Aces High Bulletin Board
General Forums => Aircraft and Vehicles => Topic started by: stantond on October 21, 2002, 11:06:48 PM
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Didn't the P38L have high speed flaps? Seems like everything I have read seems to indicates that. Just curious.
Malta
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Yes, it had dive flaps that were designed to aid in high speed dive recovery. The landing flaps could be set to a manoeuver setting below 250 mph. If you're thinking of improving turn performance, they won't help much above that speed anyway, cause you'll be blacked out, regardless.
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Did the RL dive flaps produce drag? I don't detect any difference in level speed when AH flaps are deployed. (Or, maybe the effect is very small??) Anyway, can't see a reason to retract them.
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Originally posted by popeye
Did the RL dive flaps produce drag? I don't detect any difference in level speed when AH flaps are deployed. (Or, maybe the effect is very small??) Anyway, can't see a reason to retract them.
Yes, they did generate drag, and shifted the center of lift forward along the chord, inducing pitch-up. This then would cause a hands-off, 3 G pullout. As modelled right now, the AH dive recovery flaps do none of the above.
My regards,
Widewing
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Yeah, they just "exist".
maybe time to fix old planes before adding new ones HTC?
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I thought the purpose of those flaps was to increase it's compression speed .
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Samm,
If you flapped them harder you would go faster?
// fats
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The dive recovery flaps did not change the speed where the "tuck under" started. But because they added that positive pitch as Widewing noted, the plane could safely reach 20-30mph higher speed in the dive and therefore also steeper dives were possible. Also drag caused by this device helped to keep the plane out of trouble.
gripen
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(http://home.cfl.rr.com/wraithfleethq/diveflps3.jpg )
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=26424&highlight=dive+flaps
http://www.hitechcreations.com/forums/showthread.php?s=&threadid=27973
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It would be really nice if HTC would fix the dive flaps on the P-38.
I'm glad I found this thread, I just started learning the 38 in AH and was a little frustrated that the dive flaps made no significant difference. In Air Warrior they worked quite well, like a speed brake and were useful in situations where you wanted to slow down quick.
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Then again, why we want the dive flaps for the P38 fixed is just because we want our planes to be far superior to everything else and so on, not something to do with realism or anything like that at all :rolleyes:
(for those of you who have no idea of what I am talking about, ignore it)
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Just recently the light went out for dive flaps indicator. Now nothing about them works. :D
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Evil wilbus...just evil ;)
There were 2 biggest gripes ive had with the 38 model since I started playing:
Damage Model
Flaps. (Dive Flaps and the $#@@ autofowlerflapretract)
Took 10 or so tours to get the damage model fixed. Perhaps we have to wait 10 more for the flaps ?
:(
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While the P-38 "Dive Flaps" do provide the needed forward lift as WideWing noted, they also have a few other "Nifty" characteristics that should be noted.
#1 they refuse to deploy at high speed, as the electric drive motor WILL NOT and does not have the power to put them out.
#2 If Dive speeds are exceeded, they tend to be either driven back, or the actuation arm bends or breaks all together resulting in a terminal dive.
#3 They WERE NOT standard equipment on the J and L, and in some cases were even removed to save maintenance headaches.
One of the Lightnings I have in our shop now suffered the failure noted in #2... it's leading edge and most of the wing is less than a foot thick... (Nose to Trailing Edge) Another, is an L, which does not have Dive Flaps... they are there, just faired over, and the work was done during the war as judged by markings on the metal. Just an FYI for ya'll.
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So,
I guess what you are saying is that the work at NACA to develop the dive brakes was not implemented or utilized. I never heard that before. I believe that hydraulics replaced the electro-mechanical actuators. Course all that is from reports and not actual aircraft.
That said, the aircraft models used in AH are just that. What I was originally referring to was a high speed (>300 ias) flap setting. Seems like I rember reading about one and Air Warriors 38J had a high speed flap setting (and dive brakes). Not that the P38 in AW was any more realistically modeled than the one in AH.
