Last time I reported on the some of the fun Randy Smithhisler, George Maiorana and I had flying electric airplanes at the Scale Masters 2000 competition at Wright-Patterson AFB, and promised to share some info on my Astro 010 powered Ryan ST. Here’s the story on that little job, along with some details on the Percival Mew Gull that I have alluded to in a few published comments over the past year or so as something of “mystery model”.

THAT LITTLE RYAN ST

The Ryan began life as a conversation between your writer and Philipp Gardemin, editor of the German magazine AUFWIND, about a review of the Astro 010 motor. As I explained last time, I felt that something more than just a tech review of the motor was in order, and decided to build a small scale model to be able to fly the motor and discuss it in the manner that makes the most sense to aeromodelers…as part of a flight report. As the great majority of modelers in the USA will never see an article published n a German magazine, I have chosen to paraphrase much of the AUFWIND material and present it to you here.

Picking an airplane was a choice based on finding a kit that would be readily available to potential builders, with a size and weight that would be appropriate for the little brushless motor. As the Micro 010 is supplied by Astro Flight in a direct drive configuration, it seemed best to choose a design that would be happy going fast rather than floating slowly across the tall grass behind a big, slow turning prop. The 30” span Ryan ST from Herr Engineering won out on all counts, helped along by the knowledge that along with the good ol’Piper J-3 and the P-51, this design is one of those special airplanes that most of us “just have to build, one of these days”. The kit is of course intended to produce a rubber powered free flight model, and some modification was in order to make it work as an electric powered R/C job. This turned out to be pretty straightforward, although I ended up having so much fun reliving building sessions of much younger days and trying things that I had only dreamed about back then that the Ryan project kept getting more and more involved.

I began by framing up the model essentially per the kit, adding only the extra leading and trailing edge material necessary to include the separate elevator and rudder that were not part of the original kit layout. The plan was that I would then cut into the wing center section to insert a carry-through spar reinforcement of 1/16” aircraft plywood that would extend one rib bay outboard of each landing gear strut location and carry the load of the airplane on the landing gear as well as adding structural strength to handle the increased flight loads resulting from the addition of electric power and R/C gear. In addition, I included 1/16” wire axles and LG strut reinforcements inserted up through the original laminated balsa landing gear fairings. I then cut the top portion of the fuselage from the rear cockpit forward loose and turned it into a big hatch to permit access to the motor battery without having to remove the wing. Well, the beefing up of the wing with a piece of plywood and the addition of a few pieces of light 1/16” balsa sheet to the center section to allow a removable wing to be handled without tearing up the covering every time worked as I planned, but when I looked at the fuselage with its open bay tissue covered structure, I began to imagine how nice it would look without all those flat tissue panels…remember that the ST had a beautiful monocoque aluminum skinned fuselage…and I lost all self control and did an old time sheet balsa inlay job! This is where you build a traditional bulkhead – and – stringer fuselage and then cut and fit a little piece of soft sheet balsa to fit into each of those little openings that were supposed to be tissue covered, then sand the whole thing smooth. If you use really light wood, keep the glue under control, and sand faithfully, it works well and looks great with an acceptable weight gain.

For the actual covering and finish I restocked my supply of “old time” stick and tissue building supplies by ordering some lightweight (“OO”) silkspan and colored domestic tissue along with some clear, non-tautening clear, and silver nitrate dope from Al Heinrich at Aerodyne, a supplier of classic rubber free flight modeling supplies down in southern California. (Call Al at 760-948-6334 and ask him to send you a catalog that will include more ideas for scale projects than you will ever be able to build!) The finished structure got a couple coats of thinned clear nitrate, then I covered everything with the light silkspan and followed that by double covering the flying surfaces with yellow tissue, adding classic old time cut-out tissue markings along the way. A couple coats of non-tautening clear nitrate sealed it all up. I airbrushed the fuselage and landing gear fairings with the silver dope after sealing them with a few coats of the classic talc and dope mixture and sanding it compulsively, then shot the whole thing with Testor’s “Dullcote”, which you find in the plastic model corner of the hobby shop. This stuff is compatible right over the dope finish. Although the kit makes provision for them, I chose to leave off the upper surface wing struts and the simulated landing and flying wires in the interests of practical everyday handling at the flying field. As I mentioned in the last installment, the color and marking scheme turn the model into a PT-16, which is the first US Army Air Corps version of the Ryan ST, preceding the much more numerous PT-22 that was characterized by an unfaired, landing gear mild wing sweep, and a Kinner radial engine. I think the photos say it all about this airplane…it’s one you just gotta’ build !

