Apollo AG-1 flight testing data

cburg

Newbie
Hey Abid, nice work. Who's Greg?

Today's Testing (4/24/2014). 4.75 hours
Morning 60 F but foggy, IMC and humid
Late morning 71 F, fog starting to clear to 1000 AGL ceiling, calm winds, takeoff roll was determined to be right around 300 feet at 1145 pounds with use of the pre-rotator on a tarmac runway.

Just above the clouds at 1500 feet MSL, several speed runs with engine RPM were done stabilizing the speed and leveling the aircraft with trim for 30 seconds or more before recording a reading. Yesterdays findings were confirmed for level speeds.

Its fairly easy to cruise at 55 to 87 knots very comfortably. At 90 knots there is some wind that starts to become a little bothersome for the back seat passenger. At 100 knots the wind for the back seat passenger starts to get uncomfortable but not so much that one has their helmet being pulled or anything like that. Just that one can feel the wind swirl in front of them. At 101 knots to 105 knots the front windshield starts to bow at the top. Given low levels of winds in the morning some preliminary verification of Indicated AirSpeed (IAS) was done against the Ground Speed shown on a GPS and it is expected that the error for Indicated airspeed to calibrated airspeed will be within 3%. A proper calibration chart for airspeed is to be developed this weekend following GPS method with tri-angular runs.

Talking to the guys in Europe, they cannot get 105 knots on their gyroplane using same installation with the prop they use. The max they can get is 98 knots. Their climb rate is slightly lower also.

Did a first cross country within the limits of the Op Limitations for Phase-I right to the edge. Engine performed flawlessly. The first signs of fuel starvation happened when the engine had coughed yesterday at about 1.4 US Gallons (5.2 liters) when on final approach, all the fuel went to the forward end and the fuel pickup for the engine which is at the back, sucked in some air and then when power was suddenly applied after touch down the engine coughed but regained fuel supply. That would have to be put down as unusable fuel.
 

fara

AR-1 gyro manufacturer
Were you able to get insurance coverage for it? Typically they have a fleet size threshold.
Haven't talked to Bob Mackey yet but all Apollo trikes are specifically listed eligible for EAA's insurance so I do not think this will be a huge issue. I do not remember them asking me much about fleet size. They were more concerned about support and parts and US facility.
 

cburg

Newbie
I've ran into the fleet size problem a few times. For example I was planning to purchase a Defiant, but the fleet size (19) was a little too small. I really liked that airplane (it's like a twin Push/Pull 4-seat Long-Eze).

http://en.wikipedia.org/wiki/Rutan_Defiant

Haven't talked to Bob Mackey yet but all Apollo trikes are specifically listed eligible for EAA's insurance so I do not think this will be a huge issue. I do not remember them asking me much about fleet size. They were more concerned about support and parts and US facility.
 

ckurz7000

Senior Member
Hi Chris:
I am going to be at the airport at 7 am tomorrow to get very close to ISA conditions if possible.
But why don't you trust the model for fixed wings for data to work for gyroplanes. Is it due to installation errors and static port errors more common in gyroplanes. I am doing a full calibration chart for airspeed every 5 knots to VNe.

P.S. Which model btw are you talking about for fixed wing data
I am talking about reducing take-off and landing distance as well as climb figures. Doing airspeed calibration in non standard conditions is fine. This is simple thermodynamics with no regard of aerodynamics.

I find a well done and careful airspeed calibration to be the foundation upon which most other flight testing builds. How are you doing it? I suggest the 4-leg GPS method. It is the most accurate and has an inbuilt check for consistency. Wouldn't trust anything less.

-- Chris.
 

ckurz7000

Senior Member
For Chris:
I think I have the identical Averso Stella rotor blades as your machine. 27' 10" diameter, 8 7/16" chord.
Can you tell me what you see as climb rate in your testing on the Arrowcopter at 1200 pounds. It would be good to compare for a sanity check while I wait for a standard condition to occur in the ever increasing humidity mornings in FL.
Abid, I see just shy of 800 fpm at maximum gross. In the manual I quote it as 750 fpm to be on the safe side.

I did many test flights to get this right. The key is to have an absolutely thermal free atmosphere. I wound up flying at 5 am in the morning, right at sunrise. Also, starting and stopping the stopwatch myself turned out to introduce significant error because of needing to fly a precise airspeed while watching the altimeter and managing the stopwatch. It can be done but probably requires a lot of practice to achieve good consistency.

At a climb speed of 1000 fpm your climb times for 500 feet altitude will be around 30 seconds. It's easy to make an error of 1-2 seconds starting and stopping the watch. That'll introduce an error in the neighborhood of 10% right there.

What worked out great was to use the data recording built into the EFIS. This records airspeed, altitude, VSI and time (among many other parameters). Then I used Excel to filter data and only use data in which airspeed was within +/- 2 kts over at least 250 feet of altitude. I also discarded data in which the VSI wasn't settled down yet (e.g., after pulling up into a climb).

If you don't have an EFIS, get yourself a 10Hz GPS data logger from an RC supply store (e.g. www.hobbyking.com). That's probably the best investment you can make for flight testing. You will get altitude, ground speed and VSI at 0.1s intervals. You still need to record airspeed but that's no biggie. Just keep it within 2 kts of target.

However, even weak thermals would muddle the data significantly. I am now at a point where I question climb data flown during the day.

-- Chris.
 
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ckurz7000

Senior Member
fara said:
A proper calibration chart for airspeed is to be developed this weekend following GPS method with tri-angular runs.
My advice: spend a lot of time calibrating the ASI properly. This is what all subsequent numbers and speeds are based on.

Also, use the square course method instead of the triangular course method. You will get one data point per triangular course but with only one course more you get 4 data points! If the spread in the 4 data points is larger than 2 kts you know that you can probably chuck the data point.

