Model Plane Size

 

Fokker Spin in flight

Fokker Spin in flight

The two decisions facing anyone designing an original radio control model airplane is figuring out what type of aircraft to build and the model plane size.

One of the enjoyable aspects of model airplane design work is the almost unlimited range of aircraft types you can capture in your model. Trainers, sport flyers or military subjects are all great candidates for a design project.

Once you are settled on the category of aircraft the next consideration is the model plane size you should target for the project. This is an important step as it will lead to selecting the correct sized motor and battery, proper building materials and understanding the type of flying planned for the aircraft.

Habit patterns

People tend to follow habit patterns and this is not a bad thing for model airplane design. Experience is useful when meeting the various challenges with creating an initial prototype of a flying aircraft. By having a starting set of design parameters for areas such as wing construction, fuselage fabrication and incidence settings you will be in good shape to ensure that your design will fly properly on its test flights.

ParkZone electronic speed control, dual servo and receiver brick

ParkZone electronic speed control, dual servo and receiver brick

In my case, I enjoy the smaller radio control models for indoor flight. I am very satisfied with the size and capabilities of the electronics offered by ParkZone for their micro flyers. The ParkZone “brick”, with its built in servos, receiver and electronic speed control works well for the smaller RC models.

ParkZone electronics

I am familiar with the power of this ParkZone combo based on my flying experiences with the ready to fly aircraft such as the ultra micro 4-Site and Extra 300. I have used these systems for several of my modeling projects and designs, to include the Finch, Fokker Spin and the RC conversion of the free flight Guillow Lancer kit. I have also built several kits that employ the ParkZone hardware to include the Pietenpol Air Camper, LiddleRod and the Hummingbird. Reviews of these kits and RC conversions will be added to the website soon.

1911 Fokker Spin front view showing dummy balsa engine cover

1911 Fokker Spin front view showing dummy balsa engine cover

The 1911 Fokker Spin is the largest model plane size I have flown with the ParkZone hardware. The Spin has a 28 inch wing span and weighs close to three ounces with the flight battery installed. This semi-scale aircraft handles exceptionally well and is, in my judgment, about the upper weight and size limit for the ParkZone power package.

With the Spin parameters in mind I set the size of my future planes to the rough dimensions of my earlier modeling projects using the ParkZone equipment. Sensible changes can be accommodated. For example, if the model has a minimal fuselage structure and corresponding lesser weight, such as with the Lancer, I can afford to make the model size a bit larger.

Incremental design

There is merit to this type of incremental approach to airplane design. This methodology is followed by manufacturers of full scale aircraft. There are so many aircraft design tasks that must be done right that it is crucial to minimize unknowns with any new design. This process can be seen in a wide range of aircraft families from the Boeing airliners to Cessna personal aircraft. From a design viewpoint there is not much difference from the two person Cessna 152 to the four place Cessna 172.

As a general rule larger RC models seem to fly better than smaller models. The penalty on flight performance for errors with a wing warp, incidence or trim setting can be harder to correct with the smaller models. Today’s RC pilots are accustomed to well flying micro models due to advanced CAD design and manufacturing techniques incorporated in the ready to fly category. Good handling models such as the ParkZone Cessna 210 or the Ember are recent entrants to the radio control scene. These petite models are just about too complex and precise to build from any sort of kit.

Guillow Lancer - free flight kit converted to radio control

Guillow Lancer – free flight kit converted to radio control

With these thoughts in mind I like to design my original RC models around the electronics and power system. Based on my positive experience with the Guillow Lancer the ParkZone hardware can easily handle a 24 inch wingspan model weighing tow ounces. As bigger models are easier to build and fly I decided to start with a baseline dimension of around 28 inches wingspan for a new design. Once the wingspan is set the remaining aircraft dimensions fall into place. I followed this approach with my design of the Fokker Spin.

Work area

Rear view of the Ares Tiger Moth 75

Rear view of the Ares Tiger Moth 75

Settling on the plane size also relates to your modeling work area and your flying venues. I construct model aircraft on my office desk due to lack of a garage workspace. Aircraft with wingspans less than 30 inches work well in these circumstances. I enjoy access to a large field house indoor flying area that is suitable for the flight speeds and maneuvering capabilities of the smaller models.

Over time you will accumulate a good understanding of what works and does not work in model plane design to anticipate and correct errors. A few of your aircraft design attempts will not work, such as with my kit bash of the Bleriot. The good news is that you will always benefit from in some manner from every attempt to design or modify an existing model plane layout. Anyone can design RC model planes. You just have to start and not be afraid to try!

Author: Gordon McKay