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A Tale of Two Elevations

Most soaring participants cannot believe my argument that 2 soaring universes existfor our toy sailplanes. They think that flying is flying, and the experience of (random trial

and error) conditioned and reinforced by academias professionals is better than

engineered and controlled trial and error.

Unfortunately the complexity of the majority, because of advanced life styles, with

their desire for full state of art toys (all the whistle and bells) blinds them to details ofwhat has actually happened to their soaring toys. Locked into a paradigm they rationalize

that they are doing duration (i.e. the title of their task), by the employment of

performance efficiency. Thus they fly handicapped - promoting the use of extreme skills toperform menial duration tasks. To add to that complexity, they attempt to convert the

model into a miniature aircraft, and have it venture into a full size sailplanes territory

(which tends to filter out models that were designed as vocational adult toys i.e. without

professionalism). This snobbery totally blinds the major soaring fraternity to the fact that

the size of the soaring universe really dedicates the tactics of prolonging flight (duration),and that there are two basic programs that yields success.

1) Full size sailplanes and models that emulate them: They launch into the upper

air, and typically work air from 1000 ft to cloud base. This is an unlimited soaring

world -where the disadvantaged grounded pilot has only his eyesight the limit.

2) Model sailplanes that are more related to soaring birds than full size sailplanes:

They launch to a low altitude (200 ft AGL typ.) and concentrate on climbout,

rather then performance, for duration (where performance does yield benefits,but must be compromised/balanced for maximizing duration).

Now when I bring up my point that there appears to be two complete differentworlds for soaring, most think I have lost my marbles. Lift is lift - and it makes no

difference what altitude, is a common attitude; and one that I will attempt here to dispel.

I chose to be a sport flier and design and build my own equipment while using

many fields that are available to me; that are a bit smaller than ideal. I believe this is a

better condition for entry level flying than attempting to fly the high launch with equipmentthat is machine made, expensive, and is not easily repaired. This state of affairs of flying a

lower launch to fit the small field has made me aware that to capitalize on these conditions

some design constraints must be examined.

As the hand launch pilots are aware, low altitude thermals are merely feeders for a

main body of lift that will exist in the upper air. Some of these lower thermals will

dissipate, whereas others may cumulatively bust through an inversion layer and combine toreinforce a main body of lift. These feeder thermals are the prime target for the typical low

launcher. Most pilots believe the smallness of the HL machines is the secret for working

the low lift; whereas the reality is that there is only one variable that controls success (andwingspan, profile design, or fuselage length is not it). It is airspeed primarily! To fly the

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small thermals one needs to turn tight, but without a large bank angle - and slow flight is

the only way to obtain this state. Size is an important factor because of the Reynolds

effect, so if one is not hand chucking, and using a short high start to fling his sailplane,wing area becomes crucial. The only limit on wingspan is the maintenance of lift at the

slower wings tip when engaged in turning flight (this can be improved upon by using anti-

stall strips (turbulators), washout, and/or a rectangular wing planform. The Ellipse wingplanform may be an efficient planform for cross-country work, however for attempting to

fly slow and spiral tight, the rectangular planform is the superior. Right off the bat we are

looking for the largest sailplane (for Reynoldss effect) with the least wing span (meaning alow aspect ratio wing with a parallel chord wing planform - within the limits of aspect ratio

efficiency); when we are talking short launch - with our eyes open to work the little HL

type of thermals more efficiently than the struggling little HLs (that are now common).

I think I must define the difference of Sailplane approaches; that are simply

expressed by soaring birds. The icon of soaring birds to Joe Wurts (for example) is the

Black Albatross; a very heavy bird that has a low CD to establish low sink at high

airspeeds. My icon on the other hand is the Fregata Magnificeno (man o war frigate); atropical bird that can lock its wings and soar for days over the islands. It too has a low CD,

however its light weight limits its airspeed. So following suite on this fact lets have atheoretical contest between Joe and myself of 2 mile cross country so as to imbed concept.

Joe does this feat in 15 minutes with his design concentrated upon flying a sailplane

dedicated to do work. I do the same task, but in 60 minutes. Joe believes he won; whereasI believe I won -- if the task was labeled duration!! Duration means staying up for the

longest time. Efficiency means doing a job in the least time. With this in mind, the

attributes necessary to accomplish Joes and my goals are totally different. The greatest

soaring creature on the planet is the Monarch butterfly breaking all kinds of records fordistance traveled. Yes, it even puts down the Black Albatross; however it cheats when it

uses the jet-stream!! Regardless, when the task is duration and one wants to use the small

thermals of the lower air, the design of the aircraft is distorted a bit closer to a dandelionsfluff, or parachute. Obviously the fluff has a bit of problem of landing close to launching,

or navigating from thermal to thermal, so compromises must be made.

Al Sugar 10-26-04