In another thread trying to identify my aircraft, it was brought up that my wings, which have the fabric glued to the top of the ribs but not the bottom, is not correct.
I went out to the garage and tested it. Indeed, the top is very, very firmly glued, but the bottom surface of the wing, if I push on it from inside the wing, I can see five ribs down a gap forming.
Originally I was under the impression that because the bottom of the wing experiences pressure pushing the fabric into the wings, it was not needed, which is the same reason why I've only seen people rib-stitch the top of the wing. But I've now been told otherwise.
My question is this. What do I do? I was really, really hoping to not have to recover these damn wings, as I have never done so before, lack the supplies (though I can get them, but still, added expense I was not expecting) and generally.. it seems like a lot of work.
Am I screwed? I don't see any nice way of going in there while the fabric is still on and gluing it. Is it possible to remove the paint, cement, and redo the bottom of the wing without disturbing the top?
Any guidance would be much appreciated, I'd quite like my wings to stay together when I fly.
To add to this, here is a photo. also, it appears that the previous builder did add the tape to protect the fabric from rubbing on the ribs, just for some reason did not glue it. It seems like that would be harder but.. here we are.
The approved method per Polyfiber is the fabric is only glued around the perimeter of the wing with NO gluing to the ribs, heat shrunk,then rib lacing. So if that is good enough for certified planes , its goodnuff for ours. So, either you re-cover and glue to ribs the Minimax way, or you could add rib lacing. I'd use MEK to remove the reinforcement tapes on the bottoms, lace to the bottom capstrip only, then re tape.
The forum offers a Quick Reply option and this is one.
It takes serious determination to fly a Minimax in negative G. I've only ever done it once to see if I could get the engine to hickup. It did. And that was in level flight. I've no inclination to do that again.
When would you evvver need the Minimax's negative G capability?
If not, why would the under-surface covering of the wing ever need to be 'seriously' attached?
And, if you ever did need it, maybe the slight billowing out of the whole undersurface covering while the wing is negative-g loaded might actually help a bit ...
OK, maybe the cabin fever is getting to me a bit.....
I think it would be a mistake to fly without having the fabric attached to the bottom of the wing!
Could you reach through the inside of the wing with a brush and apply glue to the fabric and ribs. You could attach the brush to a long pole to reach the far ribs.
Thank you for your inputs. It is attached to the bottom of the wing but only at the front and back edges, and then it appears to be shrunk snug.
Does anyone here have a minimax without bottom rib glued fabric that has flown it, maybe even at high speed? Is it truly unnecessary as Antoni says?
Also, this thing is painted with house paint, will MEK make it's way through that?
Final question: am I correct that i can just MEK the bottom fabric, peel it off, then lay new cement and reattach and move on with my life? I'd love to brush it on from the side of the wing but I worry about precision. But if I can do that, it doesn't seem so bad..
I'd stitch the fabric to the bottom rib caps. Leave the paint alone and get some sail repair tape to cover the stitches. Paint the tape if you like or get the colored variety from Aircraft Spruce.
I think I'm going to redo the wing fabric, because of several reasons:
1: If he didn't glue this, what else didn't get glued properly? It would put my mind at ease to be able to fully inspect the wing structure.
2: I need to put a fuel tank in the wing anyway because my big stupid feet don't fit under the 5 gal when its in its normal location
3: I need to learn eventually, right?
So now I ask: Does anyone have a good guide? I plan on using dacron + poly-whatever the right product is, and finishing it with house paint. I found a few guides, and I have the one my minimax came with. But I'm curious if anyone has any extra opinions. I'd love to have a phone call with someone on here who has done a max with that system, just to ask questions. Please PM me if you are willing!
You made a wise decision. The covering process is easy and fun. Don't overthink it, no need to reinvent the wheel here.
My real concern though, is why is your fabric on the bottom of your wing is so far off the bottom of the rib? My fabric on the bottom of my wing lays right up against the bottom of the rib. As you can see from this photo.
I'm wondering if the trailing edge is lifting and coming lose causing this gap on your wing?
Oh I forgot to mention, yes, yes the trailing edge has failed and started to separate in a way that I believe is common for the older styles before some extra surface area was added for the glue to grip to. It's one of the repairs I have to make.
I'm not sure what wings I have. I was told that the way to tell was if it had 3 or 4 diagonal braces, and mine has 4. I also dug into more paperwork and found that I had a 1100 kit, but a light tail. hmm.
One deviation I do plan on making is using house exterior paint instead of the more expensive aircraft style, purely because I've seen so many people have good results and its so much cheaper. The question is do I still have to use poly-brush or do I only care about the cement..
I'm not sure what wings I have. I was told that the way to tell was if it had 3 or 4 diagonal braces, and mine has 4. I also dug into more paperwork and found that I had a 1100 kit, but a light tail. hmm.
One deviation I do plan on making is using house exterior paint instead of the more expensive aircraft style, purely because I've seen so many people have good results and its so much cheaper. The question is do I still have to use poly-brush or do I only care about the cement..
