# Flight Club - Ultralight Build Log

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#### proppastie

##### Well-Known Member
Log Member
so we were wondering if this forum had any suggestions in preventing galvanic corrosion?
riveted 2 or 3 inch long aluminum piano aircraft hinge....you could rivet in the control surface neutral position to the bottom of the tubes with hinge at 180 deg ...you would not necessarily have to be on center I would think because of your slow speed....you also could gap seal.

#### proppastie

##### Well-Known Member
Log Member
oops without stress analysis of the tube wall make that a bolted through with hardwood filler whole tube instead of pop rivet to the one side .....enough rivets on one side might be strong enough but might not depending on the number of rivets......might do a pull test on 4 or 5 rivets on a short piece.

Log Member

#### maya.ayoub.32

##### Well-Known Member
HBA Supporter
but have you ever looked into Oratex
Thanks for the tip! We've been planning to use Polyfiber to cover the wing, but haven't done so yet - so this information is coming at the perfect timing! We'll definitely look into it, though since our wing is so large, Polyfiber already costs us $4k so thank you Proppastie for the heads up that cost will be a large worry. This was the only manual I was able to find online - do you know if they have more in-depth instructions? Oratex very expensive #### maya.ayoub.32 ##### Well-Known Member HBA Supporter II am currently looking at Hipec....as they claim you do not have to rib stitch Oh man we'd love to hear updates on this! It'd be amazing not to need to rib stitch! #### maya.ayoub.32 ##### Well-Known Member HBA Supporter speed, length of the arm (distance) to the CG. .....copy similar speed sized aircraft ....however it might look also to scale a certified aircraft because homebuilts experimental are not necessarily same ( as docile ) designed..... There is a chapter in Glider Criteria P20 on "balance loads"....But I have not studied it as I copied the Carbon Dragon which is a very slow aircraft with large tail surface and arm because it is so slow. Plans from my signature block at the Irish site. Gotcha! Carbon Dragon looks about the same as our plane, ratio of body to wing wise, so thank you for the reference. Looks like they have tons of information online which we'll check out and get back to you on. We'll be running our calculations on the Carbon Dragon and Legal Eagle soon to ground our forums too - I have a feeling our tail doesn't need to be as large as it currently is. Just found the Glider Criteria off your website - it has incredibly helpful information on testing our control system and joints too which will come in handy soon - Thank you! #### maya.ayoub.32 ##### Well-Known Member HBA Supporter The issues with removable tail parts is good attachment and easy and safe rigging. Taking something apart always has an issue of forgetting to attach something. Forget a bolt or nut or like. Covering that is all you need to do. Would this be the only issue? We're just concerned about our attachment being weaker than the weld itself, but if that's not a concern then storage and logistical-wise it would save a lot of hassle if it were detachable! #### maya.ayoub.32 ##### Well-Known Member HBA Supporter It might be better to use the existing hinges on 1" aluminum, if your weight works out OK. If you make your own hinges I would be concerned with binding issues. Would binding issues still be an issue if we're creating hinges that look like this? If so, then better not risk it and go with your suggestion with sticking to 1" aluminum. Sounds like a detachable tail is our best option then? #### bmcj ##### Well-Known Member HBA Supporter Thanks for the tip! We've been planning to use Polyfiber to cover the wing, but haven't done so yet - so this information is coming at the perfect timing! We'll definitely look into it, though since our wing is so large, Polyfiber already costs us$4k so thank you Proppastie for the heads up that cost will be a large worry. This was the only manual I was able to find online - do you know if they have more in-depth instructions?
Like I said, I’m a big fan of Poly Fiber and have used it for many years (partly because I was good friends with Ray Stits who developed the PolyFiber fabric and processes).

The reason I mentioned Oratex even though it cost more is because you can save labor and (I think) weight because it needs no paints... it is a fabric only finished surface. The extra cost is partially mitigated by the fact that you don’t have to buy paint. I’ve never used Oratex myself, so I make no claims about its quality or ease of application. Poly Fiber, on the other hand, I can heartily recommend.

Hipec... I’ve never used it and I don’t really know anything about it.

#### maya.ayoub.32

##### Well-Known Member
HBA Supporter
riveted 2 or 3 inch long aluminum piano aircraft hinge....you could rivet in the control surface neutral position to the bottom of the tubes with hinge at 180 deg ...you would not necessarily have to be on center I would think because of your slow speed....you also could gap seal.
Sorry I'm not sure I fully grasp the topic - is the idea is to use piano hinges as a mechanical stop to not over-rotate and lose control of our rudder/elevator? Or is it to use piano hinges in place of the Airdome attachments? We've been recommended against using piano hinges on the aileron in the past because of their tendency to bind which is why we're using a torque tube - would they be advantageous at the tail, however?

#### maya.ayoub.32

##### Well-Known Member
HBA Supporter
Like I said, I’m a big fan of Poly Fiber and have used it for many years (partly because I was good friends with Ray Stits who developed the PolyFiber fabric and processes).

The reason I mentioned Oratex even though it cost more is because you can save labor and (I think) weight because it needs no paints... it is a fabric only finished surface. The extra cost is partially mitigated by the fact that you don’t have to buy paint. I’ve never used Oratex myself, so I make no claims about its quality or ease of application. Poly Fiber, on the other hand, I can heartily recommend.

Hipec... I’ve never used it and I don’t really know anything about it.
Oh man, I love Ray's commentary throughout the manual - what a legend. We've just been taking into account the necessities to covering the wing and not too much on the paint - so good tip to calculate that now and compare it to Oratex.

