Hi Jeff,

I am sorry to hear of the loss of your plane and equipment, but I am glad you are OK.

It sounds like your accident had little to do with your flying electric. The exact thing could have happened while using wet power with a throttle control and a prop too large for the planes LG on grass. At low RPM there is very little forward speed. This means that any bump in the surface will have more impact on the direction of a wheel than the inertia caused by the slow forward movement. This sounds like what happened to you. Your left (inside) wheel most likely came to a bump or fell in a hole. This was like the pilot putting the brakes on the left wheel to turn the plane HARD left in a taxi area. The light wind from the prop on the Stab/EL was enough to take some wt. off the nose gear, or hitting a bump could do this too. Now your plane is nicely balanced on just the two middle wheels, this meant that your plane REALLY wanted to rotate in the yaw axis with very little provocation at this slow forward speed. 

I have over 400 flights on my 1st ECL plane (ARF P-40), 355 of them on a rough grass field using my stooge. I have never had any problems after I did two important things to avoid the problem you had:

1. WE NEED A LONGER, STRONGER, STEEPER ANGLE LG FOR ECL ON GRASS.

Almost ALL CL planes are designed for wet engines that use small 10" props. In ECL we typically use 12" to 13" props. On grass this means we MUST use longer LG, unless your grass field is like a putting green. I am a CL retread and when I started flying contests a few years ago I was shocked at how many nose-overs there were on TO and landings on grass because guys were using LGs and wheels that were designed, both in length and angle, for pavement. If the grass field was a little rough the problem got to be much worse.

I immediately made up a new LG that was about 1 1/2" longer and raked forward so the wheels were ahead of the LE in flight. I also went up 1/2" in wheel size. I also went up from the std. 1/8" dia. wire to 5/32" wire LG. This, with #2 below, solved ALL TO and Landing problems. My plane does not even come close to a nose-over, and I fly off a rough grass soccer field. BTW: I think some of these LG mods would be helpful for wet system 4C larger prop using planes flying off grass fields.

With your tri-gear setup on grass all the LG problems are amplified. The pathfinder is an excellent plane, but on grass it needs more power for a straight TO than a taildragger does. Due to a tri-gears configuration it is very prone to being easily turned on a grass field, especially at low speeds. There is a reason we fly FS taildraggers off grass and not TGs. I have flown FS TGs off rough grass and it is dicy at best, it needs a lot of power before brake release.  This leads us to the next issue.

2. WE MUST WAIT FOR HIGHER RPM BEFORE RELEASE ON GRASS!

 Please keep in mind that lift goes up exponentially with an increase in speed. Roughly: double your speed your lift goes up 4 times as much. This means that when our props are at a low RPM they produce very little lift (thrust). We have to WAIT until we are very near max RPM before releasing our stooge pin off grass. With close attention we can learn in a few TOs what the correct  min. RPM for a smooth safe TO is by listening to the motor spool up. When I came back to CL I backed into this TO RPM by starting at FULL RPM with each successive flight having less until I felt a little uncomfortable then went back to the flight before RPM release. After about 20 flights you can tell by sound when the right time to release came for the grass conditions of the day. ;-) ..... If you are ever in doubt, or an inexperienced pilot, I recommend letting the motor get to full RPM before launch off grass, or on any surface that can catch one wheel to turn the plane.

This is the same for ECL or wet power systems with a throttle on grass.

WE NEED TO ADDRESS BOTH ISSUES ABOVE

Both of these are important issues. If we have a nose-over, or other issue that stops the prop, we will overheat our systems and some part (ESC, motor, batt.) will be harmed. The solution is to do all we can to avoid prop strikes.

Your pathfinder should have no problems if you just put on larger wheels and try #2 above. I really like the pathfinder, I think it is one of the best flying profile planes available. If I had one that I was going to fly off grass with, I would convert it to a tail dragger using one of the profile LG from Randy. I really like Tail draggers, FS or models ;-)

Regards, 

Hi Jeff,

I beg to differ with your statement..

""".because at the Detroit contest a couple weeks ago every electric ship there had trouble getting airborn off the mowed grass"""

Using the word EVERY can  unfortunately give some people negative feelings about electrics being difficult to fly off of grass. At the Siganal Seekers, over the two day event,  I flew 6 flights in 4 different events..placing in 3 of them using electrics.  I  did had a  problem with just ONE takeoff   (a  sudden wind shift) which was quickly remedied  by moving the planes  location  takeoff more into the wind.  Granted, the grass was a little long and in addition was wet, which caused both, many gassers as well as some other electrics to have problems accelerating. The trick for flying off of grass, which has been explained by many  others above is to NOT launch until the motor is at FULL rpm.  I'm sure that  practice will greatly help minimize future potential damage. 

