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Archive for August, 2018
Posted by PeterVRC | Aug 19, 2018 @ 11:24 PM | 7,378 Views
I have decided to start dabbling... Learning.... about springs and how to make them.
This is for OLEOS, so that you can alter them and tune them to suit any particular aircraft and its AUW.
Most of my aircraft have INCORRECT spring/suspension strengths and qualities, seeing you only get to use what any given Oleo comes with - and they rarely come with a strength/behaviour that is truly suited. This is because a strength required has to match the aircraft AUW - which varies per any owners own 'version', and of course across the multitude of aircraft types and constructions etc.

On my Mig-29 I discovered the oleos I used were somewhere from JUST strong enough, to "too soft". They are just strong enough to hold its AUW if it is standing statically with no external influences on it, but as soon as it MOVES they will be driven to bottom out. You would think that this can't be a good situation to have.... but in reality it IS quite good. maybe not perfect, but still a very good end result. And much better than too stiff!!
This is because it is actually JUST short of able to hold the AUW, and even though they fully compress they are still operating as springs - any time the aircraft tries to LIFT UPWARDS they resume operation. And that occurs as it 'bumps' its way across grass, bumps etc. So they ARE doing useful things.

This outcome showed me that oleos that 'easily' hold up an aircraft are not going to achieve this aspect of useful operation. They will pass too much '...Continue Reading
Posted by PeterVRC | Aug 06, 2018 @ 11:29 PM | 7,446 Views
The GASB2 50mm Fanjet is just a first test of 3D printing techniques, and what results they give. To show SHORTFALLS in 3D printing.
I already know that a Single Perimeter surface has its 'costs'.
This larger "70mm" Fanjet is aimed to test out TWO perimeters..... 2x 0.4mm = 0.8mm.
Theoretically this means 'double' the weight of single perimeter.... but at least this design is almost totally 'empty' internally. eg no complex design/layout of ribs etc.

I quickly did a scaled up version of the 50mm.....
70mm / 50mm = 1.4 : 1
But no.....
70mm 6S = 1.6Kg thrust (in-plane), versus 50mm at 450g thrust in-plane..... That is 3.5 : 1.......
But no.... you won't make a plane 3.5x larger!

Next... the Funjet this is all based on has a 830mm wingspan for its 70mm Fanjet version.....
Hmmmm.... I want more lift.... so I settled on 1.8x in scale. A 1080mm wingspan.

I don't know what that will mean in the final flying result, but I am predicting the greater size and mass will make a more penetrating and 'linear' flying aircraft. It is not aimed at speed, just to fly well and be resilient!
Posted by PeterVRC | Aug 06, 2018 @ 05:47 PM | 7,437 Views
It was TIME to 3D print an RC Model aircraft......

I had been using 3D printers for many years and had seen bits and pieces (snippets) of how the world of 3D printing Aircraft was going. Nothing looked too great or promising in terms of producing a DECENT RC Model that would have everything doe well, and LAST. They were being designed and made 'too marginal', in their aims to save as much weight as possible. Let alone the 'entire modeling world' being so scared of WEIGHT and the ROBUSTNESS required to produce a truly "Fit for purpose" aircraft. The vast majority are 'marginal' and the weight phobia abounding everywhere means they fly like 'feathers' or 'bits of paper int he wind', not truly 'linear with mass and inertias as per full scale aircraft have and do.
So the WEIGHT of a 3D Printed aircraft was not worrying me, it was the actual construction details that would be needed to form a "Fit for purpose" aircraft, and THEN remain within a weight range restriction - even when that is WAY heavier than everyone else is doing in 3D printed aircraft.
In foam models, they are all way too light as they come.... well... in recent years the manufacturers ARE FINALLY putting more 'good stuff' into them, and not worrying about weight as much. Yet they are still not at a point of truly Fit For Purpose and robust etc. But you can buy a foam model (Kit or PNF) and ADD all that you need to make it fully Fit For Purpose (reliable, strong, lasting!), and still not end...Continue Reading