Brand new... Old Yank metal -v- new plastic fantastic.

[eltonioni]

Times seem to be a changing so would anyone buy a brand new aircraft based on a 40 or 50 year old design from Cessna / Piper / Beech / Mooney /etc rather than one of the newer designs?

[Rod1]

“Times seem to be a changing so would anyone buy a brand new aircraft based on a 40 or 50 year old design from Cessna / Piper / Beech / Mooney /etc rather than one of the newer designs?”

This is a subject, which comes up on a regular basis, so you may want to do a search. Personally, no I would not touch a 50 year old design, particularly if it had a 60 + year old engine to go with it.

You then get into the IFR V VFR debate. I sold my AA5B and built a Plastic fantastic, which is VFR day only but does 138kn on 15 lph of mogas and will lift two 90kg people with 4 hours plus fuel. It gets me round Europe and I have more fun, but others will say you have to go with an IFR 4+ seats etc. It depends on your mission profile. I would rather have new Cirrus than a new 172, but I would rather have my MCR01 over both.

Rod1

[Flintstone]

mission profile

Ooooh, sexy pilot talk. I'm positively moist :E

[A and C]

When it comes to damage repair the more I have to do with Plastic the more I like metal!

Plastic is very unforgiving and I can't help thinking that we are about to have a spate of problems resulting from a lack of correct inspection and repair of plastic structurers, some of these resulting from poor instructions from American manufactures who's repair knowlage is light years behind the European industry.

[wsmempson]

Of course, if GA aircraft had a similar lifespan/depreciation curve to cars, the would be no contest; we would all move on to the new generation of tourers, such as Cirrus, Diamond, Columbia et al.

As to who it is who buys NEW Pipers, Cessna's or Socata's (perhaps this is a bad example, as I don't know if new Socata's are still produced - IO540?), it is probably either flying schools or rental organisations adding to an existing fleet of similar a/c, or cynical end users who distrust the new technology (sometimes with good reason) who don't feel like doing long term product development for the manufacturers.

The more usual choice for sole operaters like me is that of a 20-30 year old machine, but one which has been refurbished top to bottom. If you factor in new paint, avionics, interior and engine, all you are left with is the airframe that dates back 20/30 years, the other componants being the new section of "the woodmans favorite axe".

So, £50-80,000 for a spanking refurbed bit of well understood old technology - with depreciation following a Sine wave (about a median line dictated by maintenance) or £250-300,000 with depreciation like an anvil out of a window and new technology?:hmm:

[hobbit1983]

So, £50-80,000 for a spanking refurbed bit of well understood old technology - with depreciation following a Sine wave (about a median line dictated by maintenance) or £250-300,000 with depreciation like an anvil out of a window and new technology?

But what about the benefits of said new technology - eg. BRS parachutes, G1000 situation awareness & ease of use, FADECs, and in the case of the new diesel engines ala Diamond etc, siginificantly improved fuel efficiency - presumably the DA-42 is selling well IIRC to flying schools globally (Europe, US, China) because of these points?

[eltonioni]

That new tech can be fitted to an old airframe.

[wsmempson]

Fuel efficiency is certainly becoming the elephant in the living room and is a valid point. I, from my limited experience, don't forsee a happy future for thirsty twins.

As for the "benefits" of new technology - "eg. BRS parachutes, G1000 situation awareness & ease of use, FADECs", all of these are arguably double edged swords; For example;

BRS parachutes - great idea, but are they sometimes used as a substitute for airmanship?

G1000 situation awareness - terrific and I'm a real fan of GPS. Others on this forum will argue equally passionately against GPS for a huge variety of reasons.

FADEC's - A tricky one. I think that what strikes me from reading the Theilert engined sections of GASILS is how often mysterious engine management problems seem to manifest themselves, only for the factory, upon investigating said problems, only to find nothing. Are they fixing the problem and keeping quiet? Is the problem fixing itself? Is the problem a result of mis-handling? Dunno. I for one would prefer to retain a major degree of control over vital systems until this technology is fully developed and gilt-edged; if that entails me staying in the dark ages of magneto's for now, so be it.

To have a "computer says no" situation on a comedy sketch in the comfort of your living room is amusing. To have it on the climb-out into IMC is probably not.

I am now going to my bunker and reaching for my hard hat....:ooh:

[radicalrabit]

Who can afford to shell out £250,000 for new plastic anyway? :ugh: Maybe down south more of you can but I imagine not many of us up here will be making a queue

[Rod1]

It is a lot of money on your own, but 50k from 5 people and you are away. Alternatively you can go PFA, slash the cost down to an affordable amount and save a bundle on running costs.

Rod1
(also north of Watford)

[BackPacker]

I think there are a few distinctions that you need to make here. You can't just simply compare old with new. Sometimes you may have to combine old with new to get your perfect compromise.

Aluminium vs. "plastic" (composite) airframe:
- Lots of experience with long-term behaviour of aluminium structures, both when it comes to (outside) storage and repair. Far less experience in general with composite structures in this respect, outside the sailplane community. And gliders are normally stored indoors - despite UV protective paint, will a composite aircraft like a DA-40 really survive 30 years plus of being stored outdoors? With aluminium, we know that this can be done, provided that certain precautions are taken. With composites, we think it can, but the technology hasn't been around long enough to prove that it can be done.
- Advantage of composite is that it can be formed in two dimensions, which is very hard to do with aluminium. This leads to aerodynamically better designs. Plus: no rivets.

Lycoming/Continental vs. Rotax vs. Thielert
- Direct drive engines like Lycoming and Continental are very robust but need large internal displacements to produce their horsepowers. This is fuel inefficient. Engines with a gearbox like Rotax and Thielert can run at higher revs, with smaller internal displacements, which makes them more fuel efficient.
- Water cooling is far more efficient than fuel/air cooling, but it comes with a price in weight and added complexity
- Diesel fuel (whether Jet-A or automotive diesel) has more energy density, both per liter and per kg than fuels like avgas and mogas, and are easier to refine, thus less expensive. Avgas is a niche market for fuel refineries and 100LL still contains a bit of lead, which upsets the environmentalists. Mogas has problems with European legislation requiring the addition of biofuels, most often alcohol/ethanol, which can cause vapor lock problems. Jet-A, as of yet, is tax exempt.
- FADEC (or whatever name you give it) has the advantage of making engine management, from the pilots perspective, far less involved. Just one lever instead of three (throttle, mixture, prop) to adjust and just one number (%load) instead of at least two (MAP, RPM) to see how much power the engine is developing. FADEC will keep track of engine health (temperatures, turbo pressure etc) for you and is able to store the data for later analysis. But FADEC requires a continuous electric supply which is external to the engine. Whereas magnetos are essentially integrated with the engine and will work regardless of what happens elsewhere.

BRS: Has to be designed/installed by the factory and both the airframe design and BRS design depend on each other. Obviously has a lifelong weight & maintenance penalty and in some cases there is indeed the perception that it is used instead of airmanship.

G1000 or similar - apart from the one-time expense, both in terms of money and training time, I really can't see a downside to this technology. Perhaps in training though: if you've been trained on integrated glass exclusively and then need to swap to steam gauges.

Fortunately, there are a lot of designs out there that combine these new technologies in different ways, and you can pick a design that's best for you. Eg.
Cirrus: Plastic, direct drive engine (don't know whether that's a Lyco or Cont), BRS, G1000
C172: Aluminium, available both with the original engine but also with a Thielert now, and a G1000 if you want to, but no BRS (that I know of)
PA28: See C172 although I do not know if the PA-28 can be equipped with a Thielert straight from the factory.
Diamond: Plastic, both a direct drive and the Thielert engine available, variety of panels, no BRS
A lot of VLA designs now use the Rotax 912, 912S or 914 instead of more traditional, direct drive engines like the smaller Continentals/Lycomings, or the Jabiru.

