Building Popsie

[sparks59]

oh, and I added a strengthener around the main U/C mounting, which went in at the same time as the epoxy. I made it up from two 1/16 sq spruce spars capped with a strip of 1/16th ply,  see previous photo and below.  Then set about the front end, I'd cut all the ply pieces following the layout of the 'Replikit' but making the pieces straight for simpler cutting and easier to achieve good tight slots for the joints. So, armed with only a few pins and a half gallon tub of PVA glue....

 

 keen eyed viewer will notice the next faux pas. Yes, I did cut out the hole in former, before checking the motor aligment etc. so had to stick it back in, with a strengthener behind the former to take the motor mount screws, one of which happened to fall in the 'hole'

[sparks59]

here's more evidence of 'la boo-boo'

then added the gussets atop the U/c legs. I'd also added a cross board for the receiver mount / battery hatch stop

On with the side sheeting..

 

 

Next to add the front fuse side cheeks the little trim bits on top of the nose to accept the top sheeting, which is a right fiddly section to fit.

 

I’ll finish trimming it to shape and glue it up later, then will do the bottom and lower sides, and finally the battery cover. On the plan, the cover is made up of 3 x 3/16 sheets that are glued and shaped, way over-engineered for a lecky plane so I’m going to do it a little differently and sheet the cover.

 

At this stage, the thinking about finishing was seriously a bumble bee yellow and black design covering. Even thinking of doing it with hoops, though that may be a bit of a devil to get looking good. So it could (and did) finish up with a simpler yellow / black design.

 

[Stephen Grigg]

Really enjoying the build,my Mamselle undercarriage has fallen off the fuz and is very difficult to get at it,so your attention to fixing theU/C was good planning

[sparks59]

Posted by Stephen Grigg on 16/07/2010 20:45:49:

Really enjoying the build,my Mamselle undercarriage has fallen off the fuz and is very difficult to get at it,so your attention to fixing theU/C was good planning

 

 Hey Stephen, the combination of desert stand and my dubious flying finesse are well known to me, that's the reason for making sure the u/c is beefed up! I have straightened the legs on the microsquire and the monocoupe too many times, but, thankfully, the mountings are still ok! It's No good skimping on stuff thats going to suffer bludgenation!

sparks

[sparks59]

Onward with the side cheeks, upper curved sheeting, and the underside. I decided to plank it with 3/16 and 1/8th strips, looks a bit like Fido's breakfast here, but worry ye not, it all sands up lovely.

 

I wetted the 1/16th sheet on top and held in place with elastic bandits until dry, then out with the PVA  and back on with the bands until dry.

 

Deviation from stock here. I made two removable covers. Held in place with magnets. This is to allow some more access and flexibility with battery / equipment position. And the stock rear hatch is a whacking great chunk of wood, so i decided to see if i remembered anything from Tech. Drawing all those years ago! Those double curves are testers, but i think it came out ok. Well it will after sanding!

 

 

watch this space!

 

sparks

[Stephen Grigg]

When planking do they butt together edge to edge Sparks

[sparks59]

Posted by Stephen Grigg on 17/07/2010 22:07:24:

When planking do they butt together edge to edge Sparks

 Yes, just plain butt joints. You'll note that I cut the pieces wider at one end to accommodate the taper. I also chamfered the mating faces to allow for the curvature. A bit fiddly but worth investing a bit of time to get it right, and the end result is quite strong.

[Bruce Richards]

Sparks, I must say your building is very neat. I hope mine turns out half as good as yours looks.

[sparks59]

Thanks for your comments Bruce, good of you to say, but i'm sure that my camera makes things look better really.

 

Next on the agenda is the nose cone assembly and sanding to shape. I added two pieces of 16^th between the 3/16^th slabs as I felt that the size differential was too much and might finish up with an odd shaped cone if I didn't get it exactly right while sanding in 3d. It was a good choice as the cone sanded up well.
 
Then cut out the vents, chamfered the inside to clear the motor, magnets / locating pegs still to add.

 

photo to follow...

 

sparks

[sparks59]

Ok, I found out a few missing snaps of the front end build, so here goes;

 

Battery hatch detail

 

 

and this is inside of the cover, during construction, the 5 min epoxy isn't pretty but not visible on the outside.

