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Flat Tire and Ground Loop - RV6

fbrewer

Well Known Member
Got to thinking about flat tires on the RV-6.

I had a right main tire blow out in the air on a Beechcraft V tail. The landing was sporty. As I slowed, the drag to the right was very strong.

Full left rudder did not stop the drift to the right. Only when I applied left brake was I able to stop the drift and keep it on the runway.

So, as I think about my new RV-6, I could imagine a flat tire could easily lead to a ground loop on landing.

Has anyone here experienced a flat tire when landing a tailwheel RV?

Were you able to keep the bird from ground looping?

I'm thinking a 3-pt landing would be better than a wheel landing in this situation.

Any thoughts?
 
I landed with a flat tire at Astoria with Mike Seager in his -7 during my transition training. Not sure when the tire lost air, but it was hard to notice until we slowed down, then it became obvious. We were able to taxi off the runway, but barely. In short, no tendency to ground loop, but perhaps that was because tire lost air only after touch down. Hard to know for sure.
 
Ground loop

Landed my 6 loaded heavy and the tire blew on landing. Pulled to the left which made men think seized brake but was easy to control. No real issue, wheel pant even survived.
 
I think I've had two flats landing RV taildraggers, and both of them were completely controllable - like someone mentioned above, it was hard to figure out there was a problem until I got slow. One tip however, if you figure out you've got a flat, don't let it stop while you're still on the runway, cause no amount of reasonable power is goign to get it goign again!

Get it clear before it stops - the other pilots will thank you.
 
Havasu

I had a flat in the air in an RV4. It became very obvious half way through the roll out and barely made it off the runway. Easy to control with the wheel pant acting as a skid. Ground off some fiberglass but that was all.
 
Members,

Thanks for the feedback. I feel better knowing that the landing is mostly controllable.

Did you wheel land or 3-pt?
 
Wheel

I wheel landed an 8 with an unknown flat right main gear and it felt odd as I started to slow. Feeling the drag to the right I used rudder then brake to keep straight. Not knowing exactly what had happened and quickly realising that taxiing wasn't going to be easy I decided to stop where I was. It ground the wheel pant down a little and sure, I closed the runway for 30 minutes but hey. The landing was controllable and nothing to worry about. Good tip: when the ground support crew put a dolley under the tire, the wheel pant didn't quite fit and suffered more damage. Remove it before allowing the dolley to be used which in itself was not easy because the lower screws were just about touching the runway and tough to remove. Took a few days to re-glass and paint the wheel pant.
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Buy yourself a motorcycle TPMS (tyre pressure monitoring system)off ebay
Screw on Valve cap sensors and a digital pressure and temperature monitor for your panel....they even have ones with an Iphone APP.

At least you can prepare for it if you know your tyres flat in flight
Joe
 
I am glad to see that it seems this is a somewhat controllable situation. I am relatively new to the RV and Tailwheel world. Purchased my -8 in December 2016. About a month back I was doing a quick fuel run and when heading home I taxied to the hold short line with no issues, did a quick run up and when I went to pull onto the rwy, the plane would not move. The only thing it would do was pivot on the flat. It has haunted me ever since what would have happened if I was able to get it off the ground before it went flat (no puncture, fairly new tube just split). I am based at a 30ft wide strip with unforgiving runoff areas. But like someone previously said, it was not going to move, so I always assumed I would have touched down and immediately pivoted right into the woods. But sounds like it is a situation that can be dealt with.

Jonathan
 
I've not landed one per se but I've had 3 flats after landing. One time I taxied back to do another lap and couldn't get the plane to move. Another time it happened in the hangar overnight. The last one was last weekend. Landed and taxied to the hangar and was able to drag the plane back in the hangar as the last air left the tire. I was lucky to be on my home field for all three.

The reason I am posting is because all three times seemed to be from low pressure in the tires. I've run them between 25 and 35 psi over my few years of ownership, while I've tried to pick a favorite. All three tubes had a small sidewall pinhole caused by wear. Twice, the last bit of tube gave up on a flight (or more likely a landing) in November just after the first real cold snap. I'm sure the tires had worn all along but the lower pressure on the first cold morning seemed to be enough too allow the tube to rub against the tire sidewall and cause the inevitable slow leak. Just food for thought.

I too am happy to hear the landings were easily controlled!
 
Tires

What are thoughts on different tires and number of ply.

A friend who raced at Reno used to run ten ply tires for two reasons. One could run real high pressure for faster roll out on race start. Two if tire pressure got low the ten ply tire could support the airplane better with less chance of tube failure.

Thoughts? Any body running 8 or 10 ply tires on their RV?
 
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I am not aware of any, and I am not sure the trade-offs would be worth it.