[englishal]

To have a "computer says no" situation on a comedy sketch in the comfort of your living room is amusing. To have it on the climb-out into IMC is probably not.
It is not an issue with the G1000 types....when the "computer says no" you are left with "only" what all other aircraft have as their primary flight instruments ;) More or less.....With the handheld radio and pocket GPS you are doing far better than some poor sod partial panel in a steam driven aeroplane.

The plastic aeroplanes all come with 25G impact resistant cockpits and seats, and some have airbags. Look at the firewall of a Cessna, even a brand new one. If you stick that into a fence there is not a lot stopping the engine landing on your lap. Stick a DA40 into a fence and it has been designed to protect you (something they didn't even think about 50 years ago, in cars either).

The Titanic was built with not enough lifeboats beacuse it was unsinkable..... I'd rather be in a plastic rocket ship with BRS which has NOT been certified for spinning, than a aluminium spam can that has NOT been certified for spinning without one ;) Touch wood in the last 7 years I have not managed to get into an unintentional spin yet, even in mishandled aero's gone a bit skewy :O (because this is the arguement with BRS).

[IO540]

Times seem to be a changing so would anyone buy a brand new aircraft based on a 40 or 50 year old design from Cessna / Piper / Beech / Mooney /etc rather than one of the newer designs?

To a large degree the question has already been answered. The old stuff isn't selling anymore.

Some aviation rag I picked up the other day (FTN?) said Piper sold just 14 PA28 Archers worldwide in 2006. Piper UK annual sales of piston planes have AIUI been in single digits for years, and it is only the occassional £1.5M turboprop that keeps the whole thing afloat; you don't need to sell a lot of those. Same with the Socata TB; production stopped in 2002 and only the £2M TBM is making money, and making plenty of it too. You need a £2M plane to absorb French trade union practices.

IMHO anybody buying a traditional Cessna or Piper is a fool. Well, a C182 is good for short strips while having reasonable touring ability. But an Archer? Who would pay £150k for something like that.

Mooneys have their followers, and some of them appear to be more aerodynamically efficient than most others; the narrower airframe perhaps? Personally, I don't like single door planes. Also if you look at some of the speed claims, they are way up at high oxygen flow rate altitudes (FL250) and silly fuel flow rates.

Composite is the future, like it or not.

But composites won't be here 30 years from now like the 1970s spamcans are still here. They won't last. Whether anybody will care is another matter, because buying a plane is a straight tradeoff between buying new (and spending next to nothing on airframe maintenance for 10-15 years) and buying old (and spending 4-5 digits annually).

The only reason we see so much old GA junk still flying is because the GA scene doesn't attract people with money to buy new stuff. Also, pilots are conditioned by the anoraks who dominate the GA scene that such and such 1970 piece of iron is actually really good. This will change too, I reckon, as things get modernised.

Personally, I would buy a TB20GT (year 2002/03) again. A fantastic plane, no handling vices, great looks, 2 doors, passengers absolutely love it. It's aluminium but the roof is composite. If you smash the roof you have a writeoff, but how would you smash the roof??

Then there is the lightweight VFR scene, 750kg or less depending on where. This is all composite anyway. These will gradually take over the VFR "sports" market, but are no good for serious mission capability which needs IFR/airways.

[JOE-FBS]

Being new to powered GA and having spent more than a decade in road vehicle powertrain design, I have been amused and I suppose slightly horrified, by engines with carburettors and hence manual mixture control, manual intake air temperature control, no knock control, etc. Are the current production products from Lycoming and Continental still like that? As far as I can tell from those companies' web sites, fuel injection, etc. are at best add-ons and possibly not available at all. Can anyone explain why, please? I know one has to have more reliability in an aircraft but the full authority electronic throttle in your BMW (including Mini) is going to kill you and probably several other people if it fails open so basically it doesn't! This is ten year old car technology and aircraft FADEC is much older (we were designing it into RB211 at RR in the eighties). I am old enough to have had cars with manual chokes but anyone under 30 in Europe and probably 40 in the US will never have heard of such things. How many forced landings are caused by using such ancient technology? Would modern systems reduce or increase this? I don't know the answer but I am, being a techie and a spotter as well as a student PPL, very curious.

[BackPacker]

Joe, welcome to the very conservative world of general aviation, where it takes a very long time for new technology to become certified, trusted and established (and not necessarily in that order).

I know one has to have more reliability in an aircraft but the full authority electronic throttle in your BMW (including Mini) is going to kill you and probably several other people if it fails open so basically it doesn't!

In an aircraft, speed (and altitude) is life. In a car, speed kills. So if given the choice, an aircraft engine design will fail towards a "high power" setting, whereas a car engine design will fail towards the "no power" setting. The idea for an aircraft being that if you have such a failure, the engine will develop as much power as possible so that you can climb to altitude, or go into a climbing cruise, until you've come to an altitude and place where you can glide to a safe landing, hopefully at an airport with long runways. At that point in time you kill the engine.

[soay]

Who can afford to shell out £250,000 for new plastic anyway? Maybe down south more of you can but I imagine not many of us up here will be making a queue.
Last time I looked, you could buy a new Cirrus SR20 for £140,000, while the SR22 starts at £186,000. Buy soon, before the exchange rate worsens, and the Danish VAT loophole is closed!

[JOE-FBS]

Backpacker, good point.

No problem, you make the fail-safe mechanical spring pull the throttle blade open for an aircraft if motor control fails instead of closed which is what is done on a road vehicle.

[wsmempson]

I would suspect that, given most GA products are consumed in the US of A, the fear of "Product Liability" suits has hampered the development of anything new from the Piper/Cessna, Lycoming/Continental camps. I.E. why change something proven for something new, when you can spend time concentrating on making it for less money instead?? Sad, but probably true.
The dominance of the PFA/LSA class by eastern european 2 seaters with rotax's up front promises to change the bottom end of the market quite dramatically; Maybe Cirrus and Diamond will do the same for the middle market.
On the subject of "the computer says no" I seem to remember Ian Seager of Flyer writing eloquently about a trip across the southern North Sea in a glass cockpit cirrus, only to have a minor lightning strike stun the avionics, leaving only a compass, AI and an altimeter to work from. Perhaps things have moved on...
However, even if I had the £250,000 necessary to buy an new 'plastic fantastic', I'd probably still go with an older airframe from one of the usual suspects (piper/socata/cessna) instead and spend some cash on bringing it up to 'as new' condition. I take onboard the comments about having to spend the difference on airframe bits but, against the depreciation cost of ownership from new or nearly new, this seems to be a price worth paying.
Just my opinion based on my limited experience of ownership.:ok:

[BackPacker]

No problem, you make the fail-safe mechanical spring pull the throttle blade open for an aircraft if motor control fails instead of closed which is what is done on a road vehicle.

Exactly. But the same principle is applied throughout the design.

That's one of the reasons that magnetos are still used as well. Magnetos require a short circuit to be shut off. If the wire from the magnetos, through the firewall to the magneto switch breaks off for whatever reason, the magnetos are live.

Other examples are thermostatic valves in water-cooled engines that fail towards the setting that pushes the water through the radiator instead of bypassing it, and prop governors that fail towards fine pitch (in single engine airplanes) so that full power/RPM is available.

[IO540]

I don't think liability and certification are the problems they are constantly made out to be.

