Air Command 447 flight test problem

dwood2066

Newbie
I recently restored an Air Command 447. The engine is an overhauled Rotax 447 with a 4 blade Ultraprop, I used McCutchen 25ft blades. The first flight resulted in the copter only rising about ten feet in the air at max power and could not rise any higher. So my questions are - Is this a horsepower problem? Or a prop thrust problem? Or a too heavy or too long blade problem? Any input out there will be a great help!
 

Cresco750

Newbie
My experience with fixed wing ultralights many years ago found that Ultraprop’s did not produce nearly as much thrust as an equivalent Ivoprop, Warpdrive, or any other prop that we we tried.
 

jany77

Member
There have been probably hundreds of air command flying with 447 rotax and same prop with no issues ,I think the problem might be somewhere else specially if it flew like that before ,it would help if you can give us more data such as field elevation ,temperature the day you flew ,empty weight of the machine ,your weight etc .
 

AirCommandPilot

Just a fledgeling
I thought the 447 Commander originally had a 23' rotor. Would the added weight of a 25' rotor do this? My 25' Skywheels weigh 69 lbs.
 

WaspAir

Supreme Allied Gyro CFI
Another question to add to the list:
What airspeed did you have at that 10ft max altitude?
(One can pop up and fly in ground effect at very low speed but be also too slow to climb out of ground effect.)
 

WaspAir

Supreme Allied Gyro CFI
AirCommandPilot;n1136363 said:
I thought the 447 Commander originally had a 23' rotor. Would the added weight of a 25' rotor do this? My 25' Skywheels weigh 69 lbs.
Your Skywheels are less than three pounds per foot of span with the numbers you report. I would expect that the weight difference can't be much from adding an extra 2 feet of blade (perhaps 5 pounds net). There will be other rpm and handling differences with rotor diameter, but the weight change alone isn't much of a factor, and if flight capability is so marginal that plus or minus a couple pounds means climb or no climb, other things need to be addressed. A gallon of gas in the tank is about that much, or a week on Weight Watchers for the pilot.
 

Joe Pires

star hoarder
dwood2066;n1136340 said:
I recently restored an Air Command 447. The engine is an overhauled Rotax 447 with a 4 blade Ultraprop, I used McCutchen 25ft blades. The first flight resulted in the copter only rising about ten feet in the air at max power and could not rise any higher. So my questions are - Is this a horsepower problem? Or a prop thrust problem? Or a too heavy or too long blade problem? Any input out there will be a great help!
Hi, seems this is your first post...welcome to the forum. What experience, ratings, training, do you have in gyroplanes? Your problem may not be your equipment so if we can eliminate factors of your knowlege/experience it might make it easier to zero in on the issue.
 

dwood2066

Newbie
WaspAir;n1136374 said:
Another question to add to the list:
What airspeed did you have at that 10ft max altitude?
(One can pop up and fly in ground effect at very low speed but be also too slow to climb out of ground effect.)
Max speed was 30mph, at 6700rpm. Engine was maxed out.
 

dwood2066

Newbie
Cresco750;n1136342 said:
My experience with fixed wing ultralights many years ago found that Ultraprop’s did not produce nearly as much thrust as an equivalent Ivoprop, Warpdrive, or any other prop that we we tried.
I am going to try a 2 blade at 60in and see what happens.
 

dwood2066

Newbie
WaspAir;n1136375 said:
Your Skywheels are less than three pounds per foot of span with the numbers you report. I would expect that the weight difference can't be much from adding an extra 2 feet of blade (perhaps 5 pounds net). There will be other rpm and handling differences with rotor diameter, but the weight change alone isn't much of a factor, and if flight capability is so marginal that plus or minus a couple pounds means climb or no climb, other things need to be addressed. A gallon of gas in the tank is about that much, or a week on Weight Watchers for the pilot.
I am only 170lbs, it seems like it would should handle that much.
 

dwood2066

Newbie
AirCommandPilot;n1136363 said:
I thought the 447 Commander originally had a 23' rotor. Would the added weight of a 25' rotor do this? My 25' Skywheels weigh 69 lbs.
An extra 2ft on the blades can add that much more weight can it? Not enough to keep from lifting higher that 10 feet?
 

Vance

Gyroplane CFI
In my opinion you didn't get higher than ten feet because you don't understand how to fly a gyroplane.

Please get some instruction before you hurt yourself.
 

Tyger

Active Member
dwood2066;n1136563 said:
Max speed was 30mph, at 6700rpm. Engine was maxed out.
I don't think it's your equipment. It sounds to me like you were flying way behind your power curve. Not too many gyros are going to be doing much climbing at just 30mph even at max power setting.
 
Tyger;n1136597 said:
I don't think it's your equipment. It sounds to me like you were flying way behind your power curve. Not too many gyros are going to be doing much climbing at just 30mph even at max power setting.
Derrek,
What is your V[SUB]Y [/SUB]?
If you do have not already have this number memorized, Please follow Vance's recommendation.


Vance;n1136584 said:
In my opinion you didn't get higher than ten feet because you don't understand how to fly a gyroplane.

Please get some instruction before you hurt yourself.
We are not trying to Beat You UP, we are trying to save you, Buddy!
 

Doug Riley

Platinum Member
A 447 A.C. won't climb at 30 mph. 40 or above. I weigh the same as you and put hundreds of hours on mine. It is not a rocket, but it will climb.

Make certain you have the proper pitch blocks on the Ultra. I believe the A.C. used 13-degree blocks, but others will know better.

The Ultra is not an ideal prop because (1) the leading edges are sharp when they should be rounded (2) the blades are untwisted. As other posters have noted, there are better-performing props.

25 feet is an awful lot of rotor for such a light gyro. Dennis Fetters tried 25-footers on the A.C. 447 but settled on 23's. A rotor that is is too lightly loaded will spin too slowly, which creates a cluster of problems.

Two LIFE and DEATH safety tips:

(1) get some good gyro training. If you're trying to make a 447 climb at 30, your training was not thorough enough!

(2) make certain that you have a horizontal stabilizer on your gyro. The factory job works nicely. Without a stab, an Air Command lowrider is a proven widowmaker! Its prop thrustline is 5-6" above its CG, making it extremely prone to power pushover (PPO). And, anyway, it handles far better with the stab. Night and day, in fact.
 
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