Fairchild Club Forum

Posted: **Sat Jan 19, 2008 3:48 pm**

'Other than the Weatherly which used the PT-19 fuselage frame, there are no wood parts of the airplane that can be replaced with aluminum, mainly for the reasons Mark stated.

I'll add my 5 cents (inflation, you know).

1) It's not worth it.
2) Design, materials and stress engineering will be too expensive.
3) The FAA will not approve it
4) Not only would you have to build aluminum wings, you also need an aluminum center section to distribute the flight loads.
5) Not enough buyers willing to cough up the thousands required to buy the STC (even if you could get one)
6) Experimental is not the way to go, you need a legitimate test program to fly the airplane with the metal wings so you need to hire a qualified engineering test pilot.
5) Did I say it's not worth it?

Believe it or not, if you built model airplanes, you could build PT-19 wooden structures using FAA approved materials, techniques and a little bit of knowhow. There's plenty of information available in the airplane tech manuals and AC43-13-1B to do the job. And all it takes for that is a FAA Form 337 Major Repair document to be filed when you're done.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

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Posted: **Sat Jan 19, 2008 5:08 pm**

'Actually Mike, it can be done without having to hire an experimental test
pilot. The FAA will approve the mod. The biggest problem is that by the time
you meet all the engineering requirements and test requirements to satisfy
the FAA, you will have expended well over a half million dollars. It could
be done and moved into the experimental, amatuer built catagory but you
would have to get a ruling on the 51% rule first.

Craig C.

[Non-text portions of this message have been removed]'

Posted: **Sat Jan 19, 2008 9:13 pm**

'I agree with most you say, but cannot understand your reasoning for number 4.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@yahoogroups.com
Sent: Saturday, January 19, 2008 4:48 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Other than the Weatherly which used the PT-19 fuselage frame, there are no wood parts of the airplane that can be replaced with aluminum, mainly for the reasons Mark stated.

I'll add my 5 cents (inflation, you know).

1) It's not worth it.
2) Design, materials and stress engineering will be too expensive.
3) The FAA will not approve it
4) Not only would you have to build aluminum wings, you also need an aluminum center section to distribute the flight loads.
5) Not enough buyers willing to cough up the thousands required to buy the STC (even if you could get one)
6) Experimental is not the way to go, you need a legitimate test program to fly the airplane with the metal wings so you need to hire a qualified engineering test pilot.
5) Did I say it's not worth it?

Believe it or not, if you built model airplanes, you could build PT-19 wooden structures using FAA approved materials, techniques and a little bit of knowhow. There's plenty of information available in the airplane tech manuals and AC43-13-1B to do the job. And all it takes for that is a FAA Form 337 Major Repair document to be filed when you're done.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

__________________________________________________________
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Posted: **Sun Jan 20, 2008 8:50 am**

'If you want to see what the aluminum wing and center section look like a club member in Athol, Idaho has one flying.

John Berendt
Fairchild Club

----- Original Message -----
From: rernest151
To: fairchildclub@yahoogroups.com
Sent: Saturday, January 19, 2008 12:36 PM
Subject: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

--- In fairchildclub@yahoogroups.com, "rernest151" wrote:
>
> I was wondering if anyone has designed or built an aluminum wing for
> the PT-19 in the decades since WW2, would anyone be interested?
>
Just a thought, it might be a way to save some of the planes that have
been grounded for problems with the wing, I've seen a PT-19 wing being
restored, beautiful woodwork but a lot more actual work than building
an aluminum wing.

[Non-text portions of this message have been removed]

'

Posted: **Sun Jan 20, 2008 10:32 am**

'Are there any pictures?

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: fchld
To: fairchildclub@yahoogroups.com
Sent: Sunday, January 20, 2008 10:42:02 AM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

If you want to see what the aluminum wing and center section look like a club member in Athol, Idaho has one flying.

