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HelicopterMain Discussion › Landing Struts / Gears (Why lean back?)
11-27-2006 01:41 AM  11 years agoPost 21
asong26

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VA

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Actually, I was out of town. I've heard everyone had a great time.

Andrew

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11-27-2006 01:50 AM  11 years agoPost 22
ch53e

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Forest, Virginia / So. Cal. Native

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sorry you missed it .. it was alot of fun. Everyone I met was really nice, flew safely and no crashes. You have a great bunch of guys up there.

Align Trex 450SE
Align Trex 600CF
TwinnRexx

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11-27-2006 02:06 AM  11 years agoPost 23
red_z06

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Dumont, NJ

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Hey guys:

It is ok to guess at stuff but it would be good to find out why an engineer designed it that way.

In most cases helis do not stop and descend vertically. They do carry small forward and vertical speed when they touchdown. Although you can descend vertically, the chance of carrying small forward velocity is far greater than reverse velocity.

At the point of contact, there are two components of forces present.

one is force normal (90deg) to ground which equals resulting vertical force (weight minus rotor thrust)

two is the force parallel to ground which is typically called frictional force.

When these two vectors are combined, the resultant vector is slanted and the angle resemble that of landing gear struts.

When the strut angle line up with the force vector at contact, the struts properly do the designed task of providing cushion.

However, if they do not match and the load becomes greater, the contact with the ground generates twisting force called torque. This torque applies load directly on the strut anchor point.

In real aircraft, components are designed to survive required load and no more. As you already know, excess weight means loss of performance.

However, model helis fall under entirely different category. They can withstand way more load that required for landing and survive actual crash sometimes.

For this reason, the strut angle carries no real meaning other than asthetics.

www.JustinJee.com

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11-27-2006 02:22 AM  11 years agoPost 24
asong26

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red_z06:

What you just said makes perfect sense. I now understand why the manual tells us to mount the struts leaning backwards. Wealth of knowledge there

So, based on what you're saying, for our purposes, it doesn't really matter?

Also, since you said weight is a factor in this case, i would have to like to ask: At what weight does this become an issue? My gasser@ full tank is around 13 - 14 pounds...

Andrew

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11-27-2006 02:22 AM  11 years agoPost 25
alvinrc

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Mobile, AL, USA

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On A Raptor Titan:
The nonstock strut direction looks better to me.
Also, if the CG is on the main shaft it is very close to being above the rear strut if assembled as instructions show.
Turning the struts around will allow the Chopper CG to be more toward the front strut allowing it to carry more of it's share of the weight.

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11-27-2006 02:31 AM  11 years agoPost 26
AirWolfRC

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And VERY FEW people do run-on landings.

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11-27-2006 02:44 AM  11 years agoPost 27
red_z06

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Dumont, NJ

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Unlike pure science like physics, engineering is an inexact science. This is because there is no such thing as perfect answer. It is always a compromise between many design goals. The slant angle also is not an absolute solution. It is merely an optimized solution to many possible senarios.

BTW, optimized in aerospace terms mean least material that can survive the load.

Slant forward design can afford much greater acceptable landing speed in both vertical and forward. Obviousely, non slanted struts of same spec will withstand greatest vertical force but is much weaker in the event of even minute (barely detectable) forward velocity.

In a semi abrupt survivable landing (semi uncontrolled), chance of having forward velocity is far greater than most controlled landing. This is what the struts are designed to withstand.

www.JustinJee.com

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11-27-2006 02:57 AM  11 years agoPost 28
asong26

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VA

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Well put. I guess it all depends on what you have and how you're using it.

I, for one am going to put the struts leading forward. It really does make the heli look like hauling a*! forward. I'll just need to carefully adjust the skid position to find that CG at around half tank weight. My predator's gas tank is at the very front, so when the tank is 1/3, then heli begins to lean backwards.

Thank you everyone for providing your input.

Andrew

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11-27-2006 10:03 AM  11 years agoPost 29
PaulJC

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Hertfordshire UK

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And VERY FEW people do run-on landings
But lots of people do nice bouncy sliding autos

Re-entering the atmosphere...

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11-27-2006 03:21 PM  11 years agoPost 30
asong26

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VA

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Forget the fancy stuff. Any landing below the blades are good for me. You know the landing style that doesn't have the main blade, flybar and boom flying off of it?

Andrew

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11-27-2006 03:23 PM  11 years agoPost 31
red_z06

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Dumont, NJ

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As I stated, RC heli strut direction is for asthetic purposes only so do as you will.

www.JustinJee.com

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11-27-2006 07:06 PM  11 years agoPost 32
leejax01

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Jax. Fl.

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I always liked mine facing/slanting forward and I can adjust the skids forward or backward until the balance is what I want. To me it was cosmetic, but it was harder to tilt it back to the tail with them facing forward. I just checked my gallery and all the helis were facing forward.

Perfect practice makes perfect

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11-27-2006 08:23 PM  11 years agoPost 33
asong26

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VA

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I've just switched mine to face forward, and adjusted the skids to make sure both forward and backward lean is minimized.

I like this look much much better!

Andrew

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12-01-2006 05:06 PM  11 years agoPost 34
AH-1 pilot

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Tampa, Florida

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gear
With the 'TOP'of the gear slanted forward, more weight is shifted forward of the pivot point (rear skid tubes)....now, more force is required to push the tail down. This helps keep the blades from hitting grass etc..as much.

Michael

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HelicopterMain Discussion › Landing Struts / Gears (Why lean back?)
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