Aero-naut A-10

[Gary Binnie]

Managed to sneak out to the shed for a couple of hours.

 

The 6 x 5 props arrived and I ran the set up in the garden, 200 Watts this time, much better. Neither the battery (1300 3S F5J), speed controllers or motors got remotely warm. The plan shows cooling holes in the fuselage and plastic NACA ducts are provided but I will probably go without but make sure that there is a vent somewhere, I could use the gun as an inlet.

 

Finished the first aileron and added the facing strip to the second one, a little job that needed doing was to sand down the wing facing strip with the aileron in place.

 

Started on the wing tip blocks which I wasn't looking forward to but it's going ok so far.

 

1. 6 x 5 swoopy carbon fibre props, a set of four, two CW, two CCW as they are for drone racing.

 

 

 

2, 3 and 4. 18.5 Amps and 204 watts at full throttle, 8.5 Amps and 94 Watts at half throttle. 1200 milliamps used in an eight minute run.

 

 

 

 

 

5.  Aileron from yesterday with tape removed, I left the facing strip oversize, top and bottom and both ends.

 

 

6. Done apart from covering.

 

 

7. A little job that I almost forgot was to sand the wing facing strips flush with the surface, I did this without the ailerons on my Phase 6 and caused terrible dips. The 'V' formed by the two tapered faces to allow down movement can be clearly seen.

 

 

8. Turned over and did the same job on top. I will have to trim the ends a bit more for clearance (I normally go for 1 mm each end without covering).

 

 

9. Easier to see the oversize facing strip on the other wing.

 

 

10, 11 and 12. Both ends of the wing were left roughly trimmed, I used my long sanding bar to get a flat end rib face.

 

 

 

 

13. The wing tip blocks are pre-cut in plan view and made from very hard balsa which they have to be because they will be quite thin and concave at the trailing edge. They weigh 20 grammes each.

 

 

14. They need to be carved and sanded to the sections given on the plan.

 

 

15. As the wing structure is relatively fragile I want to carve and sand the tip blocks as close as possible to the final shape before gluing them on.

 

 

16. I bought a drum sanding set not long ago, really handy in a cordless drill and can also be used freehand.

 

 

17. Clamped the first block and started to trim away the concave area at the rear.

 

 

18. Some razor planing and sanding has lost 7 grammes already, to be continued...!

 

 

 

 

 

 

[Gary Binnie]

Just a short building session today, had to renew car insurance and put a new BBQ together this morning.

 

Finished the second aileron.

 

More wing tip block work, tricky things to hold and plane without fingers getting carved as well!

 

I carved and sanded them down as far as possible then glued them to the wings with the lower surface flush so that the remaining sanding is on the convex side (top).

 

1. One of the blocks was slightly short in chord so I added wood at the trailing edge and soaked it in CA to harden.

 

 

2. Ready to glue to the wing, they weigh 10 grammes each and are almost symmetrical!

 

 

3. Glued to the wing with the lower surface flush...

 

 

4. ...which leaves just a small amount of wood to remove on the top surface.

 

[Gary Binnie]

Another productive day, I was hoping to get this finished before the end of lockdown but that's not going to happen. The build is more work than I thought it would be, that's not a problem and there's no rush. I am enjoying it (even the sanding bit!).

 

I'll split today's work in to two posts.

 

First job was to finish sand the wing tips, didn't take long.

 

Next thing to do was fit the engine pylon but the rear fuselage needed more sanding before that, wanted to do it in the garden but it started to rain so dust mask on.

 

Took some time checking alignment of the engine pylon, with no rudder any sidethrust could be difficult to trim out.

 

Engine mounts next, I really didn't like the lack of gluing area on these, I'm sure they would let go in a lumpy landing. For no weight penalty I reinforced them with triangle stock balsa.

 

When the glue had set I fitted the motors and had another look at the CG and weight (covered in the next post).

 

1. Wing tips done.

 

 

2. Rear lower fuselage sanding.

 

 

3, 4 and 5. The engine pylon has some Liteply doublers for the formers, I'm not sure if they're supposed to be reinforcement or just locators.  Part 40 partially blocks the hole for the motor cable so needs a cut out filing. As I couldn't access the lower parts of the formers I glued the doublers to the bottom of the pylon first, nobody will ever know!

 

 

 

 

6. I rubber banded on two rulers, aligned with the thrust lines, and checked the distance from the centre stringer, a small misalignment caused large errors at the front ends of the rulers.

