Strut angle conundrum

[Guest]

I think about the front strut angle issue once in a while and it just never makes sense to me.

The actual angle between the surface of the front strut attach fitting at the longeron and the surface of the front strut attach fitting at the spar should be the same for all airplanes (within some small tolerance).

So if you believe what I just said then there should only be one front strut design that fits all planes.

Of course if that was true then Alaska airfames would only be selling one of their strut designs. But they apparently actually sell both.

At one moment I wondered if the angle problem was mere illusion caused by using wider streamline tubing and not placing the fiitings at each end the same distance back from the leading edge (i.e. the same distance from the center of the width). That would cause an apparant angular difference but not by more than about 2" over about 10' or about 1 degree. So that does not explain a 6 degree difference.

Curious I went down to where I have about 6 old front struts and measured the angle between the front surface where it bolts to the wing fitting of the spar end of the front strut and the strut leading edge.

It varied from 2.x degrees to 6.x degrees.

Damaged struts being the higher numbers.

I am not sure what it all means, I am capable of making some guesses.

[Robert Lees]

Re: Strut angle conundrum

TCDS for all Taylorcraft (from A to F is 1 (one) degree dihedral.

Hope that helps.

[PA1195]

Re: Strut angle conundrum

"I am nit sure what it all means, I am capable of making some guesses"

Don't keep us in suspense

GAry

[M Towsley]

Re: Strut angle conundrum

David,

When I had my struts off the airplane I noted that neither strut had the same angle,

I figured if I ever decide to get new struts I am going to have to send the old ones off to the manufacturer so I get exactly what I need. I wished I had taken a picture, I don't think you are seeing an illusion.

[Nefj40]

Re: Strut angle conundrum

Since my struts are do after the first of the year, I've spent the last six months bouncing back and forth on what I was going to do. I noticed a week ago that AA has 10% off until the end of the year so I decided to just go with their struts. After reading up on their site on how to measure the angle, I measured mine a couple days ago and came up with 10* on both sides!?? I'm heading into town this morning and might even go up for a little bit so I'm going to measure again. I noticed on the order page there was 2*, 8* and (call me) options.

Wing sweep make a difference?

[Guest]

Re: Strut angle conundrum

Since my struts are do after the first of the year, I've spent the last six months bouncing back and forth on what I was going to do. I noticed a week ago that AA has 10% off until the end of the year so I decided to just go with their struts. After reading up on their site on how to measure the angle, I measured mine a couple days ago and came up with 10* on both sides!?? I'm heading into town this morning and might even go up for a little bit so I'm going to measure again. I noticed on the order page there was 2*, 8* and (call me) options.


Wing sweep make a difference?

Hi Dave,

There is no wing sweep.

Dave R.

[Nefj40]

Re: Strut angle conundrum

Hi Dave,

There is no wing sweep.

Dave R.

When I put my VGs on last winter it sure looked like there was a tiny bit of forward sweep. Probably an optical illusion.

[Nefj40]

Re: Strut angle conundrum

Tail up and level, my wings are definitely swept back. Somewhere around 1.25 inches. I'd post a picture if I knew how to.

[LostnSpace]

Re: Strut angle conundrum

TCDS for all Taylorcraft (from A to F is 1 (one) degree dihedral.

Hope that helps.

Maybe I am missing something, but how does dihedral have anything to do with strut angle fore and aft, just asking, gary

[PA1195]

Re: Strut angle conundrum

To measure the upper strut angle on the plane I'd be tempted to take good pictures from below, then print them and overlay a graph to determine a relative angle at home. If present the GW increase reinforcement plate on the spar bracket may confuse some but a centerline drawn over it should offer a reference.

I'll try this in the next few days just for fun.

To post a picture hit Go Advanced, Attachments-Manage Attachments, Upload files-choose file-upload, mine are on my Apple desktop but select where and what. Size is limited as noted in the Attachment Key at the bottom of the Attachment deal.

Gary

[Nefj40]

Re: Strut angle conundrum

I found a different protractor and came up with 8*, the other angle finder I used was too big to try and use on mounted struts.

It's a crappy pic but you get the idea. Thanks for the picture tip.

[PA1195]

Re: Strut angle conundrum

There's a set of sealed struts on Barnstormers listed 11/11/16.

Gary

[Guest]

Re: Strut angle conundrum

Maybe I am missing something, but how does dihedral have anything to do with strut angle fore and aft, just asking, gary

I think that you are correct as long as hinge line for the left wing and right wing are parallel in the vertical (fore & aft) an horizontal planes and I think that should be true for these planes.

In other words if you put a rod thru the wing attach fitting then the rods will be parallel in the horz. an vertical (fore & aft).

[Guest]

Re: Strut angle conundrum

I found a different protractor and came up with 8*, the other angle finder I used was too big to try and use on mounted struts.

It's a crappy pic but you get the idea. Thanks for the picture tip.

Thanks for the picture.

Couple of thoughts come to mind.

1) We assume that when the tail is level that the wing cord is also level, that is probably not true there is probably a couple degrees diff but I doubt that is the source of the issue at hand.

2) I have been confused before by dihedral and chord angle.

3) The string is interesting. I think that before I believed in sweep back I would redo the string measurement and use a technique that only allows the string to make contact at the wing tips. Perhaps tape a block of wood to the last rib at a certain distance aft of the leading edge then see if the string is parallel to the leading edge. It looks like the existing string is touching in many places, that is why I said what I just said.

4) It is possible that some planes have a small sweep back (or ahead) due to repairs or factory issues.

5) 1.25" sweep over the lenght of the wing is about .5 degrees

Dave R

[Nefj40]

Re: Strut angle conundrum

I definitely agree on using blocks and a couple more sets of hands even just to be a little more accurate. You bringing this 2*/8* difference up right now piqued my interest a little since I'm getting ready to order struts.