reported AIM-9 drag

[Swift.]

When AIM-9 are loaded on the wingtip launchers, the drag of the airframe should reduce. This causes the expected onspeed to reduce by about 2 knots due to the sidewinders acting as winglets (source: Anon hornet pilot)

 

Expected behaviour:

Reduction of onspeed IAS by 2kts

Possible increase in max speed

 

Displayed behaviour:

Onspeed without winders = 144

Onspeed with winders = 145

Max AB speed without winders = 669

Mac AB speed with winders = 662

 

Here we can see that the drag on wingtip sidewinders is modelled incorrectly and is increasing the overall drag rather than decreasing it as it should.

 

This in course raises the question of whether Interference drag has been modelled as well or whether it is only the pure store drag that is modelled.

[Swift.]

For those curious this info can be found in

A1-F18AC-NFM-200

page II-8

Figure 11-2. Summary of Store Drag Index Numbers

[Swift.]

And further information:

A1-F18AC-NFM-500 from 1999

Page 58 Landing Approach Speed

'Increase Approach speed by 2 knots if wingtip AIM-9's are off'

[BIGNEWY]

Can you attach the track replay from your tests.

 

thanks

[Swift.]

Second round of testing, this time I added a weight adjusted onspeed test at 1000ft. Max speeds done at AB @ 6000ft again weight adjusted.

 

WindersOnspeedWeightAdjusted = 143-144 (141-142 expected assuming NWOsWA is correct)

NoWindersOnspeedWeightAdjusted = 143-144

WindersMaxWeightAdjusted = 662

NoWindersMaxWeightAdjusted = 669

NoWindersOnspeedWeightAdjusted.trk

WindersOnspeedWeightAdjusted.trk

WindersMaxWeightAdjusted.trk

NoWindersMaxWeightAdjusted.trk

[Ahmed]

Hi,

 

As the FM is scheduled for review:

 

Currently in DCS, the following results are obtained, as evidenced by the attached tracks:

- 2x Wingtip AIM-9: 678 KCAS
- 2x LAU-115 with 1 AIM-9 each: 678 KCAS

- 2x LAU-115 with 2 AIM-9 each: 678 KCAS 

 

rising 2 points:

 

1) Quick examination of the lua files shows that the functions defining LAU-115/LAU-127 loadouts add the same drag constant regardless of number of missiles loaded.

 

2) Wingtip (LAU-7) AIM-9 should have lower drag than LAU-115+LAU-127+AIM-9 (ref NFM-210/-200).

 

 

aim9_lau115_1.trk aim9_lau115_2.trk aim9_wingtip.trk

[Hulkbust44]

Yep, it's more or less the same story with the AMRAAMs.

Mobius708

[BIGNEWY]

reported

 

thank you

[BIGNEWY]

threads merged