Buhl Pup

Front view of Buhl Pup showing radial engine

Front view of Buhl Pup showing radial engine

I added a page discussing the Buhl Pup sport aircraft and how this attractive aircraft would make an ideal candidate for a radio controlled model.

Designed in 1930 as a low cost, single pilot flyer the Pup is a distinctive aircraft with many features, such as the shoulder mounted wing and three cylinder radial engine, that make it a suitable candidate for drawing up a set of CAD plans.

Selecting a full scale aircraft to model is a personal choice. I always like to fly something a bit different from other aircraft on the club flight line, as I did with my Blackburn and Fokker Spin plans. I look forward to doing the same in the near future with an electric powered version of the Buhl Pup.

Indoor Turbine RC Model!

This post is a bit off topic for a website devoted to electric radio control flight. But below is an incredible video of a true RC model turbojet flying indoors!

This remarkable flight took place at the recent Model and Hobby Fair in Leipzig, Germany. The builders and pilots, Christian Huber and Jurgen Schonle, used a Diamond plan produced by Aviation Design.

Wingspan is 2.4 meters and the length is 3.1 meters. The model weighs about 5.5 lbs and uses eight ounces of fuel. Building materials were 6, 3 and 1.5 mm Depron. The engine is a T-20 Hummingbird Lambert.  The engine can operate at up to 235,000 rpm.

As you can see in the video the model handles very well. Keep in mind there is no prop wash over the control surfaces to aid in responsive flight controls with the turbine thrust exiting out the rear of the aircraft. Note the retractable gear and half flaps, needed for the slow flight in the indoor display area. The pilots report they only needed half throttle for the demo.

Also a wise move to have the fire department literally on scene should anything go amiss with the turbine engine. Amazing!


Full Size Electric Plane from a Model

Front view from airborne drone of Peter's test flight

Front view from airborne drone of Peter’s test flight

I added a page to the site today regarding a remarkable young man who designed a twin engine electric powered model biplane and flew it . . . then created via CAD a full size variant . . . built it in his basement with materials from Lowe’s . . . and then flew the aircraft himself.

The article also discusses the rapid advances of electric power in the full scale aviation world and how this parallels our experience with electric powered radio control model aircraft flight.

The video documentation is exceptionally well done, to include air-to-air drone shots of Peter’s initial flight. Folks are doing amazing things these days!

Workshop Update

Cleaned up workbench

Happy to report that my workshop is finally cleaned up and all of my modeling supplies are inventoried.

I did some repairs and adjustments to the Stevens Aero Buzzbomb. Main item was strengthening the landing gear installation. The original design had rubber bands holding the landing gear in a slot in the bottom of the fuselage.

Buzzbomb nylon landing gear straps

Buzzbomb nylon landing gear straps

I imagine this approach was brought over from the original free flight version of the airplane. The idea being that a free flight model could land anywhere after a flight and you wanted to ensure the landing great could easily break away without causing damage to the aircraft.

Older Spektrum receiver in Blackburn fuselage

Older Spektrum receiver in Blackburn fuselage

With the repeated landings of radio control flight this is not a good idea as the rubber bands are just not strong enough to keep the gear in place. The nylon brackets on either fuselage side should fix this problem nicely.

It is also time to resurrect my Blackburn design! I originally used nicad batteries in the original model. Plan now is to use my Thunderpower lipos. The two cell pack fits nicely in the battery area.

The receiver, however, is for the first generation of Spektrum transmitters. I needed a newer receiver that can bind to a DMS2 signal used by my current transmitter. The new receiver is on order. Once that is received and installed, I should be able to get this very nice flying model back in the air . . . calm winds only!

OuterZone Free Plans

OuterZone homepage showed latest plans added

OuterZone homepage showed latest plans added

I added a page today on a website offering over 8,700 free plans for vintage model aircraft. The site is OuterZone.

A wide range of model aircraft plans, drawn from 1913 to the 1970 are available for download. Models include free flight, radio control and control line aircraft.

The site offers plans that you will have to enlarge to full size. But these are complete model aircraft construction plans, not simply three views.

