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26" tire choice

bob turner said:
Gordon - so spin-up inertia doesn't affect initial adverse drag on touchdown?

Are you routinely practicing in 20 kt direct crosswinds?

Granted - the hard 26s do handle crosswinds almost as well as an 8:50, but have you tried 29s in a 20 knot direct xwind?
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Well Bob, you do know how to get me started, don't you? :lol:

So - re "routine" 20 kt crosswinds, no. Routine turbulent teens crosswinds, yep. Teens gusting 20s crosswinds, sometimes. Occasional (rare) 30's cross, yep. Wind more or less down the rwy? Rare! My understanding is that when KTDO was built during WW2, it was deliberately oriented for military crosswind practice.

Re the tires - I switch around between 26 bushwheels, 31 bushwheels, and 8.50s. Never 29s. I haven't noticed a difference in crosswind handling between those tires. But never really looked for a difference either.

Re spinup, sure it's there, but to my senses it's negligible - I simply don't feel it. For fun, go do some one-wheel landings with no crosswind, then with the new tires do it again and see what it feels like to you. Granted, the J3 is lighter than the -12, so any difference between tires would be a little more pronounced in the J3.

If I get ambitious, maybe I'll do some comparative calcs and email 'em to you. Just for grins and giggles. I'd need your operating weight and CG as measured from the axles.
 
Gordon has me beat - at 20 knots I am maxed out. No more rudder, no more aileron, and once scraped a wing. Easy fix; a quarter-inch fabric patch.

I seek them - but only where I can walk home. We will have 26, on an otherwise stock J3 - and just in time for winter crosswind practice.

Should I tell you about my very experienced friend with thousands of Cub landings, and 31s? Nah . . .
 
When it comes to scuffin your tires before you landed on asphalt: the old rock hard 36" Goodyear Airwheels were the worst tire
I ever flew on a Cub, at 61/62 lbs respectfully , wheel landings were "spooky"
Without scuffin em first to get all that weight & moment turning! Once you had em spooled up they were ok. Those tires were extremely stiff, and very hard on the Airframe, and they really gave the bungees a workout! With 6 screws on each wheel! I still cut off some valve stems! Once at King Salmon in front of a Mark Air 737 flight that had to circle, because I freaked out because the arestor cable was 'up for the fighters, and I wasnt sure if I could roll over it or not? Georgie Tibbets to the rescue! We got her off the runway, found a tube at Penn Air
And got going again. In big crosswinds I like to exceed diagonal: and land straight across into a taxiway..........[emoji6]

Sent from my moto e5 go using SuperCub.Org mobile app
 
bob turner said:
Gordon - so spin-up inertia doesn't affect initial adverse drag on touchdown?
Click to expand...

Gordon Misch said:
Well Bob, you do know how to get me started, don't you? :lol:

Re spinup, sure it's there, but to my senses it's negligible - I simply don't feel it.

If I get ambitious, maybe I'll do some comparative calcs and email 'em to you. Just for grins and giggles. I'd need your operating weight and CG as measured from the axles.
Click to expand...
You two have my attention.
It seems to me the tires with the larger diameter would have less spin up resistance due to the larger radius providing more leverage. This assuming equal air pressures on each. IF the tires are being run with low pressure due to their being used in the "rough", then I would expect more spin up resistance. Enough more to cause an accident if landing on pavement.

Long ago there was a 180/185 accident at ANC when it landed on the hard with some Schneider racing slicks. They were set to a low pressure for bush landings, then when landed on the pavement they stuck like glue with the same result as landing an amphib in the water with the gear down.

Why would you land in a 20 knot crosswind with a Cub when you can easily turn and land cross runway? It wouldn't require a very wide runway in those winds. Granted, if you're using a one track road you won't have that option.
 
Why would you land in a 20 knot crosswind with a Cub when you can easily turn and land cross runway? It wouldn't require a very wide runway in those winds. Granted, if you're using a one track road you won't have that option.
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Narrow. Lined by tall trees. Vicious turbulence. Add a slick or loose surface for even more excitement. The same problems await you when taking off. We can make several attempts to land. We usually only get one go at departure. Judgement of conditions from the air looking down is different than from the ground looking up.
 
stewartb said:
Narrow. Lined by tall trees. Vicious turbulence. Add a slick or loose surface for even more excitement. The same problems await you when taking off. We can make several attempts to land. We usually only get one go at departure. Judgement of conditions from the air looking down is different than from the ground looking up.
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And what airport in the Anchorage area is this?
 
Are we limited to airports? Fly around the valley a bit and look at 90% of the private strips. At Wolf Lake the prevailing wind is 45* from the primary and crosswind runways. And I've observed some seriously sporty landings lately. And a few seriously sporty go-arounds that evolved into go-aways. Heck, fly in and out of the old Creek strip for a few years. That one's a real charmer when the wind's blowing 40 down the Yentna.
 
