Edge 540 2nd flight almost last
 

Finally got to maiden my Edge this weekend and it was interesting to say the least. This being my first gas plane I tried to research the subject through this and other forums pretty intently. Paid a lot of attention to every post I saw on RF interference, both external and on board. To give you just a brief background, I'm a mechanical engineer (23 years experience) that has worked with a bunch of EE's and antenna geeks for the last six or seven years. I actually build and tune antennas as part of my job. Ceramic patch, F's, loop, dipole, etc.. So, I have a pretty good understanding of things in the RF world albeit without any formal training. On to the maiden flight.

First flight was the usual maiden - get her up, get her high, trim her out, with a bit more pucker factor than usual, it being the biggest and most expensive plane for me to date. I did a range check before the flight and all appeared well. TX antenna collapsed, engine running, paced off more than 100 feet, no problems. No sign of any weirdness standing by the plane either. In the air the plane seemed a little twitchy to me, which was surprising (I'd figured it would seem very stable compared to the 40 and 60 size planes I'm used to) but, I attributed this to my nerves and inexperience with the plane. Just as I was landing the right wing dipped and I sort of pancaked it in. Bent one side of the landing gear but no structural damage. I pulled the canopy and checked everything inside, straightened the gear, refueled and got ready for flight number two. I figured I must have stalled it on the landing. Told the wife that I would evidently need to keep the speed up a bit more.

On the second flight I was feeling more comfortable and actually did a few rolls, but nothing fancy, just trying to get the feel for the plane. On a southerly line over some heavy woods I started to bank left to bring it back when it very suddenly rolled right into knife edge flight. The little "Oh sh--!" light went off in my head, but I leveled it out, only to have it do the same thing again. By now the plane is getting kinda small and low. I fought it back up and around to the left, convinced for a couple of minutes that I was headed for the Gulf of Mexico. It seemed like a long time, but was probably only 3 to 5 minutes that I fought the thing back to the field. Flipped everything off high rates, brought the throttle trim down and lined up for landing. Five foot off the ground it rolled right again and dorked in. Engine snapped off the with the front of the engine box, cowl looks like it got beat on, landing gear pancaked flat, cowl tabs all broken. Not a happy day, but glad to get it back at all. Minor damage to fuse, wing unscathed.

Having had time to think about it, I realize that in every case of being "hit" the result was a roll to the right. The twitchiness I noticed on the first flight was probably RF hits, more so than my nerves. I pulled out the scanner and checked immediately after the landing/crash and there was nothing external that it could detect. The interference did not seem to have anything to do with distance either. So, I'm almost certain it is on board interfence. The receiver is over 14 inches from the ignition module, all servo leads are twisted, the choke and throttle pushrods are plastic tubes inside of plastic guides. The motor is an almost brand new DA50. Receiver is Futaba, PCM, eight channel (wrapped in foam) and it's never given me any trouble in the past. In fact, I've never had any kind of RF hit, though a couple of people at our field have. I've done everything I can think of to eliminate on board interference, but obviously I need to do something else.

My flying buddy has been building a WH Extra and he's a whee bit puckered about his maiden flight now. He is an electrical engineer and works on the same project I do, so we both understand the RF world. We are both fairly baffled. The only thing I can think of to try is to remove the PCM receiver, replace with a similar PPM and range check again (once the repairs are complete, which will take a while). Thing is, I thought PCM was the best for limiting on board interference and that if it got a bad data stream it would just lock and do nothing. This twitched right, over and over, as if the ailerons got a sudden brief input. No other channels seemed to be affected. Servos are JR8611 on rudder and HiTech 5645's on aileron and elevator. TX is Futaba 7CAP. Two 1650 mAh NiMH's for receiver, charged the day before the flight. Engine ran fine, spark cable and boot are undamaged. I don't think we are missing anything obvious here, but we are missing something. It was definately worse on the second flight, if that provides any clue.

Any thoughts?
Thanks,
Bill Gavin

RE: Edge 540 2nd flight almost last
 

PUll the PCM and put in an FM and range check the combo. If your clean on the ground with the engine running then your most likely going to be clean in the air IME. Using a PCM right off the bat is a great way to mask a problem that will bite you real quick. I am continually amazed that guys will buy a PCM rec and then not that is seems to range check good on the ground. If you are having interferance then the PCM will not jitter it will simply hold the last input till the interferance subsides which can fool you during a range check on a new airplane.

