tomclark

I'm a bit of a dinosaur and I'm not afraid to admit it. No, I'm not that old, but been flying since the early 70s, and just about to finish up model number 88. Over the years ten of them have been kits, but all the rest are scratch built. Every few years it is fun to build a kit to see if anything has improved, or to see if any worthwhile new techniques have been developed. Usually not…


I just like doing things my way, building strong but light, and making sure the construction will last for at least a thousand flights - or until I get tired of the plane. And by the way, most of my flights contain 5 to 10 touch and goes, so the landing gear has to be built to take it.


Part of being a dinosaur is the RC forums. I never ventured near until last spring. Sorry it took so long as the last year has been fun chatting with other builders, and having a good laugh reading about how all the builders are gone because all the ARFs killed them. Well, sorry to read I'm gone and didn't know it. Been having a ball, and have built five planes in the last year, and still have a couple of more planed.


One of the kits I built in the past was a Top Flight Contender. The kit has a 53" wingspan and will take a 40-60 engine; but the truth is they are quite nose heavy with a 60. Today a modern 55 would be excellent. The kit is still available and has been redesigned and to make it lighter and quicker to build. However, when you scratch build something there is no reason that you have to build it the original size. You are free to build your plane any size you wish, right? And I do. I like bigger planes - usually with 6-8' wingspans. I usually use basically the same construction on all of them. It is very light, very quick to build, very strong, and very cheap. I like cheap! Most of my builds cost well under $100 for balsa, ply, glue, and covering. My Gallery shows many of my planes, and my blog goes into a bit more detail.


Warning - If you like beautifully built scale airplanes, stop reading now and go somewhere else. My planes are not beautiful, but they fly fantastic, and that is what I am looking for. I love the building time in the shop, all the way from deciding what to build next, and what size to build it, to drawing a crude sketch for my plan, to cutting up the parts, to covering, and finally installing the radio and getting ready for the first test flight.


My last scratch built thread here on Universe was a 76" Goldberg Tiger last June. This thread is going to be a bit unusual as the plane is almost finished. I just have to fit and install the canopy and it is ready to test fly. Many photos were taken along the way and they should be self-explanatory. Happy to answer and questions, and glad to hear your comments as we go along.


Specs of this build: Span 72". Length 68". Area 1260 sq. in. Weight 6.6 lbs. Wing Loading 13 ounces/sq. ft. Power: ASP 1.08. Big loops, giant Cuban 8s, and out of sight vertical will not be a problem…

The little drawing shows what the plane is supposed to look like. I make a rough sketch to have a place to write down dimensions, and then draw out a full size outline of the plane to build on.

tomclark

Contenders have been around for 40 years now, so I bet many of you guys have built and flown one. Ever think of build one with an 80" or 100" wingspan? I have a bunch of planes that size, and at the moment the plan is to build some closer to 6' spans so they won't take so much power. In the first photo above you can see a low-wing sport plane in the background on my workbench. It has an 82" span and is powered by an OS 1.08. That plane weighs 10-11 pounds, and the new Contender weighs 6.6 lbs. with the same engine. I bet the test flight will be exciting.

I just cut out some balsa parts, lay them in place, and start gluing sticks. The location of the vertical sticks are just eyeballed in place. There really is no need to get fancy. Formers? Don't use them except the firewall.

Once the first side is built, it's turned over and the second side built on top of it.

For a motor mount two pieces of 1/4" ply are glued together. They work great and last forever. Very solid mounts with no vibration. Also costs maybe $0.50 worth of wood.

tomclark

When building a stick aircraft like this, I find it fun to just figure out the parts as they are needed, and change any of the original design to make building easier. Also, change anything you wish. After all, does it really matter if the fuselage is 3" wide or 5" wide? It's not rocket science.

The biggest change to this model from the original is the elevator and rudder servos will be mounted in the rear to keep the linkage stiff as possible. And with that rearward change is the CG will be moved rearward, it might be a good idea to move the engine an inch farther forward.

