Once upon a time, an RV was built from raw sheet by forming over hammerforms. Obviously we don't do much of that anymore, although there are some remaining plans-builders who do.
Anyway, this is a rescue project, a fuselage former for a Yak 50, the station being about a foot aft of the firewall. The airplane did a bit of belly crawling following a gear problem, happily on smooth grass, and the original former wasn't salvagable. Apparently the parts are no longer available from the Mother Country, so the repair required the fabrication of a new former.
I was able to pull measurements from another 50, and combined with the remains of the broken former, I got the shape nailed down in AutoCad. Took the .dwg file to a waterjet shop and had them cut the basic hammerform profile from a chunk of 3/4" 6061T6 plate pulled from my scrap bin. The rest is hand work, notably edge radius, lightening hole locations, and a die to press the lightening hole flanges.
First I tried a practice part in 2024-T3, just to see if I could avoid a trip to the heat treat shop. As expected, it wasn't possible to shrink T3 enough at the wide outer flange. Probably could have done it with flutes, but the original Russian part had none, and the goal was a exact copy. So, out came the 2024-0 soft stuff. One quick practice part to tune the tools, then this part. I'll probably send it to the rib shop that builds your RV ribs for Vans, and ask them to tuck it in with a batch for heat treating to the T3 level.
Hammerform on top, new Russian-American fuselage former on bottom. And yes, if your local Yak flyer happens to develop a bad belly rib, tell him you know where to get a duplicate
Anyway, this is a rescue project, a fuselage former for a Yak 50, the station being about a foot aft of the firewall. The airplane did a bit of belly crawling following a gear problem, happily on smooth grass, and the original former wasn't salvagable. Apparently the parts are no longer available from the Mother Country, so the repair required the fabrication of a new former.
I was able to pull measurements from another 50, and combined with the remains of the broken former, I got the shape nailed down in AutoCad. Took the .dwg file to a waterjet shop and had them cut the basic hammerform profile from a chunk of 3/4" 6061T6 plate pulled from my scrap bin. The rest is hand work, notably edge radius, lightening hole locations, and a die to press the lightening hole flanges.
First I tried a practice part in 2024-T3, just to see if I could avoid a trip to the heat treat shop. As expected, it wasn't possible to shrink T3 enough at the wide outer flange. Probably could have done it with flutes, but the original Russian part had none, and the goal was a exact copy. So, out came the 2024-0 soft stuff. One quick practice part to tune the tools, then this part. I'll probably send it to the rib shop that builds your RV ribs for Vans, and ask them to tuck it in with a batch for heat treating to the T3 level.
Hammerform on top, new Russian-American fuselage former on bottom. And yes, if your local Yak flyer happens to develop a bad belly rib, tell him you know where to get a duplicate
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