Skymasters Newsletter:
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SkyWriter
Chartered Club #970
Skymasters R/C Club Newsletter
- April 1998
See Skymasters on the Web at www.geocities.com/~skymasters
President's Message
Hi All,
Well, last month I wrote how wonderful it was to be flying in February, and was looking forward to an extended flying season. Mother Nature again reminded me who was the boss, as I sit here in 15 degree weather in mid March where spring was supposed to be. - Oh well.
Our real "rent" for the year is almost upon us, and that is the Bald Mountain involvement day, which I think will not have occurred when you read this. April 18 is the scheduled day, and I again want to ask that you attend if at all possible. There is much work to be done, and all capabilities are welcome. Not all tasks are strenuous or involve heavy lifting. Please come and sign in even if for a few hours on Saturday. The place to go is the Greenshield road entrance to the state park, which is on the East side (for those of you familiar with the summer pilot meetings, the Greenshield entrance is right by Brewski's!). Our turnout is the best field saving thing we do. The world is full of people who talk and don't act, we demonstrate the latter when we show up en-mass!
We are actually progressing on the second field, thanks in large part to club member Chet Brady. Chet has relentlessly pursued the Metro Parks, and has spearheaded initial efforts into a site in the Stony creek area. Greg Cardillo and yours truly represented Skymasters at the first informational gathering where the initial proposal to the metro parks was formulated. The initial pass is now in the Metro parks hands. We have not as yet formulated many of the details out, primarily because we need input back from the Metro parks on what they will do for us and what we have to pick up ourselves. We currently envision the involved clubs picking up start up costs, with the metro parks handling maintenance (mowing in particular). The facility will be set up as a second field for all clubs, per Metro park requirements, and it is very well suited for R/C usage. Greg Cardillo represented Skymasters on a field trip to the site and came away enthused about the opportunity. (yup! - ed.) There are not many more details to report for now, other than your BOD is working this issue closely. Please feel free to send me comments, or make them in person.
As true spring nears, I always find my excitement growing and a smile on my face as I anticipate the season's first crash, er, flight of the new ship I always seem to take all winter building. Things are getting bad when it takes me over 3 calendar months to finish a plane I bought in the bones that only needed radio and engine to be fitted before covering ! This time is also one of the easier times to slip up on proper care and building in anxious moments to get the ship done before that mystical first flying opportunity. It is difficult, but take your time here, do the extra sanding, double check the hinges, verify the radio and everything else that is easy to overlook. I have sent a ship or two to an early grave because I did not heed this very same advise. I've finally wised up to let my ships come out to fly two weeks later than hoped, but in much better condition (safety and appearance wise!).
Toledo nears and I am filling my wallet in anticipation of buying a hot 40 size ship, or a ship sans motor for one of my lonely 90 four strokes. As usually happens though, I wind up buying something totally unplanned and that's part of the fun. There is a large contingent of us going down on the first day, Friday April 3, early in the morning to concentrate the entire day on the swap meet. We also stay over night to go back to the show on Saturday to spend on the main floor admiring the show entries and talking to the manufacturers. If you would like to join our band of gypsies, give me a jingle. We will leave pretty early Friday morning (before 7:00AM) to make the swap meet. I would advise going to this show if even only for a day.
I'll give our poor newsletter editor a break this month and cut off my rambling so I can begin my next verbose article on horsepower ratings on our hobby -
Hope your balsa stays where it belongs !
Joe Finkelstine
From the Editor…
Once again a full newsletter from your 'poor newsletter editor' (thanks Joe!) Thanks again to Joe Finkelstine for contributing Part 2 of his 'series' on airfoils. Anyone is welcome to contribute ideas/articles for the newsletter. I enjoy having the problem of too much material! I haven't had to use any of my web sources yet this year.
The 'For Sale' section is in search of items to sell. It will return as soon as I receive input.
As always, send any input to me either to my address (on back cover) or email to GMCardillo@misi.net, or of course see me at a meeting.
We have some interesting programs coming up for our April meetings. See details inside!
Meeting Minutes
March 11, 1998 Meeting at Larson Middle School
· Minutes from previous meeting were read and accepted.
· Treasurers report - $12,159.29 in the check book.
