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  1. #1
    Moderator daveopam's Avatar
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    50CC Extra 300 snap

    I am hoping someone has one of these and can help me work this out. I have a 50CC Extra 300 that will snap with elevator input. It is worse with power off but can still happen under part throttle. It is not a violent snap but the plane will rotate about 40 degrees to the right. I have had it snap more than that once but it was tight turn on knife edge 1/4 throttle and I am sure the rudder input was the cause of the extra rotation. My CG is dead on the AW recommendation. I was thinking about moving it back some to see if that would help. I had a Funtana long ago that needed the CG way back to not snap with strong elev input.

    BTW I have had the incidence meter all over the plane. Both wing halves and stab halves are level to each other. I don't think it's a servo issue as a hard pull under power is not an issue.

    Thanks, David
    I never want to see a crash. But I don't want to miss one either.

  2. #2
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    RE: 50CC Extra 300 snap

    I can't answer your question but I just lost a 30cc AW Edge 540 that way. I had the plane setup according to the instructions. I know if I gave it too much elevator in a loop it would drop the right wing at the top of the loop. I did have the side force generators that AW sells installed.I thought I might be acharacteristicof the Edge 540 and that the plane was ok. I was thinking about replacing it with an AW Extra 300 since I am not a fan of the Edge 540 anymore. I don't think you should have to worry about a wing dropping or what some say is a tip stall.
    Anyway, any help or suggestions for us would be great. Thanks.

  3. #3

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    RE: 50CC Extra 300 snap

    Daveopam,
    For some reason, ALL of the Aeroworks Extra's I've seen or have personally have done the exact same thing. They will drop the right wing with elevator input. I have seen the 50cc size do it, a good friend of mine and I both have the 60-90 size that do it and I've read others say that the 30cc does it. There is a simple solution to the problem that my friend told me that fixed his problem. What's happening is the right wing is stalling before the left wing with elevator input. If you have your ailerons on separate channels, go into your subtrim for the right aileron servo and lower the aileron by a click or two, then test fly the plane again. Repeat procedure as necessary until the wing quits dropping on elevator input. If you have your ailerons on a Y harness, just turn your aileron linkage out a turn or two at the control horn end to accomplish the same thing. My 60-90 size Extra took 5 clicks of subtrim on my Futaba 12Z to fix mine.

    Nikonlarry,
    I'm sorry you lost your Edge, but I believe the problem and the solution is the same as the Extra.

    Take care,
    David
    Fly Safe and Have Fun ! ! !
    Ultra Sport Brotherhood #22

  4. #4
    nikonlarry's Avatar
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    RE: 50CC Extra 300 snap

    David, Thanks very much. Sounds like good advice for any plane the exhibits that behavior. I guess you trim out the plane and then adjust the subtrim on the right wing. 

     I did find this ebook on trimming from Peter Goldsmith.

    http://ebookbrowse.com/peter-goldsmith-trimming-chart-pdf-d30285711

  5. #5

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    RE: 50CC Extra 300 snap

    Nikonlarry,

    You are absolutely correct, I failed to mention that in my initial response. I assumed that since Dave's post was regarding a 50cc plane, that the plane was previously balanced. Thanks for the link to the trimming chart, I'm going to review it and see what it's all about.

    Take care,
    David
    Fly Safe and Have Fun ! ! !
    Ultra Sport Brotherhood #22

  6. #6
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Thanks guys for the input. When the Oklahoma wind lays down I will try dropping the right aile a little. My ailes and elev halves are all on separate channels so I should be able to get it done. I hate to move the CG because the plane is almost hands off when inverted.

    I will post and give a report of what was done and the results after the fact.


    Thanks again, David
    I never want to see a crash. But I don't want to miss one either.

  7. #7

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    RE: 50CC Extra 300 snap

    Hey David,

    I failed to mention one other thing that is probably relevant and it more than likely it applies to you as well. I have a transmitter that allows me to adjust the amount of servo movement with each click of trim and I have previously set the value to the lowest amount of movement. Also, it took me 4 clicks of subtrim to fix the problem on my 60-90 size Extra and the droop in the right aileron is almost imperceptible.

    I hope the solution solves your problem with your plane like it solved mine, because I've looked quite hard at getting the Aeroworks Extra 300 as my first 50cc aerobatic bird.

