Landing gear style

[Matt Piatkowski]

Hello,
The wings mounted landing gear for large plane ( 60" wings span, ~64 oz. RTF estimated weight ), made of 0.157" dia. wire, with 2" foam wheels adds almost 5 oz. of weight. Included in this 5 oz. are the hardwood mounting blocks, wheels collars, wire securing nylon brackets with screws, plywood ribs doublers and epoxy.

The fuselage mounted aluminum landing gear for the same plane (0.090" AL) with 2" foam wheels, axles, wheels collars and mounting screws adds 3.2 oz.

The fuselage mounted carbon composite landing gear for the same plane with 2" foam wheels, axles, wheels collars and mounting screws adds 2.1 oz.

When small glass fibre or carbon composite pants are added, the final weight of these landing gear assemblies goes up by the same amount.

Having in mind the importance of weight of the finished competition stunt plane, the choice is obvious.

It would be interesting to know how many top pilots still use the wings mounted landing gear.

Thank you for your comments,
M

[Steve Helmick]

Do some more research on LG technology. Resinger, Cox, Haverly and Walker are using plug-in CF wing mounted LG struts derived from the Yatsenko's methodology. While the Yatsenkos use (or used) Titanium struts, there is a weight saving with the CF struts. Likely cheaper and easier to make, too. A search might show up the posts and pictures.

However, I have not seen an improvement in landings resulting from this. My theory is that if you can do perfect landings, they work, but if you muff a landing, it will be much worse than either a wing/wire or fuselage/aluminum gear. I have heard a few outbursts of colorful words after a botched landing, blaming the CF struts. As a fisherman familiar with high zoot CF fishing rods and low zoot FG rods, I think there is a similarity, and believe composite LG's need some more R&D to soften their energy absorption and release (somebody will be along shortly to correct the terminology). 

And I think 1/8" wire would be plenty adequate for a .60 sized stunter. A lot of the stiffness depends on the length of the torsion bar section...might take a bit of experimenting to get it right. Mike told me that his balsa/plywood wheel trousers are lighter than the CF ones. I have CF wheel panties on my Eagle, and have found them to be fairly fragile and easily damaged by botched landings. I'm a fan of wing mounted gears and "LG Doors" instead of wheel pants. Personally, I think they look better. If added to 1/8 wire, they could improve stiffness if you wish, or not, if you don't...depending on how you go about it.    Steve

[Dave_Trible]

I prefer wing mounted gear for ground handling and better landing scores, provided the screwball at the end of the lines doesn't mess up.  On my airplanes there is a weight penalty of about 2 ounces or more for the wing gear but a trade I'll take most of the time.  My take-apart airplane has fuselage mounted gear to offset some weight elsewhere but is more noticeably 'twangy' rolling on turf and slower to get off.  I'm thinking to try some wheel toe-in to help that.

[Dave_Trible]

Wing gear

[Dave_Trible]

Fuse gear 5/32 wire

[M Spencer]

with 2" foam wheels adds almost 5 oz. of weight.

 
Balderdash .

Think it was about 3 1/4 complete , 2 1/2 light dubro things , 1/8 lower wire ( unsprung ) 5/32 upper ( in wing ) wire. plus another 5 or 10 grammes for solder & copper binding .( once the wings finished )



The problem with wing gear , is if the Earth Shifts & smites the plane a mighty blow . . . . , whereas a Fuse Gear the wing might not fall off , in the same circumstances .

However for those that never crash & have bowling greens or billard tables to fly on , a wide gear track can be advantageous , as it sticks to the deck when one wheels down , particularly with Trike set up .

Theyre Split Pin / Cotter Pin retainers , just brass washers on opposite side lightest . Leave Cross Arm unepoxied , for torsion bar . Stake And Cold Chisel pins to washer , then cut ears to 1/4 " .
Preferably before installing . . .
You stake em 45 Deg , trim , the whack flat . Good Vise Grips to pull em taut . &/or Sit On Block - end of stick in vice  ( if stakeing in wing  )
Tend to have a suport over rear so the dont ( the mounts ) knock loose . & maybe 1/4 Sq across under front or suchlike .
High Speed on rough field's trying to rotate mount .

[Matt Piatkowski]

Hello,

The summary of your opinions:

1. Wings mounted L.G with wire:  advantage:       better landing on smooth surfaces when pilot can land well.
                                                  disadvantage:  heavier than the fuselage mounted gear and difficult to repair if something fails.

Weight savings from smaller wire diameter and shorter L.G. legs are of course possible but they are closely related to the potential shimmy problems and the propeller clearance issues. I would always select slightly larger wire diameter to avoid shimmy and slightly longer "legs" to have a bit more propeller clearance in case of rough surface take-offs.

Hi Matt Spencer,
Your design is simply different than the one I have described in my initial message: there are no torsion carrying parts of the L.G. wires and no grooved hardwood blocks that support these wires therefore your design is lighter, simpler but also less forgiving.

2. Wings mounted L.G with the carbon composite removable struts - Yatsenko style: I will do the research as suggested by Steve and check the details of the Yatsenko design.

Has anybody ever tried the aluminum removable struts in such gear?

3. Fuselage mounted L.G. with aluminum, carbon composite or/and wire struts (legs): more forgiving, better for use on rougher surfaces and used by more stunt fliers.

I am purposely ignoring the cost in this summary. If money is the issue the steel wire struts (legs), either for the wings mounted or the fuse mounted L.G. win.