They just made brilliant excuses for sitting on one's ar*se because nobody has ever made money by overtaking the attitudes in their own market.

The reason current certified engines are old technology is because the main market - the USA - is very conservative and had always had cheap fuel.

Another thing is that these engines are not inefficient. If you burn a given fuel at peak EGT, or just slightly LOP, and the spark happens at about the right time, there isn't much more that can be done to improve efficiency. In a car that would be no good but that's because a car engine spends most of its time at say 20% power, so it has to be reasonably efficient over a large power range.

The real problem with the old Lycos etc is that they use thin metal sections (to save weight) and need careful management to avoid cracked cylinders etc. Lycoming etc have also had dreadful QA but that is a separate issue. Some of the design is also crap e.g. camshafts that don't get oil on them other than by splashing up, but this is nothing to do with efficiency...

If GA had been developed in Europe, things would be very different. Due to the historically hard to get IR, poor services etc, almost nobody in Europe flies for real and most activity is just for sports/fun, so you get e.g. the Rotax engine.

Attempts to use diesel car engines (Thielert, and ex Merc engine) have not been successful. The result is heavier than the old iron and so far much less reliable.

[soay]

The real problem with the old Lycos etc is that they use thin metal sections (to save weight) and need careful management to avoid cracked cylinders etc. Lycoming etc have also had dreadful QA but that is a separate issue. Some of the design is also crap e.g. camshafts that don't get oil on them other than by splashing up, but this is nothing to do with efficiency...
Attempts to use diesel car engines (Thielert, and ex Merc engine) have not been successful. The result is heavier than the old iron and so far much less reliable.
That reads like you are contradicting yourself. What data do you have to support the statement that Thielerts are much less reliable?

Have you read the Aviation Consumer report (http://www.aviationconsumer.com/issues/37_12/industrynews/5729-1.html) on Thielert reliability? In it, Frank Thielert is quoted as saying that "in 630,000 flight hours, the 1.7 engines have experienced 22 inflight shutdowns and two accidents, but no fatalities or injuries. That pencils out to about 3.5 shutdowns per 100,000 hours, which Thielert maintains is only one-third the rate of other piston aircraft engines". However, Aviation Consumer say "We simply don’t have credible failure rate data for avgas engines", so it's like comparing apples with oranges.

[Rod1]

G-EMMA

Could we tempt you with a T67M?

Rod1

[IO540]

Soay

I suggest you speak privately to people who operate the DA40/42, preferably those who operate fleets of them. Many of them have had half the fleet grounded with engine issues, much of the time.

My guess is that the Thielert issues have been covered up as is traditional in this business. I am sending you a PM with another example.

I don't want to look like I am gloating in this - I'd like nothing more than a new sexy looking composite avtur burning IFR machine to succeed in this decrepit marketplace which so desperately cries out for a new sexy looking go-places machine, to draw in some new blood and new attitudes. I wish this wasn't true. But it really does look like there is some way to go.

If you just rent a DA42 ad hoc, I doubt you will see any problems.

There is a lot of data for avgas engines, over decades, but it hasn't been collected. It's been dispersed among hundreds of engine rebuilders, 99.9% of whom don't post on pprune :) and it will never be retrieved. If people like Lyco have data, and they probably do, they are not going to publish it. It would reveal that while outright breakages are very rare, a large % of their engines don't make TBO due to various combinations of crap QA and engine mismanagement by pilots.

[Contacttower]

na the Firefly doesn't have the appeal, might try one though

Bulldog beats the Firefly any day...much better roll rate and a nice weighty feel.

[Contacttower]

Times seem to be a changing so would anyone buy a brand new aircraft based on a 40 or 50 year old design from Cessna / Piper / Beech / Mooney /etc rather than one of the newer designs?


I wouldn't buy a new Piper or Cessna...IMHO the Warrior and C172 still have some merit as trainers but for anything else they are poor value for money, have bad fuel burn and represent old technology.

Beech and Mooney are perhaps slightly different, they may be as old as the Cessnas and Pipers in terms of when they first flew but they still carry a slightly 'macho' image of a plane with a great big engine and lots of complicated stuff inside of them. I suspect the few that can afford to buy them buy them with the idea in mind that they are somehow 'more of a man' than the people who opt for the 'soft' Cirrus or Diamond. Mooney and Beech have their solid reputations on their side as well which will continue to count for a lot.

Also the new stuff always seems to get bad press, OBA took the plunge and invested in a big fleet of Liberty XL2s...and look how much good that did them.

If I had the money I'd buy something old...some big old taildragger like a Cessna 180/185 or something really crazy like an AN-2. Aviation has never really been about making more ergonomic and easier planes to fly.

[ProfChrisReed]

IO540 wrote:

But composites won't be here 30 years from now like the 1970s spamcans are still here.

My 39-year old composite glider is still going strong, and looks good for another 39 years so far as anyone can see.

It has needed no repairs to the structure from aging (knocks are different, of course), though I do know of hinges (rudder, aileron) beginning to delaminate and needing to be reattached on other composite gliders - these were all noticed on pre-flight or at annual inspections, and were degrading slowly enough not to be a hazard in flight from sudden detaching of control surfaces. This seems to me to be equivalent to losing a rivet or two on an aluminium aircraft.

What does deteriorate on composites is the gel coat if exposed to UV, which is why composite gliders are either kept in trailers or hangared. Modern paints seem to provide as good a finish as gel coat, and are much more UV resistant. However, I can't help with knowledge whether a composite aircraft left outside would suffer airframe deterioration, though I doubt it.

I'm quite certain that a composite aircraft which lives in a hangar when not flying has a lifetime of 50 years +. Many models of glider have had lifetime extensions to 12,000 flying hours, based on their condition at 3,000, 6,000 and 9,000 hours.

[IO540]

The reason I don't think the Diamond type certified composite planes will not be around 30 years from now is not that the material will particularly degrade.

It's just that repairs are harder on composite than on metal.

Recently I was visiting an aircraft factory where they make both ally and composite hulls and the engineer showed me a tiny crack on a composite roof, near a hinge attachment point. He said this will be a major repair job taking several days, whereas on ally you would just rivet a reinforcing plate in there.

If you look at the average 1970s training spamcan, it has had a lot of little repairs. I would suspect that with composites, the trend will be to not do so many.

OTOH once the present ally fleet falls apart (say 10-20yrs from now) and replacements from the USA become scarce, schools will be forced to move to composites as the mainstream. I have no idea how that might pan out.

In private ownership, with careful use, I am sure composites are just fine.

[scooter boy]

One clear winner:

Mooney Acclaim-S.

TKS/TCAS/G1000

end of.

SB

[IFMU]

I don't think liability and certification are the problems they are constantly made out to be.
Certification isn't a problem, just send money. To certify a brand new airplane to part 23 (GA fixed wing), or part 27 (normal category rotorcraft), or part 29 (transport category rotorcraft) costs a large amount of money. I'm sure the same is true of part 25 (Boeing and Airbus territory). Ultimately, to satisfy the bureaucracy of the FAA, you have to generate a weight of paper about equal to the GW of the airplane. This takes man-hours, it takes money. Ultimately you have to earn that money back. That takes profit. So, you either have to make big bucks on each aircraft you sell, or sell a lot of them, or preferably both. I bet that is a lot easier in a part 25 aircraft than a part 23. This is one of the reasons we have light sport aircraft today. Not as much paperwork, not as much costs to recoup. We are still seeing some good LSA's hit the streets, but of course they have limitations too. Limitations on what you can do with them, payload, and speed. Good fun flying airplanes for recreation.

