P38 Performance

[Drano]

It isn't really at a right angle to the airflow. More like 40-45 degrees. Check this video at about 2:50:

http://www.youtube.com/watch?v=Y3nddCJbcdI&list=PL2hjKZefRkH82sWPVrLHcpeFt0lkYkCrU

Jeff Ethell gives an explanation of it and you'll see it operate on the ground. Sadly he wrecked this bird and was killed not long after this was made.

[GScholz]

Another bug then. Take a look at them in the game. (Or just see the bottom picture I posted).

[Drano]

Graphics thing. Doesn't bother me. I can't see it from the cockpit. If they wanted to fix it that's great but it's no biggy. It seems to work as it should tho and that's all I care.

[Mongoose]

Another bug then. Take a look at them in the game. (Or just see the bottom picture I posted).

So the bug, then, is in the graphic, not the affect on the flight characteristics.

[GScholz]

You cannot have a flap protruding from the wing like that, at any angle, and not have it create drag. It is simply impossible. Hell, something as small and aerodynamic as a bomb rack or droptank pylon reduces top speed by several mph.

[Ack-Ack]

Another bug then. Take a look at them in the game. (Or just see the bottom picture I posted).

It's a graphic bug with the P-38, not how the dive flaps looked in real life.  Here is another shot of the dive flaps in AH.


This is what the design of the dive flaps looked like.


Dive flaps deployed.








ack-ack

[Randy1]

Mach Tuck. 

Here are some good articles.

http://en.wikipedia.org/wiki/Mach_tuck

http://www.airspacemag.com/history-of-flight/mach-1-assaulting-the-barrier-22647052/

[Drano]

You cannot have a flap protruding from the wing like that, at any angle, and not have it create drag. It is simply impossible. Hell, something as small and aerodynamic as a bomb rack or droptank pylon reduces top speed by several mph.

Believe me when I say I totally hear what you're saying about the drag but what I'm trying to get at is what you really want. Are you saying you want this flap to act like a standard dive flap, as in like a dive flap on a dive bomber would? Because it sure does sound like that. Again--these are not speed brakes. It's not a game glitch. They weren't designed as such in RL.

If they did slow the RL plane down I'd be interested in seeing some data to that effect. I'd imagine whatever effect on speed (and yes it makes sense to me that as it's protruding into the windstream and I'd think it should have SOME effect) would be minmal at best if only becasue of the size, angle and location of the flap. It was engineered to death and I'm sure that's the reason it's the size it is and is at the angle it is and it's where it is--to do a specific job. It's not very large and it protrudes at a shallow angle to the windstream quite unlike a standard dive brake which is larger and extends to almost perpendicular to the windstream.

[GScholz]

I don't want it to behave in any other what than what it did in real life. It is not a dive brake. It is a dive flap; A device that counteracts the Mach-tuck effect of a wing with different curvature on the upper and lower wing surface. However it counteracts this force by deflecting air downward. That must produce drag, and significant amounts of it. Not like an air brake that would almost stop the plane from flying in level flight, but it should significantly affect top level speed, like in the order of several tens of mph.

[Banshee7]

I solved the whole issue by flying the G and J models 

[GScholz]

 

[Randy1]

Any alteration of the skin effects the drag coefficient.  The question is by how much.  Without a test or calculation the argument is mute. 

[BuckShot]

Whether it was the intent out not, if it protrudes into the airstream it creates drag and slows down the plane.

Gscholz is correct about that.

Drano is correct about their intended purpose.

AH is incorrect in that the 38's speed is unaffected by them being deployed in level flight. It is physically impossible to throw something like that into the airstream and have it not affect speed at a static power setting. Physics is a B-atch like that.

~S~ Buck

[GScholz]

Like I wrote in the bug thread all the info needed is actually in that pilot's handbook that was quoted earlier in this thread.

Note that the flaps do not allow for an increase in dive speed of more than "15 or 20 mph" while allowing an increase in dive angle of 30 degrees (from 15 degrees without flaps to 45 degrees with flaps). That takes drag... and a lot of it.

Not 90 degree dive bomber speed brake drag of course, but 45 degree dive bomber speed brake drag...

With the dive flaps extended the P-38L should be able to safely dive at 45 degrees, but the top dive speed should only be 15 to 20 mph more than in a 15 degree dive without dive flaps.

[Badboy]

I don't want it to behave in any other what than what it did in real life.

In that, I am sure we all agree.

I am also sure nobody wants that more than HTC.

but it should significantly affect top level speed, like in the order of several tens of mph.

The problem is that intuitive estimates like that are meaningless without some form of data to support it. At best I think any data that could be found would be in the form of modified drag polars because I'm sure there would have at least been wind tunnel tests involved in that type of modification. It is very unlikely that anyone actually conducted tests for top speed with the dive recovery flaps deployed, so data for direct values probably does not exist. So even if data can be found it would probably require some analysis to interpret. I know that HTC can do the analysis, so if the data exists and can be found, I'm sure they would incorporate it if they haven't already done so.

Without any real data, all any of us can do is little more than speculation.

Badboy