3500 Straights
AEROCET 3500 floats are certified on Cessna 180’s (1957 and later), 185's and 206's, with recent certifications on Cessna 182's and the Found Bushhawk.
The AEROCET 3500 floats have exceeded all of our expectations in performance. The 3500's cruise at roughly the same speeds as Edo 2960's yet provide the safety of operation at gross weight that only a large displacement float offers. The floats are incredibly slippery out of the water giving that high lake, low power, gross weight condition some extra needed help.
With hundreds of seaplane pilots who have already flown the AEROCET 3500's, we have received almost always the same comments. "These floats are so quick on the step, they continue to accelerate when other floats would stop, and I don't feel the pronounced acceleration when I leave the water (low drag). Also the sweet spot (pitch sensitivity) is huge making them easy to learn on and step turns are a breeze. The floats are very comfortable with no surprises."
The 3500's were designed by first interviewing a large number of operators, mostly commercial and some private. The size of the float, deadrise angles (that's the angle from the chine to the keel), the afterbody angle (the angle from the step to the stern), deck design, strut layout, rudder design, spreader bars, materials, lockers, width, etc. came from these interviews. This basic information allowed us at AEROCET to comply with their wish lists making many little changes, major float material changes, yet keep the conservative twin float overall profile proven over decades of use.
The size of the float (displacement) was dictated by the Cessna 206 needs. The 3500's are easy to read when loading, giving the commercial operator a good idea of both CG location and gross weight. This has proven important where hard to read floats will allow the plane to get off the water yet have very marginal climb rates once out of ground effect.
The deadrise angle decision is very critical. Again this is the angle between the chine (the outside lower edge of the float and the keel). The greater the deadrise angle (deeper the Vee) the harder it is to get off because the float will not move up out of the water as fast. On the other hand the greater the deadrise angle the softer the ride is in rough water. A softer ride is nice yet on the other hand the amount of time that the aircraft is subject to rough water, because it will not get out as quickly, brings on fatigue to the aircraft and floats. The most popular deadrise angle by those interviewed (75%) was 24 degrees. This is the deadrise chosen by EDO. Most of the other floats have larger deadrise angles and have proven to be softer in rough water yet not good performers when it comes to getting off the water quickly. We chose to follow the popular 24 degree deadrise angle with a full double fluted bottom. It is interesting to note that the deadrise increases on our floats as you move toward the bow from the step. This allows one to smooth out the rough water by landing relatively flat allowing the bows to cut the rough water. AEROCET 3500's, because of their slippery (no rivet drag) bottoms have reduced the tendency to nose over in nose low, full flap landings allowing the operator to use the high deadrise angles on the bow of the floats for rough water.
A high afterbody angle (7.8 degrees) was chosen for the AEROCET 3500 series to allow for good rotation on take-off and for full stall landings. A very popular float for Cessna 180 and 185's has the major drawback of easily rotating into the heals of the float on take-off even though the airplane is in a position to fly. It may be of interest that we demonstrate take-offs in the 185 on AEROCET 3500's never coming up on the step, keeping the heals forced in the water. The plane will continue to accelerate and take-off provided your not loaded too heavy.
The obvious preference by all was to have nice flat top decks to walk on and as much anti-skid as possible to keep the slippage to a minimum. All operators were pleased with the strut layouts of all the popular floats in the field yet thought it would be novel if they could use their existing installation hardware and retrofit our floats to it. This was done with the most popular metal float in our displacement category. We did change any hardware in our installation to better corrosion resistant materials and on our 206 installation sized up the rear struts to provide additional strength. Spreader bars were improved with an internal shear web to protect the extrusion from crushing with forklift loads and clamping loads where they attach. Many spreader bars would fatigue on the leading and trailing edges, cracking and corroding. Composite floats also have the advantage of using stainless steel without the dissimilar metal corrosion problem. This was taken advantage of.
 Many questions have come to us about the use of these floats on Cessna 180's. The comment that we receive is that they are too big (overfloated). Is this such a bad problem, we ask in return. The first thought is that AEROCET 3500's will not get out of the water as fast as say an EDO 2870. In flight test, we found that the 180's at light weight perform closely to 2870's. But with any load at all the AEROCET 3500's easily outperform their counterparts. We feel that the 3500's are so buoyant that they don't have to climb up the big hill to get up on the step. We have been able to take-off at 3350 lbs. on glassy water at 2300 rpm and 22" with our 185. The record with light loads is 2100 rpm and 20" of manifold pressure on glassy water by Dave Hilty from Kodiak, Alaska. They might be big but they are slippery.
 The second thought is that they are so big that they will be slow in the air. As already stated we have found them to be almost identical in speed to 2960's running side by side. Remember there are no tiller posts hanging in the air, rivet drag, and they have an aerodynamic flush bumper setup. Claims by one AEROCET owner with a direct switch over from EDO 3430's is that he gained 10 mph.
The next question is weight. The 3500's, which weigh 490 lbs. with complete rigging, are designed to handle the higher Cessna 206 gross weights and their higher stall speeds. Remember that a Cessna 180 has the same wing area as a 206. Float strength is designed by both weight and stall speed. We felt that there was room to drop 40 lbs. of weight out of the floats and still match the strength required for these lighter applications thus coming within approximately 15 lbs. of the weight of the EDO 2960's. These lighter floats have been designated 3500L's and weigh 448 lbs. The floats have been tested and have FAA approval at this time. The advantages of the larger floats is safety. Buoyancy is what it's all about when you have four people, a load of fuel and baggage with the wind blowing. Plus they have huge baggage compartments. Finally, the 180 crowd has a great larger float. Both the 180's and the 185's are approved on the 3500L's.
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