 

 

7. The pencil hatched area is the only gluing surface for the motor mount, I wasn't really happy with this idea. When the glue had set it was possible to flex the mounts up and down. I braced them at the rear with balsa triangle stock, much better now.

 

 

8. Fixing the plastic mount to the Liteply with screws and nuts, the nuts are CA'd so they act as anchor nuts in case the mount needs to be removed but the motor can be easily removed from the mount anyway.

 

 

9. Triangle stock added to reinforce.

 

 

10. Having a look at the trailing edge fairings, these ply parts form the core of a balsa sandwich. Can't build them until the upper rear fuselage sheeting is on. The leading edge between the foam engine nacelles and fuselage will be finished with rounded stock.

 

 

 

11. Front view. The plan shows the mounts inverted, no reason why they can't go this way round, they will hide the motors and cables better.

 

 

12. Not much clearance between the props and fuselage, 6.5 inch diameter is the maximum but props in this size range seem to only be in whole inches. I think I won't do any better than the props I have.

 

[Gary Binnie]

Next instalment: weighing again.

 

As the model progresses I can get a better idea of the total weight and CG.

 

Total weight at the moment (without upper fuselage sheeting and covering) is 1,042 grammes.

 

The CG is around 135 mm aft of the leading edge (aiming for 80).

 

There is scope to move the battery forward, to the front former if needed, and room in the forward fuselage for the receiver and both ESCs.

 

The fins are still  not sanded, I can reduce their weight a lot. That's probably my next job, concentrate on finishing the rear end as far as possible then see what needs shuffling at the front. I'm hoping not to add any nose ballast.

 

1.  Glued the upper centre stringer in, could have done it earlier but it would have made fitting the pylon not so easy.

 

 

2. These plastic parts form the 'core' of the engines, easily cut with a razor saw and scissors.

 

 

3. They have trim lines moulded on the inside, they will need cut outs to half the thickness of the pylon. Should be able to hide the motor wires with these.

 

 

4. Thrown together with all parts and radio gear roughly where they should be.

 

 

5. Total weight at the moment is 1,042 grammes (model balanced precariously on Skyr yoghurt pots). CG is around 135 mm  (finger tip method).

 

 

6. The battery can be moved all the way forward if needed but might be limited by the cable to ESC length, a bigger, heavier battery probably wouldn't hurt, this is only an 1800, I thought it was a 2200.

 

 

 

7. There is plenty of room in this area forward of the wing to house the ESCs and receiver if needed.

 

 

[Gary Binnie]

A day of gentle fettling.

 

Sanded the fins, lost 6 grammes on each.

 

Worked out positions for the ESCs and receiver, I need to wire the motors up and add servo extensions before adding the upper fuselage sheeting.

 

The canopy will definitely become a removable hatch.

 

I haven't got enough motor cable and I need a battery that fits the compartment nicely and is heavier (more flight time!).

 

1. Fins after sanding and adding a couple of lightening holes, the wet and dry paper they are sitting on is to stop them sliding about.

 

 

2. Tail assembly pretty much finished with the fins pinned on in the right place. I considered lightening holes in the sheet but don't think I would have gained much.

 

 

3. The two ESCs will fit here, currently Velcro strapped in but I will revise that because the straps partly block the battery tunnel. The receiver will sit on the clamped Liteply plate just in front.

 

 

4 and 5. Plastic tube guides for the 2.4 aerials, room for a large hamster in this bay!

 

 

[Gary Binnie]

Been a little bit slack lately but still plodding on.

 

The ESCs and receiver are fixed properly now.

 

This morning I was supposed to tidy the shed but I got building instead...!

 

I had to remove my lovely side rails from the battery compartment as they were limiting the width (capacity of the battery), they came out without a fight.

 

The sandwiched engine pylon trailing edge fairings could be made, there was not enough 4 mm balsa in the kit to do this, I suspect it had been raided.

 

Trimmed the plastic engine cores and foam nacelles to fit the pylons, the core pieces need 4 mm cutting out each (half the thickness of the pylons) and the foam just needs a small trim of the slot to fit over the trailing edge fairing (inboard only).

 

Placed the majority of the model on the CG balance rig and set it at 80 mm, with an 1800 Lipo and an AA receiver pack it balances. I plan to go for a 3000 mAh battery which is heavier and place it as far forward as the cables will allow. If it has to have noseweight then I've tried my best, it will still be significantly lighter than the NiMH powered version.

 

Off out for a ride on my motorbike this afternoon, hasn't turned a wheel since the MOT last November.