John Berendt
Fairchild Club

----- Original Message -----
From: rernest151
To: fairchildclub@ yahoogroups. com
Sent: Saturday, January 19, 2008 12:36 PM
Subject: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

--- In fairchildclub@ yahoogroups. com, "rernest151" wrote:
>
> I was wondering if anyone has designed or built an aluminum wing for
> the PT-19 in the decades since WW2, would anyone be interested?
>
Just a thought, it might be a way to save some of the planes that have
been grounded for problems with the wing, I've seen a PT-19 wing being
restored, beautiful woodwork but a lot more actual work than building
an aluminum wing.

[Non-text portions of this message have been removed]

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'

Posted: **Sun Jan 20, 2008 10:52 am**

'The 51% rule applies only to the experimental/amateur built category. It does not apply to airplanes holding a normal category airworthiness certificate. It cannot be flown except as a developmental flight test aircraft which limits it to specific flight operations and flight test areas. Check out FAR Part 21 which outlines the issuance of airworthiness certificates. It is also a Major Alteration which outlines "That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or that is not done according to accepted practices or cannot be done by elementary operations" (FAR Part 1).

It's still not worth it.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: "cvcantwell@charter.net"
To: fairchildclub@yahoogroups.com
Sent: Saturday, January 19, 2008 6:11:24 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Actually Mike, it can be done without having to hire an experimental test
pilot. The FAA will approve the mod. The biggest problem is that by the time
you meet all the engineering requirements and test requirements to satisfy
the FAA, you will have expended well over a half million dollars. It could
be done and moved into the experimental, amatuer built catagory but you
would have to get a ruling on the 51% rule first.

Craig C.

[Non-text portions of this message have been removed]

____________________________________________________________________________________
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Posted: **Sun Jan 20, 2008 11:02 am**

'The strain modulus of wood vs. metal are very different where you may need to reinforce specific areas of the structures to spread the flight loads.
Young's Modulus rates wood at 1,300,000 to 1,600,000 PSI where aluminum is rated at 10,000,000 PSI. So, it is possible to tear the metal wings off of a wood center section by applying certain flight loads.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: david stroud
To: fairchildclub@yahoogroups.com
Sent: Saturday, January 19, 2008 9:40:02 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

I agree with most you say, but cannot understand your reasoning for number 4.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@ yahoogroups. com
Sent: Saturday, January 19, 2008 4:48 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Other than the Weatherly which used the PT-19 fuselage frame, there are no wood parts of the airplane that can be replaced with aluminum, mainly for the reasons Mark stated.

I'll add my 5 cents (inflation, you know).

1) It's not worth it.
2) Design, materials and stress engineering will be too expensive.
3) The FAA will not approve it
4) Not only would you have to build aluminum wings, you also need an aluminum center section to distribute the flight loads.
5) Not enough buyers willing to cough up the thousands required to buy the STC (even if you could get one)
6) Experimental is not the way to go, you need a legitimate test program to fly the airplane with the metal wings so you need to hire a qualified engineering test pilot.
5) Did I say it's not worth it?

Believe it or not, if you built model airplanes, you could build PT-19 wooden structures using FAA approved materials, techniques and a little bit of knowhow. There's plenty of information available in the airplane tech manuals and AC43-13-1B to do the job. And all it takes for that is a FAA Form 337 Major Repair document to be filed when you're done.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

____________ _________ _________ _________ _________ _________ _
Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

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Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.7/1232 - Release Date: 1/18/08 7:32 PM

[Non-text portions of this message have been removed]

____________________________________________________________________________________
Never miss a thing. Make Yahoo your home page.
http://www.yahoo.com/r/hs

[Non-text portions of this message have been removed]

'

Posted: **Sun Jan 20, 2008 11:43 am**

'Mike, It can be done. It takes talking to the feds and showing that you will
in fact producing over 51% of the work involved in producing the end
product. You then have to document that work. I can guarantee that designing
an entirely new wing and center section, producing the parts and completing
the fabrication will take the average builder more time than building a
complete, direct copy of a PT from scratch.

