P1 and others I can't remember now. The whole monocoque chassis is carbon fiber, incredibly light, and has crash boxes integrated to deflect energy in a crash.  I could see the whole Ultra cockpit being molded in CF without using a steel safety cage and still be as light or lighter.  Carbon can be used on engine mounts (a la Lamborghini or Corvette ZR1) or made of titanium that is welded like a bicycle.  That could save some front end weight which would reduce the necessary rear weights.  Landing gear can be welded in titanium, but really, a steel gear is fine too.  The weight would be low in the airframe.  I would really be interested to see what a Cirrus wing looks like with the outer skin off to see how it's made.  

 

Additional reading material if you like:

Design, Testing, Analysis, and Material Properties of Carbon Fiber Reinforced Polymers

F1 Monocoque - Survival Cell

F1 halo explained

[1980Mooney]

3 hours ago, Nick Pilotte said:

I would really be interested to see what a Cirrus wing looks like with the outer skin off to see how it's made.  

https://www.niar.wichita.edu/niarworkshops/Portals/0/Jun17_0425_PaulB.pdf

https://www.youtube.com/watch?v=-PdTNmPoY94

https://www.youtube.com/watch?v=nccXNJnOy7E

https://www.wisconsinaviation.com/aircraft-sales/cirrus-composite-repair

Wing structure and removal:

http://www.inetefb.com/Documentation/Cirrus/AMM/pdf/57-10.pdf

Damage Assessment manual showing fuselage and wing internal structure layout

http://www.inetefb.com/Documentation/Cirrus/AMM/pdf/57-10.pdf

 

Edited June 24, 2020 by 1980Mooney

[chinoguym20]

All good ideas, but don’t you think the talented people at Mooney would have considered all these potential weight saving ideas to increase useful load by now?  I’m sure they have and decided that there’s just no returns on investment.  How about thinking about achieving the same goal by increasing landing gear strength and testing that?  Surely doable and relatively easy to test and have the FAA certify?

[N201MKTurbo]

4 hours ago, Hyett6420 said:

The moto of Team GB is better never stops, so on their bikes for example, they easure every single little mini gram decrease in weight, improvement in aerodynamic efficiency etc and every year they change the bikes, kit etc to reflect these. so 17lbs in weight saving is a lot when you gradually add them all up.  Add in lighter windows, lighter cockpits parts etc and it all helps.  Do we need aluminium fuel lies or is there something else thats lighter but does the same job, do the cylinder heads need to be alu or could they be i dont know unobtanium etc.  I will guarantee one thing though, and that is that Daimlers first car was not sold at a profit.

So, who is the government agency that regulates bicycle manufacturers? And certifies every design change?

Is there a two year certification effort every time you make the slightest change?

You are talking apples and oranges.

BTW, where are all the GB GA aircraft manufacturers? Do they even make a piston single?

[Nick Pilotte]

2 minutes ago, N201MKTurbo said:

So, who is the government agency that regulates bicycle manufacturers? And certifies every design change?

Is there a two year certification effort every time you make the slightest change?

You are talking apples and oranges.

BTW, where are all the GB GA aircraft manufacturers? Do they even make a piston single?

Unsurprisingly to me based off the rest of the regulations I have seen from there, and that is no knock on them either......It looks like British bicycles fall under a few regulatory areas.  

GPSR 2005 was adopted by the Brits, though it's an EU reg.

Then it also looks like there is BS 6102-1 by British Standards Institution.  I tried to link it but everywhere I looked, I had to purchase a copy of the regulation for $$$$!!!!!  

[aviatoreb]

1 hour ago, N201MKTurbo said:

So, who is the government agency that regulates bicycle manufacturers? And certifies every design change?

Is there a two year certification effort every time you make the slightest change?

You are talking apples and oranges.

BTW, where are all the GB GA aircraft manufacturers? Do they even make a piston single?

I disagree - this isn't apples and oranges. In the world of is it plausible engineering it is very much a comparable concept since many parts in our Mooney's are made with the same materials with similar procedures as bicycles.  The chromoly frame is cut and welded in the same general way as a classic chromoly bike frame.  The landing gear parts are also something any self respecting custom bicycle frame builder could copy easily.

Certification of procedures and methods is clearly the big difference, but if we just throw up our hands and say you can't do or think of anything different because certification is expensive, well then we end just up selling a 50 year old design that never changes and we go bankrupt.  It is hard, and it is expensive and it takes money but it is at least plausible.

