RFguy

Thanks for the encouragement. Yeah I am beginning a new chapter in life really. Particularly socially - a different bunch of people. Electronics hobby as a kid turned into work... Now work and hobby are too close, after so many years I need a change. The very unforgiving nature of flying together with the detail , and meeting new like minded people is the attraction. And flying to get around is handy- --what triggered this- flying around with my mate in his Cirrus regularly was enjoyable . which he is no longer doing as of last month. Its funny when he was practising IFR approaches I would have a mental sweat up absorbing and following everything (as if I was also performing the workload also) like a task overload due to not being familiar/practised -- glen

There aren't many flat four car engines if you exclude Subaru. They are much harder than in 4 in lines to work on and early on were very subject to crankshaft breakages, VW, Borgward, Jowett etc. Worked on them all and the firms VW rally car broke a crank about every second rally. Nev

flat 6 vs inline 6 I see has substantially shorter crankshaft , that's got to be good for construction. although same number of bearing journals , or less, I'll have to look.... I am remembering the days of using plasti-gauge to measure bearing clearances. and locking the doors when I was assembling engines.

How thick is the tank wall ? what is the material (precisely) - FRP or made out of the same stuff as the airframe is ?

Need to get one of those level sensors and see how it goes with detecting AVGAS behind the thick tank wall.

It's an easy yes/no solution. (two of them AND logic to deal with sloshing) .

There are many options.

If you can get under the tank, a few mm thick, an ultrasonic level sensor could go there. (bounced off the air/fuel interface). accurate to a few mm.

I would have a level yes/no sensor at 1 hour and the ultrasonic level sensor. A bit like the low fuel light and the fuel gauge in your car.

At training hold your thoughts and respect the instructor. They are skilled at progressing students through flight training.

BlueAd, that is good advice , They have done this before with many different students. I find the best teachers are ones that can adapt/vary a little to suit the student. I'm not at all concerned about the W&B for the training.... We are not going up there with a toolbox of housebricks..... BUT:

Actually the thing I wonder is : will I easily develop the intuition of 3 axis coordination, or will my brain / visual +hand eye acuity just not be up to scratch learning late in my life (49) rather than earlier. I guess I am dazzled by the learning rate of my 5 yo and 7.8 yo , and wonder if humans continued to be able to learn at that rate (at 5 years old) their whole life, what sort of place we'd live in.

Thanks for the Mackay offer ! I have a feeling the aircraft I buy where ever will be a long ferry home. Sort of reminds me of driving my first car I bought home some distance, barely held together learning to drive a manual gear shift for the first time doing it..-GLEN

The J170 really needs a bit more thrust. 80hp is a bit light, 120 is unnecessary. 100 is nice, so 5 cylinders . ha ha. different crankshaft of course.

glen

Hi Bruce

yeah there are a family these sort of devices, many variations, this is just one of them. Need to get one to see if they play OK with gasoline - IE sense it reliably. In numbers they cost about $4 each...

I might be able to find one with continuous sensors. There might be one with say variable output 0 to 10 V etc, or multiple outputs...

What is the height of the fuel in the tank at 20 litres , approx ?

Glen.

I did a bit of reading on balance, vibration modes and forces in reciprocating ICEs........ There are plenty of good advantages for the flat opposed that I read....And flat four is much much more preferable than inline 4cyl. In fact inline 4 cylinder are terrible beasts. 5 cylinder inline is a useful improvement and has some useful characteristics. No wankels. Although some wankels are used for power generators I read driving motors for vehicles

Got it. Last night I did 'a bit of reading' of a few doctorial theses of mechanical engineers looking at torsional vibrations in ICEs (and how it tells quite a story)

More on that later in the "advanced instrumention" thread when I get around to it. -glen

Ken, and that's a good reason. Nev- yeah I presume similar things apply to inline 6s versus inline 4s as flat 6s versus flat 4s WRT balance. I vaguely remember the Mitsubuishi 2.6L inline 4 had some balance weights on a third balance shaft to improve that big pot 4. At 3000 rpm I could balance a 50 cent coin on the top of the rocker cover of my Datsun L26 6 cly motor.... - Glen

OK. They're incredibly useful for any sort of RF electronics that requires trim in situ. like that. Interesting design they have there, also. looks very cost effective to manufacture.

