VISTA v2 - a slippery pitcheron

[Piotrsko]

Well for starters, it is a control surface airfoil like that used on 737 tail feathers. That's probably a plus but maybe meh as a wing. The Google I did says it's quirky. However I'm still betting it stalls before the root airfoil even though at 10% it's thicker than the 7003 at 8.5% and has less camber.

Anybody using that combo, and how successful is it?

Official notice: I 've been wrong before. Lots.
My suggestion: swap them and use it at the root.

 

[Elvis]

Nice.. I am good friends with Mike.

I don't know about the airfoils you chose, but tip stalling is not necessarily a bad thing.

Stephanie combet has mixed and matched attributes from a couple great aerobatics glider airfoils and came up with the SC-17. I am very fond of the performance from this particular airfoil.

 

[bracesport]

@Elvis - is this the SC17 you are referring to?

 

[Elvis]

Yeah buddy that's the ticket!

I have found after a while that totally symmetrical airfoils exhibit a kind of hunting effect at a neutral angle of attack. Just a little less curvature on the bottom side makes all the difference without a noticeable sacrifice in inverted capability. The plane will fly itself easier.

The SC-17 falls under the "nearly symmetrical" category, which is a real sweet spot in my mind!

 

[Piotrsko]

That sg17 isn't that bad looking. Bit of an noticeable stall, but @bracesport designs have more than enough horiz stab to mellow that out. Looks like CG is around 35%. Got my vote for a multi purpose intermediate wing.

Give @Elvis a cigar, won this round. And yes tip stalls can be fun, 2 mistakes high, but hard on wings less than that landing.

 

[bracesport]

hi guys, here is a bit of progress towards the final design - it seems to be a hot topic on the foil sections so I will avoid that for now - the wing is 1.3m with a fuse of 0.93m - the V is 100 deg - the wing and tail have a small incidence to accentuate the droop nose while flying - kind of 'stealth' is the plan!

 

[Wildthing]

hi guys, here is a bit of progress towards the final design - it seems to be a hot topic on the foil sections so I will avoid that for now - the wing is 1.3m with a fuse of 0.93m - the V is 100 deg - the wing and tail have a small incidence to accentuate the droop nose while flying - kind of 'stealth' is the plan!

View attachment 154721 View attachment 154722 View attachment 154723 View attachment 154724

That looks really nice, at only 1.3m I think you should do a fully 3D printed one.

 

[FoamyDM]

Sexy Bird @bracesport *nods*

 

[bracesport]

I have scrapped my Hybrid fuse after the last landing, so yes I am thinking I can make this new fuse option!

 

[bracesport]

Some more progress on the Pitcheron design! At the moment I am printing some demo parts for the rotor mechanism.

 

[bracesport]

The rotor mechanism can take three full-size servos or a combination of smaller servos - three servos give us Pitcheon movement and elevators so you can run it as a pitcheron or a wingeron and in either case, you can trim each surface given the three servos - but will the built-up rotor mechanism fit in through the canopy hatch?

 

[bracesport]

I have started a new set of 3D prints for the Pitcheron fuse which I will try and pull a CF braided sleeve over to make a robust sample!

Five main sections plus canopy and tail - I will size the tail again after I have the CF braided sleeve epoxied over the printed sections - the sections have small notches to align them correctly!

my plan is to press in the joggled edge for the canopy using a 3D printed female mould - I will wrap the epoxied CF braided sleeve with cling wrap to get the surface as smooth as I can (I have done this once before on my Ridge Rat fuse).

 

[bracesport]

First prints are done - the canopy part is a tool I will attempt to use to form the 'joggled rim' in the fuse to seat the actual canopy part - the two smallest tail sections are glueing and the second batch of parts are on the printer - so far so good!

 

[bracesport]

This is the braided CF material - it is 50mm wide when flat - it should expand over the thickest section of the fuse and contract over the smallest section of the tail when stretched - we shall see!

 

[Wildthing]

This is the braided CF material - it is 50mm wide when flat - it should expand over the thickest section of the fuse and contract over the smallest section of the tail when stretched - we shall see!

View attachment 159387

I watched a build video on the Extreme balsa plane and any open wood to protect from fuel he used 30 minute epoxy and thinned it out with alcohol to a point of being like water , Might be worth a couple test pieces trying different viscosities of epoxy when you do coat the cf cloth.

 

[bracesport]

Yes, I wondered about that - The viscosity of the 'Wests105' that I use is not too bad but I will do some experiments given the epoxy needs to be applied from the outside of the braided tube and permeate in - I use cling film to attempt a smooth outer surface, and this time I bought some 50mm and 100mm wide pre-cut rolls of packaging cling film!

 

[bracesport]

a bit more progress!

 

[Wildthing]

a bit more progress!

View attachment 159432

That looks really pretty

 

[bracesport]

I guess I will 3D print the tail feathers too once I get the fuse made up with a skin of CF - the tail should be reasonably safe and out of harm's way as a 3D printed section!

 

[bracesport]

Here is the CAD for the 3D printed tail cap and feathers - I opted for a 20mm plug for the feathers onto the tail cap and put an allowance for a 4mm pin between the parts into a rib/spar to strengthen the feathers.