Posts: 661
Joined: 7/10/2003 From: Indio,
CA, USA Status: offline
Maiden day for me tomorrow too....good luck with yours TXKflier....tomorrows forecast here is high of 99 ...2 mph breeze right down the runway I should have a video up tomorrow eve...
Posts: 661
Joined: 7/10/2003 From: Indio,
CA, USA Status: offline
Maiden flight was successful,...however, was cut short because the one-way air valve decided it wanted to be a two-way valve,...lost air pressure and the gear dropped. Sorry the video isn't all that great,..it was hard to keep the plane in the view finder. http://home.dc.rr.com/maurie/F18%20Maiden.wmv
Posts: 53
Joined: 9/13/2003 From: Sumner,
IL, USA Status: offline
Very nice flight for the first one Crash!! Keep it up. What do you think of the roll rate at the recommended cermark low rate settings? I think they are quite fast. I have not attempted a high rate roll yet for fear that the wings will be thrown!! Motor sounds good as well.
Posts: 661
Joined: 7/10/2003 From: Indio,
CA, USA Status: offline
Hi virtual
I haven't flown the plane yet,....I had one of the more experienced pilots at the field do the maiden,...as I'm the only guy that does any videoing,and I wanted to get the maiden flight on video.He only did one roll,....and I wasn't zoomed in at the time,...but he said it was extremely fast. He didn't try it on high rates, as the flight was cut short. I put 20% expo on the low rates and 40 on the high. I doubt if I'll ever hit the high rates switch tho. I'll order a new one way valve tomorrow,...suggestions?.....Robart?
Posts: 53
Joined: 9/13/2003 From: Sumner,
IL, USA Status: offline
Hey Crash, glad all went well. I haven't had any problems with the one way valve on mine. Maybe you should try Cermark and see if they will warrnty the vavle. If they will replace it then why spend your money? If they won't then I believe you can get one from Tower Hobbiescfor a reasonable price. I would go with Robart or Century Jet. I have both and no problems with either.
Posts: 63
Joined: 1/24/2006 From: Texarkana,
TX, USA Status: offline
Well, the weatherman missed the wind forecast a little bit. The wind was about 15 mph at about a 20 to 30 degree angle across the runway from the right. However, it was fairly steady.
The maiden flight went pretty well. I raised the gear on takeoff and flew around for what seemed like 10 minutes. I made a few approaches to check the low speed handling. Then I did a touch and go. I don't know if it was the wind or the plane, but my F-18 dropped like a rock and was difficult to keep from touching down too hard. The nose would get pretty high and the plane would sink pretty fast, but there was no sign of tip stall. I imagine I should have kept a little more power on it.
For the first flight, I had it balanced at about 6" from the root leading edge. When I rolled it inverted, it took an awful lot of down elevator to fly level. So, before the 2nd flight I added weight to the tail. This moved the C/G to the specified 7" from the root L/E. I refueled, cranked up, and headed out for flight #2.
As I climbed out after takeoff, the engine sounded like it might have sagged. So I throttled back a little, turned downwind, came around, and landed. I opened the needle a bit, checked the top end, and headed back out. On this takeoff run, the engine was a little too rich and I was having trouble keeping it straight. It drifted off the right edge of the runway and as I throttled back, it zigged back to the left, hit the edge of the asphalt, and jumped into the air. The airspeed was low and the nose was getting higher. I opened the throttle as I tried to lower the nose, hoping I'd be able to set it down without destroying it. However, as the engined revved up, I realized that the edge of the runway had shattered the blades on the Zinger wood prop. I had no choice but to throttle back and let it do whatever it was going to do. It was now about 10 feet high with the nose straight up and zero airspeed. It suddenly did a stall turn to the left and came straight down, hitting the asphalt runway squarely on the spinner. We could see the fuselage buckle from the engine back to the wing L/E. Then it fell backwards, coming to rest on the landing gear with the fuel tank and engine laying on pavement. Amazingly, the only airframe damage other than the shattered nose is a tiny ding in one wingtip.
