Training PPL in Homebuilt

[BoostedNihilist]

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[Strega]

Can you provide me some further info on this?
Wood is a good material, but there are many others that are better ie glass

Glass is good, I did outside loops in the glass T67M with the flexibility of the wing showing!

If the glass is not properly cured then there can be disaster, the Sukhoi 31 got off to a bad start when one wing failed under load in the USA. There was big trouble over that one!

Wood is reliable, even when it fails.

In spite of what has been said here about the Citabria, although the wing spars were found to have splits and cracks they had not actually failed in flight.
One set of wings did fold in a Citabria, inverted, when the metal struts gave in!
Wood cracks, warns, cracks some more, warns some more... Wood is extremely forgiving.

Metal cracks and lets go immediately, you're dead!

Homebuilt designs

There are a lot of homebuilts that can satisfy the requirement from the two seat EAA Acro II, the Pitts S2E, the Starduster II to many French designs like the very pleasant Piel Super Emeraude, aerobatic and efficient.
There's a Jurca Scirocco for sale locally here, it's a tandem two seat wooden aerobatic aircraft.

This one has a different engine to the normal one, and many have retractable undercarriage though fixed gear is normal:

If wood is so great, why dont they use more if it in the Pitts, or alike?

Or for that matter why dont they build modern airplanes out of wood?

I do agree that wood can be a great material, but there are far better materials to build airplanes from.

[Hedley]

there are far better materials to build airplanes from

Let me guess, you're a fashionable "composite kid"?

http://www.ntsb.gov/ntsb/brief.asp?ev_i ... 5209&key=1

NTSB Identification: ATL96FA051 .
The docket is stored in the Docket Management System (DMS). Please contact Records Management Division
14 CFR Part 91: General Aviation
Accident occurred Tuesday, February 20, 1996 in IMMOKALEE, FL
Probable Cause Approval Date: 10/4/1996
Aircraft: Sukhoi SU-31, registration: N31MX
Injuries: 1 Fatal.
The pilot was conducting a practice aerobatic flight, with two aerobatic pilots critiquing him from the ground. About ten minutes into the flight, the pilot initiated a pull toward the vertical with about 360 km/hr and 7 Gs, according to witnesses. This would have been well within the maximum airspeed and load specifications of 450 km/hr and 10 Gs, respectively. The right wing of the airplane separated during the pull up. The airplane entered a right roll and an uncontrolled descent, then it collided with the ground about 1 mile north of the airport. According to witnesses, the engine was developing power until impact, and the pilot did not announce any malfunctions or problems, prior to the wing failure. A postcrash ground fire consumed the fuselage. The unburned right wing was found about 3/4 mile east of the main wreckage. Testing of the wing spar was performed by the NTSB and MAK (Russian Investigative Authorities). Both agencies found numerous voids in the composite spar caps. The investigation revealed evidence that the curing process for the wing spar did not provide adequate vacuum pressure. There was evidence that during the curing process, the fibers separated from each other, which resulted in voids in the final composite material.

The National Transportation Safety Board determines the probable cause(s) of this accident as follows:

the manufacturer's improper composite curing process, which resulted in wing spar voids and subsequent failure of the wing during aerobatic flight.

Yeah, there's nothing like high tech!

Wood, metal and composite are all perfectly
good materials for aircraft structural construction,
if they are designed, built and maintained correctly.

[MichaelP]

The 'Grumman' AA1 Yankee was a Jim Bede design and has nothing in common with the RV series.
Spinning aside, the AA1 was a strong design, and it was originally a homebuilt!

As for the argument against the composite wing as illustrated by the Sukhoi 31 accident... That wing was not cured properly.
The same can be true of metal that has not been properly heat treated.
I once found an albeit minor component that was in the annealed condition in an Airbus 310 wing... That caused a stir!
But then I'd been a materials inspector in a previous time.