There are a lot of different engineering aspects of aircraft design that anyone without formal training would not be aware of.

The experimental category is great because of the freedoms it provides but very often experimenting happens in blissful ignorance (before criticizing me for the use of the word ignorance, please look up the definition).

Tires are an important part of the landing gear system. They provide a lot of energy absorption (when needed). Take note of the amount of tire deflection in the slomo portions of THIS VIDEO as an example.

If you use stiffer tires (because of higher pressures or more plys), they are absorbing less energy. That means more energy gets transmitted into the gear leg and possible the aircraft structure itself.

A disheartening example is an RV-10 project that recently dropped 4 feet to the hangar floor when a lift failed. The main wheels were restrained by the lift and unable to flex when it hit the floor, so in this case the tires were the only thing available for energy absorption. The abrupt stop on the hangar floor resulted in major damage to the fuselage.
http://www.vansairforce.com/community/showpost.php?p=1213639&postcount=1

I would recommend not experimenting with higher ply rating tires. They will be heavier, cost more, and in the end could possible cause you problems that you may never have imagined.
 
Scott, what is the recommended tire pressure for the various models? Been doing a search getting mixed answers.
 
Scott, what is the recommended tire pressure for the various models? Been doing a search getting mixed answers.

There is no published recommendation except for the RV-12. It (in most instances) gets built matching a standard... the certified S-LSA.

For all of the others, there is not standard (some people operate at 100 over recommended gross, etc.).
 
Any idea what causes a sidewall pinhole? I had one a few weeks ago. It troubles me when I can?t determine a cause.

It is usually attributed to rub abrasion between the tube and the interior of the tire (if you inspect the interior of a tire closely, it is quite rough and abrasive).

The typical cause is lack of lubrication (not enough talc), and/or to low of a tire pressure which causes excessive side wall flex (and a lot more movement of the tube within the tire).

When I install new tires/tubes, I heavily coat the interior of the tire and I lightly inflate the tube and rub talc over its entire exterior before inserting it in the tire.
 
Any idea what causes a sidewall pinhole? I had one a few weeks ago. It troubles me when I can?t determine a cause.

I think it's just normal wear. The tube is independent of the tire so there is inevitable movement between the two. I think this can be exacerbated by having lower inflation pressures. That's only an opinion though. At some point the tube is going to wear through regardless. As far as talc goes, I think there is only so much you can do. If you've ever changed a tube and used talc, once the surface is covered, the rest of the talc just sits in a pile at the bottom of the tire, presumably going to waste. So really no sense adding a cup full.
 
I think it's just normal wear. The tube is independent of the tire so there is inevitable movement between the two. I think this can be exacerbated by having lower inflation pressures. That's only an opinion though. At some point the tube is going to wear through regardless. As far as talc goes, I think there is only so much you can do. If you've ever changed a tube and used talc, once the surface is covered, the rest of the talc just sits in a pile at the bottom of the tire, presumably going to waste. So really no sense adding a cup full.

Like anything with airplanes, we can talk about what to do, but that doesn't mean someone will no how to or will do it correctly.

I have seen the aftermath of numerous tires where not enough talc was used.
It seems logical to me that someone wouldn't assemble the wheel with a pile of talc in the bottom of the tire so I didn't bother mentioning it, but short of it piling up, there is strong evidence that it is beneficial to have it coated heavily.
I actually do dump enough in so that I sometimes have to shake out some excess when finished. This allows tipping the tire on its side and shake it around to coat the sidewall of the tire real well (the most important are to have talc).
 
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Like anything with airplanes, we can talk about what to do, but that doesn't mean someone will no how to or will do it correctly.

I have seen the aftermath of numerous tires where not enough talc was used.
It seems logical to me that someone wouldn't assemble the wheel with a pile of talc in the bottom of the tire so I didn't bother mentioning it, but short of it piling up, there is strong evidence that it is beneficial to have it coated heavily.
I actually do dump enough in so that I sometimes have to shake out some excess when finished. This allows tipping the tire on its side and shake it around to coat the sidewall of the tire real well (the most important are to have talc).

I coat with talc too. I expected to find something sharp inside the tire. It went flat right after spinning around while holding one brake. Afterward I considered what the tire experienced in sidewall flex. I don?t do that anymore.
 
I coat with talc too. I expected to find something sharp inside the tire. It went flat right after spinning around while holding one brake. Afterward I considered what the tire experienced in sidewall flex. I don?t do that anymore.

That's a good point too. And good practice to try to keep the tires rolling when you can. Anything that distorts the tire/tube is going to cause more wear than less I would think. I don't remember reading somewhere whether you had just changed your tube when it went flat, but if not, I stick to the opinion that your experience is normal.
 
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