Just yankin your chain. The original comment was about crosswinds and paved runways though so off-airport isn't quite what the group was talking about.

I get your point though but I've never had an issue once below the treetops with crosswinds. It can be a little blustery but once you drop below the wind break it's a non-event at least when you're talking about narrow runways lined by trees.

To be honest though I just don't go up when it's that windy. What's the point of flying if it's not going to be fun and my ground speed has a good chance of being close to zero?
 
It seems to me the tires with the larger diameter would have less spin up resistance due to the larger radius providing more leverage.
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Pete, the more leverage part is correct, and of course is directly proportional to the tire diameter. However the resistance to spin up, "moment of inertia", which is the rotational equivalent of mass, is approximately proportional to the square of the diameter. That makes the spin up effort ("rotational impulse") roughly proportional to the tire diameter. I say "approximately" and "roughly" because of a tire's weird shape and mass distribution as compared to a uniform, solid disc.
 
Then there is also the temporary tire shape distortion and often out of balance natural of large soft tires hitting the pavement.
We have videoed the tires a few times on landings and it is amazing how they flex all over when they are in a low pressure state.
 
Remember, the original question was big tires for 99.9% pavement operations (at large tower-controlled airports).

Going out and seeking crosswinds is one of my great joys. It is risky, but for me, fun. Going out and landing on places that are way far away from civilization and rough enough to require big tires is way beyond my sense of fun. That is risky beyond fun for me. So is skydiving and bungee jumping.

My point - we each get to choose what entertains us. For my buddy, who has landed a stock Super Cub on a 400’ strip with 30 foot obstacles at each end on stock tires, the big tires are simply a fashion statement, and he does not care about the cost in $ and performance.
 
If he doesnt care about cost, buy a set of 29 inch Airstreaks. If you’re gonna make a statement, go big.

MTV
 
He isn’t reading this. Already ordered the 26” set above -and waiting for mag wheels, ‘cause they are lighter. My next update will be when the winter winds get here - if they ever do. Lousy year for wind at MYF so far.
 
bob turner said:
And Hot: this is not Alaska. There are no places in SoCal to legally practice big props and long rocks. All of the giant-wheeled Cubs here are for “appearance” only.
And on pavement, the larger tires (29 and 31) cut the crosswind capability to about half. They don’t dare join me on our 20 kt crosswind days (neither do the Cherokees - I have the 11th busiest airport to myself).
Click to expand...

I dunno about true, hardcore "off airport",
but there's a thread on BCP about grass or dirt strips near San Diego.
It's just starting on the 3rd page of discussion over the last 3-1/2 years, so there are some nearby options.

https://backcountrypilot.org/forum/san-diego-area-grass-dirt-strips-20457
 
I missed that last post. I have landed on all those strips and a few more - in the 70s when you could almost get away with it I landed on a couple farm fields. There is one not mentioned way up in the mountains - the Super Cubs needed a minimum of 26" tires. The amphib and my Decathlon did fine with 5" and 6" wheels.

Back to the topic - I am about to install the Grove kit. I guess the best way is to simply weigh everything while it is off the airplane, which I am prepared to do - but i heard yesterday that the Carbon Cub gains 45 lbs going from standard to 26" Goodyears. Can it be that much? I grant you the mounted Goodyears take some effort to get them on the workbench . . .

These things will make the J3 a single place airplane, even for pattern work.
 
bob turner said:
Back to the topic - I am about to install the Grove kit. I guess the best way is to simply weigh everything while it is off the airplane, which I am prepared to do - but i heard yesterday that the Carbon Cub gains 45 lbs going from standard to 26" Goodyears. Can it be that much? I grant you the mounted Goodyears take some effort to get them on the workbench . . .

These things will make the J3 a single place airplane, even for pattern work.
Click to expand...

Goodyear lists the 26 inch blimp tires at "approximately" 23 pounds each. My guess is, Cub Crafters can't do weight and balance.....in fact, I have some experience in that regard.
MTV
 
Having just taken my 29" "ultralight" Airstreaks off my 780 pound S-7S, I weighed one, 22 lbs 6 ozs. These are the ones they made for the European market I understand, not the standard streaks, and I think I bought the last pair before they discontinued them, and I'm still not too sure how I feel about that! I dropped 11 pounds over the stock 29" streaks and I love that, and I have landed lots of sharps rocks with them since (the very first flight as it so happened) and so far so good, I do have them bedlinered. I guess I'm saying I would have appreciated a comment from Airframes before I bought that they were in fact due to be discontinued, but no biggie, and I did drop 11 lbs.!

BTW, with my 106 hp plane, I noticed when I went from 8:50's to 26's, about 5 mph, but when I went from 26 to 29, couldn't tell any difference, so yeah, go big.

