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Aug 16, 2006, 07:44 AM
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Build Log

Sports Aviation Ryan STA 40 ARF Build

(1) Preliminary Notes and Thoughts:
Normally, I am not an ARF assembler, but I wanted a new plane quickly to get my power system back in the air. I hate to see Li-Po batteries just sitting around “aging.”

Note 1 – Supplier Wing Area Wrong: I had dismissed this plane several times because of the 288 wing area given on the Hobby People site. After the untimely demise of my Sports Aviation Sport Stik 40 ARF Low Wing Aircraft conversion ( due to a faulty connection between the switch harness and receiver battery, I had a power system to get back into use soon, as I didn’t want the Li-Po batteries just sitting around “dying!” I have two packs for this system.

I had just finished an article for the September 2006 Ampeer ( where I have made some specific recommendations for a similar power system, and this plane didn’t seem to work because of that “tiny” wing area for an up to a “46” glow engine.

I have been doing a lot of unit conversions recently from metric to Imperial measures and visa versa. I noticed that the wing area numbers did not match up; 31.5dm^2 = 488.25 and 288 = 18.58dm^2. Global ( is the importer of Sports Aviation ARF planes and their site ( also shows the same data for the Ryan STA as the Hobby People site. This was not surprising since it appears that Hobby People and Global are “related” as they both are at about the same physical location in Fountain Valley, CA according to what I could find on the Internet.

Figuring that something was “wrong” with the wing area, I downloaded the construction manual for the Ryan STA ( The manual gives the wing area as 488 (31.5dm^2). That made sense for the stated wing loadings.

My better guess at the true wing area is: 465 (30.0dm^2) The chord is 8.625 inches and the 1/2 span is 28.3125. If the panel were a true rectangle, then the 1/2 wing area would be 244.2 and the wing area would be 488.4, but it is not a rectangle. To allow for “missing area” I multiplied 488.4 times 0.95 = 463.98 and rounded up to 465 for my purposes. Once I had the wing area, I changed the target weights and loading below using 465 instead of 488
This could still be an overestimate as using the scale, noted below, of 1/6.3, the wing area would be 450

Note 2 - Weight & Wing Loading Targets:
Since this is to be a sport scale type aircraft, my target cubic wing loading (CWL) is 10 oz./cu.ft. (10Kg/m^3) yielding a ready to fly (RTF) weight of 58 oz. (1.64Kg). For my flying ability and the way that I want to fly this plane, what I call its task, my maximum acceptable CWL is 13 oz./cu.ft. yielding an RTF weight of 75.4 oz. (2.14Kg).

For those of you who prefer using wing loading in square foot units that would be 18 oz./sq.ft. to 23.3 oz./sq.ft.

If you would like to learn more about cubic wing loading, I have an article here:

The supplier gives a RTF weight of 60 oz. (1.70Kg) – 68 oz. (1.93Kg) with a wing loading of 17 oz./sq.ft. to 20 oz./sq.ft. I have collected a lot of data on model aircraft over the years and have found that the completed airframe weight (CAW), for a glow-powered plane, is about 60% of the highest supplier weight. Therefore, the completed airframe weight, with no power system or onboard radio components, “could” weigh about 41 oz. Once I have the kit in hand, it can be verified.

Preliminary weights: 41 oz. (1.16Kg) (airframe), motor & battery 24 oz. (679.3g) and 8.06 oz. (228.6g) (onboard radio components) = 73 oz./4.56 lb. (2.070Kg). The input watts for the power system are about 460, which means about 100 watts in per pound. It is looking good on paper.
(Note - 8/25/06: The motor & battery and onboard radio components weights were reflective of what I used during this preliminary data stage. The actual measured data is listed correctly below.)

August 10 – searched the Internet for photos and information on the Military version of the Ryan STA known as the YPT-16. good basic info shows right side of cowl with exhaust exits and cowl openings
There are a few more sites with photos and information, but right side photos are hard to come by. There seem to be more RC versions of this plane on the Internet than full-scale.

Note 3 – Scale ?:
The wing area of the full-scale STA appears to be 124 sq.ft. or 17856, which means that this is about a 1/6 scale model based on a 488 wing area on the model, but the length and wing span indicate a 1:6.3 scale.

Aug. 13 – Went through construction manual again to become familiar with the assembly process and note possible modifications for the e-powered version.
Aug. 14 – Shaft and prop adapter arrived from BP Hobbies (
Shaft was bent in demise of Sport Stik and prop adapter could not be removed.
Replaced shaft (Ended up being a four-hour job. If anything could go wrong, it did!), tested motor. All seems well.
Aug. 15 – Went through downloaded manual again and made sure I had all the tools and items needed to start work on the plane.
Aug. 16 – According to UPS tracking, the plane and other parts are due to arrive today.
Last edited by Ken Myers; Aug 25, 2006 at 09:22 AM. Reason: Provided URL to September Ampeer
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Aug 16, 2006, 07:45 AM
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(2) The Kit:

Sports Aviation Ryan STA 40 ARF $129.99

Kit and other items ordered from Hobby People arrived at Noon, Aug. 16, 2006. Initial inspection show no shipping damage.

All of the following weights are out of the box weights with no trimming on plastic parts. All weighing was done using grams and then converted to ounces (oz.).

There doesn’t appear to be shear webbing in the wing. The top spar sets down in the rib, not going across the top. The two middle CA aileron hinges were almost pushed entirely into the wing and were difficult to get out. Both wing panels appear flat when laid bottom to bottom and almost a perfect match. The airfoil is unknown but a “typical” flat bottom, something like a Clark “Y”, but not a true Clark “Y”. It is relatively thin.
(Note – 08/25/06: The spar actually turned out to be made of 3/16”x1” balsa with the ribs fitting down over the spar. That is why I couldn’t feel any top spar.)

