Bush Gear guys I need a favor!

[C5Engineer 1170]

I need a favor from one of you guys running bush gear....Bandit?? I am ordering some of the speed fairing material from Kitfox. They will break up their kit and cut it down shorter for cheaper shipping. Right now I need to know if two 4 foot pieces would be enough to make all the pieces needed to snap onto all the exposed gear leg sections including the cabane portion. Can someone measure out all the lengths for me and see if 96" is enough total and that 2 pieces cut to 4 foot would work? Round up if anything is close.

 

I'd do this myself but I'm ,literally half a world away from my plane deployed at the moment. An 8 ft piece of that stuff from them is $62 if anyone was curious and the shipping quote for Four 4ft pieces was $21.

[EDMO 1078]

Joey, I believe that UPS will ship up to 8 feet at no extra cost. Did you check that out? Dang - Does that mean the strut fairings would be about $250 plus shipping - I have a set of old J3 struts for a pattern - need to start a new fiberglas business and enhance my retirement.....Sorry for 2c worth - Cant keep big mouth shut...Hope someone can help you.

EDMO

Edited 17 Jun 2013 by Ed In Missouri

[Av8r3400 1179]

Joey - What about some locally sourced balsa wood farings from a hobby shop? $62 for 8', even without the shipping, just seems overly expensive to me. IMO.

[Bandit 286]

Joey,

The 2 cabane peices are1'5", 1'2".  The front tube is 2' , back tube 2'3".

[C5Engineer 1170]

Thanks Ed I'll ask KF about that. It sounds like that would make it easier based on the measurements I've recieved from Bandit and another friend of mine with the Airdale gear. Larry Balsa would get destroyed going the places I go. Leni said he's running it on his struts and it's really heavy so that's a thought too.

[EDMO 1078]

Thanks Ed I'll ask KF about that. It sounds like that would make it easier based on the measurements I've recieved from Bandit and another friend of mine with the Airdale gear. Larry Balsa would get destroyed going the places I go. Leni said he's running it on his struts and it's really heavy so that's a thought too.

Joey,

IMO, you need carbon fiber / Kevlar fairings to take the punishment you give them !

Well, after the FG gets ragged, you can recover with the tougher stuff.....

EDMO

[C5Engineer 1170]

So this is somewhat how my Bush Gear will look with just the wood fairings except I will do both legs and not use electrical tape to hold them on or whatever he has going there. This is the Highwing gear and one big thing that I just noticed was that their V piece where the Cabane struts attach is way shallower than the Airdale gear. I wonder if there was any reasoning behind that. They also use a 1 1/4 tube for the front leg.

 

[Av8r3400 1179]

Speaking with Lowell they have had several of the same type failures of their gear too...  They have even taken it off their plane.

 

I do think you are on to something, though, Joey.  The location of the "cross" in the middle of the spring struts has something to do with the situation.  If you look at the Kitfox designed cabine gear, their cross is much LOWER, and the gear splayed WIDER than either the Airdale or Highwing designs.  I have not heard of any failures on this design.

 

The other aspect of the problem is the travel of the suspension.  It will travel until the spring bottoms out.  When this happens it is a sudden stop.  Like hitting it with a hammer.  If there was a way to increase the travel then cushion the impact of the stop, I believe this would also help the design.

[C5Engineer 1170]

So this is somewhat how my Bush Gear will look with just the wood fairings except I will do both legs and not use electrical tape to hold them on or whatever he has going there. This is the Highwing gear and one big thing that I just noticed was that their V piece where the Cabane struts attach is way shallower than the Airdale gear. I wonder if there was any reasoning behind that. They also use a 1 1/4 tube for the front leg.

 

 

The Avid gear is quite a bit lower than the High Wing Gear...it looks pretty close to the Kitfox angles.

 

 

 

Larry here was the fix for the limited travel. It's supposed to have at least double the original.

 

[Av8r3400 1179]

The smaller lighter springs are what failed on my buddy's hybrid plane. The difference is when they bottom out, they bottom on the slots and hardware internally. I doubt the heavier spring ever bottomed on your light plane, Joey. They barely moved on his at 1200+ pounds.

Looking direct on the front of the Kitfox gear shows the angles to be much different.

What should happen is to stack the two springs together and double the travel of the assembly. IMO.

Edited 4 Jul 2013 by Av8r3400

[Av8r3400 1179]

Also, look at the difference in the gear leg of the Kitfox design. Much wider...

[wypaul 448]

Joey, do you have some pictures of your gear on the plane after they failed?  I've dropped mine in since the fuselage being beefed up without any problems.  There is no evidence of the springs bottoming out but maybe I will build a tattle-tale to see what the max movement is on a bounced landing.

[Av8r3400 1179]

I was always going to mount my video cam on the belly of my buddy's plane and do just that -- tattle tale the spring arms.

 

What beefing did you do?  Looking at the damage on his hybrid plane, I thought that if the bungee truss was webbed from side to side this would help a lot.  Maybe webbing the side trusses too.  

 

The trade off is the needed "beefing" would most likely out weigh the upgrade to Grove gear...

[wypaul 448]

Larry I guess I didn't take any photos but what I did was to install a 1/16" plate of 4130 at each end of the seat truss (about 4 x 6") and a small triangular piece of 4130 over the small triangular section of the floor area just ahead of the front gear leg attachment point. Also filled the first two triangular areas at each end of the seat truss and the mentioned small triangle with 1/4" plywood. Total weight of about 1.5-2.0 pounds. My guess is that with the bush gear and the beefing it still weighs about 15 lbs less than the Grove gear.

