Login Into Website

The calculator needs to know your username so it can save and load your calculator components (airplanes, motors, etc.). It gets your username from the website when it first starts running. Before running the calculator, you need to be registered on my website and you need to be logged in.

How do you know you are logged into the website? Look at the box right below the tutorials on the left side of the screen. If the title of the box is “Login”, then you are not logged in. If the title is “Welcome xxx”, then you are logged in and your username is xxx.

Note also that you need to enter your username, not your email address, to login.

If the title of the login box doesn’t say welcome, then you need to fix that before running the calculator.

Adobe Flash

My calculator consists of about 50,000 lines of ActionScript code. ActionScript is the version of Javascript used by Adobe Flash. Actually, I wrote the calculator using Adobe Flex, which is a programming environment that runs inside Flash. The current version of the calculator was compiled against Flash player version 11.1, which is also the latest version at the moment.

The good news is that my calculator runs anywhere that Flash runs. It is fully compatible with Microsoft Windows, Apple Mac OS X, and Linux. It is also fully compatible with both 32-bit and 64-bit versions of the Flash player. It works fine in every Internet web browser I have tested it in.

I’m completely dependent on a properly installed, running, and up to date Adobe Flash player on your PC. There is simply no way around this requirement. Flash blocking add-ons in your web browser will prevent my calculator from running.

The calculator tutorials and polls on my website also require Adobe Flash to run. But all they need is Flash version 9, which is a lot more commonplace. If you have Flash already installed on your computer, you probably have at least this version.

Note that Flash applications run from your PC, not my server. All my server does is send you the file to run. The applications run in a secure environment that deny them access to the rest of your PC. My calculator has no access whatsoever to the files on your hard disk, for example. But this also means that when the calculator optimizer runs, it is running on your PC. If your computer is on the slow end of the spectrum, it will take a little bit longer to optimize your power system.

Display Problems

These types of problems are less common today than they used to be, but sometimes the screen display of my calculator gets garbled. This is likely because of an out of date video card driver.

Doesn’t Run Right

By one estimate, about 50% of all websites have some sort of Flash application running on their webpages. What this means is that, if you have been web surfing for a little while before visiting my website, it is possible for the Flash runtime environment to have been corrupted somehow before you ran my calculator.

My calculator is one of the most complex Adobe Flash applications ever written. Adobe employees have used it as a showcase of what can be done in the Flash platform. The downside is that it is vulnerable to poorly written Flash applications that may have been running inside your web browser.

If you run my calculator and it somehow acts funny, this is probably what is going on. Usually exiting the calculator and rerunning it fixes these types of issues. In a worst case scenario, you may have to exit your web browser and run it again.

Useful Troubleshooting Links

Here are some very useful links for checking your Flash player installation, installing a new version, and troubleshooting it.

Adobe Flash Player Status Check

Install or Upgrade Flash Player

Flash Player Settings Manager

Adobe Flash Player in 3 Steps

Mozilla Firefox Flash Player Guide

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The next video is a real full-size airplane losing a wing. No, he doesn’t land it. He deploys a ballistic recovery parachute.

Finally, there is real footage of a model airplane losing a wing and landing safely. Yeah, great pilot.

Model airplanes have much higher thrust to weight ratios than real airplanes. If you keep the throttle up, you have a decent shot at landing it. In a full size airplane, the gas tanks are normally in the wings. Unless the pilot acts very quickly, the engine is going to be sucking air and just shut down.

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RCadvisor.com has just been recognized as a top aviation website. Yipee!

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Summary

The Outerzone website is a listing of free vintage and old-timer model airplane plans to download. At the time of this writing, the total count of plans stood at 2,428.

The Good

This website delivers, in spades. I typed in “mustang” into the search box, and I instantly got a list of 18 P-51 Mustang plans. The wingspans ranged from 15 inches (38 cm) to 64 inches (163 cm).

I got a little more adventurous and typed in “tailless”. The search results came back with five plans. Not bad. I checked out the Penumbra, which turned to be a very attractive glider. Nice.

With a little more digging I even found a gorgeous Sopwith Pup. With just a 12 inch wingspan and 25 grams flying weight, it’s intended for electric RC. The computer drawn CAD plans were released in 2011.