Right wing panel: 150.0g
Left wing panel: 152.3g
Wing joiner: 11.7g
Spat #1: 19.1g
Spat#2: 21.5g
Main gear #1: 21.4g
Main gear #2: 21.2g
3-inch (76 mm) sponge wheel #1: 18.5g (This is a good size wheel and bodes well for flying off of grass)
3-inch (76 mm) sponge wheel #2: 19.0g (Still worried about the spats though)
Landing gear hardware: 20.1g
Wing strut hardware, fairings & rigging lines: 6.7g
Wing strut #1: 8.7g
Wing strut #2: 8.8g
Control rods, etc for the ailerons: 14.1g
*Plywood for mounts for smaller servos for ailerons: 3.4g
*Plywood and balsa used for the fairing/spat attachments: 7.6g
Total wing weight with no glue: 17.8 oz. (504.1g)

Looks good with just a very, very few small marks/dings in the balsa and the covering is nicely done. The black striping tape for use on the windscreens is included in the kit. I had missed that.

Main fuselage component: 255g
Fiberglass Cowl: 50.8g (nicely done and no hole on right side for a glow exhaust!)
Untrimmed plastic parts:
Headrest: 3.4g
Cockpit #1: 3.8g
Cockpit #2: 4.1g
Windscreen #1: 6.5g
Windscreen#2: 6.8g
Tail-wheel bracket, wheel and hardware: 23.0g
Elevator push rod: 19.5g
All control hardware for fuselage: 22.9g (includes horns, etc. that will be on the elevator and rudder.)
*Battery tray, Velcro and cross braces for tray: 24.3g

Total fuselage weight with no glue: 14.8 oz. (420.1g)

Vertical stab: 16.9g (solid wood)
Rudder: 19.3g (solid wood with lightening holes)
Horizontal stab: 34.2g (built-up)
Elevator 1/2 #1: 6.6g (solid wood with lightening holes)
Elevator 1/2 #2: 6.7g (solid wood with lightening holes)
Total tail weight with no glue: 2.95 oz. (83.7g)

Total Unglued Weight: 35.6 oz. (1007.9g)
Even with glue, it is going to come out several ounces lighter than what I based my preliminary data on.
The motor and battery mounting components will add a bit more weight. I’ll note it when I get to it.

General notes:
The packages of parts had a “strange” smell to them and left a taste that I can’t get out of my mouth.
The unknown covering looks good on all areas. It looks like no touch up with the iron is necessary at this point.
The glow spinner, provided in the kit, that I won’t be using, is yellow, not red. I did not weigh the tank, prop or motor mount components provided in the kit.
Last edited by Ken Myers; Aug 25, 2006 at 09:29 AM. Reason: Corrected some errors
Aug 16, 2006, 07:45 AM
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(3) The Assembly and Modifications

Step 1: Mounting the Motor
I tried various ideas for getting the motor into the proper position to match the cowl opening. I finally used the horizontal and vertical lines crossing the firewall completely (Shown in attachment below). The vertical line is centered on the firewall and the horizontal line is 1 11/32 in. (34mm) from the top of the firewall. I carefully removed the installed blind nuts. I then eyeballed the motor with the mount attached, centering it using the horizontal and vertical lines and marked the holes for the new 6-32 blind nuts. I drilled pilot holes and then the holes for the 6-32 blind nuts.
I mounted the motor and spacers, attached the cowl with tape and found that the centering was okay, but the spacers need to be cut down 1/4 in. (6.5mm)

Step 2: Battery Tray & ESC placement (August 17, 2006)
I used the cutouts in the first and second formers to set the depth of the 1/4”x3/4”x3” inch balsa cross braces that hold the battery tray. They are 1 3/4” down (which is toward the top of the fuselage) from the straight top edge (which is really the bottom when the fuselage is upright) of the cutouts. The 1/8”x2”x5 7/8” plywood battery tray with Velcro and a Velcro seatbelt is glued on top of the cross braces. A cross brace was also glued to the partial former just in front of the first cockpit and the battery tray. Two more holes were created using a drill and Dremel sanding barrel for airflow in former F1 and also a slot for the insertion of the ESC. A slot was also formed in former F2 for the ESC wires to pass through. All of the holes were done BEFORE gluing in the battery tray. The completed tray was epoxied to the cross braces and the firewall.

Finally Getting Started with the Assembly Manual!
The first thing to do is to install the aileron servos. I made sub-pieces and cover pieces from 1/8" plywood to shorten the hole in the precut aileron servo mount. The sub-pieces were put into place using slow cure CA and then the cover pieces were epoxied in with 30-minute epoxy. Balsa sidepieces were made to fill the gap in the installed servo mount to reduce the size of the hole and then covered with some yellow iron on covering.
Even the first step took longer! ;-)

It is mid-afternoon on the second day of the build and the wings are just being joined. Of course it would be a lot shorter process if the whole thing weren’t being documented. Also, figuring out the battery tray and motor mount took time that you won’t need to use, since the notes are here on how to do it.

The directions were followed for joining the wing panels. Glued in the horizontal stabilizer. While waiting for the glue to dry on the wing joint, trimmed all the plastic parts and put the black striping tape on the windscreens. Used a Dremel barrel sander to put the “scale” openings in the cowl.
Called it a day.

The First Glitch:
Early morning, August 18, 2006
Epoxied the vertical stabilizer in place. Hinged the ailerons. Decided to attach the landing gear while waiting for the epoxy to dry. There were only 7 landing gear straps and 13 screws for the gear. Found another strap and screws in my supplies. Put a hole in bottom of wing covering just outside the landing gear block. The landing gear blocks are not “wide” enough for the supplied landing gear straps to go across parallel to the chord of the wing.

I have to go to town today, a thirty-minute drive one way, so I’ll get some replacement straps at the hobby shop in Port Huron. The rest of the build is going well to this point.

