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Thread: 180 tailwheel

  1. #1
    wingnut18's Avatar
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    180 tailwheel

    baby bushwheel vs. 14" xp?
    Last edited by wingnut18; 02-09-2011 at 09:37 PM. Reason: x

  2. #2
    StewartB
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    I use a 14" XP on my Cessna. I had one bad summer of getting stuck and blowing tailwheels. I'm not talking about leaving a rut, I mean stuck. Take a 3200# Cessna and stick it tight in the ooze with no help in sight and a long walk to firmer ground and your day just turned to crap. Do it five or six times and you buy a tailwheel. The 14" XP solved my problems. At that time the Baby Bushwheel 3400 version wasn't available. With the 500# static load limit on the Baby Bushwheel I doubt I'd have gone that way anyway. When I weighed my 180 the tail weighed 200# in three-point empty. Add 1400# useful and it's easy to imagine the tail weight being 1000#. Did I mention how much fun being stuck with a blown tailwheel is?

    My standard answer when asked is that I prefer the smallest tailwheel I can use that doesn't get stuck. If all I had was a blown tire problem, I'd have foamed the tire. Getting stuck with an inflated tire required a bigger, wider tailwheel. The blow-out thing required a tougher tailwheel. The 14" XP fills the bill.

    Bad things? Your AOA will be decreased. The stress on your tail spring will be higher. If you land on pavement you'll likely experience occasional shimmy. Ground handling is slightly degraded on improved surfaces.

    Good things? No more flats. No more getting stuck. My prop is much happier when taxiing on soft ground. You get more exercise climbing up into the plane.

    Other necessary equipment? Big mains. I use 29" Bushwheels, and wouldn't be happy with the AOA using anything less.



    Stewart

  3. #3

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    I love the Baby Bushwheel on my '53 C180. it has enough load capacity to handle me and the noise (rattling and clanging) in the rear fuselage has gone completely away.
    My .02 for the B Bushwheel. And of ccourse the mains also. Highly addictive.

  4. #4

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    Quote Originally Posted by vet114
    My .02 for the B Bushwheel. And of ccourse the mains also. Highly addictive.
    I hear that there's a twelve step program for this malady.

  5. #5
    wingnut18's Avatar
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    does the 12 step progam involve buying a Maule?

  6. #6

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    Oh, heavens no! Find your support group wherever you're the most comfortable. Serious conditions like this require like minded folks, and bushwheel addiction (a very serious and expensive condition known to break up entire familys) crosses many socio-economic boundarys and airplane types.

    Still hoping to join this co-dependent group someday.


  7. #7
    hottshot's Avatar
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    We have come to see that the 12 step program is not near enuff there have been far to many relapses... so you better double your steps.



  8. #8

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    A twenty-four step program!? YEEEEEESH, you're not making this any easier, Wup.

    Looks like I'm responsible for mission creep again, my apologies to those who are looking for real answers.

  9. #9
    Crash's Avatar
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    The "baby" Bushwheel tail wheel is a tough little tire. I wouldn't hesitate putting one on a Cessna 180, especilly an early light C-180 ('53 to '59). They are a lot softer and wider then an XP tail wheel. I think in soft sand and mud it would work better then the XP. I am thinking about going this route on my C-180. Crash

  10. #10
    wingnut18's Avatar
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    Crash,
    I have nothing but the highest regard for Bushwheel products, I have 31"s and a Babybush on the Cub, and have a set of 29"s for the 180, would you still run the Babybush on a '79 with 3190lb. gross?

  11. #11
    Crash's Avatar
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    Quote Originally Posted by wingnut18
    Crash,
    I have nothing but the highest regard for Bushwheel products, I have 31"s and a Babybush on the Cub, and have a set of 29"s for the 180, would you still run the Babybush on a '79 with 3190lb. gross?
    I don't think the FAA would have approved it if it wasn't tough enough. Worse thing that will happen is you'll blow it. Shouldn't be that big of an accident if you do. Take care. Crash

  12. #12
    StewartB
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    I wouldn't think Alaska Tire and Rubber would have molded the words "500 pounds maximum static load" into the tire if they really meant 1000#.

    What other parts do you intentionally exceed the design limits of?

    If the Baby Bushwheel could handle the load of my 180, I'd buy one simply because it's not as tall. The AOA would be better and the stress on the tailspring would be less. I didn't define the weight limits. Alaska Bushwheel did.