Personally, I don't see the lack of new airframes coming out of Cessna as an indication that they are a bad aircraft company. They have done a realistic assessment of the market, the profit they have to make, and are still building a slightly updated 50 year old airframe. On the other hand, I give some of the more recent companies, like Robinson, Cirrus, and Columbia tremendous credit for having a go at it. Never mind that Columbia is just about to be sold to Cessna.

As far as liability, here in the US it is a problem. It's a bigger problem the bigger the company. The lawyers don't always go after who's 'fault' it really is, just after the deepest pockets. In some ways a startup company is a better vehicle to take the liability risk, as when they start they are all hopes, dreams, debt, and a risky business plan. Take a company like Cessna, with deep pockets, an order book full of Citations, and a huge parent company. Somebody flies a C172 into a granite cloud and for sure lawyers are going to go for the big prize. Sadly one of the prices we pay for our freedoms and our legal system.

-- IFMU

[IFMU]

My 39-year old composite glider is still going strong, and looks good for another 39 years so far as anyone can see.
...

What does deteriorate on composites is the gel coat if exposed to UV, which is why composite gliders are either kept in trailers or hangared. Modern paints seem to provide as good a finish as gel coat, and are much more UV resistant. However, I can't help with knowledge whether a composite aircraft left outside would suffer airframe deterioration, though I doubt it.

I think it is a huge difference that the gliders are kept out of the weather and sun. There is a good reason we put them back in the boxes after we fly. I bet that if you kept your ship outside for 39 years and didn't keep after the paint, that sooner or later that degredation would start to extend to the structure of the glider. The paint on my (sheetmetal) Blanik is pretty poor after 10 years outside, but the sun has little effect on the hard anodized skins. That's one advantage of sheetmetal, assuming you don't end up with corrosion.

-- IFMU

[IFMU]

It's just that repairs are harder on composite than on metal.
There is a glider repair business here in town that takes wrecks and puts them back together. Tails busted off, cracked cockpits, wing damage, they do it all.

At the company where I work we work both in composite and sheetmetal. One of the promises of composite is easier maintanability. I think this is because you don't have to reform the parts, just glue them back together. Then you effectively bond on doublers, analagous to riveting on a patch, but when it's finished it's easier to make it look good.

I don't think it's harder, necessarily. But I do think there are a lot more sheet metal mechanics than there are good composite technicians around today. The good composite guys make it look easy. If, as an aviation community, everybody abandons sheetmetal and goes with composite aircraft, the maintenance industry will support that move. They already do for gliders.

-- IFMU

[Rod1]

There is a document on how to repair composite structures on the PFA site. I had to do a repair on my composite tank, and I have to say it was very simple and much quicker than it would have been if it had been metal. The problem is most engineers are used to repairing metal and are not regularly repairing composites. I am sure when most airframes went from fabric to metal the engineers said it was harder to repair the metal.

My old gliding club had a repair shop which was forever repairing the club fleet and composites did not present any problems. Do not assume all composite gliders are kept in hangers or trailers, almost all of the Grob motor gliders I know of are kept outside. Composite tec has come on a long way since it first became popular in the early 1960’s.

Rod1

[tangovictor]

before departing with my money on a new composite 3axis microlight, I went and spoke with many glider people, most of which leave them out all year round, in our UK weather, with no problems at all, + speak to any composite repairer, and here that most boats are made from the same stuff, and where do boats live ?

[PapaNovGolf]

I'm also very new to GA and have been intrigued about why GA planes still look the same after decades of the same design and technology. And I'm always curious why some of the know-how and lessons learned in the automotive industry cannot be transplanted to GA. Economies of scale through better manufacturing/quality would see prices gradually reduce to a manageable level for the average consumer, ergo more people would get involved in flying. Right now, I don't know about you, but who's got money to shell out to buy an old, clapped out plane that would cost a stack more to maintain? :bored:

[Pilot DAR]

why GA planes still look the same after decades of the same design and technology

It's not that there are not new ideas of merit, but decades of research have resulted in the designs which work, and have all of the "bugs" out. Add to that the cost to certify a new design, after enduring the cost of getting the bugs out, and it is temping to just continue the same old way of doing things, with a design which has long since paid for itself.

New concepts are coming - slowly, but the costs are high, and people are slow to line up to pay a half million for an aircraft which has little more capability than the 40 year old one of the same model.

but who's got money to shell out to buy an old, clapped out plane that would cost a stack more to maintain?

The same person who has the money to shell out for five to ten times the cost for a brand mew one. Using a Cessna 182 as an example, I bought a 1979 model in April, in excellent condition with good times on everything, and flew it home completely snag free for 28 hours. Cost $75,000. Were I to buy a brand new 182, I'm betting $400,000? No differences in performance or capability between the two.

The operating cost of the new one will be quite a bit more. You're insuring a much more expensive aircraft, so much greater premiums. There are systems on the new aircraft (airbag seatbelts for example) which have expensive maintenance requirements, which the older aircraft just do not have. Otherwise, the costs of the older aircraft will not likely be any greater, other than some "wear and tear" items, and maybe corrosion if you're not careful. The 182 I bought will be completely rebuilt so as to be "new", and will still come in under the cost of a brand new 182 wheel plane, though it will now be a diesel amphibian. It will go onward to it's new home in another country.

Aside from the diesel amphibian aspect, this is an "apples to apples" comparison. If you're going to look at a new generation plane, things are different, though the costs are probably comparible. The foregoing is a micro examination of a very large issue. There are lots of other factors.

Also consider that the "old" sheet metal construction is extremely well understood, and easily inspected and repaired. This is sometimes not so straight forward for newer construction methods. They too are repairable, but often not with the desired ease locally.

see prices gradually reduce to a manageable level for the average consumer, ergo more people would get involved in flying

Nice an idea as it is, I very much doubt that we will ever see the cost to manufacture a new aircraft actually compete with the cost of a good to exellent older one, even with some rebuild. Yes, new ones will sell, but not to those people looking for the most economical way to fly. Add to that the cost to get yourself to the point where you're licensed to fly your own aircraft, which itself, is never going to decrease noticably, and "manageable level for the average consumer" is not on the horizon.

It simply costs a minimum to get airborne, and no economy of scale can reduce that much.

[cumulusrider]

In the gliding world I looked after a fleet of gliders for a number of years.
They ranges from wood and fabricwings/metal tube frame fusalage K8s to glass/carbon composite Discus and Ventus. The aircraft with the least maintenance problems and reliablity were the mid 80s composite aircraft.

Over the last few years several major ADs on corrosion on steel and alloy structures in gliders In fact I believe the Blaniks (all metal construction) are currently grounded worldwide due to corrosion problems. This is causing

The earliest glass gliders, Phoebus, libelle etc. are still in regular use.

Yes a lot of gliders are kept on trailers or hangers but we have 20 odd larger gliders live outdoors under covers for 8 months of the year.

I consider composite structure is likely to outlast an alloy one if protected from UV whilst not in use, and re-gelled every 20 yrs or so.

[Pilot DAR]

and aren't subject to crazy government maintenance bureaucracy.

Hmmm, I hope there is no intent to convey that the maintenance standard should be lesser for a non-certified aircraft.... An RV-x aircraft (only as an example) should have a very similar maintenance program to many GA aircraft with similar complexity (Grumman Tiger, for example).

The crazy government people, and delegates like me, who spend time assuring that maintenance information for aircraft is appropriate, and well documented, hope that all aircraft are effectively maintained. The basis of certification (or not) for an aircraft should not influence the content of it's maintenance program, the nature and systems of the aircraft should form the basis to determine the appropriate maintenance.