I am down to under 10 hours left in Phase I. Ventured out over the mountains today for a couple of hours early this morning.

 

How are the TW repairs coming on your plane. 

[Av8r3400 1179]

Tail wheel mod/repair is all good.  I added a third leaf to the spring to prevent sagging and poor caster angel induced shimmy.  It works like a dream.

 

I think a lot of people overestimate the weight gain from a Grove conversion.  My plane gained only something like 12 pounds.  But it also gained brakes that work, proven suspension, real aircraft wheels, wider track, less drag, ...

 

I would seriously consider putting the plywood triangles in every opening of the bungee truss.  Easy to do and a relatively light mod for considerable gain in strength.

 

If I were building one from the ground up and planning on this gear, I would do the entire bungee truss like I did my side trusses on the Mangy Fox.

[C5Engineer 1170]

The smaller lighter springs are what failed on my buddy's hybrid plane. The difference is when they bottom out, they bottom on the slots and hardware internally. I doubt the heavier spring ever bottomed on your light plane, Joey. They barely moved on his at 1200+ pounds.

Looking direct on the front of the Kitfox gear shows the angles to be much different.

What should happen is to stack the two springs together and double the travel of the assembly. IMO.

What's the difference between bottoming out and not having any travel to start with where it's basically the same as having a fixed gear? Those first batch of springs you could use under a vehicle and not bottom them out. If your pranging it on hard enough to be bottoming out springs it doesn't really matter what you have for gear...the key is to NOT prang it on. When my first set of gear failed I was landing a spot that most people wouldn't of tried to land on with an engine out. I'm not blaming the gear..I can what if it all day but the bottom line is my Cahones were bigger than my brain that day and got to join the club of those that have when I misjudged how steep that place was. Were comparing Apples to Oranges when you look at my flying compared to your average Kitfox/Avid driver. I'm sure the Grove works awesome for most folks. Seems every purpose built STOL airplane out there has some version of a cabane braced gear and all Cessnas have spring gear. I'm not Engineer but there's gotta be a reason for that.

 

Paul I will send you a PM to get your email. Don't want to publicly post pics of it...

[Av8r3400 1179]

I thought this photo may offer some thoughts.  A fat-assed, compensation machine, Super (duper) Cub at today's 68C fly-in.

 

Note that the "cross" is lower, making the "spring struts" bend downward.  I believe that this orientation spreads the load to both sides of the fuselage better than if the "spring struts" were straight or bent upward.

Edited 5 Jul 2013 by Av8r3400

[Av8r3400 1179]

What's the difference between bottoming out and not having any travel to start with where it's basically the same as having a fixed gear? 

 

The difference, Joey is like trying to push on a nail with a hammer or swinging the hammer and impacting the nail head.  The amount of force generated is much greater.

 

My friend, Dave, with the hybrid that wrecked two sets of these gear, used to own and fly a Piper Vagabond that did not have any suspension other than the tires.  (PA15 rather than a PA17 which is the same plane with bungees)  He told me he had dropped that plane, of similar weight and size, several times with as much if not greater force than what wrecked his gear the last time.  Our new Grove springs will be here on Monday!

 

...And Leni - You missed out on his better than new 150 hp Clipper (PA16).  It's sold to a guy from Hawaii.  He's planning on keeping it in Portland and flying it to Alaska.

[Bandit 286]

Wouldn't you rather bend the gear than the fuselage? How are people bending the Cabane gear? It seems like the old Mark4 gear had plenty of trouble also. I think some airplanes are built to heavy. Keep them simple and light. If I have enough runway I always add a little power right before touchdown. I try to fly it on the runway. There are times you do need to do a full stall landing on a short landing area, then I could see how you could land hard sometimes. If I have plenty of runway which I usually do, I use it if I have to.

[C5Engineer 1170]

 

 

Similar?

[Av8r3400 1179]

Look at the straight line your gear made versus the downward bend in the cub's gear.  The line I mean is from the axle to the opposite side longeron.   That's what I was trying to show.

 

A subtle difference, for sure.  But, engineering wise, very different in the flow of energy.

[C5Engineer 1170]

The Highwing gear has almost has a negative angle to it.

 

[C5Engineer 1170]

If you have a bad day in the end it doesn't really matter what kind of gear you have. This guy did substantial damage with Grove gear.

 

 

And it looks like he just wrecked his grove gear again...pretty crazy about that turtle deck. This is the third time I've heard of this happening recently.

 

[akflyer 1427]

The difference there Joey is that the grove gear gave way, but the fuse is not buckled..

 

The turtle deck issue is something else all together and was the reason for me being banned on the matronix site the first time

 

[C5Engineer 1170]

I agree with you guys I was just messing with Larry a little bit...sorry Larry  I'm curious what his plane would of looked like with stock gear under either of those two events. I'm sure it wouldn't of been pretty. Whats your guys thoughts on that turtle deck? I think I would of probably leaned towards shutting her down too if I still had runway in front of me. Not sure what caused the hard landing unless he was running out of room and basically forced it onto the ground. I've heard that not having that upper bearing on the flaperon can allow flaperon flutter to occur. Was that before or after they added counterweights? I guess if that were to happen inflight about all you could do is slow down and fly her nice and gentle to the nearest suitable landing spot. Don't think it would be a cause to panic and bend your plane though....thoughts??