 

1.  My original idea of strapping the ESCs to the battery rails worked but would have partly blocked the battery.

 

 

2. A Liteply plate glued on strips above the rails fixed that problem.

 

 

3. Radio gear in its final resting place (yep, the fuselage is pointing the other way!).

 

 

4. Making the sandwiched pylon trailing edge fairings.

 

 

5. Having a look at the nacelle fit.

 

 

6. The trailing edge fairings are too long by about 10 mm, the thickness of the nacelle at the the tip. Red hatched area needs to be cut off. It could be left and then trim the foam but the plan shows it cut off, the ply cores are too long (but better than too short!).

 

 

7. Like this...

 

 

8. Trimming the plastic engine cores, they are supposed to fit over the ply motor mounts, not sure if I'm going to be able to do that.

 

 

9. Will have to pay attention to alignment otherwise the 'jet pipes' will be off centre. The plastic cores have balsa strip added to increase the gluing area.

 

 

10. The props just clear, phew!

 

 

11. How it should look at the outboard ends.

 

 

12. On the CG machine for another look.

 

 

13 and 14. Another bench flying session, I really should paint it as it stars in so many model photos!

 

 

 

 

[Gary Binnie]

Back to this after almost a month, had a diversion with finishing a couple of slope gliders and I've even been out flying!

 

Today I extended the motor wires and test run again, max total current was 20 Amps with a power of 220 Watts, it feels and sounds quite scary and I might limit the throttle channel.

 

I should be able to close the fuselage up now and do some more building.

 

There's a short video of a motor run that I need to edit as the file is too big to upload.

 

1. Extending the motor wires with 18 AWG silicone cable.

 

 

2. Soldering the 3.5 mm bullet connectors, the wood is my pillar drill table backing, there's usually a few holes the right size to hold the connectors.

 

 

 

3. Cables fed through the engine pylons and forward to the ESCs.

 

 

4. Another view, watt meter connected.

 

 

5. The new battery weighs 210 grammes and its leads are long enough to allow it to fit here. 

 

 

 

[Gary Binnie]

Edited video of the motor run.

 

This is only to half throttle, the nose is up against a brick wall so I was fairly happy that it wasn't going anywhere!

 

[Gary Binnie]

Had a look at the upper fuselage sheeting, two sheets are provided and are supposed to be cut to dimensions shown on the plan.

 

Doesn't make sense to me as the centre joining line should be straight as there's no section change and they would be 20 mm too long.

 

A job for tomorrow.

 

[Gary Binnie]

Can't say that I'm enjoying this particular stage of the build!

 

After reading the German instructions I cut the sheet to just larger than that shown on the plan.

 

Attached the lower edge of the sheet to the fuselage (CA on the inside, aliphatic on the outside) then let it dry thoroughly.

 

Dampened the sheet (using the sponge from my soldering station) and allowed it to curve naturally then started encouraging it to curve more, tacking it to the formers.

 

Tried to trim a straight centreline, I got close! I will trim it again once everything has hardened fully.

 

Used plenty of clamps and pegs plus a load spreading sheet of balsa and scraped off all the excess glue. Hoping that I haven't glued the load spreader to the fuselage.

 

I won't have the luxury of being able to use pegs when I fit the second side, will be fun.

 

 

 

     

[Gary Binnie]

Second side of sheeting done, if you can afford it go for the fibreglass fuselage!! It could be planked I suppose.

 

Now the sheeting is done I can finish the engine pylons, carve some tail fairings, cover it and fit the wing seat fairings.

 

1. Yesterday's effort dried overnight.

 

 

2. Second side well dampened and pulled in using a combination of masking tape and Velcro straps. CA added to formers internally, the few that I could access through the wing cut out.

 

 

3. I trimmed it to the centreline by using pins and laying a steel ruler between them, in sections of about four inches at a time.

 

 

4. Dampened again and closed up using CA then aliphatic. Done in sections again, pressing down as hard as I dare with an aluminium bar. No creaking or splitting noises so should be ok!

 

 

5. Not the neatest joint but I think it came out better than I was expecting! Used some slivers from the trimming process to fill a small gap, more CA and aliphatic and probably a touch of filler.

 

 

[Gary Binnie]

F5J practise yesterday, a bit chilly.

 

Some gentle balsa bashing today, sanded the fuselage sheeting and added the engine pylon trailing edge fairings and a short length of 8 x 8 mm square strip that forms the leading edge between the foam nacelles and the fuselage.

 

I roughly shaped the leading edge piece to section before gluing it on.

 

What to do next? Choices!! More work on the engine pods, finalise the battery arrangement, fit the nose, make the canopy into a hatch, carve tail fairing.  