Well, it is very hard to tell to say for certain weather it is 3 or 4 from your pics, but one difference no one has mentioned so far is that the compression and drag struts in the 1030 are smaller stock than the other wings. As you can see from the picture of my wing, which is from a 1500r, that my compression struts are larger than yours. Thus leading me to believe your wings are built to 1030 standards.
I will be using latex house paint as well. Its my understanding that the latex will fill the weave so the poly-brush is not necessary. In fact, the latex paint won't stick to the dacron fabric so it has to encapsulate the fibers to gain a mechanical bond to the fabric, or else it will just peel off.
here are a couple good web sites on latex house paint and aircraft to get you started.
Ah, okay, makes sense. It looks like I'll need poly brush anyway, because its listed as necessary for bonding the fabric to the wood structure in the manual, but I won't need a TON of it. Yeah?
Thank you so, so so much for answering my questions. I'm sorry if a lot of them seem redundant. I'm just trying to be careful and not wind up spending money ordering a bunch of the wrong things.
Poly-tac, not poly-brush, is used to bond the fabric to the wood structure. Poly-brush is used to glue the tapes and patches on and to fill the weave of the fabric once the taped and patches are on. I'm using the "Superflight System". from what I can tell, its the same stuff as the poly fiber system but cheaper. You use the same glue you glue the fabric on with to glue your tapes and patches on. So I didn't have to buy two types of glue. Also, you cut the glue 2 to 1 with thinner right off the bat, so one quart of glue makes 3/4 of a gallon. More than enough to cover a minimax.
So if I use the superflight system, I can use it with dacron fabric like I have now, and I just need to get the U500 fabric adhesive, and MEK or acetone, and that's the only glue I'd need for my entire project? And just also use some lacing and rib stitching tape and covering tape like usual? The parts list is seeming quite small now, honestly, if I'm understanding correctly.
And just to broadly go over what I'll be doing:
-Using a combination of acetone/mek and sanding, remove the old fabric.
-Inspect structure, sand any sharp edges, make sure its all clean and ready to be covered again.
-spread U500 fabric adhesive, pre-thinned 3:1 with mek/acetone onto the structure and work along the wing to glue fabric on using guidelines in the poly-fiber manual.
-iron everything up as in the manual to get it all tight and nice
-lay the rib lacing tape on, do the rib lacing, then using more pre-thinned u500 fabric adhesive, glue the 2" strips of covering tape over the rib stitching
-let everything dry fully for a while, then move on to painting, following that latex painting website.
Am I missing any steps? Do I have to pre-coat the wood structure in the aircraft with anything before putting on the pre-thinned u500 or is MEK'ing the old polyfiber stuff off and sanding it clean good enough? Thank you! Once I get this straightened out I'm gonna order my supplies. 1 Quart of u500 is enough to do the entire minimax?
Yes, and yes, that is the only glue you will need. Sounds like you got it all figured out except superflight has their own manual. Unfortunately it's not a free download, it will cost you $10.00 bucks but it is worth it. Superflight has their own brand of dacron 1.8 oz uncertified fabric, it's all dacron regardless, but superflight is cheaper @ $7.75 a yard. Superflight recommends acetone and that is what I used.
You will brush two coats of glue thinned 2:1 on the airframe then with your fabric in place you will go over it where you brushed glue on the airframe with glue thinned 3:1 and rub the fabric down into the reactivated glue to glue it in place.
I wouldn't go all the way up to 350 degrees, If I remember right, the team covering video recommends you only shrink up to 325 and that's just up to the rear spar. From the rear spar to the trailing edge is just 225 max. That keeps the trailing edge from breaking lose and also from scalloping from the stress of the stretched fabric.
Sounds about right, I highly recommend you follow the superflight manual. The wood structure should already be varnished. But if not, you will need to varnish it with a two part varnish or just use thinned epoxy like I did. Cleaning it off with acetone should be good enough, the manual will tell you if you need to do more.
Yes, one quart thinned 2:1 will give you 3/4 gallon of glue. More than enough to cover a minimax. The fabric sub kit from team only comes with 2 quarts of poy-tac. You will end up with 3 quarts of U500.
Sounds good to me, thank you so much for your help. You've been very clear and easy to understand. I'll order the stuff soon.
When you say "then with your fabric in place you will go over it where you brushed glue on the airframe with glue thinned 3:1 and rub the fabric down into the reactivated glue" do you mean let the glue on the airframe dry, then place the fabric on it and then put 3:1 glue on top of the fabric so it soaks through and reactivates the glue, or do you mean lift the fabric, paint fresh 3:1 glue on so it reactivates, then put the fabric back down and rub it down onto the reactivated glue so it soaks it all up?
Also, is there a reason this dacron is so cheap? I can see its a little thicker.. But it seems like at a 1oz/yd difference, the total weight of all the fabric on the wings works out to 4.7lb vs 2.9lbs... what am I missing? Will the thicker fabric ruin something?
This is just a thought. There seems to be a passion for using "latex" house paint, that is a water based acrylic pigment paint, on these aircraft. However I'm pretty used to the costs of painting things, and when I look at the cost of a complete Poly-Fiber fabric job through the PolyTone top coats you'd normally use on this type of aircraft, I just don't see the advantage of the "lower cost" paint. Yes the PolyTone is more expensive than the "latex", but it seems that, given the time, effort, and small amount of paint involved, this is a very small price difference. These aircraft aren't that big. They don't need that much paint. This is just my analysis. I'm not trying to talk anybody into anything.