 

here's the blank cone / cowl

 

ready for final trim / sanding..

 

need to dig for a few more pictures of the underside / side cheeks, I know I had some!

 

sparks

[sparks59]

there we go, seek and ye shall find. This photo of the underside tongue in 3/16th balsa should have been inserted about four posts ago. nevermind, i'm sure (well ok, I hope)you guys will forgive me

 

above shows the correct orientation, and below is the reverse side of the cone, duly excavated to clear the outrunner case, location dowel pegs glued in, magnet still to add.

The rear face is 1/16th ply, 1/32nd would probably be fine if you are looking to diet, in fact it probably doesnt need anything really as it doesnt need to be taken on and off in use. Though it doesnt matter to have a bit of weight up front, to help with the CofG. Especially with my tailwheel construction!

 

sparks

[sparks59]

speaking of the tailwheel...here's the parts, well some of them. Although the arrangement on the plan is wrong, well its not as I built it, the actuator is nearer to the top, so the dowel is inverted here.

This is how it fits together,

1st the actuator arm on the tailwheel steering shaft / pivot

 

Then the thrust face and lower bearing;

Then the thrust face and lower bearing; again, the final assembly came out a little different as the round thrust bearing (shown on top) finished up below the rectangular to bearing, and a plain top plate, with a  bevelled ocation hole fitted on top, between the fuse sides. Confused, yes, so am I.

[sparks59]

Looking through these photo's is a reminder of how much work went into the tailwheel. If you fly off a hard surface or short grass, you probably dont need this, but on soft sand, its near impossible to ROG without the tailwheel control as a fixed wheel or skid has a tendency to dig in a little, hence the rudder has no authority. Plus, if you can be bothered, I think it looks better.

 

I'll post a few more pics which show the assembly better, just in case any one is up for a challenge. There are lots of improvements you could make to this if you can get hold of the right sort of parts, I made do with what I had in the drawer.

 

Underside view, note the wire is epoxied into a hole I drilled into the 1/8th ply shaft.

 

external port side view

Above, Top view, before the upper plate is installed

 

Below; as above looking from the front

 

and below, with the control rod connected to the short side of the arm and top plate fitted, flush with the 3/16th fuse sides.

Good to get that bit finished.

 

sparks

[Tim Mackey]

Nice work sparks...and a great blog with plenty of good pictures

[sparks59]

Thanks Tim,

As the old saying goes, a picture is worth a thousand words. Pleased you like the blog.

sparks

[Stephen Grigg]

I like you attention  to detail,re theNose cone and the little personal touches you add to your model

[sparks59]

Cheers Stephen.

 

Sometimes I attend to little details and miss some glaringly obvious gaff's on the bigger ones though , eg the motor cut out, all fixed and no longer visible though...

 

I just like to have a look at the plan before I start ripping balsa and think if there are some things that could be made better, easier, stronger, more accesible. It a dangerous thing sometimes, especially if you modify something that you may need later on in the build.

 

 there's another coming up soon on the Popsie, with a further mod on the tailwheel! I did say it could have been better didn't I? No biggie, but the workaround involved another 9g servo and rod.

 

sparks

[Jim Newberry - Nuviation Ltd.]

Looking good Sparks! I had been looking at the Popsie plan with a view to building one myself. In the end I decided to build my own design based around the Popsie idea (just about ready for its first crash once the wind dies down in Warwickshire!) but am thinking of building a scaled up Popsie one of these days so will be following your blog from now on!

[sparks59]

Thanks Jim,

 

Good luck with the maiden of your self made plane. I'm sure it's a bit of a worry!

 

Bruce has started a Popsie x2 or 2x thread on hear as he is going to do a Supersize Popsie . I tried to paste the link in but it got my browser all hung up, but a seach for Popsie will find it ok.

sparks

[sparks59]

Ok, where was I ,

Here's the entry from my daily blog....not really progress stuff, more like general stuff for discussion, ponder and mirth.

Fitted a couple of dowel pegs to locate the cowl onto the front bulkhead, will add a magnet for security but its nice and tight at the moment. Just got to sand the front end a bit to blend the shape a bit more before any tarp' goes on.