PRESENTATION
Joe Finkelstine did a presentation on the electronic portion of our planes (transmitters, receivers, servos, wires, antenna). He spoke about AM, FM, and PCM transmitters; amplitude; frequency; gadgets and other info that this Secretary could not keep up with. Thanks Joe!
SHOW AND TELL
Joseph Rubinstein - Joseph brought in an Electric ARF glider, sold by the SR battery folks. It had carbon fiber components and appeared to be very well constructed. (Joe won the gift certificate).
Al Post - Al displayed a ARF Dynaflite "Butterfly" which was powered by an OS15. It was covered in Tower covering and had a weight of 3 lbs. 12 oz.
Harold Reuter - Harold brought along a Pica Rapier, which was powered by an OS61.
Herb Schiebold - Herb displayed his Florio Flyer 40 which was powered by a Thunder Tiger 40.
Joe Hass - Joe showed us a Pattern Bat with Ultracoat covering, powered by an OS10 and used a rudder. Also, he showed a DC3 kit from Czechoslovakia which arrived without plans (good luck Joe).
Greg Brausa - Greg displayed a Trainer 2000, it was powered by a Thunder Tiger 42 and weighed in at 4.5 lbs.
Jack Fleming - Jack brought in a sample of the first radio controlled rudder system. It was able to move from a neutral position to either full right or left.
OLD BUSINESS
The club has been looking into the possibility of obtaining a multi-club shared field at a Metro Park.
Bald Mountain involvement day is April 18, 1998. The club is looking for group leaders to head up projects. Those interested should speak to an officer. Attendees at involvement day will have to chance to win club offered prizes.
The Swap Shop took in roughly $645.00 profit.
Gary Weaks spoke about the Virtual Library (book sharing library) and provided a list of the available books.
NEW BUSINESS
The Toledo Show will be held on April 3, 4 & 5
Upcoming presentations:
March 25th - Al McGee - "Fiberglassing"
April 8th - Michael Morton of Morton Helicopters (bring in your helicopters)
April 22nd - Bill Leppard and Darrell Watts - "Multi Engine"
May 13th - The AMR Company will do a presentation on first aid.
(note - see some schedule changes for upcoming programs elsewhere in this issue - ed.)
Events of the Last Month
Swap shop report
The weather on Ash Wednesday the 25th February was brilliant, it felt more like April than February - it was certainly better than last year when we had some quite nasty snow when we were busy unloading cars. Perhaps it was the weather, perhaps it was Ash Wednesday or perhaps everyone was "swap-shopped" out. Either way our attendance was down with only 258 people joining us - last year it was 307. Interestingly, with only 258 people, it still appeared that the car park was overflowing ! The good point about a lower attendance was that the isles weren't quite as crowded and there wasn't such a massive queue for the hot dogs.
Once again, splitting the evening into lots of 30 minute work 'slots' seemed to help out - it helped me in getting people signed-up ready to work and it shared the load. I wish to thank everyone who helped during the evening especially Bill Dzure for organizing the kitchen. All of your help made the whole event run much smoother and made it easier for everyone. I should mention Doug Riley Jr. who just made it to the school in time to help clean up and tidy the room! Thanks to you all.
We had two raffles, a 50/50 drawing and a door prize and we gave away lots of goodies ! Ian Aldcorn won the door prize (House of Balsa P51), Wade Wiley the main raffle (Goldberg Ultimate bipe) and John Verbruggen the 50/50. Hopefully some of you went away with raffle prizes too. I have to mention that we did receive help with the prizes from the following organizations (please remember them when making purchases):
Bob Smith Industries
Dixie Electronics (which is no more)
Joe's Hobby Centers
NorthEast Screen Graphics
R/C Modeller
R/C Report
Riders Hobby Stores
Tower Hobbies
Windsor Propeller
Everything seemed to run quite smoothly with no major hick-ups or problems and the free hot-dogs for all you die-hards at the end were a real hit. I trust that you all had some fun, perhaps you snagged a bargain or even sold that old stuff (spelt l-e-m-o-n ?) Either way, for all of you who helped - thanks; for all of you who spent some money - thanks for making the event a success. Oh yeah, all of you also raised some money for the club.
