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General Forums => Aces High General Discussion => Topic started by: UnDeth on July 12, 2002, 02:50:29 PM

Title: Dive Breaks?
Post by: UnDeth on July 12, 2002, 02:50:29 PM

Does anyone know if Dive breaks work?  I've tested them on several planes and I can't see any effect.

UnDeth

Title: Dive Breaks?
Post by: Kevin14 on July 12, 2002, 03:00:31 PM

I was flying a P38 with my buddy one time, same alt, same speed, he went into a steep dive and near the end he pulled out while I went screaming into the ground. So yes, they do increase the speed needed for compression

Title: Dive Breaks?
Post by: Majors on July 12, 2002, 03:07:16 PM

Hi Mates

Have extended the dive brakes on the SBD but they don't seem to slow it down that much in a dive.  Looks good but not sure they work that well.

Majors
249RAF
Oldest Yank in the RAF

Title: Dive Breaks?
Post by: Animal on July 12, 2002, 03:10:26 PM

Dive brakes are not for slowing down, but for helping the plane come out of a compression. They somewhat work on the P-38L.

Title: Dive Breaks?
Post by: Widewing on July 12, 2002, 03:25:48 PM

Quote

Originally posted by Animal
Dive brakes are not for slowing down, but for helping the plane come out of a compression. They somewhat work on the P-38L.

In the real world, "dive recovery flaps" did several things.

1) Increased drag. Essentially, they decreased the acceleration rate, and reduced terminal velocity.

2) Shifted the center of lift forward along the chord of the wing, greatly reducing the much dreaded "Mach tuck".

In respect to the P-38, if the dive recovery flaps were deployed before or in the early stages of a dive, a neutral trimmed P-38 would execute a 3G, hands-off pullout.

Grumman would also join the dive recovery flat parade by installing them on the F8F-1 Bearcat.

My regards,

Widewing

Title: Dive Breaks?
Post by: Animal on July 12, 2002, 03:31:59 PM

oops

Title: Dive Breaks?
Post by: JoeDirt on July 12, 2002, 04:04:31 PM

oops is right you fat drunk bastard!

Title: Dive Breaks?
Post by: akak on July 12, 2002, 04:07:54 PM

Quote

Originally posted by Widewing


In the real world, "dive recovery flaps" did several things.

1) Increased drag. Essentially, they decreased the acceleration rate, and reduced terminal velocity.



My regards,

Widewing

The dive flaps on the P-38L didn't increase drag like normal flaps but instead redirected the airflow over the surface wing to increase lift to help counter the compressibility problem.

[Source...Compressibility (http://www.p-38online.com/cmprs.html)]


(http://www.hispanicvista.com/assets/479th_shield.jpg)
Ack-Ack
479th Fighter Group - Riddle's Raiders

Title: Dive Breaks?
Post by: Steven on July 12, 2002, 05:57:00 PM

Dive brakes on the SBD work.  However, you have to chop throttle to nothing or you are defeating the purpose.

Title: Dive Breaks?
Post by: Kweassa on July 12, 2002, 06:32:31 PM

With dive flaps engaged on the SBD, a dive bomb run from 12k to 6k (6k drop) with throttle set to minimum increases speed by about 100mph. I'd begin the the dive at about 200mph, and the speed rarely goes up higher than 350mph. I'd say the dive break works pretty well.

ps) SBD is a very reliable anti-ship dive bomber. I survived every run I ever tried in the SBD with good results. Only weakness is the payload is very limited, so you are gonna need a lot of people in dive bombers to knock out a CV..

Title: Dive Breaks?
Post by: akak on July 12, 2002, 07:01:00 PM

Quote

Originally posted by Kweassa
so you are gonna need a lot of people in dive bombers to knock out a CV..

And just how it should be....



Ack-Ack

Title: Dive Breaks?
Post by: SKurj on July 13, 2002, 12:50:28 AM

Supposedly an SBD would hold a speed around 280mph with brakes dropped on a dive 'by the books'  I am guessing that is throttle closed.

Sweet plane.. now i just have to find the handle to open that canopy!


SKurj

Title: Dive Breaks?
Post by: SKurj on July 13, 2002, 12:54:01 AM

Just curious widewing as you seem to be one of the most knowledgeable...

What about an airbrake on the F6f?  I remember a model kit i built years ago had a panel i think it was behind the cockpit that raised?(been a long time could be in error).. and of course AW's F6 had a dive brake.

Also I have read about the practice of F6f pilots dropping their landing gear while divebombing as a dive brake.  The gear wouldn't lock at speeds over 130mph..

Any truth to the above?


