RunRyder RC
 6  Topic Subscribe
WATCH  1 page 645 views POST REPLY
Scorpion Power Hitec RCD
Slowpoke

Key Veteran

Dublin, OH

My Posts: All  Forum  Topic

I am building a custom/scale project.

How do I determine if there is adequate clearance between the main and tail blades?

01-16-2017 07:25 PM
PM  EMAIL  GALLERY  Attn:RR
ticedoff8

Key Veteran

Morgan Hill, CA. USA

My Posts: All  Forum  Topic

Use a tape measure?
Honestly.

Turn the main and tail rotor blades until they are at their closest point.

You could get fancy and use a piece of string that is the same length as the main blade and see if the main and tail blade's arcs intersect

Believe 1/2 of what you see and none of what you hear.
Fake News will be the downfall of our Republic!

01-16-2017 07:41 PM
PM  EMAIL  GALLERY  Attn:RR
Slowpoke

Key Veteran

Dublin, OH

My Posts: All  Forum  Topic

ok, sounds straight forward, but I thought there was more to it than that.

So....

If I'm looking at my heli from above, and see an imaginary line outlining the circumference of the main blade tips, as long as tips of the tail blades don't touch that line, I'm ok?

I'm experimenting with different swash types, and I'm thinking I read that going to a DFC style head (which usually has a shorter mainshaft, putting the mains closer to the boom in a downward direction), made the tail blade selection more critical. Or were they possibly referring to boom strikes?

These 900mm blades are $$$....

01-16-2017 08:18 PM
PM  EMAIL  GALLERY  Attn:RR
CostaRicaHeli

Senior Heliman

Costa Rica, Central America

My Posts: All  Forum  Topic

From the side

Look at the heli from the side with the main blades parallel to the boom and tail blades at the closest point to the mains in their arc.

Franz

01-16-2017 08:48 PM
PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR
ICUR1-2

Elite Veteran

Ottawa, Ontario

My Posts: All  Forum  Topic

Boom strike depends on dampeners and height of head and how loose the blade grips are . So a low head with soft dampeners and loose blades is a guarantee of a boom strike

spending time, paying attention

01-17-2017 01:52 AM
PM  EMAIL  GALLERY  Attn:RR
Dr.Ben

rrMaster

Richmond, VA, USA

My Posts: All  Forum  Topic

The rigidity of the DFC heads allowed for shorter mainshaft length without a boom strike. Of now experience has proven you can nix the DFC and still use a short mainshaft, have no boomstrike concerns, and avoid the pitfalls of DFC. You can get away with some overlap of tail blades and mainblades IF you have adequate mainshaft height and don't make a habit of hard landings mixed with aft cyclic.

Ben Minor

Team Synergy Team Futaba Team Kontronik USA
Progressive RC

01-17-2017 03:02 AM
PM  EMAIL  GALLERY  Attn:RR
oldfart

rrProfessor

Vancouver, Canada

My Posts: All  Forum  Topic

Also of consequence relative to blade/boom strikes is the tightness of the blades in the blade grips. The tighter the better. In fact, if one tightens them just enough so that when you turn the heli on its' side and shake it, the blades to not move. Then hover the heli and let the rotor stop on its' own. Do NOT stop the rotor with your hands. This will ensure the blades remain in their "in flight" lead/lag position in the blade grips.

Then tighten the blade bolts a bit more. Now you will have very little chance of having a blade/boom strike.

What causes most boom strikes, is the blades leading or lagging excessively through a change in rotor speed, while simultaneously giving a command that entails a lot of collective and/or cyclic pitch.

To understand this. While on the bench, move the blade in the grip to give about 20 degrees or so of lead or lag. Now rotate the head at zero pitch....the blades do not come close to the boom. Now do the same with full down collective. Rotate the head and see how your blades now contact the boom.

Phil

01-17-2017 07:07 PM
PM  EMAIL  GALLERY  Attn:RR
Dan Minick

Key Veteran

Columbus, WI

My Posts: All  Forum  Topic

I have been thinking about how you could actually measure this. Jogged my memory back to high school geometry.

http://ncalculators.com/number-conv...ras-theorem.htm

You know A and C, solve for B and cut your boom. Make sure you cut B a few MM longer than was needed

Team Synergy, Team FBL Rotors---Formerly Dyecocker1-------if its not broke...it will be!

01-18-2017 01:26 PM
PM  EMAIL  GALLERY  Attn:RR
Heli_Splatter

Key Veteran

Silver Spring, MD by way of Sidney, Ne - USA

My Posts: All  Forum  Topic

I checked my helicopters...stock Trex500 and 800 have about 1.5inches of horizontal space from main to tail blades. Maybe just me, but I would not overlap them. I really don't know how much coning I am getting and what a punchout would do.

I would love to watch some video of hard inverted punchouts when the blades are overlapping.

01-18-2017 06:48 PM
PM  EMAIL  GALLERY  Attn:RR
AirWolfRC

rrProfessor

42½ N, 83½ W

My Posts: All  Forum  Topic

Nothing complicated.

Measure the straight line distance from the center of the rotor head at the spindle to the center of the tail hub at the tail shaft.

That distance must be greater than half your rotor disk diameter plus half your tail disk diameter.

If you want to avoid boom strikes, keep your rotor speed up and/or don't punch out inverted too hard.

01-23-2017 01:06 AM
PM  EMAIL  HOMEPAGE  GALLERY  Attn:RR
Andy from Sandy

Key Veteran

Bedfordshire, UK

My Posts: All  Forum  Topic

I would imagine the flyer of a scale model will not be looking to punch out inverted.

To avoid a blade strike just make sure there is no overlap whatsoever and then they can never touch.

It was curious to me after a few years of flying my Logo 500 that I notice the blades overlap by quite a bit but they have never touched.

01-25-2017 05:29 PM
PM  EMAIL  GALLERY  Attn:RR
WATCH  1 page 645 views POST REPLY
ProModeler Scorpion Power
 Print TOPIC Advertisers 

 6  Topic Subscribe

Thursday, February 23 - 4:46 am - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies