Flyguy Promotions received a contract from Wide Angle Group in early June to produce a 10 foot flying Loon based on the Minnesota United Loon logo. The Loon was flown as part of the Major League Soccer (MLS) pregame covered by ESPN. Mike Frandsen, Bob Simon, Dave Encinas and Otto Dieffenbach built the Loon in 5 weeks with first flight on July 10. Emily DeJoode, Manager of Ampdraw Hobbies in Encinitas joined Otto as his far corner spotter for the performance. Three rehearsals and the performance flights were flown on August 8, 9 and 10. FAA and FBI approvals were obtained prior to flight operations.
The performance and project were considered great successes by ESPN, MLS and Minnesota United.
Now that I have completed the top section it is time to move to building up the lower section of the fuselage. In this process we will also be making a change to the build. That is moving the servos back to the original position (behind F5 to F7) which was just over the wing, where I had made the hatch for the access to the battery. You can see that in the drawing.
Ok, let’s get started in building the bottom section. The first thing I did was to install the formers into place, making sure all were 90 degrees from the top stringers which were pinned down to the board when building the top section. The wing saddles were also installed at this time too.
At the same time, I installed the push rods guide tube into place. I installed the servos and worked on the push rods to the correct length. Once that was completed, I placed the tail wheel support plate in place for a dry fit and made sure that I did have the correct length. As always it was perfect.
To make sure that it was correct, I connected the servos to my receiver and made sure the control arms were center. I then completed the rudder and glued in the rudder block to the control rod and again made sure that all was center so I would not have to do it at a later time. The elevator was done the same way, but I have not glued it yet into position. If adjustments need to be made, I can do that on the radio.
The one and only DC-1 served a full career with TWA, then was sold to Howard Hughes. Hughes sold the airplane to the Spanish government, but the DC-1 met its demise after an engine failure during takeoff in the 1940. (Guess they didn’t read the “Engine Out” section in the manual)
Framing the fuselage Top: Fun part about building Top Flite kits is that you build right off the drawings. Got wax paper, laid it down and I grabbed all the formers including grooved main stringers. These two stringers I soaked them in water to create the fit of the curve for the nose of the aircraft. Pinned it to the board and let it sit. I also installed the cabin crutch to help form the main stringers. Once that was done, I then completed pinning down the stringers to fit the drawing. Next was to place the formers into place just to fit, but not yet glued in place. Here is where I had to create a hatch for the battery, instead of taking the wings off like I have to do with my Cessna. I replaced two formers. The formers that come with the kit are 1/8” So I will be replacing them with a ¼ “thick. These two formers will be used for the opening of the hatch. The formers that came with the kit are going to be used for the hatch as you will see in this process.
Without a modern passenger plane. TWA was not about to let United Air Lines corner the entire market with Boeing’s 247. TWA initiated a program of their own to develop a modern airliner. Douglas responded with the most advanced and the most controversial design, namely DC-1. TWA ordered one unit and in 1933 the first DC-1 rolled off the assembly line in Santa Monica, California. The DC-1 was bigger and sleeker than any other liner in the industry, including Boeings Model 247!
As you can see in the above photo how the formers were fitted into position. Starting with the nose of the aircraft is where I started to glue the formers in position. For the hatch section as I mentioned I am changing the formers with ¼ “thick. I then cut the two original formers and glued the lower section to the replacement ¼ “formers. The top half will make up the hatch. In between the two ¼” formers I cut the middle former to match the hatch and the bottom part, I cut out the middle and only used the sides, also show in the photo.
By Jovi Murek
Hello Club members, Here I am getting ready to start to build the DC-3. Starting off with the tail section of the aircraft. The first part was to make the skins. Here I took two sheets of 1/16 x 3 x 30 and glued the two sheets to together so the outcome would be 1/16 x 6 x 30. I created three sheets, two for the stab and one for the fin and rudder. Now starts the fun part, building! Now that we have gotten the skins ready, I’m starting to build the Stabilizer. As show in the picture I have all the parts laid out on the building board and preassembled them before gluing them into position.
After presiding over various projects including the Matin MB-2 bomber at the Glenn L. Martin aircraft company, Donald W. Douglas Jr, born April 6, 1892, co-founder the Davis-Douglas Aircraft Company in the spring of 1920 with help from David Davis, a millionaire with a great desire to fly. By the mid 20’s Douglas designs were well known throughout both the civilian and military aircraft industry.
[This article was borrowed from the April issue of the Ampeer. Thanks to their Editor: Ken Myers]
By Andrej Marinsek
Many years ago (Model Airplane News, Dec. 1997) an article was published in this magazine titled “3D Wing Loadings” (Three dimensional wing loadings) by Larry Renger; it was recently published again on the internet in a slightly cleaned up version. Its different approach to a specific modeling subject is interesting but, as it will be shown later, has some problems. The concept of the 3DWL, though correct in one respect, has otherwise rather limited reach and leads to some vague interpretations and questionable conclusions. The 3DWL persists around in different forms and publications and seems to be, nowadays, the most advertised and supposedly even the only appropriate approach for estimation and comparison of some model performances. This is somehow surprising, so it needs to be addressed in some way.
