• Jon

New Project - Grumman X-29

Updated: May 20

I have recently shared a few new or ongoing projects and I thought I would share another. I started this one back in December. It took a back seat for the Porter and Skymaster whilst I was waiting to get hold of an appropriately sized EDF.



The EDF finally arrived yesterday, after being stung by customs charges again, which by the time you have paid the charge and the handling charge was outrageously expensive. I must remember not to buy anything from HobbyKing if it can't come from the European warehouse as it simply isn't worth it.


It is here now I finally had a chance to measure it up and start designing the mounting hatch for the EDF.


The Grumman X-29 first flew in 1984, it was designed to test forward swept wings, canard control surfaces and other novel technologies such as Vortex Flow Control. It utilised a full fly by wire control architecture in order to tame the instability caused by the 3 control surface design. The 3 surfaces, canards, flaperons and a tail strake, all combined to give the aircraft impressive high angle of attack manoeuvrability.


One of the original design challenges was to over come the aeroelastic instability. This is when the forward swept wing is twisted by aerodynamic loads, instead of reducing the AoA and therefore lift like a conventional swept wing, returning the wing to normal, it increases the AoA and lift, twisting the wing more and repeating the pattern, divergent instability. Everything you could ever want to know about the X-29 can be found here.


From a modelling perspective I have decided to dismiss the movable tail strakes as it adds complexity and weight to the design. I plan on using one servo for the canard to control pitch and one each for the flaperons on the wings. I am going top use a 64mm EDF. I think I am also going to enlist a test pilot more familiar with flying this kind or aircraft when I finally get to the flight testing phase.


There is still a way to go on this design, I still need to find ways to mount the servos, cut out a rudder, shell the cockpit for the electronics and think about the internal structure through the centre of the fuselage to make sure it is strong but also lightweight.


I would love to hear you thoughts!


Jon



 

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