-
-
Hey guys, OMG the elevator problem happened to me! But the model is OK. Let me tell you what happened.
First, I have the upgraded servos, 4-40 rods with CF tubes and HD ball links, inner holes, and I replaced the elevator horn screws with larger ones and glued them in. Everything is tight, no play, no slop, no bending, no flex.
I have installed counter-balances on the elevators.
The elevators are plugged in the the receiver bypassing the blue box. I have RF chokes on the leads from the ESCs and also the power lead from the BEC going to the receiver.
RT6250's in the mid and back positions, balance normal (not 10mm back, so I have maybe 5-6mm of up trim)
I've enjoyed flying this plane and had several flights today, everything was going perfectly. Until it wasn't!
So towards the end of the last flight of the day I was flying at a mid-range speed from left to right, not too fast, and was coming downhill wings level. It was not in a high-speed dive, just kind of flying downhill at about a 20 degree down angle.... and all of a sudden I realized that the elevators weren't responding! Just stuck in that attitude, coming straight in towards a highlight-reel crash just like in those videos. It was directly in front of me. I had that horrible feeling that something was wrong and I was trying to pull up, nothing was happening. I chopped the throttle and it responded, then I was able to pull up - it was about 10 feet off the ground and it behaved normally after that. So I came around and landed and everything was fine except for my nerves!
The loss of control lasted about 2 or 3 seconds. Not enough time for a full evaluation, it just seemed like the elevators acted like they were "stuck" like we saw in those videos. It wasn't going fast enough to be an aerodynamic problem.
So after I calmed down and started checking things out on the bench, I discovered something.
I was showing a buddy how I have the receiver in the front compartment and the satellite all the way up in the nose. So he said, "are the antennas in different planes" and I said "I don't know" and I took it out to check. The receiver is flat on the floor and the satellite was also flat on the floor (up in the nose) - and when I pulled it out the satellite wire just fell out of the satellite. In other words, the connector fell out, it wasn't plugged in securely! So the only straw that I have to grasp is that perhaps the satellite wasn't working and the receiver lost signal for a couple seconds.
And thank goodness is started working again in time for me to regain control!
Back home now, everything in good shape and I am glad that the model is ready for the next time out!
Marc flies FW & FL: AL37, MiG-29, T45,F4, A4, A10, F104 70 and 90, P38, Dauntless SBD, Corsair, B17, B24, B26 & P61, Lipp.P19, ME262, Komets, Vampire, SeaVixen, FMS Tigercat, FOX Glider & Radian XL.
Rabid Models foamies, including my 8' B17 & 9' B36... and my Mud Ducks! www.rabidmodels.comComment
-
So you chopped the throttle...which means you had control.
Need to investigate further perhaps.
dwComment
-
Wow!!!Comment
-
Whew! And my daughter-in-law thinks RC flying is just boring. Good write up. Glad you recovered.
-GGComment
-
i thought the same thing at first too, but i also cut the throttle which means I had control between the tx and rx. I know the exact pants filling feeling!
Comment
-
So, I make no representations as to the adequacy of the servos supplied with the Mig, but in the interests of tinkering I carved out some room to fit a 57g 8kg Hi-Tec.
I couldn't have imagined it would change the handling of the jet as much as it did. It will almost snap itself on the pitch axis lol. I had to dial down rates a fair bit, even with the same throws, to get a smooth flow back in the turns. It's incredible how responsive it is now, I need to relearn the plane.
Comment
-
Yes. Like this....
The flight was normal...takeoff, 3 min of flying around, drop the gear, turn to downwind, drop the flaps, and start a big wide base turn to final. Just as the plane was about lined up on final at 100 feet altitude the plane suddenly rolled hard to the left. I tried to correct with full right aileron but the plane wasn't responding. At this point 60 years of flying took over and I was just fighting to get the plane level again. At some point I realized that the plane was inverted at 50 feet and about to crash. Somehow I had a quick thought to try rolling left. The plane responded so quick it rolled 360 and was inverted again. I rolled left again and managed to get level upright and chopped the power and just fought the plane down to a pancake landing in the tall grass.
Walking to the crash I was somehow thinking that the radio had failed. But, looking at the plane I quickly saw the problem....split flaps. The right flap was extended, but the left flaps was retracted...actually a little more than normal retraction location. The damage is relatively light....broken nose cone, broken nose gear, banged up wing tips.
Replaced flap servos and blue box and no problem sinceComment
-
Hey folks I successfully did my maiden today. Got two great flights in. Definitely have to play with the elevator trim to get it right. The 1 mm down was too little. I'm probably at 3mm now and it's better. Flew at the CG marks and it was ok, but I plan to start going back mm by mm. I'm flying RT 5000 70Cs off a 400' paved runway. Put the chokes on the ESC wires and had no issues. The plane takes off and lands like a dream. It flies like a delta wing. That means the nose can drop in a steep turn. Be wary of this. Rudder can be your friend here. The ailerons were a bit on the touchy side so I dialed in 40% expo (my preference) and it was better. Advice here is sound. I made it to page 82 before I did the maiden. My club members loved it and she sounds great in the air. Got lots of questions and even the turbine guys liked it.Comment
-
Sounds like a reverse servo was installed.Fly low, fly fast, turn leftComment
-
Hello themudduck
So your writing (in red) indicates that NO the antennas are not on different planes which "can be" very problematic.
The ideal 'positioning is if the receiver antennas are in a horizontal plane the satellite antennas should be in a vertical.
This type of arrangement provides for wide crossing elliptical lobes of reception which is for minimizing signal fade and or loss.
Separation of the two should preferably be no less than 4 inches.
Having a loose wire connection is the worst case scenario as you luckily found and thus avoided a possible oh crap moment.
Best regards,Warbird Charlie
HSD Skyraider FlightLine OV-10 FMS 1400: P-40B, P-51, F4U, F6F, T-28, P-40E, Pitts, 1700 F4U & F7F, FOX glider Freewing A-6, T-33, P-51 Dynam ME-262, Waco TF Giant P-47; ESM F7F-3 LX PBJ-1 EFL CZ T-28, C-150, 1500 P-51 & FW-190Comment
-
Oh come on, lets not start with the nose heavy CG thing all over again.......
Comment
-
I had a servo in my FW F-104 that worked fine for about 3 minutes and then stopped. Unfortunately it was on the elevator. Took me 3 crashes to properly diagnose the issue, when I finally put the servos on a cycler and left it running. The behavior was quite consistent - no problems when first turned on so I didn't pick it up during the pre-flight, but a few minutes later it would quit.Comment
-
Not starting anything, just pointing this out to him as most likely he hasn't gone through the whole thread.
If everyone starts jumping on me for making a pretty obvious and proven recommendation to improve plane handling, THEN we will have a pointless debate. ;)
Droping nose on turns has very little to do with airplane planform, and very much with CG placement.Comment
-
Well, as old as it might be getting, the world just never seems to run out of pilots having completely unnecessarily bad experiences due to poor cg. It quite simply is such an overshadowing, ultimately important aspect of setting up any aircraft, rc or otherwise.Freewing A-10 turbine conversion: http://fb.me/FreewingA10TurbineConversionComment
-
-
I agree the cg feels wrong when I fly, but the plane is not unsafe or unstable. It's just more work and less enjoyable. That's why I said I'll be moving the cg back progressively over the next few flights. My personal preference is to change one thing at a time with a new aircraft to minimize confusing while making adjustments. My first few flights involved changing the elevator pitch and frankly doing the basic trim work that any new plane requires. The dropping nose is one of a few symptoms of a nose heavy aircraft. I shared to affirm the recommendations being made.Comment
Comment