Are Zuni Rockets so Heavy?

[GrEaSeLiTeNiN]

Hi,

 

I noticed the minute I load Zuni rockets on one wing, that wing dips in flight even with the loadout configuration below. Are Zunis that heavy?

 

Left Wing (from inside outwards): 1xGBU10 | 1xHARM

Right Wing (from inside outwards): 1xAGM65F | 4xZuni (this wing dips in flight)

All else equal

 

Seems strange because visually, the GBU and HARM look much bigger than the AGM and Zunis.

Edited March 31, 2019 by GrEaSeLiTeNiN

[Eldur]

Check your loading screen while selecting those as the weight numbers change immediately. For example, take that loadout and then check weight. Replace the right wing things with the stuff you also have on the left one and check again.

[Tomsk]

The other thing that may affect this is the zunis are insanely draggy. Don't know if it's realistic, but you really notice the different in top speed when carrying zunis. Like I seem to recall you can't even break mach 1.0 on burners at sea level with 4x zunis.

[DeathAngel1]

Yes, they are. Its 4x127mm in launcher, so its heavy.

[Mad Dog 7.62]

The rocket and warheads are about 107 lb. each, so x 4 + launcher should put a pod of them at about 500 lbs. They are going to be draggier than a Mk82, but about the same weight. I wonder if the ingame drag coefficient is bugged though.

[SirJ]

when looking at the drag coefficient a streamline body (ideal) has <0.17 (give a bit then you end up at a mk82) compared to a longer than width cylinder 0.82 (again add smth to get a zuni launcher).

So you end up at approx. ~4times the drag coefficient for the same diameter...

 

 

Looks valid to me to be quite draggy...

 

 

edit: valid Cd for Mk82: https://apps.dtic.mil/dtic/tr/fulltext/u2/a329921.pdf

Edited March 31, 2019 by SirJ

[Ramsay]

I noticed the minute I load Zuni rockets on one wing, that wing dips in flight even with the loadout configuration below. Are Zunis that heavy?

 

TL;DR:

 

Not AFAIK, it looks like the DCS Zuni's are overweight as the BRU33+LAU10+4xZUNI is 1144 lb in the ME.

 

Looking in DCS World\CoreMods\aircraft\AircraftWeaponPack\rockets.lua

 

• "LAU-10 - 4 ZUNI MK 71" ... mass=440 kg (970 lb)

 

seems high as ...

 

• 4x 5-inch Zuni = LAU10 148lb + 4x Zuni ((Mk 63, Mk 71 Mod 1, Mk 93) 138lb = 700 lb

 

Detail

 

Left Wing (from inside outwards): 1xGBU10 | 1xHARM

Right Wing (from inside outwards): 1xAGM65F | 4xZuni (this wing dips in flight)

 

Left Wing

• GBU10 2153lb = 2153lb *

• Harm 800lb + LAU118 100lb = 900lb

 

Right Wing

• AGM65F 669lb + LAU117 135lb = 804 lb

• 4x 5-inch Zuni = BRU33 175lb + LAU10 148lb + 4x Zuni ((Mk 63, Mk 71 Mod 1, Mk 93) 138lb = 875 lb

 

* GBU-10 Notes (for info):

• "DCS World\Scripts\Database\db_weapons_data.lua" models the "GBU-10" as 1162kg (2561 lb)

• "DCS World\Scripts\Database\Weapons\bombs_table.lua" models the "GBU_10" as 934kg (2059 lb)

• "DCS World\Scripts\Database\Weapons\bombs_data.lua" models the "GBU_10" as 900kg (1984 lb)

 

DCS's Zuni in Detail

Using the ME to add and remove loadouts

 

• 4x 5-inch Zuni + BRU33 = 5,741 - 4,597 = 1,144 lb

 

• 2x 4 Zuni + BRU33 = 6711 - 4,597 = 2114

 

Therefore 1x LAU10 (loaded) = 2114-1,144 = 970 lb

and the BRU33 = 1,144-970 = 174 lb

 

Each rocket fired reduced weight (DDI checklist) by 106 lb (48kg)

 

• 4x 106 lb = 424 lb

 

so the empty LAU10 = 970 - 424 = 546 lb i.e. much more than it's real weight.

