Turbine Engine Progress Report #1

We have never seen anything create the excitement generated by the announcement that the HELICYCLE© is turbine powered and when the new prospect finds out how low the price is they are just flabbergasted.  The idea of using the HELICYCLE as a daily commuter now begins to sound like reality.

We have chosen Sept. 1, 2002 as the official starting date for the first six-month production run of the Solar T62 Engines.  We chose this date even though we started engineering on the new gear box about five weeks ago, because as you can see from the photos, the generator sets have just now arrived at our plant. 

A number of questions have been asked concerning this power plant, however we will only comment in detail on one of them.  This concerns the engine testing aspect and what Eagle R & D plans in this regard.  We need to point out first that the turbine engine hardware has logged thousands of hours on hundreds of generator sets.  What Eagle is doing is replacing the cumbersome gear cases with much lighter weight castings and further reducing the 6000 out put rpm.  We do not need long term testing on the physical castings, because the gear separation loads are well known and the casting webbing is sufficiently over designed to handle them forever.  The real problem is holding the machining tolerances.  These include bearing fits and positioning.  Our CNC equipment readily holds .0005 positioning and the gear lash will be checked on each gear set in each case on final assembly.

The spur gear set we are adding for the final reduction is very straightforward from both design and construction stand points, (the gears will carry the maximum out put of this engine, twice what we need for the HELICYCLE.)  These are not automotive gears, but ground aircraft quality AGMA 12 gears designed and stress analyzed on the latest generation Gleason Design and gear stress soft ware.  Automotive gears are of AGMA 8 quality and a few modifiers of the T-62 have used them with success in the past, but they don’t meet Eagle’s standard of quality.  We do not believe it will require long term testing to confirm the viability of this gear set.

The purpose of the modifications we are making to the engine is of course to reduce weight, not to reengineer the power plant design.  We will however test all changes, on our dynamometer, prior to shipment. 

Just a brief comment on installation: installing the engine in the airframe is a simple matter and it won’t be difficult for the builder to hook up the power plant electrical system.  The electric clutch mounts with three bolts, however wiring it may take a little time since there is an engage / disengage switch, a red and green light and two push buttons in the circuitry.  The two buttons allow for very precise movement and rapid travel.  It’s a really cool system and the ball screw unit is as powerful as it is light weight.

This first progress report is a little premature, however quite a lot has already been accomplished.  We have completed all the engineering design on the gear case, designed and stressed the reduction spur gears, designed the oil scavenge pump and dry sump system.  We’ve worked out the starting and alternator systems and have many parts on order.  Many special tools have been built which are mandatory for correctly disassembling the turbine.  Good progress has been made on the casting patterns for the gear box as can be seen in the photos.  We are in the process of purchasing the non-destructive testing equipment for inspecting the turbine components.  The high speed wheel balancing equipment will be in house soon, as well.


Photo Captions

#1. The first load of generator sets arrive.

#2. Removing the turbine unit from the set.

#3. The turbine is less than 12" in diameter and weighs only 45 lbs. ,but the gear box it’s mated to is large and very heavy.  It was obviously never meant to get off the ground.

#4. There is a day and night comparison both in weight and size, between the old and new casings.  The circle with the “X”
in it is the position of the tail rotor drive shaft.  From this it’s easyto visualize how high the engine centerline will be in the air frame. Keeping the centerline high, reduces drag.  There is also 20 lbs. of forward thrust added from the turbine exhaust.

#5. Notice the split lines which delineate the three separate patterns.  For those not familiar with the art of pattern making, we should probably point out that these patterns have been made in the finest traditional turbine gear case style.

A.  The webbing alone supports the gear separation loads so the casing needs only to hold the oil.  The wall thickness is therefore thin and weight saving.

B.  Special attention is paid to all fillet radiuses to prevent shrinkage.

C.  The casting mating surfaces are just wide enough for an “O”-ring seal and taper away immediately to the thin wall protocol.

D.  Through bolts and nuts are not used, a lot of weight is added this way.  Instead, socket head cap screws secure into helicoil inserts.  This also cuts down bolt boss size without sacrificing clamping force. These and other measures cut casting weights by over half.

#6. The fuel system and starter accessories are tucked in close to the turbine housing diameter without excessively hampering compressor air flow.  A new adaptor plate is being made for the fuel pump, which makes it far easier to remove and/or install it.  (This area is a real bear to work on, on the original case.)

#7. The drive and driven pulleys are both just over 8" in diameter, so this photo readily shows the much reduced gear box profile.  There is a neat surprise stowed behind the drive pulley, but we’ll keep it a secret for now.

 

Stay tuned for further updates as we find ourselves slipping ever deeper into the blissful haze of Kerosene Fever.

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