RFguy

On MOGAS / ULP and flying at high altitude. I was thinking about this with my flying at FL115 with ULP for cruise. The big issue is the RVP, (Reid vapour pressure) and the VP. (RVP is at 40 deg C) The RVP for AVGAS varies between 38 to 49 kPa. For Australian BP Premium 98, it is listed as 30 to 100 kPa . Many states mandate maximum average RVP of 67 kPa and some lower- 55 kPa in summer months ( don't store fuel across seasons) . The air pressure at 3000m is 70kPa (stp) and ~62kPa at 4000m. So we are getting into trouble territory for some MOGAS deliveries / tolerances at higher temperatures or high altitudes .. Take the temperature down and things look much better. There are two regions to think about, tank temperatures, which could be high if the aircraft is sitting on the ground all day in the summer, and engine bay temperatures. In the engine bay, temps are high and the VP may be exceeded just because it is hot, requiring that region to be pressurized with the aux fuel pump. - pressurizing to 5psi (~ 71kPa) using the aux fuel pump will in most cases push the pressure above the vapor pressure if the fuel and prevent vapor bubbles forming between the firewall and the engine fuel pump. Beyond the engine fuel pump, that's deemed 5psi (PA28) , also (is it at all flow rates for your aircraft ?) . Which brings me to : To ensure the fuel between the firewall and engine fuel pump stays a liquid. : a) aux fuel pump may be required at altitude where DA > VP . b) aux fuel pump may be required with hot fuel from the wings at any altitude. c) Use of a low RVP fuel (AVGAS or summer MOGAS) may be necessary any time the fuel between the fuel pump and the carb is > 40 deg C. It's not all bad : The VP does reduce substantially as the temperature falls . (see graph below) But- If the ULP is 'winter fuel' the RVP could be up to 100 kPa. Certainly in the USA. Not sure in Australia, but the data sheet does say 55-100kPa in the Australian datasheet. For the winter fuel, the VP at 21deg C is about 71kPa- about fuel pump/ fuel system pressure. Trouble region. At 10 deg C, its down to around 50 kPa. So there lies an issue - a hot engine bay AND winter ULP - the combination is problematic. I would like to have fuel temperature as well as fuel pressure. For low wing aircraft, or high wing with low mounted collector tank it needs to be drawn through long tube, reducing the pressure as the system in that region is in tension. Fortunately it is not always hot in these regions of the airframe. That is UNLIKELY to be an issue unless you are taking off from a high altitude airstrip (or in high DA scenario) and have hot fuel in the wings. If the fuel in the wings is at 40 deg C, trouble between the fuel draw and the firewall pump is unlikely to occur at DA of below 3000' . Fuel suction tension in 2m of 1/4" tube at 55 gph is ~ 13kPa. at 30 gph, 4kPa. For 7/16ID @ 55 gph 7kPa... so that will increase the effective DA with the suction component for a low wing. Conclusion- TO, climb and land on AVGAS or other low RVP fuel (summer MOGAS) . Footnote- 100% Ethanol is quite good..... more useful info page 40 onwards https://www.chevron.com/-/media/chevron/operations/documents/aviation-tech-review.pdf

well he doesnt know any more than us.

I dont read anything about that in the ATSB prelim report.

I read that as control surfaces were connected. But may not have been functional after hitting something . maybe pitch up due to damage , since the distance between impact and wreckage was a fair way. gust of wind or engine trouble, or both or excessive load and failure to gain altitude. Something like that even momentary engine stumble might be big trouble. You'd expect a tailwheel pilot to be ready for a gust of wind. My wild speculation, at best . arrogant presumption at worst .

WHat does it mean by : " Flight control continuity was established through several breaks to the flight control surfaces." Does this mean flight controls were intact (IE controls connected to the surfaces ) ?

Fuel return is to permit circulation of : heated fuel (changing its vaporization behaviour) , purge / pass bubbles in the line around the system . So, it does provide a very useful job. For a system without a collector, it does pose some issues to which wing you might put it back into. high wing with collector tank for both wings - fuel return is easy. Rotax requires that a fuel return is provided for in its installations . (past 6 years) . Skip, so 5 litres / hour now ? IE something about a bit above idle for that engine . or about 4 tablespoons per minute. , amounts to a velocity in the delivery of (2 x 5 lph) of 2.7mL/second. for 1/4" ID (VOL = 31.6mL/meter ), the fluid is 'changed out' abotu once every 11 seconds. sounds reasonable. I think you could go half that again and still have plenty of return .

golly.

NOTE - this engine and the chinese bits were discussed elsewhere in this webiste/ forum.

