rhtrudder

Thanks 

Maybe end up going through the week 

Hi anyone flown the VFR track through Nowra , I’ll be heading south, wondering if it’s easy enough, Greg 

At around 4500 revs my engine definitely has increased vibration ,below 4000 and above 5000 it’s good , I think I come across this in another thread, it’s fitted with a O2 sensor so I know the mixture is correct, prop been balanced,  could this be harmonics , has anyone else come across this 

Quote

 

Noticed a soft compression one one cylinder so ran through a leak down test sat the gauge on 80 , three read 77psi but the sick one was down to 75 psi , I guess not a lot of difference, could hear a faint bubble in the oil tank , engine has 1850 hrs up, would a set of rings an a hone fix this , back in my 2 stroke days rebored to get everything round , engine is a 914

On 31/5/2023 at 12:25 PM, RFguy said:

SKyecho might have a high grade GPS, but a low grade antenna AND on the window of an aircraft leads to some very large transmitted GPS errors.

I see this from time to time (see below) note track errors. I have checked the received GPS stamps in the  logs from  the skyecho, it appears to be sending position data when the GPS fix is very poor- It should not do that, I am going to write to Uavionix.
  I am going to move it from a back window to just ahead of the compass on the panel, where it has a better view of the sky.

So, with respect to separation - always consider that an airplane with a skyecho might be a few hundred meters out !!! And vertical performance might be even worse.

There is a reason that TSO GPS ships require a GPS in an optimal spot - external along  the roof line.  I do not see such gross errors in aircraft flying with TSO GPS+antenna.

 

 

 

Dumb question, but how do you access the track logs from the skyecho 

10 hours ago, RFguy said:

Mostly, for simple series motors,  the reverse is handled by a cross wiring arrangement on the back of a DPDT centre off toggle switch
+ and - go to the switch, and two wires go to the motor.

 

Some motors have three wires, which becomes 1 common and direction selection. There might be a common ground (return) , and two positives (one for each direction) . Or the positive might be common, and have two switched returns.

if it doesnt always work, check that there is sufficient voltage at the motor (pair of crocodile clips etc and a multimeter) , watch the voltage when it stalls or doesnt move. 

THE OTHER thing is, all motors will have (or should have)   microswitch limit switches- you might have a dicky switch / actuator causing the system to think it is end of travel when it is not.

Failing all that, do a no load test on the motor- IE without the crank connected and see if it behaves. 
-glen

If there is a DPDT switch could that be the problem, not easy to get to the trim motor 

Sorry should have said it’s on the elevator, I’ve got manual flaps

Trouble is the thing only stops working in the air, would be better if it didn’t work at all, it has 5 wires, I think 3 are for the indicator 

Having intermittent problem with my up trim , down works always but up stops now and then, don’t think it’s in the switch, pulled apart and looks ok, can sometimes get it to work if I touch the down trim , not sure how to the thing is wired, looked up a  wiring diagram and looks like it earths out back at the switch but I can’t figure out how it reverses the polarity , would there be another relay or controller to do that, there is a birds nest of wiring behind the panel so not easy to trace 

Okay, you’ve talked me out of it, thanks 

It took a few rinses to get rid of the frothy water, the plastic looks as solid as my other petrol containers 

Okay, they had roundup or glyphosate in them , probably just as corrosive as petrol maybe

Can anyone see a problem using plastic 20 lt ag chemical containers to store petrol in , have got plenty to choose from 

Have replaced the throttle cables with good quality ones, smooth operation, carby balance looks good, at 5000 revs the butterflies would be nearly fully open , engine revs to redline on takeoff, has a inflight adjustable, if I run it at 5300 it’s good but when I pull it back to 5000 it’s very noticeable , I thought if the prop was out it would vibrate through the whole range, I’ll get it checked anyway 

Noticed Engine vibes  between 4500 and 5000 , above and below, all good, Carbys just done , gearbox recently done, could it be prop balance 

If you let your RAA membership lapse for a number of years do you have to go through all the training to be able to start flying again , son has lost interest but hopefully take it up again some time in the future 

2 hours ago, RFguy said:

