RFguy

Skippy, I guess the $64 question is, what happens in commercial underground fuel station tanks . Certainly there is effort (and it is indeed required) that the fuel doesnt sit there evaporating/ taking on air/ oxidizing. The answer is apparently - it depends. Good reason if using ULP to source from drums, ideally.

alas, you wont get a plane in < 600kg gross category, that wants to land around 45 kts , feeling like a plane that grosses at 1090kg and wants to land at about 50 kts.

aircraft wing fuel tanks are often large surface area voids ...probably worst case scenario. - tank breathers (which will breath diurnally) and huge surface area to volume ratio. 2 weeks is pretty good.

Hi SKippy. No, I did not forget to mention that- I deliberately did not mention it because according to this industry professional, that is not true. Certainly addition of fresh fuel recovers a % of volatiles by volume, allowing generally easier starts. But it does not recover the aspects of the aged fuel such as oxidized detergents and additives that may leave solution, tank/vessel impurities now in the cocktail that are a bigger problem .

This discussion excludes fuels with ethanol : **** I had a conversation with a 'petroleum scientist' at an oil company yesterday... yes ! To summarize : 1) When considering how old fuel is , volume/area exposure to air is the principal issue 2) Steel Jerry can sealed tight 90% full - good for 2 years with essentially indiscerable change 3) Plastic container- 90% full : 6 months for the better thicker plastics . Plastic is not a perfect seal.... 4) Vented container - faster... 5) if 50% of tank volume is air, reduce the above time numbers by factor of 4 6) Octane increases slightly then flat lines - maybe 1 to 1.5 points- - Yes there is a octane boost perhaps 4 weeks of storage at 90% fuel total volume . then no change. .Volatiles decrease, leaving octane boosting compounds in excess. 7) Vapour pressure (VP) reduces slightly at same rate (4 weeks at 90% tank Vol), then flat lines, however the VP variation is less than the summer/winter VP supply specification so dont worry about it. 8 ) Most premium fuels contain " detergency additives " - " if oxidation processes are in place – non-fuel soluble compounds can form; this may also be more of an issue for carburetted engines – where the fuel jets allow continued evaporation etc. " 9) Loss of volatiles affects cold starting ability- significantly the vapour pressure (depresses vapour pressure) . turns a winter gasoline into a summer gasoline. 10) Fuels may cause dissolution of tank seals, tank liners and so long durations in non -noble tanks may cause 'unwanted compounds' to be added to the cocktail. so- #8 is an issue for forming nasties in fuel jets, and potentially items like fuel filters/gauze open to the air.

It's clear that the flashtube strobes are powerful emitters. And quite efficient. But the reading I did that steady lights requires some dwell time in a sector of the sky to recognise, whereas the pulses light source could grab your attention quickly was an interesting find. It's a good reason to pulse your light source . I need to replace the beacon on the tail of my J230. GA Tail top Flashtube strobes vary between 25 and 50 Joules. both good numbers Consulting FAA guidance and rules : https://www.ecfr.gov/current/title-14/chapter-I/subchapter-C/part-25/subpart-F/subject-group-ECFR0cb7970b9d1fd5f?toc=1 interesting, 400 candela/flash rate (not much) (of red or white required on axis. overlapping colours ot be synchronized. yeah all makes sense. Interesting #2- for a strobe, 400 candela and 1mS duration and 1Hz flash rate and 20 deg beam angle = ~ 500klms say again, we're up in that 1 million lumens department for narrow pulses. Given that the eye can detect infintestimal pulse width- just as long as enough photons get into the collection bucket to trigger. So, mostly its a battle against the daylight, hence the need for a few million peak lumens.

Yes very much so. 15W of light , increased in intensity on axis (fresnel lens in a tail strobe) x2.1 = ~30W of light from a 50 Joule strobe.. approx 30W at 2km = 30 x (1/ 4pi (2000x2000)) = 6e-07 W/m^2 clear sky app. magnitude of say 1.6 (bright). ( about 0.229 of mag 0) in W/m^2 is 6e-09 W/m^2. so the strobe at 6e-07 W/m^2 is considerably brighter than the clear crisp background daytime sky at 2km. there is an absolute ratio there of around 100x there. recall the 50J flashtube is about 10,000,000 lumens in a sphere , about 21 million on narrow lens axis.... So an LED to do the a tenth of the same job (but likely still visible) needs at least a 2 million lumens on the subject. If the LED is 20,000 lumens (I made a bike flasher that bright). over a 30 degree cone, that's a gain of 58 over a spherical illumination, that's an on axis intensity of 20,000 x 58 = 1.1 million lm- ...... A 3000 lm LED bike light over 30 deg cone will only get you to half a million lumens.