Malta
p.s. I have a fondness for the P38. It was the first AW plane I was able to get a five kill flight out of.
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P-38 has dive flaps, not dive BREAKS.
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Evil wilbus...just evil
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Stop posting under two name dweeb!:p
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according to this article, the Fowler Flaps on the p-38 can be used up to 250mph. The p-38 also had an "aileron boost". Don't know if that is included in AH.
p-38 (http://www.flightjournal.com/articles/p-38_lightning/p-38_lightning_1.asp)
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Who ya talking to Lazer?
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From everything I have read (got references if anyone is interested... except for *you* TAC) the P38J and later combat versions were equipped with a dive brake. This was not part of the flap system but an add on. The brakes were located beside the engines on the underside of the wing (similar to what AH shows offline from an exernal view).
So, is the consensus that the high speed flaps (ie AW P38J) were not physically used? It does seem the dive brake in AH does not seem to work. Maybe that's a feature of the game?
The maximum speed before compressibility as printed was 0.67 Mach (~450 mph at sea level). For what that bit of trivia is worth. I really hope this thread is not attracting morons.
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The P-38's "Dive Flaps" (or compressibility flaps per Kelly Johnson) are located in the the lower side of the Outboard Wing panels, About a foot behind the spar and approximately 1 foot out board of the wing panel joint. They are about 4 feet long, and are at their widest approxiamtely 1 foot. The work in a simple form, they are hinged in the front, and about 1/2 way back, the forward winged panel swings down and forward, while the aft remains parallel to the wings lower surface. This simple two piece flap is actuated by an ELECTRIC motor, the prototype was hydraulic. It is NOT a DIVE BRAKE, but merely a small flap that restores lift to the wing being lost to the effects of compressibilty. There are two positions, fully deployed, or fully retracted. They are to be deployed immediately upon entering a dive, or shortly there after. These "dive recovery flaps" were installed as standard equipment on the J-25 series and continued through out production. They are succeptible to failure at high speeds, and have great difficulty deploying at a high rate of speed, as the electric motor is VERY small. Lastly, the electro/hydraulic controls you are refering to, Stantond, are located in the WING FLAP Drive motors, and the Boosted Ailerons. Hope this helps, will try to remember to take some pics of some real ones tomorrow, and bring home the manual.
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This is a basic view of the flap from the underside of the wing... it is just a drawing but gives an accurate placement.....
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Here, found an actual photo with none other than Kelly Johson included! See, the flap is so simple, and is basically attached to the exterior of the wing... It is deployed in the photo...
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"The Mighty Eighth War Manual" by R. Freeman contains some information about problems with the dive recovery flaps:
"The 479th Group received two aircraft with such flaps in August 1944 - at which time it was the last P-38 equipped group in VIII FC. After some hours flying with them they complained that the flaps continually broke down; one aircraft had needed repair nine times. The Group arranged to exchange these aircraft for two without flaps."
Kelsey's accident was caused by prototype version of the dive recovery flaps (hydraulic operated as Bodhi noted); the flaps failed to work when Kelsey was testing if they can be opened at high speed when compressebility effects started. Kelsey did all his tricks but could not stop "tuck under" and other wing failed. Somehow Kelsey got out of the plane.
This (http://naca.larc.nasa.gov/reports/1947/naca-rm-a7c24/) report contains some info about the dive recovery flaps, this page (http://naca.larc.nasa.gov/reports/1947/naca-rm-a7c24/index.cgi?page0023.gif) shows how "tuck under" developed and how the dive recovery flaps countered it.
gripen
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Here is a link with some information on P38 testing:
http://oea.larc.nasa.gov/PAIS/WWII.html
The "dive recovery flaps" (what I call dive brakes per AH, AW, etc) were not what I was originally asking about. Although I am leaning towards the idea that there were no high speed flaps (such as the P51's use). It would satisfy my curiosity to see that in print though.
Some of this (obsession?) comes from Air Warrior. I was generally impressed with the detail and research of the flight models in the game. That is not to say they were 100% historically accurate. AW was, like AH, a game and some things were “embellished” to keep the players happy.
