The GBU-15 is unique it its ability to be launched from an incredible standoff range. All GBU-15s can be launched from a maximum range of 8 miles at low altitudes, and up to 20 miles at higher altitudes. The key to this relatively long range are the lift capabilities of the cruciform wings at the front and rear of the GBU-15 – effectively making it an unpowered glider.

Although not part of the F-15Es inventory during the Gulf War, some 70 GBU-15s were expended – mostly by F-111s. They were probably best known when they were used to shut off the flow of oil into the Persian Gulf by an attack on several oil manifolds near Sea Island Terminal, Kuwait.

There are two basic types of GBU-15 – the Electro-Optical (TV) guided GBU-15 (V)-1 and the Infrared Guided GBU-15 (V)-2. Each type comes in comes in a sub-type for regular and hardened targets. Although the EO-guided (V)-1 should be less effective at night, my tests have shown no difference in accuracy or effectiveness for the V-1 or V-2 variants day or night. That being said, contrast for day (use the V-1) and night missions (use the V-2) is enhanced by using the proper targeting head.

Although you can designate a target for the GBU-15 using the HUD/mouse designation method, the preferred approach is to designate your target through an HRM patch map – otherwise you negate the benefits of the GBU-15’s standoff range. The only bombing modes available for the GBU-15s are either AUTO or AUTO LOFT methods – the CDIP drop method is not available for this bomb type.

There are two modes for GBU-15 launch – DIRECT and INDIRECT:

DIRECT mode slaves the seeker head to a target based on a designation from a patch map or HUD/mouse designation. DIRECT mode, also known as "lock on before launch", has two sub-modes: Automatic weapons cueing and manual weapons cueing. DIRECT mode is very effect and you will rarely miss.

Automatic Weapons Cueing (AWC) - You simply designate your target and release the bomb when the TREL reaches 0. Target designation is automatically handed off (slaved) from the patch map target designation. For AWC to be enabled, the WEAPONS VIDEO PBs must show AUTO targeting mode and DIR weapons launch mode. The view from the WEAPONS VIDEO after launch will switch to the next GBU-15 remaining on the plane, even if you have the AN/AXQ-14 datalink pod mounted.

Manual Weapons Cueing (MWC) – Before launching the weapon, switch to the WEAPONS VIDEO MPD. Turn AUTO targeting mode off (MAN should appear) and change DIR weapons launch mode to IND (indirect weapons launch mode). With MWC, you have the ability to slew your seeker head prior to launch to designate a new target. You must remove weapons tracking by pressing the TRK PB so that it is not enabled. Then use the seeker head slew keys - PBs 3, 13, 18, 8 (left, right, up, down arrows) to move the seeker head.

After you’ve found your target new, enable tracking again by pushing the TRK PB. If you change MAN back to AUTO you will re-acquire your original target designation, so be careful. Drop the bomb as normal. The view from the WEAPONS VIDEO after launch will be from the seeker head in the dropped weapon, but you must have the AN/AXQ-14 datalink pod mounted in order to see the video through the head of the bomb. It’s really cool to watch the target rushing up!

Click to continue . . .

How to use INDIRECT mode to manually guide the bomb to target:

The F-15 manual is incorrect in stating that for INDIRECT mode, the TRANS profile allows you to control the weapon’s yaw only while the TERM profile allows you to control pitch and yaw. While this may be the way it was intended to work, the description of the launch profiles is not what is reflected in the sim. TRANS allows you to control pitch and yaw while the TERM doesn’t work at all.

The following instructions allow you to control pitch and yaw of the GBU-15. This works with both EO and IR GBU-15s.

Note** The forthcoming patch might correct this approach and make it work as intended in the manual.

1. Make sure you are in A/G master mode - enable a GBU-15 weapons station
2. Designate a target as normal
3. From the WSO seat, change the Targeting IR Pod view to WEAPONS VIDEO view
4. On the WEAPONS VIDEO MFD, change the AUTO targeting mode to MAN and change the launch mode from DIR to IND
5. Wait for the IN RANGE message to display on the MFD - Pickle weapon
6. After 2 seconds, the launch profile will change automatically from NORM to TRANS
7. Press the TRK PB so weapons tracking if now off
8. Use the PBs 3, 13, 18, 8 (left, right, up, down arrows) and choose your new target or readjust your old one
9. Once you have your new target designated, click the TRK PB to enable weapons tracking
10. Before the square drops below the second horizontal line, you MUST change the launch profile to from TRANS to TERM - after this step, nothing can be done or changed

SHACK! BURN BABY BURN!

Thanks to Alex for doing the initial research in this area.

The keyboard keys to control both the Weapon Video and Weapon Flight are not set by default; you have to enter the CUSTOM keyboard mapping area to map them to available keys.

I would suggest mapping them to available un-shifted or shifted keys - mapping them to ALT or CNTL key combinations is suspect at best if you use HOTAS gear. Look for the keys entitled WEAPON_RGT, LFT, UP and DWN for the In-flight GBU-15 steering keys and the WPN_??? keys for the Weapon video keys (to slew a Maverick or GBU-15 using the seeker's head instead of the Targeting IR POD slew).

And the Gun Ammo Choices

In case you were wondering, there are two types of cannon ammo supplied with F-15: the venerable M-56A3 and the newer PGU-28. The M-56A3 is a HEI (high explosive, incendiary) round, that travels ~3,380 fps. The PGU-28 is a SAPHEI (semi-armor piercing, high explosive, incendiary) round, travels ~3,450 fps.

In Jane’s F-15, the damage value associated with the PGU round is greater, so if you’ve got ‘em, use ‘em.

The next instalment next week will address "Attack Profiles" for ordinance delivery. Suffice to say that target type and selected munition are only part of the equation - anticipated threats and terrain features will alter the delivery profile as well! Stay tuned.

Many thanks to Ian for his assistance in verifying these techniques!

Write to Snacko with your questions and comments.