It will fly again... but with more horsepower. The new OS .61 FX I had in it is marginal for this plane. I have a Jett .90L, but I don't want to feed it. I may try a Magnum .91 XLS in it next time..
< Message edited by TXKflier -- 10/8/2007 6:03:57 AM >
Posts: 63
Joined: 1/24/2006 From: Texarkana,
TX, USA Status: offline
Then I'll remove the tape, sand, fill, sand, prime, sand, and paint it..
Did you notice the hardware on my elevator pushrods and how I drilled and tapped the arms for setscrews? I've never liked metal clevises on metal arms, even after the arrival of FM radios. And, I didn't trust the gripping power of the clamp on Cermark's arms. I didn't want them slipping on the flying stab shafts.
I also balanced my horizontal stabs. I set up my Dubro prop balancer in the over/under mode and added weight at the root L/E until they sat level. It took about 0.65 ounce to balance each one. For weights, I cut two pieces of 5/16" all-thread about 2" long and made a slot in one end of them using a hacksaw. I drilled about a 9/32" hole in the stab root just behind and parallel to the leading edge. I mixed up a little 5 minute epoxy and screwed them into the stabs until the ends were just below the root surface. It seems to me that 1.3 ounces is a small price to pay to know that my horizontal stabs won't be trying to fly through the air backwards.
Yes, I've read everything I could find on RCU about balancing control surfaces and saw where many folks don't think flying stabs need to be balanced. It's my personal belief that every individual flying surface that could possibly come off an airplane must have its C/G at or in front of its center of pressure. Visualize an aileron that has been removed from the back of a wing. By itself, it kinda resembles a wing, doesn't it? So does a rudder or an elevator. They each have their own center of pressure and center of gravity. What happens if the C/G is behind the center of pressure? They'll want to swap ends when travelling thru the air. An improperly balanced control surface may never flutter, but it would like to. The only thing stopping it from doing so is a tight linkage. And that's just not good enough..
Posts: 8
Joined: 6/2/2005 From: manasquan,
NJ, USA Status: offline
Hey TXKflier sorry to see your plane damaged like that, I had some minor damage to the nose that I was going to fix in the same way. I am contemplating if I should try to paint it, do you have matching paint or are you going to repaint the entire plane. I e-mailed Cermark to ask for touch paint but have not gotten a response. Please post some picture of the repair. Good luck.
The jury is still out on whether or not stabs should be mass balanced. On an All Flying Tail (AFT), having the cg behind the center of pressure is bad, however, when the pressure is behind the cg, the stab will always want to weather vane into the wind, much like a flag. This is good! This greatly relieves the stress on the servo setup when the plane is at speed, and of course becomes a little greater as the speed comes down. The real F18 does not have balanced stabs and drop like bricks once the hydrualic pressure comes off them.
Personnaly, I have never balanced an AFT and have never had any problems with them. It is too easy to install digital servos that are overkill for the required torque. Hitec 5645's on 6v are more than plenty to fly this plane. The mechanical setup should always favour the mechanical advantage side, ie: in on the servo horn, out on the control surface. Of course, if tail weight is needed, why not add it to some place that will do a little good, like the stabs? I just would be cautious as to how much you add. You always want them to drop aft, rather than have them closer to neutral.
Spar
_____________________________
Oh great are the days my landings = my take-offs....! Revver Bro #158
Posts: 355
Joined: 11/8/2003 From: vernon,
NJ, USA Status: offline
Don't know what all the fuss is about?I have the F-16 with over 400 flights and no problems with the Cermark controll linkages no slipping or problems.Blancing the aft.Why?I am over 50 flights with the F-18,The roll rate is great about 2-3 on the stick movment It is a quick roll rate I love it.It lands great and flys great.It has been radared at 118 but there is more speed in it.I feel it is quicker than the F-16 which has been clocked at 126.
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All Forums >> RC Airplanes >> Extreme Speed Prop Planes >> RE: CERMARK F-18 HORNET, BUILT IT BETTER, STRONGER, AND FASTER! 
RE: CERMARK F-18 HORNET, BUILT IT BETTER, STRONGER, AN... - 
...2 mph breeze right down the runway 
I should have a 