    If max weight capacity didn't matter I'd have 31" mains, but 3000# max gross is all you get with 31s. 3600# with 29s. My gross weight is 3190# and I use it regularly. I did the math. Same deal.

    Stewart

  13. #13

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    SB,

    Do you really think you're putting that much load on the tail with the 1400# useful load? I'd venture to say that if you did the calculations you'd find the tail weight is much less than you think it is, otherwise the tailwheel would be putting a groove in the asphalt on a hot day.

  14. #14

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    Quote Originally Posted by Strata Rocketeer
    SB,

    Do you really think you're putting that much load on the tail with the 1400# useful load? I'd venture to say that if you did the calculations you'd find the tail weight is much less than you think it is, otherwise the tailwheel would be putting a groove in the asphalt on a hot day.
    Yeah, I gotta agree, 1000lb on the tail just isn't realistic. If you start with 200 lb empty that means that 1400 lb will add 800 lb. That's more than half the additional weight. In order for a 1400 lb load to put 800 lb on the tailwheel, the center of mass of the load would have to be further aft than the halfway point between the mains and the tailwheel. From the main axle to the tailwheel axle is about 20 ft (244 inches). From the main wheels to the aft baggage compartment is about 100 inches. That means that if all of your 1400 pounds was loaded in the aft baggage compartment, it would only add 583 lb to your tailwheel load, bringing it to 783 total.

    Is it possible that 1400 lb will add 300 to your tailwheel? maybe, deepends how far aft you load it. 800 lb? never anywhere close.

    Note, I used loading arms for a 185D, I assume that your big tail 180 has similar dimensions inside.

  15. #15
    StewartB
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    Do I think it's that heavy? Yes I do. CG calculations are for in-flight loads, not 3-point. Although I have a tripod the width of the fuselage is relatively small compared to the length, so for static loads I'm dealing more with a balanced bipod. Of my 1400# useful load virtually all of it is loaded beind the mains while in 3-point. I've often wondered exactly what the static tail weight is at gross. It shouldn't be hard to check.

    If my tail weight does only come out to 700#....that's still more than 500. Is it reasonable to assume the tail weight at gross is at or below 500#? It sure doesn't seem likely, does it?

    Stewart

  16. #16
    hottshot's Avatar
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    Quote Originally Posted by Crash

    I don't think the FAA would have approved it if it wasn't tough enough.

    Good Point, There are alot of Heavy 185's out there with the 1154.R on. Worry not!! The little monster is built with 100% Kevelar, and those of you that were at Johnson Creek last year got to see the demo we like to do with the Razor Knife to show just how tuff the Baby bush wheel is.


    Like they used to say.... Try it you'll like it.

  17. #17
    StewartB
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    Wup,

    Why the 500# limit then? You say it's tough enough, but the tire says 500#. As the responsible pilot I'm required to operate within the limitations of my airplane. 500# maximum static load is very specific.

    Stewart

  18. #18
    hottshot's Avatar
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    The calculations were done on a late model 185 at Full gross Aft CG and you should not exceed the 500# Static load. I will look up the exact data and post it later.

  19. #19
    StewartB
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    Cool, I'll get some sandbags and a scale and load my plane to max gross. We can compare numbers.

    As a side note, when I was marking my sight gauges in the 12 I added 5 gallons at a time and lifted the tail from 3 point to flight attitude and set it on a stand. If you think 10 gallons of gas in the tanks (which is as forward as any useful load can be carried) doesn't add to the tail weight, I'm here to testify that you're mistaken. The added tail weight is more dramatic at 3-point than I would have believed. Holding the tail at flying attitude it wasn't even noticable.

    Stewart

  20. #20
    hottshot's Avatar
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    You are right about the Tail weight being "more dramatic at 3-point than I would have believed" But between the Maule and the 185 the Tail weights were Very close I think some where in the 480# range but I will have to check for sure.

  21. #21

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    Quote Originally Posted by StewartB
    Do I think it's that heavy? Yes I do. CG calculations are for in-flight loads, not 3-point.
    Doesn't matter, I did the calculations for 3 point attitude, relative to the wheels, besides, the difference beteeen level flight and 3 point attitude is miniscule. a 12 degree nose-up attitude doesn't shift the weight enough to make any significant difference. weight is weight and moment arms are moment arms. the CG doesn't magically move because the airplane is on the ground.