To keep construction as easy as possible, I like to build the fuel tank in when there is easy access to the compartment. I glue the foam to the supports with silicon glue, and also seal where the fuel line passes through the firewall with the silicon. Hatches? Don't use them. If one is ever needed it can be added with an exacto knife in a few seconds, the repairs made, and then glued back in and recovered, all in less time than it takes to build a hatch in the first place. With no hatch there is no place for fuel to leak in and soak the structure. Silly, eh? So far I have had to remove a fuel tank once in 40 years, so I guess it works for me. If you keep the centerline of the fuel tank in line with the needle valve in the carburetor you will not have any fuel draw problems.

tomclark

So many of today's airplanes are designed with an inverted engine. I did it twice and will never have an inverted engine again. Nothing but problems. Watch around your club field and see that most of the planes with inverted glow engines are the ones deadsticking the most.

Years ago it was normal to sheet tail surfaces on high powered planes. Then some brave guy just left off the sheeting and covered the surfaces. Surprise, it works. Notice on the plans that the original design had solid balsa surfaces on the elevator, rudder, and fins. I just left everything open. You won't believe what the finished weight of the structure is.

By using little balsa the plane comes out very light. My sticks are ripped on a bandsaw so you can make them any size you wish. The tail surfaces and flap and ailerons are all 3/8" thick.

tomclark

My building table is 40x80 to fit the size of planes I like to build. The top surface is 24x48 ceiling tiles 5/8 thick. The pretty side is down, and they are firm enough to provide a good surface to stick pins into. These tiles are cheap and still my favorite building surface.

The original airfoil on the Contender design is symmetrical and about 20% thick - similar to the Kaos airfoil. Many years ago thick high drag airfoils were very popular for some reason. I have come to like slightly thinner airfoils as my favorite, usually in the 14-16% range, with the high point at 38 percent back. That seems to be just right for the smooth flying aerobatic aircraft that are my favorite. I would like the Contender to be a fairly fast airplane with unlimited vertical, so there is no reason to use a high-drag airfoil. Today's computer radios have revolutionized how we can fly and the controls we have available. Flying planes with flaps makes it super easy to slow down for landings, without penalizing the rest of the flight.

To explain: The thickest part of the airfoil is 38% back from the leading edge. The cord on this wing is 15.5" from leading edge to the front of the ailerons and flap, and I choose a 14% airfoil. That means at the thickest part of the wing it is 14% of the cord, or 2.17 thick.

Notice carefully the stack of ribs. By laying a straight edge along the top of the back part of the airfoil there is a slight curve. Along the bottom it is flat. I can't tell you how much easier it is to build the wing flat on the workbench compared to using a jig. The whole stack of ribs were cut on the bandsaw in a few minutes. Even the slots for the hardwood spars are cut at the same time. I like two sets of spars on larger wings for strength.

The leading edge of the wing is 1/2 balsa. It is quickly carved down close to shape and sanded with long sanding blocks to shape. Too much work for some? To me it is fun and all part of the joy of building…

Wings with sheeting on the front and back and cap strips are far stronger than bare ribs, and make for a stiffer wing.

Instead of using a lot of balsa, I simply cut a sheet in two, and use part of the front and part on the back. All the benefits of a D-Tube wing using half the sheeting.

DBD1

I'm subscribed. I enjoy your builds, you make it look so easy. I learn something with each of your posts.
BTW- I'm enjoying (and learning from) your book as well.

Don

radfordc

My Feedback: (14)

I love Contenders! Only thing is that if you leave the wing flat it has a ton of adverse roll. You give full left rudder and the plane will roll to the right. It helps to raise the wingtips about 15-20 degrees.

tomclark

radfordc,
The nice thing about Contenders is rudder is only used for takeoff and knife edge flight. I don't remember the adverse roll you mention from mine, but it was a long time ago. I finished this one today, so will test fly it as soon as we have a nice day.

