|Sep 24, 2010, 01:28 PM|
Maiden ends in disaster
Conditions were good for the maiden on Wednesday afternoon so after a warm-up flight in the Extra I put the charged battery into the F-5 and set about going on a maiden.
AUW was 41 oz, I had set cg limits between 700 and 720mm from the nose, and this flight was towards the forward limit (700-710mm). Flight control check was good but in hindsight I realize I had never measured actual travels.
I set dual rates with some expo on the low rate, pulled out on the runway and put the coals to it, and it took off, leisurely. The ship was slightly nose heavy and seemed to be getting a slight roll with pitch input which I attribute to what must have been slightly assymetric deployment of the independent elevators. I felt the pushrods from the elevators to the servos were too long and soft, and will probably go up a guage or two on the next plane.
As I climbed away from the ground it seemed a bit draggy because I had a flap mix with the gear, so I tucked it all up and then she flew a little cleaner but I lost orientation, not a little, completely. I had some altitude so I didn't panic, and I put in up elevator and then a roll to the right, figured out where it was pointed, and put some power back in to climb up a little more. It took several dangerous turns and pitch ups to regain confidence in orientation. I thought I might lose it into the bay.
Because I had totally lost orientation (never happened to me before), I was a wreck - my hands were literally shaking and I was almost nauseous. I focused again on flying the plane. It tracked very straight in terms of roll and yaw (no trim required at all), but it was requiring constant pitch inputs. I would almost call it slightly pitch divergent, it was not completely predictable and this was very unfamiliar territory for me. Although I flew my Extra tail heavy on its' maiden, it was nowhere near as challenging to fly as the F-5 - the jet was a real handful.
The plane took more power for level flight or climbing than I expected based on video of stock airframes, I would estimate 60% or more to achieve any kind of climb rate, and overall climb performance seemed anemic. Speed was difficult to estimate because I had let it get quite a way away after I lost oreintation.
I do not possess a watt meter yet, so I cannot say what amount of power it was actually developing. This will be remedied ASAP. Regardless, I was not really using enough power to make it easier to fly in hindsight.
I took out the dual rate with expo at this point in pitch and it got a little better. I had set travel on pitch and roll to 80% with 25% expo for low, and full travel no expo for high.
At this time I corrected the nose heavy with some trim (1/4 of the available clicks), and turned back towards the runway, made one pass overhead and a right turn, then headed back out away from the runway. The white bottom was barely enough contrast to my surprise. It remained an effort to keep orientation.
My customized T-28 is gray on top and white on bottom and I never had orientation issues with it. I chalk this difficulty with the F-5 up to adjusting to the shape.
As I was making my way around to come back to runway heading it started to become a real handful, pitched straight up to the vertical, stalled, pointed straight down, and went in from about 100 feet.
The crash was actually beautifully spectacular and happened in slow motion from my perspective. After the pitch up, the only command the plane appeared to respond to was to remove power from the fan when it was obvious she was going straight in. Nothing in pitch or roll.
I was immediately heartbroken because I have never totalled a plane, and never on maiden. Seriously, in over 400 flights and 17 months of RC I have never had a crash like that.
When I made the walk of shame, I found the plane essentially as I had imagined after seeing the pieces of EPS blast 5 to 10 feet into the air after impact. The crash site was mostly concentrated in a 3x3 foot square, with one wing about 20 feet away. The ESC was beeping when I got there (battery checks OK, 3.84V per cell after about 2.5 minutes of mixed throttle flying).
To my surprise, not only where there many, many pieces of my plane, there were clearly parts from two other planes underneath it, DIRECTLY underneath it. I unplugged the LiPo, retrieved a big trash bag, and collected the carcass.
The airframe is a total loss, but the fan spins freely and all of the servos, ESC and main gear retracts appear to be fine. Not sure about the AR6200 yet, and I cannot bear to open the trash bag right now - of course, it is a clear bag, so the remains are staring me in the face even as I type this.
Debriefing with some of the old hats at the field they commented on the difficult color and then wondered why I flew through the 'dead zone'. I learned that the dead zone claims planes from 72 mHz as well as 2.4 gHz, inconsistently. Total loss of control, and no recovery. This explains the other plane parts I was sifting through and makes the pain of the loss subside a little. If I didn't dumbthumb it in, then I will try again.
