Ground friction

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Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Ground friction

Post Artur »

Dear A2A, do u have any plan to rework and update ground friction, which is horrendous right now ?

alan CXA651
Senior Master Sergeant
Posts: 2321
Joined: 15 Mar 2016

Re: Ground friction

Post alan CXA651 »

Hi Artur.
I have had the B17 in FSXA for almost 5 years , never had this issue , are you using this in P3D , and what is the weight of the aircraft , i.e. at full full load , of mains/tokyo/bombbay she is hard to start moving initially , at light fuel she moves easy , also what surface are you on I.E. tarmac/concrete or grass , what are your power settings and boost setting and prop settings .
regards alan. 8)
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Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Alan, low fuel load ( without Tokyo tanks ), no bombs - so as for B17 standards very light plane.
As i saw on movies, real plane was moving by adding very little power, maybe 300 - 500 rpm, my plane will not move an inch until 25inches of manifold pressure.
Also during taxi she stops almost like no inertia force existing.
Saw also other users reported similar behaviour.

Asphalt or concrete surfaces only
My sim - P3D5.1 HF1

alan CXA651
Senior Master Sergeant
Posts: 2321
Joined: 15 Mar 2016

Re: Ground friction

Post alan CXA651 »

Hi Artur.
You mention HF1 , is that activesky weather engine for P3D , if so try the sim with P3D fair weather set , and see if you get same results , i have had ASN active sky for FSXA do strange things to the B17 if you get a corrupt weather download .
Also if you saw the same ww2 training video i saw , we dont know what the aircrafts weight was in that video.
Today i started my 4 engines , i had a lt fuel load no bombs , and i did not have brakes on , the aircraft started to roll and pick up speed , untill i put the brakes on , with the throttles set at the engine start position , to give min required oil pressure , so either the weather engine was giving you headwind , or P3D handles ground friction in a different way to FSXA.
regards alan. 8)
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Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Hi Alan, i refer to modern flights, they use low load and no turbo even, so conditions are comparable.
Regarding weather, ground friction issue is experienced on different airports ( payware and default ones ) and different weather conditions as i fly her often.
However i will try ur suggestion with fair weather - no active sky.

Edit - no noticeable difference with or without ActiveSky

alan CXA651
Senior Master Sergeant
Posts: 2321
Joined: 15 Mar 2016

Re: Ground friction

Post alan CXA651 »

Hi Artur.
If as you state refer to modern fllights , like 909 did before she crashed , they usually have enough fuel for 1 to 1 and a 1/2 hours , the A2A light fuel load can keep you airbourne for 4 to 5 hours , so they are a lot lighter than you think .
To get a good comparison look for ww2 training videos , as the aircraft would be a bit heavier , due guns and ammo and equipment , also ww2 radios and nav equipment was bigger and heavier than mordern radio/nav equipment thats needed to fly them today at airshows .
Also i am beginning to think that P3D itself is using ground friction differently than FSXA does for some strange reason , i cannot test it in P3D as i dont have that sim yet , but being a member of the 91st bombardment group , i can ask members who do have P3D and the recent release of the B17 for this sim , to see if they are suffering from your issue.
regards alan. 8)
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Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Appreciate Alan

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Masterius
Senior Airman
Posts: 179
Joined: 30 May 2019

Re: Ground friction

Post Masterius »

Seems to be something here.

Just ran a quick experiment to test this, using FSX:SE and P3Dv5 with identical parameters: A2A Accusim B-17, KBWI airport, Summer, clear skies, light fuel load, no Tokyo tanks, no bomb load, overhauled and warmed-up engines, and calibrated turbochargers.

In FSX:SE, with engines idling at just about 1,200RPM, the aircraft started a very slow roll, moving at 1MPH for about 10 seconds before reaching 2MPH.

In P3Dv5, the aircraft would not move at all until the engines reached around 1,500RPM, at which point it began a slow roll that quickly (well, quickly when compared to the FSX:SE acceleration) accelerated, reaching 6-8MPH within seconds.
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alan CXA651
Senior Master Sergeant
Posts: 2321
Joined: 15 Mar 2016

Re: Ground friction

Post alan CXA651 »

Hi Artur.
I sent an email to one of the 91st members who does scenery for FSX/P3D , and is a comuter software engineer , his reply and advice is this.

check the settings in P3D for Options > Realism – Attachments (lower right). The “ignore weight” and “Ignore forces” should NOT be checked.

For some reason, after the B-17 install to my P3DV4.5, these two boxes were checked, it caused erroneous speed behavior until I unchecked those boxes.

regards alan. 8)
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Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Hi Alan, those were really ticked, so have unticked those as u suggested.
Test flight with low load ( 1320 gal of fuel ) - she is as rock until 25 inches of manifold pressure and during taxi she starts to speed up.
:?

Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Masterius wrote:
19 Jan 2021, 16:56
Seems to be something here.

In P3Dv5, the aircraft would not move at all until the engines reached around 1,500RPM, at which point it began a slow roll that quickly (well, quickly when compared to the FSX:SE acceleration) accelerated, reaching 6-8MPH within seconds.
I am not the only one here :)

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Scott - A2A
A2A General
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Joined: 11 Feb 2004
Location: USA
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Re: Ground friction

Post Scott - A2A »

Since we do not have the ability to access and compile the ground friction code for P3D we just have to work with it. We were able to address this with our single engine airplanes that allows us to access more of the back end of Prepar3D, but our 4 engine airplanes use a different system which relies more on default Prepar3D physics.

Scott
A2A Simulations Inc.

Artur
Staff Sergeant
Posts: 285
Joined: 12 Jun 2015

Re: Ground friction

Post Artur »

Thanks Scott, sad news but at least know what to expect.

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