Good luck in the future.

best,
Rick Sawicki 

As far as I know, there is a current overlimit circuit in the castle ESC, if it is not dissabled in the setup, it should prevent this very thing from happening. I ahve nosed my EP-40 over, and the prop was stalled by the grass, the EXC shut off before any damage was done, ( excepting my pride) Glow setups struggle just the same getting off grass as do electrics. You need, longer gear, positioned forward, more power than on asphalt, these same things apply to a glow setup, the only difference is when you drag the prop on a glow motor through the grass the engine gets stalled and quits kaput! To me, and my program, there are more disadvantages than advantages, to trying to take off at partial power. control response and your ability to make a good take off is enhanced by having full power at the time of release. Learn how to fly the airplane On the ground, and control the take off attitude. full power allows more airflow over the controls even with less airspeed. It also allows you to hop it off the ground an inch or so to get clear of the grass drag.. Just my experience and opinions, your mileage may vary

I think everyone at the Signal Seekers meet will agree that the grass was a mess. It was very thick and everyone had trouble with it. Power per se was not the issue. I watched Bob McDonalds USA-1 powered iwth a piped PA .75 nose over 4 straight times attempting to takeoff. The prop finally plowed a path thru the grass that let it take off. Literally it was a trench about 3 or 4 feet long dug a good inch deep into the stuff. It was for those not there a very dense grass field... number of planes had nose over problems on landing last year when it was dry to the point landing points were not awarded, so this field has a history. To make things worse the club waited to mow it til the day before the contest. Their intentions were good but it was long when they mowed it and in addition to not mowing it real close, the clippings were deep on top of the surface.... so deep that when I got there I cleared a path of them to takeoff on the practice circle.  And add to that it rained a lot between the mowing and the flying and all day long the first day of the contest and in the morning the second day.  The first day classic and profile I think got rescheduled to Sunday due to the rain. In short, the weather was just not being on anyones side nor was the field.

On Saturday I flew both my electric T-Rex and electric Oriental both with no issues and no nose overs. No problems on launch either plane. I launched for Rick Sawicki on his practice flights with his electric Aldrich AG and electric P-40 on Saturday. Again, no launch problems.

Sunday was another deal. Wind got added. And lots of it. It started in the mid teens and climbed quickly. I decided to try practice flights with the electric Oriental and electric T-Rex with 4.5 inch props. I should preface this with the fact I have never attempted flight with either prop on either airplane. Also I should note that neither plane has standard gear. My T-Rex got new gear when the stock ones began bending laterally after a few flights. Since I was using 13 inch props at the time I think I made them an inch longer. And I do not fly with stock wheels. I use 3 inch wheels....ON EVERYTHING, including my glow Vector 40's with wheel pants! I fly on grass fields and not usually bowling alley smooth ones so I need the extra clearance glow or electric. Always have, always will with the conditions I fly with. The Oriental has only 2 3/4 inch wheels but long carbon gear legs that are non stock. If I had stock ones I'd use 3 inchers.  I did 3 practice flights with the oriental to try to find an rpm setting. I started at 10400 and got 6.22 sec laps. Went to 11400 and got 5.85 sec laps. That was all I could get from my motor. I tried programming in 12400 but got the same lap time as 11400 so had reached the limit I could get with the 11x 4.5 prop. The tach confirmed it as I only attained 10800 rpm on the tach at both the 11400 and 12400 rpm settings. I attempted a competition flight at this setting and after two attempts did get off. On the first attempt I suffered a prop strike and the esc cut out. The cut out sensitivity on the phoenix 45 was set at the "most sensitive" setting and it prevented any damage to the esc. But the windup on the plane was so severe that I aborted the flight after the first outside square. The plane would not have made the second one. The motor was maxed out and there was no governing available so it just wound up.  Interesting, but that is what happened.

