RC Aerobatics
Eric Henderson, 303 Shady Ln., Marlton NJ 08053; E-mail: [email protected]
THIS MONTH we will return to aerobatic challenges for you to try. Some months the column is dedicated to a particular theme and there is not enough room to include maneuver challenges. They are not very time-sensitive, so I add them when there is room.
This month you will get the chance to build your own series of maneuvers.
Before I get into choices, there is a letter from Oscar Suarez ([email protected]) that I want to show you. It discusses using a gasoline-powered engine for a Pattern airplane. (Petrol for the non-US readers.)
Oscar writes:
"This might be of interest to Pattern fliers. Since it's building season for you guys, some of you might want to consider the RCS 140 on your Pattern airplanes. The limits should be a standard 120/140-size airplane (no widebodies please!) and not over 10 pounds.
"I took out my YS 140 engine on an MK mount from my Prophecy and dropped in the RCS. It took some minor modification. The tank was converted to a 14-ounce fuel tank for gasoline. I dropped in an Ni-Cd battery for ignition and the module behind the firewall, well away from any receiver/servo component.
"I did have to make my own header to fit, and a Hatori pipe for O.S. 1.40 RX two-stroke. The addition of an APC 15 x 8 prop and voilà!—a gas-powered Pattern airplane capable of very good vertical. The tachometer read 8,900+ rpm! (Sea level, temperature between 80 and 90 degrees, high humidity.)
"The question that is always raised: 'Is it competitive?' You bet; I won Advanced last October during the Luzon Nationals. It is quiet and just needed a little adjustment for throttle management compared to the YS.
"Other advantages: cheap fuel—so cheap that now I'm starting to practice some P01 maneuvers without costing me an arm or a leg.
"It is a good practice airplane if you want! I just finished making a power-pipe and will test it next week. For those who want to go into gas, this is a good first gas-er.
"Negative side: It is an eyesore to look at with the ignition-wire hanging out and the big plug! But once the airplane flies, you wouldn't even notice it. By the way, you do have to make a big hole on the firewall for the ignition cap to go through.
"This engine may not be as exotic as EFI or DZ, but hey—it works! (I am not sponsored.) I still love my YS; it's going into my Typhoon 2000!"
Putting a gas-powered engine in a Pattern model is not a new idea, but the availability of viable gas engines is new.
The silencers that are available now are also a key issue. It is no good having power if you have a loud airplane.
It looks like Oscar has taken what is currently available and has created an airplane/engine combination that will work very well at a particularly low cost.
Even at the $2 a US gallon of fuel, it is 500–600% cheaper to run gasoline two-stroke mix than methanol/nitromethane fuel. Gas engines also tend to be more durable regarding bearings rusting and general engine-parts wear.
If any of you have items of this nature, please send them to me so I can share your ideas and inventions with the rest of the readership.
Combinations of Rolls and Loops
These are maneuvers you usually perform as complete in their own right. This month the challenge is for you to try as many combination options as you would like using only loops and rolls.
You already know how to do these maneuvers as separate components—especially if you have kept the back issues of Model Aviation.
The more variations you try, the more prepared you are for maneuvers that are present in Precision Aerobatics schedules.
You can begin the exercise with partial loops and rolls. Combinations can start with maneuvers you recognize.
A Split "S" is a half roll immediately followed by a half inside loop. An Immelmann is a half loop immediately followed by a half roll.
You can spice up both maneuvers by performing full rolls to enter or exit the maneuver. Then you can do two of them back-to-back. An Immelmann followed by a Split "S" is an elongated loop with two flat sections on the top and bottom.
All of the above can be entered the right way up or inverted, to add another degree of difficulty. You could design a flight pattern that has consecutive variations that you fly in the same piece of sky.
The Cuban Eight, which is defined by the fact that it is made from two loops that intersect with 45° lines, is another combination where you can vary the formula a great deal.
You can do half rolls on the 45° intersects. Full rolls on the intersecting 45° lines make it very exciting. You can enter from the bottom or the top. There is even an option where you can do this vertically. Get lots of height before you try it the first time.
Triangle Loops can have many options. There are three legs that make a triangular loop. The 45° up and down lines allow you to perform half and full rolls. The horizontal lines look great if you perform a full medium-paced roll.
You can do triangular loops consecutively and vary the roll choices, so that no two loops use the same combinations. There are roughly 10 permutations you could write down.
This is where you enlist that long-suffering friend to stand behind you and feed them out. It is hard to remember all the ideas you will have; writing them down is your best option, and it gets you used to hearing commands and inputs then putting them into your airplane through your transmitter.
For the more adventurous of you, there are the complete loops with rolls in the turn—quarter, half, and full rolls. Square Loops allow you to select the rolls in a similar way to the Triangle Loop. The combination options are nearly the same.
You could burn a full tank of fuel flying Square Loops alone. If you have taught yourself the necessary wind-correction techniques outlined in previous maneuver descriptions, you can keep these Square Loops in stage center for all to see.
You will find a much bigger challenge in the Round Loop. Try executing a half roll at the top of a loop. Gravity will help you keep the curve of the loop going.
The same will happen if you try a full roll, but it will not be long before you will see the need to add a little rudder and elevator to get the airplane to roll in a curved line.
The next thing to try is a half roll on the bottom of a loop. It's easy to do this with some height until you get good at it. You apply rudder as you begin the half roll so that you pick up the nose of the airplane just so you are level in the knife-edge position.
In a knife-edge loop you would, for example, with a left half-roll, add a lot of right rudder as the airplane is rolled. You would still have some up-elevator as the roll begins.
By the time you reach the knife-edge position, the elevator should be neutral; the rudder should be increased until the airplane is a quarter of the way around to inverted. At this point in time, the down-elevator should be coming in to continue the radius of the loop.
Okay, I accept that you may be a bit out of phase by now. Here is another way to try this.
Do the half roll with elevator inputs only. When you get comfortable with that, do the half roll with rudder corrections only. When you can do them both, you should be able to merge the skills.
After much practice, bring the airplane down to a height where the rest of us can see it.
If you come up with a series of maneuvers—aka a schedule—from all of the above, please send it to me so I can try to publish it.
Next month I’ll tackle the formidable Rolling Loop, where the model performs one complete slow roll while executing a complete loop! This is possibly the ultimate maneuver. It is in the 2002 Federation Aeronautique Internationale Finals schedule and is a total blast just to try—let alone complete.
Have fun! MJA
Transcribed from original scans by AI. Minor OCR errors may remain.