After returning from the hobby shop, the landing gear was finally attached. While I was attaching the gear legs, I realized that my gear don’t match the photo in the instruction manual. To use the gear I have, I could have used 6 straps, two in front and one in the back, which may have been the way to do it. The attachment photo shows what I did.

The landing gear continued to be tedious. There were a couple of small, black plastic tubes that I reasoned to be axle spacers. It said nothing about them in the manual. The inside diameter of the black tubes were too big. I shimmed them with some aluminum tube, but the tubes were too long to allow the wheel to go inside the spat. Half that length would have been about right. Out of frustration, I used some wheel collars that I had.

After the landing gear was FINALLY attached and the spats installed, I mounted the motor and screwed on the cowl. It’s looking like an airplane now.

Did I mention that the landing gear assembly was way too difficult and that the instructions in this area left a lot to be desired? Hot, sweaty and taking a break now. The best part of dong the landing gear was the motorcycle ride to Port Huron and back. The landing gear, fiddly, fiddly, fiddly!

Radio Installation Problem: (August 19, 2006)
The morning assembly started at 6:30 a.m. I cut off the motor mounting bolts to the correct length. I added some plywood cross pieces to shorten up the servo mount for the Hitec HS-225 servo to be used on the elevator. The problems started when I tried screwing the clevises onto the elevator put rod. I like to do this so that the clevises are not “virgin” when screwing them on after the push rod installation. It was difficult and took a while as the two rods on the elevator pushrod rear wanted to wrap around each other as I was screwing on the clevises. The next 1.5 hours, yes, that’s right, one and a half hours was spent trying to get the elevator control rod in and lined up with no success.

By carefully looking at the photo in the manual, and in pure frustration, I extended the elevator pushrod slots on each side of the fuselage by 1 inch (25.4mm). That seemed to solve the problem. The elevator was finally installed and working by 11:00 a.m. The install started at about 7:00 a.m. Four hours is way too long for installing the elevator pushrod!

Rudder Pull-Pull installation & a new problem: August 20, 2006
I started the day with a new problem. I had done some research at RC Universe last night and found this troubling thread.

It appears that my doubts about the wing construction are well founded!

I started the rudder pull-pull installation at 6:30 a.m. and completed it at 10:45 a.m. The next step would be to install the aileron pushrods, but…

I have decided to remove the covering from the bottom of the wing and “fix” the landing gear and spar. I am also going to do the spat attachment “fix” by Richard Say, that I found in the same thread at RC Universe.

This is turning into much more of a project than I anticipated!

First I removed the fairing/spat from each landing gear assembly and cut a 1/8” plywood triangular piece to go in the center of the wire landing gear triangle and then the two 1/8” balsa triangular pieces to go on each side of the leg, per Dick Say’s modified attachment in the RC Universe thread mentioned above. Next I removed the covering from the bottom right side of the wing and found the spar to be 3/16” by 1” balsa with the grain running span wise. I faced the spar with 1/16” shear webs on each side except for the landing gear block bay, servo bay and last bay I opened up. I also reinforced the landing blocks with 1/8” plywood. This added about 0.71oz. (20g) in weight to the wing not including the weight of the glue.

The whole day seemed like I was moving backwards. Only time will tell if all this extra work will pay off.

I added a 1/16”x1”x 2” plywood plate over the single wing hold down bolt area of the wing.

Monday, August 21, 2006:
Worked all morning, 4 hours on the wing strut attachment. It was another fiddly bit.
Into Port Huron; Jo Ann for jewelry crimps and something to use for a turn buckle, hobby shop, Lowes, ACE and ACO hardwares for paint and got everything needed.

After lunch the bottom of the wing was covered with Sig AeroKote Cub yellow. The color doesn’t match. This is the first time I had used this covering material, and there is NOTHING to recommend about it. The graphics were recreated using black contact paper picked up at the hardware store in Crowell. This work was completed by suppertime and I was right back where I started from on the wing assembly, two days later! Hope it was worth it.

Tuesday, August 22, 2006:
Reinstalled the wire landing gear to locate the landing gear strap holes. Glued on the balsa and plywood “sandwich” to the landing gear wire and removed the landing gear units to dry before drilling holes for the fairing attachment. Started the aileron hookups. Went into Croswell to get a better color of paint and possibly something that will work better for the rigging turnbuckles.

Made up a test fit and painting board for the landing gear and fairing/spats. Painted the fairing/spats and wing braces.

Finished the aileron controls hook up. Glued on the headrest and windscreens. Used the heat gun on the wing again. Put the landing gear on. I was able to move the outer landing gear straps closer to the now painted fairing/spat on each wing. Put on the wing braces and rigging. Used clear silicon around the spat fairings where they meet the wings. Used clear silicon to “glue” the wing brace fairings to the fuselage and wing and removed and reglued the front windscreen, as it was cocked to one side.

There is still a lot to do, but it is looking like a plane now.

Not feeling like “working” on this plane anymore today, I carefully measured the wing area: 461.7 (29.8dm^2). The area near the tip was traced onto paper with 1-inch grids. The partial areas were cut from the paper and joined to make 1-inch squares. The known rectangular area of 19.75” x 8.625 (170.34375) was added to the 50 whole square inches near the tip and the 10.5 that were “extra” at the tip for 230.84375 for half the wing times two equals 461.6875 Now that question is answered.

Wednesday, August 23, 2006
The receiver battery, switch harness and receiver were installed taking the center of gravity into consideration.
Triangle stock was added where the firewall extension exits F1. 0.22 in. (6mm) aluminum tubing was cut to create the exhaust pipes glued to the cowl using silicone. The aluminum exhaust pipes were added to the cowl. All of the control throws were set per the manual.
I did a range check. Everything checked out okay.
I added a make/break connector for the Li-Po battery in the front cockpit. It takes a long time to change the large battery that I am using in this project. Because of it size, it has to go in through the wing area. Also, and very importantly, the battery can be in place and not connected until it is time for a flight. This connector is a very important safety feature. The rear cockpit insert will not be used while flying and the open rear cockpit will be the air exit.
If everything goes well, pilot bust figures will be added and the rear insert opened in front of and behind the pilot bust figure.
Masking tape was used to cover some of the Velcro on the front of the battery to allow it to slide in and out of its position more easily. The number graphics were cut out of black contact paper and applied to the model. Photos were taken.
The plane is now flight worthy and it’s mid-afternoon Wednesday.

