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30, 2009
Update July 17, 2009
Today Lee and I went up and took our spin evaluation of the Bearhawk a little further. Now that it's getting into summer, it's getting hotter here in South Mississippi, so we have been going up in the mornings. Today we went up and did some spins from about 8500 feet. To help us keep a good track of the number of turns we set up right over a long straight stretch of a 4 lane divided highway. We are still testing the spins at a forward CG with Lee and I plus about 3/4 tanks of fuel on board. According my calculations that puts us at 2000 lbs. gross and at a CG of 13.7" Since the CG range is 10.5" to 22.5" we are well forward in the CG range. I did all of the flying and Lee did all of the video taping and calling out airspeeds, turns, etc.
Here's what we learned today.
1. The Bearhawk can be spun without a snap entry, it just takes a bit of patience.
2. The airplane stalls with Lee and I aboard and no flaps at about 50 MPH IAS.
3. A definite buffet (shaking) can be felt during all stalls and spins.
4. Once fully developed after about 1 1/2 turns, the airplane wraps up real fast and the nose is nearly vertical (straight down).
5. Reviewing the video over and over, I count that the turn rate of the spins after the first 1 1/2 turns is very fast, about 200 degrees per second and the nose appears to be straight down, pivoting on a point.
Here is the video showing only 2 of our numerous spins we did today. This one shows a2 turn spin and a 3 turn spin. You will see the 4-lane divided highway directly below us as a reference to how fast the airplane is spinning. The second one shows it better. We have not reached a definite conclusion yet as to forward CG spins but what appears to be happening is that the airplane is not staying fully stalled past the first 1 1/2 turn. We believe that one wing is stalled and the other one is flying, thereby creating an accelerated spin.
The airspeed indicator went to about 80 mph after the 2nd turn and by the time I recovered from the spin we were at 125 MPH. A 2 turn spin resulted in a 1,000 foot loss of altitude and 3 turns was 2,000 feet. The next time we go up, we want to rig a second camera that shows the airspeed indicator.
BTW - The Dynon D100 went into "gray" mode and had to reset itself after the 3 turn spin that you see in the video.
While we haven't reached a conclusion yet, we believe that my Bearhawk will need to be limited to 1 turn spins at the forward CG location. We suspect that this airplane will have much better spin characteristics at a more aft CG. We plan to load it to about a middle CG location soon to start testing that. I will report more then. Here is the video (it's best to right mouse click on the link then save it to your desktop and play it from there)
spins3.mpg (16mb)
On the second spin on the video, you can hear Lee call "recovery" twice. On the first time he calls it, I applied full opposite rudder but kept the control stick buried back against the stop. It took a full 1/2 to 3/4 turn for the airplane to quit spinning doing it that way. I later tried applying opposite rudder and forward stick simultaneously and found the recovery to be almost instant.
Come
back later for more updates to the webpage. This page last updated on May
30, 2009
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