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First Flights Completed! (gear leg question)

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ceengland7(at)gmail.com
Guest

Posted: Sun Oct 29, 2017 11:26 am Post subject: First Flights Completed! (gear leg question)

Looking at Richard's pics of gear legs; has anyone ever made a set of 

steel legs that don't have any taper? In the RV-x world, the Harmon 

Rockets use titanium legs with no taper, but supposedly, titanium's 

flexing characteristics are different enough from steel that they can 

get away with no taper. Making an axle adapter to fit the fatter leg 

cross section wouldn't be that big a deal, but I'm not sure about 

transferring extra impulse load directly into the gear sockets if using 

non-tapered gear.



Thanks,



Charlie



On 10/29/2017 12:52 PM, Richard Pike wrote:

 	  Quote: 	
		   



 Wait until Harbor Freight puts this on sale, fix it yourself.

 https://www.harborfreight.com/12-ton-hydraulic-pipe-bender-62539.html

 In the meanwhile, take the leg to any machine shop, they can straighten it for about $20 if it is not badly bent.



 Attached is my collection of old Firestar/FSII gear legs. The top set is from the original Firestar from which we built the FF clone, and I would consider them un-straightenable. The next 3 down all have slight bends and could easily be fixed with a press in just a few minutes. The bottom one is unbent.



 --------

 Richard Pike

 Kolb MKIII N420P (420ldPoops)

 Kingsport, TN 3TN0



 Forgiving is tough. Being forgiven is wonderful.





 Read this topic online here:



 http://forums.matronics.com/viewtopic.php?p=473937#473937





 Attachments:



 http://forums.matronics.com//files/p1060418_medium_140.jpg




	




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rascaljohn

Joined: 02 May 2013
Posts: 23

Posted: Sun Oct 29, 2017 11:59 am Post subject: First Flights Completed! (gear leg question)

Hello to fellow Kolb owners. Name is John from Northern California, just completed a FS ll and have been reading all your great comments about building and flying for about 2 yrs. while finishing my project.  I'll be asking for lots of advice. 

Listening in on the gear leg issue...I was wondering if any sort of bungee cord arrangement like those found on bush planes could absorb some hard landings, maybe a spring steel leg? ( Maybe steal the front shock struts off my wife's car)

Sent from my iP

 	  Quote: 	
		   On Oct 29, 2017, at 12:29 PM, Charlie England <ceengland7(at)gmail.com> wrote:

 Looking at Richard's pics of gear legs; has anyone ever made a set of steel legs that don't have any taper? In the RV-x world, the Harmon Rockets use titanium legs with no taper, but supposedly, titanium's flexing characteristics are different enough from steel that they can get away with no taper. Making an axle adapter to fit the fatter leg cross section wouldn't be that big a deal, but I'm not sure about transferring extra impulse load directly into the gear sockets if using non-tapered gear.

 Thanks,

 Charlie

> On 10/29/2017 12:52 PM, Richard Pike wrote:

> 

> 

> Wait until Harbor Freight puts this on sale, fix it yourself.

> https://www.harborfreight.com/12-ton-hydraulic-pipe-bender-62539.html

> In the meanwhile, take the leg to any machine shop, they can straighten it for about $20 if it is not badly bent.

> 

> Attached is my collection of old Firestar/FSII gear legs. The top set is from the original Firestar from which we built the FF clone, and I would consider them un-straightenable. The next 3 down all have slight bends and could easily be fixed with a press in just a few minutes. The bottom one is unbent.

> 

> --------

> Richard Pike

> Kolb MKIII N420P (420ldPoops)

> Kingsport, TN 3TN0

> 

> Forgiving is tough. Being forgiven is wonderful.

> 

> 

> 

> 

> Read this topic online here:

> 

> http://forums.matronics.com/viewtopic.php?p=473937#473937

> 

> 

> 

> 

> Attachments:

> 

> http://forums.matronics.com//files/p1060418_medium_140.jpg

> 

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John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Oct 29, 2017 12:34 pm Post subject: First Flights Completed! (gear leg question)

Yes, sir.  We have been flying Kolbs off heat treated 4130 steel legs for

more than 30 years.



john h

mkIII

Titus, Alabama





--

_________________
John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Oct 29, 2017 12:48 pm Post subject: First Flights Completed! (gear leg question)

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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

rascaljohn

Joined: 02 May 2013
Posts: 23

Posted: Sun Oct 29, 2017 12:49 pm Post subject: First Flights Completed! (gear leg question)

...So the aluminum legs will sooner or later become a lost cause?



