Hi all,

Just had my first tailboom strike with my CP Pro today. I was trying out some new blades, which are made of heavier wood than the stock blades, and I am certain that that was a contributing factor in the strike, it happened on a semi hard landing, but no more so than I have had in the past....

My question is, a pretty knowledgeable guy at my LHS told me once that leaving the blades "loose" in the grips contributes to tailboom strikes, he showed me this heli he was working on, and the blades were pretty stiff in the grips, compared to how I have been running mine, and how I have seen suggested in other literature.

I was examining the heil after the strike, and sure enough, the blades won't easily "reach" the tailboom when they are straight out from the rotor head...but if they are swung back a little, the angle changes, and they seem to be much more likely to hit the boom?

Any comments/experience/advice on this? I really love these blades (HD 1141's from Heli Direct)....they make the CPP much more stable for hovering and slow flight...

Any other comments suggestions (besides not landing hard!) to reduce the possibility of a tailboom strike?

I never had this happen with the stock blades...

Thanks a million all!!

Glenn

They should not fall if you put them parallel to ground, but JUST not fall, any tighter and you'll have issues with control. So keep tightening until they just don't fall towards the ground.

DY

Glenn,

Did the new blades make you crash? I am not too sure on what would cause a tail boom strike. I know on the T-Rex's when they had the gyro in the normal spot of helicopters the flybar would strike the gyro in a crash. So something has to cause them to go at extreme angles. When I fold my blades back to go into my blade holders I can tilt the blades down and they will touch the boom.

Nick

Hey Nick,

On the contrary, I don't think the blades caused the crash...it really wasn't a crash as much as a fairly hard landing...I got it a little out of whack and went to set it down quickly. It really caught me off guard, I wasn't expecting anything to happen, and WHAM...the whole thing self destructed! That's the drawback of flying in a confined space, I sometimes just have to put it down if I get in a bad spot. The blades are great; the heli has never, ever flown better. They are heavier, and add tremendously to the stability of the heli. I don't imagine someone doing 3D or aerobatic stuff would like them, but for me, they are awesome! I love them...I have two more sets, I am not going to give up on them. Maybe the boom strike was a fluke, I don't know for sure, but I'm sure going to give it another try...the blades make it fly so much better, I have to try to make them work!

I also bent the spindle, but that's no biggie, saw one at the LHS the other day, they are not scarce like the B400 ones. I'm going to rebuild tomorrow, providing I can get all the parts I need. It's probably a good idea for me to look over the whole heli, I have been doing nothing but flying it, not really keeping up on it like I should be.

The CPP was flying better than it ever has...hopefully, it will fly even better when I am done. I am not completely certain that the spindle wasn't bent before this incident, I have never checked it before...so we'll see.

Thanks, as always for the concern/advice!

Glenn

Hey DY,

Thanks...that is what I have heard/read...I will continue to use that method, despite what the LHS guy said... I don't really see the connection between the boom strike and the tightness of the blades anyways.

Take care,

Glenn

Doc,
Is there a difference between the blades - symmetrical Vs flat bottom? I'm still fighting old habits learned with the Fixed Pitch. When I'm in a confined area and I need to bring the heli down, I just dump the throttle. On the fp that just kills the power. On the CP that pitches the blades down - pushing the heli down. I'm talking like you don't realize that - and I'm sure you do. Never-the-less, I'll continue.
Example; If you have the heli on the ground in idle-up and pull the stick back the blades will come dangerously close to the boom even at high rpm. If the grips are a little loose and the blades go negative (as when you chop the throttle), and that situation forces a somewhat hard landing, and throw in some extra inertia because of the added weight - well there ya go.

I asked about the blade type because symmetrical blades have more lift when flying inverted - thus they have more negative lift when you cut the throttle. Is there anything in that thought?

About the tightness of blade grips, I've heard what DY said from several others. I've also found that it is important that both grips have the same tightness or the tail will bounce. If the grips aren't the same tightness it must be really hard to get good tracking. I run mine pretty snug - probably more snug than DY said. I'll adjust mine just a bit looser.

Oh, and what the lhs tech showed you about turning the blade back in the grip and how that allows the blades to get close to the boom, you can't just turn one blade. You have to turn them both toward their trailing edge. Two blades on one shaft - equal and opposite. What one blades does, the other must do. Turning one blade is never going to happen on a spinning rotor.