The motor turns out to be a little gem. Like everything else Astro makes, it is well designed and engineered. I have not had a lot of experience flying very small models, so I can’t make many meaningful comparisons, but I can state that the Micro 010 as installed in the 30” Herr Ryan conversion actually exceeded my expectations for flight performance. A brief resume’ of the factory specs provided with the motor is as follows: The Astro Model No. 801 “Mighty Micro” is a brushless motor supplied without a speed reduction device, intended for direct drive applications. Diameter is 0.975 “ and length is 0.9”, with a weight of 1.3 ounces. The BEC equipped control (on – off only, without proportional throttle, but with a soft-start feature) weighs only 0.25 ounce; as Astro says, “…this is quite a bit smaller that the Speed 280…that it is designed to replace. …(it) can handle over 25 watts, almost twice the power of a Speed 280.” Astro supplies the motor with an APC plastic 5.5 x 2.5 prop attached. I test flew the Ryan with this prop first, then tried an old (really old) Tornado Plasticote 6-2 that I found left over from my engine collecting days. Astro calls for 11,100 RPM at 3.5 amps on 8 volts using the APC prop; I tested and got 11,000 at 3.8 on a 7 cell NiCd pack. The 6x2 on the same pack ran at a bit over 10,000 RPM and 4.3 amps.

The airplane flies easily out of a hand launch…as yet I have not taken it to a site offering a smooth enough surface to allow a safe takeoff on those little wheels, although I expect that it will manage that just fine when the time comes. Flight speed is quite a bit faster than “scale”, which is to be expected for a model as small as this one, but the general appearance in flight is impressive. As there is no proportional throttle control with the Micro 010, the transition from powered flight to a glide is immediate, but the airplane handles it very smoothly, and the glide is quite gentle. I built pronounced washout into the wingtips, and it pays off in my being able to ease the model down for very gentle landings in the grass. Switching from the factory supplied APC prop to the thin, narrow blade Tornado 6-2 yields a more solid feel to the transition from handlaunch, a somewhat lower top speed, and better sustained climb, just as you would expect. I am reluctant to continue using the antique Tornado prop…once I find a current market replacement, I will be more comfortable with the airplane and get more time on it. Does anyone know where I can find wood or suitable light plastic 6x2 props?

THE MEW GULL

I made a brief reference to the Mew Gull project in my S&E Modeler column a while back, but was limited by space restrictions. Here is the full story on that airplane. About two years ago one of my friends here in the Northwest asked for my help in providing scale reference material for a ¼ scale Percival Mew Gull that he planned to build using Tom Hunt’s (ModelairTech) plans. I was immediately interested, as I had already begun collecting material on the Mew to the extent of having corresponded with Mr. Alex Henshaw in England, the former owner of Mew G-AEXF, who flew that airplane to a win in the 1938 King’s Cup Air Race and then after modifying it again, set a solo flight speed record from London to Cape Town, South Africa and back that has yet to be surpassed. I didn’t hear much about the project for a while until I got a call asking if I would be interested in buying it out. It turns out that several modelers were working together on it, and toward the end found themselves getting impatient, with the result that a rather simple plastic film cover and finish was put onto the basic airframe and a few flights made to prove that it would work. I got an explanation that the project was bigger than anyone had anticipated and that there wasn’t enough interest to support stripping off the covering and doing it over properly, and would I be interested in buying it all?

The result was that pity for the poor unloved airplane took over from good sense ( I had several other big projects to work on already), some green paper changed hands, and I took the various components of the Mew home. In short order I decided to strip it bare and to tear out about half of the fuselage structure as well in order to rebuild the model to represent Alex Henshaw’s 1938 King’s Cup version, which is noticeably different in structure and outline from the factory standard. About eight months later the model you see here emerged.

