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Weight of Berkut Retractable Gear?


airwrench
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Does anyone have a rough estimate on the weight impact of the Berkut style retractable gear? (kinda like the aesthetics of the infinity but I feel they would not deal with a hard landing as well as the berkut).......not to mention that they went kind of wild with carbon fiber on the skins of the berkut.:scared:

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.... (kinda like the aesthetics of the infinity but I feel they would not deal with a hard landing as well as the berkut).......

I'm always fascinated when people have "feelings" about things like this. On what do you base these "feelings"?
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Does anyone have a rough estimate on the weight impact of the Berkut style retractable gear?

I don't, but there is a lot of metal in there. The gear legs are all metal, and there are metal inner workings with hydraulics. Guessing, I'd come in at 103 lbs.

 

(kinda like the aesthetics of the infinity but I feel they would not deal with a hard landing as well as the berkut)...

Hmm... I personally enjoy looking at Berkut landing gear more than those "spindly looking" Infinity gears.

 

I'm always fascinated when people have "feelings" about things like this.

Marc, sometimes you're just "too much" -- I mean that in the best of ways, and certainly do not mean for you to adjust your posting style in any way whatsoever.

 

If you do reference the online defintion of feel from Merriam-Webster, you will see that airwrench used the word quite acceptably. :)

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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I don't, but there is a lot of metal in there. The gear legs are all metal, and there are metal inner workings with hydraulics. Guessing, I'd come in at 103 lbs.

What makes you think the gear legs are metal? I couldn't find a definitive answer, but:

 

http://www.berkut13.com/berkut15.htm

 

says:

 

"The first step was to micro fill, and primer the gear legs -"

 

You don't do that with metal legs.

 

And "103 lbs."? That's a strange number to guess.

 

If you do reference the online defintion of feel from Merriam-Webster, you will see that airwrench used the word quite acceptably. :)

From a semantic standpoint, sure. From a "make a decision regarding engineering data", uh-uh.

 

If the guy that designed my wing spars put as much spar cap material in it as he did because it "felt" right, I'd chop the plane up and never get in it again. Either the Infinity gear is as good as the Berkut gear from a drop test standpoint (and since Infinity has published FAA drop test results, and Berkut hasn't, I'd say that if anything, it's better) or it isn't. Having "feelings" about it doesn't change anything.

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The "Feelings" I was referring to were those abnormal times when on flair there seems to be this demi-god that wishes to slam both you and your aircraft firmly on the tarmac with design challenging force. Somehow the fuse only appears to be able to distribute this force evenly across the airframe, the strakes I don't know:confused:

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What makes you think the gear legs are metal? I couldn't find a definitive answer, but:

 

http://www.berkut13.com/berkut15.htm

 

says:

 

"The first step was to micro fill, and primer the gear legs -"

 

You don't do that with metal legs.

 

And "103 lbs."? That's a strange number to guess.

 

From a semantic standpoint, sure. From a "make a decision regarding engineering data", uh-uh.

 

If the guy that designed my wing spars put as much spar cap material in it as he did because it "felt" right, I'd chop the plane up and never get in it again. Either the Infinity gear is as good as the Berkut gear from a drop test standpoint (and since Infinity has published FAA drop test results, and Berkut hasn't, I'd say that if anything, it's better) or it isn't. Having "feelings" about it doesn't change anything.

Yes, the drop test was performed..........on an EZ??NO:envy:
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I don't, but there is a lot of metal in there. The gear legs are all metal, and there are metal inner workings with hydraulics. Guessing, I'd come in at 103 lbs.

 

Hmm... I personally enjoy looking at Berkut landing gear more than those "spindly looking" Infinity gears.

 

Marc, sometimes you're just "too much" -- I mean that in the best of ways, and certainly do not mean for you to adjust your posting style in any way whatsoever.

 

If you do reference the online defintion of feel from Merriam-Webster, you will see that airwrench used the word quite acceptably. :)

Yes, the feel, the hunch, the presumption, the gut feeling, and all of those adj's get my point nicely along...........moreso, aircraft do have fatigue lifes, and little data is available for the strakes on the ez
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Yes, the drop test was performed..........on an EZ??NO:envy:

Great feed for the Berkut landing gear, and yes, all parts and components do "evolve" over time, would be nice to have a set in the shop to test on my own..........maybe time to fire up the cad, smile at all the designers, and head out on my own personal quest for landing gear. (and finally get some use out of my shopsmith nine thousand, lol):cool:
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What makes you think the gear legs are metal?

I must have been thinking of this experimental Berkut: http://www.airforce-technology.com/projects/s37/ :)

 

Interesting. I always thought the leg feet and linkages were definitely metal, as well as the legs themselves. However, based on Jame's Web site, Iit looks like Jame's gear may be all composite upwards of the feet. Still, he writes this in the 3rd paragraph from the bottom: "Years ago, before the Berkut gear went to metal castings at the top, Dave discovered that after several hard landings the gear became 'softer'." Perhaps this refers to the linkages. I don't know.

 

My mistake... they're not all metal.

 

And "103 lbs."? That's a strange number to guess.

Just trying to be touchy-feely. I might lower it one stone knowing what I know now.

 

Either the Infinity gear is as good as the Berkut gear from a drop test standpoint (and since Infinity has published FAA drop test results, and Berkut hasn't, I'd say that if anything, it's better) or it isn't.

Your point is well-taken (by me at least) -- best to consider facts and real world examples.

Jon Matcho :busy:
Builder & Canard Zone Admin
Now:  Rebuilding Quickie Tri-Q200 N479E
Next:  Resume building a Cozy Mark IV

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  • 10 months later...

My E-Racer landing gear uses all fiberglass gear legs I bought from Shirl Dickey before he went to all carbon fiber legs and later with metal ends for the Berkut gear I have seen. There are no metal ends on the legs I have and the axles bolt to the bottom of the leg like on a Long-Ez or Cozy. I was worried about the all fiberglass legs at first but have had no problems with them so far. My empty weight is 1100 lbs and I have made some good hard landings on occasion. The weight of the retract gear would be increased by the metal overcenter linkage as well as whatever hydraulic cylinders and pump you use. It all adds up to a fair amount of weight if you total it all up. I feel all this extra weight not desirable for takeoff performance reasons.

post-236-14109015506_thumb.jpg

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Here's an analysis of the Berkut gear.

 

http://www.atnet.it/lista/Aircraft/milwauk.htm

 

The legs started out all carbon. There were failures (creep) at the bottom, so we went to aluminum bottoms. Then failures (delams) at the bend, so we went to aluminum top ends.

 

I don't know the overall weight, including the hydraulic pump and fluid. It's well under 100 lbs. Especially if you're looking at the increase over the standard gear.

 

We did a test for PFA certification in England, hitting at 800 fpm with a video camera in the gear bay. 8 landings, no damage.

 

We looked at going to all aluminum, it would have been much more expensive and heavier.

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