My Posts: All Forum Topic
A good 3D heli is one that is not overly heavy, rigid frames so control inputs are precise and don't suffer from flexing or slop, and it offers predictable response to given inputs. However most modern helis are pretty good provided they are setup well. Obviously having a bigger disc to mass ratio is better so as to achieve more axial rolls etc, but now with the advent of helis like the trex 600, this class is now just about as light as it can get 3.2Kg is very hard to better. Same can be said for 90 size where the 4.7Kg is about as good as it gets. Along with weight reductions, manufacturers are also taking the obvious step of keeping the battery mounting high to keep the CG up for better axial rolls etc.
Much of heli design is a materials issue where one should use the correct materials for the job in hand; CF where strength and stiffness is required, plastic where some flexability is useful in absorbing vibration and aluminium alloy for making inflexaible, light and strong components. These are becoming well understood.
New developments in flybarless systems is having a substantial impact on the 3D heli scene, with it's advantages of simplified mechanics (& consequent weight saving) and removal of the power required to drive the flybar system which can be upto 25%.
Another area that manufacturers are beginning to recognise are the design of tail grips which incorporate chinese weights. These dramatically reduce the tail pushrod forces and hence workload experienced by the tail servo, so it can perform with greater ease.
Most manufactureres now recognise the advantages of eCCPM and so have concentrated in developing helis offering good geometry, mechanical simplicity and the frame design to appropriately maintain accurate mechanical linkage from the servo to the swash. Thankfully, servo manufacturers are responding well with the new requirements with the introduction of servos such as the 8717s. Equally, due to the power requirements of these, this is being reflected in the available batteries, regulators, connectors and heavy duty cables.
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