da 70 thread

[Bunky.F.Knuckle]

Do yourself a favor, and ditch the engine telemetry. You are causing yourself nothing but grief over this. If you listen to the engine, and understand what you are listening for, your engine will be happy. It is very hard to describe via a web forum what to listen for. I can't stand telemetry. I feel it needs to be taken out of the radio systems, period. It seems like if you see a high temp, you are trying to make it cooler by richening the needles. You are chasing your tail, to say the least.



I do not and will not fly an airplane with engine telemetry. Why?? I don't want to listen to the beeping of the radio while I'm flying 3D!



I will however, use these, if I'm unsure of a tune.... http://www.horizonhobby.com/products/on-board-temp-gauge-tg3-MIP2090 Once you get the tune right, don't F with the needles and have fun! Another tuning measure is reading the plugs.



Point of interest, from the weekend in Chattanooga. I drove down to pick up a new airplane. Listened to a DA 150 that sounded like absolute junk! Low end was slow to transition and quit on the ground at an idle. Sounded like it was firing on 1 cylinder. I checked the exhaust temps by hand, and one side felt cooler than the other. Told the owner, lets check the plugs. Well, wasn't firing on 1 cylinder. It was a tuning issue. Plugs were pretty carboned up. Put new plugs in, and I made a small L needle change. Fired it up, was better, made a couple more tweeks to the needles, and it sounded like a new machine. No telemetry on that airplane. Just a couple of good ears listening at something that didn't sound right.

 

[orthobird]

Hi Bunky, sorry for the confusion. the motor came back from DA and i did not touch the needles, however, it sounded terrible. this is without anything to do with the telemetry. i kept leaning it, and it kept sounding and performing better, except for the last two flights, which were longer than the 1st 3, due to it performing better, that i believe there may be an issue with the "plumbing", i am not concerned about the temp differences between the two cylinders, and my transmitter also will not alarm me of anything, unless i ask it to (by tilting the Transmitter). i like to see the temps, only because i know if it gets over 450, i will be looking at a deadstick soon. with that said, i do not use the telemetry in any way to tune, it is all based on sound, as you mentioned. seems to me, that in this engine in particular, since day 1, it has spit out a ton of oil. do not know what that means. i have never had any other gas engine spit out this much oil. today, after the flights, i took down the tank and redid all the fuel lines and the tank..maybe tomorrow the Mrs. will let me fly it.

 

[Bdegan]

I do have to agree with you on the telemetry. A bunch of us were just talking about that the other day.

If does seem to cause more worry and grief than its actual value LOL.

I do tune my engines with my ears and my eyes.but I still like telemetry because it can be used as a tool that can help trouble shoot at times.

 

[orthobird]

i agree with both of you. i perform hip and knee replacements, and the best knee is the one that comes out with full range of motion and with symmetrical flexion and extension gaps and the matching rotation of the implants. with that said, the surgery can be done with using carpenters tools and your eyes and your sense of tension and symmetry, using your own senses. and, they have all kinds of expensive high tech different technology, with either computer navigation, robotic surgery, pre-surgical planning and patient matched implants, etc...



but with all this technology, the best surgery is the one where the surgeon still uses his brain and uses his senses to assure it comes out good, and if the surgeon relies solely on this "technology" be prepared for all kinds of errors.



my 2 cents!!!

:shaking-hands-smile

 

[Bdegan]

It's funny you mention spitting oil. In the other thread where I posted a video of my 70 on pipes.

You will see it blowing lots of smoke at full throttle. We tried to lean it to stop the smoke at full throttle. But the engine rpm would drop. The engine ran at its peak with smoke blowing out.

My DA60 was the same . Against a blue sky on a full throttle up line. The 60 had a smoke trail. If i tried to tune that out. There was an rpm drop.

It was happiest with a slight smoke trail.

Not sure why. Just the way it was.

 

[orthobird]

Bdegan;10290 wrote: It's funny you mention spitting oil. In the other thread where I posted a video of my 70 on pipes.

You will see it blowing lots of smoke at full throttle. We tried to lean it to stop the smoke at full throttle. But the engine rpm would drop. The engine ran at its peak with smoke blowing out.

My DA60 was the same . Against a blue sky on a full throttle up line. The 60 had a smoke trail. If i tried to tune that out. There was an rpm drop.

It was happiest with a slight smoke trail.

Not sure why. Just the way it was.

must be a reason for this, but i cannot explain it.

 

[orthobird]

great news!!! just flew my 91" yak with the da 70, 3 times today! i had changed out the gas tank and all the tubings, and now, not a hiccup. no fading, 1st flight, she was quite rich low and high. after 1st flight, i leaned the low end by 1/8th turn. 2nd flight was better, still rich high and low, then i leaned in the high by 1/8th turn. 3rd flight best ever, still rich on high end just a tad bit, but i will leave it as is for now. still lots of oil on the bottom of my airframe. 3rd flight, long uplines, no fading. once i had some confidence, i decided to do some harrier flight and hovering about 20 feet altitude, and she did amazingly great. very good midrange!! i am happy now.

telemetry data to follow:

 

[orthobird]

yak 91" ef, DA 70

ambient temp = 97 F

prop= falcon 24 x 10

40 to 1 redline

93 octane = no ethanol

altitude is 260 feet above sea level





flight number 1 = high rpm (during flight) 7770

idle rpm 2800

flight time= 10. 3 minutes

peak Temp 350.9 F right cylinder

peak temp 293.8 F left cylinder





flight number 2 = high rpm (during flight) 7950

idle rpm 2340

flight time= 12.8 minutes

peak Temp 354.9 F right cylinder

peak temp 305.7 F left cylinder





flight number 3 = high rpm (during flight) 7830

idle rpm 2420

flight time= 15.8 minutes

peak Temp 332.6 F right cylinder

peak temp 301.1 F left cylinder