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RC Aerobatics: Take off with a Snap!

RC Aerobatics: Take off with a Snap!

A takeoff with a 1 1/2 positive snap roll will get everyone’s attention on your flight right from the start! Before attempting this move, you should be proficient with performing positive snap rolls in general. When you execute this move, you must be in complete control and exit the maneuver at a safe altitude. Do not drop altitude throughout the snap roll as this can be fatal when you’re only feet from the ground!

Depending on the power to weight ratio of your aircraft, your throttle percentage may differ slightly. On most of my models, I prefer to apply almost maximum power throughout the takeoff roll and then decrease power slightly once the airplane breaks ground. Then I pitch the airplane up slightly by pulling back on the elevator control stick and apply the same direction rudder and aileron. I’ll release elevator to unload the airplane and ensure that it does not drop any altitude through the rotation. Then, once inverted and after 1 ½ snaps have been performed, I’ll release aileron and rudder input and apply a touch of down-elevator to sustain level inverted flight. While this may sound simple, there are a lot of different elements that need to be perfected.

FOUR STEPS TO SUCCESS
Let’s divide this stunt into four steps. In this example, we will take off from left to right. Always take off into the wind. If a strong crosswind exists, take off in a direction that is favorable.

Step 1. While on low rates, add about 80-percent throttle and apply rudder input as needed to keep the airplane travelling straight down the runway. With tail-drag-gers, you’ll need to hold some up-elevator and slowly release elevator input as the airplane is nearing the liftoff speed. Then, pull back ever so slightly on the elevator control stick until the airplane is in the air.

RC Aerobatics - Snap roll

Step 2. Once you are about 15 feet in altitude, flip to your mid rate and come back slightly on power if the airplane’s speed is too fast. Pull back slightly on elevator input and apply the same direction aileron and rudder to initiate the snap roll. In this case, we will perform the snap roll to the left, so we will need left aileron and left rudder. Sometimes, people are confused by the control inputs needed in performing snap rolls. When performing a positive snap roll, up-elevator is needed along with the same direction of aileron and rudder input. When performing a negative snap roll, down-elevator is needed in addition to opposite direction rudder and aileron. It is critical to time this portion of the maneuver so that the airplane will precisely execute 1½ rotations and exit inverted.

Step 3. Throughout the 1½ rotation, apply throttle (if needed) to keep the airspeed up. Once the airplane nears the 1½ rotation point, you’ll need to neutralize aileron and rudder so that the airplane stops the rotation precisely where desired. This step may take some time to perfect, so altitude and familiarity is key. After all, this maneuver should only be done on takeoff if you are confident in your ability to execute snap rolls on demand in a precise fashion.

Step 4. Since 1½ positive snap rolls have just been performed, you will now only have to apply down-elevator, as needed, to sustain your altitude. Once you are familiar with how to perform this maneuver, you can pull the throttle back to drop airspeed slightly and descend in altitude so that you are just inches off the ground while inverted!

I have just described the perfect scenario where little to no wind is present. If a severe crosswind exists, I recommend that you perform the snap roll into the wind. For example, if we are taking off from left to right and there is a strong wind blowing in, I would snap to the left so that the airplane snaps away from you. Heavy winds may cause the airplane to drift throughout stalled maneuvers like the snap.

Now you have the keys to fly the 1½ positive snap on takeoff with utmost pizzazz. I must admit, this maneuver is very exciting to both watch and perform, but it is demanding on your flight skills. Do not attempt this maneuver until you are fully capable of precisely executing snap rolls without any loss in altitude. Until next time, safe flying and always remember to have fun!

BY JOHN GLEZELLIS; ILLUSTRATION BY FX MODELS

Updated: April 10, 2015 — 11:44 AM
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4 Comments

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  1. My are the diagrams in these how-to articles always so small with text that is impossible to read?

  2. switching from low to mid to high rates on takeoff? I don’t think so, that’s a recipe for disaster. Learn to fly your model, then execute this stunt on high rates.

  3. Who writes this stuff?! They make it sound so easy. As if the problem to performing this maneuver is not knowing which control movements to make with the sticks?! If you are at the level in your flying where anything in this article is “new” to you then you are ready to go straight out and crash your plane!!! Oh yeah, on take off!!! LOL! This is a total recipe for disaster. Changing rates, flipping switches while you are about to perform a snap roll on takeoff so that you come out inches above the ground?! Oh, is that all? LOL! Pure comedy… I can guarantee one thing for sure after taking the advice from this article, this will be a VERY exciting maneuver for EVERYONE at the field. The guys are usually always ready to help you pick up the pieces…

  4. I agree with John’s comment. A double-snap on take off was kind of my signature move for years when I lived in the Midwest. And while this is great information in the article, I have to say you’d better be able to do snap-rolls “automatic”. If you have to think about all of this on take off, bring a trash bag with you to the flight box!

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