Aussie company ? hard for aussie companies....unless you export hard..... anyway if you need me to find anything for you, can do. sounds like you were pretty resourceful in this case. I'd probably solder in a piece of 1/16" coax !

Thanks Ken. Seems a good start. Ojh the SP500 was the precursor kit to the 120 eh ? There are a few for sale around the place. I'd probably want to put a new Gen4 motor in it. as step1. Maybe. depends what is in it I guess.

J170, a few of those for sale, but seems a little too much like a trainer, not enough thrust with the 2200 for those large wings for XC cruising. Seems people choose J160s partly for that reason.

Or, I could consider non Jabiru. Jab has good doco, manuals are all good, and there is an enormous collective community experience with them. and they are an aussie company. plenty available used.

I'd be prepared to look at others.

Thanks for the info - I didn't know the SW20 existed ! Have used SW23 (about 50% larger) .

......I am deeply aware that I have the capacity to annoy or distract the instructor, and will refrain. grin. Remember... engineering detail is what I do for a living.. When I was 25 I would probably p1ss off the instructor without thinking, but I am a bit older than that now...

cheers

Hi Mark

Looks like an MHF4 connector (1.3mm across the receptacle cylinder..). Ipex originally. but some variation.

Is similar to a U.FL connector (1.8mm width receptacle cylinder) I use alot of U.FL . MHF4 are a bit of a pain. too small. good for like 5 cycles.

I have various cables like this if you need something . be sure to lever up from behind- under the crimp and tilt forwards

J230 is a top aircraft in paper.... (an under loaded J430) .

Technically only the original builder of a 19 registered and built aircraft can modify it as they are the one who "certified the build" to RAaus when they submitted the compliance paper work.. Unless you can convince the original owner to modify it you are stuck.

You can not learn to fly in it as you did not build it for your own "educational purposes". You have to have all training in a 55, 23 or 24 reg aircraft.

I know.......who is going to know? but these things have a habit of biting you somewhere down the track. I have seen the process when the question arises of unauthorized modification rears its ugly head.

Ken

HI Ken.

Yes that's what I understood from the RAaus technical manual which has great slabs of this in boilerplate.... You have to build it yourself. Thanks for confirming my understanding. There is something about builder / owner variations but this was even more murky. Yes who is going to know....until there is an accident....

I'll end up getting a 24- J120 for starters most likely. affordable and will help me get some feeling for what I really want to do. Seems I cannot get away from having to build a kit, and get tit RAaus authorized and signed off for op in CTA. and 500-1000 hours to build an aircraft I do not have for the stepping stone to modify aircraft for engine instrumentation purposes . "Modify" of course is a variable definition. Spock would not like that.

and as for your steep dive example, I would say the answer to that riddle you have provided it is about relative airflow. The relative airflow over the aircraft would be the same as in level horizontal flight, and the CoG conditions are based on some airflow benchmark (presumably cruise but I have little knowledge of the specifics of aircraft design) , . did I pass?

Hi Yenn,

The 100mm and 1mm example was about using limiting case , in math speak.

My example right at the beginning of this now four page topic- J170D v J230D (which is a lightly loaded J430)

reproduced below :

J170-D Aft Limit 272-mm (10.718”, 27.5%) aft of datum at all weights

Forward Limit :

180-mm (7.09”, 18.2%MAC) aft of datum up to & including 440 kg

255-mm (10.0”, 25.8%MAC) aft of datum at 600kg

and.... 272 - 180 = 92mm, (up to 440kg) then at MTOW 272-255 = 17mm

there are plenty of aircraft similar, this narrow range is not unusual.

