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twistair
06-30-2010, 11:36 AM
As we discussed with Chris (ckurz7000) I started today some performance testing which may be interesting for somebody.
First was to see how true ASI shows our airspeed.
Test environment was:
Calidus gyro/Rotax-912ULS/IVOprop Medium inflight adjustable prop
Load: 170 kg crew+20 kg fuel
OAT +24C
500 feet density altitude

Measurements taken by GPS at a triangle base keeping constant IAS during all three legs. IAS pitch was 10 kmh from 50 through 170 kmh. After that field results were filed and CAS was calculated:

Results (kmh):
IAS CAS %%
50 47.0 0.94
60 58.3 0.97
70 66.3 0.95
80 78.7 0.98
90 86.7 0.96
100 100.0 1.00
110 109.7 1.00
120 120.0 1.00
130 134.7 1.04
140 143.7 1.03
150 154.3 1.03
160 165.3 1.03
170 173.7 1.02

Sorry for metric units :)

To be true these measurements may have some deviation from reality since it was my first experience in such measurements so we simply made them in two flights to become familiar with procedure itself. Tomorrow I'll try to repeat them more precisely.
Anyway correlation looks more or less real.

GrantR
06-30-2010, 12:07 PM
Alex what is your cruise speed and engine rpm?

twistair
06-30-2010, 12:32 PM
Alex what is your cruise speed and engine rpm?

Don't know yet :eek:
POH states 160 kmh (100 mph) cruise and my goal is to find best combination(s) of speed, IVOprop pitch and engine rpm
This should be next portion of studying this gyro habits.
Today I flew with a medium weight (85 kg) pax, it flies 150-160 kmh at something like 4900...5100 rpm at what looks to be medium increased prop pitch. IVO has no indication of pitch attitude so one of goals is to understand how to operate it in most efficient and safe way. I mean "safe" both for crew and for engine i.e. how not forget to decrease pitch before take-off or before flying at low altitudes and how not to kill the engine at high pitch settings.
I never used inflight adjustable props so this is completely new story for me.
I read with great interest what Chris wrote about his study for MT-03 and want to do same things for Calidus now.

GrantR
06-30-2010, 01:52 PM
That is pretty impressive speeds for a gyro. You gyro looks like it should fly fast. :)

twistair
06-30-2010, 02:23 PM
I'd say it flies as it looks ;)
These days some of my passengers were experienced homebuilders of fixed wing aircraft. We here call them "profi homebuilders" since they are really professional aircraft engineers. These guys really know what is good and what's not. They all told that they feel very comfortable in this gyro.
First thing I noticed comparing to other gyros I flew before is that it flies equally comfortable at all speeds within POH limits. Sitting inside you never know by noise or vibration change what is your speed - 60 or 160 kmh. Good thing it has ASI in it :)

ckurz7000
06-30-2010, 11:22 PM
Alex, I can confirm your experience: the Calidus flies very predictably and without any bad habits that I could discern over the entire speed range from 60-180 km/h.

When you do your three leg course to determine the ASI calibration, it is actually best to fly a fourth leg. That will give you 3 data points instead of only one. You get much improved data integrity with flying only a sinle additional leg. In my experience it is absolutely important to fly straight and level. Judging this by altimeter alone was not good enough for me. I am using a VSI. Without it, my speeds would be off by 5-10 km/h, particularly at the higher speeds.

I hope to get some flying in today. Am planning to look at cruise performance vs. prop pitch and rpm.

It's great to have someone else repeat the measurements!

npubem, -- Chris.

twistair
06-30-2010, 11:36 PM
I also use VSI for level flight. What I'm now thinking about is to install fuel flow gauge to see actual fuel consumption at different settings.
Plan to make some more flying today repeating ASI calibrating then will be off flying till Monday.

Resasi
07-01-2010, 02:04 AM
Interesting following this flight testing, the methods used and the results you two are achieving. Thank you both for allowing us to follow it.

Just a huge shame my chances of flying this machine are so small.:ohwell:

twistair
07-01-2010, 02:17 AM
Anyway they aren't zero.
What if next time Chris wants to look for homeopaty weed in Africa? Or if my little lady wants me to show her something interesting slightly south (6300 km) from Moscow ;)

Resasi
07-01-2010, 02:21 AM
Now that made me smile Alex. One lives in hope. Now I must get ready and see about going to fix a gyro.

ckurz7000
07-04-2010, 12:42 PM
On Friday I flew a couple of exploratory test flights to get data for cruise performance of the Calidus with the Ivoprop.

Just to be clear on my defintion for prop pitch and how I set it:

I dial in maximum fine pitch (mfp) and adjust throttle to 5000 rpm in straight and level flight. This is my reference point from which I begin changing the pitch. When I increase the pitch, engine rpm will drop. Everything else (i.e., flight attitude and power setting) remaining the same, the drop in engine rpm is a measure of the pitch. So, in my definition, a pitch of p=500 means a pitch setting on the Ivo, which will result in 4500 rpm (i.e., in a drop of 500 rpm) when starting at mfp, straight and level, and 5000 rpm.

I explored the data between rpm: 4000-5000 and pitch: 0-500. My results seem to indicate that I need to extend the range of pitch to 750 or maybe even 1000. My maximum cruise so far was 180 km/h, which is within a couple of km/h of Vne.

Incidentally: I fly these tests at a pressure altitude of 3000 feet. 31 °C, 1018 hPa altimeter setting, 21 °C dew point and a field elevation of 440 feet yield a density altitude of 2500 feet on the ground. So I flew my test at 500 feet AGL, which results in a density altitude of pretty close to 3000 feet. I will adjust my AGL altitude so that all cruise performance tests are at a density altitude of 3000 feet. With 36 liters of fuel and some baggage beside myself I was up at 380 kg of take off mass.

I hope to flesh out my data sometime over the week.

Greetings, -- Chris.

OzyRuss
07-04-2010, 04:01 PM
Fuel flow at ???? engine / prop settings would be interesting, also manifold press settings.

ckurz7000
07-04-2010, 10:23 PM
Fuel flow at ???? engine / prop settings would be interesting, also manifold press settings.

Since I have a fuel flow gauge but no manifold pressure gauge I am recording fuel flow.

For each combination of rpm and pitch I record IAS and FF.

Greetings, -- Chris.