I got the weight wrong, and just changed it, the above is correct now, they are even lighter then I thought. A substantial savings over the standard Airstreak.
 

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I have a par of the 26" Ultralights ABW on my EX11....have not flown them yet, but they are light for sure. I too was surprised to see them discontinued....maybe folks "overused" them thinking they were the same Thickness/durability as Airstreaks.
 
I agree with bob on those strips..., ya don't need big tires for any of them except the one in the canyon that I won't mention. Around San Diego, you just have to go find spots on your own..., plenty of places in the desert that require big tires!
 
Dan Gervae said:
I have a par of the 26" Ultralights ABW on my EX11....have not flown them yet, but they are light for sure. I too was surprised to see them discontinued....maybe folks "overused" them thinking they were the same Thickness/durability as Airstreaks.
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Question is, how much of the weight savings is due to a lighter sidewall v. a thinner tread? I notice mine look "different" on the sidewalls when I roll it out of the hangar, then my regular 'streaks, almost like they constructed them a bit different. Whatever, they are working fine.....though I did finally get around to putting together a comprehensive tire patch kit along with a good small compressor, just in case. With the regular 'streaks, I think I could almost take off with zero air pressure, though I never tried it. But I did notice when pulling the valve stem prior to dismounting them/mounting my skis, they stayed mostly round enough to roll with enough power. this year, my first ski transition since getting the ultralights, I did the same, pulled the valve stems and waited to see what would happen. They got FLAT, no way to launch, so for sure a weaker side wall, which is to be expected, and makes me believe that's where the majority of the weight saving takes place. Since I routinely use Herculiner bedliner, and have for years, I'll wear it off instead of the tire "tread".

I will once again say, that I hope they never come out with a 31" Airstreak, because if they do I'll be first in line to buy a pair, darn it.
 
bob turner said:
I missed that last post. I have landed on all those strips and a few more - in the 70s when you could almost get away with it I landed on a couple farm fields. There is one not mentioned way up in the mountains - the Super Cubs needed a minimum of 26" tires. The amphib and my Decathlon did fine with 5" and 6" wheels.
Back to the topic - I am about to install the Grove kit. I guess the best way is to simply weigh everything while it is off the airplane, which I am prepared to do - but i heard yesterday that the Carbon Cub gains 45 lbs going from standard to 26" Goodyears. Can it be that much? ....
Click to expand...

I guess I don't understand why a supercub would need minimum 26" tires when an amphib or Decathalon only needs 5" or 6" wheels.
You must be talking about landing in different places.

My info sez 850 Airtracs weigh in at about 16# each, & 26" GY's are about 23#.
Dunno what an 800x4 set-up weighs, but I think a standard 600x6 tire is generally around 10 pounds.
I'm thinking that 26" airstreaks would be a lot better fit for a J3 than 26" GY's--
less weight & more flexible.
IMHO 26" GY's are more suited to a heavier airplane like a 180.
 
hotrod180 said:
My info sez 850 Airtracs weigh in at about 16# each, & 26" GY's are about 23#.
Dunno what an 800x4 set-up weighs, but I think a standard 600x6 tire is generally around 10 pounds.
I'm thinking that 26" airstreaks would be a lot better fit for a J3 than 26" GY's--
less weight & more flexible.
IMHO 26" GY's are more suited to a heavier airplane like a 180.
Click to expand...

That's all pretty much correct. 26" Airstreaks are actually a fair little bit bigger than 26GY's and from a flexibility standpoint the Airstreaks are quite a bit less firm so they can soak up more of a beating without transmitting it to the fuselage.

As far as weight, the 26" Airstreaks clock in around 21lbs each, 26GY's are 26lbs (tire and tube-an 850x6 tube is 3-5lbs), and 29" Airtreaks are 27lbs. On the J3 I'd go 26" Airstreaks all day IF I wasn't landing on pavement all the time and 29's were out of the question.
 
The best line I've heard is "when the expander tube brakes are at their best, it's just your imagination".
 
At one point, several years back, I was flying with a buddy who at the time, also had a BC-12D T Cart. For whatever reason, my right brake was strong, and my left almost non-existent. His on the other hand, was the opposite, but between our two planes, we had a good set of brakes! Both of us "came up" through flying NO brake early ultralights, and to us having brakes of any sort was cheating. To this day, when I see guys using heavy braking to make a short landing, I have to keep my lips zipped. I've had short landing contests with others who didn't land slower, but braked harder.....lips zipped. Having said that, I'd have dual puck brakes on the S-7, but winter time mounting of the Datum skis precludes that, at least the way I have mine set up. I don't feel the need myself, right now any place I can get in, I can get out, stronger brakes would change that equation.
 
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