To double check, rib-lacing is a necessity for the Poly Fiber covering system right? And just gauging-wise off the top of your head, does 4k sound about right to cover a 32 ft wingspan by 6 ft chord wing? We were a tad surprised by the heavy expense after calculating it. Thank you #### Aerowerx ##### Well-Known Member Would binding issues still be an issue if we're creating hinges that look like this? If so, then better not risk it and go with your suggestion with sticking to 1" aluminum. Sounds like a detachable tail is our best option then? Those should work ok, I think. I'm no expert with hinges like others here, but another thing to consider is that you will have two or more of these hinges. They will have to be perfectly aligned with each other or you will get binding. The way to prevent that is to use a long rod the same size as the pin. Stick it through all the hinges during initial assembly. A detachable rudder and tail would be a good idea IMHO, for when you have to do repairs or fabric replacement in the future. There is a concept in engineering design that seems to be ignored a lot. That is "Design for Maintenance"---make it easy to do repairs and routine work (I had a car once where you had to take the center dash board apart to replace a backlight fuse!!!) #### proppastie ##### Well-Known Member Log Member Sorry I'm not sure I fully grasp the topic No use the piano hinge as a hinge....all of the concepts shown will work ....if you keep the tubes true/straight/parallel you should not get binding. Former drawing showed the range of movement and sorry it was confusing.......30 deg each way is what my plans show for the Carbon Dragon #### Attachments • 45.1 KB Views: 2 Last edited: #### proppastie ##### Well-Known Member Log Member #### bmcj ##### Well-Known Member HBA Supporter To double check, rib-lacing is a necessity for the Poly Fiber covering system right? And just gauging-wise off the top of your head, does4k sound about right to cover a 32 ft wingspan by 6 ft chord wing?
Yes, I can’t recall Ray ever approving a wing cover without rib stitching. If covering a certified aircraft, whatever method was used for the secondary securing of fabric is also the method that should be used on the recover. In other words, if it was stitched by the factory, it should be stitched during the recover. If, like the Aeronca Champ, it was secured by PK screws, then the same type of PK screws should be used for the recover. If it is a wood sheeted wing that the fabric is glued to without being stitched (kind of difficult to stitch through wood, LOL), then the recover should be glued down in a similar manner. Since you are building a Part 103, it is not certified, so you can decide how you would like to attach your fabric... same as for E-AB, but Ray would still strongly suggest you stitch or screw for a secondary attachment. The reason is that the glued fabric attachment has a low peel strength, so lower pressure on top of the wing can cause separation. BTW, stitching can be laborious, but it’s really not that bad once you get in the groove; I actually enjoy stitching.

I haven’t covered a plane in a long time... it used to be cheap, but I know the costs have gone way up. I think the PolyFiber website or maybe the Aircraft Spruce website give some estimated costs for covering some example aircraft. I’ve heard estimates around $4K, but I am not sure if that is the entire plane of the wing alone. For your Part 103 project, you can probably use the super lightweight Stits sailcloth to save weight, and you can buy the non-PMA fabric to save significant cost. For additional weight savings, you could skip or go light on the silver UV sanding coats if you are going to park it indoor out of the sunlight. You can also get UV block additive to add to your colored paints. Last edited: #### Hot Wings ##### Grumpy Cynic HBA Supporter Log Member Oh man we'd love to hear updates on this! It'd be amazing not to need to rib stitch! I can't remember the details of your rib construction so this may not apply: Yes, it is a great time saver, but it isn't an option for some types of rib construction. The ultralight type foam ribs with a glued on cap-strip of aluminum or composite may be limited by the strength of the foam/bond line when placed in tension. Internal rib stitching - wrapping the ribs with the equivalent of rib stitching before covering may be an option. #### Protech Racing ##### Well-Known Member A small piece of cotton sheet draped over the top of the rib at 30% will allow using a hook needle to stich through the cotton . This puts everything in shear. #### memde ##### New Member Thanks for the tip! We've been planning to use Polyfiber to cover the wing, but haven't done so yet - so this information is coming at the perfect timing! We'll definitely look into it, though since our wing is so large, Polyfiber already costs us$4k so thank you Proppastie for the heads up that cost will be a large worry. This was the only manual I was able to find online - do you know if they have more in-depth instructions?
Just sent you a link to our Oratex folder which contains all of the information we were able to assemble on the subject. Let us know if you have any questions.

#### proppastie

##### Well-Known Member
Log Member
using the ultra-lite method and one of two colors of Poly-tone that already has the silver in it......you should save weight and cost......If you decide to use the Polyfiber method.......Use non certified fabric. ....for example.....remember a yard of this fabric is 72" x 36" when figuring square ft.....(18 sq ft).....to further cut down on cost there is always Latex house paint .......
Ceconite Fabric - Wicks Aircraft Supply Company

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#### bmcj

##### Well-Known Member
HBA Supporter
Yes, it is a great time saver, but it isn't an option for some types of rib construction.
The ultralight type foam ribs with a glued on cap-strip of aluminum or composite may be limited by the strength of the foam/bond line when placed in tension.
+1 on Hot Wings. If the ribs are foam, they probably will not support any attachment that just bonds to the cap strip without failing the rib’s foam structure. Rib stitching is the safest way to go because it ties the loads to both the upper and lower surfaces and to the entire rib structure.