I attempted a test flight eariler in the morning with the electric T-Rex and a 12X4.5 EP prop. I had trimmed the 13X4.5 EP apc prop to 12 inches. I normally fly the plane with an apc 12X6EP prop on 4s at 9213 rpm. To get the rpm room for the 4.5 prop I switched to 6 S and launched at 10400 rpm.  Rick Sawicki launched and said the plane just did not leave normally. It usually jumps out of his hand and leaps in the air. With the low pitch prop it left slowly and rolled about 1/8 lap on the long grass before it struck the prop and nosed over even with full up elevator input. The ice 50 smoked itself. The cutoff sensitivity was set at the next to most sensative setting on the cutout setting, not the most sensitive setting. I feel the cutout should have still prevented damage to the controller. Why it did not I will leave for the folks at Castle to figure out when they get it to repair. I have already been in contact with them about the specifics of the settings but we have not reached any conclusions at this point.  At this point it seemed pretty obvious to me that the low 4.5 inch pitch prop was not something that was going to be useful to me at this contest. I was not going to fly the plane at this point but then realized I had a backup phoenix 45 esc in my flightbox so I changed to it, repropped with the apc 12X6EP at 9213 rpm and did another practice flight. This flight encountered no takeoff issue and responded normally to launch according to Rick. Also of note, there was zero windup during the pattern I flew.

After the flight with the oriental, however, I was confused as to why it had wound up so severely. I actually thought I had changed back to the 10X5E prop I normally fly the plane with, but as I found out today when I flew the plane for the first time since the contest, I had not. So I now know what I described earlier had happened. I had flown it with the 4.5 inch pitch prop (probably the reason for the nose over as it did not have the normal acceleration on takeoff). I had gotten distracted with the T-Rex prop strike and esc failure and had just lost track of the prop change on the oriental.

I think from the experience I have come to the following learning. First, I don't think its lower pitch props that provide the lack of windup we normally see. I think its the governor and the governor has to be able to function within a workable range to both increase and decrease rpm.If you are near max rpm, or there, the governor is not going to keep the plane from winding up. This from the oriental's windup. Second, the settings we program into the timers are not gospel. When checked against an accurate tach, when we get near the top end of the operating range, they will give us false sense of what our rpm's really are. Rick and I have always tached our settings even with the digital fm-9 controller. But we also both fly in governor high mode and not fixed rpm mode, so that is what we have been accustomed to even prior to the fm-9 programming box. Third, how quick any plane can get off can be an important part of a contest if you encounter unusual grass conditions. We essentially never fly on pavement so its just another part of site evaluation to be aware of. Takeoff points are useless if you nose over. And its not power that gets you off. Bob McDonald's piped PA certainly does not lack for power, nor does my T-Rex on 4 or 6 cells. But acceleration can be an issue in really bad conditions. Finally, fourth, and I always knew this but knowing it and being able to do it can be two different things in the heat of competition, don't try to fly something at a contest you have not practiced with and worked out in detail in practice sessions even if the top expert in the world tells you you should do it. Have confidence in what you know and in what brought you there. I was enamored by what the advantage of the 4.5 inch pitch prop might be. But I had no test flight experience with it and no real knowledge of its abilities or limitations. Please do not take this as a bashing of the 4.5 inch props. I just had not tested them and am not aware of their capabilities and how best to employ them yet. One more thing, I learned to go into the cutout settings part of the castle program and set all my esc's to the "most sensitive" setting to help protect the esc from ground strike or crash damage. I think the delay setting should be very short as well but I'm still trying to get understanding on that from Castle Creations so I can't speak intelligently on that.

I should note that Rick Sawicki flew his electric Legacy on Sunday. He had no takeoff problems and flew the only PAMPA advanced or expert plane that did not wind up on Sunday in the wind. It was his normal axi 2826/12, 4s rhino 3700 mah, phoenix 45, apc 12X6EP system. Many of the glow fliers commented on it. And as Rick has gained through decades of contest experience he flew a very conservative pattern in the high winds and took a second place in Advanced. The glow plane that won (a piped PA powered SV) wound up severely and nearly crashed in the wind. I have done that in wind in contests, tried so hard to still fly the same pattern as I do in calmer conditions and killed the airplane trying to rather than learning that a conservative approach may win or may not, but you do not have to rebuild as a consequence. Maybe if I live long enough to compete as many decades as Rick has (not likely) I'll be able to learn it and apply it. Also Rick's AG did have one prop strike on takeoff when a substantial wind shift hit at launch. The esc cut out and we repositioned the plane and it launched normally. Also his P-40 profile had no takeoff issues in its class. I think that was Saturday in the rain. Interesting the plastic baggies he had around the esc and timer.

