Questions about P-38 brakes

[DarkWolf29]

I was wondering about a couple things related to the P-38's brakes.

 

The first is when taking off, the pilot's notes in game say to hold the brakes and begin your run when you reach 54 inches of manifold pressure. Sometimes this is not possible as the aircraft seems to slip and start rolling before you ever reach 54 inches. I'm not 100% sure but it seems it might only happen on winter maps?  Is this something specific to the P-38's brakes or just general brake behaviour in cold weather?

 

The other thing is when you spawn in parked with the P-38, the tail will tend to rock up and down slightly. Even when the weather is calm and your engines are off its like someone is pushing the tail up and down a bit. I noticed if you release the parking break it will tend to rock a few more times then settle down and stop. If you set the parking brake again it will start the tail rocking again. Is this just a little bit of buggy behaviour or is there some explanation?

 

DW

[FeuerFliegen]

3 hours ago, DarkWolf29 said:

The first is when taking off, the pilot's notes in game say to hold the brakes and begin your run when you reach 54 inches of manifold pressure. Sometimes this is not possible as the aircraft seems to slip and start rolling before you ever reach 54 inches. I'm not 100% sure but it seems it might only happen on winter maps?  Is this something specific to the P-38's brakes or just general brake behaviour in cold weather?

 

I'd assume that because of colder weather, and therefore the air being denser, the engine is producing more power when compared to the same RPM/manifold pressure, as it is taking in both more fuel and air.

[Stoopy]

Running the engines up to get into the power band while you are holding the brakes is something that can be advisable with many aircraft and is generally done to shorten the takeoff run. It's not gospel to get to exactly XX amount of manifold pressure and with a long enough runway may not even be necessary.  The plane will let you know when it's ready to go, if she's pulling away then that's a more meaningful indicator than a gauge, let off the brakes and let her rip.

 

As for the P-38 rocking when you first spawn, it's just settling into the ground since the placement of the aircraft on the virtual map doesn't take into account the weight of the aircraft and travel of the simulated suspension. Think of it as placing the aircraft on its tiptoes at the very start so the tires are just touching the ground at the start of the mission. Then fuel and payload weight come into consideration as the mission parameters are processed, and the suspension compresses.  You can also see this take effect when you use the refuel / re-arm function.  Pretty nice touch I think.

 

Unless you want to go toward a more immersive explanation... It could be your virtual crew chief just jumped off the wing after getting you buckled in, or your virtual wingman and his virtual girlfriend were busy with themselves back there on that conveniently large and flat horizontal stabilizer... 

?

 

 

Edited July 26, 2020 by Stoopy

[6./ZG26_Klaus_Mann]

Most of the Brakes ingame operate at about half Power, in order to prevent skidding on our very skiddy surfaces, being Grass, Dirt, Snow and only very Occassionally Concrete.

I'm not sure how the Game handles Braking Power on the different Surfaces, but I guess I'm gonna give it a quick try.

[DarkWolf29]

Trying this a little more I had the brakes slip on a summer map, so maybe its not temperature related.

 

In regards to the rocking, this happens even before you start the engines while the aircraft is just sitting there. It doesn't seem to be related to the moment of spawn since you can re-engage the parking brake after sitting there for awhile and it will start again. I wonder if it has something to do with the kind of squishy landing gear the 38 has.

 

DW

[Art-J]

Squishy or not, that shouldn't happen. I noticed that too after the plane was released, but didn't realize it was happening only with parking brake on. Well, apart from great multirole plane, we've got a pertpetuum mobile then :D. Clearly a glitch of some sorts in the code, but since it doesn't affect other aspects of operations I never thought about it too much.

[DD_Arthur]

4 hours ago, Art-J said:

Squishy or not, that shouldn't happen. 

 

Er.....why not?  It's an aircraft with a tricycle landing gear arrangement designed to operate from grass fields.   I'm certainly not sure it's 'clearly a glitch of some sorts in the code'.

 

 

We haven't had any problems with planes 'skidding' whilst held on the brakes at takeoff either although we're still in October in our campaign so perhaps this will change as winter draws in.  Do pilot's notes really say to run the engines up to 54" before takeoff?  We're under the impression that they should be run up to 46" to get the turbos spinning up to speed before releasing brakes and commencing a takeoff run.

 

 

[DD_Fenrir]

21 hours ago, Stoopy said:

As for the P-38 rocking when you first spawn, it's just settling into the ground since the placement of the aircraft on the virtual map doesn't take into account the weight of the aircraft and travel of the simulated suspension. Think of it as placing the aircraft on its tiptoes at the very start so the tires are just touching the ground at the start of the mission. Then fuel and payload weight come into consideration as the mission parameters are processed, and the suspension compresses.  You can also see this take effect when you use the refuel / re-arm function.  Pretty nice touch I think.