All of the plans are in Adobe Acrobat PDF format. The stated goal of the website is to only include plans that are of good enough quality to build a model. All of the ones I looked at easily met that goal.

Many of the plans are beautifully drawn. Most of the plans appear to come from old model airplane magazines or kits. A lot of loving care clearly went into them. I easily see myself printing some of these plans out and framing them to hang on my wall.

A very handy Tag Matrix interactively lets you narrow down your selection of plans by attribute. Another very handy page describes techniques for working with these plans such as for printing them out.

The Bad

The plans from magazines generally include the year but not the month. Having the month of publication would make tracking down the actual physical magazine issue easier.

Reading the small writing on some of the plans is very hard. Printing out the larger plans could be a challenge.

The website makes it clear that it runs on a budget hosting plan. Although it ran fine for me most of the time, they warn about frequent slow downs and even outages.

The Ugly

Don’t count on getting anything beyond the plans. Sometimes the building instructions are printed right on them. If the plans you are interested in building has them, consider yourself very lucky. Most of the time you are on your own.

In many cases a small picture of the completed model is shown on the website. I did not see any way of obtaining a larger version of these pictures. I never saw any construction photos.

Don’t go looking either for instructions on selecting and installing a modern power system. In fact, most of the models appear to be rubber band powered free flight. I found 686 plans for free flight rubber scale model airplanes.

For giggles, I searched for the word “foam”. Three models from around 1970 that pioneered the use of foam in model airplanes popped up. Three more than I was expecting…

Conclusion

There are many classic designs included in the collection. I found several plans for versions of the Playboy Senior, for example. I found 20 designs by Carl Goldberg. I found another 20 designs by Frank Zaic.

This website is an incredible resource. There is much to be learned about balsa construction techniques by studying these plans. Many of these smaller rubber band powered designs could be converted to micro RC gear and electric power. Doubling them in size would be an easy way to get a great looking (and flying!) park flyer.

http://www.outerzone.co.uk

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How big of an electric motor do you need to power a six foot (1.8m) Piper Cub model? Finding the answer is easy!

Six Foot Cub

Let’s say we decide to design and build a Piper Cub because the world cannot have enough Cubs. We want to make the wing span exactly six feet (1.8 m) because that is the size of our building table. How big of an electric motor do we need to power it? Whoa! Did your mind just go blank? You say you have no idea? It’s not as hard as it looks. Let us take it one simple step at a time until we get to the answer.

Full Size Cub

Look up the specifications for the Piper Cub. For the sake of argument, let’s say that it weighs 1,000 pounds (454 kg). The wing span is 35.25 feet (10.75 m) and the wing area is 178.5 feet squared (16.6 m^2).

The formula for the aspect ratio of a wing is (wing span * wing span) / (wing area). That doesn’t look too hard, does it? The units are not important as long as they are consistent. Plug in the numbers from the specifications and you should come up with the value 7. I know that it’s really a little bit less than that. Let’s just round it out. For the sake of this discussion, the aspect ratio of a Piper Cub is 7.

Given the wing span and aspect ratio, let’s compute the wing area of a Piper Cub as a check on the numbers. The wing area of a wing is (wing span * wing span) / (aspect ratio). Plugging in the numbers, you should get a value close to 178 feet squared (16.5 m^2). Again, we are still talking about the full-size Piper Cub.

Similarly, we can plug in the numbers we have to compute the wing area of our six foot Cub. I get 5.1 feet squared (0.47 m^2).

Airplane Type Constant

There’s a very simple formula that relates the weight, wing span, and wing area of an airplane. The value that you get is an indicator of how that airplane will handle in the air. The formula is (weight) / (wing span * wing area). The units are not important as long as they are consistent. In this example, we will use ounces as the unit of weight and feet (or feet^2) as the units of length and area.

Let us plug in the numbers for a full-size Piper Cub to find its airplane type constant. I get a value of about 2.5. So if we come up with a six foot model of the Piper Cub that has an airplane type constant of 2.5, it will behave in the air similarly to the full-size Cub.

Note that I said similarly, not exactly. The point of this article is to quickly come up with some numbers that can be used as the starting point of a detailed airplane design.

The airplane type constant formula may look very simple, but it is extremely handy. In fact, this is the formula from my first book that I use the most.