 

Tested using the F-18C in DCS 2.5.4.29079 Open Beta

Edited April 1, 2019 by Ramsay
Add info on different GBU-10 weights as modelled in DCS

[Eldur]

when looking at the drag coefficient a streamline body (ideal) has <0.17 (give a bit then you end up at a mk82) compared to a longer than width cylinder 0.82 (again add smth to get a zuni launcher).

So you end up at approx. ~4times the drag coefficient for the same diameter...

 

 

Looks valid to me to be quite draggy...

 

 

edit: valid Cd for Mk82: https://apps.dtic.mil/dtic/tr/fulltext/u2/a329921.pdf

 

There are aerodynamic caps on them IRL for a reason though...

[SirJ]

@Eldur:

Is there a cover sealing all 4 rockets plus launcher at the front?

[GrEaSeLiTeNiN]

Even this causes the right wing to dip.

 

[GrEaSeLiTeNiN]

This would have been better, lol

 

[SirJ]

anyone tried to rudder trim for it?

 

 

if one side is draggy a yaw moment is induced...this leeds the other wing to see higher relative velocity and higher lift...can be seen during decrap manover at high crosswind landings...

[GrEaSeLiTeNiN]

Are Zuni Rockets so Heavy?

 

anyone tried to rudder trim for it?

 

 

if one side is draggy a yaw moment is induced...this leeds the other wing to see higher relative velocity and higher lift...can be seen during decrap manover at high crosswind landings...

 

 

 

I don’t notice yaw but immediate roll hence seems more like a weight issue? Or it could be drag related too. In any case, I’m just wondering if ED has checked whether the Zunis are modeled correctly in this regard.

[Vitormouraa]

TL;DR:

 

Not AFAIK, it looks like the DCS Zuni's are overweight as the BRU33+LAU10+4xZUNI is 1144 lb in the ME.

 

Looking in DCS World\CoreMods\aircraft\AircraftWeaponPack\rockets.lua

 

• "LAU-10 - 4 ZUNI MK 71" ... mass=440 kg (970 lb)

 

seems high as ...

 

• 4x 5-inch Zuni = LAU10 148lb + 4x Zuni ((Mk 63, Mk 71 Mod 1, Mk 93) 138lb = 700 lb

 

Detail

 

 

 

Left Wing

• GBU10 2153lb = 2153lb *

• Harm 800lb + LAU118 100lb = 900lb

 

Right Wing

• AGM65F 669lb + LAU117 135lb = 804 lb

• 4x 5-inch Zuni = BRU33 175lb + LAU10 148lb + 4x Zuni ((Mk 63, Mk 71 Mod 1, Mk 93) 138lb = 875 lb

 

* GBU-10 Notes (for info):

• "DCS World\Scripts\Database\db_weapons_data.lua" models the "GBU-10" as 1162kg (2561 lb)

• "DCS World\Scripts\Database\Weapons\bombs_table.lua" models the "GBU_10" as 934kg (2059 lb)

• "DCS World\Scripts\Database\Weapons\bombs_data.lua" models the "GBU_10" as 900kg (1984 lb)

 

DCS's Zuni in Detail

Using the ME to add and remove loadouts

 

• 4x 5-inch Zuni + BRU33 = 5,741 - 4,597 = 1,144 lb

 

• 2x 4 Zuni + BRU33 = 6711 - 4,597 = 2114

 

Therefore 1x LAU10 (loaded) = 2114-1,144 = 970 lb

and the BRU33 = 1,144-970 = 174 lb

 

Each rocket fired reduced weight (DDI checklist) by 106 lb (48kg)

 

• 4x 106 lb = 424 lb

 

so the empty LAU10 = 970 - 424 = 546 lb i.e. much more than it's real weight.

 

Tested using the F-18C in DCS 2.5.4.29079 Open Beta

 

Thank you for posting this. This needs to be addressed quickly. :thumbup:

[Eldur]

@Eldur:

Is there a cover sealing all 4 rockets plus launcher at the front?

 

Looks like this:

 

 

http://vnfa2.tripod.com/VNFA-Zuni.html

 

At least in case of the LAU-3, we have that in DCS already (not sure about aerodynamics though), but just if you put them on the F-5 or Harrier.