This is just a thought. There seems to be a passion for using "latex" house paint, that is a water based acrylic pigment paint, on these aircraft. However I'm pretty used to the costs of painting things, and when I look at the cost of a complete Poly-Fiber fabric job through the PolyTone top coats you'd normally use on this type of aircraft, I just don't see the advantage of the "lower cost" paint.
First of all, this is what you can achieve with latex house plaint
Vs poly tone
latex is $50 a gallon and comes in any color under the sun. Polytone is $100 and up (depending on color choice) a gallon with very limited color choice. Latex has the UV blocker built in. With Poly tone you will have to buy Poly spray for UV blocker @ $100 a gallon and you will need just as much if not more than poly tone essentially driving the cost of poly tone to $200 a gallon. Latex also fills the weave with the first coat. With Poly tone you will need poly brush to fill the weave @ $100 a gallon. We are now at approximately $300 a gallon for poly tone.
Yes the PolyTone is more expensive than the "latex", but it seems that, given the time, effort, and small amount of paint involved, this is a very small price difference. These aircraft aren't that big. They don't need that much paint. This is just my analysis. I'm not trying to talk anybody into anything.
Tom
My estament for my minimax was $550 minimum for poly tone, thats 1 gallon poly brush, 1 gallons poly spray, and 2 gallons for color (one white and one blue). Vs $100 for 2 gallons of latex (one white and one blue) for the same if not better results.
When you say "then with your fabric in place you will go over it where you brushed glue on the airframe with glue thinned 3:1 and rub the fabric down into the reactivated glue" do you mean let the glue on the airframe dry, then place the fabric on it and then put 3:1 glue on top of the fabric so it soaks through and reactivates the glue, or do you mean lift the fabric, paint fresh 3:1 glue on so it reactivates, then put the fabric back down and rub it down onto the reactivated glue so it soaks it all up?
Also, is there a reason this dacron is so cheap? I can see its a little thicker.. But it seems like at a 1oz/yd difference, the total weight of all the fabric on the wings works out to 4.7lb vs 2.9lbs... what am I missing? Will the thicker fabric ruin something?
Let the glue dry and then soak through. It all will become clear with the manual.
Once you shrink it that heavier fabric will turn your minimax into a pile of sticks. Its "not sold by the yard. NOT for use on certified aircraft" superflight SF104 isn't certified either, its 68" vs 72", and your just adding dead weight cause you don't need fabric that heavy for a minimax.
And paint aircraft with glue, place fabric on top, then paint over the cemented areas on top of the fabric with more thinner glue, understood! I will be getting that manual.
Having had a close look at the photo of the inside of ITman496's wing, I think it's an 1100 wing. I can see the joint where three of the anti-drag struts meet the rear spar. I can see 3 joints, and of course in the photo you can clearly see the 4th drag strut on the left of the picture. I've copied the picture and ringed the 3 rear joints I can see with red circles, plus I've arrowed the 4th drag strut with a red arrow. I've attached the amended photo below so that you can see what I mean.
Yeah, I'm not sure what I have. I found paperwork that says at least the fuselage is an 1100, I have a light tail, but with heavy tail mounting bolts. I have 4 braces in my wing, but according to toliver, my braces are thin looking compared to his. I'll have the fabric off eventually, so we shall see what that brings me. I plan to fully rib stitch the wing mainly because.. why not.
Is there any other mods I should be doing to the wing structure that have changed since 1990? I already have to fix the trailing edge strip that are separating from the ribs due to fabric tension.
I see what you mean bob.hood. Could well be the compression members in an older 1100 wing may have specified smaller material. According to the plans, the compression members in an 1030 wing are RS-5. The 1100 prints specify RS-5 and RS-7 for the compression members. So maybe the builder built a 1030 wing and added the fourth drag strut. Either way I'm sure your wing will be just fine.
RS stands for Raw Stock. The plans come with a material reference sheet that list all the sizes and composition of materials used in the construction of a minimax. Each listing has a raw stock number.
RS-9 = 3/4 x 3/4 x 142" white pine RS-5 = 1/4 x 3/4 x 142" white pine RS-7 = 1/2 x 3/4 x 142" white pine
I see what you mean about the compression struts. I've attached the portions of the relevant diagrams below, and also the relevant bits of the diagrams showing the stuff the anti-drag struts are made of too, so that you can compare the differences between the 1030 and 1100 wings.
From what I can see, it looks as though the builder used 4 of the 1100 type anti-drag struts and all of a similar size (rs9, rs as opposed to the 1030 struts (rs9, rs8, rs7), but used the 1030 compression strut stock rs5, instead of using rs5 for the top stringers and rs7 for the lower ones.
Logged
as opposed to the 1030 struts (rs9, rs8, rs7), but used the 1030 compression strut stock rs5, instead of using rs5 for the top stringers and rs7 for the lower ones. 
