P-51D vs P-51B Directional Stability

[SectorNine50]

I did some poking around and didn't seem to find quite what I was looking for.

I seem to recall that the razorback on the P-51B made it so that it had more directional stability than the Delta model.  However, the D model was later given the extension on the front of the vertical stab to help aid this problem.

Now from personal experience in-game, the Delta is way more stable than the Bravo, and I'm curious as to why that would be.  It's actually fairly surprising to me how different the two birds fly from each other, particularly considering they are basically the same airframe.  Logic tells me that that the bubble canopy, even with the addition to the vertical stab, should make a less directionally stable aircraft than the razorback on the Bravo.  However, the Delta seems to be quite a bit more stable.

Any thoughts on this?

[Strip]

The Delta is way more stable than the B?

 

Strip

[SectorNine50]

Directionally, yes.  At least it seems that way.  I don't seem to be playing with the rudder to keep the Delta coordinated nearly as much as the Bravo.  Do you have a different experience?

[321BAR]

Directionally, yes.  At least it seems that way.  I don't seem to be playing with the rudder to keep the Delta coordinated nearly as much as the Bravo.  Do you have a different experience?

both seem stable but the B is more stable than the D in my mind also. prob why i like it more...

[SectorNine50]

both seem stable but the B is more stable than the D in my mind also. prob why i like it more...

I'm surprised you say that, as the Pony's are some of the most directionally unstable aircraft in the game, if not the game than at least the most unstable American aircraft.  The P-47's, P-38's and F4U's require next to no rudder input to stay coordinated compared to the P-51.

I swear though, the D seems to fly more like a Cadillac than the B.  The Bravo is definitely more maneuverable and sporty, and it is also my preference to fly, but just was wondering if anyone else had the same experiences.  So far doesn't seem to be the case.

[JOACH1M]

The longer nose of d model makes it slightly heavier and more unstable then B


The d weighs more too.

[MiloMorai]

The longer nose of d model makes it slightly heavier and more unstable then B

Agh?

[SectorNine50]

The longer nose of d model makes it slightly heavier and more unstable then B


The d weighs more too.

I'm not sure what you mean by the longer nose, both aircraft are 32ft and 3.5" long, unless your saying the cockpit was moved back on the Delta, but I don't think that's the case.  I can't think of a reason they'd need to, both have basically the same engines in them.

The extra 600lbs or so might be the reason I get more of a "Cadillac" feeling though.

[Jabberwock]

The longer nose of d model makes it slightly heavier and more unstable then B


The d weighs more too.

Gaston... is that you?

 

[321BAR]

I'm not sure what you mean by the longer nose, both aircraft are 32ft and 3.5" long, unless your saying the cockpit was moved back on the Delta, but I don't think that's the case.  I can't think of a reason they'd need to, both have basically the same engines in them.

The extra 600lbs or so might be the reason I get more of a "Cadillac" feeling though.

honestly the 51s seem stable to me. i know not as stable as a 38 or something of the sorts. When im in a 51 i let it do the flying not me though...

[SIK1]

Gaston... is that you?

 

 

[MiloMorai]

Gaston... is that you?

 

Naw, he has found a new board for the gibberish he spews from his soapbox.

[JOACH1M]

Naw, he has found a new board for the gibberish he spews from his soapbox.

[drgondog]

There is no difference in length between the B and D. The ventral fin was added to the P-51D-5 because NAA engineers thought it would improve directional stability and the NAA engineers experimented with a taller vertical stabilizer that did help but it wasn't installed until the P-51H.  It was later determined that the removal of the 'turtleback' to accomodate the teardrop canopy was not the major factor in the very slight difference in yaw stability - that the increase in Hp was more of a factor.

The differences between the two (B and D)

1. Change in wing planform - strake- due to a longer root chord - necessary to accomodate the chage in the wheel door/uplock designs.
2. Change in windscreen (sharper 31 degree angle vs 35 degrees for B) to improve aerodynamics and reduce drag due to flow stagnation at the base where it intersects cowl, and remove turtledeck to accomodate teardrop canopy.
3. Increase armament with two more /50 cal plus more ammo/gun, and install the guns vertically to reduce ammo stoppage/jams that plagued the B
4. replace the 500 pound racks with 1000 pound racks to accomodate 1000 pound boms or 110 gallon wing tanks

[drgondog]

The directional stability issue with the 51 was fixed with the H which was 13 inches longer aft of the wing, and installing the tall "H" vertical stabilizer/rudder.

The H was complete re-design to 7 1/2 G limit stress design on 8000 pounds (versus 8g @ 8000 for A/B/D)and  eliminated 600+ pounds from the airframe, making the airframe weigh less than the P-51B. The reason the H weighed essentially the same as the P-51B 'in combat ops load out" is that the H had the two more '50's plus more ammo.