2. General remarks
Coherent units from the International System of Units (SI) are used in calculations as they are clearer. In most cases only one unit is attributed to a certain physical property and numerical transformations are simpler or not needed at all.
Instead of the term weight (W), which is strictly speaking, a kind of force, the expression mass is used (designated by the letter m), which is the proper name for the physical property measured in kg (lb., oz., etc), and is employed in all calculations here.
3. Agility of models
The motion of models in the air can be on one side described by the words like “agile” or “hot” or “docile” or “flyable” or whatever expression is used to appreciate the performance of models in flight. However this can be pretty undetermined and subjective.
On the other hand, some objective (given by numbers) performance parameters exist. With regard to the lateral axis of models, some performances directly depend on the lift force. These are the minimal speed in horizontal flight vm (stall speed), the minimal absolute turning (or circling) radius Rm and the minimal relative turning radius (RTm), which will be defined and discussed a bit later.
Also, some settings (such as the center of gravity) and a number of model properties, for instance wing profile, low/high wing, aspect ratio, tail (distance from the wing, area, position), the size of rudders, propulsion, thrust vectoring, etc. considerably affect certain performance parameters.
By Mark Davis
I recently had a problem with a servo randomly twitching, and was able to solve it, so wanted to share what I learned. It is a large plane and there are 10 feet of wire between the Rx (Spectrum 12310T) and the servo (Hitec 7950TH “ultra torque”). Because of this, I ran 17 gauge power/ground, and used MR30 connectors (instead of 20gauge heavy duty extensions with normal servo connectors). But even with this, the servo exhibited erroneous twitches, especially when moving.
I found the problem could be remedied by placing (near the servo) a capacitor across power & ground, or a signal booster, or both. This problem depends on the servo also, and for example the D625MW did not exhibit the same issue, and needed no remedy. It appears that this is because Hitec 7950TH (“ultra torque”) draws high current for brief snippets of time, and thus causes large power transients. These will appear also on the ground, and therefore the PWM signal can be affected. A power bypass cap by itself fixed the problem. A signal booster by itself was helpful but not entirely reliable (Spektrum and Hitec both make them). I believe the best solution is to use both a supply capacitor and a signal booster, based on the oscilloscope plots below.
First, some background information and definition.
When ground currents are present, we have to designate a specific point as “0 volts”. In text below I treat the ground at the receiver as the definition of 0v. The oscilloscope probe was connected with its ground near the servo, 10ft away. So it is not necessarily at 0v, by this definition.
The oscilloscope horizontal scale (time / division) appears in the upper left of the screen next to the letter “H”. The vertical scale for each channel (volts/division) is shown in the lower left of the screen.
When a servo was connected, it was connected without load or with light load (sitting upright on a table, or in some cases on its side, so the arm was just lifting the weight of the servo).
The capacitors I had on hand were 8200uF 10v, and 4700uF 16v. Since my system runs on 2S LiPo, this is sufficient voltage.
The signal boosters I tried were:
- Spektrum Signal Line Voltage Booster SCMCP
- Hitec Signal booster HRC58496
I have grouped scope traces into 5 sections:
|Section||Servo||Capacitor Across power/ground||Signal Booster included|
- NO CAP, NO BOOSTER : SERVO SHOWS ERRONEOUS MOVEMENTS.
First see picture 1B below. I put a scope on the signal wire. You can see the servo is approximately centered here, with a 1.5ms positive PWM pulse. But you can also see frequent artifacts. I didn’t immediately notice a very regular period, but they seemed to occur every 4-10ms. Unfortunately I didn’t capture the power line here, but from later plots I believe it would show exactly the same artifact at double the magnitude (I’ll explain why later).
Now consider the structure of one such glitch. It appears the servo decides to draw a large amount of current for about 50us – 200us, depending on which glitch we are looking at. This pulls down the power line voltage, and pulls up the probe ground (servo ground). The signal is looking into a high-impedance FET, and so draws insignificant current, and so should have insignificant voltage drop even over 10ft of wire. This explains why we see the oscilloscope voltage go negative at the start of the glitch; the signal wire remains at 0v but the probe ground “bounces” up due to the current being dumped into it. The voltage appears to be asymptotically approaching a steady state value (with the expected exponential shape) by the end of the 200us. This steady state should be the current of the servo times the wire path resistance. Then when the current draw stops, the inductance of the wire keeps pushing current for a small transient. Thus, the opposite effect will occur; The voltage of the local ground will dip below 0v and so the signal wire sitting at 0v appears to go positive on the oscilloscope. Note that this positive glitch can be quite high. This plot has 1v/division, so the first glitch captured here is around 1.6v, which I’m guessing is quite close to the detection threshold for a PWM pulse.