August 28, 2006 Getting the plane into better trim.

Thrust Adjustment: I carefully checked the motor thrust using the string method, yardstick method and a building triangle. There was no thrust offset detected either left or right. I added 1mm thick washers between the left side standoff spacers and the firewall, but that “appeared” to give too much right thrust. The prop adapter rubbed on the cowling, so they were moved between the motor mount and standoff spacers to give less right thrust. The triangle placed against the firewall indicated there was some down thrust, although I did not measure it in degrees. I also added a sandpaper disk to the prop adapter plate to make tightening the prop easier.

Excessive Right Trim Adjustment: First I used a Robart Incidence meter on each wing panel near the root and tip to determine if I had inadvertently ironed a twist into the wing when putting on the new bottom covering and tightening the top covering. I measured, measured and measured again, over and over, and I could find no twist in either panel.
Next, I checked the lateral balance and added 7g of weight to the right wing tip. Hardly much at all, and probably not the major cause of the excessive right trim need to fly the plane level.
Finally, I found the left elevator half to be 3/16” higher than the right elevator half. This may very well be the major cause for the excessive right trim.
The elevator halves were very, very carefully adjusted so that the transmitter trim could be set back to neutral.
The rudder cables were tightened and the rudder adjusted so that the trim on the transmitter could be set to neutral.

Poor Roll adjustment: Differential was added to the ailerons and the throw increased to try and get a better roll rate. The recommended 3/8” up and down produced an EXTREMELY slow roll to inverted and quick roll out of the inverted. The throws are now 5/8” up and 3/8” down on the ailerons.

I double checked the center of gravity and found it to be 2.75” back from the leading edge, which is what I had set it at when balancing the plane originally. I need to do the flying/diving CG check. That is the only good way to know if the CG is correct.

August 30, 2006 Getting the plane into better trim, sealing the gaps.
Since I had the time, I decided to seal the aileron and elevator hinge gaps with some yellow iron on TowerKote covering. All of the planes I fly use “S” shaped “Monokote” type hinges that are, by the way they are made, gapless. While I thought I did a pretty good job installing the CA type hinges that came in the kit, I decided that gapless certainly couldn’t hurt.

September 4, 2006 Installed the pilots
The 1:6 scale Garry pilots from Hobby Lobby ( were trimmed to fit the cockpit inserts and “glued” in using clear silicone. The rear cockpit, in front of Garry #1 was opened to provide an airflow exit. The rear pilot was given a mustache when the white edges of the airflow opening were touched up with black paint, before inserting him into the rear cockpit. The pilots were cut and inserted at slightly different angles to give them a somewhat different look, even though they are the same “fellows.”
The trimmed pilots weighed 11.5 grams. I have added 15 grams to the total weight of the plane to reflect the added weight of the silicone.
Last edited by Ken Myers; Sep 05, 2006 at 10:41 AM. Reason: Added pilot information
Aug 16, 2006, 07:46 AM
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(4) The Power System:

Battery: Skyshark RC ( 4 Cell 4000mAh Li-Poly $84.95 with delivery and taps, mfg. given weight 12.4 oz. (351.5g)
Measured weight including 2 Anderson Power Pole connectors, Velcro and pull string – 12.7 oz. (359.2g)

TowerPro 3520-6 (originally posted as 3520-7, because that it what it was supposed to be) brushless motor/w wire and 3 connectors (APP), measured weight: 9.0 oz. (255g)
Backmount w/screws, measured weight: 0.44 oz. (12.6g)
Prop adapter, washer & 2 nuts, measured weight: 0.89 oz. (25.2g)
APC 11x8.5E prop, measured weight: 0.75 oz. (21.3g) – Reamed to 8mm and balanced with clear packing tape on the rear side of the light prop blade.
APC 12x6E prop, measured weight: 0.81 oz. (23.0g) – Reamed to 8mm and balanced with clear packing tape on the rear side of the light prop blade.
4 mounting bolts, nuts and standoffs, measured weight: 0.6 oz. (17g)

Motor Total: 11.7 oz. (331.1g)w/APC 11x8.5E
Motor Total: 11.74 oz. (332.8g) w/APC 12x6E

Other: Make/break connector, 4 APP connectors and wire, measured weight: 0.59 oz. (16.6g)

Power System Total: 24.99 oz. (708.4) w/APC 12x6E

Motor Note: There is a thread in the Power Systems area here about this motor.
It is a very long thread and still continuing as of Aug. 25, 2006. The most important thing to note in the thread is that there seem to be two versions of this motor.
I tested the version that I have and found it to be the “hotter” wind (sometimes called the TowerPro 3520-6) with a Kv of about 720/730.
The motor and ESC were purchased as a combo from Milton, an RC Groups member, and delivered for $97US.