Sent from my iPad



[quote] On Oct 29, 2017, at 1:33 PM, John Hauck <jhauck(at)elmore.rr.com> wrote:

 

 

 

 Yes, sir.  We have been flying Kolbs off heat treated 4130 steel legs for

 more than 30 years.

 

 john h

 mkIII

 Titus, Alabama

 

 

 

 

 --

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Sun Oct 29, 2017 2:03 pm Post subject: First Flights Completed! (gear leg question)

I think so.  The reason we "lost" 7075 alum legs 30 years ago.



john h

mkIII

Titus, Alabama





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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

ceengland7(at)gmail.com
Guest

Posted: Sun Oct 29, 2017 2:36 pm Post subject: First Flights Completed! (gear leg question)

Thanks, John, for both the info & the pics. Getting the nose (& wing 

angle of attack) up is the primary reason I was asking. Much easier to 

fab a set of legs without taper. I even looked at just making them 

longer, but to get any height benefit, they'd need to be quite a bit 

longer on the old Mk I; the angle is fairly shallow compared to the pics 

you posted.



BTW, any of you guys that are 'in the neighborhood' of Jackson MS next 

weekend are welcome to our annual Pumpkin Drop here at Slobovia 

Outernational (MS71). I sent a flyer to the list about a month ago, but 

if you missed it, just write me off-list for flying and/or driving 

directions. Early forecast is for rain, but we all know about forecasts. 



Charlie

ceengland7(at)gmail.com

On 10/29/2017 3:46 PM, John Hauck wrote:

[quote]

 --

RoHam

Joined: 05 Aug 2017
Posts: 11
Location: MA

Posted: Mon Oct 30, 2017 8:15 am Post subject: Re: First Flights Completed! (gear leg question)

A buddy of mine is trying this setup for off airport operation. Too much fabrication for me, but I like it. ...Bob

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victorbravo(at)sbcglobal.
Guest

Posted: Mon Oct 30, 2017 9:35 am Post subject: First Flights Completed! (gear leg question)

" A buddy of mine is trying this setup for off airport operation. Too much fabrication for me, but  I like it. ...Bob"



Fabrication???? There's a month's worth of ENGINEERING that has to be done on that setup long before the first piece of metal is cut  !



I am 1000% in favor of innovation and tinkering, but in cases like this where primary structure is involved the innovation has to be balanced with engineering done by someone with training. The exotic setup in that photo MAY BE really well done, and properly engineered. I have no idea if it is or not, and I am not quaified to say if it is engineered well. But I can say that there either has been, or has to be, a fair amount of analysis made on how those landing loads are put into the fuselage structure, and whether the FORWARD fuselage attachment can take those loads without bending the lower longerons or cross members. The REAR mounting ties in with the standard Kolb socket tube, so it is LIKELY OK. 



I hope it works, and I hope that the Super Cub tyle bungee arrangement delivers the result that is being pursued.



Reminds me, I owe the Kolb List a photo of two of my landing gear setup. I used the extra long steel legs from a Kolb Slingshot, and mounted a set of Desser 21 inch LSA bush tires. John H was right, I'll need a ladder to get in the darn thing ! I will actually have to make up some sort of step, or stirrup somewhere to get in it.



But it will give me a very high ground angle for the shortest possibe takeoff.



Bill Berle

FireStar 2 / HKS 700E (now in the engine wiring stage)

Los Angeles, CA

Dan Breitigam

Joined: 06 Apr 2011
Posts: 16

Posted: Fri Dec 08, 2017 5:06 am Post subject: Re: First Flights Completed! (gear leg question)

So do you guys think the aluminum gear legs on my Mk III Xtra will fail?  To gain a little height I inserted them so they are 4 inches out from what the plans say. Nervous about that. Haven’t flown this restoration project yet. 



Thanks!

Dan in Chattanooga

John Hauck

Joined: 09 Jan 2006
Posts: 4639
Location: Titus, Alabama (hauck's holler)

Posted: Fri Dec 08, 2017 7:40 am Post subject: First Flights Completed! (gear leg question)

There is a reason the plans call for inserting gear legs all the way into the gear leg sockets.  That is so the load will be carried by the entire socket.