Picture 1B: No capacitor, no booster
My latest purchase is this Xfly T7A from Bitco Hobbies or Banana. I got a pre-purchase deal for $150 on a recommendation from Chris Wolf’s youtube channel. I love this thing ….65mm edf, fixed gear and 4s 2200 lipo. Nicest flying jet I own. Fast very nice finish and sounds great. I highly recommend it. Bill A.
By Steve Manganelli
The term OOS or “Out Of Sight” is a Free Flight Model Aviation term referring to a model catching a thermal that carries it up and out of sight, generally never to be seen again. I can’t imagine the melancholy feeling of watching the product of your hard work disappear before your eyes. On one hand, you have validation of your model building skills; on the other, sadness at the loss of your creation. I’ve heard stories of models turning up in a cornfield some miles downwind of the field years later or what not, but that is nothing like my OOS experience!
For my story, turn the clock back to about 1971/2, before I could afford the luxury of Radio Control. As a geeky 11/12 year old, with friends of similar ilk, if it flew, floated or ran, we had to play with it…or destroy it. My friend Jeff and I had a motto : “cure it or kill it”. All of our experimental unguided air vehicles either had to fly successfully or be demolished in some spectacular fashion.
One day, a foam wind-up rubber band powered airplane with a span of maybe a foot and a half had reached that point of no return. It was doggy as a rubber powered model and by then I was experienced with balsa, dope and tissue and knew how to do better. This foamy was called “Major Roscoe Hawks Amazing Flying Machine” (MRHAFM). Actually I remembered the name a little differently but with the miracle of Google I actually found one under vintage toys, circa 1971 and no, I didn’t buy it so I could relive the soon to be described stupidity!
MRHAFM has roughly the proportions of a high wing Cessna. Clearly if a rubber motor was enough to fly it, a Cox .049 should be oh so much better! At least we had enough sense to chop off most of the nose and epoxy on a scrap of 1/8 plywood for a firewall; surely it would need some up thrust so we did that too! Next, we bolted on a cantankerous Cox “Golden Bee” 049, the kind with the larger gas tank for a 6 or 7 minute run. In control line models, this particular engine never did more than couple laps before it quit, but for MRHAFM, we figured 10 or 15 seconds would be more than long enough to pile drive this wannabe ice chest into the ground in some spectacular fashion! In retrospect, the fuel pickup of the engine was probably on the bottom instead of the outside as needed for control line, but no matter. A final check out of the flying machine suggested it might still be a little nose heavy (ya think?) so a couple of cox glow plug wrenches were taped to the tail. Perfect, off to the nearest vacant lot we went. No need to ride our bikes to one of our control line fields (aka the nearest school field), no landing was expected on this flight!
The tank was fully fueled, the engine started and the needle valve was peaked to screaming pitch. MRHAFM was released gingerly into the wind. A steep climb ensued as the unreinforced foam wing bowed to foretell anticipated disaster, but instead she arched over on her back, we figured heading for a glorious “figure 9”. Our anticipation of a full power, straight in crash was quickly dashed. Instead, the 100 foot loop was completed missing the bushes by mere inches and another giant loop was begun, still tracking straight into the wind! This time, the bottom of the loop was maybe 20 feet off the ground and another loop started. By the third loop, Jeff and I looked at each other in unstated disbelief : “why is this thing still running?” . But run she did. Successive loops gaining more and more altitude and for some reason, continuing to track straight into the wind. She climbed higher and higher until after about 3 minutes or so, we lost both sight and sound of her; MRHAFM was gone, out of sight!
Our ecstasy quickly turned into consternation as the thought of what will happen when she ran out of gas began to go through our heads. Unlike a lightweight well-trimmed free flight model which will lazily glide down to a soft landing when it’s OOS thermal lost it’s hold on it, we knew MRHAFM would come down like a rock when our now best-engine-ever ran out of fuel. A car windshield or hood? Someone’s roof? Our chosen event venue was a vacant lot in the middle of a populated area. When last seen it was more or less over a cemetery, but we decided not to chase after it to find out where it came down, instead left the scene smartly with mischievous grins on our faces and in at least my case, a grand model airplane story to remember and recount nearly 50 years later.
My new T-28 1.1m Aircraft. I’m very excited. I’m not very good with the 800mm Aircraft, also I enjoy my job as turn marshal for the races.
Happy Days are Here Again!
Hello fellow SEFSD members. I am happy to say, now that the state of California is opening 100%, we are now open to continue our activities starting with our club meeting and a Fun Fly on Saturday June 26th. Spill the Beans will be the Fun Fly! As far as serving hot dogs, that will happen on our July meeting – so just one more month to go for goodies.