 

This, +1000

[Bremspropeller]

 

The procedure is to hold the brakes until T/O MAP and RPM are reached. This includes 54''/3000.

[Art-J]

2 hours ago, DD_Arthur said:

Er.....why not?  It's an aircraft with a tricycle landing gear arrangement designed to operate from grass fields.   I'm certainly not sure it's 'clearly a glitch of some sorts in the code'.

 

Because, once again, we're talking strictly about situation when the plane has spawned "completely" (ie. fuel and payload weight has been calculated and applied, the plane has been "dropped" on the surface and settled for good), there is no wind set in the mission whatsoever, there is no rearming / refueling script running, all systems are cold and there is no "virtual wingman and his virtual girlfriend busy with themselves back there on that conveniently large and flat horizontal stabilizer" . To sum it up, there are no external forces acting on a physical object. Unless Mr Newton was wrong, P-38 should not be rocking all by itself then. 

 

I'm not surprised or bothered by possibility of some parts of simulation going a bit bonkers when ground or airspeed is zero, seen it in other games as well (i.e. controls shenanigans happening in DCS MiG-15 when it's stationary on the ground), it's not a big deal in flight simulator after all, but I can't agree the above behaviour is plausible when it's contradicting 1st and 2nd law of motion ;) .

 

Unless the "no wind" weather option in quick mission editor does still throw in a bit of a wind, then OK, the plane might be moving, but in that scenario we would be facing a different glitch, related to the editor itself.

 

Haven't flown the Lightning for many weeks, but I'll take a look at it again when I'm back at home. No idea how to test it in full mission editor though.

Edited July 27, 2020 by Art-J

[Art-J]

So after a quick test on Rheinland map, It seems the rocking is airbase dependent (or maybe parking spot dependent?) for some mysterious reason. Summer season, no wind (at least that's what the quick editor says...), minimum fuel (which makes the problem more visible), results are:

a) Melsbroek airfield - the plane settles after a few oscillations and stays still;

b) Eindhoven airfield - the plane keeps on rockin'.

 

Parking spots were grassy in both cases, so undefined something else is a factor.

[FeuerFliegen]

On 7/26/2020 at 9:14 AM, 6./ZG26_Klaus_Mann said:

Most of the Brakes ingame operate at about half Power, in order to prevent skidding on our very skiddy surfaces, being Grass, Dirt, Snow and only very Occassionally Concrete.

I'm not sure how the Game handles Braking Power on the different Surfaces, but I guess I'm gonna give it a quick try.

 

That makes sense that they don't operate at full power... if I have a short runway and need to stop as soon as possible once I touch the wheels down, I'll hold down the brakes 100% before the wheels even touch the ground; and I'd assume that in real life, that'd cause quite a different landing than the relatively smooth one it was.

 

It'd be nice if braking was a little more realistic in some aspects like that.

[Soilworker]

I heard they nerfed the brakes because people were prop striking, understandable if you're only using a button but I really wish they'd make a realism option instead. 

[LukeFF]

8 hours ago, Soilworker said:

I heard they nerfed the brakes because people were prop striking, understandable if you're only using a button but I really wish they'd make a realism option instead. 

 

That's been neither confirmed nor denied.

[FeuerFliegen]

18 hours ago, Soilworker said:

I heard they nerfed the brakes because people were prop striking, understandable if you're only using a button but I really wish they'd make a realism option instead. 

 

ah, yeah it would be difficult with just a button.  I have Virpil rudder pedals which work great as toe brakes, but unfortunately for me, planes like Tempest, Spitfire, and various VVS planes, I only have a button to use for the brakes, which can be a pain especially considering how difficult the Spitfire can be to taxi.

[Soilworker]

16 hours ago, LukeFF said:

 

That's been neither confirmed nor denied.

 

Good to know, cheers Luke. 

6 hours ago, SCG_FeuerFliegen said:

 

ah, yeah it would be difficult with just a button.  I have Virpil rudder pedals which work great as toe brakes, but unfortunately for me, planes like Tempest, Spitfire, and various VVS planes, I only have a button to use for the brakes, which can be a pain especially considering how difficult the Spitfire can be to taxi.

 

Yeah same here, Slaw RX Vipers and a freakin' button but I'm currently building a brake lever for my (modded) G940, just waiting on a couple of electronic parts and coding from my dad (on the other side of the world ?) and then it should be up and running in the next couple of weeks, can't wait!