Edited June 24, 2020 by aviatoreb

[aviatoreb]

5 hours ago, 1980Mooney said:

https://www.niar.wichita.edu/niarworkshops/Portals/0/Jun17_0425_PaulB.pdf

https://www.youtube.com/watch?v=-PdTNmPoY94

https://www.youtube.com/watch?v=nccXNJnOy7E

https://www.wisconsinaviation.com/aircraft-sales/cirrus-composite-repair

Wing structure and removal:

http://www.inetefb.com/Documentation/Cirrus/AMM/pdf/57-10.pdf

Damage Assessment manual showing fuselage and wing internal structure layout

http://www.inetefb.com/Documentation/Cirrus/AMM/pdf/57-10.pdf

 

Those are very very interesting.

Question - is it plausible to redo just the skins - I am asking engineering terms - not the obvious bugaboo of certification?  For build time saving reasons that is.  Could the Mooney be skinned in carbon fiber bonded as above?  Does carbon bond to metal framing and and metal spars?  It looks like it would save time, parts, and also result in a smoother body.  As a transition to other methods for rethinking the build procedures.

[Blue on Top]

9 hours ago, ArtVandelay said:

Cirrus spar is made of CF.

@ArtVandelay  Yes, the spar of a Cirrus is carbon fiber … the only part.  Well, except the paint scheme.  There would be several issues trying to put an aluminum spar into a composite skin and ribs.

BTW: The flight controls and flaps are aluminum … for the reasons I have stated previously.  Cirrus is heavy; and they know it.  Chute sells … to that type of pilot.

[N201MKTurbo]

16 minutes ago, Nick Pilotte said:

Unsurprisingly to me based off the rest of the regulations I have seen from there, and that is no knock on them either......It looks like British bicycles fall under a few regulatory areas.  

GPSR 2005 was adopted by the Brits, though it's an EU reg.

Then it also looks like there is BS 6102-1 by British Standards Institution.  I tried to link it but everywhere I looked, I had to purchase a copy of the regulation for $$$$!!!!!  

There is a big difference between a set of regulations that you must follow and an agency that requires your design and production to be certified before you can even start producing the product.

[Nick Pilotte]

5 minutes ago, Blue on Top said:

@ArtVandelay  Yes, the spar of a Cirrus is carbon fiber … the only part.  Well, except the paint scheme.  There would be several issues trying to put an aluminum spar into a composite skin and ribs.

BTW: The flight controls and flaps are aluminum … for the reasons I have stated previously.  Cirrus is heavy; and they know it.  Chute sells … to that type of pilot.

Would there be similar implications of a bonded CF skin to aluminum spar and ribs?  

[Shadrach]

11 hours ago, aviatoreb said:

Could be only 14lbs.  If that's all then definitely not worth it.

How much does a bare bones Mooney weight, all in, no avionics, no rubber, no engine, no interior - just the frame and skins metal bits?

My WAG is around 850ish.

[Blue on Top]

2 minutes ago, Nick Pilotte said:

Would there be similar implications of a bonded CF skin to aluminum spar and ribs?

@Nick Pilotte  In a single word, "Yes."   It can be done, though.  The CTE (coefficient of thermal expansion) between the composite material and the metallic material has to be accounted for.  Also, there will need to be some chicken fasteners installed to stop crack propagation when/if the bond line fails (yes, it's in the regulations).

Another consideration is damage tolerance.  The minimum layup for composites is typically 2-core-2, and aluminum is lighter than this … unless the skin is load carrying on the inboard portions of wing.  Why 2-core-2?  The core is to add stiffness, but … can one damage the inside without a noticeable mark on the outside? (hail, dropped tool, etc.)

[aviatoreb]

39 minutes ago, Blue on Top said:

@Nick Pilotte  In a single word, "Yes."   It can be done, though.  The CTE (coefficient of thermal expansion) between the composite material and the metallic material has to be accounted for.  Also, there will need to be some chicken fasteners installed to stop crack propagation when/if the bond line fails (yes, it's in the regulations).

Another consideration is damage tolerance.  The minimum layup for composites is typically 2-core-2, and aluminum is lighter than this … unless the skin is load carrying on the inboard portions of wing.  Why 2-core-2?  The core is to add stiffness, but … can one damage the inside without a noticeable mark on the outside? (hail, dropped tool, etc.)

So you know about this concept and I am just day dreaming about this concept.  So let me ask the bottom line - is it reasonable to think of bonding a carbon sheet over a metal frame say on the wing?  Is it a time saver in build?  Is it structurally sound?  Seems like it would at least be faster to build, fewer parts and smoother in the end.

Or...could that be just as well be a bond on procedure using one very big pre-shaped piece of metal/aluminum skin?  Well not one, but anyway very large pieces bigger than usually used today.

