This question is specific to Max 103, though it may apply to other Max models as well.
In an effort to reduce weight, I am thinking of NOT covering the front fuselage with fabric, but limit the fabric-covering to aft of station 4, starting from just an inch ahead of rear spar carry through location , extending back till the tail. I am also not planning to cover the landing gear legs, but just paint over them.
Is it safe to assume that the fabric covering on the front fuselage-box has NO structural role? I ask this because Ceconite is quite strong, and when it envelopes the fuselage like a tight sleeve, it could add to structural strength of the box.
By rough calculation /estimate, I think my build is coming close to about 262 - 265 lbs, so I need to shed a few lbs. (This number could vary on final weigh-in, but I would prefer to err on the safe side.)
I had considered leaving the plywood forward section uncovered when I built my MiniMAX. I finally decided to cover it anyway. My biggest reason to do it was a concern that the fabric edge would end up lifting/peeling from the plywood and I'd end up facing a lot of re-work at some point. Probably an unlikely fear, but that's what I did. I do believe it would save some weight. Not so much the fabric, but the paint to fill the weave.
When I acquired my 103 legal Mini Max it had been damaged, including total wipe out of the landing gear legs. My new gear legs were finished with Min Wax polyurethane, (no fabric), and today, after 4 years, they look better then the rest of the airplane.
Thanks for your helpful replies. I can go ahead knowing that many have done it before me.
A small question remains. This is only of academic interest. Does the fabric help in any way at all (other than cosmetic) ?
1. Probably it may add a wee bit strength to the box structure. (?) 2. It may help dampen the engine vibrations to a small degree. (?) 3. In cold weather it may help in better insulation of fuselage ( useful for those with closed canopy ). (?)
UV protection. Not that it is the only way , but fabric with a good silver coat has proved itself as pretty darn good at keeping uv from penetrating, and lets face it, about every hour these craft are flown they are going to be hit by clear skies. Even if its stored in a hanger out of the light, by a 1000 hours your equaling 100 ten hour days of direct sunlight, and that takes a tole on any plywood, aircraft grade or not.
I used housepaint (called latex I think in the US) which includes a UV barrier. House walls, often of wooden cladding out here in the Australian wilderness, stand up to years of very intense sun every day for a number of years without their modern paint finish failing.
I made a test section of wing which I painted with the same paint I used on my Max. This has been outside in full sun now for over 2 years, or in excess of 5000 hours of sunshine (on average over 24 months). It has also seen occasional heavy rain, and - rarely - sub zero temps.
So far, I can't see any deterioration in the paint surface, or the underlying Dacron.
So, although I wouldn't ever suggest leaving a wooden aeroplane outside, I'm happy my plane is amply protected for the few hours it sees per year when I'm flying.
Thanks for your helpful replies. I can go ahead knowing that many have done it before me.
A small question remains. This is only of academic interest. Does the fabric help in any way at all (other than cosmetic) ?
1. Probably it may add a wee bit strength to the box structure. (?) 2. It may help dampen the engine vibrations to a small degree. (?) 3. In cold weather it may help in better insulation of fuselage ( useful for those with closed canopy ). (?)
Not an effort to sway your decision in any way, but just something to think about. It might be a good idea to check your final finishes compatibility with gasoline, aside from the ocassional drop or two getting spilled on it, if it's a vented cap the fumes may also become a problem. A local EAA guy had to permanently ground his plane because his fuel tank vent line cracked just before it exited the wing, the gas fumes ate the whole dowfoam core out of his rutan style wing into a mass of blue goo. I've heard of another guy a chapter over that had the same problem when he left his solid core composite plane in a trailer for month over the summer without draining his gas tank. Atleast on a max it would only be cosmetic unless it was not repaired it a timely manner.
UV protection. Not that it is the only way , but fabric with a good silver coat has proved itself as pretty darn good at keeping uv from penetrating, and lets face it, about every hour these craft are flown they are going to be hit by clear skies. Even if its stored in a hanger out of the light, by a 1000 hours your equaling 100 ten hour days of direct sunlight, and that takes a tole on any plywood, aircraft grade or not.
If, whatever coating you propose to add as UV barrier to the fabric, is instead applied directly on to the plywood, then the UV protection is taken care of even without the fabric.
I plan to apply one coat of Ekofill directly to plywood before applying one cross coat of latex exterior paint-cum-primer. I like Ekofill because I found it to be a very good and smooth base coat. The UV blocking property is a bonus.
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