P-39q vs. Cannon

[Slade]

For you P-39q die hards, where do you like to set your convergence on the cannon?

Does it fly better once all the 50 cals used up?  I was thinking the role-rate would be better in this case.


I am trying to learn this bird better. Thanks! 

[glzsqd]

Don't fly it with gondies

[Oldman731]

Don't fly it with gondies

Agreed. 

I set the cannon and the nose .50s at 300 yards.

- oldman

[Slade]

Thanks for the feedback.

Concerning the convergence of 300 and the cannon...

If you are flying level and dead on his 6 at 300 out: do you aim\fire on where the cross-hairs indicate or do you aim\fire slightly above or below the cross-hairs?


Thanks again. 

[ink]

Thanks for the feedback.

Concerning the convergence of 300...

If you are flying level and dead on his 6 at 300 out: do you aim\fire on where the cross-hairs indicate or do you aim\fire slightly above the cross-hairs?


Thanks again. 

dead 6 at convergence...should be right on the pipper.....IIRC

now on a side note...the dead 6 shot is the hardest to make....you should be trying for an angle where you can rake the plane...

[PJ_Godzilla]

This will be the stupid question of the day. I've got my asbestos underwear on. Hit me, I'm open.

BUT...

I always wondered why we set convergence on a center line cannon. Your statement implies that the convergence distance is also the drop zero. Is that correct?

[Skyyr]

I always wondered why we set convergence on a center line cannon. Your statement implies that the convergence distance is also the drop zero. Is that correct?

Convergence is where point of aim equals point of impact.

[PJ_Godzilla]

Convergence is where point of aim equals point of impact.

You answered my question. Thanks.

For some strange reason, I discounted vertical convergence in my thinking.

[Skyyr]

You answered my question. Thanks.

For some strange reason, I discounted vertical convergence in my thinking.

NP. Some games model horizontal and vertical convergence separately (such as some of the IL2 series).

[bustr]

Hitech has kindly allowed us to elevate the barrel of the motor mounted cannon up out of the center line of the motor. There is no "zero" choice in the convergence hanger, only 125. It's his game and he has never explained why in the years I've been here. You learn to respect his decisions or have really good data to not waste his time with.

In the real world all motor mounted cannon were bolted inline with the prop center line. Then as soon as the round left the barrel it started dropping. The only thing elevating a center line gun does is confuse you about your IP point. By 400 for that single cannon, dispersion is becoming your enemy even if you set the convergence to 400. 300 and closer you will have issues with aiming too high especially on 6 shots. With 109 and Yak, often you will be hitting the con with your hood MG thinking you are nailing it with your cannon anyway.

Here is a link to my last effort at wish listing motor cannon locked to the engine zero line. You will see how the MK151/20 and MK108 were locked to the DB605 to insure the rounds passed through the shot tube and out the center of the prop HUB. And how the same was accomplished with the Yaks and P39.

 http://bbs.hitechcreations.com/smf/index.php/topic,362504.msg4820407.html#msg4820407

[PJ_Godzilla]

Thanks, Bustr. That's solid background. It also lends some context to why I was confused. I've actually looked at drawings of the 109s motorkanone. I get your comment, though the barrel is locked to a line parallel to the crank axis, but offset -which I know you get, though I feel duty bound to clarify for anyone who does not. Geared hub and all...

Through all this, skyyr's a good sort, though I can see why people get sick of bnZers. I had to chase Titan down in his pony the other weekend for revenge. He put up a good fight but, as we know, k4 has all the advantages in that fight. Titan's a good guy and deserves a salute -and I owed him one... Best pony fight I've had.

[bustr]

The shot tube "panzerrohr" is also referred to as the "mittelbohrung" or central bore. Even with the F6f or Spit XIV, the engine was mounted with a down tilt and not a tilted anything internally. The center line of the merlin, griffin, Dailmer-Benz or Junkers is through the central bore that the prop spins on.

[PJ_Godzilla]

The shot tube "panzerrohr" is also referred to as the "mittelbohrung" or central bore. Even with the F6f or Spit XIV, the engine was mounted with a down tilt and not a tilted anything internally. The center line of the merlin, griffin, Dailmer-Benz or Junkers is through the central bore that the prop spins on.

Meaning the center line of the DB is the Cl of the output shaft, not the Cl of the crank.

With the Merlin, I'd expect the Cl of the crank to coincide with the Cl of the prop hub.

[bustr]

You are splitting hairs because I responded to you.....

[icepac]

The reason you set convergence on a centerline weapon is that the aces high convergence adjustment range also impacts the vertical axis.

I completely ignore the horizontal effects of convergence and concentrate on making sure I don't have bullets wasted going over or under an enemy plane.

For wing guns, I don't like short convergence since I often like to shoot at extreme distances to force a running con to start turning.

Having them cross at 300 means I might not land any shots on a plane at 900 but rather shoot on either side while long convergence never has that problem.