DBD1,
It is easy. All anyone has to do is look at the photos and see just how simple scratch building can be. Which is I guess why I like to post threads. My Gallery photos show there are many craft that can be built with these simple techniques.

By building the flat wing construction is super simple. Notice how the ribs set flat on the workbench. I forgot to take a photo of the spar doublers I used. It was just like a shear web between the two sets of spars, except they were made of 3/16 plywood.

Note nothing elaborate around the servos, just some of the 3/8 wide balsa used for cap strips for the ribs. The servos are mounted to 1/4x3/8 hardwood. Don't for get to leave a string in place so you can pull the extension wires to the exit holes.

The wingtips are 3/16 balsa for lightness. They have a small piece of 3/16 around the outside so it looks like the material is 3/8 thick like the ailerons.

tomclark

One of the coolest moments when building is when you pin all the pieces together so you can finally get an idea of what the thing is going to look like, and the size of it.

The second neatest thing is putting all the parts you built in a stack on the old baby scale. In case the photo is too small, all the balsa parts weigh just under 2.75 lbs. The only thing not finished is the nose - I just wasn't sure how to go about making it look like the plan. Being a cheapskate, I don't like just gluing on huge chunks of balsa and then start carving. I just kind of ad-libbed it, gluing on small pieces and then quitting once it started looking ok… That way a minimum of carving and balsa waste is required.

Note the simple way the wing dowel is mounted. It would be too close to the edge to put it in the center of the leading edge, so a small piece of 1/4" ply is epoxied in place, then the wing mounted, and the hole is drilled both through the plywood in the fuse, right through the plywood in the wing. The dowel goes right on through until another hole is drilled in the plywood doubler on the main spars. There is no way This 3/8" dowel is ever going to fail.

The wing bolts are drilled right through the wing into the plywood blocks that were epoxied into the plywood support at the back of the wing. After tapping the 1/4-20 holes, the holes are soaked with CA to harden the threads

skylark-flier

Book? BOOK? You've got a book and I don't know about it??????????????

Don's right - you have this habit of making it all look so easy. However, it's guys like you and Mike (and several others) that pushed me into this winters' 4 restorations - every one of which is a screaming success. I owe you guys a lot for that, all us dinosaurs do.

I've never had a Contender ... that may have to change. It looks like a great aircraft.

I love reading and taking notes on these build threads. I've learned so much - wish I was still 40 years old so I had time to built XXXXX more planes. Besides, this is all so much more fun than opening a box, charging a battery and buzzing around with a plane that looks exactly like everyone elses.

Press on my friend, press on!

tomclark

Once all the balsa dust has settled it's time to start another favorite part of building; covering. A couple of planes ago I discovered Chinacoat. At 1/3 the price of Moneycoat it is a cheapskates's dream come true. Even better is that is is a lot easier to cover with than the old stuff. Hard-to-do curves like wingtips? They become so easy that I still have a dozen rolls of the other stuff left over that it will be a challenge to use up.

Note in the photos that it is a good idea to use a little help to make sure everything stays square when gluing on the tail surfaces. I cover them first, keeping the covering material a bit away from the glue lines, then afterwards go back and cover the glue lines with small strips of material. This keeps everything sealed and eliminates places where fuel could seep in and weaken joints over time.

My covering jobs will never be as pretty as the ARFs, but they darn well will be easy to see in the air, and especially easy to be able to tell the top from the bottom. When I am flying the bottom is not on the bottom all that often.

tomclark

I hope these colors will be easy to see in the air. Since I had my cataracts done last year my airplanes don't disappear in the air nearly as often as they used to.

