Wing leveling

[jmvolpp]

We put the freshly inspected (3rd time) wing struts back on N44305 this morning and this time decided to include the prescribed wing leveling procedure, not having done so previously. We replaced the adjustment plugs as they had been the first 2 times (shortest strut possible) and found the reference measurement to be 3" on both sides, so we backed the plugs out to the longest strut possible position and found the measurement to be 1 9/16" on one side and 1 3/4" on the other - I have yet to flight test this change. What with the string level across the wings and the presence of rib stitches at the point of contact between the level and the underside of the wing, there seems to be plenty of opportunity to introduce some variation in the end result. Have other members of the tribe had similar experience?

Mike V.

[Guest]

Re: Wing leveling

Hi Mike,

I am not sure that I am following your description.

Are you saying that when you unscrew the rear strut plugs all the way out that the wash out dimension can only reduce to 1-9/16" on one side and 1-3/4" (goal is 1-5/16" correct?) on the other and when the plugs are all the way in the measurement is 3" on both sides? Is that it?

What is the string about?

Why did you replace the plugs? I don't follow.

Dave

[jmvolpp]

Re: Wing leveling

Correct on the measurements.

String is stretched from wingtip to wingtip at the level of the front spar with string level in the middle.

Plugs were removed to apply LPS3.

I was surprised that moving the adjustment plugs from one extreme to the other didn't result in having the desired result somewhere in between. Today I plan to review the whole procedure and recheck the measurements before blasting off into the wild blue.

Mike V.

[3Dreaming]

Re: Wing leveling

You need to find the Taylorcraft procedure for setting the wash out, and set it before you go fly.

[Guest]

Re: Wing leveling

Correct on the measurements.

String is stretched from wingtip to wingtip at the level of the front spar with string level in the middle.

Plugs were removed to apply LPS3.

I was surprised that moving the adjustment plugs from one extreme to the other didn't result in having the desired result somewhere in between. Today I plan to review the whole procedure and recheck the measurements before blasting off into the wild blue.

Mike V.

Mike,

I suggest using anti-seize compound on the plug threads. Its a silver paste made of molybdenum disulfide (I think), its a silver paste that you can buy in an $8 jar or a $2 packet at an auto store.

Based on your response to my inquiry I think that you already have the Taylorcraft drawing with the "30" level", am I correct?

If you don't have I can scan and post a copy.

Dave

[Dick Smith]

Re: Wing leveling

You may have this info already, but if not...these 2 links have the basic instructions buried down in the text.

http://www.taylorcraft.org/docs/taylorcraft%20owners%20manual%20BB12.pdf

http://www.airframesalaska.com/v/vspfiles/pdf/Tcaftinstall.pdf

[PA1195]

Re: Wing leveling

Some of this was discussed here: http://vb.taylorcraft.org/showthread...t=wing+washout My comments and measurements are in posts #30, 32, and 34.

I believe the problem with doing what Taylorcraft suggests without further examination is that it's based upon the assumption that all the associated parts of the wings and fuselage meet design criteria. Over the years the parts can be changed, exchanged, and damage to the wings and fuselage occurs. It may no longer meet the design or even the initial as-built specs for that plane

All it takes is for the tail to no longer be the level source, the wing root incidence to be otherwise, or the ribs no longer in the correct position on the spar or even deformed. Then that 1 5/16" no longer reflects the true wash.

Setting the differential wash from inboard to outboard wing (per my experience described in the posts above) was my only option. My next step will be to measure the dihedral of the front and rear spars and link that to a value for washout. My struts are new Airframes parts, the dihedral is 1.5* for each wing measured with an accurate digital level, and the rear struts are set at 1 turn in from maximum extension. Ball's in the middle, ailerons level, stall benign and equal on both wings.

Gary

[jmvolpp]

Re: Wing leveling

Thanks, guys, for reference to past threads - plenty of ways to skin the cat.

Dave, I'm also an anti-seize fan, however in this case, deferred to the abundance of LPS3 coating everything!

We think we improved the accuracy of our measurements some today, but results pretty much the same, so we shortened the left strut a turn and a half to match the right at 1 3/4". The midday air around MIE was pretty lively, but straight and level flight test was uneventful with no wing heaviness. When conditions are a bit better, will explore stalls and spins.

Mike V.