Gary Walling
PS How cheap can an swap shop attendee be ? Well I couldn't quite believe it when several people wanted to walk past me into the hall without paying the $3 entry fee. Plonkers!
Gary Walling announces yet another raffle winner!
Tables, tables and more tables packed with good stuff!
(Buy anything Matt???)
Lot's of satisfied customers!
Upcoming Programs/Events
Friday-Sunday, April 3,4,5: Toledo 98, Seagate Centre, Toledo, OH
Wednesday, April 8*: Skymasters Meeting, Larson Middle School - John Myers, WWII Fighter Pilot
Saturday, April 18*: Bald Mountain Involvement Day, Bald Mountain Park Headquarters
Wednesday, April 22*: Skymasters Meeting, Larson Middle School - Mike Morton, Morton Helicopters
Saturday/Sunday, May 2-3: Q-500 standard/expert pylon races, Signal Seekers' field, Westland
Wednesday, May 13*: Skymasters Meeting, Larson Middle School - Multi Engine Program
Saturday, May 16: Seven Lakes Spring Float Fly, Seven Lakes State Park
Sunday, May 17: Bald Mountain Float Fly, Bald Mountain Recreation Area Trout Lake
Friday-Sunday, May 22-24: Frankenmuth Aeromodelers Club Memorial Day Weekend Camp Out & Fly-In
Wednesday, May 27*: Skymasters Meeting, Larson Middle School - Monokoting with Vince Pettke
Monday, May 25: Yankee Air Force Memorial Day Open House, YAF Museum, Willow Run
Saturday/Sunday, May 30-31: Greater Detroit Soaring & Hiking Society Sailplane Weekend, Addison Oaks
Sunday, May 31: Chet Brady Memorial Mammoth Fly-In, Scripps Road Field
*See additional information for these events in this issue of Skywriter!
Event information from mailings received, Model Aviation Events Calendar and Michigan RC Flying Times
Skymasters Events
We have some very interesting programs over the next two months, as well as our annual Involvement Day.
April 8, 1998 Skymasters Meeting - Larson Middle School. An evening with John Myers, a noted WWII fighter pilot. John will be interviewed by Pete Waters. John was flying at the age of 19 in a 40 hp Taylorcraft. He flew Spitfires in the African Theater with Bob Hoover in the 52nd Fighter Squadron. John was a POW for 14 months with Bob Hoover. Come and hear what is sure to be an interesting conversation. Bring in a warbird for Show & Tell tonight!
April 18, 1998 Bald Mountain Involvement Day - Bald Mountain Park Headquarters. A great start to Spring. Come out and volunteer to help our park prepare for the summer season. There are light jobs, heavy jobs and everything in between. Steve Fredericks is coordinating this once again. Please come out and support this important event!!! There is something for everyone to do. We have some nice prizes to give away to those that come out, and food and drink is provided.
April 22, 1998 Skymasters Meeting - Larson Middle School. Mike Morton, a Certified Flight Instructor with Morton Helicopters will be joining us for the evening. Mike is based at the Big Beaver Airport in Troy. Come join us and learn about the 'full scale' helicopters. For those helicopter pilots in the club (or other visitors that join us), bring one or more of your helicopters with you!
Fuel Buy
Our annual fuel buy is here! Morgan Fuels Cool Power 10% will again be purchased in drums. Cost is $9.50 per gallon for the bulk fuel (provide your own container!). For those looking for higher nitro, 15% and Four Stroke fuel will be available for $11.00 per gallon pre-packaged. Paul Shurtliff has the signup forms. Please signup by the end of April! Thanks to Al McGee for coordinating the purchase once again.
Airfoils by Joe Finkelstine
In part 1 of this long winded newsletter article, I discussed some fundamental terms and concepts regarding airfoils, such as chord, symmetrical, etc. I want to elaborate further on all the airfoils in our ships.
Besides the wing ribs, several airfoils exist on our ships. These include the fin and rudder, the horizontal stabilizer and elevator, the prop, and even the fuse (if we just slightly stretch our definition). Lets continue here with the typically biggest flying surface - the wing.
