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Boca Bearings . Modefo's RC Helicopters . XHELI.COM

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Scale Model RC Helicopters > 3-bladed Hirobo Lama blade pitch - how much is enough!!
 
 
sparky767
Heliman
Location: Arroyo Grande, CA

Bought a used 3-bladed Hirobo Lama (30 size) that's in great shape but have had a tough time trying to get enough pitch for hover. I understand these blades tend to "flatten out" at speed (thanks Peter W.!) but bench setup is like 12-14 degrees at hover!

No slop in linkage - just a bit of servo shaft wobble. Tightened up the collective slop to to have the servo arm in-line (i.e., at 180 degrees rather than the usual perpendicular config) with the linkage at hover. This is per the manual but seemed so strange it took me a while to do it. Maybe it improves the rigidity of the collective linkage.

Been trying to get a copy of the 3-bladed head supplement to the manual. Figured it might have some help in it. If anyone could scan and send me the supplement (sparky_@charter.net), I'd sure appreciate it.

Got an OS32SX engine and was wondering what an appropriate hover head speed would be - using an optical tach so don't need to guess.

ANY comments, pointers, tips, gotchas, or anything else from current/past owners of one of these would be greatly appreciated! Thanks.

Dwight
05-23-2002 Over year old.
 
 
Phil Cole
Veteran
Location: Redwood City CA

About all the instructions say is to not exceed 1600 RPM.

A friend of mine has one going. It took something like 8 degrees to get it to hover at that speed. I've got one in the box, so I'm doing to find out sooner or later.

PM me if you want a copy of the instuctions. My scanner is broken, but I can afford 0.34 to mail it to you.

With the tach, there's still some guessing. Mark one of the blades so you sync up on the same blade all the time. It's easy to be out one blade, since the error is only 30%. I tried taching a Vertol once, and came up with three different headspeeds since I couldn't tell the blades apart.
05-23-2002 Over year old.
 
 
ed vega
Key Veteran
Location: nyc, queens

have it too , used the heads on a h500 I had using the hirobo seaknight / lama blades . or you can use alittle wider blades too .. need to be leading edge front heavy for stability. you won't need more than a few degrees neg and 8+ pos for general flying. keep the half stick motor speed alittle higher at 65+%. the head works well there. the cyclic inputs will be different , you'll like it.

05-23-2002 Over year old.
 
 
sparky767
Heliman
Location: Arroyo Grande, CA

Ed

Not sure what you mean by "keep the half stick motor speed a little higher at 65+%". I hover at 3/4 stick on all helis with a linear pitch curve. The curve on this Lama is from a couple degrees negative to "way high". With the Rx and Tx "on" at hover position, if I twist the blade by hand on the bench to force less pitch, I get solid resistance at around +6 to +7 degrees indicated pitch. Without twisting the blade, indicated pitch at this point is about +13 or more. Is yours like this or do I have some kind of bizarre collective slop problem? What does your pitch servo arm to linkage angle look like at hover? (Like I said in original post, mine are pretty close to in line or 180 degrees.)

dwight
05-24-2002 Over year old.
 
 
Copter Doctor
Elite Veteran
Location: daleville/ft.rucker, al

3 bladed head

hi guys!!
i built a buddy a twinstar with a shuttle in it. later i put a 3 lade head from hirobo with hirobo's blades on it and it flies great. unfotunately i have no idea what the pitch range i am using is since i usually just eyeball evrything. (eyes are calibrated) anyway it didnt seem to take any unisual amounts of pitch compared to a 2 blade system but like i said, i just eyeballed it, took it to the back yard and tweaked til it sounded right. i also have a hirobo schweitzer which will be wearing a hirobo 3 blade head soon. i will however be trying the blades that century puts out for their 3 blade head(they look like regular 30 size blades to me but will see how they work) will keep y'all posted. anyway, the three blade head on the twinstar flies great. it isnt hard, just different. prepare to see how well your reaction time is on a windy day with that bad boy............

drive a rotary, fly a rotorcraft
05-24-2002 Over year old.
HOMEPAGE  
 
 
ed vega
Key Veteran
Location: nyc, queens

sparky, I fly linear too with two blades not multiblades. whatever your hover postion is where the heli takes off from the ground , really makes no difference to me where you put your the half stick postion .. depending on scale weight as oppose to pods you might need more pitch . I usually go with higher headspeeds which required less pitch not more with linear. on a pod setup i use -9+9 pitch ranges cleanly, better collective mgmt. throttle progressively increases beyond the end of collective pitch range. I only need 12+ at the very bottom of an auto. in a 3 bladed head it's more like -3, +10, +12 for auto. pitch arms at 10o'clock and 2o'clock max . blades made to flex ..

pitch is added with cylic too . you have to consider the amount of cyclic pitch added to your collective at anyone point. the soft dampened multiheads and skinny blades , don't auto well either, symetrical, general upright flying is about the norm. 13+ degrees is a stall condition unless you got the headspeed, and those skinny little blades won't save your heli when you need to auto. they bleed off inertia too quickly. yes theres extra play with the hirobo head, theres slop there.

emile, yes check out the century head and see if it stiffer and what types of blades they use with it.
ed
05-24-2002 Over year old.
 
 
Phil Cole
Veteran
Location: Redwood City CA

I have a new MRB conversion kit, and I noticed the blades don't appear to be weighted.

Has anyone added weights, and did it improve things like stability and autos?

I had a look at the Century head at one stage, a while ago. From memory, it's very similar to the Hirobo head (rubber-damped flapping blade axles), but a bit softer.

The softness was claim to improve the hovering qualities. This may be to the detriment of its forward flight characteristics, however. Only one way to find out.....
05-24-2002 Over year old.
 
 
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Scale Model RC Helicopters > 3-bladed Hirobo Lama blade pitch - how much is enough!!
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