Spars

[waltermrich]

Re: Spars

When I rebuilt my spars I used my old factory spars for dimensions of over all length and placement of the strut fittings, I also purchased Terry's STC for wing modification for upgrading to an 85 HP engine which includes a drawing of the root fittings, I used the root wing attach fittings for exact placement on the spar for drilling the bolt holes, I used Douglas Fur for the spars and they are beautiful but slightly heavier. When I went to Oshkosh the year I was building my spars I asked the manager of Wag Aero how they got the drawings of the spars and he told me they have originals but were not willing to share them. Miguel live in a country where our regulations my not apply.

[skip]

Re: Spars

Working now to get the factory dimensions so we can maybe reproduce the original tooling (using factory data). If we can do that we should be able to drill pilot holes in a spar blank for the owner to finish ream all holes and add the doubles and finish. The tool should be allowable as "legal" to locate the holes for the owner and the owner can do the rest of the work to satisfy the Owner Produced Parts requirements.

Miguel may be stuck with making another tool (kind of expensive to ship the tool or spars that far compared to making another tool) but at least if anyone else down there needed a spar teh tool would already exist fairly close by.

Hank

When I did my spars I probably agonized over drilling the root fitting holes for the phenolic bushings most of all. In the end They lined up and the bolts all slid through with a satisfying pressure. But If I had to do it over again, I have often thought that a jig like Robert Lees describes on his web pages
http://www.taylorcraft.org.uk/Brey_r...structural.htm
would have saved time in the long run and gotten rid of a lot of the pucker factor each time the drill press ran the bit down into the spar blank.

It never fails to amaze me how often a bunch of "extra" "wasted time" spent on making proper jigs and fixtures results in a better product in a shorter time.

[Guest]

Re: Spars

When I rebuilt my spars I used my old factory spars for dimensions of over all length and placement of the strut fittings, I also purchased Terry's STC for wing modification for upgrading to an 85 HP engine which includes a drawing of the root fittings, I used the root wing attach fittings for exact placement on the spar for drilling the bolt holes, I used Douglas Fur for the spars and they are beautiful but slightly heavier. When I went to Oshkosh the year I was building my spars I asked the manager of Wag Aero how they got the drawings of the spars and he told me they have originals but were not willing to share them. Miguel live in a country where our regulations my not apply.

Makes perfect sense.

After investing in the drawings and tooling and some stock of spars why would they give away the means to cut themselves out of the business?

They probably do have originals but I wonder how they obtained them??

[Guest]

Re: Spars

Here's a thought.

If you were considering investing your money into say reviving the Taylorcraft company.

Would you be enthusiastic to invest and produce lots of service parts for Taylorcraft airplanes?

Or would you think about loosing your shirt because they might not sell?

Dave

[waltermrich]

Re: Spars

Good point, It would be ideal if some how the spar drawings were to appear on the Forum technical documents, but that might be wishing for a lot.

[N96337]

Re: Spars

For crying out loud, this isn't rocket science guys!!! Take the spar, get your tape measure out and measure thickness as well as length and height, then measure from the butt and set up "stations". This will give the distance from the butt. Where there is a hole, measure up from the bottom of the spar to the center of the hole. If you're worried about being at the exact center of the hole, measure to the inboard or bottom edge of the hole, and ADD half the diameter of the hole. This has been done for years and years by many mechanics. Use AC43.13 as well as ANC-19, AC23-27 and any others you think we need. All approved/acceptable data. We've beat the "owner produced parts" to death. I've not heard of anyone being fined or being hassled for producing parts for any aircraft of this vintage. As far as Forrest finding a drawing and providing it, I'm not gonna hold my breath....we've been down that road before. I've got a set of front and rear spars from my Tcraft, hanging in the rafters, as do a few others on here. Let's pull them down and measure like I described above. They don't need to dry or be at a like moisture content....it's not going to make a noticeable difference..... Then we can post them here and get this guy some dimensions that he (as well as the rest of us) can work with. No hassle, no waiting, no big deal. Spars have been replaced as long as airplanes have been flown.
John

[Guest]

Re: Spars

For crying out loud, this isn't rocket science guys!!! Take the spar, get your tape measure out and measure thickness as well as length and height, then measure from the butt and set up "stations". This will give the distance from the butt. Where there is a hole, measure up from the bottom of the spar to the center of the hole. If you're worried about being at the exact center of the hole, measure to the inboard or bottom edge of the hole, and ADD half the diameter of the hole. This has been done for years and years by many mechanics. Use AC43.13 as well as ANC-19, AC23-27 and any others you think we need. All approved/acceptable data. We've beat the "owner produced parts" to death. I've not heard of anyone being fined or being hassled for producing parts for any aircraft of this vintage. As far as Forrest finding a drawing and providing it, I'm not gonna hold my breath....we've been down that road before. I've got a set of front and rear spars from my Tcraft, hanging in the rafters, as do a few others on here. Let's pull them down and measure like I described above. They don't need to dry or be at a like moisture content....it's not going to make a noticeable difference..... Then we can post them here and get this guy some dimensions that he (as well as the rest of us) can work with. No hassle, no waiting, no big deal. Spars have been replaced as long as airplanes have been flown.
John

John,

No disputes with anything that you said.

