Timber 110" Twin Build

[AKNick]

I've been very happy with the Dubro 2.5" smooth rubber low bounce tire as a tailwheel. It has the perfect amount of give and does exactly what Dubro claims with the "low bounce" description. The setup works awesome!

What do you think of the factory tail spring? Should I stick with it for beach flying and mill a tailwheel fork?

The Timber Tail is a lot heavier. I originally made a TW fork with a 2.25" sullivan tire and it sank in the sand, it pivoted great though. Your beach sand is a lot more compacted than mine close to the water. I really like the 3.25" Dubro smooth rubber low bounce on mine for this reason. I had bent up a 5/32" wire like yours and never really liked how it pivoted with a new design I came up with. I have debated making bearings for it to castor easier but was just a lot of work at the time so decided to stick with the stock spring. My geometry was probably all wrong though.
For the time being I am happy with the configuration that mine is in currently with the stock tailgear, and my 3.25" TW assy.
Did your tailgear come with three or two leafs? @Snoopy1 had only two - they sent him another and it also had two. Mine was an earlier production run and had three.
I like your setup a lot, If you can re-draw it up for a 3-3.5" wheel assy I think you'll be happier. the 3" and 3.25" share the same hub diameter. OR if you don't have access to a 3D Printer and want to play with my design, let me know. I can whistle one up for you.

 

[RC80AK]

The Timber Tail is a lot heavier. I originally made a TW fork with a 2.25" sullivan tire and it sank in the sand, it pivoted great though. Your beach sand is a lot more compacted than mine close to the water. I really like the 3.25" Dubro smooth rubber low bounce on mine for this reason. I had bent up a 5/32" wire like yours and never really liked how it pivoted with a new design I came up with. I have debated making bearings for it to castor easier but was just a lot of work at the time so decided to stick with the stock spring. My geometry was probably all wrong though.
For the time being I am happy with the configuration that mine is in currently with the stock tailgear, and my 3.25" TW assy.
Did your tailgear come with three or two leafs? @Snoopy1 had only two - they sent him another and it also had two. Mine was an earlier production run and had three.
I like your setup a lot, If you can re-draw it up for a 3-3.5" wheel assy I think you'll be happier. the 3" and 3.25" share the same hub diameter. OR if you don't have access to a 3D Printer and want to play with my design, let me know. I can whistle one up for you.

Excellent, thanks for the info! We fly in very similar places... I'll go with at least a 3.25" They included two leaf springs in my kit. I had to do some head scratching and tweaking on my fork to figure out how to machine it out of the 1" HDPE sheet I had. It was milled top down with some alignment holes and then rolled on its side and profiled. What CAD file format is your fork in? Do you recall how wide the 3.25" dubro is? I need to go dig through my old tire stash, maybe there's one from my dad's RC flying days. (small world - he flew a ton of RC in Juneau early 80s) I was born in Juneau and lived on Chichagof Island through 4th grade.

She arrived!!! I have a funny tradition of unboxing and plugging my planes together on the kitchen counter... I'm not a huge fan of the red and yellow together, but the finish/build quality is fantastic. A notch above my other H9 planes.

 

[AKNick]

Excellent, thanks for the info! We fly in very similar places... I'll go with at least a 3.25" They included two leaf springs in my kit. I had to do some head scratching and tweaking on my fork to figure out how to machine it out of the 1" HDPE sheet I had. It was milled top down with some alignment holes and then rolled on its side and profiled. What CAD file format is your fork in? Do you recall how wide the 3.25" dubro is? I need to go dig through my old tire stash, maybe there's one from my dad's RC flying days. (small world - he flew a ton of RC in Juneau early 80s) I was born in Juneau and lived on Chichagof Island through 4th grade.

She arrived!!! I have a funny tradition of unboxing and plugging my planes together on the kitchen counter... I'm not a huge fan of the red and yellow together, but the finish/build quality is fantastic. A notch above my other H9 planes.
View attachment 115202

Very nice! Your wife seems to be smiling so that's GREAT!!!! My TW fork is on Thingiverse as a .STL , not sure what the actual raw file is labeled. I'll have to check the diameter later.

 

[RC80AK]

Very nice! Your wife seems to be smiling so that's GREAT!!!! My TW fork is on Thingiverse as a .STL , not sure what the actual raw file is labeled. I'll have to check the diameter later.

Ellie got her pilots license right out of high school and is a big fan of all things aviation. My problem is that means all regulation of the RC addiction is solely up to me!

