need evidence Question: Will our F16C Viper start to roll in idle without parking brake set?

[darkman222]

There is a question I have since a long time. I was expecting while development of the DCS F16 progesses that it will start rolling in idle without the parking brake set. It is said that without the parking brake the idle thrust is enough to push a clean jet forward. Or does our block have some kind of automatic brake that engages while in idle thrust? Or is it just not true that idle thrust is sufficient to get a clean jet rolling.

[AlexCaboose]

I've heard it's a thing IRL, but it doesn't generally happen in DCS except at extremely light weights (like after a sortie) or on an incline. An example of areas of where it does occur is the EOR by the 03L end of Nellis (low weight), or Incirlik EOR on the 23(?) end due to the incline.

[777coletrain]

It will only roll forwards though, if you are sitting on an upslope the F-16 will just sit there instead of rolling backwards.

[Sabre05]

I have had that happen on some parking spots that weren't fully level. I have made it a habit to set the parking brake now before I start the engine.

[Exorcet]

I think DCS has some parking state which adds extra friction to wheels when an aircraft isn't moving. Any stationary plane requires a bit of thrust to get rolling.

On the F-16 specifically, I know there is a GAO report from the 70's that complains about high idle thrust producing unacceptable taxi speed. Essentially the F-16 requires brake input to taxi slowly. The original plane would taxi up to 50 knots on idle power. This was reduced to 30 knots, and may have been reduced even more later, but I don't have documentation.

 

Since GAO documents are public they are safe to post under rule 1.16

https://www.gao.gov/assets/psad-77-41.pdf

[Nealius]

A couple years ago an IAF jet had a runaway taxi because of this. Though I have a hunch this is a bigger issue on the lighter variants. Isn't the Block 50 one of the heaviest Viper variants?

[darkman222]

18 hours ago, Exorcet said:

I think DCS has some parking state which adds extra friction to wheels when an aircraft isn't moving. Any stationary plane requires a bit of thrust to get rolling.

On the F-16 specifically, I know there is a GAO report from the 70's that complains about high idle thrust producing unacceptable taxi speed. Essentially the F-16 requires brake input to taxi slowly. The original plane would taxi up to 50 knots on idle power. This was reduced to 30 knots, and may have been reduced even more later, but I don't have documentation.

 

Since GAO documents are public they are safe to post under rule 1.16

https://www.gao.gov/assets/psad-77-41.pdf

This is the input/info I was looking for. Of course I cant provide evidence as a gamer. But having played almost every F16 sim that was out on the market, I have the feeling that ED might be interested into having a closer look at how the idle thrust vs the tire friction and the break away force (not sure if the translation is correct) with the F16 standing still are correlated.

In real life we have the friction and of course a much higher static friction that has to be overcome to get the jet moving. But from what I heared is that the idle thrust is sufficient to get the jet moving when not standing on the breaks. If the difference in weight between the many F16 blocks make the difference between having to stand on the breaks while in idle or not, I dont know.

Edited October 2, 2022 by darkman222

[Dragon1-1]

If you can get a hold of that GAO report, that could be good evidence. FYI, static friction doesn't matter much for things that are on wheels (at least as far as getting moving goes, static friction is how wheels get traction) - it's primarily the bearing resistance that has to be overcome, and that tends to be rather low. There's also rolling resistance, but it comes from tire deformation, not from friction (that's one reason why trains roll so well, steel wheels don't deform much), and it doesn't care if you're just starting to move or not.

Also, brakes, not breaks.

[silverdevil]

@Dragon1-1 lol with the spelling. i just read the GAO report @Exorcet posted. the document typist misspelled thrust (thurst)

Quote

Although landing any aircraft on an icy runway is hazardous, the F-16 may be more of a risk than other aircraft because of its current high idle thurst. Norway, in particular is concerned and had requested a feasibility study for the installation of a thrust reverser on the F-16/F100 engine.

i notice occasionally the roll. not sure of exact circumstances. i have gotten used to looking down to the left while on ground. one on my cars is stick. i have to pay attention in it too.