[PA1195]

Re: Wing leveling

Basically what my link above to the previous thread means is: Initial measurements on any wing at both the root and tip rib should result in the distance from the level to the wing at the tip being about 1/2" less for about 1* of wash, 3/4" for 1.5*, etc. Takeoff and note if one wing initially lifts before the other, and fly then adjust for stall behavior and wing heaviness.

Alternatively set both wing strut adjustment screws the same (threaded one turn from all the way out in my case) and go fly. That's what we did regardless of the overall washout within and between wings.

Gary

[astjp2]

Re: Wing leveling

Don't over analyze it. Get it close and fly it to get the fine adjustments. Tim

[jmvolpp]

Re: Wing leveling

Today afforded the opportunity to further flight test following the strut adjustments. Straight ahead power off, accelerated (actually 1000 rpm to preclude engine stopping), and full power departure stalls were uneventful, wanting to fall off on left wing only during straight ahead stall. That tendency made for pleasantly busy "falling leaf" stalls; left and right 1 turn spins were normal, maybe requiring a little more forward stick at recovery than usual. Thankfully those old engineers made these birds stable throughout the range of adjustment.

Mike V.

[PA1195]

Re: Wing leveling

Today afforded the opportunity to further flight test following the strut adjustments. Straight ahead power off, accelerated (actually 1000 rpm to preclude engine stopping), and full power departure stalls were uneventful, wanting to fall off on left wing only during straight ahead stall. That tendency made for pleasantly busy "falling leaf" stalls; left and right 1 turn spins were normal, maybe requiring a little more forward stick at recovery than usual. Thankfully those old engineers made these birds stable throughout the range of adjustment.

Mike V.

Anyone know what the factory actually did for rigging on assembly? Saying one thing and doing another is the question. My experience resulted in similar measurements before and after flight...couldn't get the suggested 1 5/16" if I wanted. With VG's it's a non-event stall/spin series preceded by plenty of warning buffeting.

Gary

[Guest]

Re: Wing leveling

Hi Gary,

I was able to comply with the scheme shown in that drawing that has the 1-5/16" dimension after I purchased new struts from Univair.

Univair owned the type certificate at one time so I assume that their struts meet the original drawing spec.

My plane has been flipped at least once and repaired extensively, upper cabin section, longerons.

I believe that I made the repairs properly and maintained the geometry and since I could rig it that made sense.

What struts do you have, Univair, Wag, Alaska Airframes?

I did see two front struts that were different in length by a lot, about 1/4" or more. The factory which was open at that time said that was ok. Doesn't make sense does it?

Dave

[PA1195]

Re: Wing leveling

Hi Gary,

I was able to comply with the scheme shown in that drawing that has the 1-5/16" dimension after I purchased new struts from Univair.

Univair owned the type certificate at one time so I assume that their struts meet the original drawing spec.

My plane has been flipped at least once and repaired extensively, upper cabin section, longerons.

I believe that I made the repairs properly and maintained the geometry and since I could rig it that made sense.

What struts do you have, Univair, Wag, Alaska Airframes?

I did see two front struts that were different in length by a lot, about 1/4" or more. The factory which was open at that time said that was ok. Doesn't make sense does it?

Dave

I have Airframes' style struts installed this year that I bought from the original STC holder at Airforms (https://airforms.biz). They sold the STC to Airframes.

They are legal and came with proper paperwork. However...big pause...I think that over the years the Taylorcraft struts were built in at least two forms (see Airframes' info regarding end angles: http://www.airframesalaska.com/produ...-tcraftset.htm). And they may have been built with some variance in overall length between the end attachment holes as well. Not sure why if that's the case, but there's quite a time and manufacturing span between the original Taylorcraft and the F-22's or whatever they ended up with.

Without the prints (anybody have them and the strut dimensions?) I can only guess as to why my fixed dihedral is more than 1*, and why the spec of 1 5/16" can't be reached. More dihedral can offer longitudinal stability especially on floats. My plane on floats doesn't require a tail fin and is quite stable returning quickly to straight ahead after a kick on either rudder. My PA-12 floatplane would hunt for directional stability all day long in contrast despite the STC'd rudder spring beef-up kit.

I'm not concerned. We just lengthened the rear struts to within 1 turn of max extension (to leave some wiggle for later adjustment) and flew away. It performs as I'd expect it to without any nose, tail, or later wing heaviness and stalls and spins with VG's are a non-event.

Gary

[3Dreaming]

Re: Wing leveling

Gary, in my experience if your dihedral is off the problem is a bad repair in the fuselage rather than the struts.