I am not willing to invest the time to measure and record the info.

Too much of my time for someone to avoid buying parts that are available for purchase. Just shifting the cost from one guy to another.

Go buy the parts is my best answer. Shipping will be high for spar stock as well as finished spars.

Sorry, Dave.

[Guest]

Re: Spars

Good point, It would be ideal if some how the spar drawings were to appear on the Forum technical documents, but that might be wishing for a lot.

Walter,

I had a good laugh at myself about this.

I was attempting to make the point that we should buy parts from those that are willing to supply them.

However I see that I actually may have made the counterpoint - that this is just not a viable parts business and therefore we need drawings!

Personally I would rater buy from those that will supply but I see your point.

Dave

[Hank Jarrett]

Re: Spars

As with the glove box door discussion, if I can BUY the part for anything near reasonable, I will BUY IT. In this case, Miguel is not really in a position to have something like new spars shipped all the way to him. If it comes down to it, I will measure my spars and sent the info, but I am still willing to believe in Forrest.

Hank

[Guest]

Re: Spars

As with the glove box door discussion, if I can BUY the part for anything near reasonable, I will BUY IT. In this case, Miguel is not really in a position to have something like new spars shipped all the way to him. If it comes down to it, I will measure my spars and sent the info, but I am still willing to believe in Forrest.

Hank

How will the wood be brought in? That will be shipped won't it? Are they growing spruce and fir Uruguay? or does it come from the NW corner of the US?

[Mark Bowden]

Re: Spars

Hi,
If you purchase a spar from the USA for import to Uruguay, there may be another challenge with both exporting and importing a hardwood product. Most countries require treatment for bugs on hardwood that is exported or imported. This process is heat treatment and application of methyl bromide.

Kiln drying may satisfy the heat treatment requirement but often it doesn’t get hot enough. 56 deg C is required. This service treatment is fairly easy to find for shipping materials. Once treated a treatment stamp must be applied. https://en.wikipedia.org/wiki/ISPM_15

On “sold” hardwood goods the treatment paper work is a minimum requirement for export/import. For shipping crate materials the stamp is a minimum requirement to clear customs. Note, plywood is exempt. The lamination and curing process makes it ok. The USDA does inspections in the USA on export products.

You would have to check with the companies that make the spars in the USA to see what export/import requirements would apply to the hardwood product itself. It depends on what the trade agreements are between the countries, it isn’t hard to find out.

Without the stamp or paperwork it will get stopped at customs, quarantined, returned or destroyed!

To get to the goal of new spars, buying Spruce or Fir from an importer in Uruguay and making them as an owner produced part may be easier than buying from a supplier in the USA who doesn't export as a standard practice.

[Guest]

Re: Spars

Mark,

Thanks, that is interesting.

Spars and spar stock will be soft fir or spruce most likely. Do you think that will get more or less scrutiny than hardwood?

So you are also saying that since there may be experienced spruce and fir importers that it may be more likely that importing spar blanks and drilling them in country than finding a U.S. spar manufacturer that is prepared to handle the export details. Did I get it?

Dave

p.s. I missed that ISPM 15 applies to the crate not the product so I suppose my question about softwoods is moot.

[PA1195]

Re: Spars

Why not find some company/industry/method that offers 3-D laser scanning and run a spar, or part, through their machine? I assume (ignorance does have its bennies) there's a 2 or 3-axis XYZ output of some form that can be converted to repeatable dimensions in software? Cut the dupe with a CNC or whatever machine.

Examples of possibility:

http://polhemus.com/scanning-digitizing/overview/

http://thewoodportal.com/articles/an-introduction-to-3d-laser-scanning-for-woodworking/

http://www.woodbusiness.ca/sawmilling/scanning-and-optimization-for-the-planer-mill

Or pressure trace a spar with stable material, roll it up, and mail it. Just some thoughts. Not my profession.

Gary

[Hank Jarrett]

Re: Spars

We had a machine like what you are talking about called a "Cardex" when I worked for the Navy on the A-6. We used it to input all the data needed for a CNC machine to duplicate just about anything. NOT a cheap machine and I don't have access to one any more (not that my rich Uncle would have ever let me do my own project on it when I DID have access!)

Once we have the drawings and can see the tolerances making a drawing will be pretty easy (if those tolerances aren't too tight). Wouldn't the tolerances for the tandem bird spars be the same as the side by side ones? Anyone have the drawings for any of the other planes?

Hank

Forrest used to say most parts of a "T" were + or - 1/8". If that is true of spars I can measure that on my spars with a steel ruler. Somehow I think the hole spacing is a "bit" tighter on the spars.

[astjp2]

Re: Spars

Sitka spruce is not a hardwood or exotic and they need to have at least 1 coat of varnish before being shipped, that is some weird rule about invasive species. Tim