And, of course, proper documentation of the maintenance accomplished is always important, regardless of the type of aircraft upon which the maintenance was accomplished, or who accomplished it.

[Genghis the Engineer]

Hmmm, I hope there is no intent to convey that the maintenance standard should be lesser for a non-certified aircraft.... An RV-x aircraft (only as an example) should have a very similar maintenance program to many GA aircraft with similar complexity (Grumman Tiger, for example).

The crazy government people, and delegates like me, who spend time assuring that maintenance information for aircraft is appropriate, and well documented, hope that all aircraft are effectively maintained. The basis of certification (or not) for an aircraft should not influence the content of it's maintenance program, the nature and systems of the aircraft should form the basis to determine the appropriate maintenance.

And, of course, proper documentation of the maintenance accomplished is always important, regardless of the type of aircraft upon which the maintenance was accomplished, or who accomplished it.

The standards don't want to be significantly less, but the beaurocratic overheads can be.

The EASA system keeps adding management complexity without apparently adding safety (indeed, the paper chasing versus allowing good technicians/engineers to just get on with maintaining flying machines they understand often seems to be anti-safety).

Various sub-ICAO systems such as those of the LAA and BMAA do seem to manage equivalent standards and safety, whilst massively cutting the management aspects.

G

[Ex FSO GRIFFO]

G'Day Pilot DAR,

Can I enquire what sort of diesel you are putting in your 182?
And do you require a reduction gearbox?
And would that be water cooled?
Just curious is all....

Cheers:ok:

[Croqueteer]

:ooh:I think future problems will be caused by building down to a weight to meet unrealistic targets in the small aircraft field. There is something to be said for a bit of over engineering to give airframes a long life like the current older generation.

[IO540]

"Plastic" doesn't save much weight. Today's very light types have been achieved by using minimal-strength materials and structures, and stripping out "luxury" items like interior trim.

Pressing on the cowling of a typical 450kg type with one finger deflects the material about 1" :) Hardly suprising.

This delivers a significantly lower cost means of getting airborne than previously possible, and on paper at least they claim the same G ability as certified types, but there is no denying lots of corners have been cut.

Pop down to the Aero show at EDNY in April this year and have a good look around to see how it is done. They have hangars full of this stuff.

[FlyingStone]

"Plastic" doesn't save much weight.

I couldn't agree more. For example if we compare DA20 and PA38, with all that composite materials, single fuel tank, much smaller tail (both horizontal and vertical surfaces) and fuselage near the tail, and more or less the same engine weight: the difference in empty mass in is virtually zero. Same goes for MTOM, which is actually few kilos smaller for DA20 (at least in Europe, thanks to wonderful EASA :ugh: ). So basically, plastics doesn't save the weight as much as one would expect, but I rather do high-load manuevers (staying in the limits of course) in any new aircraft (plastic or metal) than in 40 years old spamcan :)

[Jan Olieslagers]

Do I remember right that, for the strength to weight ratio, aluminium scores best, followed by wood, only then composites, and steel last?

As I understand (and as already mentioned higher up) the main advantage of composites is in the easy creation of complex curves. Carbon-fibre does seem to offer substantial weight savings, hence its use in the latest generation of airliners.

For industrial production, composites will be more expensive than the other materials due to the lots of manual labour involved.

So I would expect the optimal aircraft to be built of aluminium, with complex bits such as the tips and roots of wings made of composite.

[Genghis the Engineer]

Depends what you mean by "strength" Jan - tensile? compressive? buckling?

There's also huge cost implications - CFRP for example will beat anything, but at huge cost.


Materials engineers use something called a "Figure of Merit" that analyses a component's strength requirements, and done well it incorporates material and manufacturing costs to show the best material for a particular application. Even then however, it gets more complicated because you really don't want 12 different material/technique combinations in a light aeroplane because of the huge equipment and training overheads that imposes on you, when you'd rather be slightly sub-optimal but only have 5 processes in a particular aeroplane.

It was this use of far too many materials, in my opinion, that was one of the main reasons that British company CFM folder (they used to build a rather nice little aeroplane called the Shadow). The aeroplane was original designed for amateur builders and for them, having a dozen different techniques to learn was fun, but in a factory environment it was a disaster and they just couldn't build it economically.

G

[Rod1]

“"Plastic" doesn't save much weight. Today's very light types have been achieved by using minimal-strength materials and structures, and stripping out "luxury" items like interior trim.”

Unfortunately the term "Plastic" covers a big area. Certainly, GRP is not going to save you much, but carbon fibre will save you a lot, at significant extra cost. If you compare two aircraft in the same class with the same g loading, engine and similar props it is possible to get an idea of the magnitude of the saving;

MCR01 club (lots of expensive carbon) empty weight 253kg
SportCruiser (much lower cost, metal) empty weight 335kg

Both aircraft have been tested to CS-VLA by the same organisation, both have the same engine, the MCR has a VP prop, the SportCruiser in my example has fixed pitch.

I have a friend who is designing an aircraft to lift a 90kg pilot on 24hp to cruse at 90kn. His spar is carbon, as are some of the other critical and heavy bits, the rest is wood, which is light but very time consuming to work with.

Rod1

[Jan Olieslagers]

I have a friend who is designing an aircraft to lift a 90kg pilot on 24hp to cruse at 90kn. His spar is carbon, as are some of the other critical and heavy bits, the rest is wood, which is light but very time consuming to work with.

His name wouldn't be Michel Colomban, by any chance? Sounds suspiciously like the Luciole - only that design is done, and a fair number are flying.

[Genghis the Engineer]

A follow up point. Personally I think that materials is one of the least interesting ways of improving aeroplanes.

We all know about avionics options - just for example I did a couple of hours yesterday with a Garmin Aera sat on the top of the instrument panel. The amount of mental capacity it freed up for me to enjoy the flying and concentrate on my situational awareness was impressive. Not only that, but the ability it gives me on a cross country to cut VERY close to controlled airspace and danger areas without entering them saves me a lot of time and fuel: I think that a reasonable moving map GPS probably pays for itself in under a year of touring flying.

Engines? The Rotax 912 has massive advantages for light aviation, even if it still has it's faults - it's cheaper, lighter, easier to operate, and burns less fuel than equivalent "Lycontinentals". Just look at what it's done for the new Tecnam twin! Diesel light aircraft engines are still in their infancy, but they'll come.

Ergonomics? - This is the bit that's being most ignored at the moment, but there's been a lot of work in improving cockpit ergonomics and handling for best safety (see the article in the latest GASCo Flight Safety for example), some manufacturers are using this - I know that Cessna has in the C162, but frankly some of the latest generation of light aeroplanes are years behind their 1960s competitors in this regard. The problem is that whilst it improves safety, it doesn't make aeroplanes "sexy" (indeed, possibly the opposite).

G

[Rod1]

"His name wouldn't be Michel Colomban, by any chance?"

No, his machine has a max pilot weight of less than 90kg, but the aircraft does use the same engine / prop.

BR,
Rod

[Pilot DAR]

Ex FSO,

(excuse the thread drift, but the "old Yank metal" will have new plastic floats!)

My diesel 182 project is a work in progress, as I am still waiting for the SMA engine I ordered last March. It will be installed in accordance with the SMA STC for the 182. To this, I will add other mods, primarily amphibious floats. All of this is for a Norwegien client.

SMA's shift of emphasis to their new "E" model engine has caused a delay in our original plans, so we wait... also watching with interest what the Continental does under Chinese direction....

