Author Topic: Did Enemy Have Compression Problems?  (Read 456 times)

Offline Mongoose

  • Silver Member
  • ****
  • Posts: 1518
      • Kentwood Station
Did Enemy Have Compression Problems?
« on: October 31, 2022, 10:36:19 PM »
I know the early P-38 and P-47 models had problems with compression and control lock in dives, until the engineers figured out how to fix it.

Did planes from other countries have similar problems with dive speed? 
My Aces High fan site:
www.kentwoodstation.com

Offline TryHard

  • Copper Member
  • **
  • Posts: 200
Re: Did Enemy Have Compression Problems?
« Reply #1 on: November 01, 2022, 12:43:49 AM »
Short answer: Yes

Me109 comes to mind right away

Offline Arlo

  • Radioactive Member
  • *******
  • Posts: 24630
Re: Did Enemy Have Compression Problems?
« Reply #2 on: November 01, 2022, 01:47:48 AM »
Physics be universal, eh?  :)

Offline TryHard

  • Copper Member
  • **
  • Posts: 200
Re: Did Enemy Have Compression Problems?
« Reply #3 on: November 01, 2022, 11:01:29 PM »
Physics be universal, eh?  :)
Until you run into a blackhole or Nazi anti-gravity yes a I believe something to that effect.

Offline TryHard

  • Copper Member
  • **
  • Posts: 200
Re: Did Enemy Have Compression Problems?
« Reply #4 on: November 01, 2022, 11:02:35 PM »
I don't recall the P47 ever having compressabilty problems, It performs the best with full power pointing straight at the ground regardless of airspeed.

Offline Drano

  • Gold Member
  • *****
  • Posts: 3946
Re: Did Enemy Have Compression Problems?
« Reply #5 on: November 01, 2022, 11:17:30 PM »
Later models (think M and N) had a similar dive recovery flap to the ones on the later P-38J's and all of the L's

Sent from my SM-G991U using Tapatalk

"Drano"
80th FS "Headhunters"

S.A.P.P.- Secret Association Of P-38 Pilots (Lightning In A Bottle)

FSO flying with the 412th Friday Night Volunteer Group

Offline DaddyAce

  • Silver Member
  • ****
  • Posts: 1253
Re: Did Enemy Have Compression Problems?
« Reply #6 on: November 04, 2022, 09:24:18 AM »
M has dive brakes in game, does N also have them in game?

Offline TryHard

  • Copper Member
  • **
  • Posts: 200
Re: Did Enemy Have Compression Problems?
« Reply #7 on: November 04, 2022, 06:31:14 PM »
M has dive brakes in game, does N also have them in game?
M and N both have dive  flaps not really dive brakes, they make the elevator surfaces lighter at high speeds delaying compression by changing the airflow impacting the horizontal stab/elevators. They actually cause very little drag when deployed

For the P47s they are only needed when diving from 20k with WEP straight down at 600mph+. On the P38L they are A LOT more useful and offset the main weakness of the 38 (low critical mach number).
« Last Edit: November 04, 2022, 06:33:02 PM by TryHard »

Offline Drano

  • Gold Member
  • *****
  • Posts: 3946
Re: Did Enemy Have Compression Problems?
« Reply #8 on: November 04, 2022, 07:11:22 PM »
People get confused even tho they are marked in the controls setup as such they are most definitely NOT dive brakes. These things aren't gonna slow you down!

Sent from my SM-G991U using Tapatalk

"Drano"
80th FS "Headhunters"

S.A.P.P.- Secret Association Of P-38 Pilots (Lightning In A Bottle)

FSO flying with the 412th Friday Night Volunteer Group

Offline MiloMorai

  • Platinum Member
  • ******
  • Posts: 6743
Re: Did Enemy Have Compression Problems?
« Reply #9 on: November 04, 2022, 10:51:03 PM »
P-47s had low Mach numbers compare to Spit and Mustang.

Offline drgondog

  • Copper Member
  • **
  • Posts: 317
Re: Did Enemy Have Compression Problems?
« Reply #10 on: February 12, 2023, 10:19:26 AM »
Both P-47 and P-38 as well as Bf109 and Fw 190 had same issues with compressibility - primarily manifested in nose down pitching moment as center of pressure moved during transonic to supersonic flow. The issues were compounded by wake immersing h.Stab and blanking elevator authority until Mach number decreased below critical mach. The Mustang avoided the need for dive flaps because the CP was already 10-15% aft of the classic NACA 23xxx and similar airfoils of the day. The P-47D wing however was closer to the P-51 wing with max t/c very similar (30% vs 37%) and Root T/C of 14% vs 16.5%, and had a simiar Mcrit.

The P-47D-30 had first dive flap installation, the P-38J-25 was first production dive flap installation, but kits were sent for J-15 (One such delivery famously short circuited by RAF on way to ETO (in Feb 1944??)

NAA installed a dive flap on P-51B-10-NA but found no material benefits to dve control 'without' flaps.
Nicholas Boileau "Honor is like an island, rugged and without shores; once we have left it, we can never return"

Offline Vulcan

  • Plutonium Member
  • *******
  • Posts: 9699
Re: Did Enemy Have Compression Problems?
« Reply #11 on: February 12, 2023, 05:10:53 PM »
....and then there's the Brewster.

Offline icepac

  • Platinum Member
  • ******
  • Posts: 6607
Re: Did Enemy Have Compression Problems?
« Reply #12 on: March 12, 2023, 10:29:48 AM »

The P47 had compressability issues at much higher speeds....................bec ause it was faster.