P51 flaps down and other default settings...

[Bilbo_Baggins]

Gentlemen,

 

A few questions regarding default startup peculiarities:

 

Why is it the P51 starts with flaps fully down?

 

Some similar machines like Yak 7 start with full prop rpm, but Lagg 3 and Yak 1b start with minimum?

 

 

 

 

 

 

[[DBS]Browning]

Before you start the engine, the 51 lacks the hydrolic pressure needed to raise the flaps. 

Lowering the flaps is part of the shutdown procedure to prevent anyone standing on them. It may also happen as pressure in the hydrolic system lowers with time. 

 

Edited April 29, 2021 by [DBS]Browning

[Bilbo_Baggins]

13 minutes ago, [DBS]Browning said:

Before you start the engine, the 51 lacks the hydrolic pressure needed to raise the flaps. 

Lowering the flaps is part of the shutdown procedure to prevent anyone standing on them. It may also happen as pressie in the hydrolic system let's with time. 

 

 

Awesome detail and info, cheers.

[RyanR]

The other cool thing is that the landing gear "doors" on the P-51 are hydraulic as well, so those are open when the plane has no hydraulic pressure. When you start the engine, those will close. Just an amazing attention to detail by the developers.

 

-Ryan

[Jade_Monkey]

Based on this video, it looks like real life flaps retract much faster than in game, which take significantly longer.

 

Not a huge issue but it always surprised me how long they take.

 

https://youtu.be/PXTIFCWkVGg

 

 

[FlyingH]

@Jade_Monkey could that depend on the throttling up that the pilot did once the engine started? He must have got to at least 1000rpm at once.

[Jade_Monkey]

38 minutes ago, FlyingH said:

@Jade_Monkey could that depend on the throttling up that the pilot did once the engine started? He must have got to at least 1000rpm at once.

 

It's a good thought, but I dont know the answer. Not my area of expertise.

Maybe someone here knows more about how the revs would impact the pressure in the hydraulic system.

[Mitthrawnuruodo]

42 minutes ago, Jade_Monkey said:

Maybe someone here knows more about how the revs would impact the pressure in the hydraulic system.

 

The manual says that two thousand rpm is needed for full hydraulic pressure.

 

There's also a hydraulic pressure accumulator and even an optional hand pump (plus a vast number of rather complicated fittings), so the conditions aren't necessarily the same for every engine start. Seems that the results could vary.

[SShrike]

There is a difference of about 77 years  between the game model and the video. I would guess the mustang has a refurbished or updated hydraulic system. 

[the_emperor]

Would damage (failure) to the hydraulic system force the flaps and/or landing gear down? or are they additionaly locked when up?

 

Cheers

[Art-J]

With hydro pressure lost the gear is still mechanically locked and won't extend until the gear lever is put in down position. Flaps - I don't know if they have a mechanical lock, but certainly won't extend when subjected to airstream in flight, you need a lot of hydro pressure to do that.

 

Actually, about flaps drooping on their own when the plane is standing on the ground with hydro released, there was a long debate about the subject on WIX forum (I think?) and apparently they don't really do that all that much in real life unless the plane is sitting on the ground for a really looooong time, or someone pushes them down. They're just not heavy enough to push the oil through the installation that quickly on their own.

[Gambit21]

I have hundreds of WWII photos from the 352nd. Mustang flaps were rarely in the down position when parked. I won’t say ‘never’ as there are a few exceptions, but it’s not the norm.

[Stiggles]

 

11 hours ago, Gambit21 said:

I have hundreds of WWII photos from the 352nd. Mustang flaps were rarely in the down position when parked. I won’t say ‘never’ as there are a few exceptions, but it’s not the norm.

 

Would it be possibly because the planes were on constant turnaround at Bodney/Y-29/Etc., and they didn't sit long enough for the flaps to lose enough pressure to drop before another sortie? I don't know how long it takes for that system to go limp, but it probably isn't instantaneous.

Off topic question 1: I'm guessing the George Preddy Profile Pic is from those photos?

Off topic question 2: Is there a single, public location for those pictures? Just finished reading "Fighter Squadron", and I wanted to look at some better quality versions of the pictures in the book.

[Gambit21]

14 hours ago, Stiggles said:

Would it be possibly because the planes were on constant turnaround at Bodney/Y-29/Etc., and they didn't sit long enough for the flaps to lose enough pressure to drop before another sortie? 

 

Possibly, I'm not sure how long it would have to sit before they dropped, and really if there are no leaks they shouldn't drop regardless.

 

 

Quote

Off topic question 1: I'm guessing the George Preddy Profile Pic is from those photos?

 

It's Preddy, but just from a photo I grabbed online.

 

Quote

Off topic question 2: Is there a single, public location for those pictures? Just finished reading "Fighter Squadron", and I wanted to look at some better quality versions of the pictures in the book.

 

I got many of them from Sam Sox (the 352nd photo historian) over the years, as well as from the 2 books that the squadron published. (out of print)

The Bluenosed Bastards of Bodney, (big, blue hardcover squadron history, not the publicly available small book by Ivie) and Bluenoser Tales.

 

Jay Stout is a good guy, he's helped with some Hornet stuff and other research.

 

 

 

Edited May 5, 2021 by Gambit21