working more on point sots of light and how the eye perceives such things.... the calcs above I did not do my spherical calcs correctly. (doing over breakfast cereal) actual output of the strobe at 1km was 0.8lux, and after the tail top strobe fresnel lens, improved to 1.7 lux clear sky brightness is 1.5 to 4 magnitudes per square arc second. venus close is -4.5 mag and half face illuminated of the 29 arc seconds of diameter is 330 sq. arc seconds which is surface brightness of -4.5mag + 2.5log(330)=1.8. ah ha. visible ! OK my math corroborates with : https://iopscience.iop.org/article/10.1086/430212/pdf and https://vanderbei.princeton.edu/SUTU/2010Oct20.shtml at 2km distant, the tumbler sized strobe is a truly a point source as far as the eye is concerned- only 10 arc seconds in diameter lets call it 157sq arc seconds. maybe go back to working in W/m^2. apparent mag zero is 2.5e-08 W/m^2

Good strobes are 50 Joule flashtube pulses and about 1mS pulse. smaller ones are 25Joules a xenon flashtube converts about 30% of that energy into the visible light range. pretty good. light output of 50*0.3 = 15J . 0.001 = 15,000W . which is... what.. x683 = 10,245,000 lumens., so if an isotropic radiator (uniform illumination of a sphere) 1km away would be 10 lux. wow. quite a bit. now, most of these have fresnel lens reducing the beam angle by 3x, but efficiency of the lens maybe 70%, so on axis maybe 10lux*.7 * 3 =21lux. ....dont trust all my numbers here, they're my first dig at this over a cereal bowl ..... Now, as 15min after sunset could be somewhere around 3 lux sky brightness, I tend to generally believe those 21 lux numbers I came up with , since those strobes are fairly good after the sun dips. not sure I have my conversion of venus apparent mag of -4.5 to lux and background sky correct (earlier post either) . Venus is visible in the day, in very clear atmosphere at closest approach, at ap-mag of -4.5 ish. I am going to have to do some research. Yes magnitude per arc-second of sky is what I need to work on..... more later

And for very low point light differences , for a continuous light source, there is something like 2.5 seconds perception delay, so you need to stare at that bit of sky, a glance will not do it. Pulse light sources are treated differently. more complex relationships with pulse length, intensity etc Probably well described in some FAA publication somewhere

Let us run some numbers Sky background on a clear day with sun at Zenith is about mag -23, which equates to about 3400 lux That's the minimum I reckon. Let's assume you have a 10W LED about 90lm/watt, (=900lm) over a 10 deg cone- At 1m away, that's what...78 square degrees, out of 41253 =which at 900 lm source will be... 472,000lux (lm/sqM) . now 1km away, will be 1000x1000 less or 0.472 lux. gee we're a long way short at 1km at noon..... Now the 737 landing light I read GE Lighting Q4559X https://www.gecurrent.com/catalog/par64-halogen-lamp-42552 They are specified at around 8,000,000 lux !. 1km away they'll be 8 lux. hmm quite a bit ! 15min after sunset, clear sky is ABOUT 3 lux - so yes you can see a 737 at 1km away . Venus is about mag-4, that's a good one to to compare to , that is visible at dusk and dawn.... that is only 86microLux. so the background dusk sky is at least darker than that. I'll think about those numbers, wonder i I have got my numbers wrong.

yeah, they do, but ..then what are you looking out for : an aircraft with no landing light AND no radio comms ? the two probably go together so I dont think you've improved safety by much... But I agree, a really bright landing light will be more visible than nothing-

Try just the capacitors first use lead length on the capacitors of about 0.1" to 0.4" : for the 1uF and 0.1uF, and use 0.1" lead length for the 0.01uF . https://www.minikits.com.au/components/passive/capacitors/ceramic-capacitors/MLCC-Series 1uF X7R 50V 5mm MON105-X7R-50B 100nF X7R 50v 5mm MON104-X7R-50B 10nF XR7 50v 5mm MON103-X7R-50B ferrite toroid : x2 https://www.minikits.com.au/FT82-43?search=ferrite 43 FT82

needs suppression components fitted at the LEDs 1uF in parallel with 0.1uF in parallel with 0.010uF ceramic disc capacitors THEN 3 turns of the wiring through a type 43 ferrite choke toroid or 10 x 1/2" beads

now now

Hi Ian I'll be looking at a processor that uses less than 1W. Most likely a medium 100,000 logic cell FPGA with soft processor, using FPGA fabric as hard matrix solvers. Done that before- familiar territory for me....