By not inserting the gear leg all the way into the socket, a stress point is established at the end of the gear leg, a shearing effect.



Early Firestar plans called for centering the end of the gear leg at the mid-point of the gear leg socket.  When I crashed my FS on Grand Island, NY, summer of 1988, I sheared the gear leg socket right at the end of the gear leg.  On rebuild we started inserting the gear leg until it was seated all the way in the socket.



john h

mkIII

Titus, Alabama





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John Hauck
MKIII/912ULS
hauck's holler
Titus, Alabama

neilsenrm(at)gmail.com
Guest

Posted: Fri Dec 08, 2017 7:45 am Post subject: First Flights Completed! (gear leg question)

Dan

The aluminium gear legs are good and will protect your plane from damage from learning pilots up to a point. These legs don't spring and launch you back in the air like the steel legs which is good but they do bend. They also if installed like they were intended keep you on the ground till you have good flying air speed. By extending the gear legs you have become the test pilot. I do have a bit of concern for bending the steel tube in the fuselage that the aluminium gear slide into (landing gear socket) on a hard landing. Let us know how it works out.

I have the old style version 1.2 solid steel highly tapered very springy gear legs. They float over the roughest ground but are always waiting to spring me into the air with little airspeed from a botch landing.

Rick Neilsen

Redrive VW Powered MKIIIC

On Fri, Dec 8, 2017 at 8:06 AM, Dan Breitigam <dbrtgm(at)me.com (dbrtgm(at)me.com)> wrote:

 	  Quote: 	
		  --> Kolb-List message posted by: "Dan Breitigam" <dbrtgm(at)me.com (dbrtgm(at)me.com)>

 

 So do you guys think the aluminum gear legs on my Mk III Xtra will fail?  To gain a little height I inserted them so they are 4 inches out from what the plans say. Nervous about that. Haven’t flown this restoration project yet.

 

 Thanks!

 Dan in Chattanooga

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=476242#476242

 

 

 

 

 

 

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lcottrell

Joined: 29 May 2006
Posts: 1494
Location: Jordan Valley, Or

Posted: Fri Dec 08, 2017 8:25 am Post subject: First Flights Completed! (gear leg question)

See John's reply about the inserted length. As for the aluminum legs- if you are a very careful, skilled pilot who doesn't push the boundary's of you or your planes abilities, and stay on the airport tarmac, you can probably do quite well with the Alum legs. If you fly like I do, then you probably should consider steel. I have had three misfortunes with alum legs. All self inflicted you understand. 



Larry

On Fri, Dec 8, 2017 at 6:06 AM, Dan Breitigam <dbrtgm(at)me.com (dbrtgm(at)me.com)> wrote:

 	  Quote: 	
		  --> Kolb-List message posted by: "Dan Breitigam" <dbrtgm(at)me.com (dbrtgm(at)me.com)>

 

 So do you guys think the aluminum gear legs on my Mk III Xtra will fail?  To gain a little height I inserted them so they are 4 inches out from what the plans say. Nervous about that. Haven’t flown this restoration project yet.

 

 Thanks!

 Dan in Chattanooga

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=476242#476242

 

 

 

 

 

 

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Richard Pike

Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee

Posted: Fri Dec 08, 2017 11:52 am Post subject: Re: First Flights Completed! (gear leg question)

 	  RoHam wrote: 	
		  A buddy of mine is trying this setup for off airport operation. Too much fabrication for me, but I like it. ...Bob 	




I do not like it. The spreader bar attaches  to the New Extension well below the longeron and the original gear leg socket. Picture the side loads if you ever get that thing crossed up, or even worse, in a ground loop.

 

For example, you touch down while fighting a strong right crosswind, and maybe the nose swings right and the tail goes left. You begin a ground loop to the right.  With the normal gear, not a big deal. With this arrangement, the gear loads are transferred to the spreader bar, with the associated loads trying to pull the left New Extension under the belly, and push the right side New Extension up toward the underside of the wing.