I am waiting for more opinions, comments and ideas,

Happy Holidays,
M

[Paul Smith]

I favor the WING gear for many reasons.

One significant benefit is getting LG out of the engine & tank area.  It allows me to optimize the engine room without compromising for the LG.

The wish bone style of gear tends to spread out, unless built VERY stout.  Thus a fuse gear is a weight penalty.

[Gerald Arana]

Wing gear

And your point is.................

Jerry

[Gerald Arana]

Fuse gear 5/32 wire

Oh. I'll go with this one!

Jerry

[Peter Nevai]

What ever came in the kit box.

[Howard Rush]

First picture below is gear with a pipe hump, axles, and wheels: 2.3 oz.  A stress man (name withheld) wanted some lighter gear (second picture) for his electric stunter.  As shown with cowl latch, but no axles or wheels, it weighs 1.6 oz. I use these, but the stress man thinks they're too springy and has gone to wing-mounted gear.

[M Spencer]

Seems to use a triple nose rib , one 1.5 mm ( 1/16 th in.)  plywood .

Dural is heavier but togher than alumn.

Gear legs bolt on , unbolt for traveling .

[Igor Burger]

but the stress man thinks they're too springy and has gone to wing-mounted gear.

Too springy also for WCh contests? :-P

Fuselage mounted duraluminum LG has one advantage - it will survive also hard landings (read crash :- P ) while carbon LG will break, but carbon can be still done strong enought. I had also problems that they were too springy (read soft for the weight) when we did copy 1:1 until we did airfoiled crosssection thicker in middle ... now I use them with good results :- ))

[Brett Buck]

Too springy also for WCh contests? :-P

       I think he probably means standard contests - where the takeoff and landing count for the same as the square 8, and we aren't flying it out of a "potato field" (as Serge put it). For FAI/WC, even though it irritates me in every other case, even I would probably want to use fuse-mounted gear, and pretty soft at that. At least when you tear it out, it's just the fuselage.

     If Howard would start making his gear with a "hump" in the middle (so you can have it go over the pipe instead of under), it would be something I might use.

     Brett

[Howard Rush]

If Howard would start making his gear with a "hump" in the middle (so you can have it go over the pipe instead of under), it would be something I might use.

He did.  You missed the boat.  I might make some more.  Meanwhile, you might talk David out of some.

[Brett Buck]

He did.  You missed the boat.  I might make some more.  Meanwhile, you might talk David out of some.

   I have missed *a lot* of boats in recent years.

    Brett

[Howard Rush]

I had also problems that they were too springy (read soft for the weight) when we did copy 1:1 until we did airfoiled crosssection thicker in middle ... now I use them with good results :- ))

I use prepreg cooked in an oven.  For the same thickness as aluminium, carbon is lighter and maybe stiffer, particularly if one uses high modulus stuff.  It's a lot easier to make the prepreg stuff flat than airfoiled.  A guy who can make hollow props should be able to make hollow landing gear, but he may not want to use them in WCh potato fields.

[Tim Wescott]

I use these, but the stress man thinks they're too springy and has gone to wing-mounted gear.

Clearly you need to re-do with an outer layer of something dissipative, or perhaps with the thing separated into leaves that rub against one another.

For, you know, high-tech shock absorption, like you get from these:

[Igor Burger]

may not want to use them in WCh potato fields.

Well, I am OK like it is now, it nicely absorbs all bumps and rocks and model nicely glides over. It also works well on "standard" small local contests with perfect surface. And lately I also solved problem of too good surface like that in Bulgaria/Pazardzhik when models jumped all the way because surface was glass smooth ... wheels are angled to the center of circle to negate nose out position, so previose Ech in Pazardzhik I did not use sand on place where I started and landed like we used on Wch before :- ))

[Paul Walker]

For an ADVANCED class flier like yourself, the fuse mounted gear will do just fine for you.

Don't wast your time, and weight, on 5/32 piano wire wing mounted LG.

[M Spencer]

Just One More .

TThis James Young Bellanca . ( was a V tail one F S too . ) and the Bjornwall P-51 both use replacing a rib with a identical ply one ,
With the gear leg attacked , via J bolts or whatever .



Useing the split pin method , I soak the meatal pieces in acetone . Pre Tin the lower leg / solder - if its going to be fitted later .
Use Epoxy on the holes washers etc , and a small dab at the ' split ' pin . Last one I economised , a good blob there,
but minimalist everywhere .
ALSO,
The End of the L G Wire thru the ply ( rib / mount/whatever ) Good Clout in the vive, overlength . Fit on ply, clout , Scribe Cut .
And out with the disc grinder .  ( remove the leg & hold in the vise though . ) or cut & file/ dress .
As steels heavy its worth minimaliseing the quantity ,

The Soldered On lower leg , ( Throw the plane upside down , cover with old towel or whatever , Damp paper towel abot leg/wing )
easier to sheet.
Fouls less obstacles .
Adjustable hight .
Might Knock the lower leg/ whell off , to absorb impact , perhaps . ( I use 60/40 hard solder , thread of ex elec cord copper wire to bind )
likely better for knocking free with soft ( 50/50 ) solder . And not to much at that .

The Mew Gull I solderd saddles / stirrups to a aft bent main leg , hard solder . appear to hold up . Phospherous flux , 80 Wt lectricians Iron .
pre tin it all , in & out fast , or in steps , so leg inside wing dont get hot & bothered .

Trike Gear Platforms aft of spar , can be ' knock out ' with a bit of thought . keep em an inch clear of spar & t e tho , if you do .