Blade Tracking 101

[Pinecone]

For cheap, but good, woodies, I use Tech Model Products blades. $28 for 3 sets of blades, and you can mix and match length (315, 325, 335) and color.

For cheap carbon, HeliDirect has some unbranded blades that everyone thinks are Hyperions. You can also get some really cheap CF blades from Deal Extreme at times. I think about $11 - $12 a set.

[mtnbike101]

Excellent, thanks for the info!

BTW, it seems HeliDirect will have (4\1\09) some Pro 3D CF Blades for $14.22...not sure how good those are though. I just ordered my Furion 450, so I have some time!

Jeff

[phlyer]

Being new to the hobby here's a few things I found with blades. Buy several sets of woodies, weigh each blade and match them up in pairs before balancing. With a HBK2 I have had blades weigh anywhere from 17.5g to 20.5g, but with 5 sets have always been able to get pairs within .25g of each other. When setting tracking before I could hover, I would strap the helis skids to a picnic table at the park where I fly with 4 velcro straps, or at home I would set 2, 2'x4' plywood sheets I had across the training gear balls to hold it down. I could the spin it up past hover speed to set tracking.

[Pinecone]

NOT a good idea to strap a heli down. Google Ground Resonance.

If you fly a 450, get woodies from Tech Model Products. The WORST set I got, had the CG almost 0.5mm off, and perfect balance. Most are SPOT on for CG and balance.

[phlyer]

I googled I got this "The imbalance is possible because multi-bladed helicopters include lag-lead hinges at the rotor hub to reduce stresses in flight. Under normal conditions, all blades are spaced at equal angles. Shocks to the rotor mast and hub can cause an imbalance if they are sufficiently violent. Note that two-bladed helicopters are not susceptible to ground resonance because they do not require lag-lead hinges. Two-bladed rotors remain balanced through all flight conditions."
Most of us do fly 2 bladed helis without lag-lead hinges

[Pinecone]

Actually we DO have lead/lag, not hinges, but the blade bolt allows lead lag. The occasional vibration during spool up, that goes away when you get full speed, is due to the blades not being straight out, ie leading or lagging.

Do a search, at least of few people have destroyed RC helis with strapping them down aand running.

[phlyer]

Point taken. Why then are so many using turntables of some sort to set tail rotors? Is it possible the free rotation reduces the risk or is this to a problem?

[Pinecone]

IMO they shouldn't be doing this.

And anyway, most gyros do NOT need to be set up for rate mode hover.

[heli hawk]

i found by holding the heli down and done the tracking it was always different to when i had in in a hover

[Shogun]

I just pick one blade and mess with the linkage until it is right.

[dsl11us]

hello

[oscarfeiby]

hi storm.. how do you know which blade is high which blade is the low one?
Thanks

[HD ROCKER]

I'm a newbee with a B400 that crash and had to replace the frame. In my excitement to rebuild it, I dismantle the head, rotor etc.with the linkages and now " right " getting it back together correctly. Where besides the manuel can I go for help?

[JimWorm]

Originally Posted by HD ROCKER

I'm a newbee with a B400 that crash and had to replace the frame. In my excitement to rebuild it, I dismantle the head, rotor etc.with the linkages and now " right " getting it back together correctly. Where besides the manuel can I go for help?

Some resources for Blade 400 Rebuild. The videos are not great, but pay attention to the commentary. Rebuild Washout: [ame]http://www.vimeo.com/1775734[/ame] Installing Main Shaft: [ame]http://www.vimeo.com/1737223[/ame]. The Blade 400 Bible is another good resource. The web site is not "pretty", but has a wealth of information, but very hard to dig through: http://www.slyster.com/heli/b400bible.html.

[chris6414]

Originally Posted by Pinecone

NOT a good idea to strap a heli down. Google Ground Resonance.

If you fly a 450, get woodies from Tech Model Products. The WORST set I got, had the CG almost 0.5mm off, and perfect balance. Most are SPOT on for CG and balance.

Ground resonance can be avoided by loosely attaching helicopter to a surface. Secure to prevent lift off but loose enough for any vibes to be absorbed by strap or space/notch in wood block on skids. Rigid strap is welcoming disaster. I do it with my nitro to adjust HS needle in my yard. Soft ground absorbs any vibes created. To do this, your blades need to be balanced and CG'd correctly or it still can explode. Keep all persons clear when doing this with larger helos. If you are brave and do this with a 450 with your hand(guilty), your soft hand will absorb any vibes created. Just don't hold it down tight and make sure your gyro is correct. I saw a guy take a 450 to the grape when his gyro was reversed and it spun on him while he was doing this.

[Rickyd863]

I am very new to this myself ,so have been reading alot and crashing alot. But getting premium time in rebuilding...I have a stand tha i use to check the heli. it has angle feet{4}, 2" center tube and the top is 1/2" thick 6" x 8" ..this is all aluminum. I use rubber bands to hold the heli down..Since the plate is not overly large, i figured there would be no resistance. Seems to work so far.

[CanadianHeliPilot]

ahhhh! thanks!

[morgusmax]

ok so i'm a newbie as well, but i usually paint a red line on one of my blades before looking at the tracking. then it's pretty clear in flight which blade is which. you can then remove the line, or paint one on the other side for looks... or i just leave it there.

[F6Hawk]

There is no perfect tracking solution for all situations. The end goal will be to minimize vibes in the flight regime most often flown.

Being able to identify blades while tracking is nice, but not necessary. If you don't mark one (or both blades), simply shut it down, adjust ONE blade link at the grip, and run it up again. If it's worse, shut it down, and undo what you just did, times two. Of course, NOW is when you need to know which blade is which, so why not just mark it to begin with? Another tip is to mark a blade and a grip so that if you take both blades off later, you'll know where to put them back on. (Yes, it DOES make a difference which grip a blade hangs from!!)

Tracking on the ground is nice, but best to track wherever you do most of your flying, probably at a hover. It is entirely possible to have track be spot-on on the ground, out at a hover, and even further out in FFF. Why is this, you ask?

Well, blades are dynamic creatures, no matter how stiff they are. And no two are alike, much like snowflakes, though manufacturers strive for perfection, I am sure. Take a pair of blades, spin them up while on the ground until just prior to lift off, and track them there perfectly. Now pick it up to a hover, and they may be off track again. Several things can come into play here... head speed has changed from just prior to lift off to hovering, which affects the rotational relative wind, and changes the track of each blade. One blade may be twisted more than another, or have a twist in a different location along the span of the blade.

Ok, so you decide you will mostly hover, get your track close on the ground, then hover it. Spend some time making adjustments, get it perfect at a hover. Now it's time to move into forward flight, and you discover that as you progressively move faster, the heli picks up a shudder, and perhaps a video playback can show imperfect tracking. Why? Because as airspeed increases, lift changes along the span of the blade, and three stall regions come into play. This produces a twisting moment along the chord of the blade, and it will be different for each blade. A blade that twists more will have more pitch in FF, therefore it will climb more than the other.

So where best to track your blades? Wherever you plan to spend most of your time. If you are into 3D, do it at the headspeed most often flown, and accept a minor change in tracking as speed changes. If you just hover around all day, then hovering is where you want to minimize the track split, thereby minimizing vibes and future maintenance.

My experience with R/C helis is admittedly limited, unlike some greats on this forum who have been doing it for DECADES. My experience comes from working on the big fellas in real life. YMMV. Feel free to shoot down my theories with your experience, I don't bruise easily.

[chris6414]

Amen brother. Ground, hover, 60, 90 120 and 150 knots. IMDS, CH-53E AVI.