Hello All,

First let me start by saying that I may know the answer to this one but I'd like to get your opinions and other thoughts. Sorry for the length.

A couple weeks ago I had my first crash while learning to hover (I'm still on training gear). I only had to replace the see-saw arms, head links, and the main blades. I installed the new parts, balanced the blades and setup the pitch. In order to get a head start on tracking, I measured the pitch on both blades and adjusted the links so that both were as close as possible so when I fired it up at the field, I would not have to adjust too much. Well, at the field I could not seem to get the tracking correct, the "marked" blade (I colored the tip with a marking pen) was always higher than the other. I tried 3 times to adjust the link but it made no difference. Then someone explained that my rotor speed was too low and tracking cannot be done w/o proper speed first. He made some adjustments to the carb and measured my speed at 1650. AOK. He also made one linkage adjustment and blades appeared to track almost perfectly. Everything OK right ? Well, out of curiosity I just sat down and re-measured the pitch of both blades. Turns out the "unmarked" blade was zero (low stick) as I wanted it, while the "marked" blade was -5 !!! WOW I then proceeded to measure the pitch at the root and tip of both blades (I usually only measure pitch at the root). The "unmarked" blade is 0 at the root and -2 at the tip while the "marked" blade is -5 at the root and +2 at the tip !!! Son of a b*^#@ !!! My eyeball could not see the warp in the "unmarked" blade but the "marked" blade that had 7 degrees difference was definitely noticeable.
Here is my summary: The average pitch of the "unmarked" blade is -1 and the average of the "marked" blade is -1.5, close enough (measuring pitch is not quite an exact science) so the blades appeared to track descently while in the air.
Here is my solution: Send them back and get some glass or carbons.
The blades are 550 Revolution CP woodies from Heliproz.
Any comments ?

Thanks.

I have faced the same dilemma. I now only use the pitch gauge for very general settings, because it seems that is all they are good for. Another words, I set the blades to what the book says at home, pos, neg, pitches, idle ups, etc. Then at the field I first adjust the tracking by just picking a blade and adjusting it, if the blade is further off I adjust the same blade back the other way plus a turn or so. I just put a little dot with a marker on one blade so I know which one I'm adjusting. After getting the tracking in line I bring it up to a good hover for a min. or so then check the tracking again. That's it for the tracking.
Now for the pitch curves. I start by doing a few full throttle full collective pull outs and just listen to the engine and note how it's climbing. I then use my end point adjustments and pitch/throttle curves to get it where the heli climbs smoothly and the engine rpm remains constant, I can tell more with my ears than I can with a pitch gauge. I do the same with my idle ups.
The bottom line here, if the heli flies well, you have no vibration problems, you don't have to re-adjust your settings every other flight, and it reacts consistently to stick inputs.

In my opinion, it's fine, fly the heck out of it.

Oh, and after doing this I'll bring my tach out and check the head speed, and it's always between 1600 - 1700 at a five foot hover. Which according to my info that's about where I want it.

Good Luck

if one blade is warped, it no longer has a symmetrical airfoil and you'll get vibration. i doubt it will stay in track at your full pitch range even if it's tracking at hover pitch. go for the glass or carbon blades and save yourself a headache.

A replacement set is on the way. I'll check them out when they arrive. If they're warped also, I'll just get my money back and order some glass or carbons. This seems the easiest and cheapest way to go while I'm learning.
Anyway, is there any problem with continuing to fly with these blades as long as the heli appears to fly OK w/ no noticeable vibration ?

Don't take me wrong, if a blade is bad it will let you know and by all means do NOT use it. It will cause much wear on things and possibly disaster at some point and time.

I'm using glass blades from Airborn Models on my Venture and they are working very well and best of all they are $28 a set.

Here is a link to the page with the blades if your interested.

Here is the one's I purchased:
Fiberglass 550 mm symmetrical

http://www.airborne-models.com/

Go to this web site, then go to the bottom of the page and look on the left side for this:

Plane Parts and Accessories
[ Plane Parts ]
[ Accessories ]

Click on Accessories, go to the second page on the very bottom.

bigwave,

Any problem with folding your glass baldes into the holder ? The stock woodies required a notch cut near the root to enable folding into a holder and attach to boom. Even these current ones require a small indentation so they will completely fold. My guess is that glass or carbon would not allow ANY such modification.

Thanks.

FWIW it's a very unsafe practice to modify rotor blades in any way shape of form. Cutting a notch near the blade grip is asking for trouble.

They work perfectly, the root on these blades is some-what extended compared to some of the others. They fold, and fly very well.

I'll try to take a picture here in a little while and post it. Check back in a few hours.

Fury,

Yea, I agree. I had cut the notches while assembling, this, my first ever R/C machine and had I known then what I have read now, I would never do that again. The field "expert" looked at it b4 starting the engine for the first time and said it s/b OK. In any case, they were splinters after my 4th tank so it's moot now.

There is no modification to these blades.

That's bad news ifyou're cutting notches into the root of the blade... Modifiying your blades is a big NO NO!!!! They may seem allright but They're not!!! Tiy're gonna get bit if you do that.


One thing you should cehck after a crash is your Spindle..... They always bend a little..and the main shaft. Take them out and roll them on a flat surface to make sure they're still true.


If you're still just learning to hover then don't wast your money an an expensive set of blades as you'll probably crash again before you will even be able to get any benifit from the CF's (with the exception of balancing)

Just my nickels worth.

bigwave,

Aaaah ! Great pix ! Obviously not a problem. I will definitely order a pair if the replacements are also warped. Thanks.

HSH,

Checked the spindle and sure enough, it is slightly bent. Actually took several rolls on different surfaces to tell but it looks bent by the slightest of margins. Must this be replaced b4 flying again ? Doesn't seem like that slight of a tweak would effect things much but I don't know. What'ya think ? Also, I don't really want to take out the whole main shaft. When I fly, the head button appears like it's not even moving from turning by hand to hovering and every speed in between. Is this enough to verify that main shaft is OK ? Is there any other way to sufficiently check it w/o full removal ?

Thanks.

Sounds like your main shaft is ok if you don't see a wobble in it. As for the spindle.... a little baend will deffinatly make a big differance. You can try and bend it back straight if you want but it's easier to just get a new one. As for flying with it bent you most certainly can..... It's just pretty hard on the machine... and will cause more slop to develope..... So if you want to save the machine from un-necessary wear and tear get that spindle straightened out or get a new one.... THey're pretty inexpensive.

HSH,

Thanks for the honest reply. I'll include in my next order. I need to get a header tank anyway. I may fly this weekend but I may instead go to the show in L.A. (time is at a premium). I guess CY will be there so it may be quite an "eye opener".

Thanks