From all that I read it sounds to me like you have too much elevator throw and are possibly a bit too far to the aft end of the CG range. These planes will slow down pretty quickly when you pull the power off or bank them hard with the throttle at idle. I have found that for low rates these planes seem to like about 10 degrees of throw MAX, 12 degrees can work if your balance is back a bit more but if your on the nose heavy end of the range the plane will want to snap on you. I have found that more than 10 degrees of throw at moderate to full throttle will result in a pretty wild ride if your heavy on the elevator. The flying surfaces on these models are big and airfoiled for a reason, hence they are VERY effective. These are not .40 sized models, they fly more like real airplanes and as such require a bit of adjustment of one's habits and skills.

The dropping of a wing could likely be an indication that the right side is heavier than the left. To check if it is take the plane up high and throttle back, point the nose sraight down and let her dive and then pull hard. If the plane has a heavy side it will drop that wing every time. Add some stick on weights to the tip of the light wing and do the test again till the wings pull level.

RE: Edge 540 2nd flight almost last
 

You're on the right track with your comment about switching to PPM and range checking again once it's rebuilt. PCM is great, and I won't fly anything else in my big gassers....but for an initial ground range-check, PPM is really the best choice. PPM will allow you to "see" any hits and visually show you when you are at the limit by jittering or moving control surfaces. PCM will ignore any bad packets and the surfaces will hold perfectly still even with the TX off. This makes it hard to determine when you've hit your ground range limit.

That said....there is something severly wrong if you were getting frequent "hits" during flight with a PCM rx. If the signal really was that bad....then the plane should have gone into "hold" if the interference was intermittent, and into full lock-out if the interference lasted for a considerable length of time.

Since you indicate the plane rolled consistently to the right during each "hit", then my first suggestion would be to check your TX's fail-safe settings. On a plane this size, I assume you're mixing the ailerons together using the radio (ie, on Futaba systems, ch1 is mixed with ch6). It sounds to me like the fail-safe setting for one of these channels is set to go to some position other than neutral.

This may not be your problem....but it's a place to start.

RE: Edge 540 2nd flight almost last
 

In reply to Shogun.

Have no idea why you think my CG is too far aft - it is at 5 inches. The receiver did not lock out as you would expect with PCM - it consistently twitched right. Elevator throws are set per the WH manual. Plane flew fine. I've flown tail heavy planes before and this one isn't. What I thought was a wing dropping, I'm now convinced was a hit on the aileron channel. Range check consisted of making sure from a distance with the engine running that the control surfaces did what I told them to do and nothing else. Not just looking for jittery movements which I know better than to expect with PCM. Engine was actually broken in on test stand using a PPM receiver for control. No interference then, but not all channels used.

In reply to jmiracle.

I'll check the failsafe settings on the TX. Have never messed with them before. Thing is, if it was "failsafeing" to some position other than neutral I would have thought I'd see that on the ground. Still, worth a shot. I am mixing channel 1 and 6 just as you said.

I would have expected ignition interfence to be more random in its effect. As far as I can tell only the ailerons were affected. Maybe this supports the theory of a failsafe setting being in some weird position. Perhaps other channels were affected, but went to neutral and thus I didn't notice them. Still baffled as to why I'm getting the interference though.

Thanks for the suggestion

RE: Edge 540 2nd flight almost last
 

This may or may not help you. I had a similar problem recently at a fly in. My plane wanated to roll to the right. I actually managed to save my plane and get it down in one piece. The cause.... Nothing to do with the plane. I had some one else turn on on my frequency. Every time I "lost" the plane it rolled to the right. Everyone started yelling check radios when this started to happen to my plane. The guy turned off and I was able to get my plane down safe. The only people at fault where the radio impound folks.

My plane was a will flown and tested gasser and had never had any of these type problems so it was easy to deduce another radio was at fault when things started to go bad.

RE: Edge 540 2nd flight almost last
 

I'm with Ken, this is sounding less like interference that something else. His idea of channel conflict is one idea, I was thinking that there might be an aileron servo that's twitching or jumping. That can be caused by the servo itself or by a loose connection, bad servo extension, bad channel in the rx, etc.

Raplacing the rx is a good idea to test things, but I've never seen a receiver act that way.

TF

RE: Edge 540 2nd flight almost last
 

Ok Ive had 2 glitches on my Edge..the first one was due to a faulty elevator extension..Jiggle all your extensions and actually tap on t them where they meet..thats how I found my extension problem...The second was with the landing gear bolts..I must have forgotten to loctite the bolts..after about 100 flights I started to get minor glitches..it would only be for a second..the throttle would goto idle and the controls would goto neutral..at first I thought it was outside interference then it started happening more and more..I checked everything and then noticed one of the bolts looked wierd..all 4 of them were loose! Now I used lock washers and loctite..just something else to check..My guess is its a bad extension...good luck...

