Hi everyone,

Slaerom built a fantastic 33% Piper, but was unable to upload photos.
So I’m posting the first few pics on his behalf.
This was his email to me.

Dear Sir,
It took me nearly 3 years to complete this. Unfortunately I have not yet been able to make a maiden flight because of the new restrictions in place. This can fly only at an airport. I am trying to work out a solution by talking to Authorities, if I succeed a maiden flight will happen and a video will be uploaded, if possible.
Regards
SL Mukherji

Moderator

A few more...

@slaerom

Please describe the build here, in stages from the beginning
I’ll try to attach appropriate photos from the ones you sent me.

Dear Iyer Sir,
Thank you for your support in uploading the pictures. I will start a serial description very shortly.
Regards

Guys,
I started this project in Aug 2017.
The piper was built on a Bob Nelitz plan imported from USA. Originally the plan is for building Piper J3 Cub with a 140in wingspan and 1/3 scale.
I used so called Indian Balsa and aero-ply sourced in bulk from Vortex RC for constructing the basic structure. Some carbon tubes, brass tubes, steel wire and metal, mostly aluminum was also used. Araldite and CA was used as adhesive on need base.
The fully loaded all-up weight with DLE 61cc engine and 23x6 carbon fiber prop. is approximately 8kg.
I made certain modifications in the build which are enlisted below ;
1. The Rudder and Elevator was redesigned to look like that of Piper Super Cub, with more roundish contours.
2. The tail plane assembly was redesigned to be detachable, for reducing fuselage length and making it convenient to transport.
3. The plan did not provide for flaps so that change was made and flaps were introduced on the wings.
4. The plan did not have a cowl build design so it was self designed and built out of Balsa with inner lining of glass fiber. Therefore the cowl looks a bit different.
To be continued.

Looks very good

Over the years I have collected a large number of machines and tools which were very useful for completing the job. The equipment and tools used were ;
-Dremel drill set
-Dremel Moto saw
-Dremel Work bench
-Standard Electric drill
-Work bench for electric drill
-Heat shrink iron
-Hot air blower
-Jig saw
-Hand drill
-Fret saw
-Hack saw
-Vice
-Files
-Soldering irons
-Other tools such as screwdrivers, spanners, hammer, pliers, drill bits, hole saw drill bits, taps, threading dies and clips/clamps etc.
To continue.......
 

I started constructing the wing first;
I had a computer table on which I laid a 6ft long 1in thick discarded plywood door which had a true surface.
On this I laid out half inch thick strawboard so that pins etc, could be easily pressed in to hold parts in place.
The wing plan sheet was laid over the strawboard and covered with a transparent polythene sheet so that the plan was safe from adhesives.
One rib template was used to trace and cut out 22 ribs and leading edge sub ribs out of 3mm balsa sheets which were clubbed together in set of 6 by piercing common pins to keep the sheets in place while cutting. Trailing edge of the ribs was cut to provide for Flaps and ailerons.
30mm wide and 5mm thick Chinese ply strips procured from a furniture shop was used as main spar and 15 mm wide strip of the same was used as trailing edge spar.
The wing tips were made out of dampened semicircular Chinese pine 10mm wide bidding procured from the same furniture shop.
All these parts were laid out on the plan and carefully glued in place to build the wing. The main spar extends out to meet the main spar of the other wing at the top of the cabin to be fastened together to keep the wings in place.
The constructed wing is strengthened by gluing cross trusses through the rib holes and by weaving two 10mm tapes passing over and below the mid section of alternate ribs in each wing. The trailing edge face of the wing where the hinged Flap and Aileron meet is concave while corresponding face of the Flap and Aileron is convex.
The hinges are made out of aluminum sheet cut to shape and fixed to 5x5mm pine wood square batons.
The trailing edge spar has a 10cm carbon tube fixed to it inside the wing to accommodate a tube extending at both ends of the fuselage wing shoulders for keeping both the wings in proper plain when assembled.
To be continued .........     


 

Hinges!

More hinges!

After covering leading edge of the wings, ailerons and flaps with 2mm balsa sheet the hinge members for holding the ailerons and flaps were glued into place on the trailing edge of the wings.
The hinge members for the two Sturts were angularly fastened with 2.5mm nuts and bolts on the main spar and trailing edge spar so as to be in line with the spars when fixed to the fuselage.
Two servo trays were fixed in each wing, one for the aileron and another for the flap. 
After giving the basic wing structures a smooth finish they were covered with heat shrink skin.
The ailerons and flaps were also covered with heat shrink skin.
Having completed the wing construction of the fuselage and tail plane was taken up.
To continue .....     

