UPDATE: Watch the new video: • Young Engineers: How t... Buy the Rubber Band Helicopter project kit here: amzn.to/2ROfNWs Buy propellers: amzn.to/2BuDiYN Be sure to check out www.madeforste...
The counteracting force is the paper cutout. Of course it doesn't completely prevent the heli from spinning, but without it it wouldn't work. Check out the link for a more detailed explanation
you could put fins on the bottom that deflect the prop wash, and set them so that they negate the torque from the propellor, so that more of the rubber band's energy goes to turning the prop instead of the body.
That may be so but the fins will change a component of the downward vector to a side vector which could be looked upon as the body having a greater drag , so while the rubber band energy goes to turn the propeller, there will be more drag on the body. It would have been better to use two contra rotating propellers, where the reaction of one will be taken by the other and the body of the helicopter will not be subjected to any reaction by the rubber band.
Carmel Pule' true, he could do that. He could have each of the props be driven by its own rubber band. Or he could have one rubber band spinning both props through a gearbox (they've done that before, I had a rubber-powered plane that had two props that shared the same rubber band. They were connected through a gearbox. It was a model of the Wright Flyer). Or he could design a new body that's similar to the Vectron series of RC aircraft (the ones where you squeeze a trigger on the remote to make them go up and down) and have a circular body that has special, downwards-angled aerodynamic support struts. The torque of the prop would spin the body the opposite direction, but the body would take advantage of that by acting as a second prop and generating more lift.
I got them from: SIG Mfg. Co., Inc. 1-800-247-5008 Description: SIG 5-1/2 IN PROP&NOSE PC (6) $5.45 You need the prop with the nose piece to attach it to the Popsicle stick.
