Sport Pilot Talk

rsteele · Joined: 12 Feb 2007 Posts: 261

I assume that the economies of scale just don't apply to planes like they do to cars. When I visited the Zenith kit plant in Mexico, Missouri, I was really surprised at the amount of hand work that is done. They have a CNC router to cut out parts and a stamper to form ribs and such for their more popular kits, the less popular are basically hand built. Even welding the fuel tanks is done by hand (and beautifully I might add, I just got mine). Some day, I'd like to visit their sister plant, AMD, in Georgia, I'd bet it's the same way.

For a company like Cessna, you wonder if they couldn't amortize the cost of expensive forming machines across their entire line and really cut the cost.

Ron

Cub flyer · Joined: 10 Sep 2006 Posts: 593

There is a urethane you can pour over a part and cast molds that will survive the stamping process.

Send the hand formed parts to an outside stamping vendor.

Probably would need to buy at least 200 but that's ok.

The main parts are cowl parts, Door pillars and bulkheads.

I can form them with wooden form blocks and hammer by hand to get the shape right on prototypes and then ship off the form blocks for mold casting.

The T-4 6061 does not lose strength with Tig welding.

Cub flyer · Joined: 10 Sep 2006 Posts: 593

I forgot to mention. And Rotax drivers note.

The Vagabond, taylorcraft, aeronca, cub etc. all used the A-65 continental.

Redline is 2300 RPM

Max cruise is 2150 RPM.

very lightly stressed powerplant. Just wait until oil temp warms to 75 deg and takeoff.

With proper baffles or Eyebrows as in the Cub no CHT or EGT guages needed. No engine monitors. Just a mechanical tach. oil temp and oil pressure.

Not finicky about oils, rpm, throttle use, idle time

No water cooling, thermostats, chokes, carb balancing, burping, oil lines, preoiling lines.

Thats what LSA needs is a real reliable idiot proof engine. from the things The things have seen wrong with these engines due to poor or no maintenance and they still ran I am amazed.

TBO on the 65 is 1800 hours. But that was figured out years ago when they only had mineral oil and no filters.

Modern oils and a filter kit it will last much longer. Corrosion from sitting around is the biggest enemy.

Starts every time first try. I don't even have impulse couplings on my mags.

Why can't they make something like this again? Simple and cheap.

The Jabiru is not the answer unless they get more displacement and lower RPM.

tadel001 · Joined: 12 Mar 2007 Posts: 251

If you want to see what is involved in building an aircraft, download this:

http://www.sendspace.com/file/pey3ol

Cub flyer · Joined: 10 Sep 2006 Posts: 593

Great photos. Thanks.

Some things I notice.

They are heat treating formed parts. The heat treating takes the corrosion resistance out of the aluminum so it needs to be painted and corrosion protected internally.

We have thousands of Cessnas and Pipers over 30 years old without any corrosion protection. Just take care of your airplane. Corrosion protection could be optional for coastal areas

When Piper made wing ribs from built up aluminum parts riveted together each rib weighed 7 oz. But people needed to rivet them together with an automatic feed riveter. Univair started making stamped ribs but increased thickness for strength at 14 oz. Over 32 ribs that adds up.

When Piper reproduced the super cub in early 90's they made half thickness stamped ribs and heat treated for strength to get back to the 7 oz weight.

What the needed corrosion protection weighed I don't know.

The Paint weight on a average single cessna outside is around 30 lbs when new.

Epoxies are heavy so by painting all inside parts how much weight does Tecnam add?

Would it be lighter and faster to use slightly thicker parts and not heat treat? Production would speed up considerably. Cessna and Piper did not heat treat to this degree except on a few parts.

Lots of the higher end production airplanes had parts dipped in hot zinc chromate before assembly. This might also be faster and cheaper than Epoxy. My apache is zinc inside and has no areas of corrosion after 20 years outside storage.

They are building a beautiful airplane that should last for 10,000 hours in a training enviroment. I looked close at OSH and was really impressed. Sealed seams, great sheet metal etc.

Do we really need an airplane this nice for SP training? Initial ownership?

Just a cheap stout flying box with windows and tough landing gear will do fine. Zenith is close but hung up on the STOL stuff.

For US production there are a lot of places which can stamp shapes like Univair. Let them handle the cost of maintaining the large machines. Supply them with your own production molds.

Then use a milder aluminum for formed parts and alclad sheet for flat bent skins. Square off the airplane a bit to allow most part to be brake bent. Then any screen door manufacturer could do the bending.

Water jet cut the skins and match hole punch the rivets. Then very little drilling or deburring.

Keep costs down and simplify production. Speed is everything.

A flying box does not have to be ugly or draggy. Look at the Wittman tailwind, Found Bushhawk, Rans S-6 or Bearhawk.

Only thing I don't like about the Tecnam twin is you open the door and step into a propeller.

tadel001 · Joined: 12 Mar 2007 Posts: 251

The heat treating strengthens the metal. Then they do the corrosion protection. Yes, these are very well built aircraft. Tecnam brought their existing line over here and did great a new line. Their aircraft are basically built to the part 23 standard.

The twin has two doors, one in the front of the engine and one behind the engine. It is an amazing airplane.