This also means that everyone who is fully vaccinated should no longer need to wear a mask. However, those remaining unvaccinated should continue wearing a mask until you are fully vaccinated. SEFSD is not going to enforce this rule. Instead, you are on your honor to use best judgment while following state and local guidelines.
Since this is our first meeting of 2021, you will finally get to meet the new board members which include your new president, me, Jovi. This is very exciting for me to meet all of you. During the past six months I have met a few of you at the field on Saturdays (which is the only available time for me to fly, something that I am going to work on and try to get out more often).
So I thought I would give a brief description of who Jovi is. So let’s get started:
I started with RC airplanes back in the mid 70’s. At that time, you had to build your airplane (Old School) and it took some time before you could actually fly. My first club was the Torrey Pines Gulls. I would head out to the glider port and spend a Saturday afternoon when the winds were blowing. There were full-scale gliders (no hang gliders were around at that time) as well and it was fun. The first glider I learned to fly was the Wind Ward with a KRAFT radio. The Hobie Hawk was my best glider to fly. It was fast, it could climb in the thermals, it soared over the cliffs and if you did it right, catch your plane with one bounce to slow it down. From the mid 80’s to mid-2000, I spent hours away from flying.
I was lucky to travel the world with the company’s I had worked for. I spent 3 months in Korea working with Samsung’s D Ram chips. The town I stayed in was called Onyang which had no American food to speak about. I just lived off French fries and OB beer at this one watering hole. Half way thru my tour I found a restaurant that had steak and A1 sauce on the table. The steak was good!
I have been all over Europe, Brazil and even down in Malaysia! I arrived in Kuala Lumpur at 3:00 am after a 22 hour long flight, needless to say I was ready to get out of the aircraft, but I was not expecting on the humidity at 3:00am and the heat…OMG. During those times my mind was still on model planes and during the off times I would be building a TopFlite kit and would spend years building it. But as the years went on I would fly here and there. I would have a nitro airplane out in the sand dunes to go fly around. It was a challenge with sand, thick sand, but having balloon tires, a 90 size 2-stroke engine and a tune-pipe turned out to be no problem! Out by Lake Mead they have a runway setup for models, but not many fliers would show up. Plus it was 100 degrees when I was flying, so it was nice to be the only one and having the background of the Lake Mead was sure nice. Took my toy trailer out Lake Mead RV Village; yeah, those were the days! The field is still there. Today I work for General Atomics where we build the new launch and arresting gear for the new Ford Class Carriers using electromagnetic systems. To be exact, they are called Electromagnetic Aircraft Launch System (EMALS) and Advanced Arresting Gear (AAG). I invite you go online and check them both out, they are very cool. Today, I’m back full speed with my RC planes and I am all electric – no more nitro. I am a scale type person who just loves to fly straight and level, but I’m still working on loops and rolls!!!
I would like to take a minute and talk about safety when flying and this happened a few months ago, but it still worth mentioning:
Heads-Up”, which has three meanings: Adjective – showing that you are very aware of what is happening around you and it also goes for heads-up football. Noun – a message that tells or warns someone about something that is going to happen as an example, gave him a heads-up that an investigation was pending. Interjection – used to tell someone to look up because of possible danger or to clear a passageway. Out of the three definition of heads-up we are more commonly known as to Interjection. There are times out at the field, you hear heads-up and sometimes we just don’t look because someone say heads-up, especially when the voice projecting heads-up is not all that loud and, in most cases, we keep our conversation going with a fellow pilot until we hear from other pilots on what just happen. Aircraft down….
As part of the club’s safety, we need to Shout Out heads-up when your aircraft is in danger and you are over the pits or parking lot. The end of March there was an incident, well names don’t need to be mentioned……Ok, fine it was me and I was flying my Hawaiian Air. Take-off was perfect, then 30 seconds into the flight I was in trouble.
One of my favorite old movies is “Animal House” 1978, starring John Belushi as Bluto and in the movie is this one seen where Bluto and D-Day were helping Flounder getting revenge for having Flounder cleaning out the horse stalls and doing push-ups over a horses surprise. D-day hands Flounder a gun and Flounder goes into Dean Vernon Wormer office where the horse is and as Flounder is squinting his eyes pointing the gun at the horse, which he then points it, in another direction and fires the gun. But the sound of the gun, killed the horse. The prank-related accidental death of a horse belonging to Omega member and Reserve Officers’ Training Corps cadet commander Douglas C. Neidermeyer.