Flying Weight

Let us figure out what the flying weight of our model Cub needs to be to match the airplane type constant of the full size Cub. Rearranging the airplane type constant formula, we can compute the target weight of an airplane using (airplane type constant * wing span * wing area). For our model Cub, I get a value of about 4.8 pounds (2.2 kg). That is the target flying weight.

Motor Weight

We are in the home stretch! My electric model airplane power rule says that for a sport model the motor should be about 10% of the flying weight of the model airplane. I get a value of about 8 ounces (227 g). Since this is a Cub, we could get away with using less.

That’s the final answer: the electric motor weight of a six-foot Piper Cub model airplane is about half a pound.

That was not as hard as it looked at first, was it?

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Listen in to find out!

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Preparation

A lot of the same preparation advice as for a ground launch applies, so I won’t repeat it here.

Nothing used to bum me out more than a bad hand launcher. Yes, I know they mean well. But I don’t know what in the world makes some people believe that launching a model airplane is like throwing a baseball. Recovering from a launch like that is almost impossible.

Now I take matters into my own hands. They are not touching the airplane until I’m certain they know what they are doing. I don’t care how much RC experience they have. I don’t care how well they can fly. All I care about is how well they can hand-launch a model airplane. It’s a javelin throw, not a baseball throw. No arch to the hand movement whatsoever. Straight and level. Not up. Not down. Wings level. Wait until I throttle up. Just let it fly off your hand. I control where the airplane goes after you let go, not you. Show me how you are going to do it. Again. Okay. Now you can touch the airplane.

I have heard that sometimes the launcher runs before letting go of the airplane. Sounds plain stupid to me. I cannot imagine them having very good control of the airplane when they let go. A wild throw is never good. For a very challenging model, once I had the launcher lifted up by a crane. It sounds funny now, but it worked beautifully at the time. Getting the airplane up to the poor guy for a relaunch was a challenge, though.

The launcher is in a better position than you to detect problems with the airplane. Teach them that they have the power to abort the launch if they have any suspicion that anything is wrong. I would rather be safe than sorry. After a couple of false alarms, they learn what are the real signals to watch out for.

I remember one time a hand launcher felt that the motor was not giving full power. To me, everything looked good. It turned out that the battery had gone bad, and I had no idea. His alertness and confidence to abort the launch saved the model.

Where to Stand

I like to stand close in at about the four o’clock position on the same side as the model. Let me explain my reasoning.

I stand close to the launcher so that I can keep a close eye on the model. I look for anything that doesn’t look right, and I also listen for the motor being off somehow. Being close in helps a lot in communicating with the launcher, too.

I stand on the same side as the model. The last thing that I want to happen is to lose sight of the model right after it takes off. Ain’t gonna happen on my watch.

I need to stand somewhat behind the model, but I don’t want to risk the model veering off and going behind the launcher. Standing slightly behind him works well. Another benefit of standing there is that the launcher can communicate back to me without too much trouble.

Power Up

Maybe it’s just from my general paranoia about avoiding problems, but when I apply power to the model I do it in two stages. First, I do a low power “everything still green” power check. I listen to make sure the motor sounds good and nothing is vibrating excessively. Then, a second or two later, I go into take off power. Be sure and tell the launcher to expect this! In practice, this has never been an issue.

How much power for takeoff? One school of thought says that you should always apply full power. I don’t agree. Full power is more likely to bring out trim problems in the model. What I do is try and give it just enough power for straight and level cruising flight. If I miscalculate and it’s only enough power for a long glide, that’s fine too.

This is my reasoning. The last thing I want is a squirrely airplane when something is not right. I would much rather see the airplane in the air for a couple of seconds first, and then if everything looks good, I apply more power until it starts climbing out. I have done it this way many times, and it works.

As with a ground launch, don’t try to climb out too soon. Give the model a chance to pick up speed first.

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Preparation

These are the basics. Preflight the airplane. Make sure the battery is charged and the gas tank is full. Make sure your gas tank is full, too. A tired pilot is a sloppy pilot.

Look to see who’s already flying, where are they flying, and what are they doing. Where is the wind coming from? How steady is it? The goal is to takeoff into the wind from a nice, long, smooth, and level runway. Use 15 degrees of flaps, just don’t forget to take it off after you finish climbing.