The primary structure is straight from Tom Hunt’s plans, but the cowl, landing gear fairings, and entire upper rear fuselage as well as the cockpit and canopy (hood, on a British aeroplane) are different. The structure is all balsa with plywood in high stress areas. The entire skin is sheet balsa replicating fabric bonded over plywood on the full scale airplane, the exception being the control surfaces, which are fabric covered using Stits Lite material. The entire balsa surface is covered with Dan Parsons’ 0.6 oz. fiberglass bonded with polyester resin, and this is finished , along with the fabric surfaces, with Stits products. The wheel fairings and cowl were built up from glass cloth and polyester on sacrificial male forms made of urethane foam, the unique spinner was made from glass and resin using a specially turned form, and the cockpit hood was drape molded from clear plastic on my own form. Power was an Aveox 1415-4Y motor matched to a ModelairTech belt drive, running on 28 3000 mAh Panasonic NiMH cells. This turns an 18-12 prop at just under 5000 RPM.

At this point the story becomes one of how all the little details can gang negatively, as it were, to keep a model from being really successful, and I am passing on the story to help you with your future projects. In short, the airplane flew OK before I did the rebuild, and was flyable afterwards as well, but the margin of performance I consider necessary to make a practical contest model wasn’t there. I ended up with a 14 pound airplane (not bad, considering the size and level of complexity) that would have flown really well except that it had less than 800 sq. in. of wing area, which resulted in a wing loading of about 40 oz. per sq. foot. Even so, the plane was flyable, but a max prop pitch speed of about 55 mph would not have been enough for the Mew ever to be really comfortable.

Sufficient change could have been made in the area of belt drive reduction ratio and increased voltage (higher cell count) to produce a more realistic speed range, but I chose to admit that I had allowed enthusiasm for an interesting “orphan” project to overcome better judgment, and when I was made an offer by a collector in the Midwest who has several of my other models in his impressive private museum, I accepted his very generous offer for the Mew and consigned her to a life of luxurious retirement. Could I have made the Mew fly really well? Probably, but I’m not sure well enough to be a serious competition airplane, and in any event the necessary time and effort are being better spent on new projects. I suspect that the Mew is one of those designs for which electric power as it is available for our use today can offer good performance for a simplified, very light replica or very short duration sprints for a “real” scale job, but not both at once.

OTHER PROJECTS

As I mentioned elsewhere, the Aeronca “K” and Miss Kitty projects are coming along well and you can look forward to flight reports for both airplanes before long. I am working on my friend Jerry Holcomb for photos and data and his beautiful Dewoitine 338 trimotor airliner as well as a really offbeat job he reports just having flight tested. I’d also like your input on a new project I have just taken on. I’m at the design study stage for a Spitfire…one that will be sized for motors in the 8-12 cell size range. This works out to a 1/8 scale model of around 55” span. I anticipate that it will be big enough for small retracts for those who choose to use them. The model will be accurate in cross section and outline, unlike most if not all of the Spitfires now on the market, but will be as straightforward in construction as I can make it, and the surface detail, interior, markings, etc., will be up to the builder. CAD plans will of course be available, along with a fiberglass cowl and molded canopy. I’d like to hear from those of you who might be interested in such a project via the email response page…click the “Contact Bob” key at the top of the page.

SPECIAL OFFER

This will interest those of you who have been thinking about getting a set of plans for one or another of the designs offered in the PLANS department. I have a limited supply of small monochrome (black and white) prints of lightplane illustrations that I did years ago for a promotion in cooperation with Model Builder Magazine. These measure 9” x 12” and will easily fit into standard off-the-shelf frames. Most are of a J-3 Cub as illustrated, but there a few of a PT-13, Aeronca Champ and Cessna 140 as well. I will include one of these FREE with each plan set sold as long as they last, and throw in a personalized autograph on the print as well. Interested?

Please don’t hesitate to send along reports and photos of YOUR electric powered scale project for us all to share here in SCALE VIEWS…jpg’s are fine, or you can send photo prints for me to scan. Snailmail goes to: Bob Benjamin FlightImages, 1222 26th Ave. NE, Olympia, WA 98506

Scale Views Volume 1