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Author Topic: P-38 and Gravity  (Read 1565 times)

Offline Anodizer

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Re: P-38 and Gravity
« Reply #15 on: February 22, 2012, 03:41:25 PM »
Quote from: STEELE on February 22, 2012, 01:41:23 PM
If you notice the good 38 guys stay above 10k and only come down for a good shot, then zoom back up.    ^__^

You are obviously noticing what you want to notice(which is not reality)..  Most guys who fly 38's full time do so because of the challenge and don't subscribe to the typical boom-zoom-run-rinse-repeat theory..  If you see guys do that in 38's, they are doing it in every other ride as well and the 38 is NOT their main plane..  They primarily use it as a bomb truck and then attempt their hand at dog fighting when all their bombs and rockets miss only to compress and crash into the ground..  These are the same people who fly with stall limiter on while not even knowing it exists and have no idea what trim actually does..

Spend some time watching guys like Shuffler or Corky..  They never go much beyond 5 or 6k..  Hell, our entire squad never goes much higher than 5 or 6 k!!!  And whether they say they are good or not, they are in fact good down on the deck in the 38..  So yeah, you don't really know what you're talking about..  Just so you know...   :D



 
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Offline Ack-Ack

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Re: P-38 and Gravity
« Reply #16 on: February 22, 2012, 05:05:06 PM »
Quote from: TwinBoom on February 22, 2012, 03:05:55 PM
i often use them as air break for a hard breaking turn works well

It actually doesn't as the dive flaps do not generate enough drag to slow you down, so they cannot be used as an air break.  However, at high speeds the dive flaps can aid in a turn as the lift generated by the dive flaps helps bring the nose around in the turn and retracted as soon as you past the apex of the turn.

ack-ack
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Offline curry1

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Re: P-38 and Gravity
« Reply #17 on: February 22, 2012, 07:10:37 PM »
I am so confused first they dont create enough drag to brake you but then they apparently make enough lift to turn your nose noticeably.  You need drag to create lift so...
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Offline JOACH1M

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Re: P-38 and Gravity
« Reply #18 on: February 22, 2012, 07:50:13 PM »
If you compress in a 38 your doing something wrong. :)
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Offline Ack-Ack

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Re: P-38 and Gravity
« Reply #19 on: February 22, 2012, 07:57:29 PM »
Quote from: curry1 on February 22, 2012, 07:10:37 PM
I am so confused first they dont create enough drag to brake you but then they apparently make enough lift to turn your nose noticeably.  You need drag to create lift so...

The dive flaps weren't designed to create drag and slow the plane down like dive brakes, the dive flaps would change the air flow that basically altered the center of pressure distribution to help counter the nose tuck encountered when the P-38 entered into a compressability state.  There is a more technical description but in basic layman terms, that's what the dive flaps did.

As you can see from the design, it would be very inefficient in slowing down the P-38.



What the dive flaps look like when deployed.


The loss of energy/speed described by pilots was caused by the nose pitching up when the flaps were deployed, not by the drag caused by the flaps themselves. 

ack-ack
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Offline Charge

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Re: P-38 and Gravity
« Reply #20 on: February 23, 2012, 01:52:59 AM »
Nice info ackie.  :aok

So the actual problem in P38 was that as the main plane compressed there was simply not enough elevator authority to bring the nose back up, i.e. the same as in P47? So the compression problem was different to that of e.g. 109 which suffered from excessively heavy controls or you could say that 109 had not a "compression" problem but just suffered from heavy controls. Or did the P38 suffer also from this in high speed dive?

-C+
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Offline Rino

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Re: P-38 and Gravity
« Reply #21 on: February 23, 2012, 03:35:26 AM »
Quote from: STEELE on February 22, 2012, 01:41:23 PM
If you notice the good 38 guys stay above 10k and only come down for a good shot, then zoom back up.    ^__^

      That would explain why my squaddies all crawl around at low alt then  :D
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Offline Grape

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Re: P-38 and Gravity
« Reply #22 on: February 24, 2012, 02:24:06 PM »
When I compress in a 38, I stop drinking and go to bed...
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Offline Murdr

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Re: P-38 and Gravity
« Reply #23 on: February 24, 2012, 03:17:19 PM »
Quote from: Charge on February 23, 2012, 01:52:59 AM
Nice info ackie.  :aok

So the actual problem in P38 was that as the main plane compressed there was simply not enough elevator authority to bring the nose back up, i.e. the same as in P47? So the compression problem was different to that of e.g. 109 which suffered from excessively heavy controls or you could say that 109 had not a "compression" problem but just suffered from heavy controls. Or did the P38 suffer also from this in high speed dive?

-C+

The P38s specific problem were the shockwaves that formed on the top fore of the wing due to it's thick foil profile.  The result was basically positive pressure on the TOP fore of the wing and negative pressure on the top aft causing the "nose tuck".  This also disturbed airflow to the rear surfaces.  The dive flaps were to help change the airflow to generate some lift at the fore of the wing.  So yes it was different from the 109's problem.  From what I understand compression was a generic term used to describe similar high speed problems whos causes weren't fully understood at the time.
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Offline Ack-Ack

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Re: P-38 and Gravity
« Reply #24 on: February 24, 2012, 03:27:01 PM »
Quote from: Murdr on February 24, 2012, 03:17:19 PM
The P38s specific problem were the shockwaves that formed on the top fore of the wing due to it's thick foil profile.  The result was basically positive pressure on the TOP fore of the wing and negative pressure on the top aft causing the "nose tuck".  This also disturbed airflow to the rear surfaces.  The dive flaps were to help change the airflow to generate some lift at the fore of the wing.  So yes it was different from the 109's problem.  From what I understand compression was a generic term used to describe similar high speed problems whos causes weren't fully understood at the time.

How's the rock star life?  Getting bored of touring, free drinks and loose groupies yet?

ack-ack
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Offline Murdr

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Re: P-38 and Gravity
« Reply #25 on: February 24, 2012, 03:36:08 PM »
Quote from: Ack-Ack on February 24, 2012, 03:27:01 PM
How's the rock star life?  Getting bored of touring, free drinks and loose groupies yet?

ack-ack
Not yet!!!  Getting ready to play out tonight.  But we gotta keep the groupie thing on the down-low...My g/f wouldn't like that  :lol
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Offline Geaux

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Re: P-38 and Gravity
« Reply #26 on: February 29, 2012, 09:05:16 PM »
I try to cut throttle and use the rudder to side "crab" during a dive to keep the speed just about 400 IAS.  I do not usually use the trim tab because with enough altitude I can pull out of the dive without it.  If I am too low I just become a yard decoration.  But then again I kinda suck at flying a 38 so...
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Offline Plazus

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Re: P-38 and Gravity
« Reply #27 on: February 29, 2012, 09:15:29 PM »
I prefer trimming nose down in a dive. Helps me fly faster and auger harder, which is important for part distribution.
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Offline BamBam

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Re: P-38 and Gravity
« Reply #28 on: March 09, 2012, 11:48:15 AM »
Quote from: Grape on February 24, 2012, 02:24:06 PM
When I compress in a 38, I stop drinking and go to bed...

<  :aok  I have a problem with drinking and ending up @ 49k.  lol
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Offline uptown

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Re: P-38 and Gravity
« Reply #29 on: March 10, 2012, 10:07:11 PM »
Quote from: JOACH1M on February 22, 2012, 07:50:13 PM
If you compress in a 38 your doing something wrong. :)
:rolleyes:   
« Last Edit: March 10, 2012, 10:17:59 PM by uptown »
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