So ! oxygen sensors....
They seem to be located on the headers where the cylinders combine.
some are exhaust heated (must get to min 350C, pref 500C)
most with more than 2 wires are internal heater type (a couple of amps at 12V) .

and wideband are 5 wire usually. has a current output and requires 2-5 V depending on the sensor + heater. 
I bought a wideband sensor from ebay. we'll see what it does eh ?
But if you want simple : use a narrow band sensor. IE you just get a "above stoich" and "below stoich" output. VERY simple to use with just a multimeter reading voltage.   and a 12V source for the heater. 
wideband sensor provides more 'linear' output  from rich to lean- but most cars just want to know if they need to go one way or the other.
Titanium sensors (rather than zirconia) more tolerant of crap in the gas. 

 

I ended up welding the plug at the start of the tail pipe where it leaves the muffler , leaves about 300mm to the end hopefully will get a good enough reading, 

2 hours ago, RFguy said:

but he's  a rotax owner Don, when a set of rings for a rotax is $250, money is no object.  (I just bought 6 ring sets for a jab project for less than the cost of a single ring set for the rotax) .

Money is a bit of an object more so when I got charged $400 for the floats

1 hour ago, facthunter said:

He's only relating a fact. Some people can buy a product knowing  and acknowledging some of the downsides. Everything to do with a Rotax 9 series COSTS. The Chinese copy is no doubt cheaper. That doesn't mean I'd buy one or a 914.. Getting a good motor for a U/L is not easy. Fit and forget is a vague hope. Often an ancillary component lets a good motor down. Gravity feed is better than the best fuel pump.. If you need a pile of instruments to monitor your motor, get a less sensitive motor. It shouldn't be rocket science. mDo you want to be a Flight engineer OR a Pilot. All planes need a pilot. At the moment and IF  they don't WE DON"T want it because we want to FLY don't we?   MAN & Machine not man riding in machine. Nev

Understand, but I have a 914 , that’s not about to change, I do like to fly it and have the engine run sweet  if that means doing a bit of tinkering I’m more than happy to do that, not sure why all the capitals 

2 hours ago, Methusala said:

Hey mate, you can buy O2 sensors with digital gauge for about 40 dollars off ebay. Why pay more when you only want it as a diagnostic indicator? Just my 2c worth.

Rgds Don. PS. I used one when setting up EFI on a Aeropower vw conversion.

Did know that, apparently big difference between wide and narrow band , I’m a farmer so I’m used to throwing money away, 

23 hours ago, RFguy said:

rightio then , sounds like just needs methodical approach to figure out what is going on. Yeah the O2 sensor (ULP only - no lead) would be a handy diagnostic I think.

I’m restricted on where I can fit the sensor, do you think it would get a good enough reading in the end of the muffler, the tail pipe is to small in diameter I reckon, the other end is taken up by the turbo body 

Hope so, just paid for it, I’ll keep you posted, I’ve ordered a bung as well so I can plug it off, was told they don’t like lead, mostly run 98

48 minutes ago, RFguy said:

This is a good read

https://www.rotax-owner.com/pdf/UNDERSTANDING THE 914 ROTAX.pdf

 

Particularly sections : 

the ENRICHER SOLENOID SECTION (9)
and FUEL REGULATOR- AIR BOX PRESSURE (14) 

 

Rudder - take a good look at those two sections. I reckon you will find your demon there. 

Yep, I do understand how that all works, had trouble once before with Leakey bowls , engine hesitation in the boost range, the enricher valve opens at full throttle to direct higher pressure into the bowls, tapped into a port closer to the turbo, fuel pressure is kept just above air box by the regulator, I have the understanding the 914 saved , spell’s it out pretty good 

Yep, prop fine, 4800 rpm, map 28, haven’t got fuel flow , air speed around 90 that’s where it runs rough which I now check every time I take it up , 

cruise is 5400 , map 35 gives close to 120kn, runs okay,  just thought a O2 sensor might show exactly what’s going on , cost $400, haven’t ordered it yet, , the YouTube video looked impressive, showed where the engine was lacking , maybe I’ll just put up with it,