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03-29-2005 01:18 AM  13 years agoPost 1
PetSketch

rrApprentice

Stormville, NY

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Title kind of sounds like a song title or the name of a band ... LOL.

Anyway, I had my first boom strike yesterday with the wooden 315's. I lost orientation at dusk and landed hard. OUCH! Trashed blades, seesaw, grip, etc. I'm sure you all know the routine.

My question is: What blades (or mods to head) do you Trexperts recommend to mitigate this? I'm thinking shorter 280mm carbon might help, but I solicit your opinions. BTW, I'm not doing any 3D, yet .... if I could afford a trip to the Netherlands, I'd join Annihila for lessons in 3D.

Thanks -
<>< Jim

"My wife is definitely a saint"

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03-29-2005 02:17 AM  13 years agoPost 2
Coolpowered

rrKey Veteran

Youngstown, ohio

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you might want to try the align 305mm blades, right now you want to keep it cheap as possible, carbons cost a lot more, and you will be having more mishaps for a while yet. and are you sure it was a hard landing or a controlled crash? just kidding. hope this helps

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03-29-2005 02:22 AM  13 years agoPost 3
PetSketch

rrApprentice

Stormville, NY

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CoolPowered
You're right! You caught me in an exageration .... it indeed was a QUASI-CONTROLLED crash!

"My wife is definitely a saint"

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03-29-2005 02:46 AM  13 years agoPost 4
thunder21

rrApprentice

College Park, MD

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Stiffer blades won't help you to always avoid boom strikes. If you slam the heli on the ground, even the carbon blades will boom strike. But stiffer blades will make the heli more responsive. And less likely to boom strike during maneuvers like tic tocs, etc.

The next best thing to usingcarbon blades is to recover the stock wooden blades with heavier shrink wrap. I use 37mm wide .02mm thick shrink wrap to cover my blades. They are much stiffer than the original blades. The covering adds 4-5 grams to each blade but it's worth it.

http://www.battlepack.com/misc.asp

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03-29-2005 03:59 AM  13 years agoPost 5
ScotY

rrApprentice

USA

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As Thunder21 says, just about any blade will boom strike, given the right circumstances. In flight, rpm is your friend....lose too much and you risk a boom strike.

Someone suggested the heatshrink covering fix to me a while back. Out of curiosity, I tried it. Additional stiffness with a little adverse weight distribution...sounded like a reasonable trade off. I didn't think it would hurt any but flying it showed otherwise. I couldn't get the blades to stay in track (they worked well prior). I'd be cautious with that modification. It's not the additional weight, it's where you put it that is the problem.

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03-29-2005 06:29 AM  13 years agoPost 6
thunder21

rrApprentice

College Park, MD

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ScotY, I'm confused about the last statement you made. Did putting the heavier shrink wrap on your blades change the CG somehow?

One thing I noticed was that you have to be careful to not warp the blades when applying the heavier heat shrink. The original heat shrink was only half the thickness so it affected the straightness of the blades very little. If a twist/warp happens with the heavier shrink wrap you can straighten it out by twisting/bending the blade in the opposite direction while gently applying heat. The shrink wrap will keep the new blade shape when it cools.

Another cause of poor tracking can be the fairly loose blade dampeners (o-rings) included with the stock kit. Many people have said the carbon fiber blades due to their stiffness and weight have poor tracking with the stock dampeners. Using stiffer blade dampeners usually solves the problem.

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03-29-2005 06:42 AM  13 years agoPost 7
ScotY

rrApprentice

USA

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Hi T,

Yes, that is correct, or at least that is what I assumed. Think about it...if you put 5 grams total onto the blade as covering and you have a greater area behind the center of pressure (or blade bolt pivot point might be more relevant), this will move the chordwise CG towards the trailing edge of the blade.

I was worried about the heatshrink warping the blades also. I chose the thinnest heatshrink I could find and carefully and evenly heated it. Got lucky...they were and still are perfectly straight. So, that was not the problem for me.

I don't think it's always safe to say soft dampening is what causes problems with blade tracking. There are some rotor heads with zero dampening at all. The K&S swing head is one that comes to mind...it has no rubber dampeners of any sort and those heads run very, very smooth. Anyway, back on topic...I really think the problem is more than 50% blade design. I'm willing to be that in the future, we will see wide chord micro helicopter blades and they will be built right, balanced, and fly perfectly...soft dampeners or hard.

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03-30-2005 05:32 AM  13 years agoPost 8
ScottH

rrApprentice

Long Beach, Ca.

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First, if you know you are going to hit the ground, hit the hold switch. Saves a world of hurt.
Second, most crash boom strikes are not from the blade flexing, but swinging back in the grip, which allows them to swing really low and smack the boom. Tighten up your blade bolts. You should be able to move the blades with a bit of force, but they should NOT be able to freely swing around in the grip.
Scott

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