Anyhow, this was just a bunch of thoughts early in the morning. Hope you get the bird fixed, and enjoy those new blades. I'm going to get a set of Align 325 Fiber blades for my Beltrex 400 CP . They are fiber reinforced plastic (FRP) with a CF spar down the center and an internal weight at the outer end for better stability. If they are not so good for 3D, they will be more good (more gooder?) for me.

Hey Solo,

Thanks much for the input and suggestions! Yes, I have converted over to exclusively flat bottom blades, I have no interest in 3D or any aerobatics at the present time, any ways. I have found them to increase the stability of the inherently unstable CP pro quite a bit, particularly these, which are nearly twice as heavy (15g vs. 8g) than the stock Eflite flat bottoms.

You bring up a very interesting point, and that is the blade pitch. I have not checked it in quite some time, the heli has been flying very well, and I didn't feel the need to. I'll double check the pitch at zero throttle and see where I am...I'll bet I have some negative in there!

I also may have had the cyclic pulled back, the thing happened so fast, and I was flying FWDT (Flying While Dead Tired), been putting in some overtime at work, and I probably did something stupid, I am sure. I will do the rebuild, and pay close attention to the pitch, so maybe I can decrease the possiblity of another incident like this one. Fortunately, I didn't hurt the tailboom, it's made of carbon fiber, and held up very well.

Point well taken on the blades turning back in the grips, I just can't picture that happening while the blades are turning at full tilt, and as you said, what one does, the other has to as well...must be some old wive's tale of the RC heli type!

Well, it's off to the LHS for some parts...hopefully I can get it back in the air soon. As hard as this CPP is to hover/fly, I still seem to love it for some reason! I have a couple of B400's and I think that wrestling with the CPP to hover and fly it actually is good practice for the bigger, more stable birds...

I am going to give these blades a serious try, as they really do make the CPP much more pleasant to fly. I have two more sets, so I'll give it at least that much!

Thanks again for the advice/ideas! I always appreciate the input and ideas of you guys!

Glenn

Glenn
Well, it's off to the LHS for some parts...hopefully I can get it back in the air soon. As hard as this CPP is to hover/fly, I still seem to love it for some reason! I have a couple of B400's and I think that wrestling with the CPP to hover and fly it actually is good practice for the bigger, more stable birds...


I can sure relate to the love/hate relationship with the smaller helicopter. I know I should be putting all of my effort into my Beltrex 400 CP , but the little Falcon fixed pitch is just so much fun to mess with that I still fly it. It is certainly a pain in the butt, but there is sooooo much to be learned from the FP. It seems to fill the void between the sim and the Belt. A real mistake flown to completion results in a real crash and either a little re-adjust time or a minor repair.

I still am of the opinion that one of the strong shortcomings of the sims is that there is no pain. And no pain, less gain. I suggested once that following every sim crash the flier should determine the approximate loss - had that been a real crash. Now put the value of the damage in your piggy bank. Of course you are just moving the money from one pocket to another, but flying the sim will make you sweat when you realize that dumping the throttle is not an option! And of course you are collecting funds toward your next real world crash.
Through two days of OP-ED comments, we sort of decided that even dropping a quarter into cup following every sim crash would build a repair fund, and make sim flight a bit more meaningful for those of us not maximizing our sim time.

Enough of that. I hope you acquired all of the parts needed and you are back in the air soon.
I finally did get my Belt out in the front driveway and did a little tail in work at 4 ft up and again at 10 feet up. The obnoxious wind decided that the helicopter should become someone's hood ornament, but I kept that from happening through the use of my incredible cunning and skill. Or some might call that luck. As they say, if you can fly a fixed pitch or a Blade CP, it makes flying a larger helicopter much easier.

Best of luck.

Hey Solo,

Very well put on the small heli, for me it is a bridge between the sim and the B400, exactly.

I also agree with you on the sim. I find myself becoming very complacent on the crashing, and not taking it like I really should, and absolutely conentrate on not crashing, even if I am trying something new...

That being said, I also believe that the sim has been the single most important part of my learning to fly the helis, as I can just plain old get more time in on it than I can 6-8 minutes at at time, IF the weather is good, and IF the heli isn't down for repairs, and IF it isn't too dark outside, etc...you get the picture.

What I have been trying to do of late is alot myself a certain amout of time just to play on the sim...do crazy stuff, inverted, attempt 3D, etc, to get it out of my system, and then I try to practice just as closely as I can to the level that I am actually at on the real thing, which is just simple hovering in all aspects, and some very simple little circuits, usually left to right, and vice versa...

I may actually implement your plan, and put a piggy bank on the computer desk, and make myself pay for the crashes!

Thanks for the insight, and comments, well taken!