Bluto and D-Day run into Dean Vernon Wormer office and the first words coming out of Bluto mouth was, “MERRY CHRISTMAS”. D-Day goes and says, “There were blanks in the gun”, Bluto again says, “MERRY CHRISTMAS”. Those same words came out of my mouth when I was in trouble and I yelled it for all to hear. As I got some control over my Hawaiian Air I again yelled out “Christmas”. With seconds I had Dennis coming over. I hear Brad in the background, “you in trouble Jovi” ……Yes was my response. Dennis got it under control, gave it back to me and still, I was as nervous as I have ever been. Brad finally took control and landed her safely for me. Happy was I. I needed oxygen after that ordeal.
Mark came walking by me and he mention to me how effective I was in yelling “MERRY CHRISTMAS” and how everyone was alerted of the situation at hand.
Here is what happened to me, I relied on the gyro. When I took off, I thought I had the gyro on, but as I was heading downwind and when I turned base, that is when I notice I was in trouble. My Airliner was climbing and I’m looking straight up in the sky and flying over the parking lot and Sea World Dr. I was able to get back over the field. I have learned that I cannot depend on the gyro all the time in which I did depend on it. It’s a nice feature to have but something that one should not always rely on. So, I am going to learn to fly without the gyro and just keep it for safety…if that makes sense.
However, the morel of this story is when you’re in trouble, it is most important to be yelling out loud heads-up or Merry Christmas! Remember you must stay north of the fence line at ALL times. You should never be flying over the Parking lot or the Pits, for the safety of our club members and guests!
On my bench I have the Top-Flite Bonanza which I started back in late 1998. This was built to take a Satio 120 four-stroke. Wingspan 81” and the length, 63.6” also included are the following:
- Robart Air Retract w/scale Robart Struts
- Scale Navigation lights that work off two 9-volt battery’s
- Scale Interior Cockpit that is all removable
As time went by, I really never complete my Bonanza. But as of late, I got my hands back into it. She is almost ready to go, however I have a few things that need to be done, one is to replace my flap servos. I had to replace the v-tail servos. When I was moving them, I notice that the servo arm was going around in oblong circle. Not good. Change them to newer Hitec servos and were back to perfection. Theses retracts are old and not holding pressure. It is holding pressure for a good 10 minutes in which I only need about 6-7 minutes…. Maybe some risk here…I’ll keep working that problem.
The biggest task I had was figuring a way to change batteries without taking the wing off like I have to do with my Cessna 182. The Canopy is bolted down with four socket head cap screws, problem with that was getting to those bolts. I removed them and now I have a quick latch to remove the Canopy. You’ll see what I mean in the pictures. It’s actually very cool how this works. I can put the wing on and I don’t need to hook up the connectors or the air lines. Once the wing is bolted, flip the Bonanza, unlatch the Canopy, remove the interior and I have access to everything in the aircraft. Hooked it all up, connect the airlines and place the interior back into place. Where the fuel tank would have been are where the batteries now sitting.
Balancing was next, I did a rough balance and she seemed to be good with the batteries mounted up front. Out at the field on T-28 Race’s, April 10, was the day she was going to maiden! Complete check out was preformed and she was now certified to fly.
Brad did the maiden flight! She took off like an F-14 Tomcat heading towards the Sunset as seen in “Top Gun”. As he was trimming her out, he was noticing the balance may be off. She acted very weird. He flew her around and she look very nice up in the sky, you think it was a full-scale Bonanza. Time was running out and Brad was preparing for landing. She came and touch down and just rolled down the runway. I was happy, but the next flight, I am going to dial in the balance and hopefully that helps out, which it should!
Ok, I have made enough noise!
Grab your planes, batteries and radio, and let’s go Flying and looking forward to seeing you all at our Monthly Meeting!
It’s Mosquito Season!
By Steve Belknap
Recently I finally put together my JR Models Mosquito kit. I bought this kit, and one other, from former club member Fred Harris maybe 15 to 20 years ago at one of our club swap meets. It had spent enough time on the shelf. Time to build.
The kit was made in the Czech Republic 25-30 years ago. The craftsmanship is excellent but the instructions (below) are a bit primitive. The fuselage, inner wings, & nacelles are all one piece of molded fiberglass. The outer wings are built-up balsa and the tail is balsa sheet. All very lightly built.
Here are the original specs:
Span: 49 in.
Weight: 45 oz.
Motors: 2 x Speed 400
Battery: 7 cell Sub-C Ni-MH or NiCd
I looked through the kit and planned my modifications, of which there would be plenty.
First was the obsolete power system. A Speed 400 brushed motor gives an actual output of about 50 Watts due to its 50% efficiency giving a total of 100 Watts of power out for two motors. The plane is supposed to weigh nearly 3 pounds. This would have given just over 30 Watts per pound. I was looking for something more like 125 to 150 Watts per pound. So I went to the Ecalc calculator and found a Cobra C-2814/12 motor that would give me just that. I decided on a 4S-3000 mAh Li-Po and APC 7×5 counter-rotating props. I also bought 7×6 props when I want to go faster.
