Tweet
This is a video I had wanted to include with the above review, but couldn't initially due to technical difficulties. That's almost like "it's in the mail" but not quite".
-
-
That steering is really something!
Any guesses as to the ground speed you are touching down at in those videos?Last edited by Battson; 03-12-2016, 08:50 PM.Comment
-
Yes, it works well, but we are still fine tuning it for Bearhawks. It is working better for me than the springs and chain it replaced. I'm going to tighten the chains to see if I can keep them taught in flight.
Wish I would have filmed the ones that were in use with the leaf spring, they always loosened up after a while. Probably because of stretching the clips used to attach them.Comment
-
My first thought watching that video, was I wish I knew what my leaf springs were doing to compare with. Hard to know exactly how much better it is, without having ever seen what I have today.Comment
-
Yeah, I wish I had done that, but it's fairly easy to mount one on the tail handle, that is where the GoPro was mounted for the landing videos. Maybe someone can do that so we can compare?
Between the feel from the seat, the video below, and watching video of landings at Boyd Ranch (on my Vimeo page), I have a pretty good idea. The difference in feel is significant from the pilots seat. Much smoother. So much so, except for the two off the initial LZ, I didn't realize my tail was touching down on those takeoffs, don't recall feeling it and didn't know it happened until I saw the video. Also, several were the slowest takeoffs I've ever made - 37 to 39 mph indicated, but too early to know why that occurred, so I'll have to see if it is repeatable then look into it further.
I had 30 gallons on board, and 200 lbs of me and about 30 lbs of other "stuff" so weighed about 1950 lbs or so with 31" Bush.wheels.Comment
-
So you are using the coil overs at the moment, right? I think I need to consider buying a set...
I notice the angle of the king bolt is closer to vertical with the coil overs, compared to the air shocks and leaf spring - how is that riding?Last edited by Battson; 03-13-2016, 01:22 AM.Comment
-
Yes, coil overs went on just before we left for Baja and have remained on since.
I was concerned initially with the King pin angle and went back and forth with Dan about that. He assured me it would be fine, and so far it has. As he pointed out, the angle is better at faster speeds since not as much weight is on the tail and as we slow the angle flattens, and at higher speeds is where shimmy occurs.
Every TW combination I've used has shimmied at some time. I've found low tire pressure or loose attach bolts to be consistent culprits. With low tire pressure, heavily loaded, and by bouncing the TW during landings on pavement, I've experienced mild shimmy 3 times with the T3 installed. They were the mildest events I ever had. Pumping the tire up to 25 psi, where run it with the leaf also, took care of that. So I really can't attribute the shimmy I experienced to the king pin angle or the T3.
When I preflighted the plane for the Baja trip, I noted the TW pressure appeared low due to the tire sag. I was curious if it would be an issue withe the T3, so I let it go. We are at 5000 feet altitude so tire pressure gets is even lower when we fly from here to sea level elevations. On the Baja trip, the first time it shimmied was after a week at sea level and when we were half way back. I added air when we got home, and it's been fine since.
This brings up another topic which I haven't addressed yet, but will investigate in a few months, and that is which TW might work best for off airport flying now that the T3 is installed. There may be a lighter weight TW that would have the same flotation of the Baby Bushwheel, and would weigh less. With the T3, I no longer need the shock absorption of the BBW. I'll post after I get further into that.Comment
-
So I understand the Baby Bushwheel is 12 lbs including the housing, or 10.5 lbs without.
You might consider the Tundra Tailwheel, weighing in at 8 lb, although I believe there is noticeably less floatation than the BB. It does however give more than enough cushioning compared with a BB, in some ways it's better at cushioning.
The floatation is an issue for me when I land on beaches and taxi over soft sand. It is not an issue on gravel, mud would probably be an issue though. By "issue" I mean I need to use more power, it doesn't actually get stuck like the 10" tailwheel would.
Comment
-
The more I look at those photos of the T3, the more the mechanical engineer in me thinks it needs to be redesigned with just one big coil-over in the middle.
Such an easy change from the looks of the design, provided an appropriately sized coil over is available. There would be many benefits to making a change to just one coil over (like you could probably keep the stock steering...) lighter overall I am sure, simpler, more aerodynamic, aesthetically pleasing, etc.Comment
-
I agree with you Battson. I've thought the same thing and have looked into it a little. Apparently they make stiffer springs for big, like 300lb, guys that are into MTBing so I think it realistically could be done.Originally posted by BattsonScratch Built 4-place Bearhawk. Continental IO-360, 88" C203 McCauley prop.Comment
-
I've used 3 tailwheels on the Bearhawk since it's first flight in 2009 and recorded the actual weights of each. Maybe my scale is off, but they are heavier than published specs according to my measurements:
1. Scott 3200 8-inch (8lbs)
2. Tundra Tailwheel by Iron Designs (10.5 lbs)
3. Baby Bushwheel (13 lbs)
They all worked well and have individual characteristics that make each more suitable for a particular application. Personal preference plays a role as well.This is a quick summary of my thoughts on them attached to a leaf spring. As mentioned before, my impressions of the best TW for my application may change if they are attached to the T3 since it absorbs much of the impact that the tire would otherwise see on a leaf spring.