 

[Gary Binnie]

This morning I shaped the balsa block tail fairing then had another weigh up/CG check.

 

With the battery fully forward the weight is currently 1145 grammes and the CG is in the region of 85 to 90 mm, recommended  position is 78 to 82 mm.

The CG will move aft with covering but not that much and the weight will increase as well, hopefully will come out at 1200 to 1250 grammes.

 

Aero-naut give 1500 to 1650 grammes flying weight with a NiCad pack. It feels light in the hand (at the moment!). Knowing now that I need the battery as far forward as possible I can work out fixings for it. 

 

1. First job was to level the tailplane seat, even if it was level it would need sanding flat as the angled in fuselage sides also angle the longerons that the tailplane sit on.

 

 

 

2. Using my new fine Permagrit file as a straight edge, my worry with these tools is that they are heavier than wooden (balsa) sanding blocks and can dent structure when they are dropped (which I do all the time!!). I will use it more for ply formers etc that can be shaped in a vice.

 

 

3. Checking with the tailplane.

 

 

4. To carve the block fairing I needed to fit a dummy tailplane (8 mm thick), I would usually use sheet but 8 mm is an odd size that I don't have so I used some strip wood. Tacked on with a single spot of CA at the front and rear only. 

 

 

5. Tacking the balsa block on, again just enough CA to hold it and not too much that removing is difficult.

 

 

6. Razor planing fun, all strokes from front to rear to avoid damaging the engine pylons. I'm using an old towel to work on as the fuselage is picking up dents etc.

 

 

7.  I used the plastic tail cone as a template.

 

 

8. Almost there.

 

 

9. Separated the parts with a razor blade.

 

 

10. Checking with the tailplane, strictly the block (and fuselage) are slightly short, the block should extend to the elevator hinge line. I can either extend it or just cut slightly larger sections out of the tail cone where it straddles the elevator joiner.

 

 

11. Weighing and CG check with the battery.

 

[Gary Binnie]

This afternoon I sorted the battery fixings, very definitely making it up as I went along!

 

The front fuselage could easily be redesigned at the building stage and a very slightly larger battery would need no noseweight.

 

Tomorrow I might go out flying or fix the nose on and turn the canopy into a hatch.

 

1. First job was to add a front stop of hard balsa, reinforcing the Liteply former at the same time.

 

 

2. Gluing in.

 

 

 

3. Cut off the front of both lower rails as they were slightly stopping the battery lying horizontal.

 

 

4, 5 and 6. Added a Liteply Velcro strap mount across the fuselage and under the longerons.

 

 

 

 

 

7 and 8. Felt that a second strap was needed so cut off the forward ends of the upper rails and threaded a strap under the lower rails.

 

 

 

9. Last problem to tackle was how to stop the battery sliding rearwards, the straps might have held it but I needed something more positive. Discovered that 1/2" balsa was a tight sliding fit between the rails and the fuselage side so I fashioned a piece to do the job.

 

 

 

10. I initially cut it level with the top of the receiver but that fouled the canopy.

 

 

11. Cut it flush with the top of the fuselage side but that left nothing to grip to remove it. Scratched my head for a bit then saw the answer hanging on a nail, a 2.4 bind plug! Made a hole and glued it in with plenty of CA.

 

[john stones 1 - Moderator]

Looking good Gary.

[Gary Binnie]

Cheers, I feel like I'm 'over the hump' with it, the fuselage sheeting was a challenge.

 

Still a way to go.

 

I'm looking at a plan build glider, putting a materials list together and saving up for it!!

[GrumpyGnome]

Lots of good quality work there Gary. Coming along nicely.

GG

[Gary Binnie]

A short post today because I only spent about 15 minutes in the shed!

 

I was going to glue the nose on but that would have been a mistake, I need to see where the front of the canopy sits then line the nose up with it.

 

Noticed that despite not cutting the canopy down to the mould lines that there was a step between the rear of it and the front of the fuselage sheeting. If I had sanded the sheet down to match it would have left it too thin so the other plan was to raise the canopy slightly by adding 1/16" strip to the fuselage sides.

 

1. The step.

 

 

2. Checking the strip.

 

 

3. Went mad and used pins to hold it while the glue dries. Looks slightly rough at the moment but the whole front end has to be sanded, the canopy is narrower than the top of the fuselage.

 

[David Ashby - Moderator]

Looking like an A-10 Garry, and it's certainly keeping you out of mischief ?

[Gary Binnie]

It certainly is keeping me out of mischief!