 

[RC80AK]

I tackled replacing the ridiculous H9 gear today. I was limited in gear width by the fuselage slot so I went with 1/4" 6061-T6 and narrowed the profile towards the axles. If it is over sprung once I get the plane to flight weight I'll belt sand a taper in the trailing edge of the gear. The gear legs are extended and swept forward for better handling in soft sand. On to the tail wheel fork!

 

[Snoopy1]

Very nicely done. Ok how do I place an order with you for one of those for my Timber. Still have the standard gear and it is continually spreading, and I do not want to install the cub gear. Like the look of the standard gear.

 

[RC80AK]

Very nicely done. Ok how do I place an order with you for one of those for my Timber. Still have the standard gear and it is continually spreading, and I do not want to install the cub gear. Like the look of the standard gear.

Thanks Snoopy1, I cant figure out that stock gear??? It's not even close for a plane this size. I like the looks of spring gear on this airframe as well. 6061-T6 gear works great for rough terrain in combination with 6" Dubro low bounce tires. I might be able to make up a couple sets once I beat these up a bit to make sure they are the right size. The cub style gear is braced better for very hard hits, but looking inside the Timber they have some decent aluminum angle bracing on the spring mount point. Even with hard foam tires my little 60" Ultra Swizzle takes rocks and bumps nicely with 1/8" thick 6061 landing gear.

 

[RC80AK]

Here's a quick screen shot of my gear dimensions. Take in to account these haven't been flown yet. It's at least a reference if someone wants to make their own. Heat the aluminum with a propane torch until it begins to soften and bend easier. No heat = cracking. Let the aluminum cool down at room temp, the bending/cooling harden it back up. A 3"x30" 6061-T6 aluminum flat bar is just large enough. 3/16 would work if you ad a little material towards the axles. If you don't want your axles further forward than stock make the leading edge straight rather than swept forward.

 

[Snoopy1]

Here's a quick screen shot of my gear dimensions. Take in to account these haven't been flown yet. It's at least a reference if someone wants to make their own. Heat the aluminum with a propane torch until it begins to soften and bend easier. No heat = cracking. Let the aluminum cool down at room temp, the bending/cooling harden it back up. A 3"x30" 6061-T6 aluminum flat bar is just large enough. 3/16 would work if you ad a little material towards the axles. If you don't want your axles further forward than stock make the leading edge straight rather than swept forward.
View attachment 115218 View attachment 115219

Looks great thanks for the drawing, have a couple of questions did you make the legs a little longer for prop clearance. Second one when you heat the aluminum to bend it do just let it cool back down or do some kind of heat treatment get back to what it was.
Like the bending jig you made that must make bending gear a lot better. The last time I tried to bend 1/4 gear I chased it all across the shop trying hold onto it and bend it. Never got the bends nice and square.

 

[RC80AK]

Looks great thanks for the drawing, have a couple of questions did you make the legs a little longer for prop clearance. Second one when you heat the aluminum to bend it do just let it cool back down or do some kind of heat treatment get back to what it was.
Like the bending jig you made that must make bending gear a lot better. The last time I tried to bend 1/4 gear I chased it all across the shop trying hold onto it and bend it. Never got the bends nice and square.

I'll be swinging two 16" props so it's more an issue of appearance, width, and a higher angle of attack in three point. I fly in high winds quite a bit and need a wider stance with those long 110" wings. Pushing the axles forward just helps keep the tail down in rutted, soft beach sand. It can make it a little more squirrely, but having a good tailwheel setup with expo dialed in calms those issues down.

The factory gear are more like 1.5" wide and there is room left in the slot. The gear also is closer to 1/8" thick. If you fill the slot, bump the upper width to 1.6", and don't extend it as far I think 3/16" would be much better. I went 1/4" with the long legs, and added weight from the planned mods. If you don't sweep forward a 2" wide piece of flat bar would work, and it would be much easier to cut out with the leading edge being straight.

6061-T6 will start to fatigue and often crack when you attempt a 45deg bend. It's also quite difficult to bend cold. I heat it up around 20 seconds before starting the bend and usually a little heat through the bending process. The heat softens it up significantly. My experience is the heat softens it just enough to move without cracking, the bend work hardens the material a little, and then letting it cool slowly the area hardens back up. So no heat treating other than warming it to form.

The bending brake is a contraption I built just out of high school to make some wing attach fittings on a full size plane. It isn't pretty, but I've made a ton of RC gear on it! It's more difficult to do in a vice. You can use two larger crescent wrenches, one angled in from either side, right up to your bend line. Sweeping the gear forward makes it harder to get the bends square, if you don't need the axles forward keep the leading edge straight for ease of fabrication.