Kristoffon
Well-Known Member
I'm taking the liberty of posting this here instead of the build log section because I don't wish to miss on anybody's thoughts and criticism.
Aircraft choice
About a year or so after I learned about this madness of ordinary people building flying machines the thought had settled that I was going to build one. After researching every aircraft available in kit or plan form three times over I decided I was going to build from plans, mostly because importing stuff here is difficult and expensive and I wouldn't be able to afford an RV or similar kit. I also decided I wanted an amphibian to make the most out of the plane. Of the three or four aircraft that met those requirements the Osprey is the only one with an active builder community and support so it was the easy choice. I bought plans April/2010 and they languished due to RealLife® problems until a couple months ago.
Glue joint strength testing
Laminating longerons 10/08/2012
The first two attempts at the upper longerons were discarded because they didn't take the required shape. Later I was told I wasn't supposed to take them out of the table until the whole side was done, but it still took a HUGE force to make them do the sharp bend on the right and I wasn't comfortable with building it stressed like that. For reference I wasn't able to put the pieces on the formers by myself, somebody had to slip c clamps over it while they were being held and then the clamps would pull the last inch or so. I rebuilt them from 4 x 1/4in pieces instead of 2 x 1/2in and those held the shape OK.
Close up of the step before being glued
Both sides done 11/09/2012
The corner blocks on the back half weren't supposed to be there, only plywood triangles. I put them in by mistake in reading the plans but I don't regret it, negligible weight gain for a lot of strength.
In 3D now 17/09/2012
It's a huge effort to get everything to fit right. Every little part has to be sanded and sanded and sanded through trial and error then it gets sanded too much and off to make another one. Sanding off the excess glue is also very time consuming, it can easily take a whole day to sand off the previous day's glue drips and blobs.
Fuselage skeleton done 24/09/2012
Gluing aft floor, front floor already glued 06/10/2012
The hump on the top is to install a water drain. The floor sections had to be glued together because the largest plywood sheets I had access to didn't entirely cover them as the plans originally intended. It took a couple days to engineer a way to get good scarf joints on plywood (best solution so far is clamping them between two wood blocks with the correct angle set, then sanding off the edge leaving a 10:1 slope) then a couple more days learning to join sheets properly - they have to be glued at table level, anything raising them over the table makes it impossible to clamp them together and they just slide off.
Floors done, putting the diagonals in place 31/10/2012
The plywood sidings on the corners in the right picture glue to the battens below the floors which for some reason I didn't take pics of. Another very time consuming task was cutting (and gluing) the plywood triangles on the sides of the triangle blocks, forming them to the exact shape of the blocks they cover. That should've been done before the fuselage sides were put together but I hadn't received the material yet.
The square sheets joining the diagonals on the back also glue to the battens below the floor.
The corner blocks on the sloping sections of the floor were specially hard to get right because they must have the same slope on their bottom and that has to be achieved through trial and error.
Those below-bottom battens were tricky to glue in place too because the floor, being thin, sags a bit on the middle so temporary supports had to be made to get it flat. Then they tended to slide down the floor because they couldn't be clamped down with the clamps I had and I didn't want to nail them and ruin the beautiful plywood sheet so they were kept in place with weights only.
This was a long stretch of slow and unrewarding work.
Gluing top aft covering 01/11/2012
Again only weights keeping the plywood on top of the inside battens, no nailing anywhere.
Building underside ribbing to form the bottom shape of the fuselage 07/11/2012
Earlier today. Note the battens I mentioned before. Getting the longitudinal sheet into shape. That's deceptively time consuming work, it has to be sanded here and there until it fits the exact curve of the fuselage, placing it in position in between each attempt. Then sand too much at one spot and all the others must be re-sanded to match. Hopefully I can glue them all tomorrow and start on the vertical stabilizer still this week.
Final thoughts
I'm pretty satisfied so far. This aircraft is overbuilt and that makes me happy. According to the designer it is necessary strength to take shocks from water operation. I have seen the tail cone of a wooden sailplane with paper thin plywood that suffered a stall on landing and that didn't inspire any confidence at all. No wonder it snapped off just from hitting the ground hard. That won't be happening here.
It's funny how the simplest things can take a lot of work. One drawing, one sentence in the builder's manual can take a week to do, or more.
I'm hoping things will go quicker from this point on, I believe most of the detail work is done. The wing ribs may be many but they can be cut all at once, that didn't apply to the fuselage pieces so far. I expect making the wing spars will be a major effort but I already made mistakes with the longerons so they won't take two weeks to get done, I hope.