The wing, being composed of all the wonderful ribs we talked about in part1, also has lifting and stability issues associated with it separate from any individual rib that makes it up. A couple of fundamental characteristics are span, area, aspect ratio, and planform, (Dihedral angle is also important, but that has to wait until I get around to deciding if part 3 - stability - ever gets written!). Span is simply how long the wing measures from wing tip to wing tip. In our hobby, "mammoth" scale is generally thought to start on ships that have a wing span of 80" for mono or 60" span for bipes (or ¼ scale or bigger for you perfectionists out there!). To me personally, wing span mainly shows up in me determining if the plane will fit it my car! Area is the 2 dimensional area of the wing and can be approximated by multiplying average chord of the wing and the span. Wing area is an important metric because it can be used to calculate several flight characteristics quickly. A common metric is the ships wing loading, which is the total weight of our plane divided by the wing area. Generally, trainers have the lightest wing loading and scale ships (particularly WW1) have the highest. Wing area is also used to calculate total lifting force of a wing and other performance calculations. Aspect ratio is one of the more interesting pieces of a wing and the mathematical relationship is defined, in simplest form, as the span of a wing divided by average chord. Aspect ratio shows up in all sorts of performance calculations and in general, the higher the aspect ratio, the more efficient the wing will be for a constant area. This fact is one reason you see the RC sailplanes with long skinny wings - they are trying to get the highest efficiency they can as gravity and thermals are their only energy supplies. The limiting factor in high aspect ratio wings often is in mechanical rigidity and transportation issues. Our sport type ships have aspect ratios between 5 and 10, with some wild fun fly ships apparently approaching 1 for those short fat wings on Popsicle sticks. Planform is the shape of the wing from a vantage point of a top view. After a few pages of math that would bore you all to pieces, I could also demonstrate that wing planform also affects efficiency, and also affects stall characteristics. The theoretically most efficient planform for a wing is an elliptical shape. Practicality limits us in RC though as an elliptical wing is full of compound curves, that are well out of the skill set of many builders (especially this one!). Indeed, the challenges of manufacturing a truly elliptical wing were so great that only 2 full scale ships that I know of had them - The Spitfire and the P-47. A good compromise to an elliptical wing is the semi-tapered wing, which shows up commonly on full scale Cessna's, etc. It only gives up a small bit to the elliptical wing in efficiency coupled to big gains in ease of building. We also have single and double taper wings common in our hobby, which affect wing efficiency. Building a tapered wing is a challenge in our hobby, but one that most can tackle after a few ships.
Besides the primary lifting force for our entire ship, we also ask the wing to generate rolling moments. This is accomplished via our ailerons. Consider when a command is given to roll the ship. We desire to lift one half of the wing more than the other half to create a net rolling moment on the ship. The aileron on the wing side we want to raise lowers, increasing camber for that side of the wing, which if you are still awake, you know will increase that wing sides lift. At the same time we deflect the opposite aileron up decreasing the other wing half's lift, which assists our roll. You will occasionally see one more set of control surfaces in R/C (although much more common on full scale) on the wing and they are called flaps. Like the aileron, each wing half gets a flap, but the similarity ends there. Both flaps on a wing deflect in the same direction. When deflected down less than 20-30 degrees (typically) , the flaps can add significant lift (again by increasing camber) and shorten takeoff runs, etc. When flaps are deflected more, they begin to add more drag than lift and can be used to help slow an aircraft for landing. For those that use a computer radio, a neat trick for those slippery fast ships is also to have the flaps and/or aileron's deflect up on landing approach, which actually decreases wing lift - helping those floaters find tera-firma again before it smacks the weeds off the end!
Some important things about our wings in R/C
1) The most important thing to do is to build your wing true, rigid, and light. All kinds of odd behavior can result from warped wings and it can drive student and instructor nuts trying to trim that nonsense out. If your building surface is warped, so shall ye sow the wing !
2) Pay attention to the designers leading edge template - If you just wily nily sand and forget it, you will be rewarded with some cheek tightening moments when you stall the ship. Typically, the plans show a leading edge shape - cut the thing out and use it as a template.
