Thanks for your interest in G&P Sales aircraft.
I use polyester fiberglass with mat which gives greater unidirectional strength and fewer voids than cloth does. All of the aircraft feature fiberglass fuselages.
If you will look at the pictures of the kits you will see that they are all basically designed the same way. The wings are built with 1/8" bead virgin foam and they are slotted for the spars. The fuel tank bays are cut out behind each engine. The engines mount onto what I call a leading edge spar that incorporates the firewalls into it so that it looks like a pair of dumbbells. The firewalls are then lined with 1/8" ply and attach to the main spar. This make a very ridgid structure that minimizes vibration and flexing. The fuselages require no bulkheads as they are stiff enough without them. The wing saddles require a ply plate for mounting the blind nuts that hold the wing on.
I have done a lot of testing including crashes and found that mat is excellent for rigidity and strength for amphibious aircraft. Some of the kit photos show the fuselage with white gel coat but I no longer use gel coat as it cracks easily and adds 11+ ounces to the fuselage. The wings and stabs are made of small bead 1 LB density virgin white polystyrene foam. The wing glues together into a complete unit very quickly and utilize a main 1/8" ply spar. Cockpit and blisters are made of PETG which is a much tougher material than acetate. It is virtually tear proof. The cowls & nacelles are made of polystyrene except for the Canadair, 104" PBY and PBN which have fiberglass cowls and nacelles. The kits contain just about all of the hardware needed except nyrods.
The aircraft all fly great and handle the water with ease. I designed the planes to use a water rudder because it works very well. I have used differential engine control for steering and found it quite sluggish whereas the water rudder is crisp and positive in its control. The kits are completely made by us here in the U.S. Some of the kits have a 30 or more page construction manual, or full size plans. I am currently in the process of developing a manual and full size plans for all of my kits.
The construction and flying videos contain step by step instruction in the building of the planes and each plane has its own video. These videos are also informative in showing construction techniques that you may not have tried before. Each video shows close up detail of the finished airplane and extensive flying. They run from 1-1/2 hr's. to 2 hr's. in length.
I have been building fiberglass models since 1970 and teach Manufacturing Engineering at a College in Northern California. One of the classes I teach is Fiberglass Manufacturing. I have a lot of experience with the glass medium.
My kits are unique in that I do not use much cloth except in critical high stress areas where load concentrators are a factor. Cloth provides greater tensile strength per weight, but my sea planes don't need tensile strength. They need stiff flexural strength since they are making a belly landing when they land. Also, when a plane crashes, tensile strength is virtually a non-factor. Compression is the stress applied in a crash. I have crashed many a cloth and mat fiber airplane and I can say that the difference in damage is negligible.
Epoxies and kevlar have their place, especially in marginally powered planes and gliders, but I feel the cost yields diminishing returns. The kits feature presawn ply and balsa parts where needed. The PBYs and PBN have vacuum formed floats. The Seabee has fiberglass floats and the other kits require carving the floats from balsa blocks. These kits are designed to build as fast as possible considering that they are scale aircraft and are complex models. I have designed them to be tough, as light as possible, and serviceable (access to components later on for servicing).
All of my models have had extensive flight testing by myself. They feature constant improvement as I get feed back from customers who have had minor crashes and found various items that broke. I then reinforce those areas if I need to improve durability. I produce the highest quality kits possible for the price. I think you will be pleased with them. I offer a money back guarantee and if you are disappointed with the kit I will cheerfully give you a refund. I am a life long modeler (43 years) and I build these kits for fellow modelers.
My first concern is that my customers are happy with my kits. I hope you will find the information contained on the pages of this web site helpful. If not, feel free to give me a call and I will answer all of your questions. I prefer phone calls to letters and I do answer emails.