You can wrap it in foil but that only works when the shield is wholly encasing the device.

As soon as you connect the USB cable, the radio fields of the outside world comes to the inside 'shielded cavity' , along the outside of the cable... The shield now has a sample of the outside world.

Yes, the wavelength is short and so it acts as a multi wave long antenna, and may be quite efficient.

The shield of the USB cable must be terminated (attached) to the shield (of foil) where it entered the foil shield,

If you need to test this stuff without it getting out, use a fully seam-welded box (or screws on the seams no more than 2.5cm apart .

as for getting a cable into it, run the cable through a piece of narrow (say 10mm ID) metal tube say 300mm long into the box. the tube should be well attached to the box (welded or soldered or otherwise bolted/riveted etc) . soldering it up with brass sheet and brass tube works OK. or copper clad fibreglass PCB and copper/brass tube. or a nice box.

The cable shield should be terminated (attached) to the tube open end.

Glen.

Seems 200 is a good first plane, and 19- ripe for experimental work. (aside from 19- LSA, SK)

Why are all the J200s I can find all 19- ? were they all factory kits ?

Can someone please point me to a POH for the J200, Jab site only lists current stuff.

-glen.

Back to CoG and W&B and competency.

Given that LSAs etc have MTOWs often 2x their dry weight, it would seem that there are a few gaps to be filled in the RAaus PC and GA RPL, IMO. The POH handbook certainly spells it out but there seems to be a disconnect with what is actually being done in the field. I was reading through various silly-bus , and there isn't much discussion on the potential of lost of control aspects of CoG errors.

Overweight but CoG right on the money is one thing, CoG errors leading to instability and LOC is another. Which brings me to another question: If permissible CoG range reduces to an infinitely small range at MTOW , what happens beyond MTOW ? Example, say permissible CoG range 100mm at 500kg, permissible CoG range is 1 mm at 600kg (MTOW), what happens BEYOND MTOW? given that you cannot have negative permissible CoG range. no such concept. But something must happen. does the aircraft begin to need a bigger tailplane to compensate for the fore weight ? and so becomes a bit nose down in behaviour (lowering AoA, lift etc). Given that available lift is coming into this then height (pressure and temperatures) aspects would also become relevant. (but they always were).

a good question for you doyans me thinks.

Glen

thanks all. flying starts mid next week. Cowra. Brumby610. weather permitting. immersion.

I now need a logbook. The flying is about to start.

something not too heavy so it doesnt eat into my MTOW and CoG too much

suggestions please ?

there was this thread but it became about electronic logbooks.

https://www.recreationalflying.com/threads/log-books-pilot-and-aircraft-etc-what-do-you-use.70698/post-508928

glen

Bruce here is a local seller, you want the V25-V version, not the PNP.

https://www.ebay.com.au/itm/AU-Non-Contact-Liquid-Water-Level-Sensor-Induction-Switch-Detector-Y25-V-Y25-PNP/202674325063?

or again,

more here

https://www.ebay.com.au/itm/5-12V-Non-Contact-Liquid-Level-Sensor-Waterproof-Water-Level-Detector-IP65-IP67/313042863663?

use two in an AND setup to deal with sloshing.

How much fluid is that above the tank floor / bottom ? (height) ?

can you get under the tank, for a transducer (affixed, say 5mm thick ) ?

two options come to mind - 1) ultrasonic fluid height sensor (external).

2) reflectance sensor on side of tank, can tell where fluid is above that level, or not. Am doing work with SPO2 sensors right now, perfect. I will order an extra one for you.

Here you go Bruce

http://www.naylampmechatronics.com/img/cms/Datasheets/XKC%20Y25%20T12V.pdf

https://www.ebay.com.au/itm/XKC-Y25-V-Y25PNP-Non-Contact-Liquid-Water-Level-Sensor-Induction-Switch-Detector/192913253604?

I will get a few different types .... use a pair of them each side in a AND style and drive a single bright LED etc.