Bear Mayday, down safely

[SkyvanDelta]

Re: Bear Mayday, down safely

I'm glad to see a company building parts for these airplanes. The pocket door segment gears on the Rare Bear are already overstressed, the market is one airplane that would require two parts. Engineering an improved version and making two parts without the backing of a huge company like Grumman (imagine ingots, forges and massive metalworking machines) is not impossible, but replicating and improving on the original will be exceedingly difficult, and not just financially.

Has the computer, attached to the machines changed this so parts can be easily made by programming the original specifications into the computer and allowing it to make original or better than new parts?

[GRNDP51]

Re: Bear Mayday, down safely

Has the computer, attached to the machines changed this so parts can be easily made by programming the original specifications into the computer and allowing it to make original or better than new parts?

I was thinking the same thing, technology has come such a long way we should be able to 3D print 4360's by now!! Lol, I don't see how ANY mechanism no matter how complicated couldn't be made in today's world

[Ebehne]

Re: Bear Mayday, down safely

The gears that move the pocket doors have been and probably will continue to be an ongoing issue on that airplane. I remember going through a box of spares and not having much luck finding any good ones. It would be an expensive part to make due to how complex it is, internal female spline precisely clocked to an external segmented gear. Not impossible, but very expensive, but there is such a small market for these parts that no one is willing to even tool up to do it.

I don't have a totally clear understanding of what these parts look like, but based upon the above description it sounds like someone could wire EDM them. Not really any tooling required, used all the time to make prototypes. It's pretty expensive, but I think it's likely reasonable for such a valuable and unique part. Considering that the landing gear issue is a recurring theme and potentially really dangerous for the plane/pilot, seems like the cost would be justifiable.

[toldjaso]

Re: Bear Mayday, down safely

I was thinking the same thing, technology has come such a long way we should be able to 3D print 4360's by now!! Lol, I don't see how ANY mechanism no matter how complicated couldn't be made in today's world

3D printing a part won't give you a forged part, I would guess?
Most of these type parts are forged, where they hammered them under great pressures to tighten up the grain structure.
(In my opinion, don't have the print that has the specs for these gears).
Anybody out there agree or disagree, and why?

[ChrisMX105]

Re: Bear Mayday, down safely

I would imagine that forgings would still be needed. The stresses of being opened and closed at 100+mph has to be insane.

[440_Magnum]

Re: Bear Mayday, down safely

Boil-off wins period.

Oh, I agree. I was poking a somewhat blunt stick at all the hoopla made over whether closing the oil cooler inlets and moving the air intake was a net win. Its the air intake part that's not a certain win or loss (well, there are people who are absolutely CERTAIN... on both sides!).

[440_Magnum]

Re: Bear Mayday, down safely

I would imagine that forgings would still be needed. The stresses of being opened and closed at 100+mph has to be insane.

I've never seen the parts, but from what you've said it sounds like something that couldn't be NC machined from a blank of forged material. That would be the obvious way to have the strength of a forging without the tooling costs- but if its a shape with a blind internal void (or any number of other constraints) then I could see where it would be impossible with current NC equipment.

Metal "printing" is on a faster curve than NC tools at the moment, maybe eventually forged-equivalent strengths will be possible. Not holding my breath, though.

[BellCobraIV]

Re: Bear Mayday, down safely

In 1973 Lyle's uncle Floyd Ledbetter had two sets of these gears and the segment gears made at an oil field machine shop in Kermit Texas. We just didn't have the budget to have more made. The parts are just stock F8F-2, I believe that Rod was able to acquire spares from Whittington.

[hm66sk]

Re: Bear Mayday, down safely

Yes, there is gonna be a strength difference between forged and machined from billet. I'm guessing the old ones have been welded and remachined a few times already?

[Desertdawg]

Re: Bear Mayday, down safely

In 1973 Lyle's uncle Floyd Ledbetter had two sets of these gears and the segment gears made at an oil field machine shop in Kermit Texas. We just didn't have the budget to have more made. The parts are just stock F8F-2, I believe that Rod was able to acquire spares from Whittington.

John,

Thanks for sharing that bit of history. Sharing your knowledge/memory about such simple things like "Lyle's uncle Floyd Ledbetter ....." is just so special. What more can I say - this is AAFO HangerTalk.

Thank you.

Hans

[knot4u]

Re: Bear Mayday, down safely

In 1973 Lyle's uncle Floyd Ledbetter had two sets of these gears and the segment gears made at an oil field machine shop in Kermit Texas. We just didn't have the budget to have more made. The parts are just stock F8F-2, I believe that Rod was able to acquire spares from Whittington.

John, I hope you understand my comments weren't meant as a jab to the current owner or crew, I was just pointing that some of the parts to keep flying are very difficult to obtain, much less improve. Your mod to the T-33 brakes are a good example of this, parts were becoming scarce and the airplane needed better brakes.

[BellCobraIV]

Re: Bear Mayday, down safely

John, I hope you understand my comments weren't meant as a jab to the current owner or crew, I was just pointing that some of the parts to keep flying are very difficult to obtain, much less improve. Your mod to the T-33 brakes are a good example of this, parts were becoming scarce and the airplane needed better brakes.

Not at all, I know you better than that. I was just filling in a little backstory for everyone else. Life is too short for all the hate, I don't go to the races anymore because if I went there I would have nothing to do. I'm a racer and that's just how I feel. I admire all these guys that still get up early, stay up late, work all year, to fight the fight. I was 6 when I started and 39 when I finally took a tip from Dwight and then Lyle. Now I'm a Hawks fan. This will be a tough Sunday against the Pack.
Go Voodoo! Go Hawks!

[knot4u]

Re: Bear Mayday, down safely

Not at all, I know you better than that. I was just filling in a little backstory for everyone else. Life is too short for all the hate, I don't go to the races anymore because if I went there I would have nothing to do. I'm a racer and that's just how I feel. I admire all these guys that still get up early, stay up late, work all year, to fight the fight. I was 6 when I started and 39 when I finally took a tip from Dwight and then Lyle. Now I'm a Hawks fan. This will be a tough Sunday against the Pack.
Go Voodoo! Go Hawks!

Wish there was a like button on this forum, glad to hear it sounds like things are going well. As far as racing airplanes is concerned, I always seem to get a little antsy this time of year. But I'm in my mid forties now and the price of admission required to participate is not one that I'm willing to pay, I have to admit those were some of the greatest years of my life. I suppose time washes away all the negative memories and the ones that remain are mostly positive.