Huntsman

I'll use this page to document progress on the Huntsman F3F glider.


2 November 2014.

I cartwheeled my F3B Skorpion in an F3F meet not long before my hiatus from gliding (Addiction to Golf) and did some pretty significant damage to the wing roots on both wings.
I have now decided to use the fuz of the Skorpion to help me to prototype my F3F Huntsman wings!

The eventual fuselage for the Huntsman will be very different from the Skorpion, but I'll concentrate on that once I have some quick and effective wings for it.

This evening I ordered some glass and carbon to enable me to fabricate the wing from foam and then vacuum bag it.

I want to have a nice shape to the wing so I will be cutting the foam in sections. This will also allow me to be a bit creative with the aerofoil sections.

I'd like to build the servo's into the glider with RDS, but I'll think about that some more yet.

More updates to come in the not too distant future!

18 November 2014

I've started repairing the Skorpion wings and have repaired the fuz so I won't be using the Skorp's fuselage for the Huntsman wings.

So I've started a basic idea for the Huntsman Fuselage and glued 3 golf club shafts together as the basis for the fuselage aft of the wing leading edge. It's a bit heavy but is incredibly stiff so I think I'll get some tapered carbon tube for the next effort if this proves successful.

19 Feb 2015

I've gone through a few iterations of the Huntsman F3F in my head and also in attempts on paper and at the moment I am leaning towards building both 'x' and 'v' tail versions. With the advancements in manufacturing materials, equipment and processes made recently I believe it is possible to make the surfaces 'all-moving' without the perceived weight penalties so I'm going to do that.
It'll be interesting to see if it is possible, then it will be interesting to see if there is a benefit both in the air and in the transportation/rigging up of the model. Personally I'd love to not have to worry about tape for the tailplane and am looking forward to using magnets.
Some servos are extremely light and quite strong, so it might also be possible to have the tailplane servos mounted in the tail with more direct control rods without having the disadvantage of increased overall weight due to the balancing weight required to overcome these. Access hatches could contribute to some structural deficiencies or issues so that'll need testing or 'building-in' in the manufacturing process?
The wing planform idea had changed from a straight, constant chord centre section with tapered elliptical tips to a constant elliptical shape with a thicker chord giving the same wing area and a skinnier looking wing. Most F3F gliders seem to have an aerodynamic sweep (I don't know if that's a real term, but I'm using it to describe the centre of pressure in a line along the span) heading backwards to enable them to have control surfaces perpendicular to the fuselage in a straight line. My design at the moment has the control surfaces angled forward and the aerodynamic sweep perpendicular to the fuselage (even slightly forward). I have always preferred the look of a straight leading edge and am aiming that way, although not totally straight as it's elliptical.
I have been building the fences for the hot wire to travel on lately for cutting the foam cores for the prototype. I am aiming to cut each 1500mm core in one piece, although this could be a 'bit' ambitious due to the wire flexing, bending and stretching. I think it is still worth trying and having the planform accurately cut out before cutting the cores should help, but we'll see!
I'd love to have the cash to be able to bypass this stage and go straight to getting a mould cut in Stainless, but them's the breaks I guess.
A foam core wing should be plenty strong enough and also plenty light enough, especially with the current trend of flying as heavy as the conditions can take. I'll be building in the servos after vac-bagging the upper surface while fitting the spar, joiner box and ballast provision, then vac-bagging the lower surface. Good, thick spar caps from carbon tows with carbon laminated balsa vertical in the foam should keep the flexing to a minimum. Similar sub spar idea without the caps.
The joiner is going to be 12x12 carbon square tube laminated together either 3 or 4 wide depending on where the centre of balance is likely to be. The joiner should be able to hold quite a substantial amount of ballast!
I'm going to splash out on some 3 layer Carboline (+45,-45,0 and -45,+45,0) from Vladimir's models so that I don't have to add too much material and the core will act as a sandwhich material. 
I'm really struggling getting anything done at the moment because any time I have off work is spent looking after the kids or trying to be considerate to the neighbours late at night by not being too noisy. I really need a small industrial unit with an office to put the kids in!
I'm a bit nervous about putting my ideas down in writing, in public. But as someone who is not trained in aerodynamics, mechanical engineering........... anything really, it's fun to make some progress on my daydreams and work towards turning them into a reality. A massive thanks to Thierry Platon for letting me use his aerofoils! That's definitely one part I didn't want to guess!

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