3rd harmonic

Yeah, i know they won't share the current evenly, although 2x devices on the same die at the same temp won't be too bad, yes it is really about redundancy.

Parallel MOSFET's will because the negative temp Coefficient, BJT's with positive temp won't hence the emitter resistors that give some local current feedback.

As generally seen in audio amplifier output stages (and i have repaired MANY!!)...

The VISHAY bolt on devices would be a good option, abit of a heat sink would be needed.

Shottky diodes don't like high reverse voltages, 60V PIV would be nice maybe.

On 17/03/2024 at 1:43 PM, RFguy said:

take a good look at the fuel injection pump current requirements under various condix, they can pull a fair bit, and that you might have BOTH pumps on due to design (or error ?) 

Given that good quality, sealed non liquid electrolyte batteries generally do not have sudden failures, it's probably a good option as a power source.  a strong schottky diode or MOSFET schottky implementation with some sort of current limit would be a simple and reliable option.  A big schottky with say only 20V 30V reverse barrier will be pretty low voltage drop.  maybe something like 12 or 14 gauge wire will serve as a current limit....maybe aim for wire resistance = diode drop under normal conditions, as a starting point. that will be fine as long as the charging system gets up to 14.4 , 14.6V region

Good point regarding the fuel pumps - yes normal fuel pump powered off the normal bus and the reserve pump powered off the ECU bus behind a diode on the small standby battery. I've used these shottky diodes for a caravan 12V system where i wanted isolation from different charging sources, with both diodes in the package in parallel, for a very low forward voltage drop 

VISHAY DUAL 150V 80A DIODE PACKAGE

In an aircraft i'd be looking at 2x packages, for a total of 4x diodes in parallel.

The DA42 accident is really just a lesson in redundancy engineering that could have EASILY been avoided IMO. I'd say they had a partially sulphated, poorly charged battery that collapsed under load when the L/G was retracted, of course a backup ECU battery modification was suggested AFTER the accident.

Whoever came up with the electrical system design obviously didn't have much imagination...

Unfortunately battery voltage post start and alternator current output check ironically will look artificially GOOD with a sulphated battery. As the voltage will come up quickly and the charge current will be low with the inability of the battery to absorb any charge. A load test will quickly show a battery with high internal impedance.

I don't think there's been any official findings on the UL power velocity twin accident ref reg: N106VT??

Yeah, look as good as points based magnetos for the time when they were the best thing available, life has moved on in the last 100 years. Solid state capacitor discharge ignitions are still simple enough, but miles better. Every lawnmower, small engine, motorcycle and of course the Rotax 91x series are a testament to that - even if carby is completely gummed up after years of non use generally you'll still get a spark that doesn't fail.

Having said that the 2hp 60yr old Briggs&Stratton points motor on my cement mixer hasn't failed yet even though it lives outside with a bag over it...

17 hours ago, RFguy said:

Mike I  gather the UL system  has one alternator and one ship battery.  usually the single alternator is doing double duty and I think that's a bad idea, since the engine systems are not isolated from the troubles and switches and breakers and ge-finger trouble of the user....  The only way to really get away from it is a 2nd power source., or perhaps an independent feed from the battery with its own isolation relay (or a 2nd battery only for the UL so that buys you an hour etc, and some switch that you can cut over the Ul to main ship battery- but then you have a single failure point in the cabin maybe....

so, some thought required to escape the single power feed issue. 

The UL systems having its own feed from the battery and own isolation switch etc is probably the simplist. 

I have been thinking about my UL engine and I agree, RF guy this is likely the best approach.  The greatest danger with ECU's that need power for the engine to run is not the alternator failing as you will have some time to find somewhere to land - but a short to ground. I found that out the hard way with a 1980s BMW E30 323 coupe I used to own. Ill advisedly put a standard size battery in rather than the correct DIN66 battery, which wasn't quite as tall. This worked ok for abit until I went over a decent bump and the + battery post shorted out on the bonnet. The car stopped running instantly and I pulled off the road while fumbling for the bonnet released on the passenger side as the battery was fizzing out acid into the engine bay like crazy.

My thought was to have a smaller separate battery that ONLY feeds the ECU and have the isolated from the normal battery with a very heavy duty Schottky diode. Ordinarily the batteries will be charged in parallel, but a short on main bus won't take down the ECU and cause an immediate engine failure.