The Ecalc calculator told me I would get 300 Watts per motor out. A total of 600 Watts. I also checked the performance chart on the Cobra motor page and saw that the actual tested output would be closer to 350 Watts per motor after calculating an efficiency of 80%. This would be a total of 700 Watts and would give me about 175 Watts per pound. (My total weight turned out to be 4lb., not 3lb. as suggested on the box.) On the 4S pack the current would only be 30A per motor, or 60A total. I used Castle Talon 35 Amp ESCs. This turned out to be a very good power system.
The Cobra motors did not fit the aluminum motor mounts supplied so I made new ones from .040″ carbon sheet.
The correct size spinner was hard to find but I finally got them from Ebay. Turns out Ebay has a huge selection of RC parts. Much better than Amazon.
Call the bug man, we have an infestation!
After seeing my Mossie fly, Steve Neu brought out its big brother.
Click the pic for a short video.
By Carl Murphy
This is why my RC airplane has seemingly double the power and duration of yours. Even this unknown, inexpensive, motor turned in enjoyable performance. Getting there required using and evaluating including a motor that burned up, a pending equipment failure motor-controller, a cheap propeller carrier collet that caused vibration, a new propeller carrier collet that didn’t just bolt together, overheating a battery and it required propeller tuning and duty cycle determination to get the best out of it.
All I knew about it was from a tag on the bell, brand Finwing, intended for use on 2S and 3S LiPo (batteries) with a kV from the data sheet on the bell and that it was about the right size to fit the RC airplane. Is it good for anything? As was determined, resoundingly, yes. Most people would be delighted with it. About the power of a sport (20) sized fuel burner on (10)% nitro-methane with a decent muffler for double the duration. That from having watched a similar sized fuel burner at the field right against the USA/Mexico boarder. Sometimes, this time, inexpensive and not all that efficient is still fun. On modern high discharge 3S 3500 mAh LiPos with an APC 9X6 (fixed, not folding) propeller it flew a Reinforced Fun Cub well. Duration was about two thirds of a preferred, lighter, more efficient motor with a folding propeller. Or half the duration at half the net power of a more expensive motor on 4S LiPos. Even more if glided, slope soared or thermaled, something the fuel burners can’t do. Part of that it the better streamlining possible with electric power and an RC pilot who flies coordinated.
But it took a while, twenty flights, to get it sorted out. That is what this article is about. I do not believe reports based on a single flying session where everything is perfect on the first try.
Flying weight about 15 lbs
My PZL_104 Wilga aircraft ARF from Black Horse Models. This aircraft is a STOL civilian plane from Poland. I really liked the uniqueness of this model. I wanted to maintain the appearance of the cowl, so I used a motor designed for sailplanes. It’s specs are 40-30-390k 8S 2200W. The electronics are Spektrum SMART receiver, ESC, batteries and a DX9 transmitter. The pilots are removable and are secured by magnets. Here is a link for more information on the Wilga. https://en.wikipedia.org/wiki/PZL-104_Wilga
Weight 14 lbs
By Wayne Walker, SEFSD
It all started when I was given an old Multiplex AcroMaster pattern plane. I won it because I bought the late John Forester’s two model sailboats. They say never look a gift horse in the mouth, yeah right.
After I got the sailboats sorted out and ready to go sailing, I turned my attention to the AcroMaster as I wanted a rough & ready plane to practice my maneuvers & landings.
I went through it and everything seemed all right, so I found a 3S – 3000 battery for it, and put it in place, it didn’t balance at all, nose too heavy. Then I noticed it had a pretty big motor for that size plane, all the better I thought but it was obviously too heavy & why the plane didn’t balance with the battery in the location designed for it. Moved things around & added 4 ounces of lead to the battery and it now balanced.
Took it out to the field to test fly it. Roll out was good, but as soon as it was airborne it didn’t seem to have good control. I was able to make a 180 from the takeoff, but then it was all over the place! It ended up crashing over by the RotorPlex area. When I was gathering up the pieces, I noticed the right aileron was pulled out of the wing, hmmm probably what caused it to go out of control.
Later back at my shop I glued everything back together with my trusty 30 minute epoxy and paid extra attention to getting the aileron flex hinges glued in with plenty of epoxy to make sure they held in the future. I also had fun gluing the nose pieces back together and wrapping a fiberglass bandage around it all to keep it in place and hopefully straight and sound.
Back to the field to try again. Takeoff was normal & turnaround normal then as I got it about even with me where I was standing all heck broke loose and it was uncontrollable again! And it crashed.
When I was gluing things back together again, I noticed that most of the glue joints had turned brown, I just figured the builder used low grade epoxy or rubber cement. I was also mystified as to why the recently epoxied aileron joins had pulled out again. I asked around and everyone I asked said they thought the epoxy was the best way to glue Multiplex’s Elapor foam together.