Your info is very cool BTW Bodhi.
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OK,
Figured out how the dive flaps (what I have been calling dive brakes) work. They work similar to how historical records state. While they don't pull the nose up, they do allow the nose to be pulled up with trim.
Without the dive flaps, trim won't pull the nose up after compression. With the dive flaps, elevator trim will get the nose up. The dive flaps don't provide any enhanced manueverability or slow the plane down. They break up the air flow and allow the control surfaces to work (elevator trim at least).
Check it out (offline) and see what I am talking about.
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the only difference i've seen with dive flaps on p38 in AH is the way they help stabalize the plane when fighting a zeke at low alt.,low speed. suprised a few ppl with it.:cool: ;)
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Well here is what I found on the 38:
The L-5 has
- different engines (but same ratings, yet some sources say that the L's engines could run WEP at 1725 HP, rather than 1600)
- landing light inset in leading edge of left wing rather than a retractable light under wing as on the J
- improved fuel system
- tail warning radar
- improved turbosuperchargers
- hard points for Christmas tree rocket launchers (standard)
The L was the definitive Lightning, and met practically all the expectations originally conceived and exceeded others not originally conceived, such as photo-reconnaissance and formation bombing.
Here's a quote by Capt. Stan Richardson:
"The P-38J25-LO and P-38L's were terrific. Roll Rate? Ha! Nothing would roll
faster. The dive recovery flaps ameliorated the "compressibility" (Mach
limitation) of earlier Lightnings. An added benefit of the dive recovery
flaps was their ability to pitch the nose 10-20 degrees "up" momentarily
when trying to out turn the Luftwaffe's best, even when using the flap
combat position on the selector. Of course the nose "pitch-up" resulted in
increased aerodynamic drag, and must be used cautiously. High speed is
generally preferred over low speed in combat situations. Properly flown, the
Fowler flaps of the P-38 allowed very tight turning radius."
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Standond, as far as I can tell you are asking if the flaps on the 38 work like the ones on the 51. The answer is yes but only at 250. I believe the 51's flaps work at a higher speed. There were no "speed flaps" on either plane that I know of. Just the regular flaps which activate at different speeds. On many of the American planes you can activate flaps to enhance manuevering.
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Ok, here is a simple explanation on the flap differences on American Planes. 1st off, there are 4 main types of flaps:
1. Plain Flaps
2. Split Flaps
3. Slotted Flaps
4. Fowler Flaps
See attached photo:
ANyways, briefly put,
The Plain Flaps are simply a hinged section of the trailing edge setup to hinge down. This includes the top section of the trailing edge as well. Aircraft with Plain Flaps include the F4u, P-51D, and.
The Split Flaps are setup exactly as they sound, they split away from the upper wing surface, leaving it intact, and hinge downwards. Neither the Spliut or the Plain Flap allow the airflow from the lower wing to go through the flap gap and over the top of the flap. A good example of an aircraft with a split flap being an F-6F, Wildcat, B-17, and AT-6.
Slotted Flaps are a variation of the plain flaps, the difference being that slotted flaps when extended allow a "Slot" to form between the Leading Edge of the Flap and the Trailing Edge of the Wing. The "slot" allows airflow to pass through from underneath the wing and exit over the top of the flap thereby lowering the pressure on top of the flap and increasing it's lift potential. Aircraft with Slotted flaps include the BT-13, Stearman, and BF-109.
Lastly we come to the Fowler Flap, the most effiecient flap design. A Fowler Flap is most distinguishable by it's ability to actually extend the trailing edge of the aircraft it is so attached to. This thereby increases the amount of wing area available for lift, and consequently with the slot formed by the lowering of the flap, increases potential lift. Good examples of fowler type flaps include the P-38, B-25, and A-26.
This is the best explanation that I have of the 4 main flap systems in play today. If you want to read more, there is an excellent article which I took the pic from of flaps on SimHQ.
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Excellent explanation Bodhi, job well done!