DooMaw - building a STOL

[Head in the clouds]

December 18th 2017.

 

Once I had some new materials and components to work with, and with 'real' work slowing down as it often does in my industry around year's end, I could get back in earnest onto some of the final assembly work.

 

First I worked on the pedal assemblies. They were more-or-less completed some while ago but there's always some finishing touches to complete, I had to touch up some epoxy paint, fit the toe-brake pedals, and now that I had them I could fit the four new master cylinders which will provide both seats with full independent braking.

 

That all worked out fine so I was able to bolt the pedal assemblies to the floor panels and final-fix the floor panels down. Lastly I made the thin aluminium plates each side of the pedals, on which the pedals sliders run when adjusting the pedal positions, so that they don't scuff the floor timber. Gave them a bit of polish for a better appearance and was able to move on.

 

Some pics -

 

 

13 more hours for the log - making 1800hrs so far.

 

 

 

 

 

 

[Head in the clouds]

Next I needed to get the under-seat impact foam cushion made, so that I could complete the seat itself, because the seat had to be in before the joystick and aileron torque-tube could go in.

 

I sourced the impact-absorbing foam from my favourite foam suppliers, PJ Bowers in Reedy Creek. I don't think you'll ever find a more helpful fella than Steve, one of the partners there. They had some large bags of off-cuts from a theme-park protective crash-barrier. It is 12mm closed-cell polyethylene, multi laminated, and came in pieces about 120mm thick. Being closed-cell it won't absorb moisture and therefore is rot, mildew, and mold proof.

 

I cut up the sections of it with an electric carving knife, glued them all together with an industrial strength instant grab spray contact adhesive and then carved out channels and pockets on the underside for the four rudder cables, clearance for the throttle torque-tube and throttle levers each side, the throttle friction device and the harness attachments.

 

Then I could finalise the position of the lacings that would secure the seat fabric and make cutouts in the timber floor under the seat to accommodate the lacing, varnish the timber where it was cut and final-fit the floor in place with its screws.

 

Once that was in the throttle torque-tube was fitted and the three central joining bolts were torqued, then the throttle cable fitted to the left-side throttle lever, and those bolts also torqued.

 

Finally I fitted the throttle friction and torqued those bolts also.

 

Once they were in I fitted the seat and laced it up tightly so that I could determine exactly where the harness straps needed to come through at the middle attachment and marked it for modification in the industrial sewing machine.

 

Some pictures -

 

 

Another 14hrs in that lot, 1814hrs in total so far.

 

 

 

 

 

 

 

 

 

 

 

[Blueadventures]

Next I needed to get the under-seat impact foam cushion made, so that I could complete the seat itself, because the seat had to be in before the joystick and aileron torque-tube could go in.I sourced the impact-absorbing foam from my favourite foam suppliers, PJ Bowers in Reedy Creek. I don't think you'll ever find a more helpful fella than Steve, one of the partners there. They had some large bags of off-cuts from a theme-park protective crash-barrier. It is 12mm closed-cell polyethylene, multi laminated, and came in pieces about 120mm thick. Being closed-cell it won't absorb moisture and therefore is rot, mildew, and mold proof.

 

I cut up the sections of it with an electric carving knife, glued them all together with an industrial strength instant grab spray contact adhesive and then carved out channels and pockets on the underside for the four rudder cables, clearance for the throttle torque-tube and throttle levers each side, the throttle friction device and the harness attachments.

 

Then I could finalise the position of the lacings that would secure the seat fabric and make cutouts in the timber floor under the seat to accommodate the lacing, varnish the timber where it was cut and final-fit the floor in place with its screws.

 

Once that was in the throttle torque-tube was fitted and the three central joining bolts were torqued, then the throttle cable fitted to the left-side throttle lever, and those bolts also torqued.

 

Finally I fitted the throttle friction and torqued those bolts also.

 

Once they were in I fitted the seat and laced it up tightly so that I could determine exactly where the harness straps needed to come through at the middle attachment and marked it for modification in the industrial sewing machine.