There are several homebuilts that utilize major componets of production
aircraft. A couple that I can think of right off the bat...V6 STOL, either
the Kingfisher or VJ-22. The thing is that it can no longer be considered a
PT or M-62. Part of the process would be deregistering the original a/c and
surrender of the CofA. At that point, as far as the feds were concerned, it
would no longer exsist. There have already been rulings by the feds on this
type work. There were several attempts to take production aircraft and
re-engine them with non-standard powerplants. The feds ruled that simply
re-engineering the firewall forward was not sufficient work to consider the
aircraft as presented, to be elegible under the rules as written for E.A..
The converters were forced to go with moving to the flight research
classification and having to produce data. It also effectively killed the
usefullness of the aircraft by all of the flight rule limitations that were
imposed.
We have dealt with this at work for a number of years now. Just to really
shake things up, the YF-22¹s and 23¹s were flown under Experimental,
Amatuer built due to contractural requirements despite being factory built.

It¹s moot point anyway, as the return for the cost input makes it
economically a dead idea.

[Non-text portions of this message have been removed]'

Posted: **Sun Jan 20, 2008 2:22 pm**

'Please don't think I'm trying to be argumentative, I'm just trying to understand.

Let's assume the entire aircraft was designed to withstand 6 g's with it's wood on wood
wing components. Then, if a wood center section plus a wood wing on the PT can take
6 g's before failure, can I assume that a combination of a wood center section plus a metal
wing designed for 6 g's could also take 6 g's ? So, if the entire airframe was designed
for that basic 6 g's, how does making the wing component capable of something in excess
of 6 g's contribute to possible failure ? I'm just thinking that if + 6 g's will do that, then + 6 g's
would do it to a complete wood structure anyway.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@yahoogroups.com
Sent: Sunday, January 20, 2008 12:02 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

The strain modulus of wood vs. metal are very different where you may need to reinforce specific areas of the structures to spread the flight loads.
Young's Modulus rates wood at 1,300,000 to 1,600,000 PSI where aluminum is rated at 10,000,000 PSI. So, it is possible to tear the metal wings off of a wood center section by applying certain flight loads.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: david stroud
To: fairchildclub@yahoogroups.com
Sent: Saturday, January 19, 2008 9:40:02 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

I agree with most you say, but cannot understand your reasoning for number 4.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@ yahoogroups. com
Sent: Saturday, January 19, 2008 4:48 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Other than the Weatherly which used the PT-19 fuselage frame, there are no wood parts of the airplane that can be replaced with aluminum, mainly for the reasons Mark stated.

I'll add my 5 cents (inflation, you know).

1) It's not worth it.
2) Design, materials and stress engineering will be too expensive.
3) The FAA will not approve it
4) Not only would you have to build aluminum wings, you also need an aluminum center section to distribute the flight loads.
5) Not enough buyers willing to cough up the thousands required to buy the STC (even if you could get one)
6) Experimental is not the way to go, you need a legitimate test program to fly the airplane with the metal wings so you need to hire a qualified engineering test pilot.
5) Did I say it's not worth it?

Believe it or not, if you built model airplanes, you could build PT-19 wooden structures using FAA approved materials, techniques and a little bit of knowhow. There's plenty of information available in the airplane tech manuals and AC43-13-1B to do the job. And all it takes for that is a FAA Form 337 Major Repair document to be filed when you're done.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

____________ _________ _________ _________ _________ _________ _
Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

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Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.7/1232 - Release Date: 1/18/08 7:32 PM

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__________________________________________________________
Never miss a thing. Make Yahoo your home page.
http://www.yahoo.com/r/hs

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'

Posted: **Sun Jan 20, 2008 6:31 pm**

'Right David, you would have to design the structure to assume that the 6G loads would equalize throughout the structure. Since the fuselage frame attaches to the center section, it is not a factor. Most structures are designed to a factor of stress, say for the purpose of this discussion that it is 1.5 times the load to be imposed. The wing and center section are the parts that must be designed correctly to assume the 6G load and the modulus of strain of the dissimilar materials needs to be a consideration. So, the structures must be calculated to a 9G load in order to safely take the 6G's. I'm not a stress guy by any means but my job involves contact with design and stress engineers so I've learned a few things from them.