[cliffy]

Does anyone even remember the long process when they went to two doors and a composite shell (non-structural) fairing around the cabin instead of aluminum? How long did that effort take to get certified? I think it even caught them off guard as to how long it took and what the Feds required (JMO). Now we're talking redoing ALL the primary load carrying structures in composite? Primary load path, secondary load path, crack propagation mitigation, etc etc. NOT just fairings here. Not just a few 4130 steel tubes being moved around. 

You'd have as much in certification costs as you'd have in a completely new design. The killer is always going to be certification costs, ESPECIALLY NOW with the 737 MAX fiasco by the FAA and Boeing. From now on the FAA is going to dot every "i" and cross every "t" twice before they sign off anything.

If you want to look at the challenges and costs of certification just look to the AV-30 or the TT autopilot! and they ain't a full airframe structure!

And what is the end game?

Lighter weight ? Ain't gonna happen

Better aerodynamics? MEH! Not that much gain for the effort. You only have so much HP to play with. Its either HP or drag to play with for speed. Then you still have to slow down to TO and land for reasonable distances. There ain't no magic formula or process here.  Its all physics. Its all a give and take process.  Wishing won't make it so. Think about it- 200 HP Cirrus' are M20J speeds. Both 200 HP no magic. 

The fastest single engine in production (Mooney)? 10% either way doesn't account for the disparity in numbers down the production line.

Customer Visual Appeal?  If this then a new design might be better in the long run. 

You can sell sand in the desert with the right marketing! You can't sell water in the desert if no one knows you're there. 

Edited June 24, 2020 by cliffy
added text

[aviatoreb]

I sometimes (well often) get junk mail and today's junk mail included this video from "Lightspeed" a Ti bike building company in Tennessee.  Which is interesting to see the craftsmen work.

 

[cliffy]

23 hours ago, Trailboss said:

One of my first internships was at a small CNC shop outside of Wichita that did piece work for Boeing.  100% Aluminum machined parts.  They received a contract to make 1,000 widgets out of Ti and thought, sure...we can do that.  First block loaded on the table was about 3"x4"x6" and everyone marveled at how light it was!  Well, push the green button with speeds and feeds set for Al and...  the whole machine nearly vibrated off the anchor bolts.  Titanium is cool...but man is it brittle and HARD.

when the SR71 was built it brought in an entirely new process for machining and welding just for Ti. It was a very big deal as it was the first heavy use of Ti in aviation. It was a hard learning process. 

[afward]

46 minutes ago, cliffy said:

when the SR71 was built it brought in an entirely new process for machining and welding just for Ti. It was a very big deal as it was the first heavy use of Ti in aviation. It was a hard learning process. 

I forget where I read it, but the initial parts made for the A-12 program were unusable due to cadmium (causing cracks) and chlorine (causing corrosion) poisoning.  Turns out the factory's tooling was cadmium hardened and they were using municipal water to rinse the parts.  New non-cadmium tooling and use of distilled water allowed them to make usable parts, though not before a rather substantial quantity of Ti had been "wasted" (er, well, needed to be re-smelted; not something the U.S. could do at the time, if I recall correctly).

[exM20K]

17 hours ago, Blue on Top said:

@ArtVandelay  As Abraham Lincoln once said, "Don't believe everything you read on the internet."  Seriously, though, there may be some parts on an airplane that can be lighter in CF, but more likely they are easier to make in CF than aluminum (like the cowling) than to be lighter than aluminum.  The vast majority of material failure modes on an airplane are in compression/buckling where CF is poor at best (it's all the resin/matrix/glue).  Aluminum has known buckling loads and fatigue characteristics; CF does not.  Please don't Google "CF fatigue".  Composites have a fatigue life just like everything else.  What they don't have is warning signs of fatigue failure.  After it fails, the matrix dust blows away.  CF is also poor with point loads, and a metallic (typically titanium, LOL) insert needs to be installed to transfer the loads through a larger surface area.

I agree with you on potential areas to remove weight (the wing spar, too), but would the weight savings be worth the cost of certification?

Example: DA40 vs Archer... DA40 is approx 200# heavier for an roughly equivalent aircraft.

-dan

[Nick Pilotte]

I guess I should clarify the reason for my post.  Titanium is not cheap to work with in manufacturing. CF and composites are ways to reduce production expenses, at the cost of redesign and recertification expenses (both time and financial). This is where identifying the design that will sell for a determined price.  The likelihood a fresh sheet design will bring an immediate profit to the company is a pipe dream.  But if a team could find the correct market price and product to sell then it could rebuild the company.  

