So I have finally found some time to finish the front wing + stab. They were made in the 3D printed mould and unfortunately I learned a painful lesson not to use a big piece of sponge to fill the mould between the halves... When I closed the mould and squeezed the sponge between the layers of carbon, the sponge released a huge amount of air bubbles which all travelled to the surface of my wing (which I was obviously unaware of)... This resulted in a terrible surface finish and it took me few more days to fix it. I learned my lesson and for the stab I used a thickened epoxy as a filler and it worked fine, also I put a lot more attention to finishing the mould so the surface finish from the pictures is out of the mould with zero sanding. By the way the stab took less than 48 hours from design to finishPrfctChaos wrote: ↑Thu Jan 14, 2021 4:42 amNice, a fast freeride wing is awesome fun, good choice.salvatoreone wrote: ↑Thu Jan 14, 2021 1:53 amHi PrfctChaos,PrfctChaos wrote: ↑Tue Dec 01, 2020 4:10 amHi Robke,
I think the below freeride wing looks pretty good. 750 mm wingspan, 750 cm^2 area (It is just a touch larger than the theoretical minimum zone, but going down to 600-675 cm^2 only has a very small advantage). Recommended profile is the S2055. Make it in Polished aluminium would look awesome (would be a bit worried about damaging the thin trailing edge, but would definitely look awesome).
I'm really itching to make another wing and I've been searching through existing calculations for some inspiration as to what I actually want and that one above looks promising. All the parameters are essentially valid for my case but I was wondering what would change if we make the wingspan smaller (you mentioned 600-675 cm2 has some advantage)? I think smaller aspect ratio wing could be a bit easier to make, store and transport, also I'm not sure if I'm after a hardcore racing wing yet
Also in another reply, you mentioned calculations for a stab. Are you able to calculate the optimal stab parameters for the above wing?
So for 750 mm wingspan and 750 cm^2 area, the results look like this. s2055 profile wins best general profile (Drag of around 2.5 Kg near middle of the range). And rg14a147 doing a bit better in the top half of the speed range (Best High speed biased selection).
For a smaller wingspan of 700 mm, the optimum shows up at a area of 700 cm^2 for this speed range. s2055 profile wins best general profile (Drag of around 2.6 Kg near middle of the range).
I'm sure both of these will have plenty good mid and top speeds. Can't go wrong with either.
Stab optimisation and matching for a specific front wing......... Hmmm..... It is possible, but the main problem is that there are too many extra measurements and info needed. For example, you would need to calculated / estimate the total drag being created by the front wing, mast, fuse and stab itself with the fuse length and front wing centre of lift over the speed range. Just to calculate how much unbalanced moment is left that the rider needs to take of. To optimise, one would then need to minimise the drag and unbalance moment for all the different possible stab profiles as well as a range of adjustment angles for the stab as well as front wings. I'm putting it in the too hard basket for now.
However, I can tell you that my current favourite stab is a fast little stab, that has a wingspan of 390 mm, Max chord of 50 mm and uses a NACA0008 profile. I find it to be really low drag and fun compared to many commercial stabs. Well balanced at a downward angle of 2.5 degrees on my fast surf wing. For your smaller wing you might want to start at about 2 degrees if I had to guess.
It's all looking a bit rough, I'll finish it nicely if it proves to be working fine
Two questions to you guys:
- How do you finish your moulds to get a nice surface finish?
- My wings are always a little bit "elastic", are you achieving 100% rigidity when you make wings?