I have promissed SMA that I will take the 182 amphib to Oshkosh for their display, if they get an engine for me time to complete all the mod work!

[A and C]

So far in less that a year maintaining one of these VLA's I have seen landing gear cracks, exhaust system cracks and a very pooly built brake system all on aircraft with less than 150 hours on them.

It won't be long before the steps fall off and there are big dents in the roof.

What the training industry needs is Lycoming to get the FADEC controled mogas engine into the market and give the Cessna 152 another thirty years of life.

[Mickey Kaye]

A and C

Do tell which one was it?

[A and C]

Mickey

I work on a number of this type of aircraft but I don't see it has any value in picking this type out, the problem is that most of the VLA's are under built in terms of robustness.

I was of the opinion when I first looked at the current crop of VLA's that most would make very good private or small group aircraft aircraft but would never take the treatment that is dished out to flying club aircraft. I have had to adjust my opinion in the face of the failure of parts of aircraft that are in service with very careful private owners.

The fact that most of this type of aircraft are now getting upgraded parts to replace the items that are failing and these parts are all much better built however with this comes more weight and this is most critical on VLA,s.

I have no doubt that as a private aircraft these types will get "sorted" but the stunning performance numbers will be blunted by the weight increase that will be required by the need for reliablity.

I expect to find a number of conflicting opinions posted below from fans of this type of aircraft but all I can say is most of the people don't have to put their name to the paperwork for the CAA permit or LAA release to service.

[Genghis the Engineer]

There's a parallel there I think A&C in the microlight world.

Microlights have been being made down to a low weight limit for over 30 years, whilst meeting pretty much the same structural requirements as VLAs (JAR-VLA, which is now CS.VLA was actually based upon BCAR Section S, the UK microlight regulations).

Some microlights have definitely proved to be robust enough to last for years in a club environment - the Thruster and AX3 for example, and there's a Shadow I know of that's done 4000 hours in a flying school - although that's probably an exception. On the other hand, many: the Chevvron and Spectrum for example (interestingly both mainly composite!), which were really well regarded when they came out in the late 80s just haven't lasted and there are only a few of each still flying.

I'm sure the same will prove the same for the new crop of VLAs - some will last the course, some won't. It's certainly interesting however to conject which ones. And whether there will be an obvious metal:composites split.

G

[Jan Olieslagers]

Another example of a rugged microlight that can cope with the hard life a plane gets in training is the Rans S6 Coyote. Like the Shadow, this plane was not designed to be the fastest sleekest sexiest around, it simply does its job of pleasure flying.

[Genghis the Engineer]

Another example of a rugged microlight that can cope with the hard life a plane gets in training is the Rans S6 Coyote. Like the Shadow, this plane was not designed to be the fastest sleekest sexiest around, it simply does its job of pleasure flying.

Although as a kitplane, I think that in most countries the S6 can't be used for commercial training. It certainly can't in the UK anyhow.

G

[IO540]

Is there any way to inspect a composite hull+wing structure for hidden damage?

There have been too many in-flight disintegrations following an unreported ground taxi incident, in composite (incl. wood) aircraft.

[Jan Olieslagers]

Quote:
Originally Posted by Jan Olieslagers http://images.ibsrv.net/ibsrv/res/src:www.pprune.org/get/images/buttons/viewpost.gif (http://www.pprune.org/private-flying/302036-brand-new-old-yank-metal-v-new-plastic-fantastic-3.html#post6154748)
Another example of a rugged microlight that can cope with the hard life a plane gets in training is the Rans S6 Coyote. Like the Shadow, this plane was not designed to be the fastest sleekest sexiest around, it simply does its job of pleasure flying.

Although as a kitplane, I think that in most countries the S6 can't be used for commercial training. It certainly can't in the UK anyhow.

It certainly is over here, actually I took a good deal of my training in one, including my first crash. I understand the trick is to assemble one plane from a kit, present that plane for certification, then assemble all subsequent kits to the same standard - more or less. The Belgian authorisation is for a "Rans/Confluence Coyote", Confluence being the distributor.
Not clear what you mean by "commercial training", though - all of my training was done in club environments.

[Genghis the Engineer]

Commercial = being paid for.


The rules on what you can do with sub-ICAO aeroplanes do vary massively between countries.

G

[Jan Olieslagers]

Commercial: thank you, I did study English at school. Are you really implying there is training available that one does NOT have to pay for? Are you then saying that ALL training is commercial?

As for the rules: yes they do vary between countries. And even the rules that ARE identical between countries often get widely different interpretations.

[Genghis the Engineer]

In the UK, training on type is routinely done by experienced pilots within syndicates. I've certainly never either paid, or been paid, for that sort of training.

G

[Jan Olieslagers]

(sorry to go off-topic, i was going to PM this, but then I thought I'm perhaps not the only foreigner trying to understand the UK and its err hm traditions)

And by a syndicate I suppose you mean a plane equally owned by a group of pilots? When someone steps out, the share is sold to a new owner who must then get acquainted with the plane? That kind of training I would call "difference training" or "conversion training"; but I think that formally it can't even be called training - training is working towards a license. And yes it does have to be paid for.

[Genghis the Engineer]

You are correct about syndicates.

Training other than that, doesn't need to be paid for - it's just normal. If an instructor is a friend, or within a syndicate, they may well do it for nothing.

There's also a UK legal loophole that allows the sole owner of a sub-ICAO aeroplane to pay for training, but that same aeroplane can't be used in a flying school.

G

[Jan Olieslagers]

Thanks for patiently explaining, sir! Time to get back on topic?

[Rod1]

A and C

I suspect you are talking about the SC, which has had a lot of problems. The number of aircraft designs, which have been tested to CS-VLA, is quite large. Some of those aircraft are better than others and to criticise an entire class because one or two of the traditional metal designs are not up to the job is a little hard. My “VLA” has required the changing of one set of brackets in nearly 5 years of operation (supplied free). The other aircraft I help look after have required very few mods and are all in “as new” condition after 5 – 10 years of operation. None are being used for flight training, but most “VLA” types are privately owned, so this is not surprising.

Rod1

[bingoboy]

Comparisons lead to generalisations.
In terms of longevity I know of a C42 which has well in excess of 3000 training hours in relatively few years.
The training world does bring challenges and the old yank metal has seen many fail to make it and even the C150/2 has had issues.

As for the thread; I remember the US car industry and indeed consumers finding it hard to react to the Japanese threat.

Downsized vehicles and downsized engines were just a couple of the issues and it took the consumers, esp in Calif., to change things.

The rise of the SUV and the popular personnal trucks is probably the new/old metal swansong as fuel prices continue their inevitable rise.

As G3 says the prime material probably doesn't matter. Economical engines and a lowcost designed in maintenance schedule will be the way forward. As to which manufacturers find the solution the market craves only time will tell but I am sure that many current new aircraft will have short production lives and a few will become the future of GA. (at least for a decade or so)

[IO540]

Reading between the lines of some of the airworthiness issues, I think there is a fair bit of test flight data forgery going on, and hand in hand with that will be a fair bit of Thielert-style dodgy business accounting.

So I would expect the "lightweight" scene to be fairly "dynamic" for quite a while ;)

The vast majority of the stuff exhibited at Friedrichshafen never makes production, so it follows that a fair % of the stuff which does is a variously marginal proposition.

[Rod1]

“So I would expect the "lightweight" scene to be fairly "dynamic" for quite a while”

How long IO? Some of the aircraft (which have been tested to CS-VLA) have been around 12 years and have 7-800 examples flying. Some of the airframes are up to serious numbers of hours.