I think you know all this, but it doesn't hurt repeating: don't calibrate against GPS ground speed!! You need to convert the ground speed to Equivalent Air Speed (EAS) taking into account density altitude (you can neglect compressibility at these low speeds). This you compare to IAS also corrected to EAS. So you wind up comparing two EAS and not IAS to GS!

-- Chris.
 

ckurz7000

Senior Member
Actually, no, Chris. Mine looks smaller and without a display. And it records 10 data points per second. It isn't really mine; I got it from an RC aficionado. I just know that Hobbyking carried.

It is good to have the 10Hz data recording frequency. This helps in determining start- and landing distance better. Apart from that a 1Hz unit would suffice.

-- Chris.
 

fara

AR-1 gyro manufacturer
Abid, I see just shy of 800 fpm at maximum gross. In the manual I quote it as 750 fpm to be on the safe side.

I did many test flights to get this right. The key is to have an absolutely thermal free atmosphere. I wound up flying at 5 am in the morning, right at sunrise. Also, starting and stopping the stopwatch myself turned out to introduce significant error because of needing to fly a precise airspeed while watching the altimeter and managing the stopwatch. It can be done but probably requires a lot of practice to achieve good consistency.

At a climb speed of 1000 fpm your climb times for 500 feet altitude will be around 30 seconds. It's easy to make an error of 1-2 seconds starting and stopping the watch. That'll introduce an error in the neighborhood of 10% right there.

What worked out great was to use the data recording built into the EFIS. This records airspeed, altitude, VSI and time (among many other parameters). Then I used Excel to filter data and only use data in which airspeed was within +/- 2 kts over at least 250 feet of altitude. I also discarded data in which the VSI wasn't settled down yet (e.g., after pulling up into a climb).

If you don't have an EFIS, get yourself a 10Hz GPS data logger from an RC supply store (e.g. www.hobbyking.com). That's probably the best investment you can make for flight testing. You will get altitude, ground speed and VSI at 0.1s intervals. You still need to record airspeed but that's no biggie. Just keep it within 2 kts of target.

However, even weak thermals would muddle the data significantly. I am now at a point where I question climb data flown during the day.

-- Chris.
Hi Chris:
Thanks and appreciate the guidance. I will fly the 4 course method.
I have used both 3 leg and 4 leg ASI calibration method. To me both seem to work as long as done carefully.
http://www.aero.polimi.it/~chimetto/bacheca/downloads/docs/GPSPEC.pdf

We have flown off the 40 hours Phase-I now so can take a second person to record data and do other tasks.

For climbs I always had two people in the aircraft because it is really next to impossible to get proper results with just the pilot recording.

I actually have access to a sealed certified GPS data logger that we used for speed record attempts with FAI and actually broke 3 records in microlight class and then got rejected due to a technicality (the US FAI observer that they selected did not know that he should have weighed the machines with the pilots in it to make sure it didn't go over 450 kg, what a crap load of BS, like that was our fault). I should use that thing. Cost about $1500 better use it. This one at Hobby King at $51 is cheap.
https://www.youtube.com/watch?v=3sMdeXFxwBk
 
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fara

AR-1 gyro manufacturer
Hi All:
Ok. I have some more certain finalized numbers. It is amazing that even yesterday morning very early we had basically very close to standard conditions in Zephyrhills at 60 F. Later it got to 86 F in the day.

Data for Standard Sea Level Conditions.

Rotor System: Averso Stella 27' 10" span, 8 7/16" chord
Pre-Rotator and Brake: Pneumatic
Prop: Sterna 3-blade composite, 70" diameter
Pre-Rotator able to get to: 270 RRPM fairly quickly and easily, recommend using 220 RRPM on a regular basis as normal procedure

Airspeed Indicated versus Calibrated -- Across the range the largest difference was 3% error (within specifications for something like Part 23)

Climb Rate (One up, 10 gallons of fuel, 175 lb pilot): 1350 FPM
Climb Rate (Two up, full gas, weight 1190 lbs): 900 FPM
Static RPM on Prop: 5400 (16.1 deg pitch at 75% station)

Following cruise speeds are given 2-up close to 1200 pounds weight. One up numbers were lower.
Cruise Speed (~5150 RPM): 87 knots - Fuel Burn: 5.6 GPH
Cruise Speed (~4700 RPM): 75 knots - Fuel Burn: 4.2 GPH
Cruise Speed (~4300 RPM): 65 Knots - Fuel Burn: ~ 3.3 GPH

Cruise Range at economy cruise: 317 statue miles with 30 minute reserve
Cruise Range at 75 knots: 280 statue miles with 30 minute reserve
Cruise Range at 87 Knots: 270 statue miles with 30 minute reserve

Vh: 106 knots

I invite anyone interested to come and take a flight to see the results for themselves. Some on this forum have already had a ride in this gyroplane hopefully more to come.
 
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martin-av8r

Member
i am realy impressed with this machine performance and cruise speed for fuel burn for a open machine gyro very good new player
 

Resasi

Gold Supporter
Abid and Chris, it is both encouraging and interesting to see your efforts in obtaining very accurate results.
 

Steven

Awe Inspiring Human
Arrowcopter prop

Arrowcopter prop

Does anyone know which manufacturer Arrowcopter uses for their 2 blade prop?
It looks highly twisted nearer the root and has the same tip design as the DUC and Prince P tip. I wonder about the noise their 2 blade prop produces?
 

Fly Army

Member
Does anyone know which manufacturer Arrowcopter uses for their 2 blade prop?
It looks highly twisted nearer the root and has the same tip design as the DUC and Prince P tip. I wonder about the noise their 2 blade prop produces?
I believe Arrowcopter makes their own prop.
 
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