RE: Edge 540 2nd flight almost last
 

.

RE: Edge 540 2nd flight almost last
 

I will check the extensions. Don't think that's it - I used shrink wrap where they are joined, but you never know. I'd love to think it was something external, but it's just too easy to use that excuse. In 75% of "outside interference" cases I have seen, it turned out to be a bad battery connection or receiver crystal falling out. I have seen a few real ones though, on certain frequencies. Just never happened to me. There are a couple of cell towers near where we fly, and once I actually picked up music on my scanner in the 72 Meg band. Distorted, but you could recognize the tune. Just never saw anything that lasted this long and consistently repeated the same action. I saw a reference somewhere about taking a ground wire from the spark plug boot to the motor. Thought that with the DA supplied ignition, shielded cable grounded through the boot that that wasn't necessary? The idea that maybe one of the aileron channels is set to a weird failsafe is intriguing. I'll check that tonight. Anyway, thanks for the suggestions. I will post whatever I figure out.

Bill

RE: Edge 540 2nd flight almost last
 

I did as well..they were plugged in tight but I guess one of the prongs were loose or something cause when I held it and tapped on where they meet my elevator servo jumped like it was on fire!!:)

Also Ive read to check the spark plug for cracks and make sure the igniton wire isnt frayed..

RE: Edge 540 2nd flight almost last
 

To me It's sounding less like a RF problem and more like a problem servo.
Swap out the two Ail. servos with each other and recheck.
See if the problem moved with the servo.
If Not, check with another Rx and servo Ext.

RE: Edge 540 2nd flight almost last
 

And THIS is the reason that failsafe was almost outlawed in England. For some reason, the manufacturers all set up the fail safe to default to hold the last position. The problem with this is that you can blip the throttle on the ground, the radio goes into failsafe at that moment and the plane will then go where it is pointed at full throttle! This is very dangerous and NEEDS to be addressed.

When you are using a PCM receiver, make sure that you set the failsafe properly. There are various theories as to what is best to do with the controls, and I'll leave that to someone else's opinions, but at least set the throttle to go to idle in the event of failsafe!!! When you are doing a range check, I also find it helpful to set the elevators to go to full up when it goes into failsafe, as that gives me a good indication that I've reached the limit on the ground. In this way, you will know for sure if the radio has gone into failsafe during a range check. Of course, make sure you set the elevators to do what you REALLY want them to do when you are done the range check.

Having said this, I don't think you had an interference situation in this case. It sounds more like something wrong with a servo, extension, or something along those lines

Jim

RE: Edge 540 2nd flight almost last
 

The Edge is a very stable model, when set up and trimmed correctly, almost too stable for my taste at times but heck it's and Edge not a Cap. The twitchyness could be attributed to an excess of low rate elevator throw, these planes have a powerful elevator and it can be extrmemely sensitive, especially if the balance is rearward. I almost doinked mine on the maiden with the balance set at a bit past 5 inches because it would not drop the nose at that balance point when the power was pulled back. These airplanes will slow down very quickly and stall, dropping a wing, because of that big prop up front that creates much more drag than what most guys, who are used to flying smaller planes, are used too.

I found that my Edge likes no more than 10 degrees of throw on the elevators with the balance at 5.250, any more and she will depart. If the airspeed is up it can happen pretty quickly. In a panick situation most will tend to yank hard on the elevator, or worse, pin it back and hold it there which compounds the problem.

I set mine up per the manual as well and with the recommended 15 degrees it was simply too much. I like to set my airplanes up so that I know that no matter what, a full pull will not result in a departure at any speed. In my case it turned out to be 10 degrees, not the recommended 15 degrees. Changing the balance will alter this so it will change with forward of aft movement of the CG. I observed that with the recommended 15 degrees my model would depart at the bottom of loops and in tightly banked turns without fail. With the lower throw it just grooves right through every maneuver I throw at it.

I have no idea what your high rates were set too but if they were 3D rates(45 degrees or more) that could very well be the source of the twitchiness you mentioned earlier. In general the only time you will be using large throws would be at very low airspeeds. Bear in mind that I am speaking in generalities here because I have no idea how you had the high rate throws set up on your model.

With a forward CG the Edge will drop the nose and head for the ground which is pretty easy to observe. The landings can be a bit hot, resulting in bouncy landings because the plane is hard to slow down to the point where the wing stops flying.