In my case of having traffic to my right , turning right would have meant the collision occurs a few hundred milliseconds earlier. My best option would have been to pull up since. I was below or at Va. Now, if they had ALSO gone right right that would be OK if I had also gone right. if they had gone right down , would have been best for me to go up left.

anyone wondering go to the CASA myCASA portal, log in, go to medical, and there you start the process. you fill in your GP name and details and you get a partially filled in 11 pages to take to your GP that does the same examination as a Heavy Vehicle License test, tick the boxes, fill in a few things. If it is "unconditional" then you just say yeah I am unconditional and the class 2 basic med certificate is generated on the spot and you are done....

so be it , prefer none than delayed or rely on a system that may have high latencies. radio should catch others... mobile data is very low reliability over anywhere serviced by multiple base stations and or base stations that are busy. I will see RPT (they have ADSB without ozrunways) , and many GA. if the others dont have at least a SE2, not much I can do except listen in the radio. down the track I might add a interferometer receiver which can determine likely location of transponder only aircraft by trilateration and triangulation.

I'm convinced reliability is straightforward . just keep the oil clean / fresh, temps moderate, fuel line strainers and filters clean, avoid large changes of throttle < 3 seconds, and for continued monitoring watch the oil filter foreign body contamination and do leakdowns.... simple.

I intentionally prevent my Ozrunways from showing any mobile-data derived traffic due to the lag. I just use the SE2 for my traffic reception on the wifi connection.

probably just a thermal bubble letting go.

I had a bit of a chat to them a couple of years ago. Still unsure whether they made it under license or if it was a pure clone without all the know how. I just cannot beleive they would make it to 700 hours (so far back then) (which people I have independently spoken to in EUrope) if it was an 'uninformed clone' .

correction : my 1000m up and down if shielded should read 1000' . feet not meters.

traffic that is 'OLD" or "out of date " (say 3 seconds) needs to be put into a different colour traffic bubble . I dont like anything with a cellular or third party network that does not deliver time definite in the way....

and baro from the SE2 would have a high uncertainty because it's position could be the subject of variations from atmo pressure.

agreed on nice to see say, inbound traffic 8nm the other side of the airport when inbound, gives you some think time to decide your intentions.

good points on delays. lot sof poor / suboptimal implementations out there there isnt complete blocking by wings at least for close proximity - signals conduct and bend around wings , there is re radiation from the airframe etc. At least up to about 1000m above or below it is going to be pretty bulletproof. It does open you up to the ADSB semi-blocked transmission getting stomped on by another in busy airspace , but that's a low likelihood with 120uS bursts and position being transmitted at ~ 2Hz. My production ADSB-TCAS implementation will be real time. and it is predictive. I have ordered 30 sets of raw data capable GPS modules for my project to start with.

yeah. I am was concerned, but I was looking for them late base.... down to my lower left. not out the window to my right. I shoul;d have been able to see them late base since that's a white aircraft over green pastures. Looking to the right is looking into the town and beyond into the hills. I dont understand you mention of trafdfic displays showing the situation in the past- certainly the past but no more than a few seconds Which brings me to a defficiency with looking at traffic in OZRWYS - there isnt a time stamp or time delay shown for that fix.

240 mag @ 12-14 kts on ground, IE blowing aircraft on downwind and crosswind wide.

All aircraft were using 15 other aircraft is likely to have gone very deep on crosswind leg, or drifted 1nm on downwind. As we had 1.5nm to 2nm separation (or approx 1 minute) when I was in T&G and other aircraft was crosswind leg and then in late downwind we had zero !

Both GNSS altitude and barometric are available and are transmitted. In the RV, your SE2 has an excellent all round view of the sky.

My experiences are in the PA28 with SE2 on the 2nd pax row seats window behind me. (It's currently up on the instrument panel deck until the GPS-35 antenna is fitted for the xponder). OK I think the GPS wont see well through the wet wings, but through the body would be ok otherwise. To recap- we need satellites from around the whole sky to get a good fix. So SE2 position matters if it is blocked in directions. KG : Those experiments were to determine the practical sensitivity to using an 'outside' antenna, a length of cable, and an inside antenna that is close enough to re-radiate the signal to the SE2 on the bench, inside of my shielded box electronics workshop. AND, performance with multiple antennas to a combiner and then to a re-radiating "coupling" antenna near the SE2. The results are good. I think that it might be possible to get good fixes with just a single 2nd antenna on the other window with a coupling antenna near the SE2. and much better with a third antenna on the nose / instrument panel. The receiver is measuring time delay between sats in order to determine position . To get a accurate GPS fix the receiver needs to be able to see SVs (space vehicles ) around the sky so that it gets diversity . IE if all the sats are around the horizon, the vertical accuracy of the fix will be poor without a satellite overhead . In practice we are not after mm of precision, so we dont need much.. Remember the trig tables, and the relationship with small angles .