 

Some pictures -

 

[ATTACH]53379[/ATTACH] [ATTACH]53380[/ATTACH] [ATTACH]53381[/ATTACH] [ATTACH]53382[/ATTACH] [ATTACH]53383[/ATTACH] [ATTACH]53384[/ATTACH] [ATTACH]53385[/ATTACH] [ATTACH]53386[/ATTACH] [ATTACH]53387[/ATTACH] [ATTACH]53389[/ATTACH]

 

Another 14hrs in that lot, 1814hrs in total so far.

Enjoyed the update; nice work and your getting closer to that 90% done marker / milestone. Cheers Mike

 

 

[Head in the clouds]

I marked the seat for a hole to be cut out for the harness straps and then undid all the lacing again to remove the seat and sew in a reinforcing patch around the hole. That done it was all laced back in again at the front only, the steel cable that the harnesses attach to at the centre was made up, swaged and fitted and the harnesses threaded through the seat and bolted to the cable in the centre, and to the cleats at the outside edges of each seat.

 

Next the aileron torque-tube which carries the joystick had to be threaded through the hole in the seat and threaded through the triangle formed by three tubes which supports the rear bearing for the torque-tube. It was a bit like trying to work out a chinese puzzle for the first time, so I was mildly relieved when I did find a way to actually thread it. For a few moments I was beginning to think I may have painted myself into a corner.

 

Next, and equally tricky, was fitting the split bushing itself, I had to machine some extra clearance to get a spanner on the nuts underneath, and modify a spanner for the purpose but got there eventually. I also made some extra 0.005" shims to go between the two halves of the bushing, and applied plenty of graphite because it was just a little too tight.

 

That done I was able to fit the forward torque-tube support bearing, also with shims and graphite powder for lubrication, the bolts on both t-t bearings are fitted 'snug' (not torqued) with nyloc nuts/washers etc, so as not to crush the plastic bushing material.

 

Once the torque-tube was fitted I could install the joystick between the pair of bellcrank bearings that carry it, and fit the first of the elevator pushrods that runs down the centre of the torque-tube.

 

Some pictures -

 

 

Another 10hrs, 1824hrs so far.

 

 

 

 

[Head in the clouds]

Enjoyed the update; nice work and your getting closer to that 90% done marker / milestone. Cheers Mike

As in ... 90% done, 90% still to go?

 

>

 

>

 

With the first of the elevator pushrods in place I went to the rear of the fuselage and clamped the elevator control horn in the central position, then I could determine the exact length to adjust the rear elevator pushrod (there are four elevator pushrods in the length of the system). That rear pushrod needed to be the exact length that would make the control horn contact the control stop at the same time as the bellcrank on the other end of it is at right angles to the pushrod, since there is no differential in the elevator motion i.e. the up and down angle is the same. Once that length was determined I removed the rod-ends and nuts, cleaned the threads and applied Loctite 243 before re-assembling and tightening them, being careful to end up with both rod-ends in alignment with each other.

 

I re-installed that particular pushrod with temporary nuts on the clevises because they will have to come off again for the fabric covering, and moved on to the next pushrod. Similarly its length had to be adjusted so that it was at right-angles to the bellcrank and also at right angles to the walking beam halfway down the fuselage. Then remove it, disassemble, clean, loctite, re-assemble etc. A word of caution for any future owner who might use this log as a manual when servicing the aircraft, it would be easy to damage the aft end of that particular pushrod if that end is not supported upwards because it could jam in the diagonal internal bracing, so when removing or replacing it, the aft end of that pushrod should always be unbolted from the clevis last and bolted onto it first.

 

Next I adjusted, removed, cleaned, loctited and replaced the third pushrod, the one in the forward part of the rear fuselage and which attaches between two walking beams.

 

Once those three pushrods were set to their final lengths I clamped the joystick in the centre of its travel and could then adjust the length of the forward-most pushrod, the one inside the torque-tube. Then disassemble, clean, loctite, re-assemble etc.

 

Important Note about this front pushrod - when the joystick moves from side to side in an arc of approximately 50° the forward elevator pushrod must 'twist' by that same amount. This MUST NOT result in any movement of the rod-end threads, or any twisting load on the pushrod. It is achieved within the lateral rotation of both of the balls in the rod-ends. They can only provide that motion if small spacers are provided each side of the balls, within the clevises AND the rod-ends must be well aligned with each other (± 2°). Those spacers (4of) are made from 5/16" tubing bored 1/4" and they are 1.9mm/0.075" ± 5% long. Installed with very small long-nosed pliers.

