Semi-scale ASH25
Posted: 23 Dec 2019, 23:23
Well it had to happen. After 20 years of joyous flying in all conditions in every corner of the country, I stupidly stuffed my 4m ASH25 into the ground last August. Nasty turbulence at Leek turned a fast pass at +3m height into a sudden stop at -25cm. A photo in RCM&E shows the carnage.
The bits (and there were many) have been in the workshop long enough. Looking over them last week, I decided it's worth fixing as the wings are virtually unscathed. So all I need to do is make a new fus.
I'll change a few things just to add interest, the main one being to mold the fus using the lost foam technique. I made some fuselages like this decades ago but they were pretty primitive. Hopefully I can refine my technique. I'm inspired by Roo, and how believably fast he makes his fuselages. I'm also determined to do a better paint job than my usual satin finish - I want GLEAMING! And I'm going to vac-form a canopy too - I always meant to do one for the ASH25 but had so much fun flying it I never bothered.
First question - I'm planning to make the fuselage plug from XPS (extruded polystyrene) foam, the kind available in 6mm - 30mm thick sheets for electric underfloor heating. Is this the best stuff to use? I like its small-cell texture and it shouldn't break off in lumps like EPS (expanded polystyrene).
Second question - can you hot-wire cut XPS for foam wing cores? If so I'll buy plenty for future foam-veneered wing projects.
Meantime I've drawn up a new fuselage plan and practiced some composite layups. I plan to use 2 layers of 200gsm twill glass cloth either side of 175gsm Diolen - an aramid cloth similar to Kevlar but cheaper. First samples seem great. Light and stiff but with an extra resilience due to the Diolen. The Diolen cloth is a nightmare to cut (it just fluffs up!) but it wets out OK and seems to bond well to the glass. It cuts better after the epoxy has set.
I'm a dead slow builder as I overthink stuff and have very little spare time but I hope to make a start on the foam plug before new year.
Rog
The bits (and there were many) have been in the workshop long enough. Looking over them last week, I decided it's worth fixing as the wings are virtually unscathed. So all I need to do is make a new fus.
I'll change a few things just to add interest, the main one being to mold the fus using the lost foam technique. I made some fuselages like this decades ago but they were pretty primitive. Hopefully I can refine my technique. I'm inspired by Roo, and how believably fast he makes his fuselages. I'm also determined to do a better paint job than my usual satin finish - I want GLEAMING! And I'm going to vac-form a canopy too - I always meant to do one for the ASH25 but had so much fun flying it I never bothered.
First question - I'm planning to make the fuselage plug from XPS (extruded polystyrene) foam, the kind available in 6mm - 30mm thick sheets for electric underfloor heating. Is this the best stuff to use? I like its small-cell texture and it shouldn't break off in lumps like EPS (expanded polystyrene).
Second question - can you hot-wire cut XPS for foam wing cores? If so I'll buy plenty for future foam-veneered wing projects.
Meantime I've drawn up a new fuselage plan and practiced some composite layups. I plan to use 2 layers of 200gsm twill glass cloth either side of 175gsm Diolen - an aramid cloth similar to Kevlar but cheaper. First samples seem great. Light and stiff but with an extra resilience due to the Diolen. The Diolen cloth is a nightmare to cut (it just fluffs up!) but it wets out OK and seems to bond well to the glass. It cuts better after the epoxy has set.
I'm a dead slow builder as I overthink stuff and have very little spare time but I hope to make a start on the foam plug before new year.
Rog