Well, it turns out that epoxy & carpenters glue only proved a half-baked bond to Elapor & similar shiny skinned plastics! After getting what I term “Old Wives” tales of which glue to use I found the following on several Multiplex model airplane construction manuals:
From: MULTIPLEX Modellsport GmbH & Co. KG
“This model is not made of Styrofoam™, and it is not possible to glue the material using white glue, polyurethane glues or epoxy; these adhesives only produce a superficial bond which gives way when stressed. Use medium-viscosity cyano-acrylate glue for all joints, preferably our Zacki-ELAPOR®, # 59 2727 – the cyano glue optimized specifically for ELAPOR® particle foam. If you use Zacki-ELAPOR® you will find that you do not need cyano ‘kicker’ or activator for most joints.
However, if you wish to use a different adhesive, and are therefore obliged to use kicker / activator spray, we recommend that you apply the material in the open air as it can be injurious to health. Please be careful when working with any cyano-acrylate adhesive: these glues can harden in seconds, so do not allow them to contact your fingers or other body parts. Wear goggles to protect your eyes!”
In another Adhesives note I found the following advice on technique.
“On one surface spray on Kicker and let dry for several minutes.
On the other surface apply Medium CA as needed.
As the join will set in a very short time align the pieces carefully before letting them touch as there will only be several seconds before the CA hardens making a permanent bond.”
I found that using this procedure results in a 2-3 second flexible time, not really enough to align large pieces of work like an AcroMaster wing panel.
So with all this new information, what did I do? Of course I ran my own tests to see how well these adhesives bond Elapor. I also did a test of Formula 560 Canopy Glue.
Here’s the picture of the test samples I glued together and then 24 hours later tested for strength. All samples were on virgin Elapor foam.
I tested both “Plain”, no preparation, and Prepped with alcohol and then sanding to remove the gloss on the surface of the foam.
The Canopy Glue 560 was the weakest with only a small pressure to part the two pieces.
Using Odorless CA was almost as weak as the Canopy glue.
The high quality Epoxy joined pieces were next in strength, 1-3 pounds of pressure to break the bond.
I didn’t test White, Carpenter’s or Ambroid glues as these are seldom used in modern model construction.
The Medium CA plain & prepped samples I was not able to break apart, but my arthritic hands were only able to apply about 5-10 pounds of force to the joins, this is probably equivalent to a hard crash to the joined pieces.
When gluing Multiplex Elapor and similar shinny skinned foam use Med CA with or without Kicker, it will be the strongest join available, and no prep is needed to make a strong joint.
When gluing Styrofoam pieces use Odorless or Foam Safe CA glue, or epoxy.
As far as Hot Gun Glue goes, I’ve bought several Chinese models that have them, but don’t recommend the technique.
As an aside, I found that Du-Bro & other hardware suppliers have discontinued the line of hard plastic hinges and instead recommend the Fiberglass mat type of hinge material. I’ve now substituted this for all my flex hinges.
By Carl Murphy
One Airplane, Two Batteries, an Hour of Carefree Flying
(0) to (750) Feet At a Count Of Ten (5S) or Thirteen (4S) or Fifteen (3S)
This is an instruction by examples of electric propulsion choices for a four foot wingspan, molded from impact resisting foam, reinforced, light wing loading, semi-scale RC Piper Cub. Chronicled are testing, things gone right and wrong, and, RC flying as a whole experience. From light weight one and an eighth inch diameter outrunners, light to medium (37) mm diameter outrunners through geared competition inrunners, four combinations were selected as optimal. From relaxed to outrageous, flight times start at twenty-five minutes on just the motor and battery. Altitude gain at maximum climb for count of ten ranges from three hundred to seven hundred and fifty feet, glide back down from a seven to one ratio to fifteen to one.
Tuning Is Worth It
Where I started RC flying in Orange County, CA, back in the mid 1990s it was next to the current F5B world champion and six other current or former thermal, slope soaring and pylon RC pilots. At San Diego’s Mission Bay my company includes a former F5B world champion who manufactures the worlds best RC racing motors plus several more national and international ranking F5B, F5D and F3A precision aerobatics RC pilots. As a friend in low places (I gave up my Piper Pacer at the start of the second great depression, for ten years I was almost, but not quite, broke) though the experience with getting a RC airplane set up right was not lost on me. Significance; Nobody has ever seen a Fun Cub fly this well, when I loan my RC airplanes to other pilots they don’t get as much performance or duration. Part of that is having flown enough to be “one” with this airframe.