The Pitts has a steel tube fuselage, very rigid, great for crashing... But where you need the real strength is in the wing spars that have to tolerate the high stress loads and not fail suddenly, that's why most aerobatic biplanes have wood for this demanding task.

If Hedley really believed metal was better, he'd have a biplane with metal spars! How about an Andreason BA4?

As for unlimited aerobatic machines... The metal ones are the ones that broke as Neil William's Zlin 526 did... And remember the Zlin 50? That aeroplane had a life of 400 hours since the metal was expected to fatigue...

Wood never fatigues and is as good after many years as when it was new if it is looked after.
Even dried out WW1 spars were found to have retained a high precentage (80%?) of their original strength.

[Strega]

I never said that wood was not a good material, I simply stated there are better materials for building airplanes,

why dont they build modern high g aircraft such as the F-16 out of wood?

And all the BS of the suk with the poorly cured layups is just that BS,,

What happens if you use a substandard grade of wood in the spars on a pitts?

why dont they build helo rotors out of wood anymore?

And just FYI, all the loads in the spar on a Decathalon are carried by metal fixtures

The reason wood is used is because its cheap, easy to fabricate, and it is somewhat decent.

[Strega]

FYI

Event occurred Sunday, October 29, 1978 in WILSON, TX
Aircraft: MOONEY M18LA, registration: N4086
Injuries: 1 fatal
Commercial flight instructor, age 22, 566 total hours, 2 in type, instrument rated.
Time: 16:35
Damage: Destroyed
Departure point: Lubbock, TX
Intended Destination: Local
Type of Accident: Airframe failure
Phase of Operation: In flight acrobatics
Probable cause: Pilot exercised poor judgement. Wood in airframe and control surfaces was deteriorated, separated in flight. Acrobatics not authorized


Accident occurred MAY-10-84 at SUGAR LOAF KEY, FL
Aircraft: MOONEY M-18C, registration: N487M
Injuries: 1 Fatal
The aircraft was observed making several passes over a friends house. At the end of the third pass during, a climbing left turn, the right wing separated from the aircraft. Inspection of the wreckage revealed wood rot in the main wing spar. The last known inspection for wood and glue joint deterioration was performed in 1982 by the previous owner.

Probable Cause: Deterioration caused total wing separation
Contributing Factors: Improper maintenance and compliance with ADs by maintenance personnel


Accident occurred JUL-07-84 at NEW IBERIA, LA
Aircraft: MOONEY M-18LA, registration: N4090
Injuries: 1 Fatal.
A pilot witness observed the aircraft in a 20 to 30 degree dive at high speed just prior to the accident. He reported that at an altitude of about 1200 to 1300 ft, the aircraft began a pull-up. As the pull-up was started, the outboard portion of the aircraft's left wing folded upward & the aircraft entered an uncontrolled dive & crashed. The outboard 3 ft of the left wing was found relatively intact. The remainder of the wing was broken in numerous pieces. Also, the left aileron was bent upward about 3 ft from its outboard end. An exam of the wooden structure revealed discoloration in the fracture area. Evidence of wood deterioration & decay was found in localized areas around wing fasteners. A toxicological check of the pilot's blood showed some alcohol (0.04%); however, the pilot's body had not been immediately removed from the wreckage. The amount of alcohol due to putrefaction was not determined. The pilot's last medical certificate was dated 12/18/81.

Probable Cause: Wing, spar deteriorated
Maintenance inspection of aircraft inadequate.
Wing spar failure, total

[MichaelP]

Very good stats Strega, for the same aeroplane type, not approved for aerobatics, and clean enough to go through Vne very quickly.

I was once told the stats for the Cessna 210 were worse... Can you dig them up?

[Hedley]

Michael: your pathological dislike for metal construction
in aerobatic aircraft is a bit bizarre. Were you aware of
the event known as "World War Two" in which many, many
fully aerobatic fighter aircraft were constructed of metal.
Grumman and Republic both built many, many enormously
strong metal fighter aircraft.