    Take care,
    David
    Fly Safe and Have Fun ! ! !
    Ultra Sport Brotherhood #22

  8. #8
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Thanks David. And please don't anybody think I don't really enjoy this airframe. I would recommend it to anybody. It's just not an all out 3D animal. Anything you want to throw at it from they IMAC book it will handle. Mine is DA-60 powered and vertical draws ooohs and aaahs when I fly it. Slow rolls, 4 point rolls and rolling circles are some of the best I have done with any airframe. If I could just get this one little tick solved.

    Will report back after she flys again, David
    I never want to see a crash. But I don't want to miss one either.

  9. #9
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    RE: 50CC Extra 300 snap

    Dave, I'm thinking it's a combination of weight and elevator throw. Maybe CG related also. Leaves me with 3 questions. What is all up weight? How much elevator throw when it snaps? What flight tests have you done to verify CG?
    Of course it's true, I read it on the Internet.

  10. #10
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Speed, the AUW is 17.25lbs with out fuel. I have a ton of elev throw but also have a lot of expo. I know it's about 1/4 stick movement but I can't tell you how many degree or inches that is. The only flight test I have done to check CG is hands off inverted. @ hands off inverted it has a slight drop. By slight I mean 10' over 500'. At least that's my best guess. Sometimes I think KE edge flight is a pretty good CG indicater also. While it has a slight right roll during KE the pitch is nearly dead on.

    I also want to reiterate, most of the problems or off power. With a little throttle in it I have only had the one KE episode I talked about in post one.

    Thanks again, David
    I never want to see a crash. But I don't want to miss one either.

  11. #11
    speedracerntrixie's Avatar
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    RE: 50CC Extra 300 snap

    David, the weight seems pretty reasonable depending on wing area. I have seen other 50cc airplanes at over 18 lbs perform well. Your CG tests are throwing me a little. The inverted test sounds about right but most aerobatic airplanes I have set up have a slight tuck to the gear while in knife edge unless the CG is on the forward side. A forward CG will contribute to an elevator snap. Running a lot of throw will cause the snap as well especially with alot of expo. Anything 50% or more on expo will give you that soft feel up to a certain point all of the sudden you have a ton of throw. What I would do at this point if it were my airplane is to back the expo to 35% and max throw to 20 degrees. This should cover all flight envelope except for 3D. If the elevator feels too soft at that point then you may look into CG. A couple more questions while we are here, have you measured the airplane to see where the wing, stabs and thrust angles are at? Do you have some up elevator trimmed in? Does the elevator trim change from half to full throttle?
    Of course it's true, I read it on the Internet.

  12. #12
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Speed, when the plane was new I had some issues with the stabs not being true to each other. AW sent out a new pair and the problem was solved. I tell you this because I blocked the plane up at that point and using 2 incindence meters went over both stabs and three different points on the wings. I wanted it straight and I think it is. As for as the incidence difference from the wing to the stabs I know there was about 2 degrees difference but I cant remember which way it was. My main goal at the time was to get it straight right to left. As for the thust, I never checked it. After bolting up the DA the spinner hit the center of the cowl so I left it. On this airframe the engine could be shimmed to match the cowl, but the way the cowl is built there is no adjustment there. I do not have any up elev trimmed in and the plane does not change trim with airspeed.

    On my next trip to the field I am going to try less throw and and cut back on the expo. I will take note of my stick movement when it snaps and after landing see how much throw that really is. I also want to try dropping the right aile a click or two. I am just worried this is going to cause other issues. I am going to have to trim the elev halves to compensate for the dropped aile and I am afraid this is going to effect the tracking. As for the CG. I looked at it the other night and I can move the ignition battery back about 12" with out much trouble. As it is the battery is about 3" behind the CG. An extra 12" is not a huge amount of weight on this size of a plane, but I may try it after trying the other things above. The pack is a 5 cell nicad that uses sub "c" cells so it is fairly heavy.

    Now all I need is a good Oklahoma day to tinker. These are few and far between in the last 3 weeks.

    Thanks again, David
    I never want to see a crash. But I don't want to miss one either.

  13. #13
    speedracerntrixie's Avatar
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    RE: 50CC Extra 300 snap

    David, 2 degrees difference is pretty large. I don't think that it's a cause of your snaps but it will create issues. Not knowing if it is positive or negitive I really can't say what the ill effects are going to be. On my aerobatic models I set the stabs and engine to zero and the wing at +.5. Reason for this is that the wing needs positive incidence to support the weight of the airplane. You can set everything to zero but then you would need to fly the whole airplane at a positive angle. IMO this makes it harder to get knife edge and verticals on the money. You may want to correct that 2 degrees before anything else. I do however feel that the snap issue is just over application of elevator. Your wing incidence could be masking a nose heavy condition as well.
    Of course it's true, I read it on the Internet.