I'll be making updates this thread once a week or so as progress warrants, at least for the time being I'm working almost full time, 5-6 hours/day, on the aircraft.
Aircraft choice
About a year or so after I learned about this madness of ordinary people building flying machines the thought had settled that I was going to build one. After researching every aircraft available in kit or plan form three times over I decided I was going to build from plans, mostly because importing stuff here is difficult and expensive and I wouldn't be able to afford an RV or similar kit. I also decided I wanted an amphibian to make the most out of the plane. Of the three or four aircraft that met those requirements the Osprey is the only one with an active builder community and support so it was the easy choice. I bought plans April/2010 and they languished due to RealLife® problems until a couple months ago.
Glue joint strength testing
Laminating longerons 10/08/2012
The first two attempts at the upper longerons were discarded because they didn't take the required shape. Later I was told I wasn't supposed to take them out of the table until the whole side was done, but it still took a HUGE force to make them do the sharp bend on the right and I wasn't comfortable with building it stressed like that. For reference I wasn't able to put the pieces on the formers by myself, somebody had to slip c clamps over it while they were being held and then the clamps would pull the last inch or so. I rebuilt them from 4 x 1/4in pieces instead of 2 x 1/2in and those held the shape OK.
Close up of the step before being glued
Both sides done 11/09/2012
The corner blocks on the back half weren't supposed to be there, only plywood triangles. I put them in by mistake in reading the plans but I don't regret it, negligible weight gain for a lot of strength.
In 3D now 17/09/2012
It's a huge effort to get everything to fit right. Every little part has to be sanded and sanded and sanded through trial and error then it gets sanded too much and off to make another one. Sanding off the excess glue is also very time consuming, it can easily take a whole day to sand off the previous day's glue drips and blobs.
Fuselage skeleton done 24/09/2012
Gluing aft floor, front floor already glued 06/10/2012
The hump on the top is to install a water drain. The floor sections had to be glued together because the largest plywood sheets I had access to didn't entirely cover them as the plans originally intended. It took a couple days to engineer a way to get good scarf joints on plywood (best solution so far is clamping them between two wood blocks with the correct angle set, then sanding off the edge leaving a 10:1 slope) then a couple more days learning to join sheets properly - they have to be glued at table level, anything raising them over the table makes it impossible to clamp them together and they just slide off.
Floors done, putting the diagonals in place 31/10/2012
The plywood sidings on the corners in the right picture glue to the battens below the floors which for some reason I didn't take pics of. Another very time consuming task was cutting (and gluing) the plywood triangles on the sides of the triangle blocks, forming them to the exact shape of the blocks they cover. That should've been done before the fuselage sides were put together but I hadn't received the material yet.
The square sheets joining the diagonals on the back also glue to the battens below the floor.
The corner blocks on the sloping sections of the floor were specially hard to get right because they must have the same slope on their bottom and that has to be achieved through trial and error.
Those below-bottom battens were tricky to glue in place too because the floor, being thin, sags a bit on the middle so temporary supports had to be made to get it flat. Then they tended to slide down the floor because they couldn't be clamped down with the clamps I had and I didn't want to nail them and ruin the beautiful plywood sheet so they were kept in place with weights only.
This was a long stretch of slow and unrewarding work.
Gluing top aft covering 01/11/2012
Again only weights keeping the plywood on top of the inside battens, no nailing anywhere.
Building underside ribbing to form the bottom shape of the fuselage 07/11/2012
Earlier today. Note the battens I mentioned before. Getting the longitudinal sheet into shape. That's deceptively time consuming work, it has to be sanded here and there until it fits the exact curve of the fuselage, placing it in position in between each attempt. Then sand too much at one spot and all the others must be re-sanded to match. Hopefully I can glue them all tomorrow and start on the vertical stabilizer still this week.
Final thoughts
I'm pretty satisfied so far. This aircraft is overbuilt and that makes me happy. According to the designer it is necessary strength to take shocks from water operation. I have seen the tail cone of a wooden sailplane with paper thin plywood that suffered a stall on landing and that didn't inspire any confidence at all. No wonder it snapped off just from hitting the ground hard. That won't be happening here.
It's funny how the simplest things can take a lot of work. One drawing, one sentence in the builder's manual can take a week to do, or more.
I'm hoping things will go quicker from this point on, I believe most of the detail work is done. The wing ribs may be many but they can be cut all at once, that didn't apply to the fuselage pieces so far. I expect making the wing spars will be a major effort but I already made mistakes with the longerons so they won't take two weeks to get done, I hope.
I'll be making updates this thread once a week or so as progress warrants, at least for the time being I'm working almost full time, 5-6 hours/day, on the aircraft.