 

The pictures show the small spacers installed each side of the pushrod which rotates (note they're only on the first pushrod's rod-ends, not the other three pushrods which don't rotate), and how they allow the rod-ends to rotate further than they could if the clevis was only as wide as the rodend, without the spacers -

 

 

9 more hours for the log, 1833 hrs so far.

 

 

 

 

 

 

[Head in the clouds]

With the aileron torque-tube installed I could concentrate on getting the aileron controls made up.

 

I will need another eight 5/8"x0.049" 6061T6 pushrods in all. Two behind the seat, connecting the torque-tube to the overhead bellcranks, two from those bellcranks to the torque-tube stubs in the cabin roof, a pair in each wing to operate the flaps and a pair in each wing to operate the aileron control surfaces.

 

So I machined up 16 pushrod ends to accommodate the ball rod-ends.

 

Next I drilled the bellcrank plates which I made up about a year ago and spent time with the little shop-press to shape them. One arm of each is bent outward a little, to the width of a rod-end, the other arm is bent out further because it will accommodate spacers similar to those described in the previous post, but this time it's to allow the pushrods to depart at an angle, rather than to twist. The same basic concept though, to provide increased clearance between the cheeks of the rod-end and the clevis.

 

I put some temporary rivets in the bellcrank plates and their bearings, they'll need to come apart again for painting, which I'll do at the same time as all the other components being made up at the moment for aileron and flap controls.

 

Once I had the bellcranks in place and at right angles to the line of the pushrods I could measure the required pushrod length and make them up.

 

The pictures show the machined pushrod and bellcrank hardware and the trial-fitting of the pair of pushrods between the control torque-tube and the bellcranks at the top of the cabin -

 

 

Another 11hrs for the log, 1844hrs so far.

 

 

 

 

 

 

[Head in the clouds]

Before I could go any further with the aileron controls I had to know the exact position where the aileron torque tubes will disconnect for the wing-folding mechanism. That point will be in a direct line with the pivot point for the wing dihedral and that is determined by the compound articulated joint where the rear spar connects to the fuselage, which is the only point where the wing remains connected to the fuselage when it folds, apart from the strut connections of course.

 

So - the next task was to get back to the CAD work and design the rear spar wing root fitting. That took a day and a half but once I'd worked it out I felt ready for a bit of machining again, so decided to go ahead and make them. Part of the reason for making them straight away is that it was pretty tricky to get my head around what moves when and where, as the wing folds and rotates, so I wanted to be sure it would work and end up as it should. Remember that these wings don't just fold back, they also rotate and fold flat against the fuselage sides.

 

Anyway, I started machining last Friday morning and finished on Monday afternoon. They probably don't look much for 29 hours of machining but there are a lot of processes involved to machine them manually. Or perhaps I'm just getting slower in old age ...

 

They went together just fine which was pleasing and seemed well, but as I fiddled with them I realised that at the last part of the wing-folding action the inner and outer parts wanted to over-centre around each other. At first I thought that would be a good thing as they would 'park' positively with the spar root fitting under the fuselage attachment. But ... the 'collapsing' action as they over-centred would position the end of the wing lower skin beyond the fuselage fitting requiring an ugly cut-out in the skin or a cover plate, neither of which I fancied.

 

So - the answer would be to make up a new pair of the central links and round off one end of each but leave the other end square so that it would only have limited movement, how much movement it actually needs can be determined later and the square end adjusted to suit. Consequently I spent most of Tuesday making the replacement links.

 

More 'real work' starting tomorrow so I guess things on the plane will slow down a little, for a while.

 

The picture shows the articulated rear spar wing root fittings, which, in combination with the top and bottom articulated strut end fittings that I machined this time last year, allow the wings to quickly and easily fold flat against the fuselage sides -

 

 

36hrs for the build log, a total of 1880hrs so far.