There is a learning curve as we all know. We need to share as much as we can as we learn it. I can sympathize with Jeff. I was not a happy camper after frying my ice. After the windup issue with the oriental I just decided my mind was not where it should be to fly any more that day, much less compete with any chance of doing well. I learned in 100% scale flying, if your head is not right, don't fly. So I will do that and made that choice. That one I have learned. So mine not being there I packed up and drove home. For me that was a 2 1/2 hour drive. I guess I missed a great fly off in expert, but again, my head was not there.

Still, looking forward to Signal Seekers next year. Maybe I'll work with 7 or 8 inch props to really see if that helps to deal with that field! Oh, a few did try the takeoff from the door method with their classic glow planes... didn't work either. 

As to taking off at less that full power... never on grass. Some tout it on pavement.... well, I'll still opt for full power. Rick did notice something though in his prop strike with the AG that we need to pay attention to. With the Pusher oriented props, if they strike, the plane will be deviated to the center of the circle. Another reason not to launch before full thrust.

bob branch

   The point is grass is not friendly to electric aircraft if you have to improvise runways to simulate pavement,put on bigger tires,longer LG legs,and even reconfigure the LG to a taildragger.

Why doesn't some one make a dedicated C/L speed controller with provisions for instant cutoff with motor stoppage?

SAFETY FIRST!!!!If these burn that easily,IT'S NOT SAFE.Jeff

Interesting that people with seemingly little experience don't blame their own lack of preparedness or knowledge of basic building/flying skills.    There is nothing about grass that is any more or less "friendly" to any power source. Move the landing gear forward, use larger wheels, make sure while launching that the wheels are not sitting in ruts.

Someone does make a dedicated C/L ESC that will cut the power off in milliseconds of a prop strike. The Schulze 18.46K F2B ESC is by far the best control line ESC on the market. You can even get one on sale (reg. about $230.00) on sale for $79.00 from a place in Canada. ICARE RC I think. OF course it is German made and not of the same standard as a "Made in America" ICE LITE 50  

Thanks for pointing out just how DANGEROUS these new batteries really are. Bursting into flames and all. Aunt Em never told me about this before my sister was lost in the tornado. (we moved shortly thereafter) I guess I'd better throw the 30 odd LiPo's I have in the garbage before my wife finds a smoking black spot on the shop floor that used to be me.  


Terry

Someone does make a dedicated C/L ESC that will cut the power off in milliseconds of a prop strike. The Schulze 18.46K F2B ESC is by far the best control line ESC on the market. You can even get one on sale (reg. about $230.00) on sale for $79.00 from a place in Canada. ICARE RC I think. OF course it is German made and not of the same standard as a "Made in America" ICE LITE 50

Real men don't use speed controllers that come in pink boxes.

Jeff, this is almost exactly the setup I am using on a Pathfinder, except I am using an APC 11-5. I am running out of power in the overhead eights and using 85 percent of the pack capacity on a 5 and 1/2 minute flight (using the same battery and motor as you are). What line length are you using? With the 12-6P are you able to get a steady power run all through the pattern? If so, what RPM are you releasing at? Thanks, Jim J.

Clarifications,

Jeff was NOT flying an electric powered plane at the Signal Seekers contest.

"But I guess it's not hard to place when there are more places than contestants!!".. was not referring to other people ....but was referring to his placing, where he was the only one entered in the PAMPA beginners catagory..
 


Rick Sawicki

Hi Rick,
Thanx for getting things streightened out.I certainly meant no disrespect to you,Bob,or the rest of the electric community.Since the Detroit contest was the first time I had gotten to see an E-ship fly I had little to compare it to.The next time was at FCM and that was off the L-pad..I guess the frustration of watching $100.00 burn in front of me got me a little flustered.It's not like the old days when I would gladly blow $100.00(When I could afford it) and beat myself up in the Pitts for a half hour!!!That was a $100.00 flight well spent.The Pathfinder has been repaired and converted to a long leg taildragger.I just have to wait for Castle to get my replacement shipped.Jeff

Hi Jeff,

Apologies accepted.

Now we will once again...."Have peace in the ( getting all amped up) valley"

I'm sure you will find all the folks on this forum to great people and  will be very helpful  to you for your future needs.

best,
Rick