UFO? - Nah, just a flying radome!

by Mike Gombert

Sputnik was first - but we were better! Sometime in the 70's (early) there was a leak in the CM (countermeasures) waveguide system on the AN/FPS-26A heightfinder radar. The waveguide/antenna system used SF6 (sulfurhexaflouride) gas as a pressurizer/dessicant. Anyhow, it was a LOW pressure system. If I remember right, it was pressurized to about 6 PSI. There was a slow leak somewhere in the system and we could not find it, we hunted for it for weeks by soaping every joint all to no avail! One afternoon I and another troop ( I can't remember who) were looking for the leak, we mentioned to the tech-rep, Jim Regal, that we were having trouble finding the leak. He suggested we pressurize the system to 20 PSI (Jim was being sarcastic, I'm sure) and I bet you'll find the leak!!

Well, being a dumb A2C, I did pressurize the LOW pressure system to about 20 PSI, and went looking for the leak. Very quickly we noticed the pressure was increasing to about 18 PSI and then dropping to 2 PSI, or so! We started looking at all the waveguide joints and finally worked our way out onto the catwalk around the main radome, following the CM waveguide to the CW antenna pedestal.

The CM radome was a reinforced fiberglass unit that was about 4 foot high and had a diameter of about 30 inches. It was held onto the antenna pedestal by a morman clamp that wrapped around the lip of the radome and the lip of the pedestal. Well, we quickly found out why the pressure was fluctuating!! The radome was raising from the pedestal when the pressure was too high and then when the pressure dropped the morman clamp would pull the radome back down to the pedestal! We both realized this was not right!! I ran back into the tower to shut off the gas -while my sidekick watched the radome (as if he could do something) I was too late, by the time I got to the SF6 bottle, the pressure was zero! I ran back to the radome only to find my sidekick sitting on the catwalk holding his head with a nice abrasion where the radome, upon its launch scraped his forehead and drew blood. The radome had separated at the flange and shot higher than the 26 radome, made a nice arc and landed down the hill on the north side of the 26 tower. After regaining some sort of composure and getting a Band-Aid for my sidekick, I went to the CEM Superintendent's office (SMSGT Royer) where the NCOIC of the 26 tower (SSGT David Schumacher) was in a meeting. I announced that I had launched the CM radome!!!!! All hell broke loose, I want you to realize that the Russians could attack at any time and the CM system was DOWN!!! The Air Force, when they ordered the AN/FPS-26A, believed that they would never need a replacement CM radome. Therefore, no radome was available in the supply system! We finally took the broken radome (it looked like a hard-boiled egg that had been dropped on the floor) into a automotive repair shop in Minot and had it re-fiberglassed.

Mike