Justin's Raven

[justin.schoeman]

Anybody else getting slightly peeved with this weather? Seems flyable weather and test pilot availability are a rare combinations .

[Pietb]

Anybody else getting slightly peeved with this weather? Seems flyable weather and test pilot availability are a rare combinations .

!!

Need to ferry a plane from Vereeniging to Petit...also struggling for a few days now !!

[justin.schoeman]

Yup. Weather reports don't help much either. If they say it will be clear, it will rain. If they say rain, it will be clear (but probably with a howling wind). Just can't plan ahead.

[Pietb]

Yup. Weather reports don't help much either. If they say it will be clear, it will rain. If they say rain, it will be clear (but probably with a howling wind). Just can't plan ahead.

Absolutely !!

[justin.schoeman]

OK - Finally got a test flight in on Saturday morning. Unfortunately, the MGL for some unknown reason decided not to record the flight data (the Xtreme works perfectly, but flight data recording seems remarkably unreliable for some reason).

I have got the basic numbers though, and it looks good! Still have some work on the EGTs though, with a 100C imbalance swinging left, to right and back again at various throttle settings. CHTs are good - highest was 182C on #5 in a partial throttle climb - but generally all are around 160C, or less.

Take-off run at around 480kg was ~350m. Climb out at 80KIAS is 800fpm (Vy is around 65KIAS - so there is still a lot more in the bank, if you like looking straight up into the sky).

Still need to figure out optimum cruise. Seems most comfortable at around 95KIAS at 2850RPM (17" MAP). Full taps gives 107KIAS at 3270RPM (22" MAP).

Prop needs some work, as I am a little close to red line at the moment (full throttle, straight and level).

I am trying to order another 4 EGT probes from MGL at the moment - would like to instrument all 6 cylinders and see what is happening with those wild EGT swings. Will hopefully take leave sometime this week to install them, and test again on Saturday.

[t-bird]

Hi Justin
Are the paperwork done and will you be able to do the rest of the testfying ?

I assume that the recording of the egts are only a nice to have and not a requirement.

Regards

[justin.schoeman]

Hi Justin
Are the paperwork done and will you be able to do the rest of the testfying ?

I assume that the recording of the egts are only a nice to have and not a requirement.

Regards

Unfortunately, Cyril was not happy to sign it off until the EGTs are within limits.

[AndyCAP]

Hey Justin. Whats news?

[Jean Crous]

Ja ek wil ook weet
J

[justin.schoeman]

Still fighting with temps. I have now installed EGT probes on all cylinders, so I have a much better idea of what is going on. Turns out the main problem is at full throttle, where there is little turbulence from the butterfly. In this condition the EGTs just go crazy. Len has a simple solution though - just close the throttle a tiny bit, and everything will come right.

#5 CHT was also borderline, but I think I may have it sorted now. Fitted some inter-cylinder baffles (formed on top of the cylinders, but installed underneath):

Makes a massive difference on the ground runs - still need to see what it does in the air though.

Unfortunately, until I have the temps safe, the test pilot will not sign it out. So this testing is horribly slow. Need to wait for a weather break + test pilot to be available at the same time. And now he is away until January - so will not be much more progress until then.

[Jean Crous]

Justin those baffles are called "forget-me-not plates" and with good reason, you have now discovered why I know Jabiru does not come with them, but I am 100% convinced if all Jabi engines have them , there will be no more cylinder and head issues
Jean

[justin.schoeman]

Justin those baffles are called "forget-me-not plates" and with good reason, you have now discovered why I know Jabiru does not come with them, but I am 100% convinced if all Jabi engines have them , there will be no more cylinder and head issues
Jean

Yup. The Jabi installation manual doesn't really want you to install them... Says only to install them if you have CHT issues without them. But then, it also says you must install them on top of the cylinders!

Hammered some 1020 sheet to tightly fit the contours of the cylinders - so they have a much better fit than jabiru's recommended angles...

[Jean Crous]

I like the way that "ingenieur brain" of yours works
Jean

[justin.schoeman]

OK - tried every trick I could find today - all in one go. Added ramps over the vertical plates in front of #1 and #2. Drilled the air dam above #3 and #4 into swiss cheese. Added lips to the cowl exit area.

Not sure which worked, but temps are OK now. With an OAT of 27C, I climbed 1000' with the highest temp at 175C. Temp was fine at all cruise settings, and only 165C at best cruise (2750RPM, 88KIAS).

Still some work to do. #1 and #2 are too cold, so I need to raise the ramps a bit. #4 is also a bit cold, so cut away some of the air dam. But at least I can safely fly the plane now.

EGTs are OK ish. They go all over the place at full taps, but Len says this is normal. Just reduce throttle a hair and they all come back. At cruise settings, everything is pretty even.

All in all, I think I am getting there.

Booking an extended session with Cyril next Saturday to get some rust off - need to learn to land this beastie again .

[Induna]

Nice one! Ravens fly so nice and is a pleasure to land, so don't sweat too much..!

Me and my better half had a nice Sunday afternoon cruise with my Raven Tailly and it was awesome!

Enjoy flying your Raven... Such nice aircraft.

Jacques