strulag

My Feedback: (-1)

What's the strongest wood out there? I need to redo my landing gear on my Funtana. It's for the block that the landing gear is attached to.

Ernie Misner

I think I'd use aircraft ply, or perhaps a couple layers of thin ply epoxied together. The trick though is to tie it into the fuse a little more the the front or back, spreading the stresses out instead of all in one short spot.

Interestingly, you can tap threads right into the wood for nylon bolts and stiffen them with thin CA if you want to get away from the blind nuts.

Ernie

da Rock

Oak. And you can buy relatively thin strips of it at your local home improvement warehouse. I'm not kidding.
I think 1/4" is the thinnest they sell. It's quite useful for the really big and heavy models. Laminate it with some type of lighter material and it's excellent. It'll take just about any abuse and the backing spreads out the shock. However, I don't know of many Funtana's that're big and heavy enough that you'd need it.

65 Chevy

My Feedback: (1)

I have had my best luck with thin Maple. Also available at most Lumber Yards in 1/4" thick. I laminate with thin balsa (1/16", 3/32") to get the thickness I need. More Layers = better. The nice thing about Maple is the very fine grain. You can tap it for threads very nicely. It works much better than Oak for tapping. Best of all, is you really done have to CA the threads and retap. Just cut the threads with your favorite tap, and you're done

soarrich

My Feedback: (98)

Like 65 Chevy said, Maple is what they use for motor mounts, good stuff, cheap at HomeDepot, but like darock said you've got to spread the loads out to the sides of the fuse, good aircraft ply doublers on the sides will do that.

rclement

My Feedback: (1)

Like Ernie said, you need to spread the stresses out to the fuse to distribute the load. I kept the stock landing block on my Funtana 40 and beefed it up with Gorilla glue and put some of the glue all around it and up the fuse sides. I added and extra "T" nut and replaced the bolts with nylon ones and also replaced the landing gear with a Dubro set. It actually looks pretty good and after a few less than stellar landings it just snapped the nylon screws off and did no damage at all. The Dubro gear seems to give it a bit more spring like a shock absorber. I don't think that the aluminum gear that comes with most planes is the way to go and I doubt that the manufactures spend a whole lot of time to heat treat the aluminum correctly so it's either too soft or too stiff. I had some trouble with the gear on an OMP Katana profile. It bent like used spagetti so I had the aluminum hardness tested and it turned out to be 6064 T4. That's wayyyyy too soft to be of much use for landing gear. (IMO)

strulag

My Feedback: (-1)

Did you guys ever use poplar? That's what I used last time which I got from HomeDepot. Doubled a 1/4 thich board except that I didn't glue the 2 pieces together so it was the strength of just one (I used the 2nd layer just for the spacing I needed). How does this comapre to maple since I already have the poplar. If the maple is better I'll just go buy some at Home Depot.

Also what's the best glue? Is polyurethane that much stronger than 30min epoxy?

da Rock

The maple is probably the best for weight versus strength however........

Most wood varies quite a bit in strength and density. The heavier woods like oak vary less, the lighter woods like maple vary more. So you need to look carefully at whatever you buy.

There is also something not mentioned yet that's just about perfect. It's quality plywood. There are thousands of grades and you usually just stumble onto the appropriate kind, but it's a good idea to keep an eye out for it. I found some in Lowes Home Improvement a year or so ago. It was oak plywood that looked like it was being marketed as a premium plywood. For what, I got no clue, because most people who seek out high quality plywood aren't usually heading to Lowes for it.

It actually seemed to have one exterior ply veneer in straight grain cut at a slight angle (to give a good finished oak grain) and the other side was close to C-grain. It appeared to be a type that the furniture factories would have used. What it was doing in Lowes remains a mystery. I've seen good plywood since, but not that stuff.

It was 5 ply and only 1/4" thick. I got a sheet and have been using it down ever since.

It's often of very little value to laminate a plate that's just going to hold T-nuts for landing gear. You really don't need thickness, you need strength. And since flat gear blanks already spread out the force well, having excess strength in thickness is wasted. You really do need support at the sides of the plate, not in the plate itself. What works best are perpendicular side formers and they can be lightply.

Best glue? Epoxy is excellent. Don't glop it on. Wipe the plate to get total coverage and wipe whatever it's being glued to to get total coverage and clamp. Epoxy does best when it's just there to bond together the two parts, not fill holes.

CA however, is just as excellent and has the added benefit of penetrating the softer woods and turning them into very strong components. It's often a trick however to get the parts together properly. The slower CAs are the best for landing gear support plates that're laminated into something else.

da Rock

Poplar is excellent too. It's more than strong enough for the smaller models. It's also a very "straight" and uniform wood. I've ripped many a stick to use to stiffen a built up horizontal stab or vertical stab (to stand up to flip overs). It's light enough to use anywhere and strong enough to really be of value as a stiffiner.

Keep in mind that any of the very heavy woods will be more than strong enough even if you drill lightening holes around the non-critical areas. And drilling lightening holes in things like wing joiners actually helps give you a secure glue job in tight fitting slots etc. The glue that gets squeezed into those holes as the joiner is pushed into it's slot gets carried into the slot and will then usually wind up "wicking" to the slot wood, giving adequate gluing where glue is often wiped away from.

strulag

My Feedback: (-1)

Well, I went to Home Depot today and only found oak and poplar. I bought that 1/2 in because I need the thickness for the landing gear to clear the fuse. Man that oak waaaaay heavier than the poplar. What would you guys recomend between the 2? I guess it would not make that big of a difference when you cut them down to just a few inches.