    Quote Originally Posted by StewartB
    Of my 1400# useful load virtually all of it is loaded beind the mains while in 3-point.
    Well, obviously; all of the cabin is behind the mains, so the load would *have* to be behind the mains. Regardless, what I said earlier is true, in order for 1400 lb to add 800 lb of load to the tailwheel, it would be necessary to load the entire 1400 lb *more* than 10 ft aft of the mains. It's simple math, weight and arms, no magic and nothing changes much because you're on the ground. The aft baggage compartment in a 185 (and I'm assuming a late model 180 is similar) is a little over 8 ft aft of the mains, so unless you have an extended baggage and the entire 1400 lb is lead ingots loaded in the extended baggage, you won't ever add 800 lb to the tailwheel load.



    Quote Originally Posted by StewartB
    If my tail weight does only come out to 700#....that's still more than 500.
    The 783 lb on the tailwheel was *if* you loaded the entire 1400 lb in the aft baggage compartment. I'm assuming you don't load 1400 lb in the aft baggage compartment. The load on the tailwheel won't be anything close to 700 lb.


    Quote Originally Posted by StewartB
    Is it reasonable to assume the tail weight at gross is at or below 500#? It sure doesn't seem likely, does it?
    Sure, it would be possible to exceed 500 lb. I already agreed with you on that point in my previous post. My point was that 1000 lb, or even 700 lb is not within the realm of physical possibility.

  22. #22
    StewartB
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    I'm done hypothesizing. I'm going to find out. I've got a few calls out looking for the scale. I figure I'll put 200# of fuel in the plane and borrow 20 sand bags for my little test, which I'm definitely intending to do. I'll let y'all know what I find. I'll start with the pilot seat, both front seats, add passengers, and finish with the balance in baggage until I'm at full gross and within CG.

    I'm pretty sure what I'll find, but then I've unloaded my plane a few times to facilitate lifting the tail to change the tire. If I'm wrong, I'll fess up to that, too. Hypothesize, experiment, validate. I think that's called science. Everything else is just talk.

    While I'm at it, I'll add 711# to my 12 as well. We'll see what my 60# (empty) tailwheel weight does at gross.

    Stewart

  23. #23

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    Quote Originally Posted by StewartB
    I'm done hypothesizing. I'm going to find out. I've got a few calls out looking for the scale. I figure I'll put 200# of fuel in the plane and borrow 20 sand bags for my little test, which I'm definitely intending to do. I'll let y'all know what I find. I'll start with the pilot seat, both front seats, add passengers, and finish with the balance in baggage until I'm at full gross and within CG.

    I'm pretty sure what I'll find, but then I've unloaded my plane a few times to facilitate lifting the tail to change the tire. If I'm wrong, I'll fess up to that, too. Hypothesize, experiment, validate. I think that's called science. Everything else is just talk.

    Stewart
    Agree, nothing like empirical data. Let me know what you find out

  24. #24
    wingnut18's Avatar
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    boy did I let something out of the bag!!

  25. #25
    hottshot's Avatar
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    Quote Originally Posted by wingnut18
    boy did I let something out of the bag!!





    LOL

  26. #26
    StewartB
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    With the help of a professional airplane weight and balance mechanic and 20 sand bags, I did my test to see what the actual tail weight is at gross weight in three-point attitude. I had previously overestimated the total weight, but he weight still exceeds that allowed by the Baby Buswheel.

    The test plane is a 1975 180J with a few tricks added. I had a weight and balance done a couple of years ago and as it sits with all these tricks it weighs 1876#. In level flight attitude the tail weight is 130#. In three point it's 200#. So, I experience a 53% increase in the three point with no other changes. My gross weight is 3190#. Today I had the plane on certified scales and loaded it with sand bags in a well-distributed load that took it to 3190# and was within legal CG. The tail weighed right at 600#. I could have played with the loading and changed it a bit up and down, but this is a representative weight while in a normal (legal) load distribution. Without question a 3500# 185 would have 700# plus in a similar test.

    For estimating purposes I can divide my plane's total gross weight into five parts. Each main carries approximately 2/5 of the weight while the tail carries 1/5. This is not perfect by any means, but it works on my plane.

    I wanted to know, so I paid my money and found out. No speculation, no smoke and mirrors, no BS. There it is.

