TWENTY YEARS AGO

The Herr Hopper — by Professional Fibreglass

KNIGHTS LANDING, CA — Every ag pilot dreams of a bigger hopper, especially rice pilots. Larger is not always practical, the limitations can be many, not the least of the aircraft and its powerplant. However, the 300-gallon Ag-Cat is a prime candidate for a hopper expansion. This is where Jon Herr’s Professional Fiberglass comes into play.

Jon Herr acquired his dad’s hangar in 1980. Mr. Charles Herr built and installed N3N and Stearman fiberglass hoppers during the early years of California ag aviation. Jon started with his dad when he was 14. He worked with another fiberglass repair company from 1972-1980. Upon a disagreement about the way things should be in this world, Jon formed Professional Fibreglass. Yes, he knows that Fibreglass is a unique way to spell fiberglass. But, since the English developed the fiberglass process and that’s the way they spell it, Jon figures one way is as correct as the other.

Although there was a time Professional Fibreglass traveled throughout the United States repairing and rebuilding hoppers, today the company’s work is shipped to the plant at Knights Landing, a small community a few miles north of Woodland, California.

Jon Herr with the “chopper” machine in the background that applies fiber and resin to hoppers. Jon is holding a repaired Piper Brave cowling.

To make it simple for the operator to send his hopper to Professional Fibreglass, Jon has an arrangement with several trucking companies that allows for a savings of 40-60% over normal shipping charges. All a customer has to do is contact Jon and he’ll arrange for the pickup of the hopper.

Professional Fibreglass’s speciality is the rebuild and expansion of 300-gallon Ag-Cat hoppers to a more practical 330-gallon hopper, known throughout the industry as the Herr hopper. Professional Fibreglass also manufactures the 400-gallon Ag-Cat hopper conversion for Ag-Viation and the hopper top for Delta Turbines’ 800-gallon hopper conversion for its turbine powered M18 Dromader. Other work by Professional Fibreglass includes reworking power company lift buckets, and fiberglass glare shields for the California Department of Forestry’s OV-10s.

Jon Herr and Dave Barton stand by the huge Delta Turbines’ 800-gallon Dromader hopper top.

Another style of hopper Professional Fibreglass builds is not from fiberglass, but polypropylene. This construction requires thermoplastic welding. These speciality hoppers are built for installation in Bell and Hughes helicopters. Their unique rectangle design allows for a better positioning of the CG, by constructing the hopper behind the pilot’s seats and closer to the rotor mast. Sizes range from 400-500-gallons.

For those operators of Ag-Cats with 400-gallon hoppers that have the aluminum throat of the hopper sand-casted to the fiberglass, Professional Fibreglass can rebuild these hoppers replacing the aluminum with the more practical fiberglass throat.

When a hopper comes to the Professional Fibreglass shop it is cleaned of any residual contaminates. It is then thoroughly sanded down through any impregnated contaminates until the remaining fiberglass is clean and relatively clear. If any repairs are needed, or if the cleaning process penetrated into the layers of fiberglass, these are repaired and built back to the original thickness. Many years of experience building Ag-Cat hoppers have led Professional Fibreglass to know exactly where the weak points of the older factory hopper were, allowing for reinforcement in these critical areas with the Herr hopper.

Another Herr hopper, actually a 400-gallon Ag-Viation hopper, ready for pick up.

A Herr hopper, the traditional 330-gallon unit, weighs about 225 pounds. The hopper is built-up from five layers of fiberglass made up of roving material and chopped-strand mat. This material is layered-in by hand, an almost forgotten process today.

The outside is finished with a clear resin that seals the fiberglass hopper from oil, grease, chemicals and other contaminants. The inside finish has a wax finish that is treated with a high-grade gel coating that protects the hopper from chemicals.

A new top is added, giving the hopper a 330-gallon capacity. This also includes a new hopper door and hardware.

A Herr hopper is guaranteed for one year, although undoubtedly, they last for many years without problems. Jon says the Herr hopper should last for ten or more years with proper care. He recommends washing the inside of the hopper at the end of the work day, then leaving the lid open to allow the hopper to “breathe”. UV rays ultimately breakdown fiberglass. Because of this, covering a hopper top during prolonged exposure to the sun, should extend its life. Also, high temperatures shorten a fiberglass hopper’s life.

If there is one thing that comes to mind about Jon Herr, besides his hoppers and his good natured demeanor, is the aviation calendars he has given away for so many years. There is no telling how many of those calendars grace the walls of ag operations worldwide. But, maybe there is another item about Jon Herr, and his wife, Mary Beth, that is less known. The Herrs, over a 20-year period, have been foster parents for 126 children from birth to age 14. The foster children have complimented their family of eight children, of which three are adopted foster children, the oldest and the two youngest, ranging from ages 11 to 26. It stands to reason, that Jon and Mary Beth Herr have succeeded in both life and business.

Editor’s Note: This article is dedicated to the memory of both Jon Herr (1953-2014) and DJ Herr. Tim Herr (Jon’s son) and his wife Melissa lost their son DJ on September 22, 2020. Tim and Melissa would like to express that no one is immune to feeling the negative effects of depression during this time of isolation. The Professional Fibreglass family ask that you take time to reach out to your loved ones and check in. Encourage those around you and remember that everyone deals with pain differently whether we can see it or not.

DJ Herr