Collected Motor Data:
May 2006
Kv using drill press and Radio Shack Multimeters #22-188 & #20-168A (one used to verify the other) 730.4
ESC: Castle Creations Phoenix 45 default settings, readings are from a Hyperion Emeter and are averages of 5 readings 5 seconds apart with battery hot of the charger

No load 13 cells: 16.25v, 4.76 amps, 11,940 RPM
No load 14 cells: 16.94v, 4.86 amps, 12,456 RPM

14-cell data:
APC 12x10 pattern – 12.74v, 40.93 amps, 521.7 watts, 8060 RPM
APC 11x7E – 13.78v, 30.75 amps, 423.7 watts, 9132 RPM
Rev-Up wood 10x7 – 14.23v, 24.93 amps, 354.8 watts, 9666 RPM
APC 9x5 sport – 15.25v, 15.86 amps, 242 watts, 10,744 RPM

True RC 5S1P 4000mAh – Phoenix 45
APC 10x6 sport – 17.13v, 34.5 amps, 591 watts, 11,400 RPM

Skyshark RC 4S1P 4000mAh
APC 11x8.5E – 13.39v, 35.5 amps, 475.2 watts, 8606 RPM

August 14: data after replacing the shaft and using the TowerPro 60-amp ESC as the Phoenix 45 is in a different plane. I will check the 11x8.5E when it arrives with the plane. The 11x8.5 is what I will be using on this plane.
APC 11x7E – 13.85v, 29.3 amps, 405.2 watts, 8838 RPM

August 24 - Initial Prop: APC 11x8.5E (Used on the first four flights)
*Amps: 32.3
*Volts: 13.66
*Watts in: 441
*Wide Open Throttle RPM: 8500 (rounded down ever so slightly)
Prop Pitch Speed: 68 mph (This draggy plane will never reach that speed. Most likely in the 50 mph range.)
*Data gathered using Hyperion Emeter, components used in test; Skyshark 4S1P 4000mAh Li-Po battery, TowerPro 60-amp ESC, TowerPro 3520-7 (really –6), APC 11x8.5E thin electric prop.
Elevation: Croswell, MI 736 ft./224.3m,
Weather: Ambient Temperature: 74F/23C, Barometric Pressure: 29.92 in./1013.2mb rising, Dew Point: 68F/20C, Humidity: 82%
5 data points were captured approximately 5 seconds apart near the beginning of the pack use and the numbers represent the average of the five data points.

August 28 - Second Prop: APC 12x6E
*Amps: 32.6
*Volts: 13.70
*Watts in: 447
*Wide Open Throttle RPM: 8550 (rounded up ever so slightly)
Prop Pitch Speed: 49 mph (Probably going to be better for this draggy.)
*Data gathered using Hyperion Emeter, components used in test; Skyshark 4S1P 4000mAh Li-Po battery, TowerPro 60-amp ESC, TowerPro 3520-7 (really –6), APC 12x6E thin electric prop.
Elevation: Croswell, MI 736 ft./224.3m,
Weather: Ambient Temperature: 73F/23C, Barometric Pressure: 29.92 in./1013.2mb rising, Dew Point: 63F/17C, Humidity: 71%
5 data points were captured approximately 5 seconds apart near the beginning of the pack use and the numbers represent the average of the five data points.
Last edited by Ken Myers; Oct 29, 2007 at 07:47 AM. Reason: Added data for APC 12x6E prop
Aug 16, 2006, 07:47 AM
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(5) Onboard Radio Components:

Electronic Speed Control: TowerPro 60A w/5 APP connectors, measured weight: 1.41 oz. (40g)
There is absolutely nothing to recommend this ESC except that it is really cheap. I am only using it because I have it. Do NOT get one! TowerPro has replaced it with a 65-amp version, but there are still a lot of the 60-amp versions in the supply chain under various names. It requires excellent cooling or will shut off in flight!
Receiver: FMA Extreme 5 w/antenna & small strain relief made from servo arm end, measured weight: 0.46 oz. (13.1g) (the Extreme 5 is out of production so I now recommend the FMA M5v2)
Receiver Battery: SR Batteries ( 500H Series, 4 Cell Pack, mfg weight: 2.1 oz. (59.5g), measured weight with lead/connector & Velcro: 2.3 oz. (65.3g)
Switch: Horizon Hobby Expert Standard Switch w/Charge Cord, measured weight: 0.38 oz. (10.8g)
I found it surprising that it weighed almost as much as the receiver!
measured weight: 0.40 oz. (11.3g)
I found it surprising that it weighed almost as much as the receiver!
*Cirrus 12” “Y” harness: measured weight 7.2g
Generic 5" servo extension with red wire clipped for ESC: measured weight 2.8g
Hitec HS-225: measured weight
with arm/screw, grommets & brass collets and 4 mounting screws: 1.21 oz. (34.2g)
Hitec HS-81: measured weight with arm/screw, grommets & brass collets and 2 mounting screws: 0.64 oz. (18.2g)
*Hitec HS-85BB: measured weight with arm/screw, grommets & brass collets and 2 mounting screws & Horizon Hobby Expert Electronics 12” servo extension Standard: 0.91 oz. (25.8g)
*Hitec HS-85MG BB: measured weight with arm/screw, grommets & brass collets and 2 mounting screws & Horizon Hobby Expert Electronics 12” servo extension Standard: 1.00 oz. (28.6g)

Total measured weight: 8.68 oz. (246g)

Transmitter is a Hitec Eclipse 7
Last edited by Ken Myers; Aug 19, 2006 at 06:50 PM. Reason: added 5" servo extension
Aug 16, 2006, 07:47 AM
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Ken Myers's Avatar

(6) Flight Report:

August 26, 2006, Maiden and Three Other Flights:

The maiden flight took place at the Midwest RC Society 5 Mile Rd. flying field located near Plymouth, MI, in the late morning of August 26, 2006. The sky was totally overcast, as it had been raining not too long before I arrived at the field at about 10:00 a.m. The temperature was in the high 70-degrees F. Wind approximately 10 mph mostly from the south and southeast with the strip orientated basically east to west. Therefore it was pretty much of a crosswind. The humidity was quite high.
I stood behind the plane for takeoff to get a good view of the tracking. As it started its takeoff roll, I corrected with right rudder. I let it build up speed on the ground and used the elevator carefully to lift it gently into the air. It took a lot of trimming to get it to fly “hands off.” I had to put in what I thought was an excessive amount of right aileron and right rudder. Up trim was also added to the elevator. Once the plane was trimmed out, I gained more altitude, slowed it down and checked the stall characteristics. There didn’t seem to be any. The nose just dropped. I made several pass lining up on the field to practice landing. The one thing I did notice was that none of the “turning” controls aileron/rudder are very effective at slow speed.
I did one loop. It was okay, but I was not impressed with its size. The size of loop is one of my criteria for judging how well an airplane flies. Since I had flown my Fusion sport plane first, which is capable of performing any size loop I want, the Ryan’s loop seemed “small” by comparison.
I did one roll and it made my stomach jump. It rolled extremely slowly to the inverted and then “flopped” extremely quickly around from the inverted state back to upright flight.
At the five-minute mark of the flight, my timer started to beep, and I lined up for a landing. I didn’t want to over fly the pack, as it was the same pack that I had used to collect the motor data earlier in the week. It was not one of my best landings, but everything had survived, including the pilot on the ground.
The post flight physical inspection showed that the elevator was approximately level with the horizontal stab, so it may have been set a little low and I hadn’t noticed it. There was a large amount of right rudder and right aileron showing in those surfaces from the trimming.
Three more flights were flown on the very rough field. Several more loops were completed, inverted flight, more “scary” rolls and stall turns. I felt that the stall turns were not as “tall” as I expected before running out of power. The plane did not have the speed that I had anticipated in straight-line flight. With its wing braces and rigging wires, it must be draggier than I thought. Inverted flight did not require a great mount of elevator pressure.
The folks at the field, and there were quite a few, both electric and glow fliers, thought that it flew “very well” to quote them. They also commented on how “nice looking” it was on the ground and in the air.
As the pilot/assembler I had a little different perspective. It is certainly not as good as I want it to be.
I have several “fixes” in mind for some of the flight problems that I noted and I am planning on removing all of the covering from the bottom of the wing and redoing the whole panels to make the bottom “look better.” I WILL NOT be using the Sig AeroKote iron on covering, even though I have a lot of it left! It is awful, and my friend, Bill Brown, who had also tried to use it on one of his planes, confirmed this.
Unfortunately, I did NOT perform the MOST IMPORTANT flight test. That is the dive test to check the center of gravity! Dang. After talking with Keith about some of the flight characteristics, we concluded that it may be a bit nose heavy. The C.G. is set up at 2.75 in. from the leading edge at the moment.
I will be checking the lateral balance of the wing. I will also be checking the wing for possible warps.
I am going to try an APC 12x6E, as I believe the plane is over pitched at the moment. With the high drag there is no chance of it reaching the pitch speed of the APC 11x8.5E. I will report the new motor data as soon as I collect it.
All and all this seems to be a pleasant plane to fly, and it does look good in the air. So far, it seems worth the effort, if not the price of the kit.

EFO member, Paul Sockow took the stills with my camera. For some reason I had it set on wide-angle instead of telephoto, so some of the images were “blown-up” using my Photoshop Elements and aren’t that great, but thanks Paul!

EFO member, Dave Stacer shot and edited some video. You can find it here:

September 2, 2006 – Flights 5 – 9
When I arrived at the field about 9:30, the temperature was in the mid-60 degree range. The winds were out of the east at 10 mph to 15 mph. Not the best day for trimming a plane, but since I had set the CWL for this kind of flying, it worked out just fine! Keith arrived about 10 and set up his planes, and then he took up the Ryan.
Keith took it up for the first few minutes of the initial “retrim” flight. It only took a bit of tweaking and it was flying as well as it can fly, especially considering the pilot. J Geese, am I lucky to have him for my “test” pilot. I took over about 2/3 of the way through the flight and made the landing, and yes, it was flying better compared to a week ago. Upon landing, Keith noticed I still had the left elevator half up slightly and that just a touch of right aileron correction had been trimmed in (WAY better than last week!), so I took the clevis in one turn and all was sort of well. While looking closely at the horizontal stab we noticed a small twist on the left side of the stab near the tip, also the left elevator half has a “bow” on the edge near the rudder.
All flights were fine now and the rolls are GREATLY improved with the differential I had added to the ailerons and using the throws that I have noted. The CG is in the proper place and no equipment was moved. Takeoffs and landings are this plane’s strong suit. They are absolute child’s play. It flies okay and looks good in the air. I am satisfied that I have it flying as good as it can now.
The pilot busts arrived today, Saturday September 2, up in Croswell, so I’ll get them in the first of the week, when I get back up there.

Moving from the APC 11x8.5E, as flown on the maiden flights, to the APC 12x6E was an excellent choice.

September 16, 2006 – Flights 10 – 11
It was a mild, late summer, Saturday morning. For a change, the winds were light, but still out of the south, which is crosswind at the Midwest RC Society 5 Mile Rd. flying field. I had two more flights, feeling very comfortable with the plane now. I worked hard to do “scale” takeoffs and found that the plane would easily lift out of the long grass at less than full power, and look good doing it. I noted that only a very slight touch of down elevator was needed to “pretty up” the rolls, and that it didn’t take much down to maintain inverted flight. The power seems right for “scale” flying, and I must admit that I like flybys at low altitude, down the center of the runway, so that I can enjoy the pilots.
While this was a frustrating build, it seems worth it now.
I did need to add a touch of glue to one of the exhaust stacks that had gotten “bumped” in the ride down in the pickup bed. I had Jim Young help me balance the plane on a wing tip to glue the stack to the cowl, since it was already assembled, and he noticed how much the wing flexes, even though I have added the shear webs and tightened up the covering. He was NOT impressed.
With reasonable flying qualities and great takeoff and landing characteristics, this has become a fun plane to fly. I hope to keep it in my hangar for a long time.