The Standard Scott 3200 is a great wheel for 8:50 or smaller sized tires that primarily fly off of pavement of hard packed surfaces. Carry a spare tire and tube if you are traveling far from home, because they do go flat and many shops don't stock tubes and tires. Parts availability is excellent, although they typically have to be ordered.
The Tundra Tailwheel is a Bob design and Eric Newton sells the latest upgraded version of that. It fits in a very nice spot between the Std. 3200 and the BBW so is better for those with tires larger than 8:50's or on ground that hasn't been compacted. This TW also represents the best all-around general-purpose value between the 3. I sold mine to Jon because I had the other two and didn't need 2 extra tailwheels lying around. Because the other two share many of the same parts, I decided to keep the Std. Scott 3200 and let the Tundra go. Jon got it for a great price. Carry a spare tube and tire for this one as well.
The ABW Baby Bushwheel is in a class of its own. It is not needed for general or casual off airport use, but if you are serious about flying off airport and do that frequently, this is the way to go. It is a very robust design that handles differing terrain and conditions the best and will get you home without damaging the rim should it go flat while in a remote location. It has excellent flotation ability and is quite good at absorbing impacts. A great deal of thought went into it's special purpose design. It is common to run lower pressures in this tire (10 to 15 psi) while off pavement. The downsides are weight and cost. I tried an AeroClasic tire on the wheel for a while as cheaper alternative (I thought) to the BBW tire. I had a flat tire landing in Marana, AZ and by the time I got off a very busy runway, I'd ruined a $400 rim. Not Good. When that tire deflates, the rim is left to ride directly on the pavement. The BBW is wide even when deflated and provides better protection of the rim. With care, I could have flown the 650nm home without worry on that tire. As it was, I had to have a new rim and tire shipped to me. Lesson learned.
Now with the T3 installed, I'm re assessing which TW is best for my purposes. I may be able to use a lighter TW that still maintains good flotation and shed 5 lbs or more from the tail. All of the above 3 are potential contenders but a wide tire for flotation is a must so that eliminates the Std. 3200 right away. I'm also looking at others including Matco and Tundra Lite's by Jim Pekola. Jim's are either free castoring or locking. The locking option may provide the best option; free castoring most of the time, with the ability to lock when taxing in cross winds or on side slopes. With Jim's set-up I can remove the T3 steering and save another pound.
The Matco's weight for an 11-inch tall wheel is advertised at 9.6 lbs and Tundra Lites is advertised at a little over 7 lbs for an 8-inch wheel.
BTW, the actual weight of my old TW leaf spring is 5.5 lbs.
Mike
Comment
-
Originally posted by whee View Post
Talk to Dan about it. He does have a single shock version for lighter planes that is being tested by others now. The dual coil overs on mine have a 750 lb rating; they do make a 1,500 lb spring for these.Comment
-
Hi All
Mike has been fantastic with helping to get the suspension dialed in for the Bearhawk. The double shocks with coil over or air have been working out well for most applications. I have been begun testing a Light Sport version, currently on three planes. Rans, Light J3 experimental, and my full size 18 cub. All three are being tested with coil over shocks at this time. The Rans and J3 have 750 lb. rated shocks and my cub has a 1500 Lb coil over. The video below shown with my cub. Tail weight for this video was 138 lbs. static (without 195 Lb. pilot and with 18 gallons fuel). Its too early to tell if this will be suited for the higher tail weights. It may prove that having the double shock mounted close to the tailwheel itself provides better torsion control, eliminating some of the shimmy common with the narrow leaf spring. Right now testing continues for the single shock.
Comment
-
Blackrock Thanks for all of the videos and information. I left out some tubes around the rear tail post on my LSA and have been trying to decide which tail spring setup to run. The built in stinger mount (plans), only allows for that one option. I'll go ahead and build a cub style leaf spring mount. A bolt on stinger mount could be used, leaf, or Dan's setup.
Cubamigo Glad to see your working on a LSA version. I like the looks of the narrower, single shock setup for that application. The Bearhawk LSA is a very clean airframe for its type, I'd like to keep things as low drag as possible. The vertical impacts are drastically softened over the spring setup, what are your thoughts on side loads? Does the arm that runs from the pivot to the tailwheel allow for any twisting or is it rigid?Comment
-
Cubamigo Glad to see your working on a LSA version. I like the looks of the narrower, single shock setup for that application. The Bearhawk LSA is a very clean airframe for its type, I'd like to keep things as low drag as possible. The vertical impacts are drastically softened over the spring setup, what are your thoughts on side loads? Does the arm that runs from the pivot to the tailwheel allow for any twisting or is it rigid? [/QUOTE]
My thought is the side loads are no more than would you would have with the standard leaf spring setup. I believe the dampening shock relieves stresses to the fuselage frame in both directions, vertical and horizontal. The tail arm is more rigid than a leaf spring. Keeping the tail arm from twisting probably helps to prevent tailwheel shimmy.
Comment
Comment