Back in this era of model aviation Almost Ready to Fly models did not exist. Everyone had to either build their own aircraft or acquire them at a swap meet. There was a thriving business with numerous aircraft plans offered for sale. As modelers could construct their planes from kits, most modelers could build from a set of plans as well.

The neat thing about these plans is the opportunity to build a model not usually seen at the flying field. Plans offer an easy route to make the necessary modifications for electric flight, as well as a change in the size of the model from the original.

All in all, another great way to explore the hobby of radio control model flight!


RCM Southern Gentleman plan, a perfect candidate for relaxing electric powered RC flight

RCM Southern Gentleman plan, a perfect candidate for relaxing electric powered RC flight

New Yard Ace Page

I added a page on my build of a park flyer sized version of my Yard Ace design. Very pleased with the outcome, see details here.

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

The Yard Ace is an easy to build RC model plane that makes for a perfect first build from a set of plans. In this case I demonstrated just how easy it can be to make a smaller version of a model from a set of plans. Same goes for making a larger version, should you wish.

The neat thing about being able to “design as you build” smaller or larger variants of a model from a set of plans is the large universe of new radio control model designs that become available to you.

In a future project I will do just this. First, select a plan of a model designed and built many years ago. Then rebuilt with today’s electric power systems and control electronics. And finally take this “new” model for a flight!

I enjoy Almost and Ready to Fly model aircraft as much as my fellow modelers. Still, it is nice to be able to build something on your own, and have a distinctive aircraft at your club flight line. More to follow!

Park Flyer Yard Ace Test Flight

View of the Parkzone powered Yard Ace on first test flight

View of the Parkzone powered Yard Ace on first test flight

I had a very successful test flight of my smaller version of the Yard Ace last night!

The total weight of the airplane came in at 2.3 ounces, well below my maximum target weight of three ounces (upper weight limit for the Parkzone motor). I had to add a bit of weight to the nose to provide the proper center of gravity balance.

Park flyer sized Yard Ace prior to test flight

Park flyer sized Yard Ace prior to test flight

The plane had plenty of power and flew right out of my hand. Control throw was good, although I think I’ll add either a bit more rudder area or throw to the final version. Handling in the air was smooth ad positive just like the larger version. There was no problem keeping the plane within the confines of my smaller test flight area.

Next steps are to draw up a set of CAD plans for this smaller variant with correct wood sizes as well as modified fuselage and wing layout. As you recall, I used the regular plan to construct this version and adapted structure as needed for the smaller prototype. For example, I’ll lengthen the nose a bit to help reduce the need for nose weight to keep the model within center of gravity limits.

I’ll include this new plan with the regular Yard Ace plan. I also intend to offer a video showing step-by-step how to draw the Yard Ace plan, now that my new Mac offers the capability of screen recording.

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!

Vintage Model Aircraft

Bleriot during a fly-by

Bleriot during a fly-by

I enjoy designing and building RC models based on aircraft from the first decade of flight. Sig offers a superb kit of the Demoiselle and I offer original designs of the 1909 Blackburn Monoplane and the Fokker Spin.

Many of these early flyers share flight characteristics that are not common with today’s more advanced aircraft. Issues such as adverse yaw and high-drag characteristics are a common theme.
Aerodynamic knowledge has advanced considerably since those pioneering days of flight a century ago. Engineers and pilots simply know a lot more about aviation and aircraft design.  This is reflected in today’s aircraft that fly in a predictable and safe manner.

Nose detail of the Blackburn RC model plane

Nose detail of the Blackburn RC model plane

When designing and flying model airplanes based on these early layouts, oftentimes the inherent adverse flight characteristics of the full scale variant can creep into the model’s flight behavior. RC pilots need to have an understanding of these issues in order to successfully fly model aircraft from this era.

I added a page discussing the issues of flying and designing vintage aircraft. This is based on my experiences with the Sig Demoiselle kit, as well as my designs of the Blackburn Monoplane and Fokker Spin.

In short, there are numerous ways to make a successful model of these aircraft that fly in a safe and predictable manner. Best of luck with your efforts regarding these true Pioneers of Flight.