October 7, 2006: Flights 12 – 15
I arrived at the Midwest field about 9:30. Set up the plane and took the first flight in almost no wind at about 10:15. It was a beautiful fall day here in Michigan. It was sunny and the temperatures reached the 60’s by mid-day. By 11:00 the winds began to pick up a little to about 7 mph - 10 mph, but not bad at all. The plane flew better than ever because of the cooler weather. The cool weather didn’t appear cool enough to affect the Li-Po batteries.
I did about every maneuver that I am capable of, and the wing held together. As I have noted before, takeoffs and landing are a joy with this plane.
I choose to fly two five-minute flights with the Skyshark 4S 4000mAh packs because a 10-minute flight is just too long for me. Also, I only have to change the battery pack after every other flight by doing so.
In the long run, I am happy to have added this plane to my fleet. It still draws a lot of positive comments from those who’d not seen it before. Unfortunately, I have to tell them, you really don’t want one.

November 4, 2006: Flights 16 – 19
The temperature was 44 degrees F for most of the day at the Midwest 5 Mile Road flying field with the wind about 5 mph to 7 mph out of the south, which is crosswind for this field layout. There were eight EFO members there having fun flying on this sunny morning and early afternoon.
The first three flights were very good, having kept the Li-Po batteries warm until use. On the fourth flight, the elevator trim seemed to have changed from the preceding flights. A couple of clicks of elevator trim and it was flying okay again, for a brief period, and then the trim needed adjusting again.
I decided to land about 4 minutes into the flight. I looked at the plane, but didn’t notice anything. Since it was my last flight, I loaded the plane into the truck.
When I got home and took the wing off, the wing hold down assembly fell off and down into the fuselage of the plane. DANG! Had I gotten lucky or what? The only thing holding the wing on were the struts and the design of the wing hold down assembly, which sort of holds it in place. Whew! One of the triangles of the assembly was totally missing. The assembly appeared to have been glued in using some type of hot melt glue. The remaining glue was extremely easy to pull off with my fingers only. I made a new triangular piece and epoxied the assembly back into the plane.
I’ve added photos showing the missing wing hold down assembly, the broken assembly and repaired and replaced wing hold down assembly.
Last edited by Ken Myers; Nov 06, 2006 at 09:14 AM. Reason: WARNING! Poor glue choice for wing hold down
Aug 16, 2006, 07:48 AM
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Ken Myers's Avatar

(7) Conclusion

Measured Data:
Plane: Sportsman Aviation Ryan STA Almost Ready-To-Fly
Supplier: Hobby People
Importer: Global Hobby
Type: Sport Scale
Building Skill Level: advanced to expert
Flying Skill Level: advanced to expert
Approximate scale: 1:6.23 (based on wing area)
Wing area: 460 (see note in Assembly and Modifications section)
Wingspan: 56.625 in. (1438mm)
Length: 37.75 in. (95.9cm)
Ready to Fly Weight: 71 oz., 4.44 lb., (2015g or 2Kg)
Wing Loading: 22.2 oz./sq.ft.
Cubic Wing Loading: 12.44 oz./cu.ft. (On the heavy end of my acceptable.)
Second Prop: APC 12x6E
*Amps: 32.6
*Volts: 13.70
*Watts in: 447
Watts in per pound: 100.7
*Wide Open Throttle RPM: 8550 (rounded up ever so slightly)
Prop Pitch Speed: 49 mph (Probably going to be better for this draggy.)
Completed Airframe weight: 37.41 oz. (1060.6g) – 52.6% of RTF weight
Power system weight: 24.99 oz. (708.4) – 35.2% of RTF weight
Onboard radio system weight: 8.68 oz. (246g) – 12.2% of RTF weight
Flying area required: RC Club Field
*Data gathered using Hyperion Emeter, components used in test; Skyshark 4S1P 4000mAh Li-Po battery, TowerPro 60-amp ESC, TowerPro 3520-7 (really –6), APC 12x6E thin electric prop.
Elevation: Croswell, MI 736 ft./224.3m,
Weather: Ambient Temperature: 73F/23C, Barometric Pressure: 29.92 in./1013.2mb rising, Dew Point: 63F/17C, Humidity: 71%
5 data points were captured approximately 5 seconds apart near the beginning of the pack use and the numbers represent the average of the five data points.

The Good Stuff:
1.) 3-inch wheels for good grass field operation.
2.) A decent cowl.
3.) The finished model has a pleasing, somewhat scale-like appearance when completed.
4.) The graphics are already applied.
5.) The covering job was, overall, quite good.
6.) The airframe weight is somewhat reasonable for this size glow plane, but still heavy by electric standards. The CAW for my 568 Fusion sport plane ( is 32 oz. It is a much larger plane but EXTREMELY well designed by Steve Pauley in Minnesota, USA.

The Bad Stuff:
1.) It has possibly the worst possible wing structure design. In Keith Shaw’s “Building and Flying Electric Sport Scale” ( he states:
“… Many designers put just a spar on the bottom. That doesn't make sense; it should be on the top. One of the worst designs is: (see graphic in the attachments area)
It's probably the weakest wing design. Putting the spar on top helps a little, but not much. Using a top and bottom spar with shear webs and making an "I" beam jumps the strength by a factor of 10 at least. The shear webs are really important.
Even light 1/16" balsa will work wonders. Make sure that the grain is vertical. It's harder to cut, but they are stronger.”

With the possibility of catastrophic wing failure, this plane is really unacceptable.

2.) The wing bolt hold down assembly is glued to the fuselage with an unacceptable glue and will easily break free of the fuselage former and could cause the loss of the wing while in flight.

3.) The supplier and importer provide incorrect information about this plane. The wing area is almost 10% less than stated in the manual. That means that their published wing loadings are incorrect as well and should have been 18.9 oz./sq.ft. to 21.3 oz./sq.ft. based on their given RTF weights This is not a huge deal, but shouldn’t happen. The 288 given on both the Hobby People and Global sites is totally inaccurate.

4.) There are several discrepancies between the parts provided in the kit and the parts pictured and noted in the manual.