This plane was three weeks start to finish, and a good part of that was teaching myself a new computer radio. Dinosaurs don't like learning new things, especially when the instruction manual is so poorly written. After 35 years of being a Futaba loyalist, one of the new cheap radios has won me over. It's a Tactic 850 8 channel. You've seen the ads, and reading about it on the forums has helped to get me to try one. 8 channels and a 30 model memory did the trick. My only other 2.4 was a 7 channel Futaba, and the 10 model memory was full. I was thinking about getting another one, but the receivers are $70 each, and the Tactic dual antenna receivers are $25 for the 6 channel, and $45 for the 8 channel. Cheap, remember?

Instead of using the old nylon thingies for hooking up the control surfaces, 15 years ago I switched over to using 6-32 bolts and these little nylon gadgets for attaching the push rods. Super simple to install, just drill a .136 hole, soak the balsa with CA, put the washers and nut on, add another drop of CA around the finished installation, and your done.

Dino -like, I still pack the battery and receiver in foam, and wrap that lightly with masking tape. All of these little details are part of not liking to crash. Love building - hate crashing! Date your batteries and replace them after 8 years works for me. Also, using masking tape on all plugs, like where the servos plug into the extensions, where the battery plugs into the switch harness.

Love this photo up the rear end of the model. It shows the elevator and rudder servo installations. By the way, trying some of those china brand servos. 75 ounce thrust for $5.60 instead of $20+ for the Futaba models. Put one on the rudder and flap to test them out. Once again, researched them on the net before stepping out of the dinosaur costume long enough to give them a try. Hey, if I loose rudder or flap control at least I will still be able to land the plane under control. Once I gain confidence in them they will be hard not to buy.

On the Contender there is a huge central flap with its own servo. I have it set for about 35% of drag - coupled with a bit of up elevator, which will change with the test flight.

tomclark

Two things I didn't mention: The engine is a new ASP 1.08. Once again researched them on the forums. (Thanks for all the info guys!) I have two Magnums, a 91-2c and 91fs. Have about worn the 2c out since buying them when they were on sale in 2007. It has been an excellent engine. Just started using the 91fs when I built a 76" Tiger last fall. It runs great and carries the Tiger around in style. OS has just priced themselves out of my market, and this ASP 1.08 was under $90 with muffler. Good Gads! By the way, ASP engines are the same as Magnum engines. Same factory.

The landing gear is just bandsawed out of 1/8" thick T6061 aluminum. Do not try using a softer aluminum. Many arfs use softer aluminum and it has no spring, so you have to rebend it all the time. After bandsawing I hit the edges on a belt sander to clean them up, and file the burrs off. I screw to plywood that is firmly epoxied into place. The gear ain't coming off unless the wing comes off - and the wing ain't coming off unless I hit something really hard - and then I won't care.

Clean workbenches. Plane is done and ready for test flight. Of course the bench won't stay clear long. Already planning a 2 meter Kaos with a thin wing. That will be my $100 version of a $3500+ pattern plane. Maybe another build thread then? (Note: 2/17/15 Thread here.)

For many years I used to have the newbies over to my shop to help them get started in kit building, covering, radio installation, etc. I even gave talks at club meetings about scratch building and designing your own. For a long time magazines used to publishing building and designing articles, and I saved all that interested me, and put them in my notebook. Then I wrote a simple book about designing and scratch building to help my friends get started. Still have a few left, but it will not be reprinted when gone. It's on my web site, so just Google "The Sunday Flyer".

On my blog, you will find short articles and links to my building threads. Surf through it and enjoy.

I'll be back with a flight report soon.

Meanwhile, if you have any questions, ask away. Comments? Let's hear them. Build threads are for chatting, so let's chat.

DBD1

Tom, I like the color scheme. It should be very visible in the air. I will be interested to see how the Tactic radio gear performs for you over time. It sure is a lot less expensive than Futaba gear. Likewise with the Asp & Magnum engines, I have been leery of buying one, have read that they are hit or miss. Where do you obtain the clear canopies for your builds?

DBD1

Ditto on that statement!