After WWII, very few fighter aircraft were constructed
of wood. For example, in the "Korean War" both the
MiG-17 and F-86 were constructed of (gasp) metal.

In the "Vietnam War", I cannot recall a single wooden
fighter aircraft.

Etc.

Like I said before, all of wood, metal and composite
can either be very good or very bad choices for
structural use in aerobatic aircraft, depending upon
their design, construction and maintenance.

This really isn't very hard to understand.

[MichaelP]

Wood isn't good for high subsonic speeds and by the Korean conflict planes were faster... The Vampire still had a wooden fuselage at that time!

Probably one of the most beautiful aircraft built during WWII was a bomber that was faster than any fighter the Germans had, so fast that it was made into a fighter and fighter bomber as well.
It could fly high and fast and so was used for high level reconnaissance as well.

This aircraft was called a de Havilland Mosquito and it was made of wood.

There was a problem, a problem that still existed between British and North American built wooden aeroplanes when the Mooney Mite was being built... The glue used.

British Mosquitos were built with resin glues while Canadian Mosquitos were built with Casine glue.
Casine glue will not put up with the damp... Mosquitos were sent to the Far East to fight the Japanese.
Unfortunately these were Canadian built aeroplanes and they fell apart in the tropical damp.

If you build your wooden aeroplane, use resin glues.
I used to used Aerolite, and Aerodux glues and these were really good.

I love wooden aeroplanes, they are strong, they are easy to repair, and taken care of, they last a long time.
Avions Pierre Robin (APEX Aviation) in France build wooden aircraft developed from the Jodel series. These aircraft are extremely efficient for touring. Horsepower for horsepower they exceed the performance possible with metal construction in every respect.
Robin built metal aircraft as well, even very elegant ones like the Robin 3000, but they could never get the same amount of performance out of metal.

I am not against metal construction, I have flown enough aluminium aeroplanes in my time, but I have a lot more respect for well built wooden and composite aircraft.

It depends on what you know... North America is a place for cheap aeroplanes, built cheap, and not made to last.
There's no comparison between a French built Reims Cessna 172 and an American built one... The Americans do not know quality...

For real performance see: http://www.apex-aircraft.com/en/robin/index.htm and see what North American prejudice denies you.

[Hedley]

North America is a place for cheap aeroplanes, built cheap, and not made to last

Well, not entirely ... I might mention the Pitts, which is
designed and built in the USA, seems to last, and is
distinctly NOT inexpensive:



And then there is the Zivko Edge, built in Oklahoma,
which is tough as nails and not cheap either:

http://www.pelastamalmi.org/en/news/redbull0606.html

Note that one of Europe's finest aerobatic pilots,
Peter Besenyei (doubt you've ever heard of him)
chooses to fly an American-built Zivko. Hm.

Then there is the Lancair, in Oregon. Since it's
composite, I'm not sure it's built to last as long
as something with milk glue, but I sure wouldn't
kick it out of the hangar:

http://www.lancair.com/Main/evo.html

etc, etc.

Then there are USA military aircraft, which
are built to last much, much longer than
the disposable MiGs (for example). The
F-14, which saw service on salt-encrusted
aircraft carriers for decades, is by itself
a testimony to quality and durability. So
is the F-18.

Heck, an F-22 costs USD$250M. Is
that cheap?

[MichaelP]

I was at Dobbins when the second F22 was being assembled, it was like a scene out of Star Wars with this futuristic fighter taking shape.
A barrier of steel bars kept everyone at a distance... Secret stuff you know.
Then someone said it was the only aeroplane in the World capable of cruising at supersonic speeds for two hours... So I reminded him of Concorde which was in full service at that time... "It's the only other aircraft besides Concorde...." he went on.
I was at Dobbins for the C130J project, what a disaster that was! A Herc too far.

Cheap aeroplanes... I was more refering to the Cessna's and Pipers most people fly...
There are a few craftsmen built aeroplanes like Bellanca Vikings that break the mold...

