RunRyder RC
 2  Topic Subscribe
WATCH
 1 page 1318 views
Scorpion Power Scorpion Power
HelicopterAerobatic FAI F3C F3N Contest › Intrepretation of FAI F3C Regulations
09-10-2007 03:41 PM  10 years agoPost 1
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

Hello,
First, I'll admit to being a total "newbie" when it comes to really looking at the F3C regulations and have no background on why certain things "are the way they are." I have a couple questions about the interpretation of the regulations which I'm hoping those more seasoned in F3C can help me with.

The regulations contain the following wording with regards to gyros:
"GYROS: The use of automatic stabilisation devices that utilise external references is forbidden. The use of pre-programmed flight manoeuvres is forbidden. The use of an electronic rate sensor is limited to rotation about the yaw axis."

It clearly states "rate sensor" for the yaw axis only. Yet heading hold gyros are being used which would seem to violate the regulations. Could someone help me with this one?

Further if one really wants to break down the rules, let's take a look at the wording with respect to flybarless systems. The first sentence says "that utilise external references." Well, the flybarless systems I'm thinking of do not use an external reference (CSM, V-Bar/V-Stabi).

The second sentence is fine and I totally agree with that for now and the future.

The third sentence states "rate sensor." What is the definition of a "sensor"? Is it the physics being used within a device/part, is it the output of the sensor device/part, or is it a unit as a whole such as a gyro? What is a "rate sensor"? Is it the rate of acceleration, angular rate/velocity, etc.? Seems to leave a lot of room for interpretation.

My other quandary is about the weight limits. Why do liquid fuel powered helis have a 6 kg limit without fuel yet electrics are limited to 6 kg with "fuel"? Wouldn’t it be more “fair” to limit electrics to perhaps the average of 6 kg and the weight of the typical liquid fuel competition heli (that meets the 6 kg dry limit) full of fuel?

Any help on these issues would be appreciated.

Thank you,
John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
09-10-2007 04:33 PM  10 years agoPost 2
RotarSoft

rrVeteran

St Leonards On Sea​UK

My Posts: All  Forum  Topic

John,

Regarding the "rate sensor"..

This does allow Heading Hold gyros as these are still rate gyros.

What it is trying to get at is that whatever stabalisation device you use to help control the tail must not use external referencess such as visual or magnetic readings from sources external to the machine.

The gyro on the tail must only respond to rates of changes that are measured directly on the airframe.

Heading Hold gyros still only measure the rate of rotation of the machine.. it is just the clever algorithms that differentiate them from our older non heading hold gyros.. they are still using the same sensing devices.

I hope I've explained that clearly.. but probably not!

The flybarless systems you are thinking of do not use external references (unlike the co-pilot) and that is fine.. but you are only allowed a stabilisation sensor on Yaw.. so flybarless is a no no for now..

"Rate sensor" is as you suggest.. interpret to be what you want.. so long as it is not relying on "external" sources then you are fine.. so an accelerometer is ok.. but something like an IR sensor would not be allowed..

Regarding the weight issue.. you may have a point.. however you would never want your machine to be knocking on 6kg as it would fly like a dog for the blade area we are limited to!

Cheers

Mark

PM  EMAIL  GALLERY  Attn:RR  Quote
09-10-2007 05:31 PM  10 years agoPost 3
JKos

rrProfessor

Redondo Beach, CA

My Posts: All  Forum  Topic

> however you would never want your machine to be knocking on 6kg as
> it would fly like a dog for the blade area we are limited to!

Good point as 6 kg is 13.2 lbs. Although, my Predator Gasser flew extrememly well at around that weight with 710 blades.

Thanks,
John

RR rules!

PM  EMAIL  GALLERY  Attn:RR  Quote
09-10-2007 05:44 PM  10 years agoPost 4
RotarSoft

rrVeteran

St Leonards On Sea​UK

My Posts: All  Forum  Topic

John,

I doubt you were trying to pull of some of the maneuvers the F3C schedule demands.. especially in a strong cross wind.. thats when the power to weight ratio really shows up!

Weight is good up to a point. For example an 8lb 90 size model would hover awfully in a strong wind where as your Predator gasser would be great.. this in danger of going off topic so I shall stop here!

Cheers

Mark

PM  EMAIL  GALLERY  Attn:RR  Quote
WATCH
 1 page 1318 views
Scorpion Power Scorpion Power
HelicopterAerobatic FAI F3C F3N Contest › Intrepretation of FAI F3C Regulations
 Print TOPIC  Make Suggestion 

 2  Topic Subscribe

Monday, November 20 - 11:55 am - Copyright © 2000-2017 RunRyder   EMAILEnable Cookies

Login Here
 New Subscriptions 
 Buddies Online