A-10C II flight model: landing and take-off sides

[Mercury_1965]

I noticed that from DCS version 2.7 the Flight model from the A-10C_II looks like
have undergone modifications limited to:
1) landing noise (landing gear touch);
2) sturdiness of landing gear and tires;
3) sturdiness of the tires on take-off.

Basically I know that even under extreme loadout conditions + 30% over the max,
the DCS plane happily lands even at V speeds above 2000ft / min without reporting
damage. Same thing in take-off .... at speeds above 160Kts they no longer explode
tires.

In summary, the model has been facilitated.
I am not happy with this.

Edited May 26, 2021 by Mercury_1965

[Eugel]

I recently popped a tire at about 140 knots on takeoff (didn´t check the exact speed, but it was definitely below 160)

[Hammer1-1]

Im curious. Why would tires explode past 165kts on takeoff? That sounds a bit unsafe, considering the aircrafts rotate speeds will vary greatly depending on loadout and local weather conditions.

[Leg2ion]

6 hours ago, Mercury_1965 said:

Basically I know that even under extreme loadout conditions + 30% over the max, the DCS plane happily lands even at V speeds above 2000ft / min without reporting damage.

 

Mine doesn't! Can manage to break the undercarriage on most landings and conditions!

[dporter22]

6 hours ago, Hammer1-1 said:

Im curious. Why would tires explode past 165kts on takeoff? That sounds a bit unsafe, considering the aircrafts rotate speeds will vary greatly depending on loadout and local weather conditions.

Just like car tires, aircraft tires are rated up to a certain speed.  Above that speed the mateirals and construction are vulnerable to failure.

[Hammer1-1]

Car tires arent designed with the tolerances aircraft tires have. Z rated tires can go all the way past 200mph and then some safely. Aircraft tires are more durable than that. Tire rating is more for heat than anything. And before you say otherwise, I didnt say anything about weight, but for the most part its speed = heat, and heat is generated by torque to the tires or braking. Theres no torque being generated to the tires except the nosewheel, and that itself is minuscule.

Edited May 27, 2021 by Hammer1-1

[g5flyer]

On 5/26/2021 at 7:06 PM, Hammer1-1 said:

Car tires arent designed with the tolerances aircraft tires have. Z rated tires can go all the way past 200mph and then some safely. Aircraft tires are more durable than that. Tire rating is more for heat than anything. And before you say otherwise, I didnt say anything about weight, but for the most part its speed = heat, and heat is generated by torque to the tires or braking. Theres no torque being generated to the tires except the nosewheel, and that itself is minuscule.

 

I know this is old, but since you asked earlier, I figured I would give you a little insight if you are really interested. As you have stated earlier, there are a lot of speeds involved in regard to operating aircraft. One of those speeds is the tire limiting speed. These speed is in knots based on it's MPH tire placard speed. Some aircraft, like the DC10s I flew, will also have a tire speed limiting weight(TSLW). Many factors can put you up against that speed, especially in heavies. Lighter jets can hit tire limit speeds when landing with partial/no slats and flaps or flight control issues. The DC10s I flew had a tire limit speed of 204. One of the interesting things about DC10 and other MD jets is the variable flap system. By design, aircraft performance calculations took advantage of longer runways. The longer the runway, the less flaps it would drive. Less flaps meant higher rotate speeds. This in turn made the aircraft efficient after lift off with minimum drag. She would climb like a rocket without those darn doors out in the wind. But, depending on weight, you will encroach TSLW. Atmospheric conditions are also a factors.

 

High pressure altitudes and high temperatures are some big ones. An aircraft's weight and tire inflation plays a big part in the stress that a tire normally receives. An under inflated tire will receive a lot of stress and so would the adjacent tires because they are now taking on more weight than they should. Add that to the stress of a takeoff or landing roll and it can fail quickly. The placard speed is based on proper inflation. In the DC10, you compared the runway limiting weight against the climb gradient weight to attain a max weight and flap setting. If your actual weight was higher than the calculated TSLW, you would compare the runway limiting weight against the TSLW to get a new flap setting. Instead of 7 to 9 flaps, you would end up with 15.5 or 16 flaps. This gets you off the runway at a lower speed. I have had rotate speeds as high as 195 KTS. Ahh, the different variations of sounds the nose wheel made during takeoff until you lifted it off the ground. Then came the thumping and vibrations as it hit the spin pads in the nose wheel beneath you.

 

I'm not sure about how DCS simulates conditions in the A10 to give you a tire failure. But in actuality, tire failures are rare as long as they are properly serviced. You run more risk of deflation. In the wheel hub, there is a thermal/fusible plug. When the tire reaches a specific temperature or pressure, that plug will melt or blow to release the tire pressure. The number one cause of this is hot brakes. It can take up to 30 minutes before brake temps peak after heavy use.   

[Yurgon]

1 hour ago, g5flyer said:

I figured I would give you a little insight if you are really interested. [...]

 

Great info, thanks a lot for sharing!

[Hammer1-1]

2 hours ago, g5flyer said:

I know this is old,

I rarely worked on aircraft tires, but what little I do know is that if a tire is found to have lost any tire pressure its deemed a failure and needs to be replaced. This was in an RII I worked on with a 767 a few years ago. PSI in those tires are around 300 in those larger aircraft, and some Beechcraft 1900s Ive worked were around 200. Some tires are built to be rugged simply because of the terrain they are to be operating off of and can handle the stresses better. I have NEVER seen a tire failure in any aircraft so I dont know how many failures that equates to IRL experiences with others so understandably I have a hard time believing a tire will fail at 165kts on takeoff. Ive never touched an A-10 tire, much less know what their ratings are; I just dont think they would fail all of the time when an aircraft isnt generating that much heat in the tires on takeoff: tires are inflated to a point where they dont bulge as the flexing from the rubber on a tire in motion is what causes heat and stress failure. This is why the FAA mandates tires be replaced if they are found to have lost (IIRC) 5psi total.

 

But I digress...I dont know everything aviation.

Edited June 8, 2021 by Hammer1-1

[g5flyer]

27 minutes ago, Hammer1-1 said:

understandably I have a hard time believing a tire will fail at 165kts on takeoff

I agree, the lowest limit I've seen was 195kts.

A good accident to check out is the one from Nigeria Airways Flight 2120. The number 2 and 4 tires were too low for dispatch and they were out of nitrogen and blew it off. The famous 2008 one from Global Exec Aviation had tire inflation issues as well.

[Hammer1-1]

I was watching a youtube documentary on that piece the other day. It always amazes me what corporate would do just to save a few bucks, and an underinflated tire is an easy fix. Id have to dig around some, but Im willing to bet that was the reason why they changed the tire inflation regulations to be as strict as they are now. Nitrogen filled tires dont expand enough with a temperature increase which actually increase operating temperatures. Anyways, I think this is kind of a dumb thread to begin with. Ill get some info from one of my squadmates; got more than one who work on them IRL, so should be able to get some info from them.

 

My info says that the wheel speed Vne was more precautionary than an advisory. Its big issue was merely THAT at 38,000lbs WoW, and tire failure wasnt a big thing. NOW when it came to landing.......

Edited June 9, 2021 by Hammer1-1