Manufacturing Plan & Processes

The goal in manufacturing was to construct the lightest weight aircraft while still maintaining structural integrity to withstand the flight loads. Different manufacturing techniques were analyzed for each of the aircraft components. The wing, tail, fuselage, empennage, and landing gear were studied thoroughly to determine the best construction. The schedule for manufacturing can be seen in fig

6.1 Manufacturing Processes Investigated

A variety of materials were investigated to optimize the strength and weight of the aircraft. Carbon fiber, balsa wood, birch, poplar plywood, spruce hardwood. The investigation into the use of carbon fiber led to the determination that its complexity to manufacture and necessary specialized tools would prove too difficult for our aircraft. Without these tools, the carbon fiber could potentially contain many flaws. Thus, Balsa wood was chosen as the principal material because of its low weight and ease of construction. Since balsa wood is a relatively weak material, other materials were also used to strengthen the structure in high stress areas.

6.1.1 Balsa Wood

Since weight is the driving factor in aircraft design. So, balsa wood, being light, soft & having high strength-to-weight ratio is easy to shape/cut & is commonly used in high performance model aircraft despite the fact that now a days advanced composite materials are easily available. Balsa wood is used for forming the frame of the aircraft.

6.1.2 Solid Foam:

Solid foam is extremely lightweight & can be shaped using a hot wire foam cutter. It is available in large sections. In most cases, the wing core is made up of this solid foam. This material is weak in tension but strong in compression and bending. The team has also used this solid foam as a wing core in the manufacturing of wing.

6.1.3 Carbon Fiber:

Carbon fiber being lightweight & very rigid possesses high tensile strength and high strength to weight ratio. It has very low thermal expansion and it can easily be turned to any desired shape like sheets of airplane etc. But it has certain limitations & the biggest one is its cost. It is far more expansive than balsa wood. Although it is very strong and light but you have to pay a big amount of money to be able to use it in your products. And once a carbon fiber structure is fractured, we cannot fix it like a balsawood and the structure is probably not strong enough anymore. And in most of the cases the structure has to be replaced by a new one. The team didn’t use this method due to the limited resources.

6.2 Manufacturing different components of Aircraft

6.2.1 Wing & Tail

The outer structure of wing is made up of balsa wood and thermacol sheet (foam cut by hot wire) is filled wire into the proper airfoil shape to keep the weight as low as possible. Thus, the wing can be regarded as Hollowed foam wing. Ribs and spars were discarded from this structure. The wing was constructed in one single piece & construction was done on a pin board so that all pieces could be precisely aligned and pinned in place to avoid wing warp. The tail configuration is conventional and all the components (horizontal stabilizer, vertical stabilizer, rudder and elevator) are made up of balsa wood.

6.2.2 Landing Gear:

The landing gear of the aircraft is attached to the vertical stringers. The landing gear uses carbon fiber skis and wheels. Generally, the landing gears are about 10 percent of the total weight of the airplane. Rigorous investigation was done to determine the optimal material for landing gear. Selecting the best combination of core and skin thickness could reduce the weight of the gear. Therefore, following materials were considered for manufacturing of landing gear:

Carbon fiber

Carbon fiber with balsa and foam

6.2.3 Fuselage:

Fuselage was created from Balsa & plywood frame. It was then skinned to give the desired shape. The external walls of fuselage were made up of plywood in order to resist large stress and its thickness is 3 mm. Fuselage base is also made up of 3 mm thick plywood with landing gear mounted. Inner fuselage walls are also 3 mm thick and made up of both balsa and plywood (to resist large stresses).

6.2.4 Cost and Money

The overall cost of this entire project is around Rs 50,000 which includes the cost of 6-channel transmitter receiver set.