 

 

[ClintonB]

HITC, I am only asking because my LAME who is helping with the Bushbaby rebuild got real jumpy when I suggested using graphite as a lube. Is graphite ok for use on 4130. He had explained that graphite works it way into the metal at a molecular level and can cause strength problems. I was going to use it on the same type of nylon block control mounts where mine go cross ways for dual sticks, They were binding and I ended up with 0.005" plastic shim material and grease in the end which freed up the controls perfectly.

 

cheers

 

clint

 

 

[Head in the clouds]

HITC, I am only asking because my LAME who is helping with the Bushbaby rebuild got real jumpy when I suggested using graphite as a lube. Is graphite ok for use on 4130. He had explained that graphite works it way into the metal at a molecular level and can cause strength problems. I was going to use it on the same type of nylon block control mounts where mine go cross ways for dual sticks, They were binding and I ended up with 0.005" plastic shim material and grease in the end which freed up the controls perfectly.cheers

clint

Hmm, good point, I think it's only a problem with aluminium as far as I know.

 

In any case my control torque tube is well painted with primer and then 2 coats of 2 pack epoxy so unless all that wore through, which I don't imagine it would, then there wouldn't be an issue.

 

I will check though, it's easy enough to clean it off and replace with another type of dry lubricant. I wouldn't want to use grease because it picks up dirt and would probably make the condition worse than without any lubricant at all. AND - the plastic absorbs anything liquid and swells, making the fit tighter again.

 

Either way, the torque tube isn't really loaded up much at all so I can't imagine any slight weakening being a problem, but best to err on the side of caution.

 

Thanks for the heads-up, I'll look into it.

 

 

[Head in the clouds]

Not really anything to do with the DooMaw build, but it's my thread so what the hell ...

 

As some of you may have noticed I've had an enforced break from the build for the last six months, I just have so many other things going on. All very pleasant and adventurous things - travelling, sailing, powerboating, exploring, fishing, but not leaving enough time to get stuck into the build. All that will change soon and DooMaw will be the focus of attention again.

 

However - I've been getting a bit concerned at how little time I've spent in the air the last few years and, of course, when DooMaw is finished - hopefully in about twelve months - I'll have the test-flying to do, and I have been wondering just how rusty my handling skills might have become. For a while I've been thinking that I really ought to try and find a cheap plane to be able to get very current again, not to mention that I really miss regular flying.

 

I'm fortunate that I often seem to have good luck on my side - I idled away all of about half an hour looking at classified ads in Sport Pilot, ebay and Gumtree, and came across half a dozen possible projects and a couple of planes that didn't need much work at all but were probably a bit more than I wanted to spend at this stage, with several large expenses still to go on the DooMaw project.

 

I went and had a look at most of the 'projects' and after pricing up replacement parts and new skins (Thruster TST types) it just wasn't going to be worth resurrecting them. Then there was/is a Saphire in virtually original condition with spare engines for just $7000 which was extremely tempting. The Saphire is a lovely plane to fly, I flew quite a number of hours in them in the '80s - but it just wasn't quite what I was after this time. I wanted something I could land off the airfields, and the Saphire would also be a problem finding hangarage as it didn't have a trailer.

 

Then I came across one of my very favourite ultralights for sale, complete with its own trailer, and an owner with a very specific requirement in terms of the new owner, who would need to have lots of ultralight and taildragger time, both of which I have.

 

To cut the story a bit shorter, I am now the proud owner of the last-built Lea Kestrel, which Cec Lea built as his own aircraft, so it has a fair bit that the earlier ones didn't, in particular being fully enclosed but can be flown with doors off, and Stitts/Ceconite covered wings and tail which are much cleaner than the dacron ones (better performance) and don't have to be replaced regularly either.

 

It has very low engine and airframe hours but hadn't had a Periodic/Annual Inspection for a couple of years (although the engine was run, and logged, every fortnight). So I got my head into study mode and completed the L1 course and exam in a couple of days and got stuck into the servicing and developing new logbooks. I also got into the study for the RAAus Weight and Balance course which takes quite a while, there's a lot to read, did that exam as well - and failed. It was the first exam I've ever failed and I was particularly annoyed that they won't tell you which questions you got wrong. The pass mark is 90% and there are 23 questions with no time limit, but it means you can only fail two questions, I failed three. It took me four days to do the study and then 2.5hrs for the exam, so I wasn't happy.