    Stewart

  27. #27
    wingnut18's Avatar
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    thanks alot Stewart, very helpful,

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    Thanks for the info Stewart.
    Jack

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    Stewart,

    Thanks for going out and actually measuring. I'm curious, what's your airplane's empty cg? Also, if you remember, what was the cg in your test load configuration.

  30. #30
    T.J.'s Avatar
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    delete

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    Quote Originally Posted by T.J.
    So, can we assume from this test, that the difference in weight between 3 point and level is not "miniscule"?
    Can I do my weight and balance calculations from the 3 point attitude now?
    OK, I might have overstated that a little

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  33. #33
    Bill Rusk's Avatar
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    Thanks Stewart.

    Nice to get facts rather than opinion.

    Thanks for doing that.

    Bill

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    Stewart, I really appreciate your effort in getting real facts. I recognize that this was real work. I enjoy my C180 in addition to my PA-12. This is great information. Hard facts like this make this a great site.

  35. #35
    StewartB
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    You're welcome.

    While we all know pilots that cringe at the thought of weighing their planes because they know they'll lose useful load, I'm a fan of accurate data. When my 180 was stock and had a max gross of 2800#, I recognized I had physical space and available performance to carry more than that. I saw a value in adding Kenmore's 3190# gross weight STC to utilize the capabilities while not exceeding defined and stated limitations. To have made the effort to increase my legal load makes compromising that gain unacceptable. On the flip side, it appears that the Baby Bushwheel is perfectly appropriate for older, lighter grossing 180s. The applicability for standard 2800# 180s is harder to anticipate. Those owners will need to decide for themselves.

    Aalexander, my empty CG is +36.3. The gross weight/600# tailwheel load configuration was at +46.3 (my aft CG limit is 47). I have a nose heavy airplane. I don't mind because I never fly without gear that I use for balance. I had about 180# of fuel on board for yesterday's test. It would have been fun to fill the tanks and see what effect it had. If I'd had more time I could have loaded in two or three configurations and graphed the changes but such a graph would only be applicable to my plane and I had already found out what I needed to know.

    I had flown to Birchwood with three relatively soft tires. We were forced to increase the pressure in the 29" mains to keep the plane centered on the scales. While my tailwheel had looked normally inflated on arrival when the plane was essentially empty, by the time we had it to gross the tailwheel was very nearly resting on the wheel with the tire squished flat. I increased the pressure to the point that I had a normal 1/2 to 1" flat contact patch on the tailwheel. Before flying home I deflated the mains back to 10# but left the tailwheel alone. Upon taxiing out the same way I had arrived, the noise and roughness transmitted by the hard tailwheel on my now empty tail was alarming. It made me wonder how the Baby Bushwheel would perform given the same circumstances. Another test might be in order. Enquiring minds want to know.

    Stewart

  36. #36

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    I will eagerly await the results of further testing. There is no substitute for hard facts.

  37. #37
    hottshot's Avatar
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    Just the facts man.


    http://sparky.supercub.org/photopost..._data_info.pdf


    ps ALL of our tires are UNDERRATED load wise

  38. #38
    StewartB
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    Wup,

    My interest in this topic is centered on my airplane and my responsibility as a pilot to operate the airplane within it's limitations. I didn't pick the 500# max static load limit, ATR did. Even if your formula is flawed, ATR is protected by the 500# limit that's emblazened on your tire.

    It's my nature to question statements of fact that don't add up. That's exactly what I did here. No calculations, just a certified scale. To eliminate errors, the weigher insisted we not just weigh the tail as I had planned. Instead, we weighed all three gear positions. Having done so, I'd submit that your formula is incorrect. The tail weight you're reporting would be found at a gross weight of approximately 2850 to 2900# using my plane. I would suggest that the subject is in question enough to warrant validation of your data. It seems the timing may be perfect, since there's a display show this weekend. Personally I have nothing to gain here. I did the test and found a weight condition that was significantly less than my original estimates. Oddly, it's significantly greater than your estimates. I'd hope a manufacturer of an STC'd product would be motivated to find the truth.

    You can borrow my plane if you'd like to test your formula.

    Stewart

  39. #39
    hottshot's Avatar
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    I am just showing you how the test was done and certified by the FAA



    and that's the Truth

  40. #40
    StewartB
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    Fair enough. I was just trying to find out how much it really weighed.

    Stewart

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