[bonal]

Ok so I'm no expert as some have pointed out having said that please bare with me as I'm unaware of how max gross weight is determined.  I keep seeing this stall speed of 59 knots being referenced is this a requirement for certified airplanes to be no higher than this number.  And if so is it the main specification that sets the max gross for any single engine type.  If so and since the number one reason people site for Mooney design issues is insufficient useful load.  Would it be possible to re engineer the flaps which most agree are somewhat ineffective and perhaps go with a fowler design which if I'm not mistaken adds square footage to the wing area.  If my premise is correct about stall speed driving max weight seems the easiest way to improve GW would be to lower stall speed.  If my premise is flawed then please forget I brought it up other than to inform me how max gross is determined.

[Blue on Top]

5 minutes ago, bonal said:

I keep seeing this stall speed of 59 knots being referenced is this a requirement for certified airplanes to be no higher than this number.  And if so is it the main specification that sets the max gross for any single engine type.  If so and since the number one reason people site for Mooney design issues is insufficient useful load.  Would it be possible to re engineer the flaps which most agree are somewhat ineffective and perhaps go with a fowler design which if I'm not mistaken adds square footage to the wing area.  If my premise is correct about stall speed driving max weight seems the easiest way to improve GW would be to lower stall speed.  If my premise is flawed then please forget I brought it up other than to inform me how max gross is determined.

@bonal  OMG!  Perfect lead in!  The magic number with stall speed is actually 61 knots.  The certification basis for all M20s is CAR 3 (various amendment levels, though), which states the airplane must stall at or below 61 knots in the landing configuration.  But, if it goes above 61 knots, Mooney could go to a newer certification regulation (Part 23) which allows the stall speed to go above 61 knots.  The drawback to this is the seats would then need to be brought up to the current 26G requirement … and that is a HUGE deal.

Your flap idea is actually a good one.  If done correctly, ALL structural loading and testing with flaps would need to be re-addressed.

Your premise is not flawed at all.

Gross weight is set by many variables: structures, aerodynamics, performance, etc.

[aviatoreb]

7 minutes ago, Blue on Top said:

@bonal  OMG!  Perfect lead in!  The magic number with stall speed is actually 61 knots.  The certification basis for all M20s is CAR 3 (various amendment levels, though), which states the airplane must stall at or below 61 knots in the landing configuration.  But, if it goes above 61 knots, Mooney could go to a newer certification regulation (Part 23) which allows the stall speed to go above 61 knots.  The drawback to this is the seats would then need to be brought up to the current 26G requirement … and that is a HUGE deal.

Your flap idea is actually a good one.  If done correctly, ALL structural loading and testing with flaps would need to be re-addressed.

Your premise is not flawed at all.

Gross weight is set by many variables: structures, aerodynamics, performance, etc.

I remarked the same thing earlier in the thread and described that VGs must be the cheapest easiest way to lower stall speed.  I installed VGs on my plane and it did lower the stall speed several knots.

But I thought it was the weight bearing capacity of our current gear that is the problem, and that would take a new gear design.

[Blue on Top]

5 hours ago, aviatoreb said:

So let me ask the bottom line - is it reasonable to think of bonding a carbon sheet over a metal frame say on the wing?  Is it a time saver in build?  Is it structurally sound?  Seems like it would at least be faster to build, fewer parts and smoother in the end.

Or...could that be just as well be a bond on procedure using one very big pre-shaped piece of metal/aluminum skin?  Well not one, but anyway very large pieces bigger than usually used today.

@aviatoreb This is just my opinion.  Bonding dissimilar materials together that are this large is not a good idea.  Bonding aluminum to aluminum is a good idea.  Bonding CF to CF is okay, too.  CF to CF is just heavy and tolerances are critical (bond line thickness like resin content is a large weight driver.  CF parts vary in weight +/- 7%.  On a plus note for composites is the more of the structure that is co-cured, the lighter is becomes.  The drawback to that is one simple mistake causes a much higher dollar part to be scrapped ... ask Boeing about the $BB they spent developing the 787 processes.

As others have mentioned the bottom line, the wood wing by rumor is 5-6 mph faster than the aluminum wing.  This is most likely due to the plywood maintaining shape better than the thin aluminum.  The wood wing was fabric covered. 

[PT20J]

I keep hearing that Mooney flaps are ineffective. Flaps are used to lower stall speed which allows shorter runways to be used. If you compare Vso and Vs1 calibrated stall speeds from various GA singles (I’ve done that in other threads) you find that Mooney has one of the largest spreads. 

Perhaps we are more used to Cessnas and Pipers that have flaps that don’t decrease stall speed much but do create a lot more drag making steeper approaches easier. Maybe this makes them seem more effective. 

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