Getting back to the original question of replacement bolt on metal wings for the PT series airplanes, there are none and it is financially unfeasible to go through the effort for so few airframes out there.

Craig commented on the 51% rule and is correct in that you can use the airframe parts to assemble and aircraft but you cannot call it a M-62 series airplane.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: david stroud
To: fairchildclub@yahoogroups.com
Sent: Sunday, January 20, 2008 3:24:15 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Please don't think I'm trying to be argumentative, I'm just trying to understand.

Let's assume the entire aircraft was designed to withstand 6 g's with it's wood on wood
wing components. Then, if a wood center section plus a wood wing on the PT can take
6 g's before failure, can I assume that a combination of a wood center section plus a metal
wing designed for 6 g's could also take 6 g's ? So, if the entire airframe was designed
for that basic 6 g's, how does making the wing component capable of something in excess
of 6 g's contribute to possible failure ? I'm just thinking that if + 6 g's will do that, then + 6 g's
would do it to a complete wood structure anyway.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@ yahoogroups. com
Sent: Sunday, January 20, 2008 12:02 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

The strain modulus of wood vs. metal are very different where you may need to reinforce specific areas of the structures to spread the flight loads.
Young's Modulus rates wood at 1,300,000 to 1,600,000 PSI where aluminum is rated at 10,000,000 PSI. So, it is possible to tear the metal wings off of a wood center section by applying certain flight loads.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

----- Original Message ----
From: david stroud
To: fairchildclub@ yahoogroups. com
Sent: Saturday, January 19, 2008 9:40:02 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

I agree with most you say, but cannot understand your reasoning for number 4.

David Stroud Ottawa, Canada
C-FDWS Christavia
Fairchild 51 under construction

----- Original Message -----
From: Michael Denest
To: fairchildclub@ yahoogroups. com
Sent: Saturday, January 19, 2008 4:48 PM
Subject: Re: [fairchildclub] Re: Has anyone ever designed or built an aluminum wing for the PT series?

Other than the Weatherly which used the PT-19 fuselage frame, there are no wood parts of the airplane that can be replaced with aluminum, mainly for the reasons Mark stated.

I'll add my 5 cents (inflation, you know).

1) It's not worth it.
2) Design, materials and stress engineering will be too expensive.
3) The FAA will not approve it
4) Not only would you have to build aluminum wings, you also need an aluminum center section to distribute the flight loads.
5) Not enough buyers willing to cough up the thousands required to buy the STC (even if you could get one)
6) Experimental is not the way to go, you need a legitimate test program to fly the airplane with the metal wings so you need to hire a qualified engineering test pilot.
5) Did I say it's not worth it?

Believe it or not, if you built model airplanes, you could build PT-19 wooden structures using FAA approved materials, techniques and a little bit of knowhow. There's plenty of information available in the airplane tech manuals and AC43-13-1B to do the job. And all it takes for that is a FAA Form 337 Major Repair document to be filed when you're done.

Mike

Quando omni flunkus moritati
(If all else fails, play dead)
- "Red" Green

____________ _________ _________ _________ _________ _________ _
Be a better friend, newshound, and
know-it-all with Yahoo! Mobile. Try it now. http://mobile. yahoo.com/ ;_ylt=Ahu06i62sR 8HDtDypao8Wcj9tA cJ

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Checked by AVG Free Edition.
Version: 7.5.516 / Virus Database: 269.19.7/1232 - Release Date: 1/18/08 7:32 PM

[Non-text portions of this message have been removed]

____________ _________ _________ _________ _________ _________ _
Never miss a thing. Make Yahoo your home page.
http://www.yahoo. com/r/hs

[Non-text portions of this message have been removed]

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Checked by AVG Free Edition.
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