Just wanted to note that I usually fly with tracers off, and when I fired rockets from a P-51D, there were no smoke trails from the rockets either. Not sure if they're completely unmodelled yet, or if they're off because normal tracers are off, in which case there's a bug.
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System Information
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Operating System: Windows XP Professional (5.1, Build 2600) Service Pack 1 (2600.xpsp2.030422-1633)
Language: English (Regional Setting: English)
System Manufacturer: ASUSTeK Computer INC.
System Model: A7N8X2.0
BIOS: Phoenix - AwardBIOS v6.00PG
Processor: AMD Athlon(tm) XP 2600+, MMX, 3DNow, ~2.1GHz
Memory: 512MB RAM
Page File: 153MB used, 1097MB available
Windows Dir: C:\WINDOWS
DirectX Version: DirectX 9.0 (4.09.0000.0900)
DX Setup Parameters: Not found
DxDiag Version: 5.03.0000.0900 32bit Unicode
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Display Devices
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Card name: RADEON 9500
Manufacturer: ATI Technologies Inc.
Chip type: Radeon 9500AGP (AD)
DAC type: Internal DAC(400MHz)
Device Key: Enum\PCI\VEN_1002&DEV_4144&SUBSYS_7C07174B&REV_00
Display Memory: 128.0 MB
Current Mode: 1600 x 1200 (32 bit) (85Hz)
Monitor: Plug and Play Monitor
Monitor Max Res: 1600,1200
Driver Name: ati2dvag.dll
Driver Version: 6.14.0001.6307 (English)
DDI Version: 9 (or higher)
Driver Attributes: Final Retail
Driver Date/Size: 2/28/2003 22:39:22, 272512 bytes
WHQL Logo'd: n/a
WHQL Date Stamp: n/a
VDD: n/a
Mini VDD: ati2mtag.sys
Mini VDD Date: 2/28/2003 22:38:56, 576512 bytes
Device Identifier: {D7B71EE2-0204-11CF-586C-065CA1C2CB35}
Vendor ID: 0x1002
Device ID: 0x4144
SubSys ID: 0x7C07174B
Revision ID: 0x0000
Revision ID: 0x0000
Video Accel: ModeMPEG2_C ModeMPEG2_D