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View Full Version : Why did so few planes have divebrakes?



Frankthetank36
10-28-2009, 09:08 PM
The only fighters I can think of off the top of my head that had them are the P-38 (and only the later models) and the Corsair. But there are so many other planes that seem like they need them. I've been trying to practice with the Fw-190 but time and time again I find myself building up way too much speed in my dives when I spot enemies directly underneath, shooting by and unable to slow down, this thing would've been amazing with airbrakes.

Frankthetank36
10-28-2009, 09:08 PM
The only fighters I can think of off the top of my head that had them are the P-38 (and only the later models) and the Corsair. But there are so many other planes that seem like they need them. I've been trying to practice with the Fw-190 but time and time again I find myself building up way too much speed in my dives when I spot enemies directly underneath, shooting by and unable to slow down, this thing would've been amazing with airbrakes.

doraemil
10-28-2009, 10:18 PM
I just adjust during the dive or pull up to horizontal, wait a sec to bleed off speed, and split S . Granted if you're trying to go for surprise this might not work.

Ususally I cut throttle and set PP to 0 , that works good enough.

It's funny the Corsair's brakes are deploying its gear! I was laughing at that. Pretty ghetto but it works.

You can use full flaps and deploy gear, but I think they break around 400 km / hr (exception is combat flaps) but for me that's too slow to pull them back up and its easier to use a maneuver to control your speed.



IT's . .

partly the compressibility stall was a new discovery and most planes didn't dive bomb (near / vertically around 60 degrees to 90) that much . . .

They didn't need air brakes because they didn't have the speeds like jet fighters would later (and air brakes would help in overshooting which is kind of important for dogfighting).


Most fighters when they needed to dive, required all the speed they needed.

And that's something extra you have to put in, which adds to weight / one more thing maintenance has to check . . . and that for non dive bombers the advantages aren't enough to justify.

For something like the P-38, pilot safety was a concern and since high speed compressibility stall was a known issue with that plane, Lockheed decided it put them in.

Waldo.Pepper
10-28-2009, 10:27 PM
http://www.internationalhero.co.uk/s/sphinx.jpg

Turn your question on its head and you will have the majority of the answer. Ask yourself - "Why should all planes have dive brakes?"

ImpStarDuece
10-28-2009, 11:42 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Frankthetank36:
The only fighters I can think of off the top of my head that had them are the P-38 (and only the later models) and the Corsair. But there are so many other planes that seem like they need them. I've been trying to practice with the Fw-190 but time and time again I find myself building up way too much speed in my dives when I spot enemies directly underneath, shooting by and unable to slow down, this thing would've been amazing with airbrakes. </div></BLOCKQUOTE>

I believe some of the late model P-47s (the M and N) had dive brakes as well. Perhaps also some of the very late production D blocks had them as well.

Most fighters didn't have them because, frankly, they didn't need them.

There are also other considerations to think of, such as the fact that high-speed compressibility was not really understood at the time, nor were phenomena like mach-tuck, so there was no perceived need for them.

Ba5tard5word
10-29-2009, 12:19 AM
Lower throttle, lower prop pitch, do maneuvers to bleed speed, etc.

Unknown-Pilot
10-29-2009, 07:28 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ba5tard5word:
Lower throttle, lower prop pitch, do maneuvers to bleed speed, etc. </div></BLOCKQUOTE>

I've always found a lower pitch to increase speed, not decrease it. And in a way it makes sense...even though I can't put it into words very well. lol

Outlaw---
10-29-2009, 08:15 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Unknown-Pilot:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Ba5tard5word:
Lower throttle, lower prop pitch, do maneuvers to bleed speed, etc. </div></BLOCKQUOTE>

I've always found a lower pitch to increase speed, not decrease it. And in a way it makes sense...even though I can't put it into words very well. lol </div></BLOCKQUOTE>

It depends on the definition of "high" and "low" and the type of "pitch" control you're using. Constant speed props govern the RPM, not the prop pitch directly. Setting it to "high" RPM will present the "flat" of the blade to the wind. This moves less air when the engine is turning the prop thus allowing the engine to turn faster and, thus, develop more horsepower. When the preset max engine RPM allowed by the governor is reached the pitch increases to prevent over-rev. Conversely, this provides the most drag when the airspeed is faster than what the engine can produce. So, to limit dive speed drop power to idle and select "high RPM" on the prop governor.

If your aircraft has a direct pitch control, then set it to low pitch for max drag in power off situations (such as when diving).

--Outlaw.

tomco1965
10-29-2009, 09:13 AM
This reminds me of the time my wife came home, walked into the livingroom and asked "why are the curtains closed?". I told her, "because nobody opened them?".