3) You should always reinforce the wing center joint if the wing is built in halves and then permanently joined. - This is one area where I cringe when I see some of the cheaper ARF's come to the field with no fiberglass center reinforcement. Omit this step, and you should plan on having your plane show up in one of those RC crash videos we all love to watch - you know the one with the folding wings!
Next, for your continued enjoyment, we move to the typically next largest set of lifting surfaces, the tail feathers (elevator, rudder, stab , etc.).
The tail feathers main job is to provide lift to either change a ships attitude (or maintain current attitude). For example, the rudder is used to provide a yawing moment (like in a spin), or used to counteract right engine torque on high angle of attack motion. The tail feathers provide a smaller lifting moment than the wing, but are designed to upset the delicate balance up front under our control.
The elevator and horizontal stabilizer pair form an airfoil and the elevator , via our servo(s) and control horn(s), move up and down to change the camber of the pair. The lift change created by the elevator coupled with its distance from the plane's C.G. creates a pitching moment of the ship about the C.G. Similarly, the fin and rudder make up an airfoil, with the rudder acting as the camber master. The primary difference is obviously the rudder/fin pair is aligned to do its yanking and pulling in the yaw axis. A few interesting things to note about our tail feather friends:
1) Often, the stationary pieces of our tail feathers are slabs of balsa, or built up stick construction. Many times, lazy builders like me just round the front end and move on to more important things - this is a bad idea. The reason our instruction manuals plead with us to sand the tail feather pairs into an airfoil shape is to keep the lift coefficient vs. angle of attack curve (remember those funny graphs in part 1?) reasonably stable and predictable. Even a barn door provides lift but the lift behavior near stall of this type of shape is very unpredictable. If the lift of one of the tail feather pairs suddenly and rapidly went to zero for example, it would make for some rather puckered lips on the pilot. The pattern guys are quite careful about their tail feather airfoil shape for this reason, and some even build up the tailfeathers with ribs and a spar, just like the wing.
2) Just like the wing, we can cause the airflow to separate over the tail feathers and cause them to stall. If any of you remember the Aeromaster I, ahem, used to fly, I had the pleasure of watching the elevator stall any time I pulled more than ¾ stick. This caused frequent hammerhead turns (Indeed, its last hammerhead was initiated about 1 inch above the ground causing me to suddenly have my Saito 90 available for my next project). There is a limit on how much we can have the moveable surfaces on our tail feathers transit, and stalling them is one constraint (mechanical constraints also occur here!). I have seen more ships get into trouble on maiden flights because of the wonderful behavior of making deflections bigger than designer recommendations (I am guilty as charged on this one - in fact I am a repeat offender!)
3) When scale ships are designed, it is quite common for the tail feathers to be enlarged from full scale. One thing we cannot scale in R/C is the air. In general, airfoils become less efficient the smaller the chord (other things being held constant). The problem we face in scaling full size ships is that the moment (Amount of Lift * distance from C.G) we need would be to small to give needed control. Two choices are available. 1 - make the tail feathers farther away from the C.G. - and totally wreck the scale outlines, or increase the size of the tail feathers. Classic pattern ships use long distances from the C.G. , because they are not scale, and because they want strong tail moments. Likewise, the aerobatic masters of T.O.C. increase the tail feathers considerably (I believe they are allowed a 10% deviation rule) to create the huge tail moments needed for the wild tumbling we like to watch.
Our props as airfoils:
The props we love to spin and cut our fingers on are actually airfoils as well. The 2 main parameters we use to specify our props are diameter and pitch. For example a 10-7 prop has a 10" diameter , with a 7 inch pitch. The 10" diameter part is pretty much self evident (if you don't understand that one, perhaps you need to change hobbies!), but the pitch part could use a little explanation. Theoretically, pitch refers to how far a prop would travel in 1 revolution if no losses or slippage occurs. So using our 10-7 prop as an example, spinning our prop exactly 1 revolution would make a cylinder 10" in diameter and have a height of 7" in that theoretical stuff that unfortunately we can't fly in. The airfoil shape of our prop changes shape as you move out from the hub to the tip. One of the primary reasons for this is the fact that the blade near the prop has slower linear speed than near the tip (for those of us old enough to remember 33-1/3 records, remember how you could put a penny near the hub and it would stay there, but the one near the edge would fall off and hit your sister in the eye and get you in trouble? - same thing here). The airfoil shape changes to keep the lift somewhat equal across the blade. Some important things to remember about props that we flight instructors always get asked about:
1) There is no single "best prop" for any engine, this is one reason engine manufacturers suggest a range of prop diameters and pitches. Generally, you can try props in the suggested range and even a few outside the recommended range to accomplish different performance desired. Keep in mind that when doing this it is vital not to "underprop" the motor, which would cause it to over-rev at full throttle (unless you want to become our next meeting engine tear down and rebuild presenter). The other end of the scale of "over propping" shows up by lugging the engine, which also will soon add to your skills of engine rebuilds. Always keep in mind that one thing that must always be observed is the RPM range that the engine will effectively work in and this ALWAYS must be honored.
