Archives for June 2017

Yard Ace Fuselage Construction

First side of the Yard Ace fuselage under construction.

First side of the Yard Ace fuselage under construction.  8″ ruler shows true size.

I am making good progress on a park flyer size variant of my Yard Ace design. All fuselage and wing structures are built and ready for covering.

As I discussed earlier it is fun to make a different size version of a previously flown model. Part of the process is incorporating design features as you do construction. In the case of the smaller Yard Ace I need to modify the sizes of the balsa wood used in the original version. The challenge is to ensure sufficient strength without adding too much weight.

One important change I had to make when constructing the fuselage is to increase the width slightly to accommodate the ParkZone electronics brick. This was discovered as I laid the electronics onto the fuselage plan top view.

I also had to consider adding a tray for the electronics as well as a custom balsa motor mount in the nose of the fuselage.

Both sides of the Yard Ace fuselage complete

Both sides of the Yard Ace fuselage complete

Adequate strength is important for these smaller models. I intend to use a lightweight iron-on plastic covering. These coverings are used by modelers everywhere, but they do shrink a lot and can induce warps should the structure be of insufficient strength. On the upside, a completed structure (wing, fuselage, etc.) can be much stronger once the covering is in place.

Yard Ace fuselage under construction over plans

Yard Ace fuselage under construction over plans

For the tail control surfaces I think that I will just cover one side to save a little weight and minimize inducing warps.

I know from experience that three ounces is about the upper model flight weight limit for the ParkZone prop and motor combination. A requirement for anyone constructing smaller models is the use of an accurate scale to actually weight the parts.

Yard Ace fuselage nearing completion

Yard Ace fuselage nearing completion

I purchased a digital scale on Amazon and it works great. Simply push a button and you get a numerical readout down to tenths of an ounce. If nothing else you can track the weight increase as you build and cover the various components.

Fokker Spin in flight

Fokker Spin in flight with spoke wheels

This attention to weight saved the day on my Fokker Spin model. For the initial test flights I had a pair of lightweight plastic wheels. The model flew well but the wheels looked horrible on this vintage flyer.

I had a perfect set of spoke wheels in my parts bin, but they certainly added weight. Luckily, the total of weight of the Spin with the new wheels was just a tad over three ounces. The model flew well, but the extra weight was certainly evident on model flight performance. The digital scale helped a lot with ensuring success with the heavier set of wheels.

 

Initial fit of ParkZone motor and electronic control brick

Initial fit of ParkZone motor and electronic control brick

Yard Ace Construction Begins

Yard Ace three channel RC plane front view

Original size Yard Ace three channel RC plane 

I have started construction on a smaller version of my Yard Ace model airplane design. This variant is sized to accommodate the ParkZone line of electric motor and an electronics brick that contains two linear servos, a receiver and and electronic speed control.

Initial fit of ParkZone motor and electronic control brick

Initial fit of ParkZone motor and electronic control brick

From experience I know that a final model weight of around three ounces works well for the ParkZone motor. As discussed in an earlier post, I enlarged a set of plans to a smaller size from the original Yard Ace to be a better fit for the ParkZone set up.

Fit check of paper wing rib template

Fit check of paper wing rib template

As you build a smaller variant of a model there is an aspect of “designing while you build”. The original wood sizes will no longer be accurate for the new model and must be adjusted accordingly. You will have to consider the need for a strong wing and fuselage structure yet at the same time working constantly to keep weight at a minimum.

Front view of completed Guillow Lancer

Guillow Lancer offers useful insights to wood size needed for smaller Yard Ace variant

In addition the use of lightweight iron-on plastic covering has shown to add a lot of overall strength to the covered structure.

As the target model weight will be under three ounces, the model does not require the robust structure typically used in a larger aircraft. Gaining experience building other examples of indoor models such as the Stevens Aero or Guillow line can give useful insights as to just what size of balsa wood is needed for a successful variant.

More to follow as i complete the wing and next tackle the fuselage!