K_Freddie
10-29-2009, 09:28 AM
DON'T EVER... mention dive brakes.... you'll throw the 'energy fighters' into a spin
http://forums.ubi.com/images/smilies/16x16_smiley-very-happy.gif

Crash_Moses
10-29-2009, 10:44 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ImpStarDuece:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Frankthetank36:
The only fighters I can think of off the top of my head that had them are the P-38 (and only the later models) and the Corsair. But there are so many other planes that seem like they need them. I've been trying to practice with the Fw-190 but time and time again I find myself building up way too much speed in my dives when I spot enemies directly underneath, shooting by and unable to slow down, this thing would've been amazing with airbrakes. </div></BLOCKQUOTE>

I believe some of the late model P-47s (the M and N) had dive brakes as well. Perhaps also some of the very late production D blocks had them as well.

Most fighters didn't have them because, frankly, they didn't need them.

There are also other considerations to think of, such as the fact that high-speed compressibility was not really understood at the time, nor were phenomena like mach-tuck, so there was no perceived need for them. </div></BLOCKQUOTE>

Correct. In fact, the main reason dive brakes were installed on the P-38 was the problems with compressibility...something early war fighters didn't have to deal with too much. And it wasn't until later in the war that engine and airframe technology allowed for the manufacture of real weapons platforms such as the Corsair. Can you imagine diving in a TBD? Zoiks!

Of course, the SBD had them all along and as you know...it won the war. Twice.

Daiichidoku
10-29-2009, 01:21 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by ImpStarDuece:
I believe some of the late model P-47s (the M and N) had dive brakes as well. Perhaps also some of the very late production D blocks had them as well. </div></BLOCKQUOTE>

D-30 block onwards had em installed

also installed on Bearcats, P80s, P59s, and most interestingly, A/B26 Invaders

they were also tested on Hellcats and Mustangs

Frankthetank36
10-29-2009, 04:22 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by doraemil:


It's funny the Corsair's brakes are deploying its gear! I was laughing at that. Pretty ghetto but it works.

</div></BLOCKQUOTE>

Eh? Haven't used the Corsair in IL2 enough to know that but in MCFS2 it had real spoilers.

RPMcMurphy
10-29-2009, 04:47 PM
Open your canopy and then stick your middle finger out at the enemy.
Flip him the bird. This may cause some drag to slow you down a little.

NZ_Tui
10-30-2009, 02:13 AM
Hmmm I believe the very early P-51's had dive brakes but where not wired up to work....is this true?

PanzerAce
10-30-2009, 03:36 AM
the A-36s did have dive brakes. Not sure about the -51As...

Kettenhunde
10-30-2009, 04:33 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why did so few planes have divebrakes?
</div></BLOCKQUOTE>

The airfoil chosen has the most influence on the need for divebrakes.

BillSwagger
10-30-2009, 05:00 AM
To add to that, on some planes they were called dive flaps which aided in getting the nose of the plane up. I'm sure they also slowed the plane up some in the process.
From what i've read they weren't really used that way, but were very capable.
It was a normal part of dive procedure to deploy the dive flaps prior to the dive on some craft like the P-38 and P-47.
My guess is that this insured that the plane would not over speed or become uncontrollable when the pilot is also trying to point his nose at the target to bomb.

I'm sure deploying the dive flaps in mid dive also caused a sudden shift in pitch which would make accuracy a bit tough if you didn't have time to adjust or make corrections.

julian265
10-30-2009, 06:10 AM
Re pitch - leave it at the 100% setting (or max safe rpm when in direct mode of a 109) for maximum deceleration, without exceptions.

Making the prop more streamlined (ie coarser aka lower % pitch) and letting the engine be turned over slower only lowers your drag.

julian265
10-30-2009, 06:20 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Kettenhunde:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> Why did so few planes have divebrakes?
</div></BLOCKQUOTE>

The airfoil chosen has the most influence on the need for divebrakes. </div></BLOCKQUOTE>

"Why is the sky blue?"
"Light waves and gas molecules have the most influence on our sky's colour"

Frankthetank36
10-30-2009, 08:55 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by BillSwagger:
To add to that, on some planes they were called dive flaps which aided in getting the nose of the plane up. I'm sure they also slowed the plane up some in the process.
From what i've read they weren't really used that way, but were very capable.
It was a normal part of dive procedure to deploy the dive flaps prior to the dive on some craft like the P-38 and P-47.
My guess is that this insured that the plane would not over speed or become uncontrollable when the pilot is also trying to point his nose at the target to bomb.