As for the Pitt's... Compare it with a Swiss built Jungmann or Jungmeister... The Swiss workmanship is pure art and it's a real shame to put fabric on those wings.

[Hedley]

Then someone said it was the only aeroplane in the World capable of cruising at supersonic speeds for two hours... So I reminded him of Concorde which was in full service at that time... "It's the only other aircraft besides Concorde...." he went on.

IIRC Concorde required the use of four afterburning
engines to attain supersonic level flight. The claim to
fame of the F-22 is that unlike any other aircraft, it
does not need inefficient afterburners for supersonic.

Cheap aeroplanes... I was more refering to the Cessna's and Pipers most people fly...

Well, I doubt many people would call a new Cessna
or Piper "cheap" but Cessna and Piper deliver what
people want - characterless "spamcans" that are
easy to fly.

Most pilots cannot handle a tailwheel J-3 cub, remember!

[MichaelP]

Once at supersonic speed Concorde cruised without afterburners.

A friend of mine has a new Cessna 172 SP, and he is not impressed by the build quality for what he paid for it.

The CMFC bought two brand new Cessna 172s against the advice to buy DA40s... But there was a waiting list for DA40s while Cessna have aircraft in stock!

[Hedley]

A friend of mine has a new Cessna 172 SP, and he is not impressed by the build quality for what he paid for it.

The low volume and paperwork for certification really
bumps the price up. If they sold more, they could
amortize the fixed costs over more units.

IMHO if you're looking for "quality", you'd probably
be happier with a Beechcraft than a Cessna (think GM)
or Piper (think Ford). But a new Beechcraft doesn't
come cheap! Neither do Beechcraft parts!

[carholme]

MichaelP;

You are quite right about Concorde, and it could achieve supersonic by using re-heat to get through the high drag transonic range, then shutting down the heat and maintaining supercruise
It could also do it without reheat but the fuel consumption during this period was too high.

carholme

[200hr Wonder]

There are plenty of 30, 40 and 50 year old Cessna and Piper aircraft flying safely everyday, how many of the new DA40 will be around at that age?

**I have no idea about how the composites will react to ageing so this is a serious question. For example we had an old 172 leading edge come in contact with something a little strong and stiffer and put a hole just before the rib that was about six inches deep and four inches wide. Speed tape and a ferry permit to the AMO, a little new tin and she was back in flying shape in a matter of a couple days. How would a DA40 be to repair in the same instance?

[BoostedNihilist]

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[MichaelP]

There are plenty of 30, 40 and 50 year old Cessna and Piper aircraft flying safely everyday, how many of the new DA40 will be around at that age?

**I have no idea about how the composites will react to ageing so this is a serious question. For example we had an old 172 leading edge come in contact with something a little strong and stiffer and put a hole just before the rib that was about six inches deep and four inches wide. Speed tape and a ferry permit to the AMO, a little new tin and she was back in flying shape in a matter of a couple days. How would a DA40 be to repair in the same instance?

The Wassmer WA51A Pacific G AZYZ I flew back in the 70's was an older generation glass fibre aircraft. Very slick... It's still very slick and still flying as are many glassfibre sailplanes that pre date even this 1973 aeroplane.



Experience has shown that the bird comes off worse in a bird strike on a composite wing, yet the aluminium wing will suffer a dent and a skin repair is often required.
GFRP is extremely durable and resistent to damage.
It does have to be painted white though; the paint scheme should take UV into account.
But I have seen a lot of corroded aluminium in my time... There are a lot of aeroplanes on the Canadian register that can't be sold to the US or Europe because they are riddled with corrosion, yet they get signed off often by blind retired mechanics who do it for a few dollars.

There are probably more composite aeroplanes being built today than aluminium ones... Even the Boeing 787 has gone composite to a large extent.

[Hedley]

GFRP is extremely durable and resistent to damage

Really? I seem to remember fiberglas Corvette (cars)
that got tapped in a collision. The panel would "spider web"
as the cracks spread, and on more than one occasion,
the entire panel fell off as a results of the spreading cracks.