 

I re-read some of the course and took the exam again a few days later and passed but I still got two wrong.

 

That meant I am an 'accredited weigher' so I could do the weighing and W&B loading schedule for the Kestrel. I'm glad I did, there were some considerable errors in the original one.

 

So far I've only had time for one quick flight and I'm very happy with the performance and handling - more about that next time, back to work for me now and here are a couple of pics -

 

 

 

 

[Soleair]

Congrats on both your new plane & your certified status. I'm sure you'll have so much fun now you'll have to discipline build time back in to your day!

 

Bruce

 

 

[ClintonB]

Great inspiration to get stuck back into the Bushbaby repairs. Flying is far more fun than looking at it in the shed.

 

Kestrel looks great.

 

 

[Head in the clouds]

Great inspiration to get stuck back into the Bushbaby repairs. Flying is far more fun than looking at it in the shed.Kestrel looks great.

Thanks ClintonB, it's always been my hope that I might occasionally be an inspiration for people with anything aviation related.

 

Sorry to hear about the Bushbaby, I didn't know you had one damaged. If there's anything we can do to help, feel free to ask ...

 

 

[Kyle Communications]

Congrats on your pickup. I met Cec a long time ago and found him to be a really nice guy. Back in my model aircraft days. A few of the modelling guys had Kestrals and some wierd and wacky looking other minimal ultralights in those early days. Barry Evans sold his a couple of years ago and I think Rob Perdunas still has one and its on floats now. I saw a couple of videos recently of him flying it around Bribie Island

 

They seemed to be a very popular aircraft

 

 

[Head in the clouds]

Congrats on your pickup. I met Cec a long time ago and found him to be a really nice guy. Back in my model aircraft days. A few of the modelling guys had Kestrals and some wierd and wacky looking other minimal ultralights in those early days. Barry Evans sold his a couple of years ago and I think Rob Perdunas still has one and its on floats now. I saw a couple of videos recently of him flying it around Bribie IslandThey seemed to be a very popular aircraft

Hi Mark, thanks for your kind words. I'm delighted with the find. I've been over every inch of it in the last three weeks while doing the Periodic/Annual and I'm happy with every part of it - and it includes some very innovative and sensible design. I feel that I'm a lucky person in that regard too, because if I find things that I don't like I either have to change them or I won't feel relaxed in the air.

 

The rego changeover came through today from RAAus so all the documentation is in order - fun times ahead.

 

Yes, I saw Rob's float videos yesterday, looks like fun but requires a lot of help for trailering, launch and retrieval - amphib would be nice but too heavy I think. Howe, on this site also has one, and another that he's rebuilding which will be for sale soon if anyone else wants to join the fun.

 

 

[Kyle Communications]

Yes I see Howie from time to time at Ycab...although I havent seen him for a while now since the guys in the hangar next door have pretty much sold all their aircraft. Every sunday morning they would get there and have the usual mens shed meetings :). Howie would show up in his convertable every second or third weekend.

 

I think about half of my model club were flying ultralights at some stage back in the early 80's.. I was away at Kingaroy flying gliders back then. You would probably know most of those guys from those early pioneering days..or should I say free for all days by some of the stories. I still see quite a few of the guys now

 

 

[ClintonB]

Thanks ClintonB, it's always been my hope that I might occasionally be an inspiration for people with anything aviation related.Sorry to hear about the Bushbaby, I didn't know you had one damaged. If there's anything we can do to help, feel free to ask ...

Hi HITC,

It’s probably not broken, just lustful eyes looking when I bought my first airplane not noticing all the faults and deficiencies. There were lots of worn bushes, and horrible little hardware store bolts everywhere, and things like 5 hinges in a row with none on the same angle.

 

With some help it is getting better and safer. Time is the hardest thing to find( plus very cool in the shed this time of year at night).

 

I will have another push at it before the end of year. It has only 270 odd hours on it and I am halfway there on the fixing, only 60% to go as they say.