Ideally you want to stand behind the model. If not possible, do your best. Also, try hard to avoid having the model fly behind an obstruction after it takes off. Whether it is your best buddy or a pole, you don’t need that kind of excitement.

Most clubs require the use of a spotter. Use one even if you don’t think you need one. Make sure they know what their job is. Too often they think their job is to keep the idle conversation going. It is not. Their job is to alert others about what your airplane is about to do, and to alert you about what the other airplanes are about to do. That’s it. If your spotter starts getting chatty, give him a job to do to keep him busy.

Ground Roll

Make sure the runway is clear. Nobody else about to take off or land. Announce your take off in a loud voice.

Apply power smoothly and steadily. Don’t stop moving the throttle up until you hit 100% power. Keep a close eye on the direction the airplane is headed. If it starts to veer off, smoothly apply a rudder correction. If it is a taildragger, chances are that it will first lift up the tail wheel and then take off all of its own. Tricycle gear airplanes are designed to require up elevator to take off. So when do you know it’s the right time to pull back on the stick?

With experience, you will know when is the right time to give up elevator. Otherwise, give it some up and see what happens. If it doesn’t take off, neutralize the elevator and wait for the speed to pick up some more. Then try again, being gentle with the stick and watching the model carefully for signs it is ready to take off. It takes a little bit of practice, but before long you will know instinctively what to do.

In The Air

Immediately after take off, watch out for the p-factor and be ready to apply right rudder to compensate. Give the airplane a chance to pick up speed before getting into a steep climb. This is key! Too many times folks give full up elevator right after taking off, when the airplane has barely enough airspeed to stay up. The result is then a nasty stall/spin accident.

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1. P-Factor

No, it is not when you really have to use the bathroom and it becomes a factor in your ability to control the airplane. The P stands for propeller. You know, that thing up front that bites when you get too close.

A propeller blade is like a spinning wing. Just like a regular wing, the amount of lift or thrust produced depends on its angle of attack. When you have full throttle and the nose of the airplane is tilted up, like during a takeoff, the angle of attack of a propeller blade depends on which side of the airplane it is on at the moment.

Propellers normally spin clockwise when viewed from the pilot’s seat. If the nose of the airplane is pitched up relative to the direction of motion, then the rising blade will have a lower angle of attack than the dropping blade on the right side. Again, this is when viewed from the pilot’s seat. The propeller pulls the airplane to the left, so apply right rudder to correct.

Bottom line? P-factor will be strongest right after lifting off from the ground and whenever you are in a steep climb. Of the four forces, this is the best known one because it is the most noticeable.

2. Spiral Slipstream

Since a propeller generates thrust by rotating, the accelerated air coming out the back of the propeller follows a spiral around the airplane fuselage. But the vertical stabilizer and rudder normally only extend vertically up, not down. This means that this spiraling air column will push on the vertical tail only from the left side. Once again, we have to use right rudder to compensate.

This effect will be most pronounced at high power settings.

3. Torque

This one is easy to understand. When the motor (or engine) puts a rotational force on the propeller, the rest of the airplane will be rotated in the opposite direction. With a normal tractor propeller, the airplane will tend to roll to the left. While on the ground, the left wheel might end up with more rotational drag and pull the airplane to the left, too. To correct it (you guessed it), apply right rudder.

You are more likely to notice this force when the throttle is advanced rapidly. Since an airplane normally weighs a lot more than the propeller, this force is not normally noticed. The roll stability (dihedral) of the airplane will do a decent job on its own to compensate.

4. Gyroscopic Precession

A spinning propeller acts like a gyroscope. The faster it spins and the heavier the propeller, the stronger the gyroscopic forces at play. If the airplane pitches down rapidly, the nose of the airplane will tend to be pushed to the left. This is a left yaw and requires right rudder to correct. Conversely, a rapid pitch up by the airplane will yield right yaw.

Summary

I ordered the forces roughly in descending order of importance. Learn what they are and how they might affect your airplane. These four forces also interact with each other in complex ways. If your model airplane all of a sudden starts acting funny, it could be one or more of the four dark horsemen.

You say that your model airplane doesn’t have a rudder? Or worse, that it has one but you never use it? In a pinch, using ailerons to correct these forces is an option but definitely suboptimal. If you have a rudder, hopefully you now have four more reasons to learn how to use it.

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