Not sure I'd want to make a structural part of an aircraft
with failure characteristics like that!

[MichaelP]

Corvette... You're writing about American quality again...
How about Lotus, they have a very good reputation, strong sports cars, come with four point harnesses, and are useless on Canadian roads... They need to be driven.

I am astonished by the fact that the Peltor headsets I really liked suddenly took a huge nose dive in quality... Then I learned the Pro GT headset is now made in the USA.
I have not faith in what the Mexicans build in the USA.

Another story...

Steve was/is a graduate aircraft engineer, pilot for BA, and avid Formula 1 racer.
He was also a member or the Tiger Club at Redhill when I knew him.
In the late 70's he designed and built a new glassfibre wing, tailplane, and elevator for his Cassutt racer.
People were questioning the strength of the structure and so he stood on one of the tailplanes. The fuselage twisted as his 170lbs or so was supported by the tailplane and then sprung back after he got off.
Being a BA 747 pilot, he took his Cassutt as personal baggage to LA, assembled it and took it to Reno for the formula one races.
Being British how could he expect to compete with the highly developed American aircraft?
But being British he was in it for the fun of it... He came 2nd over all, beating all but one of the American challengers.

Dictionary: Tailplane = Horizontal Stabilizer in American/Manifest Destiny Canadian.

Test: Stand on a Cessna tailplane and see the reaction....

[Hedley]

Ever wonder how many people a good ol' Texas Mooney can carry?



Legend has it that when Mooney was doing the
certification for their (gasp!) metal wing, they
cranked the G up, and the jig broke before the
wing did

[200hr Wonder]

Corvette... You're writing about American quality again...
How about Lotus, they have a very good reputation, strong sports cars, come with four point harnesses, and are useless on Canadian roads... They need to be driven.

I am astonished by the fact that the Peltor headsets I really liked suddenly took a huge nose dive in quality... Then I learned the Pro GT headset is now made in the USA.
I have not faith in what the Mexicans build in the USA.

Another story...

Steve was/is a graduate aircraft engineer, pilot for BA, and avid Formula 1 racer.
He was also a member or the Tiger Club at Redhill when I knew him.
In the late 70's he designed and built a new glassfibre wing, tailplane, and elevator for his Cassutt racer.
People were questioning the strength of the structure and so he stood on one of the tailplanes. The fuselage twisted as his 170lbs or so was supported by the tailplane and then sprung back after he got off.
Being a BA 747 pilot, he took his Cassutt as personal baggage to LA, assembled it and took it to Reno for the formula one races.
Being British how could he expect to compete with the highly developed American aircraft?
But being British he was in it for the fun of it... He came 2nd over all, beating all but one of the American challengers.

Dictionary: Tailplane = Horizontal Stabilizer in American/Manifest Destiny Canadian.

Test: Stand on a Cessna tailplane and see the reaction....

Fair enough Michael, I was not questioning the strength of fiberglass or other composites. That is a well documented fact and it can certainly be made strong enough for the application intended. What I was wondering is what happens with ageing? Certainly anything can rot if not taken care of even aluminium as you have point out. What needs to be done to keep these composite planes air worth over 50 years? The next question is what happens when the composite is locally stressed to destruction. For example a bird strike, running into something on the taxi way like a light standard and so forth. These are training planes these things will happen. Are more airframes going to end up in the scrap heap because the composite is not repairable or too expensive to repair? In the example I gave, what would ahve been the cost/down time for such a ding?

[Hedley]

IIRC the Cirrus has a 4,000 hour airframe
limit. God knows how you repair a ding
in the composite. I am doubtful as to how
many AMO's in Canada would be qualified
to do that.

[BoostedNihilist]

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[Hedley]

Ive found water in cruisers 4 feet above the waterline!!!! I believe the term is osmosis

http://en.wikipedia.org/wiki/Capillary_action