  14. #14
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Thanks Speed. If the wind cooperates on Sunday, I hope to get some of this sorted out.

    Thanks again, David
    I never want to see a crash. But I don't want to miss one either.

  15. #15
    Moderator daveopam's Avatar
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    RE: 50CC Extra 300 snap

    Well I got to put three flight on it Tuesday. I did not try everything I wanted to from the advice above, but here is what I did try. Moving the ignition battery is about a 30 minute job. So I did that in the shop on Sunday. Changing the CG did not help the problem at all. I am actually going to need to reverse this before I fly it again. This change made the plane climb when hands off inverted and made it difficult to land. It was trying to balloon up as it got close to the ground and I had to use a little down elev to stick the landing. I did adjust the elev throw and expo. I took 15% out of the throw and added 5% of expo. I had to switch to high rate to hover it but this took about 75% of the snap out of the plane. It also made the snap slower and I was able to catch it before it rotated as far.Taking the elev throw down even further should help even more.

    Earlier Speed ask me about KE flight and I said it was straight but with a little roll. I paid a little closer attention on Tuesday. It does tuck to the gear a tiny bit. Evidently I was instinctively flying the correction in and it was slight so I never really noticed. I will try this test again after I move the CG back where it was to see how much difference it makes if any.

    What I did not get time to try was dropping the right aile slightly to see if this changed it. To be honest this will be a last resort thing to try. ( no offense to the suggester) The plane does everything else so well I am in no hurry to upset the rest of the flight envelope to fix this problem. I have been flying it out of and around this condition for a year. One Sunday when I have time I may go ahead and try it just to see what it does. Before that though I am going to reset the CG and take another 10% out of the elev throw.

    Will post back after I try some more. Thanks again, David
    I never want to see a crash. But I don't want to miss one either.

  16. #16
    Moderator daveopam's Avatar
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    I know it's been a while. But the last 3 flights have not seen any sort of snap. I have made several changes in the CG, the throws, and the expo on this plane. I have found a happy median on the CG. It is a little floaty after 1/2 of the gas is burned off but I don't have to push the nose over to land it. Hands off inverted the plane has almost no drop in ALT. Is the problem 100% fixed? No. If you are putting along just above idle and pull hard elev on high rate, it is going to drop the right wing. Airspeed will cure this as will prop wash.I am hesitant to call it a flaw as this is not the only plane I have flown that does this. I will say that this plane is more suited to IMAC than 3D. It does some 3D well, but that is not it's strong suit. For IMAC type flying the plane excells. The lines are very straight and clean as are the rolls.
    In conclusion, this is a very nice airframe. I am very happy with how it flys even though it took more tinkering to get it right than other planes in my fleet. If you want to strictly 3D look to the AW Extra 260. If your taste lay somewhere in the middle, this is a nice airframe.

    David
    I never want to see a crash. But I don't want to miss one either.

  17. #17
    MTK's Avatar
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    Quote Originally Posted by nikonlarry View Post
    I can't answer your question but I just lost a 30cc AW Edge 540 that way. I had the plane setup according to the instructions. I know if I gave it too much elevator in a loop it would drop the right wing at the top of the loop. I did have the side force generators that AW sells installed.I thought I might be acharacteristicof the Edge 540 and that the plane was ok. I was thinking about replacing it with an AW Extra 300 since I am not a fan of the Edge 540 anymore. I don't think you should have to worry about a wing dropping or what some say is a tip stall.
    Anyway, any help or suggestions for us would be great. Thanks.
    Wing loading is too high...any way you can remove some weight from the crate? It also sound to me that you are quite a bit tail heavy. Can you bring the cg foreward?
    Regards,
    MattK
    (Rcmaster199@aol.com)

  18. #18
    Moderator daveopam's Avatar
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    No way to make it lighter without buying CF wing tubes and gear. I am at 17.5 lbs which is within specs. I know I am behind the recommended CG range, but this is where I like the overall flight envelope the best. I do thank you for the suggestions. For now I am just going to enjoy flying it and leave the serious 3D to something else in the hanger.

    Thanks again, david
    I never want to see a crash. But I don't want to miss one either.


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