investigating Gear Drag Inconsistencies

[Magic Zach]

Going to start with the 190s.
It seems that the gear drag is not significant enough when the gear come down.  Of all the warbirds, the 190s both are among those with the biggest increase in exposed surface area when down.
190A8, one gear down: -6 knots lost to top speed at SL
190A8, both gear down: -20 knots lost to top speed at SL
As you can see, not just is there a pretty minimal speed (and presumably drag increase) loss, but it's not evenly divided between each gear.  The drag does not double, but over triple when the second gear leg is dropped.
This is also the same case, and same numbers with the 190D9.  -6 knots lost with one gear down, -20 knots lost from top speed with both down.

Now that you know how this is being done...
P51, one gear down: -27 knots from top speed at SL (3000RPM, 61")
P51, both gear down: -38 knots from top speed at SL
Just like with the 190, the drag is not consistent.  However this time, instead of increasing x3.3 when a second gear leg is dropped, it only increases by x1.41.

Now here is where it gets insane...
Spitfire, both gear down: -65 knots from top speed at SL (3000RPM, max allowed boost)
I cannot try with both gear down, as I'm limited by the options in the preset failures list in the Mission Editor.  I can only drop both gears, or none at all.  Regardless, the speed lost is incredible, especially compared to the 190s.

1.42 ATA Bf 109K-4, both gear down: -83 knots from top speed at SL
As if the Spitfire had it bad enough.  But same as the Spitfire, I cannot drop a single gear leg due to limits in the ME.

Bottom line is, the apparent drag changes when undercarriages are dropped does not look consistent at all.  While the 190s and 51 (and perhaps 47, but this is an aircraft I do not own currently) have the biggest undercarriages that would present the biggest profile changes when down, get off rather lightly. In fact, when I drop single gear legs in the 190s, I barely even feel any adverse yaw.  I almost don't need to make any slip corrections.  Meanwhile, the aircraft that have the smallest undercarriages, and the smallest changes to their profile and presumably drag when dropped...get hit the hardest by the drag!  I'd think some virtual CFD testing with the models gear up and down would yield some results, but that's my hopeful idealist thinking.
 

[NineLine]

Did you save the tracks for these tests by chance?

 

[Magic Zach]

1 hour ago, NineLine said:

Did you save the tracks for these tests by chance?

 

Reran my flights and gathered these tracks

109 all gear down.trk A8 left gear and all gear down.trk D9 left gear and all gear down.trk P51 all gear down.trk P51 right gear down and TW.trk spitfire all gear down.trk

[Magic Zach]

I also want to acknowledge the tailwheels for each, particularly the 51 and 190s.  I'm aware that the TW drops when the right leg comes down, in the 190s.  However I'm doubtful that the tailwheel would inflict more drag alone than a main gear leg.

Such as with the 190s, if the left leg alone causes a drop of 6 knots, wouldn't the right leg (on its own, TW still up) cause a drop of another 6 knots, if not perhaps slightly less (since the profile drag decreases as speed decreases).  So roughly that would have a loss of 12 knots to max airspeed at SL.  The tailwheel if anything should inflict less drag than a main gear leg when extended.  However, with all the gears down in DCS, the loss in airspeed is 20 knots.  So, it seems the TW may be responsible for another 8 knots loss to max airspeed at SL.  Meanwhile a main gear leg only inflicting a 6 knots loss.

This may be similar in the 51's case.

 

This is also completely aside the fact that the drags for different aircraft are wildly differing, some having far more inflicted drag despite having a smaller profile increase (with the small undercarriages on the 109 and Spitfire).

[NineLine]

Thanks I will take a look.