Got the motor hooked up to the esc (I used an 18A as i think the 12A that I was planning to use might be stretched if i need full wallop) and an XT60 battery plug soldered on.

The motor is bolted in temporarily, but i think it will have to come out again so that I can space it off a few mm to clear the nose cone. It must have been the extra couple of layers I added in to get a nice curvature!

I test ran it to ensure the rotation was correct by hooking up the battery and plugging it into the receiver on the Microsquire. I slid on a prop that was sitting in the bottom of the drawer, about a 7 x 5 and gave it a whizz.

Stone me!  it blew all the balsa dust, shavings, and everything not made of lead or nailed down, straight off the dining room table - loads of wallop from the little 28-20 hacker copy motor (from HK). And it was going the right way! Better result than England had against the Yanks.

 

At this stage, I put it all on the scale and it showed around17oz, (with 1000maH 3s battery, receiver, servo's, wheels etc but covering, control horns and wheel collets still to go on).

Put the numbers into Web-o-calc and it looks like its going to be a bit of an handful, ie a tad fast. Problem with web-o-calc is that it doesnt have data for the planned 8 x 3.8 prop.

Nothing to be done about it unless i can get the weight down to a pound, to bring it into the trainer/parkflyer category. Or build a bigger wing with more lift. Anyway, I still think it will be ok and I dont want to sand it away too much and lose the inherent strength. I might put holes in the rudder and possibly the elevator to reduce the tail weight a tad without affecting strength or performance.

 

Got to nail the servo's in and get the covering done now!

 

I need not have worried about the weight or the web-o-calc, but just thought I'd share the apprehensive moment during the build with you guys.

sparks

 

.

[Big Bandit]

Hi Sparks,

 

Very nice build, I'm sure it will fly as good as it looks. I have a few weeks off in August and September, so I've ordered the plan off the X list, loadsa balsa, ply, motors and RC gear in the shed, so it looks like game on. See if I can make as neater job as you have.

 

Cheers,

 

Chris.

[sparks59]

Hey Chris,

Thanks for your comments. It's turned out fairly well and i'm happy with the result. The blog is behind real time, so I can tell you already that it flies really well.

 

I look forward to seeing your build log when you get the plan. It's a really good feeling getting ready for a new project.  Are you going to build for lecky or IC?

sparks

[sparks59]

 

 I had to take the motor out again and space it off by a few mm (using 4mm nylon nuts) to get the prop clear of the nose cowl. Then had to dish out the back of the cowl a bit more with a wad of sandpaper to clear the outrunner cylinder, all looks and fits really nice though.

 

The prop shaft is a bit off centre but I didn't want to weaken the structure with another set of holes so I left it as is, take care if you are building one!

 Drilled out the cowl vents and sanded to shape. I started out with D shaped vents (a la Cessna style) but it didn't quite look right so i rounded them, and I prefer the shape over the rectangles.

 

Sanded the bits up and realised that i still had to make a leading edge fairing for the cab roof. The plan shows a big lump of scrap balsa, anyway I didn't have a srap lump so big to hand so I made the fairing up from strips of 1/8th stepped to shape around the leading edge, then, when glued, whittled and sanded to shape, inside and out.

 

Also spent ages deliberating over the colour scheme and in the end i couldnt get the 'jolly' yellow and black scheme out of my head. For me, Popsie might be a classic but the old girl is still going to be a fun sorta character! I dont want it to be sombre. i want it to be something that shouts out hey, look at me! I'm the chubby bumble bee!

 

 

 

[sparks59]

Covering going on!

 

Fin done, sitting in place for the photo.

 Then the tailplane covered and glued to the fin, note the artistic use of kidney bean cans, pins and cotton to keep the whole lot square. It's not pretty, but it works.

 

 

[sparks59]

Forgot to mention, the control surfaces are hinged with the solarfilm tarp'. strips about 3/8th wide at either side top and bottom, with a square of matching colour over the black / yellow surfaces. needs a bit of care but works really well. If you want to eliminate the gap altogether, full length hinges can be done, But I prefer the look with a small gap and there's less work for the servo to do too.

 

Wing covered, leading edge fairing made, but not yet sanded to shape.

 

 Time for bed!

 

Sparkout