Rod1

[Genghis the Engineer]

I'm not sure it's forgery so much IO540, as sheer incompetence. A lot of the people I've come across in the little aeroplane industry doing test flying, or in the authorities interpreting the results, really don't understand what they're doing.

This isn't to say that there aren't some supremely competent people in this game - but that skill level really isn't universal. By comparison, the level of understanding of structural issues is usually much better. Detail design and maintenance quality probably sit somewhere in between.

Additionally, both company management and authorities will normally be very ready to accept absolute minimum standards in flying qualities, which makes it very hard for even very competent flight testers to get changes made that they think are necessary. A friend of mine is a very competent test pilot for a very well known US GA manufacturer, who I know has had a real struggle to get his design colleagues to accept handling qualities changes that weren't required by regulations but he considered essential for safety - and that's a company with a strong flight test department and safety culture: many newer or smaller companies have neither.

G

[Genghis the Engineer]

Comparisons lead to generalisations.
In terms of longevity I know of a C42 which has well in excess of 3000 training hours in relatively few years.
The training world does bring challenges and the old yank metal has seen many fail to make it and even the C150/2 has had issues.


Interestingly in the UK the two microlights which seem to have lasted so long have been the Thruster and AX series; the C42 has virtually the same construction (known as "bolted fuse-tube").

So, I'll make a prediction that most of the current generation of aircraft that have very long lives in large numbers will be those with the fuse-tube construction (Rans, C42, X'Air) and the conventional sheet metal construction (Eurostar, RV). In 20 years there will still be MCR-01s, Dynamics and CTs, but I suspect in much smaller numbers.

G

[patowalker]

So, I'll make a prediction that most of the current generation of aircraft that have very long lives in large numbers will be those with the fuse-tube construction (Rans, C42, X'Air)

Far be it from me to argue with an expert, but I thought the Rans had a welded steel space-frame, rather than a bolted fuse-tube.

[Shoestring Flyer]

'I suspect you are talking about the SC, which has had a lot of problems.'

Sorry Rod but that is not quite fact!...There are 91 Sportcruiser/Pipersports that have been registered in the 3 and a half years the type has been available in the UK. The only 2 issues that some owners have had is a slight problem with cracked exhaust downpipes and some have had bent noselegs due to poor landing technique. Both problems have had generously supplied free factory replacements where needed although both have been, in the main, issues that have been due to pilot error. The majority of owners, of which I am one, have had no issues whatsoever.
The sheer number of purchasers in such a short space of time I think tells its own story....The plane is an on-going huge worldwide success story and that is why Piper have jumped on the bandwagon and negotiated a licenced to build agreement with the factory and 'rebadged' it a Pipersport.

There are 31 MCR's that have been registered since 2002 of which there is no longer a UK agent ( is the plane still being made in France?)They have had a lot more issues I think than the S/C including serious metal fittings corrrosion (aileron/flap?)and also have had a fatal accident resulting in 'free replacement taliplane brackets being available'.
Whilst admitting that the MCR has been an interesting little 'hot ship' within a very niche market envelope I would suggest it is now probably at the end of its build/availability life in the UK.

The MCR and the Sportcruiser are two totally different beasts and both I am sure have pro's and cons and are fir for purpose depending on one's own personal requirements.. In reality I think its a case of each to his/her own.

[Mickey Kaye]

Shoestring flyer

Unfortunately as of yet the SC/PS hasn't been used in the training environment. Here "poor landing technique" and "pilot error" will be commonplace . If and when its proves itself in this environment then I would consider it a success.

[Shoestring Flyer]

Mickey Kaye

We are talking from a different perspective. The S/C is a worldwide success in the private owner market.
I totally agree with you that the S/C or the AT3 or Tecnam or any others you may care to mention that hope to try and capture a slice of the training market are not nearly robust enough.. But they were never designed initially for the training market.
Its a diifferent ball game.

[Genghis the Engineer]

also have had a fatal accident resulting in 'free replacement taliplane brackets being available'.

The accident where a tailplane came off in flight, remarkably enough, wasn't fatal. That said, the injuries were pretty horrendous. On the other hand, surviving a tailplane coming off at 500ft is pretty impressive, and in my opinion a major factor was the energy absorbing composite structure of the MCR-01's forward fuselage. Composite aeroplanes can be the best ones to crash (so long as they don't burn anyhow!).


Far be it from me to argue with an expert, but I thought the Rans had a welded steel space-frame, rather than a bolted fuse-tube.

Argue away, but it's aluminium alloy tubes secured to junction plates by a combination of bolts and rivets. The engine mounts and some of the structure immediately around the cockpit are welded, but not much else.

http://www.ranss6s.com/3-20-06-1.JPG
http://www.ranss6s.com/8-30-06-001.JPG

G

[Shoestring Flyer]

'The accident where a tailplane came off in flight, remarkably enough, wasn't fatal'

I stand corrected.

[patowalker]

Thanks for the explanation and pictures Genghis. I should have known that factory claims about the safety of a welded steel cockpit did not necessarily mean the rest of the fuselage was also welded steel.

[glush]

Regarding the SC problems, I seem to recall an MOR last year where pressing the PTT activates the elevator trim. It resulted in a SC taking off with full nose up trim applied! It was caused by an inadequate design of the switch assemblies in the control sticks.

Then we had the grounding of SC's for a couple of weeks by the CAA due to there being no performance data for aircraft with a certain type of propellor (factory fitted). Apparently the manufacturer has been given until February to update the POH.

Finally, not sure I can go along with the concept that the only reason for the nosewheel leg deforming is due to poor landing technique... If that was the case for PA28's and C152's they'd be in with the engineers on a weekly basis having new nosewheels installed! Why was a re-design and beefier version implemented on later SC aircraft if that was the case?

[patowalker]

Regarding the SC problems, I seem to recall an MOR last year where pressing the PTT activates the elevator trim. It resulted in a SC taking off with full nose up trim applied! It was caused by an inadequate design of the switch assemblies in the control sticks.Nothing wrong with the design of the Ray Allen G205, which is used on many thousands of aircraft around the world. Unfortunately, it can only take one example of sloppy soldering to lead to an incident and you end up with a SB.

http://www.czechsportaircraft.com/pdf/10-07-02_SB-SC-001-R1.pdf

Then we had the grounding of SC's for a couple of weeks by the CAA due to there being no performance data for aircraft with a certain type of propellor (factory fitted). Apparently the manufacturer has been given until February to update the POH.Only a clerical error. :)

Finally, not sure I can go along with the concept that the only reason for the nosewheel leg deforming is due to poor landing technique... If that was the case for PA28's and C152's they'd be in with the engineers on a weekly basis having new nosewheels installed! Why was a re-design and beefier version implemented on later SC aircraft if that was the case?Are you suggesting that no PA28 and C152 parts have ever been beefed up or re-designed?

[A and C]

Correct on all counts.

The nose leg that I replaced was fitted to an aircraft that was only flown by an ex-airline pilot with thousands of hours in the log book, the aircraft had less than 50 hours.

That being said the new nose leg looks well up to the job but with a propotional increase in weight.

[Genghis the Engineer]

Correct on all counts.

The nose leg that I replaced was fitted to an aircraft that was only flown by an ex-airline pilot with thousands of hours in the log book, the aircraft had less than 50 hours.

That being said the new nose leg looks well up to the job but with a propotional increase in weight.

Playing devils advocate, I wonder how many of that pilot's hours were on aeroplanes under 750kg.

G

[A and C]

I would guess quite a few on aircraft under 900KG but I am not sure about 750KG.

[IO540]

It's pointless debating the relative structural strength of 750kg versus say 1200kg machines.

