Show us what you are working on..

[j ferguson]

Mostly done. It now weighs 2.2 lbs and CG is still an inch behhind the fore-wing trailing edge.

I still have to print another hatch cover (for snugger fit), calibrate the S6R, and make sure the prop doesn't drag. It is a 10X6 but I should probably be safe and go to a 9X7. I made a little stopper so the blades won't eat the rudders nor spin up inside out. I'vd located a not-so-nearby r/c flying field which doesn't have a pond at the end of the runway.

The elevon hinges are those nice small Du-Bro nylon ones with the brass pins. It was a bit of a challenge to keep them aligned while I glued them, but elevon motion is pretty smooth so I must not have screwd it up.

I have a question. The elevons on the real(!!) SB300 are conected to the wings by continuous tape or something similar, hence no gap in their wings. Would you close this gap?

I've thought of gluing thin vinyl strips one for each wing underneath the aft edge to close this gap. What do you think?

Hopefully there will be a calm day next week and I can go out to see if it will fly.
John

 

[rcsoar4fun]

Circling back to my Top Model Discus 2C, I was annoyed my Hitec mounts and other "custom mounts" didn't fit.

I am fairly happy with the fit on these.

 

[Wayne]

The new exercise program at Aloft - Go drag the parachute down the street.

(Seriously difficult workout, most volunteers are gasping for air in less than a minute.)

This is an old ultralight emergency chute.

Trying to think of a use for it at Sunset.

 

[rcsoar4fun]

Time for a 1/4 scale Cirrus.

 

[RafaelAvila]

Who never thought it should come in a hard case? So I make my own for this amazing receiver with this great firmware

 

[jure]

Red is very busy !
link to article :
1960s Concept to Study Giant Planets

Robert “Red” Jensen removes a major component from an aircraft mold for assembly of a prototype of an atmospheric probe as Justin Hall watches at NASA’s Armstrong Flight Research Center in Edwards, California.
NASA/Steve Freeman

 

[thenated0g]

@Red you think Justin#2 will come to sunset?

 

[Red]

@Red you think Justin#2 will come to sunset?

Yes both are planning and looking forward to it.

 

[thenated0g]

Awesome. He had some cool planes. Can't wait to see what he brings.

 

[jure]

Radian pitcheron mod , first fitting tests.

Servo holder inserted into the fuselage:

the four 3D printed parts

 

[j ferguson]

Milling solid balsa airfoils. Has anyone tried it?

Except for some minor tweaks, I've completed the SwitchBlade 300 replica (at 2.2 lbs) but have become convinced that it might be better to learn how to fly a tandem thin-wing pusher with controls limited to elevons on the fore wing with a simpler and lighter version. My idea would be to use a 20mm CFRP tube for the fuselage and provide 3d printed attachments for battery, esc, receiver, wings, vertical fins, stabilizers and motor which clamp onto the tube. This way I can easily adjust CG and perhaps discover hoow sensitive it actually is on a tendem wing. I'd make it same size as the SB 300 but use solid balsa for the wings and fins. If I don't do landing gear and hand launch I can save weight and the need for another servo.

Assuming that it would be better if the wings had suitable airfoils, I wondered if anyone had milled airfoils on balsa. I have a 6040 CNC router and the software to do 3 axis milling and the vacuum table to hold the boards while I cut the contour of the airfoil on top. I'm guessing that cleaning up the leading edge and leaving the bottom flat (no camber) would be adequate..

Or I could just sand nice leading edges on the 1/4 inch balsa boards, glue tapered trailing edge on aft wing and leave fore wing flat until the elevon attachement point.

I could also 3D print the wings with PolyLight, but I've found that it is very difficult to get an adequately stiff structure much lighter than double the weight of solid balsa of same dimensions. I suppose I could do a composite of forward part printed with balsa trailing edge. If 3D printed, I'd need at least one spar. My guess is the balsa wings wouldn't need spars.

And it's certainly true that a built-up balsa wing could be much lighter, but then this practice plane is sort of to learn how to fly a heavy tandem wing.

Is this nuts?

John

 

[Doc J]

Milling solid balsa airfoils. Has anyone tried it?

Except for some minor tweaks, I've completed the SwitchBlade 300 replica (at 2.2 lbs) but have become convinced that it might be better to learn how to fly a tandem thin-wing pusher with controls limited to elevons on the fore wing with a simpler and lighter version. My idea would be to use a 20mm CFRP tube for the fuselage and provide 3d printed attachments for battery, esc, receiver, wings, vertical fins, stabilizers and motor which clamp onto the tube. This way I can easily adjust CG and perhaps discover hoow sensitive it actually is on a tendem wing. I'd make it same size as the SB 300 but use solid balsa for the wings and fins. If I don't do landing gear and hand launch I can save weight and the need for another servo.