With a more aft CG the Edge will maintain nose level or it will hold the attitude it's in until you alter it with pitch control. As I mentioned above the plane has a big prop and will bleed speed VERY quickly. A stall can result very quickly if your not on top of this! I like to leave a couple of clicks of throttle in until over the landing threshold and then cut the throttle and she will settle down very softly on the main gear, sometimes a pretty 3 pointer can be had if you time the elevator input just right.

I have a flying friend at our club that maidened his Edge last week. His is a pretty typical set up with a DA 50/8611 all around. The model is balanced around the 5 inch mark and flies a lot like mine does. He's a pretty experienced pilot and even he got caught off guard and almost rolled his into the corn at the end of the runway when he got it too slow. He also felt that the 10 degrees of throw I initially set his plane up with was too little so he bumped it up in the programming in his 9C. After the change he kept complaining that the plane was hard to fly in a smooth manner and seemed twitchy. I backed the throws down and he flew it again, he's planning on leaving the low rate throw right where it is and couldn't believe how much of a difference that small change made.

I'm not trying to be critical here, I just thought it was interesting that there were quite a few parallels between what my friend experienced last week and what you described in your initial post.

RE: Edge 540 2nd flight almost last
 

Checked failsafe settings last night. All channels are set to normal except throttle which is set in FS to idle. When set to normal the reciever should hold the last valid position if it gets a bad data stream. Pulled, tugged, twisted and shook on the aileron connections while working the stick back and forth - couldn't get it to misbehave. Low and high rates are set per the WH manual with expo set around 65%. Had done a few figure eights and a couple of rolls before the problem happened and was getting comfortable, so I don't think I did something weird to stall the plane. First really severe occurence was at about mid throttle with plane on high rates. When it happened right before landing the throttle was at idle and plane was on low rates. Every twitch was to the right, without any input from me or with opposite input as in started to bank left and the plane rolled right into knife edge. No, the servos are not reversed. I would get it back to level flight, center the stick and then it would roll right. I'd never say that I couldn't have screwed up, but I've been flying 3D style planes for over a year, so I'm used to being light on the sticks. I've flown one that was so tail heavy it would stall immediately if you went to idle and I managed to land it intact. I'm going to check the rudder servo set-up tonight. I couldn't see which control surfaces were twitching, so maybe it was rudder and not aileron. Rudder is set up for some massive throws so it might cause the same thing. I've noticed that the rudder servo doesn't seem to center at the same spot every time I power up. This may be something wrong with the pull-pull set up, though it seems to operate fine with little or no slop. Short of that, I'm just going to have to put it back together and do some ground testing with the engine running to see if it is on board interference. No one else was flying so I'm very sceptical of claiming I got hit from an external source. Thanks for all the suggestions. I don't have an answer yet, but I am learning some new stuff in the process of looking.

Bill Gavin

RE: Edge 540 2nd flight almost last
 

Just something to look at.

The braided wire that goes to the spark plug metal boot, if it isn't crimped right it can cause interference issues.

RE: Edge 540 2nd flight almost last
 

Would this crimp be at the boot end of the cable? At work now so I can't look at it. One other thing - I'm using a Futaba MSA 10 Servo synchronizer to coordinate the elevator surfaces. Any reason to be concerned about that? It set up very easily and seemed to work perfectly.

Bill Gavin

RE: Edge 540 2nd flight almost last
 

Normally no. But until I read this I was thinking that you had an elevator servo glitching & causing the problem. Do you have both elevator servos running off one channel through the MSA-10? I have never heard of anyone having a problem with that device but tons of people have had problems with the "miracle Y", which when push comes to shove is really the same thing. I think I would try swapping that our & see if your symptoms don't go away. An elevator servo glitching on a plane of that type is more then capable of causing the problems you describe. Like the others, I think your problems are related to either a servo or something else in your setup, not outside RF interference.

RE: Edge 540 2nd flight almost last
 

I've never read one bad thing about the MSA 10 so I can only assume they are very reliable based on a lack of negative feedback about the product. The JR matchbox is a similar unit and has a reputation for being very reliable as well.

I still say that if you suspect ignition interferance just put a PPM reciever in the plane and see if the installation is quiet. I fly PPM in my Edge and have had no issues between it and the DA ignition. I also have my throttle and choke servos installed within 2 inches of the ignition module and the ignition battery. For pushrods I am using the same 4-40 all thread/carbon fiber tube as on the control surfaces with nylon ball links on the ends for electrical isolation. My PPM receiver is mounted right in front of the wing tube so it's not as far aft as some feel it should be. I have had no issues with this set up whatsover since the begining of last year when I first flew the model.