SKurj

Title: Dive Breaks?
Post by: UnDeth on July 13, 2002, 01:56:37 AM

Thanks for the posts guys.  I'll work more with the P38 dive flaps and see how much it helps.  I've noticed if I extend the dive flaps after I'm compressing it doesn't help much.  I'll try extending prior to the dive and see if it helps.

UnDeth

Title: Dive Breaks?
Post by: akak on July 13, 2002, 02:16:51 AM

Quote

Originally posted by UnDeth
Thanks for the posts guys.  I'll work more with the P38 dive flaps and see how much it helps.  I've noticed if I extend the dive flaps after I'm compressing it doesn't help much.  I'll try extending prior to the dive and see if it helps.

UnDeth

In order to avoid compressibiliy in the P-38, don't start your dives above 20,000ft.  At least in the P-38, compression only happens at altitudes above that and not below 20,000ft.  Using your dive flaps before entering the dive will help and will be pretty useless after you've entered the dive.  In real life, one of the test P-38 planes had it's wings rip off when the test pilot decided to see what happens when he deployed the dive flaps in the middle of a dive.

One big misconception in here is that the dive flaps will help you in turn fights since it gives you about a 4 degrees nose up pitch.  It doesn't help in turn fights since the nose up pitch only comes when at high speeds with the dive flaps deployed.  The dive flaps aren't the same as the maneuvering flaps (i.e. Fowler Flaps, combat flaps) either.  The maneuvering flaps are the first setting of your flaps.  When you deploy the first notch of flaps, that lowers the flaps 8 degrees for maneuvering.

The photo below shows both the dive flaps and 'Foweler flaps" deployed.  

(http://www.kazoku.org/xp-38n/walkaround/dsc00726.jpg)





(http://www.hispanicvista.com/assets/479th_shield.jpg)
Ack-Ack
479th FG - Riddle's Raiders

Title: Dive Breaks?
Post by: Vermillion on July 13, 2002, 10:17:39 AM

Quote

so you are gonna need a lot of people in dive bombers to knock out a CV..

And just how it should be....

Well... According to "Striking Power of Airborne Weapons; based upon Bureau of Ships Study "Vulnerability of US Naval Vessels to Air Attack by Airborne Weapons" by Air Intelligence Group, Division of Naval Intelligence Office, July 1944.

Aircraft Carriers (CV's Less Ranger)

                                            Probability of Sinking for No. of Hits
[u]Weapon[/u]          [u]Charge Weight[/u]       [u]   1        2        3        4        5        6[/u]
Torpedo             660# TNT          0.06        0.12        0.50        0.90       0.95        0.99
1000#AP             125# TNT          0.23        0.41        0.55        0.70       0.90        0.99
1000#GP             500# TNT          0.03        0.10        0.20        0.30       0.50        0.80
2000#GP            1000# TNT          0.10        0.30        0.80        0.90       0.96        0.99

Title: Dive Breaks?
Post by: Grimm on July 13, 2002, 11:19:09 AM

Quote

Originally posted by akak

The photo below shows both the dive flaps and 'Foweler flaps" deployed.  

(http://www.kazoku.org/xp-38n/walkaround/dsc00726.jpg)

This looks like the Marge Replica, P-38 sitting in the Eagle Hanger at the EAA Museum in Oshkosh WI.    :)    

Am I right ;)

Title: Dive Breaks?
Post by: akak on July 13, 2002, 05:59:56 PM

Quote

Originally posted by Grimm


This looks like the Marge Replica, P-38 sitting in the Eagle Hanger at the EAA Museum in Oshkosh WI.    :)    

Am I right ;)

Yep, it's a replica of Bong's Marge P-38J.  The pictured P-38 is actually a P-38L painted to look like a P-38J.

Title: Dive Breaks?
Post by: Grimm on July 13, 2002, 06:52:55 PM

heheehehe   I  knew that ;)

10 days till Im off  to Oshkosh.

Title: Dive Breaks?
Post by: Captain Virgil Hilts on July 14, 2002, 12:41:09 PM

Quote

Originally posted by akak


In order to avoid compressibiliy in the P-38, don't start your dives above 20,000ft.  At least in the P-38, compression only happens at altitudes above that and not below 20,000ft.  Using your dive flaps before entering the dive will help and will be pretty useless after you've entered the dive.  In real life, one of the test P-38 planes had it's wings rip off when the test pilot decided to see what happens when he deployed the dive flaps in the middle of a dive.

One big misconception in here is that the dive flaps will help you in turn fights since it gives you about a 4 degrees nose up pitch.  It doesn't help in turn fights since the nose up pitch only comes when at high speeds with the dive flaps deployed.  The dive flaps aren't the same as the maneuvering flaps (i.e. Fowler Flaps, combat flaps) either.  The maneuvering flaps are the first setting of your flaps.  When you deploy the first notch of flaps, that lowers the flaps 8 degrees for maneuvering.