Dave- I just got Tom's book "The Sunday Flyer". It is a no nonsense, not to technical, but very informative read and reference book. If you are at all interested I suggest snapping up a copy while it is still available. I think you would enjoy it, I'm glad I got mine. http://www.tomclarkbooks.com/The_Sunday_Flyer.html

radfordc

My Feedback: (14)

I would think that being cheap (like me) you would have discovered the Futaba compatible FrSky and Orange Rx's. They work just as good as the Futaba name brand ones and cost about $30 each. I've used them for several years now without a problem.

http://www.valuehobby.com/radio-syst...-receiver.html

http://www.hobbyking.com/hobbyking/s...arehouse_.html

tomclark

I was in a hobby shop long ago, somewhere, and they had a pile of the plastic canopies on a shelf. I bought 4 of them and still have one left. No idea where it was. (When we lived in Florida, after retiring in '97 we traveled in our motorhome 6 months a year.)

I recently did an online search for canopies, and mainly found small ones for arfs.

Oh, the hit-or-miss posts about the ASP engines I read were from around 2006 or before. Later posts are a lot better. Before many fliers were just replacing the carburetors.

Remember back in the days when hobby shops actually sold stuff for building? It sure was a long time ago. Nearest hobby shops to me now are 2 and 3 hours.

For my next project, the two meter Kaos, I will be carving a canopy similar to this one made long ago for a 60 size UFO. It will be about 24" long and carved from foam.

Larry882

Hey Tom,
Just enjoyed going threw your build thread. Plane looks great and I hope it flys good.
Thanks,
Larry Kopecky
Conyers, Georgia

Instructor

My Feedback: (16)

Hi DBD1,

Check out this link for plastic canopies. They have all sizes and shapes....

http://parkflyerplastics.com/cart/

Larry/Instructor

tomclark

Larry, Thanks for the info. They have lots of sizes.

For reference, the canopy on the Contender is 14.5".

Seems like everything is available on the web. It's just finding it is the hard part…

Tom

ETpilot

Tom, this thread brings back memories. The Contender was my first low wing plane that I built n flew. I've been looking at build threads and find your's very interesting. I am just getting back into RC and I like to build. I started with an Ugly Stik, also a favorite that I flew long ago. I found the plans on the forum, copied and had them blown up to 11x17 sheet. I built it from that. Not sure if I am a plans builder or a scratch builder. I haven't seen the terms well defined.

And yes, when you build you can make it any size and add any mods that you want. One of a kind airplane.

Anyway, the Contender looks good. Have fun flying it. Looking forward to other threads you post.

thailazer

Tom... Great looking project and it is exactly the kind of planes I love to build and fly. Surprising how little interest there is on scratch building threads these days, as that is really the foundation of RC Flying. Appreciate the photos you are posting.

tomclark

Hey ET,

To me, a plans builder is someone who copies the build exactly as it is on the plans, changing almost nothing. I read in the threads how many builders pay someone to cut a kit for them even. Wonder why? A scratch builder takes a small plan, and builds it what ever size he wants, bigger or smaller, ignoring the construction detail on the plans and builds it his own way. My definition anyway…

I wonder how many of you guys ever saw this book put out by RCM way back when? I bought it long ago, and built about a dozen airplanes using the small plans as a guide to draw my own plans in whatever size I wanted to build the plane. I think the book had around 500-600 plans from the magazine. I never did purchase a full size plan as I never wanted to build the size the original article was about. As you saw on my blog, (linked above) I like to blow things up.

radfordc

My Feedback: (14)

The Contender was also my first low wing sport plane. I got my first one in 1972 and built another one some years later. A big Contender should be a great flying bird!

Larry882

Hey Guys,
I like to blow things up too. This took over a year to build but flew great. It required 6 1/2 pounds of nose weight. I have a Auto Cad drawing if anybody is intrested.
Thanks,
Larry