 

I want to build something else but mustn't rush or abandon it. I've got a few unfinished 'projects' in the loft!

[Gary Binnie]

Lunchtime update:

 

Been 'designing' the canopy hatch arrangement.

 

Added a ply former at the front and tried a single dowel peg locator but the Liteply former of the nose cone crumbled.

 

Next idea was to add a ply tongue to the former and file a slot in the nose cone former, this seems to be working!

 

Have now committed to glue for the nose cone after a lot of adjustment, sanding and tweaking.

 

The lower fuselage sheeting is going to end up quite thin but there is a thick plastic blister fitted in this area, I saw it on the plan but couldn't work out what it was for as it is non-scale (fits just behind the cannon).  I eventually clicked that it's a landing skid along with the half main wheels that are glued to the wing nacelles. 

 

1 and 2. The new ply canopy former with tongue and a squared off recess in the original nose cone former.

 

 

 

3. Final checking before gluing.

 

 

4. Committed to glue. I trimmed some material off the rear so that I can shim it to close up the small gap visible here.

 

 

5. Part 68 is the mystery plastic blister, designed to protect the nose on landing the hand launch version.

 

[Gary Binnie]

Pretty much finished the canopy/hatch.

 

The fuselage sheeting has become very thin and almost broken through after sanding, looking at the cross section on the plan there is very little margin for error.

 

Will probably tackle the engine nacelles next then I will have to think about covering.

 

1. The moulding is quite thin and flimsy so it needed a rudimentary frame, added a ply crossbrace in a position that didn't foul anything though the 2.4 aerials had to be moved.

 

 

2 and 3. Also added some balsa strip along the edges.

 

 

 

4 and 5. Last thing to arrange was how to secure the hatch, I have some magnets but can't find them at the moment so I made a small hook out of ply and used a rubber band which pulls the hatch down and forward at the same time.

 

 

 

6. Nose sanded to shape.

 

 

7.  Can see light at the corners, have backed this with some scrap 3/16" balsa.

 

[Gary Binnie]

Ed's note: I wrote this about lunchtime but couldn't have clicked 'submit', all is not lost!!

 

Mid-afternoon glue drying break update:

 

Adjusted the fit of the plastic engine cores and added strip balsa along the edges. By trimming a small amount of wood from the motor mount they could be fitted as they were intended. 

 

Can't do any more on the engine pods until it's covered.

 

Next job was to finish the wing mount, the wing fit had become a little bit tight, just a touch of sanding needed here and there. Cut the forward dowels to length, I had wondered why they were so long, I found the magazine with the review of this model and read that the fins were dowelled on to the tailplanes. I had seen the optional bolt on fin arrangement but the note to use dowels is not obvious, wouldn't have used them for that anyway.

 

The next job will be trimming the plastic centre section to size and sanding the fuselage to match it.

 

Rapidly running out of jobs to do, will have to start thinking about covering and finishing.

 

1 and 2. Removing a small amount of material from the ply mount allowed the engine core pieces to fit nicely.

 

 

 

3. Adding balsa strip along the edges for more gluing area.

 

 

4 and 5. Revisiting the forward wing mount, dowels pushed in with no glue, wing bolted on, former tack glued.

 

 

 

5. Cut the dowels to length, the reason they are in six pieces and not four is because I cut the wrong side of the marked line!! I usually draw diagonal lines on the piece to be cut off but didn't on this. Enough left to do it again.

 

 

6. Bolted the wing on again and added glue.

 

 

 

[Gary Binnie]

Done for today.

 

Trimmed the centre section fairing down to size.

 

Need a good weather day now to work in the garden, sanding all the lumps and bumps.

 

It's very likely to be tissue covered though I'm concerned about puncture resistance of the open structure bays, I have an idea to use Fibafilm under the tissue but I need to do some experiments.

 

1.  Back to the centre section fairing that had only been roughly cut.

 

 

2. Trimmed back and front.

 

 

3. There are very faint cut lines moulded in which were quite accurate.

 

 

4. Almost there.

 

 

5.  A small problemette is that the finger grip holes don't quite line up, may well build the gap up with balsa.

 

 

6. Will also add a small square of balsa where the pencil is pointing to further brace it from being crushed. 

 

 

7. Front view, was quite pleased that I didn't glue the wing to the fuselage!

 

 

8. Rear view, I am very tempted to add a Liteply or balsa former here.

 

 

 

9. Just a small amount of fuselage rounding left to do.

 

 

 

Edited May 5, 2021 by Gary Binnie
Missing word

[john stones 1 - Moderator]

Looking good Gary, yes on the balsa former.