Hi Ian It's currently written in a mix of python and C++. It will need to be all C++ to go into an embedded platform. Computationally- fairly intensive as there are alot of matricies to solve regularly, but they're only 4x4s mostly. I'll figure out the computational requirements down the track (no pun intended) Fortunately it only has to calculate everything every second for each update that arrives. And it can sensibly load shed basied on separation if it needs to. I'm not sure right now what the embodiment will be. I am thinking the standalone box with outputs for warning indicators, intercom audio , a large say 24x1 display. Ive also experimented with a 3d looking 2D display plotting points on the surface of a sphere that has your airplane in the centre. . It's possible it could be integrated by 3rd parties into existing applications on tablets. those things have plenty of transient processor power available. I'll do a bit more on this in December when I get a bit more time . MarkD- it could be a box with just inducator out, audio out, RF in ---that also has an output to talk to a MGL, EFIS etc. IE the black box does the computational hard work, leaving another box to display I presume its possible to put messages onto an MGL screen over everything else /.

I dont agree about ADSB being turned off in circuit. circuits can be busy. and radio comms can be crap. but it needs to be in a a mode that adds something to the already busy pilot.

There's acceleration as a vector, and that is allows you to make a turn of course. no acceleration = straight line flight.

Hi Nev no, wouldnt be advising another plane. I'm still in favour of not providing any sugegstions, just information, but Thruster is right that when it gets close, you need somethign like "execute decending left turn"... if the prediction model is doing its job, this info will come fairly early.... the problems come when say you are goinging on base (why?) and someone has not yet turned base, but is late downwind. the predictor thinks (without extra information which it could learn....) that you are continuing downwind. Only when you start the turn that the predictal will go ah oh when it plots your new likely trajectory. IE once the yaw rate ... The predictor is not specifically working from XYZ, its working from calculated yaw, pitch, roll rates (since they are good ways to describe aircraft motion) and velocity that is guesses from the XYZ data.

OME - essentially- how it works - 1) Acquire time series location data (from ADSB receiver from other aircraft) 2) apply a Kalman filter to that data to get the most likely values- since the raw location data from the ADSB probably has a random magnitude of 5m in XY and 10m in Z. 3) Now we have cleaned data, apply the data to a non linear regression prediction tool . There are many- and quite sophisticated tools and algorthms. 4) predictions are done, paths drawn in 3d space, and for each combination of airplanes, distances calculated as a time series to provide a probability of a conflict Think of the use of a Kalman filter as a zero lag averaging tool.

Time to intercept is certainly the pointy end of the stick. I know we all learn see & avoid but we all know it is pure luck if, in circuit, you see another aircraft against say, the backdrop of a town, and that's if you are looking in a region. At cowra downwind for 33 you are looking into the town for conflicts on straight in and other odd joiners. EVen worse where there is NIL wind and everyone has got their own runway direction preference...... I hate that.

OME yes indeed. you'd expect 55-100 kts in circuit for most GA. ... and you only get one KNOWN update per second (although you can generate predictive data at any rate) There's alot that can be nutted out . IE time based / conflict likelihood based etc hybrid. I'll have to read up a bit on TCAS.

Hi OME OK. mmmm. If looking not too far the future, perhaps 10 updates, The Kalman will find recent trend very quickly by itself. It doesnt store past inputs, not like a curve fit--- it is continually generating the most likely next state (state can be X, Y Z location, oir X, Y Z velocity, or X, Y Z acceleration or all of those) . If you really want it to ignore the old stuff, simply rerun the filter from a 'later' time- not including early fixes in the dataset. I'll generate some graphical examples. "Conflict 3 o'clock high distance 400 meters Traffic kilo hotel alpha" is a good start. If thruster88 is coming in from 3 oclock high 400meters away, by the time you comprehend this, he's probably 200m away. I would love to have some sort of 3D 'ball' on the instrument panel that you could see the planes in a sphere around you like little bright dots. I'll get the aircraft going around the circuit in canberra sorted and generate some actual and predicted path maps for you all.

yes. hemisphericals when a few degrees either side of 0 or 180 is always a bit of a game. I heard someone get ' some focus from ATC' in canberra the other day for flying NW at 5500 in CTA when they were cleared to 4500.....