The photo below shows both the dive flaps and 'Foweler flaps" deployed.  

(http://www.kazoku.org/xp-38n/walkaround/dsc00726.jpg)





(http://www.hispanicvista.com/assets/479th_shield.jpg)
Ack-Ack
479th FG - Riddle's Raiders

That picture is wierd. It makes the dive flap appear to be nothing more than a single sheet of aluminum on a hinge, rather than two pieces hinged to form a "Vee" when deployed. I looked at that picture several times over a period of half an hour or so and it never looked right. I pulled out a tape of Jeff Ethell flying the P-38 and it showed the flap from neutral to deployed and back to neutral, and I was wrong, that is indeed the dive flap, it just didn't look right.

While it may not work in AH, the dive flap SHOULD cause a momentary nose up when deployed in a fight. Several pilots, including Art Heiden, Stan Richardson, and Jack Ilfrey, said they used them to get shots that way. When they needed that little bit of nose up to get the shot, they simply dropped the "speed boards" for a few seconds.

As far as their use as dive flaps to reduce buffeting and aid recovery from compressibility in AH, they don't seem to have much effect. But then the Fowlers don't work quite right either, and they should not auto retract, period. Much has been made of the fact there are several "notches" of flap on the P-38 in AH and there should be only three. The problem is, there were only three DETENTS on the flap leversof most P-38s, but there was a large range of flap setting adjustment that was NOT set to a detent. In other words, you could set the flaps in places other than the detents. However, this would be difficult to model in a sim, especially a combat sim, since there would be too much information to display and too little time to evaluate it. A seperate control and indicator could be added so that you could either set them to a detent, or adjust them much like you adjust trim on an elevator or aileron.

Title: Dive Breaks?
Post by: Innominate on July 14, 2002, 12:55:08 PM

Quote

Originally posted by SKurj

Also I have read about the practice of F6f pilots dropping their landing gear while divebombing as a dive brake.  The gear wouldn't lock at speeds over 130mph..

I duno about the f6f, but the f4u had a dive brake setting for it's gear, to put them part of the way down and act as a dive brake.  In AH, you can drop the f4u's gear all the way up to 400mph.

Title: Dive Breaks?
Post by: akak on July 14, 2002, 02:25:40 PM

Quote

Originally posted by Captain Virgil Hilts



While it may not work in AH, the dive flap SHOULD cause a momentary nose up when deployed in a fight. Several pilots, including Art Heiden, Stan Richardson, and Jack Ilfrey, said they used them to get shots that way. When they needed that little bit of nose up to get the shot, they simply dropped the "speed boards" for a few seconds.

They do work in AH but have to be pretty much above 300mph to get the nose to pull up when the dive flaps are deployed.  

Interesting thing on the flaps, here's an illustration I found of the P-38 flaps, from the F model on forwards.






(http://www.kazoku.org/xp-38n/articles/p38flapsystem.gif)
It shows the three flap positions in addition to the Fowler Flap setting.  




(http://www.hispanicvista.com/assets/479th_shield.jpg)
Ack-Ack
479th FG - Riddle's Raiders

Title: Dive Breaks?
Post by: Captain Virgil Hilts on July 14, 2002, 02:49:48 PM

Quote

Originally posted by akak


They do work in AH but have to be pretty much above 300mph to get the nose to pull up when the dive flaps are deployed.  

Interesting thing on the flaps, here's an illustration I found of the P-38 flaps, from the F model on forwards.






(http://www.kazoku.org/xp-38n/articles/p38flapsystem.gif)
It shows the three flap positions in addition to the Fowler Flap setting.  




(http://www.hispanicvista.com/assets/479th_shield.jpg)
Ack-Ack
479th FG - Riddle's Raiders

That would show a total of four detents besides the up or closed position, which seems to agree with several other sources. Many pilots report using settings between the detents.

As far as the use of dive flaps to pitch the nose up, I'm not sure what speed those guys were talking about. One thing, most of those guys didn't fly the way we do, getting way down around 200 MPH or so. That's not the way to survive, if your life REALLY depends on it. Figure that if they entered combat at around 350-390 MPH, they made maybe one or two real turns, and then got the hell out of Dodge. One thing most people don't realize is that piston engine prop planes can only make one or two real turns before they hit the 200 MPH zone, and that's if they were at 350+ and diving in to begin with. Even FAST accelerating planes like the Me 109 and the P-38 don't accelerate like more modern jets do. Sure, the guy you are fighting is getting as slow as you are pretty quickly. But that doesn't mean everyone else around you is. Turnfighting is easy to do here, since when you die, you wake up in a tower ready to go again.