Potential drag issue related to HVAR pylons

[Firebugs]

An observation:

Level flight 500-1000ft ASL, full mill power (2700 rpm, 54" hg), Oil cooler closed, Intercooler closed, cowl flaps almost completely closed, open just enough to keep cylinder head below red line.  50% fuel for all tests:

Slick: 290-295 kts

2x 500lb bombs: 250-260 kts.  Drop the bombs, return to 290-295kts

3x 500lb bombs (add center pylon): 250ish kts.  Drop the bombs, return to 290-295kts

3x 500lb bombs + 8x HVAR:  210kts.  Fire HVARS, 220kts.  Drop bombs (slick with empty pylons), 230kts

HVARs only: 230kts.  Fire all HVARS, 240kts

 

Special case, very interesting result:  Load HVARS, take off, fire HVARs (at this point, max level flight 240kts), land plane re-arm "empty" (slick).  The pylons are visually still on the plane, exactly the same condition as when you landed.  However, now the plane will fly 290-295kts level on the deck again.

 

So after loading HVARs, the pylons apparently cause ~50-60kts of drag.  Obviously these numbers may +/- probably up to 10kts because of my ability to trim or variation in cowl flaps or whatever, but I think it's quite a lot of difference if I can reliably see 50-60 kts hit just because HVARs were ever loaded on the plane. 

[-Rudel-]

Hi, we'll take a look.

[anlq]

23 hours ago, -Rudel- said:

Hi, we'll take a look.

I can confirm there is a problem with drag/payload after firing all of them. It seems drag/payload are not cleared after firing. So the aircraft remains slow.