Photos of Honeywell Ring Laser Gyro-Based Inertial Reference Units
[Only about 3 people per decade visit the Laser Equipment Gallery ;-), the existing format is archaic, and I am lazy. So going forward, we will use the Windows App "Web Album Generator" for most of the collections.]Note: Most links open in a single new tab or window depending on your browser's settings.
These are photos of Honeywell navigational Inertial Reference Units (IRUs)
or parts of them that use HeNe laser-based Ring Laser Gyroscopes (RLGs).
The heart of an IRU is the Inertial Platform (IP). This photo shows the
three major types of Honeywell IPs
Honeywell Inertial Platforms (IPs) Through the Ages
The Triple RLGs inside each IP are from left to right:
GG1342, GG1320, and GG1308
The GG1342 RLG is used in the LASEREF I-II IRUs, while the GG1320 is used in the LASEREF III-VI IRUs. Although the GG1320 is much smaller and lighter than the GG1342, it has similar or better performance. LASEREFs are intended for civilian and military aircraft. The GG1308 is lower cost with a shorter life and is used in guided munitions and the like, so there are no photos of a complete IRU using this IP as eBay doesn't tend to have many listings for used or previously-owned missiles. ;-) However, it is believed that the triple GG1308 IP provides most of the functions of a complete IRU.
The GG1342 RLG IP weighs nearly 20 pounds. In the photo, 2 of the 3 RLGS are visible with the third underneath. The GG1320 RLG IP is around 7 pounds with all three RLGs visible. And the GG1308 RLG IP is only around 1.5 pounds with the RLGs fully enclosed in the metal can. All have the the corresponding X,Y,Zaccelerometers buried inside as well. And in fact, the CC1320 RLG IP. and especially the GG1308 RLG IP probably include many of the other funtions of the original entire LASEREF box that are not part of its IP. Thank Moore's in part for that. ;-)
Much more information on GG1342, GG1320, and GG1308 RLGs themselves may be found at Sam's Laser FAQ Chapter: Laser Intruments and Applications in the sections starting with "Ring Laser Gyros". And for more photos of Honeywell RLGs than available anywhere else in the explored Universe, see Helium-Neon Ring Laser Gyros.
Here is a summary of what's been found out so far on LASEREFs:
Model RLG Size (in) Weight (lb) Description Comments ------------------------------------------------------------------------------ LASEREF GG1342 13x13.5x7 42.5 First version LASEREF I GG1342 13x13.5x7 42.5 Same as LASEREF I? LASEREF II GG1342 13x13.5x7 42.0 LASEREF III GG1320 4.8x7.64x15.12 27.0 LASEREF IV GG1320 4.8x7.64x15.12 17.1 Web Copy LASEREF V GG1320 6.5x6.4x6.4 9.8 Web Copy LASEREF VI GG1320 6.5x6.4x6.4 9.3 Web Copy Latest as of 2022
If any of the three people who have visited here recently ;-) have more information on IRUs and RLGs including documentation on other LASEREF versions - or a LASEREF (any model, any condition, or just parts) they no longer need, please contact me via the Sci.Electronics.Repair FAQ Email Links Page.
Honeywell LASEREF Inertial Measurement Unit
This model is believed to be the first commercial IRU from Honeywell and similar or identical to LASEREF 1 (and probably LASEREF 2). It uses three of the workhorse GG1342 RLGs which are fully documented via the links above. The GG1342 RLG may still be in production over 40 years since it was developed. See links above.
This unit weighs in at 42.5 pounds - which is even printed on the label so no one sprains their back lifting it (or to balance the mass in an aircraft). And although photos of this thing make it appear to be huge, the box itself (excluding the handles, etc.) is only around 12-1/2 W x 13 D x 7-1/2 H inches. The modern replacement - LASEREF VI - is less than 1/4th the size and weight. But they don't show up on eBay. Darn, shipping would be lower. ;-) (However, photos of the inertial platform from a more modern Honeywell IRU are in the section: Honeywell GG1320 RLG-Based Inertial Platform. Coming soon.)