2) Given that you just read #1 above and will stay within recommended rpm range, what props do you choose ? - That depends on what plane and method of flying you do, and a few other things as well. For example, when I prop my ships I like fast acceleration rather than top end speed. Prop Diameter has most effect on acceleration and pitch has most effect on speed. When I prop most of my planes, I usually opt for the largest practical diameter and let the pitch go to whatever keeps the engine rpm where I need it - The "best" prop for me would not be best for a flyer who wants his ship to fly fast at top end, even with the exact same engine.
3) Our props are often major contributors to the noise of our planes. Often the type of prop can drastically lower sound (APC props are good for this), as well as propping to lower top end rpm (again staying away from lugging the engine). Our emitted noise levels are highly dependent on rpm, so propping for lower top end rpm can often drop you a few dB's.
4) The composite props are more dangerous to use than the wood variety. The positives of composite props are efficiency, lower noise and the sturdiness (I usually nose in at least one landing a flying session, and my APC prop just gets a little dirty - whereas a wooden prop would be in pieces). One of the major drawbacks of this prop is its ability to cut through the careless body parts put in its path without hesitation. One of the major advantages of a wood prop is that if your gonna put your finger in the way, often times the wood prop will break before it makes a mess of your hand. Wood props are also easier to obtain in unusual sizes, but they sure do break easy.
The fuse as a lifting body ????
Actually , the fuse of our ships is a lifting surface even though it usually has a box shape. To prove my point watch a plane in knife edge. Take my word on this one, the wing , being vertical is not contributing much to keeping our plane in the air. The rudder/fin and the fuse itself are helping here (also is the over powered motor that I always put in my planes!). One of the interesting things about biplanes is the inter-wing supports. If you take the time to make these a good airfoil shape, you could significantly help the bipe in knife edge (and reduce drag as well!) Take the time to at least make your fuse smooth and straight and it will help you out as a part time employee in the lift department!
Skymasters Information
Skymasters field is located within the Bald Mountain State Park (see map). State Park Permits are required and can be obtained from the Park Headquarters located on Greenshield Road or at club events. Flying is permitted from 10 AM to 8 PM. The noise limit for 1998 is 95dB at 10 feet - this noise rule is strictly enforced.
Wednesday evenings during the summer is Student Night and there are usually instructors around all afternoon. Student night is also 'pot luck' buffet night so that you can fly-n-feed (though not usually at the same time). Students are encouraged on other days and weekends. It is a great idea to come on Wednesday, meet the Instructors and arrange for more instruction time together. Our Chief Flight Instructor is Pete Foss. Assistant Chief Flight Instructor is Graham Overton.
From June to August, Club Meetings are held at the field on the first Saturday of the month at 12 Noon - a great chance to fly and gossip too! Winter meetings (September to May) are held at Larson Middle School (on Long Lake just east of John R - see map) on the second and fourth Wednesday of the month at 7:30 PM. Show and Tell, coffee and donuts, and model-speak are the order of the evening. Come along - they are fun.
The Skywriter newsletter is sent to all members, local hobby shops and other local R/C clubs. Any and all contributions are welcome, please pass any articles to the Editor. If you know of anyone who may be interested in our hobby (friend, relative, neighbor, colleague or acquaintance) - please give them a copy of this newsletter or a copy of an AMA magazine - it may spark their interest and get them into our hobby!
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