It's not just the interior trim the former ones do away with. Everything is really thin. Even the control cables and their attachments are cut down.

As I say, pop over to Aero (http://www.aero-expo.com/) this year and see for yourself. You get a lot more in terms of a "flying machine" for your £80k, and it is probably the only way to buy something brand new and shiny, but don't kid yourself that it will be built to last - especially operated on typical grass strips for years.

And the fuel flow will always be very similar for a given thrust (IAS) and a given cockpit cross-sectional area. The engine type barely comes into it. A Rotax and a Lyco will deliver very a similar SFC.

[Justiciar]

Presumably the modern training market is what the Cessna Skycatcher is aimed at? Is that aircraft any more robust than the SportCruiser/PiperSport? I don't have huge experience of LSA but my Pioneer certainly needed some tidying after 500 hours. If the new breed of LSA with Restricted Type Certificates, of which there are currently only a very small number, are not anyway robust enough for training then the available modern aircraft suitable for training would appear to be very few

[Genghis the Engineer]

The structural requirements that have to be complied with for light aeroplanes (CS.23 and FAR 23), very light aeroplanes (CS.VLA) and microlights (BCAR Section S) are all basically the same.

The new US LSA category however does seem to set some rather lower standards and I imagine that those are what IO540 is describing. I had a conversation not long ago with one of CAA's more senior airworthiness engineers who clearly regarded EASA's discussions about giving those aeroplanes full Certificates of Airworthiness as barking mad. I agree with him.

G

[W2k]

The flying club I'm with is currently in the process of replacing some of its 'old yank metal' (PA-28-161) with a 'new plastic fantastic' Dynamic WT9 (http://www.dynamicaero.org/description.htm). Rotax, FADEC, glass, carbon/composite, factory new. Of course I'm looking forward to exploring the differences myself but I'm curious if anyone has experience with the WT9?

[Rod1]

IO is mistakenly aiming his comments at aircraft tested to CS-VLA, hence his 750kg above which only applies to VLA’s. LSA is restricted to 600kg and is a US only std.

Rod1

[Genghis the Engineer]

The flying club I'm with is currently in the process of replacing some of its 'old yank metal' (PA-28-161) with a 'new plastic fantastic' Dynamic WT9 (http://www.dynamicaero.org/description.htm). Rotax, FADEC, glass, carbon/composite, factory new. Of course I'm looking forward to exploring the differences myself but I'm curious if anyone has experience with the WT9?

Yes, I've flown several variants - but there are several variants I've not flown.

General impressions were of a high performing, very nice looking aeroplane whose handling is mostly well sorted. There are however certainly variants with distinctly poor stalling characteristics, and most variants have far too little available payload. I'd recommend that your club check the stalling characteristics themselves of each aeroplane before accepting it, and have a good hard look at the weight and balance also.

G

[W2k]

Genghis the Engineer: Many thanks for the advice, will be sure to pass it on.

[IO540]

The structural requirements that have to be complied with for light aeroplanes (CS.23 and FAR 23), very light aeroplanes (CS.VLA) and microlights (BCAR Section S) are all basically the same.

There is however a big potential difference between 2 planes, both rated at say +3.6G or whatever, in that one can be a lot more robust than the other.

One can't put figures on everything, which is why some planes are a lot stronger than others, in terms of in-flight breakups over many years.

[Cows getting bigger]

I think we are in danger of comparing apples with oranges here. Someone has already pointed out the difference between LSA (an American thing) and CS-VLA (European). It seems to me that a number of the VLAs also fit quite nicely in the LSA category with a bit of tweaking - I wonder why. :rolleyes:

Regardless, I thing the broad-brush that some use to criticise these new pretenders is, err, rather broad. For example, take the Aquila A210 which is a VLA and most definitely a fine aircraft. It may be expensive and it may get tatty in a club environment but............

[Genghis the Engineer]

There is however a big potential difference between 2 planes, both rated at say +3.6G or whatever, in that one can be a lot more robust than the other.

One can't put figures on everything, which is why some planes are a lot stronger than others, in terms of in-flight breakups over many years.

Care to explain with numbers?

Cessna and Piper design to my certain knowledge, as close to the regulatory limits as they can, but have little history of in-flight breakups.

G

[patowalker]

The new US LSA category however does seem to set some rather lower standards and I imagine that those are what IO540 is describing. I had a conversation not long ago with one of CAA's more senior airworthiness engineers who clearly regarded EASA's discussions about giving those aeroplanes full Certificates of Airworthiness as barking mad. I agree with him.

I believe most of the European aircraft sold as LSA in the US are built to CS-VLA. Otherwise, the Sport Cruiser, for example, would not have been granted a permit to fly in the UK.

[IO540]

Cessna and Piper design to my certain knowledge, as close to the regulatory limits as they can, but have little history of in-flight breakups.That's probably why they weigh more. More metal here and there. There's no free lunch.

[Genghis the Engineer]

To the best of my knowledge Piper and Cessna design to 3.8g plus a 1.4 safety factor, VLAs to 3.8g plus a 1.5 safety factor, and UK microlights to 4g plus a 1.5 safety factor. Pretty much the same numbers all round - it's the LSA (and German or Czech Ultralights, who really don't apply appropriate factors) that would worry me.

What are your statistics on in-flight breakups by the way? I'm not aware of any significant incidence in certified (or UK Permit) aeroplanes. I can think of a PFA Cuby, and a CofA PA28, both about ten years ago, but little else.

G

[Cows getting bigger]

If Cessna are so good at designing/building aircraft how come:

The average 172 has 13 fuel drains
The average club 152/172 has more ripples on its firewall than a Cadbury's Flake
The average 152/172 goes through nosewheel shimmy dampers (thank you Lord ;)) more quickly than I can type.

[tongue removed from cheek] :)

[seat 0A]

I wonder how many of these plastic fantastic kits will still be flying 48 years from now. My twin comanche from 1963 (previously owned by Douglas Bader) is worth more today then it cost new. Ofcourse a lot of money has gone into maintenance over the years.
Now if only there was an STC for mogas on the IO320............

[Rod1]

“I wonder how many of these plastic fantastic kits will still be flying 48 years from now”

Well I sincerely hope mine is not. I hope it will have been scraped and replaced by something much more efficient.

Rod1

[A and C]

Quote:- The average 152/172 goes through nosewheel shimmy dampers (thank you Lord ) more quickly than I can type.

I have two Cessna 152's with more than 3000 hours in service with my company and right at the start I chucked away the old and leaking shimmy dampers and have had no more problems, I would guess that the problem is that the dampers on the aircraft that you fly are not being maintaned IAW the maintenance program or should have been replaced years ago.

[gasax]

No one has mentioned the 'super factor' which is applied to composite aircraft. This is an additional 50% reserve which is intended to compensate for the difficulty in inspecting many of the components and joints.

So if the airframe has been carefully put together then theoretically a composite airframe should be a lot stringer and so last considerably longer. It is this factor which largely eliminated the potential weight saving from composites. So long as it exists it would be reasonable to expect composite airframes to be us for a vedry long time...

[Genghis the Engineer]

If the superfactor were not used, you'd definitely see a significant number of in-flight breakups.

German Ultralights in the 1990s were commonly composite, they certified without the superfactor, and the in-flight failure rate was not healthy.

Indeed, many airworthiness engineers worry that the factor is still too small.

Incidentally, the composite superfactor has two components: 20% for material variability, and 30% for through-life degradation. You can reduce it down to 30% by testing a significant batch of materials at maximum representative operating temperatures.

G