Build the Park Flyer Yard Ace!

Mini-Yard Ace ready for flight. Note X-Acto knife for size comparison

Mini-Yard Ace ready for flight. Note X-Acto knife for size comparison

I have completed and flown a smaller “park flyer” version of my Yard Ace design. The original Yard Ace had a wingspan of 34 inches and weighed 9.5 ounces. I made this smaller, park-sized variant with a 24 inch wingspan and a target weight of under three ounces in order to use the ParkZone motor and lightweight electronics.

I am happy to report the Park Flyer Yard Ace test flight went very well. The weight came in at 2.4 ounces so the ParkZone motor offered plenty of thrust. I had to add a bit of weight to the nose section to obtain the correct center of gravity. Control throws seemed about right and the model handled smoothly in the air.

Detailed view of the Yard Ace nose section showing Parkzone motor and electronics brick

Detailed view of the Yard Ace nose section showing Parkzone motor and electronics brick

The smaller dimensions of this model required an adjustment on the sizes of wood employed. I knew that I had to keep the weight of each component as light as possible while ensuring enough strength in the finished model.

There is no clear method to do this, but rather to rely on experience to select the correct wood dimension. The main considerations being weight, adequate structural strength and the ability to withstand the application of iron-on coverings. It is very possible for iron-on coverings to actually damage the aircraft structure when aggressively shrunk.

Park flyer sized Yard Ace prior to test flight

Park flyer sized Yard Ace prior to test flight

Some considerations for this build of the park flyer Yard Ace. First, I knew from work converting Guillows models to R/C flight that 1/16 inch square balsa was surprisingly strong for wing spars. Thus, I did not require the full-depth forward and aft spars on the original plans.

The fuselage was not quite wide enough for the ParkZone electronics brick. This was easy to determine by laying the brick over the plans. I elected to place the electronics as far forward as able to help keep the center of gravity within limits.  

The use of 1/16 inch balsa glued together helped add strength to the fuselage’s wing support struts. I also used 1/16 inch square balsa for the tail surfaces, keeping in mind I would need to be careful applying the iron-on coverings.

Detailed view of the Mini_yard Ace nose section

Detailed view of the Mini_yard Ace nose section

As this initial look at a smaller version of the Yard Ace was designed more as a proof of concept that the targeted size and weight would work I did not spend a great deal of time with finishing details such as on the nose, cockpit and fuselage area.

Now that I know the model flies well I’ll draw up a set of plans on TurboCAD with the correct wood sizes such that no guess work is required to construct a version on your own.

Initial fit of ParkZone motor and electronic control brick

Initial fit of ParkZone motor and electronic control brick

Another advantage of drawing up a fresh set of plans is to incorporate changes learned in the test build. For example, with these smaller models there is a fair amount of weight gained in the tail area. I will make the nose moment a bit longer to offset this added weight to the tail during center of gravity balance, thus reducing the need for the extra nose weight.

This exercise in building a different sized radio control model airplane is a good demonstration on why it is so useful to be able to construct a model airplane from a set of plans.

Front view of the 24 inch wingspan version of the Yard Ace design

Front view of the 24 inch wingspan version of the Yard Ace design

With today’s graphics capability it is easy to enlarge a set of plans to any size desired. I use a flatbed scanner at FedEx Office. In the case of the Yard Ace I enlarged the 8.5” by 11” paper printout 240% to create a 75% version of the original.

The neat thing about being able envision and build a model at the smaller size is that there are literally thousands of older plans available through the internet that make excellent candidates for radio control variants.

View of the Parkzone powered Yard Ace on first test flight

View of the Parkzone powered Yard Ace on first test flight

Free flight models, for example, had to be designed right as they flew with no input from the pilot. Light weight was also mandated by the need to fly successfully with the common use of rubber band motors.

These well designed models are ideal candidates for conversion to radio control flight. All that is needed is the ability to make the necessary adaptations to the original plans to accommodate the electric motor, battery pack and electronics.

Many of the early radio control designs were essentially guided free flight models. By building again these aircraft in a size suitable to your flying area, a wide range of rarely seem models can once again be enjoyed by the pilots of today.

In particular I look forward to taking this same approach with a smaller version of my 1912 Blackburn Type D model. Should be a fun and interesting build!