5.) There are extra parts in the kit like the black axle “spacers”, which were not noted in the manual and they wouldn’t have worked as I guessed at what their purpose might be.

6.) The landing gear blocks are not wide enough for the provided landing gear straps.

7.) The original wheel fairing/spat attachment is flimsy and the spat covers too much of the wheel for good grass field operation.

8.) The wing brace attachment is a problem as it inhibits easy wing removal.

9.) The way the rigging wires are to be done, according to the construction manual, leaves a lot to be desired.

10.) The elevator pushrod exits were not located in the correct place on the fuselage in my kit.

11.) The provided windscreen is the wrong style for this plane. It should be “rounded”, not “squared.”

12.) The molded plastic parts, cockpit inserts, fuselage fairing and wing brace fairings are not molded in their appropriate colors. They are painted. When trimmed, they require painting of the “raw” edges so that the white of the molded part is not visible. The white really stands out against the black of the cockpit inserts.

13.) It has a balsa dowel wing leading edge. A birch dowel would be better or a carbon fiber tube.

14.) The wing needed a lot of tightening with a heat gun to add some rigidity to it.

15.) There was an excessive amount of time to do tasks that should have been easy and quick like screwing on the landing gear, installing the elevator pushrod and the rudder pull-pull system. It was not the “quick” assembly that I had hoped for.

16.) The butted plywood for the center ribs, used to mount the leading edge of the wing to the fuselage, is prone to breakage. I leaned this on my Stik from the same company.

17.) There is only one wing hold down bolt when two would be much better.

18.) The slot for the horizontal stabilizer as approximately 3/16” too long.

I was very disappointed in the amount of time it took to assemble this ARF. I was extremely disappointed to find out that I purchased a plane with a built-in possibility of catastrophic wing failure, especially since I will be carrying Li-Po batteries onboard.
Last edited by Ken Myers; Nov 06, 2006 at 09:18 AM. Reason: Added 18th PROBLEM!
Aug 16, 2006, 08:15 AM
jrb's Avatar
Hi Ken!

Posting so I can closely watch your build; almost walked out of one of our local hobby shops with one for $90 (IIRC).

Looked at it to make a stand off scale 3KR (PT-22 Recruit) w/swept wing and a radial engine – add some dummy jugs.

Planned to do a 3S set-up (geared via MEC new MiniBox) and swap the pack in/out via the front cock pit – have two TP4200-3S2Ps

Along with adding sweep to the wing I was going to do the mains differently – not tie down the aft rail, but rather leaving it “float” so the front work as a torsion bar absorbing landing loads. Also, would have beefed up the wing a bit, I heard “The wing on this model is weak and the gear is a little difficult to deal with. It will fly on a 25 two stroke, so I'm sure your estimate on power is right on. It's a pretty nice flyer. Looks good in the air.”.

BOL luck with the maiden, waiting for your updates.

Aug 16, 2006, 09:25 AM
Registered User
Ken Myers's Avatar
Hi Jim,

At least someone is watching. Just came in from the shop. Replaced the bad connector with a new good one. Don't want to lose radio power on this one!

Originally Posted by jrb
Looked at it to make a stand off scale 3KR (PT-22 Recruit) w/swept wing and a radial engine – add some dummy jugs.
Yep, I'd thought about that as well, but want to get it into the air as quickly as possible.

Originally Posted by jrb
Planned to do a 3S set-up (geared via MEC new MiniBox) and swap the pack in/out via the front cock pit – have two TP4200-3S2Ps
How many amps were you planning on drawing with just a 3S setup? Just curious.

I will be sure to check the wing construction and attachment. I'm not thrilled with a single bolt in the rear and single plywood front attachment on the wing. I might have to do something about that. The single plywood front wing attachment broke on the first oops of the Low-Stik from the same company.
Last edited by Ken Myers; Sep 03, 2006 at 01:04 PM. Reason: statement error
Aug 16, 2006, 10:13 AM
jrb's Avatar
30ish Ken.

I’ve flown my Good Ole American Flyer (Hobby People ARF too) on 3S (re-pinioned the MEC SuperBox) and it certainly flew as I would want for a PT-22; though I do prefer its hopped up performance with 12round (Two Six Packs!) even @ 6# RTF. This article makes reference to a couple of set-ups I’ve used in the GoAmF: .

FYI here’s a shot of some packs I made for an up coming thread about A123s. Four of them do well in place of 12R & a bit better than 3S LiPo: Weights respectively: 12.5, 11.5 (lighter too, less than ¼” all around), & 19.5oz. for 12x1950FAUP (Zapped).


Aug 16, 2006, 10:26 AM
<- Balsa flies better ->
wolw's Avatar
Sure looks promising Ken

Anyone know if there's anyone in Europe selling them (the Ryan STA that is) ?
Can't seem to find one.


Aug 16, 2006, 09:22 PM
Registered User
I seem to remember a review on this plane (RC Report?) where the reviewer was concerned that the wing itself was flimsy and he didn't recommend pulling high-g manuevers with the plane. Maybe it needs working flying wires and struts to help stiffen it up? In spite of that, I think this is a nice looking plane and I look forward to your report on how it flies.

Aug 17, 2006, 01:41 PM
Registered User
Ken Myers's Avatar
Not sure about how to strengthen an already built wing, but personally, I would NEVER recommend a .46 2-stroke on this plane!
Aug 18, 2006, 08:52 PM
Hooper, full throttle!
Tommy D's Avatar

Very well written and your attention to detail is excellent!


My Pops had one of those PT-22's when he was in China. Somewhere in all his photos from "the day" are some great BW shots.

Your photos were excellent!

Tommy D
Aug 19, 2006, 06:43 PM
Registered User
Ken Myers's Avatar


Thanks Tommy.

I do appreciate your comments. There are some problems with this kit, but I hope the hassle is worth the effort. Didn't get as much done today as I wanted to, but had a good time at my son's this afternoon.

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