There is an unofficial weather station on top of the Adelaide biplanes building that is live online, as well as weather CAMS:

https://www.aldingaaviation.com.au/weather-station/

https://www.aldingaaviation.com.au/webcams/

YADG is where I have done most of my flying, in all seasons over some years.

Yes, in short it can be bloody windy on some days.

But there are 4 runways, so normally you can get into the wind or close to it on one.

As mentioned a strong south-easterly can be very rough as it comes over the hills behind and swirls in an eddy down onto the field.

08/26 and 18/36 are pretty short.

36-18 has a broad dip in the middle about where the '20' is on the ERSA map

14-32 Is mostly gravel with not much grass (especially at this time of year) and has trees at the southern end. Some people worry about them, but i actually like slipping in over the top of them.

In the cub or champ (tailwheel) it's generally suggested to use the grass right next to the LEFT hand side of 21 threshold or the RIGHT hand side of 03

Watch out for the circuit directions, plenty of pilots visiting get it WRONG - aside from the obvious danger, this creates ALOT of annoyance with the Adelaide Biplanes instructors who will be on the look out for it whilst doing training flights.

North is ALL LH. SOUTH RH except 14.

To be fair, it is abit confusing just reading about it on paper until you've seen it directly.

I've attached a word doc with pictures i created to visualise it that may be helpful

Autumn is the best time in Adelaide IMO as the weather and winds are generally more moderate, especially April/May cool mornings, before winter hits - that's in contrast to spring which can be very changeable/showery.

Although it's been bloody hot and dry at the moment, some rain would be nice to take the edge off.

The Adelaide biplanes (Martin/Gaylene) people and cafe are really friendly...

YADG circuits all runways.docx

Well done for having the balls to post up something that's wasn't so easy!!

I ended up going solo after a very limited 9h (although some flying 20yrs previous when I was in air cadets at Camden helped alot)

The solo went OK, but the next session of circuits after 1st solo was a shocker and I didn't fly solo again for another hour.

The point is that as your training progresses, hopefully? It's your worst performances that will improve not necessarily your best.

THAT is actually way more important in developing your piloting skill - In other words can you make good choices and still get it down acceptably when the conditions aren't going your way?

Circuits are bloody hard work in summer when it's +30deg. As someone who is reasonably fit in the sports star with a bubble canopy an hour is about all I could handle and would be drenched in sweat and have to down 2l of Powerade afterwards to recover.

Don't let it get you down

Paradoxically EXPERIENCE is what you get AFTER you needed it!?

There's no short circuiting that learning process...

Ah gee that's really sad, what a loss!

68 is barely past retirement age?

Only reading this now having off the forum for a bit!!

Had the pleasure of meeting Ray in the process of buying the Morgan that i'm currently rebuilding.

He struck me as a kind and friendly gentleman good for a chat, but also good at listening too, happy to humor that thoughts and ideas that had with his experience and wisdom.

One of those situations in life where you meet some once and think it would be great to see them again at some point, but alas it will never be..!

There was an article in sports pilot on him not that long ago, will try to find a link to it...

He showed me around the hanger and there was fair load of stuff.

Aircraft in various states, some needing repair others only partially built.

A lot of the original moulds that were use to produce the fiberglass parts for the Morgan sierra kits.

Dealing with all those items will take some effort and of course won't be the first priority of the family in the circumstances.

But if anyone finds out about a clear-out or auction at some point i would be interested in seeing what might be available.

Yeah I think the APEX engines were a high end side show. The Edge performance ROTAX 91x engines are pretty bloody awesome. He does seem to know what he's doing with the performance enhancements and the engine dyno test station ect. His latest 917sti has managed a conservative 200hp, I would definitely go with one if I had a spare +20,000€

Edge performance in Norway have been doing Yamaha APEX 300 (Jet-ski engine) conversions successfully for some years now. The 300hp EPex300 claims to be the most powerful lightest weight aircraft engines and aircraft powered by them really have smashed it in STOL competitions. BUT unfortunately Yamaha only recently discontinued the production of the APEX engines meaning he can't do any more conversions...

Thanks guys that really is SUPER helpful!

Every aircraft is always going to be abit different, as has been noted, but that info will at least give me abit of a guide to work off in doing some calculation to see if the new main L/G position will fall within an acceptable window.

I have been keeping a tally of the weight of steelwork added vs components removed and at this stage i'm in front by about 2kg.

Not withstanding the reduction in drag by not having a nose wheel.