I don't know what you guys are talking about the reinforcing and distributing the load. The F90 doesn't have much down there, I don't know if there are many options. I already have something on the inside of the fuse which holds the tank.

da Rock

That 1/2" oak is going to be way too heavy and it's strength is wasted too. You can drill it full of holes to lighten it however. But use the poplar. It will be strong enough at that thickness.

The block that's already in the airplane that the gear is attached to is attached to the sides, right? If you strengthen the block, the sides will still be the weak link. Your bulletproof gear plate will now simply destroy the fuselage sides instead of breaking themselves.

After you replace the broken plate with your new plate, make up some fuselage side doublers that are glued to the fuselage sides and that brace the new gear plate. They can be lightply. Or you can also CA some glass cloth around the fuselage sides and onto the plate. Do all this reinforcing inside the fuselage of course. It actually won't take much.

A lot of the Chinese ARFs I've seen this last year are coming over here with some kind of stringy wood in the plywood gear support plates. Very often, they're weaker than any plywood you might find in the LHS that's the same thickness. However, that stringy wood will suck up a bunch of CA and greatly increase in strength. Some of their lightply is also stringy and almost worthless unless CA'd.

We learn from our crashes. And from our bad landings. Whenever you have the opportunity, look hard at the damaged parts. If the plane is going to be a writeoff anyway, go ahead and test it's remaining structure with your hands. You'll learn a lot trying to pull things apart with your hands. You'll learn just how strong or weak that stringy plywood is. I learned the other day that hinge glued Dubro hinges are ABSOLUTELY NOT going to come out. And I felt exactly how lame that Asian plywood is when it's untreated. I would almost suggest that it's a Commie plot to make us have to buy ARFs more frequently! grin..... or maybe not..... but it's stupid for them to be selling decently constructed ARFs with such low grade ply in them. They're cutting their own throats while they're cutting ours.

strulag

My Feedback: (-1)

Thx for your help darock. I'll go ahead and do the poplar then and see what happens. I never had the problem of the tristock that's holding the gearplate ripping off. I don't have much experience with this so I don't know how to gauge the strength I need on the landing gear. I hear it's not good to make it rock solid either because then you'll rip the whole fuse apart and I don't want to do that. I guess I'll have to wait and see

da Rock

Sounds like you're good to go.

You're the mechanic under the airplane. It's sensible that you make the call.

The idea about making the mount too strong..... I think some other guys mentioned using nylon bolts to hold the gear to the airplane. The idea sort of goes along with "making the mount too strong". sort of....
The landing gear system is from the tires to the fuselage. And you've discovered that the weak link in that system was the original mounting plate. Making it stronger is definitely needed. And that has already been proven. So now after putting in the stronger support into the system, you ought to be able to land harder than before. Kewl....

But someday you might land harder than the new and improved system can stand. And no way to predict how hard that's gonna be. And certainly no way to build a totally bulletproof system. So what some guys do is use nylon bolts to bolt on the aluminum gear to the underside of the fuselage. The bolts will be strong enough to stand up to any fairly decent landing and have proven over the years to be weak enough to pop on the landings that would have pulled out the gear plate from the fuselage.

It takes a small amount of work to retrofit any new airplane to have nylon gear bolts. You can simply knock out the original Tnuts, drill the existing holes out, and put 1/4x20 Tnuts into the bigger holes in the fuselage. Simple to do and quick. Costs something like $2.50 or $3.00 if you get the nuts and bolts at Lowes. And all you gotta have for tools is a drill and bit. And you can do it anytime you feel like doing it. I whipped together an UltraStick40 a couple of weeks ago and flown it 10-12 times so far. Will do the retrofit tonight. Got nothing else I want to do, so that job will be perfect to accomplish something worthwhile. But that's what the guys who were mentioning nylon bolts were saying........

Ernie Misner

Darock, how's the US 40 fly? I have an older one that doesn't have the balanced rudder. It pitches UP something terrible with rudder inputs. I think it might be from the strong triangular shape of the rudder and no balance on the top...? The must have changed it for a reason.

On the subject of replacing metal bolts with nylon, I discovered on my Ultra Stick 60, that it came with 8-32 metal bolts for the gear, and that I could simply drill out the T nuts a bit and retap them with 10-32 threads for nylon bolts. There is just enough metal there and it is soft. I did add one 1/4-20 nylon bolt between them though and tapped the threads right into the wood.

Ernie

da Rock

It's the new balanced rudder design. And the rudder still pitches it but not very badly. What that rudder does with a vengence is roll the sucker. Try to go into a knife edge and the sucker does a roll just about as quickly as it'll do a roll with ailerons. I've diddled with my JR8103 TX and put some mix into the rudder-ailerons to cut the roll couple down some. If the thing had been a 2-channel glider, it could have saved you a servo. You could have left out the elevator servo and simply turned the thing with just the rudder. It would pitch up and roll into any turn you wanted with just the rudder.

I wish I could see yours fly. Or you could see mine fly. Then we'd have a better feel for what that balanced rudder is doing. But it sounds to me like it didn't do much. As long as it is, I'd bet that it stalls with just about every rudder input. I actually considered cutting it off and gluing it to the top of the fin.... ..... back when I assembled the 2nd one, just to see if the airplane didn't fly better. Funny that it was made both ways. Wish I knew what they were thinking. Wonder if the Ugly Sticks rudder>pitch/roll like the UltraSticks?

Does your's whistle? Both of mine whistle like crazy. Well, the first one whistled more than this new one, but the new one ain't exactly silent.

NM2K

My Feedback: (14)

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I cut my landing gear blocks out of a 2x4 or 1x3 (pine). It works perfectly, is light, inexpensive and is readily available. A used Dremel tablesaw will allow you to make as many as you'll ever need, plus you can vary the slot all you want.