 

Cheers

 

 

[Head in the clouds]

.... You would probably know most of those guys from those early pioneering days..... I still see quite a few of the guys now

Yes, I would probably know a few of them, and others by reknown - all very fine of course! Sadly many of those I knew have passed on.

 

I actually had my earliest flying years in the south of France and then UK. By the time I was in Australia, in 1980, Australia was leading the world in ultralight and microlight (trike) flying, and was just then overtaking the world in hang-gliding too, courtesy of Mr Moyes ... so it was a great time to continue my aviation interest here.

 

It would be a great idea to have a 're-union' of some of the pioneers and early flyers before we all get too old to remember the stories and/or fall off the perch.

 

How would be go about getting a list together of the 'old-boys' contact details so we can arrange something? It might be good to combine it with a fly-in or something perhaps?

 

 

[Head in the clouds]

Hi HITC,It’s probably not broken, just lustful eyes looking when I bought my first airplane not noticing all the faults and deficiencies. There were lots of worn bushes, and horrible little hardware store bolts everywhere, and things like 5 hinges in a row with none on the same angle.

With some help it is getting better and safer. Time is the hardest thing to find( plus very cool in the shed this time of year at night).

 

I will have another push at it before the end of year. It has only 270 odd hours on it and I am halfway there on the fixing, only 60% to go as they say.

 

Cheers

OK, doesn't sound too bad, but understand where you're coming from. The offer of help stands, if you need it. I have a good selection of 3/16 and 1/4 AN bolts if you need some. All the best.

 

 

[Kyle Communications]

It would be interesting although most of the guys dont fly anymore.... some are quite old now. In the early 80's I was only early 30's myself and most of them were at least 10 to 15 years older than me then. I will ask some of the guys I know if they were interested in a get together somewhere and see what happens.

 

 

[Methusala]

Fly-ins died when the nuts from CASA started to attend and do ramp checks. Someone that I know was hauled over the coals for fitting an un-approved but very much improved tailwheel to his Drifter. We all know that Austflight will not provide spares and that the fabled Robinson bros, who own the type approval for Thrusters are not interested. Ultralighters go about their business quietly and with the great store of practical knowledge accumulated over the years. Happy flying.

 

 

[howe]

Still flying Mark, I think during the week YCAB would have to be one of the most deserted airfields except for those helicopters.

 

They must be nice folk though as they always give me a radio check.

 

 

[Head in the clouds]

.... except for those helicopters.They must be nice folk though as they always give me a radio check.

Well, much as I started in fixed wing and will end my flying days in fixed wing, I'll still have ten times more rotary hours, so I can quite understand what you're saying about willingness for radio checks. To explain it ... we heli-fellas are just grateful for any excuse to have a chat

 

 

[Kyle Communications]

Hi Howe Yes flying at YCAB is dodging the helicoptors lately and on the weekends too. The best flying is midweek certainly. There has been a lot of chaotic flying and people using wrong runways etc on the weekends. I went up with Dan3111 on the forum here a few weeks ago to help setup his BOM on the Ipad and I have to tell you it was dodgem cars out there. Total bedlam we both could not believe how low the standard of piloting was. Probably a discussion for a different thread though.

 

 

[Head in the clouds]

Well, I'm back on the case with DooMaw at last.

 

Some while ago I made the front spar attachment fittings and installed them as well as the rear spar fittings shown in post #255.

 

I'd also started to make the parts for the aileron and flap torque tubes in the cabin roof which provide for the automatic connection and disconnection of those controls when the wings fold. They're the bits that go with the 'dogbones' that some may recall I made from the drilled balls in rodends, described in posts #175 and #176. Coincidentally, that was two years ago today!

 

Last week I made the rest of those parts and welded them onto the ends of the cabin roof torque tubes and cross-drilled the fittings on the other side to bolt them on.

 

I also made the flap control handle and the spring-and-detente mechanism and fitted that to the flap torque tube.

 

Then made up the short pushrods that connect the aileron bellcranks to the aileron torque tubes and fitted the whole lot together.

 

A few small adjustments with shims and it all moves very smoothly and freely without any discernible play or lost motion.

 

Some pics -

 

 

Another 19hrs for the log making a total of 1899hrs so far.