This article is paired with articles about The Mentor Propulsion, a larger and heavier airframe and an article about The Cost of Flight, Outrunners verses Inrunners. Continue reading
By Bob Stinson
64th Aggressor Squadron, Callie Graphics and an Eflite F-16
By Otto Dieffenbach
This is a project I started on after the first of the year. The plane is Lassi Nurila’s version of the Sensation F3a pattern competition bipe. The design originated in Germany around 2012 and has captured many titles in world competition. Last year Lassi flew his version to 5th in the World Championships. I started flying modern pattern with Bruce Brown once a week with a used 2 meter plane. I realized that I enjoyed the flying as much as classic pattern and decided to up my game. Lassi was kind enough to work with me from Finland. He layer up a fuse for me and I picked it up at LAX. I had the wing/stab cores cut by Eureka and Don did a fine job. I began actual building in mid August and maidened on the 12th of October. It flies very much like a 3D indoor foamy. Effortless knife edge and tracks beautifully.
By Steve Belknap
About 20 years ago I put a cradle on my Sig Kadet Sr. to carry gliders aloft and release them. Recently I pulled out the cradle and dusted it off. Frank G. had a freshly made Goldberg Wanderer he had not yet flown. So I rubber banded everything onto the Kadet once more. Everything worked perfectly. So far I have launched his glider 5 times. On the last flight Frank measured the radius of one of the light standards using the leading edge of the glider. All fixed now and ready to fly again.
Some of the members who were around then might remember my initial attempts to use this launch cradle. They might remember when I launched a glider and the rubber bands released on only one glider wing. The other wing stayed attached to the cradle. It got ugly real quick. Finally, the glider separated from the cradle. The rubber bands did not let go but the glider snapped off the upper part of one side of the cradle. Everything landed OK and the cradle was modified to prevent the rubber bands from not releasing.
Click the pic for a short video:
By Bob Kreutzer
Locked down, but not out.
Last issue I showed my “lock down project”. A good friend lent me His Ender 2 3D printer. At ~$200 it is an absolutely great deal on an entry level 3D printer. I can recommend it. I wanted to add a full ordinance load onto my MQ-9 project. So I jumped in with both feet and learned a new skill. Like most things, once you get the hang of it, well it becomes pretty easy. Basically there are 3 steps.
1: Obtain an STL file of what you want to print.
2: Download a slicing program (more on that)
3: Put your sliced STL file into the printer and press the on button.
OK. An STL file is to a 3D printer as a PDF file is to a regular printer. Nothing more.
A slicing program (I used CURA and do recommend it highly) allows you to place the project in the proper place on the 3D printer bed. It also allows you to size it to your needs. You press the SLICE button and everything magically happens. Then tell it to copy onto a SD card.
Take the SD card and insert it into the 3D printer. Scroll through like, 2- 3 menu options and press “PRINT”. That’s pretty much it.
So here is what I did:
I finally finished the 1.9m Avanti XS (120mm EDF on 12S). Everything is ready to go except for me – I haven’t flown in two months. I thought these pilots needed kindergarten-level controls, so Bert has buttons for “Fly” and “Land.” (I don’t know why most cockpits are more complex than this, because that pretty much covers 100% of what an airplane needs to do.) Ernie is a bit more negative in his outlook.
Setting up your T-28 to race by Steve Neu.
The most important thing that many people miss when starting to race RC planes is that going fast is nothing without control! The FMS T-28 is a small plane and setting it up to race IS very different than for your basic sport flying. Getting the CG and control throws dialed in are key to getting the plane to “go fast and turn left” and keep in control. As a racer running at full throttle— the elevator and aileron travels needed are minimal. A properly setup T-28 will actually be easy to fly with only small control deflections.
The control throws suggested in the FMS instructions are intended for a plane flying much slower on a 2S battery. We are flying much faster with 3S. Here are the control deflections I have on my plane:
Ailerons: 6mm up 6mm down
Elevator: 3mm up, 3mm down
Rudder: 6mm left, 6mm right
CG measured from edge of wing at fuselage opening 71-72 mm—see picture below.
I like about 30-40% expo on both aileron and elevator—helps make the plane less sensitive around center making it easier to do fine adjustments to the plane’s track. A little nose heavy helps make the plane positively stable in pitch and the elevator less sensitive but the recommended CG in the FMS instructions is too nose heavy for my taste. Too rearward CG locations will make the plane neutral in pitch stability or even negative which will make it more difficult to find a stable track down the course. The trade offs in moving the GC is stability vs turning ability with the aft CG setup being able to turn more quickly. You need to be careful with the CG and elevator throws in that if you get too aggressive the plane will tend to snap roll in tight turns.
If you find the racing setting a little too mild for take off/landing and general sport flying I suggest setting up a dual rate switch so you can easily swap from control rate one to another.
Some of you did not read my previous article regarding the “AD” for the nose wheel strut—I learned the hard way that on our rough field the stock strut puts the nose wheel too close to the prop which will result in props getting busted when the blade hits the nose wheel rubber. The fix is easy—just turn the nose wheel around (be sure to put a flat on the shaft on the opposite side!).
Our first T-28 race will be in July!