I'm sure deploying the dive flaps in mid dive also caused a sudden shift in pitch which would make accuracy a bit tough if you didn't have time to adjust or make corrections. </div></BLOCKQUOTE>

Well look at the P-80, it has airbrakes on the nose, nowhere near the wings, and modern fighters often fold both rudders inward to slow down (or they split the rudder it it only has one tail fin). I'm sure if they just made brakes that consisted of flaps on the left and right sides of the fuselage it would not change the pitch at all.

Another reason for adding airbrakes: if you have them and the bandit on your tail doesn't, you can force an overshoot much more quickly than by slipping and using zero power with cowl flaps. The problem with using wing flaps and gear for this is that they break over a certain speed, and gear takes a LONG time to deploy.

Daiichidoku
10-30-2009, 09:11 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Frankthetank36:
Well look at the P-80, it has airbrakes on the nose, nowhere near the wings </div></BLOCKQUOTE>

http://www.hq.nasa.gov/pao/History/SP-468/ch11-2.htm

http://img.photobucket.com/albums/v479/Daiichidoku/p287.jpg

Frankthetank36
10-30-2009, 12:04 PM
I stand corrected, but they still are not actually on the wings. And I still don't see why they didn't just add flaps on the fuselage sides.

AndyJWest
10-30-2009, 12:10 PM
Fuselage-mounted dive brakes will disrupt the airflow behind when opened - putting them in the belly looks a sensible choice. There are also structural and weight factors to take into consideration.

TS_Sancho
10-30-2009, 01:27 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Another reason for adding airbrakes: if you have them and the bandit on your tail doesn't, you can force an overshoot much more quickly than by slipping and using zero power with cowl flaps. </div></BLOCKQUOTE>

That only works in F14's when being chased by F5's and A4's.

"I'm gonna hit the brakes Goose, he'll fly right by." http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif

Sillius_Sodus
10-30-2009, 01:48 PM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by TS_Sancho:
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Another reason for adding airbrakes: if you have them and the bandit on your tail doesn't, you can force an overshoot much more quickly than by slipping and using zero power with cowl flaps. </div></BLOCKQUOTE>

That only works in F14's when being chased by F5's and A4's.

"I'm gonna hit the brakes Goose, he'll fly right by." http://forums.ubi.com/groupee_common/emoticons/icon_smile.gif </div></BLOCKQUOTE>

Yes, and only if you firewall the throttles and pull back on the stick http://forums.ubi.com/images/smilies/88.gif

horseback
11-01-2009, 09:57 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by NZ_Tui:
Hmmm I believe the very early P-51's had dive brakes but where not wired up to work....is this true? </div></BLOCKQUOTE>The dive bomber version of the Mustang, the A-36 Apache, had dive brakes, but many of them did eventually have them wired closed because divebombing was simply not that effective at that point in the war. It was usually better to convert the energy gathered in a dive into speed so as to get the heck away from all that ground fire...

The main point of dive brakes in a dive bomber is to provide the pilot with more time and control to aim accurately. The purpose of dive brakes in a fighter is to slow down before important pieces of your airplane start coming off at an inconvenient time.

As a side note, the contract for the A-36 was placed primarily to keep the Mustang line in production until the Congress authorized more funding for new fighters in early 1942; apparently, there was still some money left in the Army's purse designated for ground attack so they could use that. The A-36 turned out to be quite effective in its intended role, but by the time they figured that out, the production line had moved on to churn out P-51As and then in late 1942, several people on both sides of the Atlantic got the bright idea of putting a Merlin in it...

cheers

horseback

Kettenhunde
11-01-2009, 11:42 AM
<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> many of them did eventually have them wired closed </div></BLOCKQUOTE>

Hi Horseback,

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content"> A sort of urban legend has sprung up about the A-36A's dive brakes. According to some stories, the dive brakes of the A-36A were next to useless and were deliberately wired shut at the manufacturers so that they could not be used. This story is totally incorrect. On the contrary, the dive brakes proved to be quite effective in combat, and the aircraft was so stable with the dive brakes extended that bombing while in a dive was particularly accurate. The origin of this legend seems to have been in the United States, at a time before the A-36s first went overseas. It seems that A-36A pilots were told by their officers in the USA that their dive brakes would be all but useless in combat and it would be best if they simply wired them shut. This turned out to be incorrect, and the dive brakes were used to great effect throughout the Sicilian campaign and the Italian invasion.

</div></BLOCKQUOTE>

http://home.att.net/~jbaugher1/p51_6.html (http://home.att.net/%7Ejbaugher1/p51_6.html)

Wiring them shut does not make any sense at all. It does not fit into the aerodynamics or the tightly controlled way in which all airplanes are maintained.

It smacks of the same uninformed speculation that gave rise to the "wiring the Bf-109's slats shut" myths.

All the best,

Crumpp