1403

Item 1403

DESIGN: UniCopter ~ Pusher Prop - Variable Speed Rotors and Prop - 3-way Differential

Objective:

This page covers two designs of a 3-way differential for use on the linked page DESIGN: UniCopter ~ Pusher Prop - General - Variable Speed Rotors and Prop. The 50 / 50 torque split on the linked page is probably not ideal. The optimal torque split will probably be where only 33 %, or perhaps only 20% of the power, goes to the rotor during cruise.

It might be done by having a 3-way split where 33% goes to the interconnected rotors and 33% goes to each of two pusher propellers. Or where 33% goes to each of the rotors and 33% goes to a single pusher propeller. The concern is finding a design for differential gearing that can provided a 3-way power output. The two ideas below are such a design.

The input shaft to drive all 3 output shafts; where the sum of the rpm of the 3 output shafts is 3 times the rpm of the input shaft. In addition, the three output shafts may have separate and varying rpms.

Greater Torque Split Ratio between Rotors and Propeller(s):

Sketch of 3-way Differential: (torque split ~ 33/33/33)

The same as above except that the differential is replaced by a 3-way Differential and there are two propellers, each with their own Speed Controller etc.

For details see; DESIGN: UniCopter ~ Pusher Prop - General - 3-way Differential for Variable Speed Rotors and Props

Note that it might be more advantageous to go 3-way to one propeller and each rotor. Then synchronize rotors.

The two Speed Controllers can be used to apply yaw to the craft. (Not during autorotation)

To remove more power from the rotors during cruise, it might be possible for both of the above units to have separate coaxial counterrotating propellers. (power split ~ 20/20/20/20/20) Look into some time.

Sketch of 3-way Differentials:

Using 6 Differential Units:

This sketch also shows the Speed Controllers, propellers and rotors, in addition to the differential unit.

This arraignment could also be used for one propeller and two separate rotors. Will the fact that these rotors must be joined by a synchronization gear set cause a problem?

____________________________

Using 6 Planetary Gear Units:
This planetary gearing arraignment has not yet been check to see if it will work as desired. However, there is no reason to believe that it should not.

Notes on this sketch of planetary gear unit;

There are 6 planetary gear units.
The input shaft and gear drive the ring gears of 3 planetary units.
Each sun gear in the above 3 planetary units is directly coupled to a sun gear in each of the 3 remaining planetary units. Ideally, each pair of these interconnected planetary units are coaxial.
The planet gear retainer is connected to the planet gear retainer of a planetary unit that is not coaxial with it.
The ring gear of the each of the latter three planetary units is coupled to its own output shaft.

Notes Related to Both Gearing Methods:

The routing of the power in two methods above is identical. The difference is basically the style of gears used.

There are a lot of gears (approximately 40) and they must handle a reasonable amount of power and rotation.

This 3-way differential may be the place to implement some of the ratio difference between the rotors and the propellers. I don't think that this will work.

Temporary miscellaneous notes and replies related to 3+ differential gearing;

"I heard about some research a local company (that no longer exists) was doing years ago. They were looking into using a planetary configuration to achieve something like what you're asking for; 1 shaft in, four shafts out. The most detail I ever got was that they used a series of independent carriers which had a series of helical skew gears in each. They manufactured conveyor drives, what they needed a four shaft differential for and if they succeeded, I never found out in the end. An interesting proposal I thought, hope it gives you some ideas."

My thoughts; A four output drive should be quite easy to build. One differential feeds two sub-differentials.

Home Page | SynchroLite Home Page | UniCopter Home Page | Nemesis Home Page

Initially displayed: July 13, 2005 ~ Last Revised: July 8, 2007

The above utility invention is openly and publicly disclosed on the Internet to negate an entity from patenting it, to the exclusion of all others whom may wish to use it. ~ Reference patent law 35 U.S.C. 102 A person shall be entitled to a patent unless - (a) the invention was known ... by others in this country, ..., before the invention thereof by the applicant for patent.