5 hours ago, facthunter said:

The further the wheels are forward of the C of G, the more directionally unstable it will be but you can apply more braking force. Your Plane MUST have the C of G in the Designer's range and not require fuel to keep it there.  Every plane should have it's Basic wt and Index determined and recorded for the flight.  It's the operator's job to load it correctly to keep it in the range allowed and have a method of doing it . Nev

Yes, there is always a compromise with any design choice and accord to this article (https://www.kitplanes.com/design-process-landing-gear-part-6/) the main L/G position on the C140 was perhaps less than optimal??!

Good discussion about CofG in relation to weight and balance, the importance can't be overstated...

Having done some research and reading to inform my thinking - For a tail wheel A/C a tangent from the contact point of the main L/G should make an relatively acute angle to the nominal CofG as per this diagram - other diagrams specify slight different range of angles 12-18 degrees ect

Unfortunately in all the paper records i have from the original build of my machine i can't see any evidence of the aircraft weight and balance having ever been measured/documented and that really isn't wonderful...

As i am led to believe from reading though the RAaus info, measuring the A/C weight and calculating the balance is NOT an optional part of the process of getting a provisional airworthiness certificate granted for a new experimental build.

Did you guys KG and GB do that as part of getting your machines inspected before test flying?

Do you guys happen to know where the Cof G actually is on your A/C for nominal pilot weight say 80kg + full fuel in the front tank and/or minimum fuel?

1 hour ago, graham brown said:

Just to cheer up the Morgan owners and talk up the price here is a picture of mine/me at Cessnock 2018 when I took it to the airshow to Ray’s exhibition. The Sadler Vampire Ray had there got more attention though. Haha

Hope it inspires you Andrew.

https://www.airhistory.net/photo/524759/19-8651

 

VERY NICE  - how many more kts does the chequered flag rudder give you? Morgan owners can also boast that the all flying elevator avoids the pitch down moment in trans sonic flight approaching the sound barrier.

No wing tanks, just the front tank behind the instrument panel.

I looked at the A3 plans again and while they do show details for attaching the T/W, no detail as to the position of the mains.

I have opted just to add steel to the structure to make it happen like the T/W A/C pictured.

Thanks for looking, that is interesting info...

The steel frame section has to be close to the widest point on the fuselage by design in the way it supports the longerons as they are curved under tension, but that could be abit different in relation to the nose or firewall.

The inside of the previously pictured A/C shows the L/G bolts forward of the tube that forms a triangular shaped gusset.

This is where I'm up to with the L/G attachment bracket - the white template is 2x holes on a 120mm spacing that will form the new L/G mounting clamp which is parallel with the A/C centre line. There is no floor or skin at the moment!

8 hours ago, graham brown said:

The plans have the tail wheel version but the steel frame needs turning around which means a fair bit more pulling apart.

 

Hey Graham, do your plans actually specify a main gear location for a T/W configuration? The original plans I have don't have any such indication.

Turning the steel frame section around (which I'd never thought of) would mean the main L/G is only about 70mm in front of the wing spar, which would be abit too far back by my estimation. The T/W A/C pictured above has the gear around 200mm in front of the wing spar or just behind the wing leading edge. This is actually a great unknown I have to admit. I'm going to have a 180mm range of adjustment in 9x 20mm steps for the main L/G position which should hopefully allow something workable. But actual info would be greatly appreciated.

Ab

50 minutes ago, kgwilson said:

I always land on the grass where possible to reduce tyre wear. I keep the stick back till on the seal & aileron in to wind if there is cross wind

definitely good SOP - if not more important in a T/W A/C . I can hear the various instructors voice(s) in my head 'Don't relax the back pressure just because you've touched down!!'

Great description of the landing too - I think I can picture what your saying...

At one point when I was doing lots of circuits learning, I went and sat at the end of the R/W 21 at Aldinga and watched someone else (similarly incompetent) landing the sports star. They, like me were tending to drop it on flat all 3 wheels at once close to the ground, rather than land with the nose higher and on the mains with the stick right back. Externally didn't look nearly as bad as it felt getting the jolt in the seat of your pants, which did make me feel better as the main landing gear flexing seemed to soak up the drop OK and the sporty N/W has an oleo. Evidence would suggest that the Morgan's are possibly less tolerant of that kind of landing style....

36 minutes ago, kgwilson said:

The 30 knots IAS was maintaining altitude. A smidgen slower and it begins to mush losing altitude. Stall with full flaps in landing configuration is 27 knots.

