Post by thevon on Jan 30, 2010 19:22:45 GMT 10
Wizard Rebuilt
This is a big day. These photos are the first evidence that the near-fatally injured Wizard is back in action, 17 months after its huge 160mph accident at Bald Knob. It’s been in a coma since then (wiggle sticks, nothing happens) but waved its control surfaces for the first time today. Since then it’s been getting better all day and gradually moving in a more co-ordinated way. It got some colour back this arvo and is now looking almost normal.
It’s a big deal for me as this was my first go at a “BIG” moldie repair. As you can see, the damage was not pretty and it really would have been quite justifiable to scrap it. Sean spent some time on it first, then we both pretty much gave up, and after a long break I started picking away at it. I’m sure I’ve spent a hundred hours on it, but it’s been a few hours here and there over a long period.
It was pretty much an engineering exercise piecing it all together and I got to try many techniques I’d never done before, such as making foil-shaped blue foam blocks to slip into voids where the skin damage was too bad. Bracing the broken spar inside and out with carbon and ply. Splinting the fuselage where so much was missing it was hard to work out what went where, and pumping up bike tubes to put internal pressure on molded cones made to fit the inside of the fuselage. I had to buy a carbon joiner from the US adn modify it. I cut hundreds of tiny slots into the balsa skin to soak CA in to fix delamination. Lots of carbon and glass cloth patches, lots of polyester filling putties (bog) and lots of sanding. I really work hard at the sanding and I have to say now that I’ve sprayed it, I can see that I didn’t do a good job! The biggest repair section has some highs and lows in the foil. There goes my panelbeating career.
The big innovation was that I have made an extra wing joiner box to take a 520gm stainless steel wing joiner/ ballast bar. It’s scary but exciting because the Wiz did get wing flex when DSing around 165mph – enough for Ezza and Sean to get pretty worried and talk me into stopping! I’m hoping that the extra stiffness from this new heavy joiner and the spreading of the weight into the wings will give it some stability. I’m not confident that it will, but it’s a good experiment.
The CG was still fine – in fact I removed a bit of the old nose weight to balance it. But the heavily repaired wing was much heavier and I had to add about 70gm (estimated) into the wing – which I put mid-span just outside the aileron servo.
The all-up empty weight of the Wiz is now 2.7kg. This is an increase of exactly 300gm from its original weight (so the repairs have added 230gm and the lead another 70). The combined weight of the new joiner and the old ballast bar is 1.16kg. So it can fly at 3.2kg with the extra joiner or in massive conditions the fully ballasted weight with the 600gm fuse ballast bar could be 3.8kg. Not sure if that will ever happen!
It’s all ready to fly with the settings back to the manufacturer’s recommendations etc. But I do feel worried that it have some problems, and might fly like a dog now. I suspect that there’s a bit of a twist between the 2 wings … ie I suspect that when I patched up the bad wing, the original joiner box may have been a bit rotated. Each side goes in fine on its own, but once one wing is on the pins the other one doesn’t line up perfectly with the pins and takes a bit of forcing to get on.
And I don’t know how to fix the various areas of broken wipers, etc etc. The paintwork is really basic but it’s not worth being fussy! I’ll be glad if it flies again, and anything else will be a bonus. It’s been a great education and a big challenge, and I’m glad that I did it.
(that wasn’t what I was saying this morning when I buggered something up, but that’s gliders!)
This is a big day. These photos are the first evidence that the near-fatally injured Wizard is back in action, 17 months after its huge 160mph accident at Bald Knob. It’s been in a coma since then (wiggle sticks, nothing happens) but waved its control surfaces for the first time today. Since then it’s been getting better all day and gradually moving in a more co-ordinated way. It got some colour back this arvo and is now looking almost normal.
It’s a big deal for me as this was my first go at a “BIG” moldie repair. As you can see, the damage was not pretty and it really would have been quite justifiable to scrap it. Sean spent some time on it first, then we both pretty much gave up, and after a long break I started picking away at it. I’m sure I’ve spent a hundred hours on it, but it’s been a few hours here and there over a long period.
It was pretty much an engineering exercise piecing it all together and I got to try many techniques I’d never done before, such as making foil-shaped blue foam blocks to slip into voids where the skin damage was too bad. Bracing the broken spar inside and out with carbon and ply. Splinting the fuselage where so much was missing it was hard to work out what went where, and pumping up bike tubes to put internal pressure on molded cones made to fit the inside of the fuselage. I had to buy a carbon joiner from the US adn modify it. I cut hundreds of tiny slots into the balsa skin to soak CA in to fix delamination. Lots of carbon and glass cloth patches, lots of polyester filling putties (bog) and lots of sanding. I really work hard at the sanding and I have to say now that I’ve sprayed it, I can see that I didn’t do a good job! The biggest repair section has some highs and lows in the foil. There goes my panelbeating career.
The big innovation was that I have made an extra wing joiner box to take a 520gm stainless steel wing joiner/ ballast bar. It’s scary but exciting because the Wiz did get wing flex when DSing around 165mph – enough for Ezza and Sean to get pretty worried and talk me into stopping! I’m hoping that the extra stiffness from this new heavy joiner and the spreading of the weight into the wings will give it some stability. I’m not confident that it will, but it’s a good experiment.
The CG was still fine – in fact I removed a bit of the old nose weight to balance it. But the heavily repaired wing was much heavier and I had to add about 70gm (estimated) into the wing – which I put mid-span just outside the aileron servo.
The all-up empty weight of the Wiz is now 2.7kg. This is an increase of exactly 300gm from its original weight (so the repairs have added 230gm and the lead another 70). The combined weight of the new joiner and the old ballast bar is 1.16kg. So it can fly at 3.2kg with the extra joiner or in massive conditions the fully ballasted weight with the 600gm fuse ballast bar could be 3.8kg. Not sure if that will ever happen!
It’s all ready to fly with the settings back to the manufacturer’s recommendations etc. But I do feel worried that it have some problems, and might fly like a dog now. I suspect that there’s a bit of a twist between the 2 wings … ie I suspect that when I patched up the bad wing, the original joiner box may have been a bit rotated. Each side goes in fine on its own, but once one wing is on the pins the other one doesn’t line up perfectly with the pins and takes a bit of forcing to get on.
And I don’t know how to fix the various areas of broken wipers, etc etc. The paintwork is really basic but it’s not worth being fussy! I’ll be glad if it flies again, and anything else will be a bonus. It’s been a great education and a big challenge, and I’m glad that I did it.
(that wasn’t what I was saying this morning when I buggered something up, but that’s gliders!)
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