"Propfan Engine", "Open Rotor Engine" and "Ultra High Bypass Engine" was developed as "Advanced Turboprop Engine" to get the high flying speed obtaining about the same fuel consumption as "Turboprop Engine.
There are several type of engines as follows;
"Puller (Retract) type" - Contra (Counter)-Rotating Propeller (Fan) with gearbox is located at front like as common turboprop.
"Pusher (Un-Ducted Fan) type” - Contra-Rotating Fan without gearbox is located at rear.
But the development of these type engine seems interrupted according to the noise problem, etc. except one company in France.
The contra-rotating power turbine mechanism with sweep-back angle fan blades of "Pusher Type" aroused my interest very much.
Then I tried to make a desktop model, but it was very difficult to get smooth contra-rotation.
But my target model was able to be eventually made as result of several trial and error.
A. Features of this model are;
1. Contra-Rotating Fan (PT: Power Turbine) can be turned by a home type vacuum cleaner.
2. Engine (Gas-Generator) cutaway model is inside of Cowling, but it is not rotated by the air.
3. Entire engine cowling with removable cover.
B. Assembly Manual (PDF format, total 19 pages)
The detail assembly manual including "Parts-List", "After printing treatment" and "Assembly procedure" are prepared based on "Standard Skill (Filing, Drilling, Tapping and painting)".
The important adjustment of axial clearance is described in the manual as marked ●.
C. General Notes
1. Bearing Selection
Bearings are very important parts to get smooth rotation. This model is based on using with following size "Open type" ball bearings because of low friction.
ID x OD x W = ① 7 x13 x 3 ② 9x17x4 ③ 17x30x7 (2pcs)
[CAUTION]: "Shield type" ball bearing is thicker, then rubbing problem may occur.
2. For M1.4 Screw
No need “Tapping”. Drill with φ1.0 drill then direct screw-in.
3. STL file name
“ws” of last 2 digits means “With Support” special designed.
Download files includes;
-files: STL Files (48 items)
-PDF(Zip) File: Assembly Manual
-images: Assembly Photos
Purchase Parts Information;
See Assembly Manual
See Assembly Manual
Micro screws M1.4x3.5L - Appox. 30 ea - Direct screw-in to 1 mm dia hole (No nut)
Screws M2 x ** - See Assembly Manual
- Standard Skill (such as Drilling, Tapping, Filing, Tightening, Painting and Gluing etc) is needed and perseverance too.
- Others: See Assembly Manual
Total Net Print Time: Approx. 80HR
- (Estimated as case of PLA, 0.4mm Nozzle, 0.2mm Layer Height, 40% infill and No raft and support)
Note: When at actual print, each parameter may be adjusted by your experience.