Yeah wow, that's not bad at all!

I had the idea from the start to do a tailwheel conversion, it seems to good a opportunity to pass up!

I met Ray T at Camden to have a chat generally and had a look at a partially built T/W Morgan. The story was that owner is an ag pilot (with boss level TW skills) and it would have a bigger heavier Lycoming engine fitted - Ray thought it would be pretty wild.

The firewall is closer (further back) towards the wing spar to accommodate the longer heavier engine.

Essentially, I'm looking to replicate what I observed in that A/C as a guide.

Yes, dealing with the steel work that everything attaches to is the difficulty, which has made it harder initially to make much headway. Confronting these structural alterations have forced me to think long and hard about how to do it nicely and have it work out.

Lots of good comments, thanks KG and GB. It has been VERY intersesting to hear first hand how they fly.

Other than talking to Ray T, I didn't have much else to go on.

Especially flight in the slow speed end of the envelope.

30kts IAS is pretty slow - is that actually stalled with a significant rate of decent or just maintaining height?

The sports star that I've done some hours in has a pretty powerful and sensitive elevator which may be similar in that regard.

Compared to the cub/champ the sporty is also very responsive/light on the controls generally which is enjoyable.

15 hours ago, FlyBoy1960 said:

The title is wrong, it should be "Morgan Rebuild"  

 

 

Fair point, I agree - I thought for a while and couldn't come up with anything better. Words often escape me.

I couldn't work out how to edit the thread title, if that's even possible - happy for a moderator change it.

Yes, in a sense a rebuild is a bigger deal than just fixing something up the way it was...

1 hour ago, old man emu said:

I think that there is a mod to make the nose wheel assembly less prone to folding.

I'm sure that might help if the plan was to fix/replace the nose wheel. But I'm hoping to side step those issues entirely 😉

Yes, Thanks KG I have had a good read through your blog and also some of the others on the Morgan page, there's a gold mine of info and pics showing how others have resolved the same design in different ways.

Good to hear that you've managed to fly it consistently, after some initial difficulties.

The engine is a UL power 260is (NOT a Jabiru, which the plans suggest)

I have had some correspondence with UL power about sending it back to the factory in Belgium to be overhauled and replacement crankshaft fitted ect

For various reasons, not the least being the paying the $$$$$, I haven't done it yet...

Against what may be considered sensible or advisable, i decided that the buying a repairable wreck of a Morgan Sierra might a challenging and satisfying project!?

As a brief history: The aircraft was built from kit supplied by Morgan Aeroworks and unfortunately after only a couple of flight hours, ended up suffering a loss-of-control on landing accident.
Insurance was claimed for the value of the expected repairs which were substantial and although it wasn't considered a total loss, the salvage value of the wreck was not very high compared to the cost of the original build.

The accident damage mostly confined to the nose of the A/C.
nose wheel folded under and snapped off
damage to the firewall and floor.
Prop strike, prop destroyed.
Engine mount cracked/bent/broken.
Very minor damage to the winglets and wing leading edges right at the tip.

The wreck was sold to a guy who trailered it to Melbourne, where it sat in a storage unit for about a year.
I brought it off him and trailered him back to SA in an epic 2 day road trip.
As pictured on a very large car trailer.

I have chosen not to identify the original builder explicitly, to be fair as i don't know the guy at all.
Of course there may be some sensitivity regarding the accident, i can only imagine it was NOT a particularly enjoyable experience.
In anycase it's really not relevant to restoration going forward.

Thing have progressed abit from here, but just an initial post to start the ball rolling...

Ab

3mm is a pretty small vent tube, I'd be more worried about it getting blocked by dust and/or mud flicked up off the ground than wasps.

But mud wasps are an absolute bugger where I live in the Adelaide Hills.

They blocked up the air inlet on my compressor and so when I turned it on the dirt was sucked in and damaged/broke the spring steel check valve in the cylinder head!

Then last year went to start our generator during a power outage and it would sort of fire but then stall. Didn't take too long to work out the little sods had blocked up the exhaust right down inside the muffler!

We decided to run it without the muffler, running any motor without a muffler is fun for a abit but the novelty quickly wears off...

Took me ages to clean it out flooding it with water from the hose and the long compressed air jet nozzle.

They did the same to my neighbours fire pump muffler with partial blockage and the mud had been baked into hardened ceramic by the heat.

Little vandels!