Hanno Pretner Curare build

RCM&E 1977 Article


Click on any photo for a hi res version

16. New Canopy

16. New Canopy
The original canopy was a salvaged Xtra Wot one cut down to suit, but it never really fitted problerly and I have lost it a couple of time mid flight when the tape holding it on failed. So I decided on a  new one made from pink foam. Simply carved and covered in glass cloth.

15. Completed fuselage
Ashloc conectors for the servos and a reversing Y lead for the flaps. Tail image shows the general arrangements  for elevator and rudder connections.

14. Completed Wing
Completed wing, its a bit busy in there with 4 servos and 2 retract units. The dark blue film is solarspan, whist the lighter blue is some 20 year old solarfilm I've had in my film box.

13. Completed Fuselage
Fuselage was sprayed and given a cote of Klasscote clear epoxy, all graphics were made with my vinyl cutter.

12. Completed fuselage
More work but not many photos I'm afraid. Completed fuselage with the wing farings from 3/8 triangle stock & filler. The entire fuselage was then covered with 1oz glass cloth, (stuck down with Bucks Composite epoxy system) and painted with the first coat of white primer / filler.
3rd image is the wheel well sprayed anf the wing ready for covering.

11. U/C fitting
Before I finally cut the wheel wells out a quickcheck that my previous measurements are correct. I then cut the wells for the wheels and the U/C spring leg. The entire centre section was covered with 1oz glass cloth when the wing joining tape was done. The servo slots visible are for the flap servos, with similar further outboard for the ailerons.

10. U/C fitting
Fabrication of the undercarriage mounts, I'm using E-Flight electric retracts. The second image shows the wing cut out, the plates attach to the top skin and are glued in place with Gorilla glue to fill any gaps.

9. Wing seating & U/C trial fit
A bit of trial and error here, becuase I'm not using a tricycle undercarriage, I'm having to move the main U/C forward, but still need sufficient height on the wheels to clear the prop. Setting up on a few books with the prop on gives me the height of the undercarriage, and the position in the wing.

8. Wing joining
Wing joining using my proven method to get a straight wing.
Draw a line thtough the centre of each wingtip, and tack glue parallel strips of balsa, high enough to give the desired dihedral, weigh down, you know know that the wing is flat, and each wing panel is parallel.
The third image shows the error in the wing panels, this can be filled at the root. Rather this than have the tips twisted byt he same amount. By the way, these panels are very good. my Extra Wot ones were close to 6mm out at the roots.

7. Fuselage assembly
I fitted the enging to it's mount and built up and shaped the cowl around it.

6. Tail & Fin
Tailplane prepped in the same way as main wings, and the fin section was built over the plan before being fully sheeted.

5. Wings
Control surfaces cut out, and faced with 1/4 balsa. I have doubled up in the hinge area with a 1/4 piece pre fitted. This was done on both the wing & control surface.

No provision has been made yet for the brake, but I'm thinking I might build the flap without one, and use something like .5mm glass or carbon sheet stuck to the flap. This of course would mean a high (.5mm) area over the flap, but will make building & finising a lot easier. If I use carbon I could include it in the colour scheme.

4. Wings
Wings arrived from Foamwings Barry has done a supurb job with these. Its going to be a real shame to cut into them.

3. Elevator Servos
I prefer to have a servo close to the elevators ie no long control rod. I know its not to plan, but I dont have 1970's servo anyway nor a Webra Speed 61.

This is a bit tricky on this model, because of the anhedral on the tail. The geometry is not suitable for a single servo, so I've had to use 2. The servos are Savox SH-0257. They have over 2Kg torque each so should be OK.

They are positioned each side one with an arm up and the other with the arm down so the take off is in the same place for each elevator half. There will be a ply plate to support the servo

2. Fuselage assembly
Fuselage in the jig, the formers are glued using Araldite 24 hr, note the number of squares and clamps.

I've brough it indoors so the epoxy can reach a fuller cure than in the shed. Its getting cole out there!.

1. Fuselage bits
Getting ready for the winter build season.

Just ordered the Curare plan from myHobbyStore, and got a whopping 88p subscriber discount. That'll buy some biccies while I study form.

Wings are on order from Barry at Foamwings - he already has the templates on file.

Just starting cutting out some bits.