Some lessons learned:
- Even though the color scheme appeared to have more than enough contrast when on the ground (it looked damn good on the ground IMO) it was not enough in the air and this made me nervous - in hindsight, before I fly this planes' replacement (oh yes, there will be a replacement), I will spend some more time taxiing around to get used to the sight picture at different orienations - also, I will paint the nose black and am currently favoring a total repaint to an Aggressor scheme with WAY more contrast, probably the blue Flogger scheme that the MCAS Yuma birds wear and that the NAS Miramar birds used to fly - I love the gray ghost scheme, I really do, but it contributed to issues of confidence
- I took off on low rates because I was concerned about overcontrolling close to the ground - will never do that again, I could have toned down the control after getting safe distance up and under control
- The problem with orientation and slow pitch response right off the bat shook my confidence and it never fully recovered during the flight - as I was trying to get a feel for the ship I was already dreading bringing it in for a landing - bad mental attitude leads to mistakes
- I had heard about this deadzone, and in fact my Extra and Trojan have both come back from flights with the LOS flasher indicating a brownout of some sort - in benign airplanes like those two, this is no big deal - in a brand new plane, on first flight, that was still not fully trimmed out and flying well, it was fatal - I should have kept the plane in closer and not let it get so far downrange
I will order a replacement tomorrow - probably the Swiss version for ease of painting later. I will fly it without the flap mod (or weight) to get used to flying it in the stock condition unless my Turnigy 2836 shows up before the airframe. This will also help me get used to orientation while flying and its' overall characterstics.
Overall, very sad about the loss of the plane, especially since I had put so much effort into personalizing it before the maiden. Next time the plane will be sorted before I customize, which is what I did with the T-28 and the Extra - I let my confidence get the best of me and that coupled with some less than optimal decisions and a brownout/lockout were fatal to the plane.
I do believe that I had perhaps a 50-50 chance of successfully landing the plane based on how it was flying and how I was flying it - I was that shaky.
I look forward to the replacement and getting comfortable with the plane - there will be no assumptions made with #2. I do believe that once dialed in this will be a great flyer, especially with more power.
Here are precious few photos:
Fired up and ready to hit the ground
On the roll
Sorry, Defense Department regulations prevent release of photos of the crash site pending notification of next of kin.
I will be purchasing a replacement in the next few days and will fly it stock first and getting used to the stock performance before customizing the plane, like I did with my PZ T-28 and my PZ Extra 300.
A real bummer but a learning experience. I do look forward to getting the replacement and getting it dialed in since all reports are that the F-5E is a great flyer.
In replaying the flight in my mind over the past hours I now believe I was flying extremely cautiously, too much so in my estimation. That overly careful approach, coupled with a previously unflown combination of reduced travel and expo on low rates led to letting the plane get further away on the turn out from takeoff and almost led to loss of the plane right there due to loss of orientation.
If gray Rx Ready is all they have, I will do it again, and will make the bottom white application more complete for more contrast - it honestly could have taken another coat or two for complete coverage.
Regardless, I will fly it gear down and stay close-in for the first flight, and will not hack in the flap mod until I am comfortable with flying the plane and am ready for the full monty customization which will include lights and the Hyperdyne colorchanging afterburner kit along with the upgraded motor and ESC and BEC.
I am taking it better than I thought I would. Especially since I am rebuilding my PZ T-28 and only have my PZ Extra 300 to fly for now.
|Sep 24, 2010, 03:50 PM|
Sorry about the loss at maiden. I know exactly how you felt at @ loss of orientation, shake like a high school girl at a frat party! Wish I could control that better my self. But flying a new plane is almost an addiction to me and the rush you get upon a sucsessful landing makes it all worth while, don't you agree? Let us know how the next one goes. I say keep the flap addition, might prove helpful @ landing.
|Sep 24, 2010, 05:32 PM|
Sorry to see that John. Man, that sucks. We all know how you feel. The jets seem to be easiest to get into that disorientation phase due to the scale color scheme like you said and to me, the narrow wing span etc... You have a great attitude though, I am sure you'll be fine with #2. First think I did after I crashed my P47 was order a new one. I will maiden that later today......I HOPE
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