I say this because this is very similar to how Jessie Anglin (mis) designed the spreader bar attachment brackets on the Anglin J-6 Karatoo - which kit I built - and which damaged the gear twice on a couple of landings where I got it sideways a bit, and then one day I was doing a touch and go and the left brake locked up. (My bad. The return valve in the master cylinder was not set properly) The airplane did a high speed ground loop to the left, the right main gear ended up under the left gear, the left main gear was up against the left wing strut. Check the pictures... Not a smiley face day.



Got an engineer friend to look at the plans and how it was originally built, and his response was "Well, no damm wonder..." He redesigned it to get everything aligned, I spent the winter rebuilding it, and the next time it ground looped, it was a non-event. (aside from the laughs of the watchers)



The attachment points for the spreader bar need to be in alignment with the lower longeron so that they cannot exert any twisting moment to anything. The loads need to be transmitted directly. 



Looking at the picture, the attach points for the spreader bar need to be in line between the clevis pin hole for the lift strut and the opposite axle shock strut point attach to make it non-twisty, which means brackets welded to the lower cross bar of the landing gear A-Frame about an inch or so inside the longeron and tied into the main landing gear tube.



And for Dan; the reason those gear legs are supposed to go all the way up to the top as far as possible - if you drop it in hard enough, the gear legs will kink the tube they are inserted in. The early Firestars had legs that only went a bit beyond the retaining bolt hole; after enough guys kinked that socket tube, Kolb started making the gear legs longer. So if you have slid the gear legs down about 4 inches, you can take a magic marker and put a mark on the side of the tube where the gear leg tops out. When the day comes that you drop it in, that is where the kink will be.



Sorry to be the list wet blanket, but that's how I see it.

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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0

Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing.

byoungplumbing(at)gmail.c
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Posted: Fri Dec 08, 2017 12:56 pm Post subject: First Flights Completed! (gear leg question)

They will last till you have a hard landing,   when they give way and bend it should do so without damaging the cage,  provided they are installed to plans.   



Boyd Young

On Dec 8, 2017 6:09 AM, "Dan Breitigam" <dbrtgm(at)me.com (dbrtgm(at)me.com)> wrote: 	  Quote: 	
		  --> Kolb-List message posted by: "Dan Breitigam" <dbrtgm(at)me.com (dbrtgm(at)me.com)>

 

 So do you guys think the aluminum gear legs on my Mk III Xtra will fail?  To gain a little height I inserted them so they are 4 inches out from what the plans say. Nervous about that. Haven’t flown this restoration project yet.

 

 Thanks!

 Dan in Chattanooga

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=476242#476242

 

 

 

 

 

 

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Dan Breitigam

Joined: 06 Apr 2011
Posts: 16

Posted: Fri Dec 08, 2017 1:55 pm Post subject: Re: First Flights Completed! (gear leg question)

Thanks to those who spoke of the gear leg socket not holding up.  I will heed that advice and shove it in the rest of the way!



-Dan

victorbravo(at)sbcglobal.
Guest

Posted: Fri Dec 08, 2017 2:12 pm Post subject: First Flights Completed! (gear leg question)

I am definitely the LEAST "expert" on this group, but I have to agree that common sense and basic engineering favors having the gear leg inserted further into the socket.



More than one Kolb List  participant has plenty of experience with this question, and more than one has installed different gear, longer gear, switched between aluminum and steel, etc. Their advice will be worth listening to.



In pursuit of the shortest possible takeoff roll, I installed a much longer gear on my Firestar. But this has created significant extra risk, and I have to accept that. I have not flown the aircraft yet, so I cannot provide any factual information.



Bill Berle

www.ezflaphandle.com  - safety & performance upgrade for light aircraft

www.grantstar.net           - winning proposals for non-profit and for-profit entities



--------------------------------------------

On Fri, 12/8/17, Dan Breitigam <dbrtgm(at)me.com> wrote:



 Subject: Re: First Flights Completed! (gear leg question)

 To: kolb-list(at)matronics.com

 Date: Friday, December 8, 2017, 1:55 PM

 

 

 Breitigam" <dbrtgm(at)me.com>

 

 Thanks to those who spoke of the gear

 leg socket not holding up.  I will heed that advice and

 shove it in the rest of the way!

 

 -Dan

 

 

 

 

 Read this topic online here:

 

 http://forums.matronics.com/viewtopic.php?p=476256#476256

 

 

 

 

 

 

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