Wing structure and covering

After completing the wing, the layout plan was replaced by the fuselage layout plan and covered by transparent polythene sheet.
Both sides of the fuselage were built on the lay-out plan using 5mm carbon tubes for the frame.
The trusses were made out of 5x5mm balsa strips.
The two sides were tied to each other at the tail and separators were glued in place as shown in the plan.
This was followed by gluing the respective bulkheads cut out from 3mm aero-ply supported by a 5x5mm strip glued at the base.
The top ridge and shoulder ridge longerons of 5x5mm hard balsa were glued on the bulkheads from cabin top to appendage.
In the process a rib each was glued on both sides of the cabin top which will later be built into wing shoulders on either side.
The cabin window and wind shield frame was glued in place.
A Warren Truss structure was fixed on four corners of the cabin to meet at a point where the two wing spars will meet at the top of the cabin, the Warren Truss meeting point has a copper tube firmly tied and soldered to accept a 5mm steel rod which in turn inserts into similar copper tubes fixed at both ends of the wing main spars that enter through the cabin shoulders and meet at this point. This contraption helps in holding the wings together.
With the help of stringers two more ribs were fixed one each on either side of the existing ribs with a 10mm carbon tube inserted at the rear of the ribs to be flush with the tubes already inserted in both wings, which will allow insertion of a tube having OD equal to ID of the imbedded tubes and support rear end of the wing on each side of the shoulders.
The side walls from cabin rear to firewall was filled with 5mm balsa sheets and firewall made out of 6mm ordinary ply was glued in place.
Gussets were glued at meeting points of trusses to strengthen the joints.
The cabin shoulder ribs were covered with 2mm balsa sheet all round to make it firm enough to accept the wings on both sides.
Top of the nose section behind fire wall built in sections and covered with 2mm balsa sheet with one section removable for access inside.
Bottom of nose section of fuselage was covered with 3mm play with a provision for opening to reach inside.
Bottom of the cabin section/cabin floor was built out of 5mm ply secured with gussets to secure the landing gear.
Inner section of cabin are was lined with 2mm ply to cover the frame work and fillings.
Servo plates were fixed at suitable locations behind the cabin for the Elevator and Rudder servo with access openings provided.
To be continued .....
   

   

Fuselage

After completing the fuselage I proceeded to build the vertical stabilizer and the horizontal stabilizer with 5mm carbon tube, 5x5mm balsa batons, semi-circular Chinese pine bidding supported by gussets.
The Rudder and Elevator was hinged to the vertical stabilizer and horizontal stabilizer respectively with brass tube hinges made for the purpose.
Metal control hinges were soldered on brass tube and fixed to the carbon tube edge for free movement of the control surface.
The vertical stabilizer was built on to a shoe shaped base which could be screwed on to the upper side of the fuselage tail for assembly.
the horizontal stabilizer has a tubular hinge in the center of the straight end which is screwed on to the fuselage tail top before placing the vertical stabilizer structure, the leading end of the horizontal stabilizer has a flat extension which has holes for screws to adjust the angle of the stabilizer. 
the whole appendage system is strongly held in place with cable tied to vertical stabilizer, horizontal stabilizer and bottom of fuselage.
This was followed by building the folding cabin door and window.
The cabin door has a locking system with a realistic handle for holding it in place when in flight.
The folding window can be raised upwards and it is held in place under the wing with the help of a strong magnet.
The engine was fixed on the firewall to measure the length of the cowl.
The cowl was built out of 10mm balsa and 2mm balsa strips after assessing the length and providing for 30mm over lapping on nose.
The finished cowl was covered with glass fiber inside and outside to strengthen it.
After completing the fuselage in all respects it was covered with heat shrink skin, the same was used for covering the empennage.
The window sections were closed with clear plastic sheet and the same was used for the front wind shield and roof top.
The main landing gear was built out of 6mm brass tubes with 5mm carbon tube inserted to strengthen.
A telescopic shock absorber was built to hold the two landing gear sections in place by using cycle valve rubber tubing.
3mm hard aluminum plate was cut to size and bolted at the tip of either side landing gear to hold the wheel axel and wheels.
The part of landing gear fixed to fuselage floor has a parallel tube fixed to it to allow a 5mm steel rod threaded at both ends for bolting into flanges screwed on to the floor of the cabin, this allows the landing gear to expand outwards on each side for absorbing landing shock.
The tail wheel was fixed in place, engine fixed on firewall, cowl in place and 23x6 propeller tightened.
Lastly the sturts were built out of 12mm wide 4mm thick Chinese bidding ply. with one end having a fixed hinge for fastening under the wing and the other side having a threaded length of 3mm steel cycle spoke with loop at one end for length adjustment and bolting at the fuselage base.
The under wing sturt supports were built out of 3mm ply strips and covered.
25Kg Servos, electronics and fuel tank were put in place and other minor parts were added to improve aesthetics.
The Piper was finally ready for a maiden.
NOTE :- This thread is merely a brief description of how the bird was built, it is not a guide for building the model, as that would have run into a very lengthy and boring thread and would have consumed enormous space. However, if any one is interested in building a Bob Nelitz Piper J3, I would be glad to help wherever hurdles are faced. I am also open to suggestions for improvement.
A big THANK YOU to Iyer Sir for uploading pictures in this thread.
Regards and thanks for reading.