There are separate albums for the main unit, inertial platform removed from it, main chassis PCBs, and power supply module. These photos are just the preview:
Honeywell LASEREF Inertial Reference Unit: Outside (left), Inside (left-center), Major Subassemblies (right-center), GG1342 RLG-Based Inertial Platform (right)
Everything is present in the parts photo except for the top and bottom covers and a few screws. The oriental carpet should give it more class than the photo on page 36 of Blazing Gyro - The Evolution of Strapdown Inertial Navigation Technology for Aircraft. However, most of the circuit boards differ, likely due to the more recent vintage of this unit. (That article also includes extensive historical information on the development of the first Honeywell RLG-based IRU presented with a wee bit of humor thrown in.)
But here is more good stuff:
- Honeywell LASEREF Inertial
Measurement Unit Assembly (Web Album, 28 photos).
This is the state of affairs with the top and bottom covers removed. They are held in place with at least 30 captive screws each, yet the thing is not even slightly environmentally sealed. ;-) Nonetheless, after some 28 years, the only noticeable dust was on the white cables connecting the high voltage power supplies to the RLGs. The large number of screws may be make sure the cover is in electrical contact with the chassis provide some RFI shielding.
- LASEREF IRU GG1342 RLG-Based Inertial
Platform (IP) (Web Album, 15 photos).
The three accelerometers are buried inside and they are staying there. ;-).
Extracting the IP from the IRU requires removing 6 cap-head screws on the top and 3 cap-head screws on the bottom and then prying. :( It's possible to use 4-40 screws in selected case screw holes to do the prying by bottoming against the main casting. But beware that those above the IP PCB cannot be used for this purpose as they do not bottom on the case and will damage the PCB. Don't ask how I found out. There is actually a slot on the front and a hole on the side of the main case apparently for this purpose, though strategic jiggling would probably free it (mainly from the backplate connector).
- LASEREF IRU Main Chassis PCBs
(Web Album, 11 photos). A1 and A4-A8 are in the card cage at the front-left,
A13 is in the back-right, and A15 is at back-center.
- LASEREF IRU Power Supply Module (Web Album, 11 photos). This plugs into the backplane like the other PCBs but is secured with a pair of cap-head screws top and bottom each.
Honeywell GG1320-Based Inertial Platform
This is believed to be from some version of a LASEREF IRU and similer to what's in the photo of the guts of the LASEREF IV shown on page 9 of LASEREF IV Inertial Reference System: Product Description or Sam's Copy of LASEREF IV Inertial Navigation System: Product Description. (The "I" rather then "IV" must be a typo - and this is a Honeywell publication!). Like the GG1342 RLG-based inertial platform, above, there are 3 accelerometers buried inside. The GG1320 is the current (as of 2022) generation of high precision RLGs from Honeywell and is extensively documented in the RLG links, above.
LASEREF V and LASEREF VI also use a similar IP. See for example: LASEREF V Inertial Navigation System (ManualZZ) or Sam's Copy of LASEREF V Inertial Navigation System. The major assemblies are shown on page 12. Besides the IP (called the "Inertial Sensor Assembly" in the manual), the only electronics are the "Power Supply/EMI Transient Suppression" and "Processor and ARINC I/O". LASEREF VI has the same external appearance but I've not been able locate much on the technology other than that it does use GG1320 RLGs. It is a bit lighter in weight likely due to later generation electronics. The datasheet may be found at Honeywell LASEREF VI Product Description 2016 and Sam's Copy of LASEREF V Inertial Navigation System Product Description.
Honeywell GG1320 RLG-Based Inertial Platform
Additional views may be found in the Web Album below:
- LASEREF GG1320 RLG-Based Inertial Platform (Web Album, 15 photos).
But the interesting stuff including numerous interior views is on the Helium Neon Ring Laser Gyros page.
Honeywell GG1308-Based Inertial Platform
The GG1308 is used in a miniaturized low cost inertial platforms like the HG1700A developed for applications like missiles and smart bombs. Live fast and die. Poor things. ;( ;-) The HG1700 has 3 GG1308 RLGs, 3 vibrating beam quartz accelerometers, and associated power supplies and communications electronics all in a package around 4x4x4 inches overall and weighing less than 2 pounds.
Honeywell HG1700A GG1308 RLG-Based Inertial Platform
Additional exterior and numerous interior views of the HG1700A may be found on the Helium Neon Ring Laser Gyros page.