Rise-Off-Water Secrets - How to Fly Those Hydro Gassies
1963 Annual Edition American Modeler
Flying a model airplane off snow with a set of skis and flying a model airplane off water with a set of floats are two things I though that by the time I was this age would have already been accomplished. It was just last year that I managed to pull off the snow skis, but I have yet to fly from floats. There's no good reason for it other than for 54 years everything else seems to have take priority. It's shameful, I know. Maybe by age 55... This article from the 1963 Annual edition of American Modeler presents two plans types and three installation configuration types for adding floats to your model. These particular models are free flight, but the same basic principles apply to just about any standard design airplane.|
Rise-Off-Water Secrets - How to Fly Those Hydro Gassies
Float #1 is tops in popularity (below). A large single forward float and twin tail floats are used. Front float is wide and shallow, while rear ones are narrower and deeper. The front float resists waterlooping while taxiing and the deep rear ones help keep the stab and rear of fuselage dry. Sled-type stepless floats are simple to build and offer minimum takeoff problems.
Float Type #1
Float Type #2Float # 2 (below) uses twin forward floats and a single one behind. Cut the width of the front float from Design # 1 in half to find width of each forward float for this setup. Add together the width of the two narrow rear floats from Design 1, to make the single tail float. Single 1/4" dia. wire struts with a 1/16" dia. angle bracer are satisfactory for models up to 25 oz. For larger models use double struts on each float. Sides may be of 1/8" balsa, with 1/16" on top and bottom. Apply silk on the bottoms and dope until the float sheds water well. Waxing after you have finished doping is advisable on any float.
Float Type #3
Design #3 (left) will give you those long shallow scale-type takeoffs. Main wire parts should be made from 1/16" wire for models up to 20 oz., from 1/8" wire for models 50 to 60 oz. All cross-bracing can be done with .020 to .040" wire.
The exciting art of flying a model off the water has its own special tricks. We hope, though, that we can dispel the idea held by many plane builders that "ROW flying is not for me." There are a few basic points to watch, then you can really enjoy rise-off-water competition.
Simple Float Plan
Primary requirement is that the floats be large enough. Second, you must attach these floats rigidly so they will not spread apart or change their angle when your model takes off. Last, but just as important as the other two requirements, the floats must have the proper angle in relation to the thrust line or your model may never get airborne.
Decide first what "type" of take-off you desire. Do you want your model to skim along for a considerable distance before finally breaking free? This sort or takeoff would be preferred for scale, sport and R/C models. For such ROW work the floats should resemble the "Edo" type, the long narrow streamlined sort used on full sized planes.
Where the model should get off the water just as quickly as possible - as is the case in contest flying - one of several 3-float layouts may be utilized. The two main arrangements depend upon where the single large float is placed, at front or rear of the plane. Use of a single float at front, with two much smaller ones at the tips of the stabilizer seems most satisfactory. The attachment for a single front float is simpler and the weight is less. Mounting gear should permit the large front Boat to be adjusted for maximum or minimum angle; the former will give the best and fastest takeoff, while a lower angle will give less wind resistance and hence a better glide. Try various angles to see which will give you the best duration.
Traditional Float Style Plans
Many ROW models suffer from lack of waterproofing - the builder keeping weight down by going light on the dope. However, as soon as such a model is put on the water it will take up enough moisture to more than offset the weight of dope that was saved! If the model fails to ROW on the first try, it will probably never get off the water till it is well dried out.
Also: When a model with insufficient waterproofing gets wet, the balsa is softened, and when the covering tightens again, warps are bound to result. Castor oil added in small quantities to the dope will make the doped surfaces more water repellent, and will also prevent warping that occurs with a heavily doped surface on a light frame. Add the oil a few drops at a time: too much will make the surface very tacky.
A set of floats will often outlast several models, so it is smart to do a good job of building and finishing.
What engine size is best for ROW competition? If you pick a Class A size model power it with an engine of perhaps .23 capacity when you add floats then you will have enough extra power to get off the water quickly. Many a good float plane designed to minimum requirements will dunk occasionally, whereas if it had a little more power it would hop off the water quickly every time.
Always use the floats when you are test flying an ROW model, first make your tests glides over soft long grass to prevent damage. While undertaking these early tests, set the floats at a rather high angle. This will slow down the plane somewhat. making flight adjustments easier. When you have the flight pattern under control you can try an ROW flight. If you are new at this. there is one precaution you must remember - DON'T push the plane to "help" the takeoff. It will most surely prevent a takeoff. With the high float angle mentioned above, the plane will probable take off easily, and successive flights can be made with less and less angle to the main float to improve the glide. At the same time, add negative angle to the stab, bit by bit, until you get the best possible glide while still retaining good ROW characteristics.
The Edo type floats should not be set at too shallow an angle, as the takeoff will be much longer. These floats must ride with the nose quite high out of the water to keep from dunking.
Final points to consider: Short-coupled models give the highest angle of attack to the wing, and therefore assure fastest takeoffs. Long models require a long takeoff run, which means much more chance of dunking. The rear floats should be arranged to allow the highest possible angle of attack. All float attachments should be absolutely rigid so that float angle and alignment do not shift as the model scoots over the water. Strut attachments should be bound and cemented (even fiberglassed) to the basic float structure, then covered. Plenty of coats of dope will waterproof the floats as well as harden and protect the balsa. And remember - when launching, don't push!
Posted October 13, 2012