Visitor #24778

Flying and Tuning the Zodiac 601XL

Since my first flight on the 17th September 2005, I have had some great fun in the Zodiac. During and after the Phase I testing, I've been tweaking here and there....

Gathering Flight Data

Since my first flight, I've been taking my laptop PC flying with my quite a bit! I can log data from the Dynon D10A EFIS and the Grand Rapids EIS 6000. My Garmin GpsMap296 will store quite a bit of logged data that I download every few weeks.

I import this data into a spreadsheet for graphing and statistics. I'll be posting some of those graphs and data...

Engine:Oil Cooling

It has been rather difficult to get reliable data on engine cooling over the last few months due to the fact that the temperatures outside are so much colder that my initial testing during 95 degree F days!

I have further sealed around my oil cooler opening in the Jabiru cowl with some baffle strip. I already have the fiberglass air dam from Jabiru mounted below the oil cooler on the cowl. With these 2 items in place, I think things should be pretty much optimum

Engine:CHT Cooling

My temps on the first flights, in hot conditions were up over 300F and on to near the limits. Subsequent flights have been MUCH lower! ...but so has the OAT. I put a baffle in front of part of Cyl #1 to 'warm it up' a bit. That seems to have worked very well. I'm still working on this to even things out.
[May 2006 Update]: I've been looking into cooling a little more, I put a small baffle over cyl #6, and an even smaller one over #4. This brought 6 down a bit, and 4 down alot.

Engine:EGT Readings

As posted to the Jabiru Discussion group....
I have a 3300 (newer-with econo kit already in place) on a Zodiac XL, ~55 hours, JabiruUSA FWF kit, grand rapids EIS 6000, 6xCHT probes, 2xEGT probes (on cyl 5 & 6 downpipes). On to the issue. Up to 2650RPM my EGTs will be in the 1300's. Above about 2700RPM to 3000+ RPM my two EGT readings seperate. One will drop to under 1100, the other will go up to 1400. I've posted a file in the files section showing the graph output from my laptop/EIS. Look for "30oct05_chart.JPG EGT Span Issue over 2700 RPM". I've changed my carb induction from a SCAT to a shorter SCAT (better), to a rubber truck hose (better still), two types of flow divider (worse), and a fibreglass cobrahead plenum (worse). I found that with the original SCAT, I'd get rough running at full throttle. The improved smooth tube gives me smooth running through all throttle range, unless I'm over 6000ft or so, where it gets a little lumpy. Sounds like I'm really rich on one side. I suspect many people may be getting a similar issue, but perhaps without multiple EGT probes and an EIS, can't readily see it as graphically.

An update to my previous post. I fitted a slightly different rubber elbow between my Zodiac airbox & 3330. This tube had about a 1.5 inch longer straight portion at the carb after then 90 degree bend. Although the 90 degree bend in this tube was tighter, it straightened out before hitting the carb. This was the 90HL225 or 90L225 hose from http://intakehoses.com/Merchant2/merchant.mvc?Screen=PROD&Store_Code=I&Product_Code=90L225&Category_Code=9DEH I know this has been used by some other builders. After test flying up to 6500ft and graphing the EIS output, I was clear that this was an improvement over my other 'rubber elbow'. Worst EGT span was 189F difference at 3050rpm/6500ft, averaging about 160F difference (1300F on the highest, 1140 on the other). At 2750rpm, the EGT span went down around 130F (highest was about 1230F). At 2600rpm, the EGT's matched (about 1320F). This was the peak EGT I got during the whole flight, and I would imagine the leanest mixture. So a small change in the tube helped a great deal. I don't have great data from my original SCAT tubes (2 attempts), but lets just say you could feel how bad it was! Engine is smooth through all RPM ranges up to 6500ft in this config.

Instruments

I'm using my Grand Rapids EIS6000 for OAT (Outside Air Temperature). The probe is glued into the left side air vent NACA duct. It tends to read high (and climbs with engine temp). I'm looking at relocating it.

My airspeed indicator (both the Dynon EFIS D10A and the steam gauge) indicate high. I'm using the factory pitot/static assembly, in the factory recommended position. I'm gathering data for True Airspeed while I consider my next move. I suspect many Zodiac XL's out there have a similar issue.

Cabin

I finally fitted some carpet to the floor! (i did the baggage floor carpet quite a while ago). This is important in damp conditions, since it was pretty slippery in there with wet feet! I'll post a pic soon.