Wheels stuck to the floor?

Hi All,

I've been curious about this for some time... The A10 has no parking brake but why does the nose oleo compress and then rebound when you apply power to move off? It behaves as if a brake is applied then released, or it's jumping a choc. Can't find anything after a search, so sorry if this has been covered.

Best wishes,

Luke

I think its more like the nose wheel is being forced into the ground as the force from the engines has yet to cause it to begin moving and up until that point the nose gear is compressed by the force acting on it.

Now this could very easily be simply a flaw in the modeling of the ground handling since the A-10C has neither a parking brake nor any chocks available to it in this sim.

I would guess the initial wheel friction being strong enough to have applied thrust moving the whole ship nose down. Since the center of gravity is lower than the thrust sources, the force vector pushes the plane overhead the C.G., resulting in a nose down swing. This of course ceases when wheel friction is overcome and thrust then is converted into moving the aircraft across the ground.

I expect it's got more to do with the quirky ground/wheel interaction modelling. The wheels would offer a small amount of rolling resistance but not enough to cause such a compression followed by such a sharp release. I've just watched a couple of clips on YouTube and the A10 doesn't behave like this without brakes being applied.

Never mind, it's not the end of the world though :-)

And I thought I was anal... :music_whistling:

And I thought I was anal... :music_whistling:

Don't worry. Around here, anal retentiveness is graded on a curve. ;)

I'm inclined to believe it is inertia, combined with the asymmetric thrust vector. Add thrust - nose down - overcome inertia - nose up.

That's my excuse and I am sticking to it!

The OP has a point I think which is more related to the ground and the way it's simulated... sticky somewhat..

Same in other aircraft especially the F-15, you have to gently increase power until it "breaks" free of the friction..

Just my thoughts anyway.

And I thought I was anal... :music_whistling:

Perhaps you're just an anus.

Perhaps you're just an anus.

Take a chill pill =p

Crap... Sorry, I probably shouldn't be speaking back to the Chief Instructor:megalol:

And try the F86 and its ground handling. It's can be like ice skating after you land. Definitely no sticking there =]

It is not:

• Inertia
  
• Related to the CoG
  
• Unbelievable
  

You have static friction and dynamic (rolling) friction. The static friction that you have to overcome to start rolling is significantly higher than the dynamic friction you have to overcome to keep rolling.

It can take a good burst of power to start an aircraft rolling, but after that many aircraft roll and even accelerate on idle power, especially when light. In some aircraft, taxiing with an engine or two not started is an option sometimes used to save brake wear when light. With all engines on idle, you'll have to ride the brakes to keep the taxi speed down. This is something you want to avoid to save brake wear, especially if you have carbon brakes which wear by number of applications rather than by how hard they are used.

The thrust line of the engines is above the wheels, which is why you get a nose down moment which compresses the nose gear oleo (and obviously, though to a lesser degree, extends the main gear oleos).

Cheers,

/Fred

I thought the A-10 did have a parking brake. I know the F-15 does.

I thought the A-10 did have a parking brake. I know the F-15 does.

Nope, which is why the lack of chocks in DCS is particularly annoying.

It is not:

 

• Inertia
  
• Related to the CoG
  
• Unbelievable
  

You have static friction and dynamic (rolling) friction. The static friction that you have to overcome to start rolling is significantly higher than the dynamic friction you have to overcome to keep rolling.

 

It can take a good burst of power to start an aircraft rolling, but after that many aircraft roll and even accelerate on idle power, especially when light. In some aircraft, taxiing with an engine or two not started is an option sometimes used to save brake wear when light. With all engines on idle, you'll have to ride the brakes to keep the taxi speed down. This is something you want to avoid to save brake wear, especially if you have carbon brakes which wear by number of applications rather than by how hard they are used.

 

The thrust line of the engines is above the wheels, which is why you get a nose down moment which compresses the nose gear oleo (and obviously, though to a lesser degree, extends the main gear oleos).

 

Cheers,

/Fred

Thanks Fred,

Everything you've said is technically correct but it's not sufficient to cause the nose oleo to compress on breakaway - at least not to the degree that is modelled in DCS. The thrust vector arm and coupling will cause a theoretical pitching down moment before the wheel starts to roll, but unless the nose wheel tyre is on something very soft, the oleo compression resistance will resist it for the most part - particularly on a hard ramp surface such as in DCS. Watch this video clip and you'll see a real A10 start its taxy roll. There is no real perceptible compression of the nose leg prior to the aircraft moving.

I just think it's over done in DCS!

Cheers

Take a chill pill =p

 

Crap... Sorry, I probably shouldn't be speaking back to the Chief Instructor:megalol:

 

And try the F86 and its ground handling. It's can be like ice skating after you land. Definitely no sticking there =]

Yeah sorry - perhaps my response was a bit harsh! I just want this sim to be as good as it can be - so I don't think it's fair to call me anal just for asking a question :-)

I love this plane