Assuming that it would be better if the wings had suitable airfoils, I wondered if anyone had milled airfoils on balsa. I have a 6040 CNC router and the software to do 3 axis milling and the vacuum table to hold the boards while I cut the contour of the airfoil on top. I'm guessing that cleaning up the leading edge and leaving the bottom flat (no camber) would be adequate..

Or I could just sand nice leading edges on the 1/4 inch balsa boards, glue tapered trailing edge on aft wing and leave fore wing flat until the elevon attachement point.

I could also 3D print the wings with PolyLight, but I've found that it is very difficult to get an adequately stiff structure much lighter than double the weight of solid balsa of same dimensions. I suppose I could do a composite of forward part printed with balsa trailing edge. If 3D printed, I'd need at least one spar. My guess is the balsa wings wouldn't need spars.

And it's certainly true that a built-up balsa wing could be much lighter, but then this practice plane is sort of to learn how to fly a heavy tandem wing.

Is this nuts?

John

Hey John.

Thin wing Control line FAI competition teamrace planes, and to some degree speed models too have been using CNC milled balsa wings and more recently milled Rohacell etc for some years now with really good results. Probably the substrate would not matter too much.

After the assembly/machining the wing cores are placed in aluminium moulds withthe other parts and fabric and pressed to finish.

This "solid core" technique has also been used, and is still being developed for model sailplane wings too, but tends to be restricted to expensive competition models becuse of the general costs involved.

For small experimental models such as yours, it would be an ideal and very stable solution to use for further development.

To try the advanced construction techniques for my range of models I have what I all a "Development Centre" (Read "Shop") where I try out a lot of ideas like this, just as you guys do in your shops. Not every; in fact not many ideas make it past the development trials but some do and they have led to other advances that are now becoming unique to my model designs.

Carry on the good development!

Its funny what makes some of us tick!

Doc.

 

[j ferguson]

Hi Doc,
Thanks much for this information. It did occur to me that I could make a female form of the upper side of the wing to hold it while I milled the bottom. I may make a fixture to locate the raw balsa on the vacuum table so I don't have to go nuts lining each one up. It's funny about shops. It's taken many years to get to the point where I can do almost anything I want (within the normal range of what I generally do) without first going out to buy additional tools.

 

[jure]

progress on the Radian pitcheron.
almost ready for the maiden flight.

 

[Wayne]

Woohoo - That is an interesting conversion. Looking forward to hearing how it flies. I'm guessing it will be pretty similar to stock, but more responsive.

 

[jure]

and here it is , the maiden flight of the Radian pitcheron.

Using four custom designed 3D printed PLA parts.
Two HS-225BB 27g servos drive the pitcheron mechanism.
Wing TE deflection is +/- 10 mm at the wing root , with +/-100% aileron command.
Functional Elevator. Rudder is inoperative.
On a switch , there are three spoileron positions , { 0.0 , 2.5 , 5.0 } mm up at the wing root TE .

Compared to a standard Radian , it feels like riding a wild horse ( ... with no name ) .

Needs more fine tuning, I hope to be able to demonstrate axial , drill bit rolls ( ™ ® by Kasra ).

Also, want to see if getting rid of the motor , one servo and one push-rod , it can be a fine sloper.
Will have to take care of the CG , perhaps with a Pinocchio nose with ballast at the tip .

 

[gp49]

and here it is , the maiden flight of the Radian pitcheron.

Using four custom designed 3D printed PLA parts.
Two HS-225BB 27g servos drive the pitcheron mechanism.
Wing TE deflection is +/- 10 mm at the wing root , with +/-100% aileron command.
Functional Elevator. Rudder is inoperative.
On a switch , there are three spoileron positions , { 0.0 , 2.5 , 5.0 } mm up at the wing root TE .

Compared to a standard Radian , it feels like riding a wild horse ( ... with no name ) .

Needs more fine tuning, I hope to be able to demonstrate axial , drill bit rolls ( ™ ® by Kasra ).

Also, want to see if getting rid of the motor , one servo and one push-rod , it can be a fine sloper.
Will have to take care of the CG , perhaps with a Pinocchio nose with ballast at the tip .

Try some Radian pro wings! you could mix some wild things with a 6 servo wing!

 

[bubbasks]

Nothing crazy but saw these fly a couple weekends ago and looked like lots of fun. Just finished mine up.

 

[Red]

Nothing crazy but saw these fly a couple weekends ago and looked like lots of fun. Just finished mine up.

You will love it, fantastic flyers!

 

[bubbasks]

You will love it, fantastic flyers!

Excellent little plane. Got about 45min on it today. Very fun