Modern ignition modulules are pretty quiet devices IMO and their RF output is usually so low as to be a non-issue in most installations. Now if you cut the braid on the high tension lead or have a loose connection they can get noisy, but this is easy to check for and correct. From what I have experienced a loose metal-to-metal contact, like the one JJ described above, is a much bigger interferance culprit than the ignition system itself in most cases.

Hope you get this figured out because the Edge is an awsome flier!

RE: Edge 540 2nd flight almost last
 

I am using the MSA 10 to route both elevator servos through to Channel 2. I tried mixing channels 2 and 7 for the elevator, but my CAP7 doesn't seem to support that. The manual originally indicated that it did, but the addendum sheet for that page said something like, "page such and such, cross out section such and such". They seem to be right - it doesn't work. Guess at this point all servos are possibly suspect. It seems that the only channels I can fully mix (i.e. get equal response from an input) are 1 and 6, which I am using for ailerons. I haven't been able to duplicate the failure without the engine running which leads me think there is a relationship. Might be Rf or might be vibration causing a servo glitch that I can't cause directly. We run into intermittents like this at work all the time. It is maddening. Until you can repeatly cause and observe the failure it's hard to isolate. Thanks again.

Bill Gavin

RE: Edge 540 2nd flight almost last
 

In reply to Shogun.

I will certainly do some testing with a PPM receiver once I get the pieces glued back together. However, several people have voiced the opinion that my problem doesn't sound like RF interference. I did a search on the giant scale forum and found a lot of discussion about the MSA 10. There have been some problems, but usually when someone ran four servos through one MSA 10, which I am not doing. One guy described using a servo reverser (not MSA 10)and seeing one half of his elevator lock straight up when he switched on with a freshly charged battery. Did find a post about internally reversing a servo which was very intriguing and would allow me to eliminate the MSA 10. Assuming I can get the endpoints mechanically adjusted to be the same, that would be great. Still, I want to identify the problem. Until I see the failure, change one thing and have it go away, I won't know if it is truly fixed. Some things I can't do until the plane is repaired, but in the meantime I can do some research. I've gotten a lot of good info from this thread. Thanks to all.

Bill Gavin

RE: Edge 540 2nd flight almost last
 

Hey Bill I had some thing simmular happen to me as with you I found that my elevator servo wires were rubbing on the pull & pull wires and causeing inerference seperated them and got them off the pull pull problem solved, simple

RE: Edge 540 2nd flight almost last
 

I have no idea what a Cap7 is but I assume it is some sort of Futaba? I have a 9C & also a 9Z. both of which are capable of dual elevator mixing. The easiest way being by using the ailevator funtion & just turning off the aileron portion of that mix. I know that the new Futaba 7 channel radio is pretty much a 7 channel version of the 9C. Does your radio not have a mix like that? Just asking, since if it does, it would be the easiest way to clear up the problem. Otherwise, I'm sure you can just take a available pmix, change the master & slave to aileron & aux2 & make it work. (Assuming that you do have the newer Futaba 7 channel.) I'm not trying to be condesending, just trying to help.

This is not to say the MSA 10 is the problem. I have two of them in my big Aeroworks Katana & they have never given me the first glitch but that doesn't mean they couldn't. If that doesn't turn out to be the problem I'm sure that between all of the knowledgable people on here we can find a solution, even if we have to easteregg it to death. The ppm/pcm idea is a good one if you suspect RF interference but if that were the case I would expect to see all of the servos going nuts & you would hear the engine changing pitch as the throttle glitches as well. Whatever the case, I would never fly it with the ppm reciever unless I knew the "glitch" had been found & cured.

RE: Edge 540 2nd flight almost last
 

Something I completely forgot about would be the rudder cables. Are yours crossed? If they are they could be touching due to engine vibration. Mine are straight back, not crossed, and work perfectly. It really isn't necessary to cross them with this airplane in the first place. The real key to getting the cables set up right is to get the connection points in the rudder horns exactly on the hinge line. In my case I used the Du-Bro horn assembly that came with the hardware pack and found that by using the unmodified black plastic horn extensions I wound up with a connection point that was a full 1/4 inch forward of the hinge line, not good. I wound up marking them for new pin hole locations and cutting them off with my Dremel tool, dressed them up a bit and put them on the plane. Works perfectly.

RE: Edge 540 2nd flight almost last
 

The 7 CAP doesn't have the ailevator mix like the 9 CAP and 9Z do so he's stuck havbing to use a reverser or some other method to get it to work correctly.

RE: Edge 540 2nd flight almost last
 

Bummer