SHUT OFF Les Réponses du questionnaires (5/04/2006)

Safety in F2D Combat
Summary and Evaluation of the Answers to the Questionnaire
We have received 57 answers from 22 countries including most of the countries with active
combat pilots. Many of the answers are from groups of people indicating that the views and
remarks represent at least 90 pilots and others engaged in this safety matter. Most answers give
remarks on almost all of the items in the questionnaire while a few only have opinions about the
shut-off. There are also suggestions of other things to do or to investigate more. These
suggestions can be found under the item Other.
In the questionnaire the introduction of a warning system was mentioned but not listed as a
separate item. Due to conformity reasons in this summary it has been included as an item of
itself.

Summary

Shut-off
An overwhelming majority of the answers are positive to the introduction of shut-offs provided
that they get a sufficient time both to learn how to handle them but also for developing them for
use with F2D models including how to start the reserve model when there is no line tension.
Answers from those used to shut-offs in other Combat classes indicate problems that need to be
solved.
Compared to a Fast Combat model and the type of shut-off used there the F2D model have less
line tension (as well in the air as at take-off), bell-cranks built into the wing, two models per heat
and matches that normally last for four minutes. Opinions also indicate that effort should be used
to investigate if there are other types of shut-offs that can be used instead of the types using line
tension.
Concerning the rules and how these should be formulated to deal with shut-offs and the different
types of situations that can occur have no clear indication from the answers. Matters to be dealt
with includes how to test the shut-off, what will happen if it not works at a line break (damaged
or not damaged by a midair collision), if it shut-off due to no or little line tension (but with the
lines intact), if the pilot cuts his own engine or if the engine is cut by a tactical move from the
opponent.

Increased line diameter
Everyone agrees on the fact that almost all kinds of lines can be cut by any propeller but that
thicker lines can keep together better in a line tangle. A majority are negative to an increased line
diameter as the lines would have higher weight therefore causing a need for more tip weight but
also for introducing new problems with less drag and more collisions/line tangles.

Decrease the power of the engine
The answers only gave remarks of the three suggestions we brought up to discussion with no
new ideas given. Many believe that changing the diameter of the venture is obsolete as this can’t
be done in an easy way on a lot of engine types. Introduce a minimum diameter of the propeller
would also cause problems as the engines normally are made to have a quite high rpm.
The easiest way due to the answers would be to decrease the output of the silencer. This will also
reduce the noise (but that is another matter!). The overall conclusion is that taking down the
speed of the model will take away the heart of the class as speed is one of the fascinating sides of
F2D.

Change the characteristics of the model
No one really believes that changing the models will have any influence on fly-aways. It is also
an economical matter as there are a lot of models in use.

Change the size of the engine
Almost no one believes this to be realistic due to the cost.

Increase the 150 N pull test of the lines
Divergent views among the answers. One group claim that it is ok to increase the pull test to 200
N as both carefully built models and proper lines easily will stand the test. Others claim that they
have to build new models. One answer indicates that an increased pull test can stress the lines
and damage them.
A majority are positive to a better visual inspection and giving the organiser a right to ask a
competitor to change the lines although they passed the pull test.

Quality of lines
Also divergent views. Some claim 4 strand lines to be better than 7 strand. Others claim the
opposite. Some claim that stainless steel lines should be banned and others that they should be
mandatory.
One of the answers suggests that effort should be made to look at new synthetically materials
and if they could be used as there are products on the market that may withstand cuts from a
propeller.
One answer propose that the lines should be “reinforced” or thicker where they are most likely to
break, i e near the handle or near the model.

Fuel. Change or delete the nitromethane content
Most answers says that deleting the nitromethane would make the engines both harder to start
and make them more critical for a good needle setting while a few have no objections to deleting
this component.
The common opinion seems that changing the nitromethane content will have no influence on
the number of fly-aways.
Having no nitromethane in the fuel makes it easy to test (with an indicator paper/stick) if
someone tries to cheat.

Reduce the radius of the centre circle
Also diverging opinions of this have any effect on the number of fly-aways although the majority
is saying they can accept a smaller pilot circle.

Install a safety net around the circle
Mostly positive answers to this question even if some answers put the finger on the fact that
regional contests will have an economical problem with nets/fences.
As an alternative to have a 3 or 5 meter high net around the flying circle (which would be the
best..) there are suggestions of fenced off spectator areas in addition to signs warning for flying
models. Another brilliant idea is to use the football goals as protective cages for time keepers,
other officials and spectators. Normally the contests are held at a football ground and the goals
will therefore be easily available without any costly investment.

Personal protection – Helmets
Most find it strange that not all people (Jury, Team Managers etc) being close to the circle are
mandated to wear helmets just like the pilots and the mechanics. A few claim that this should be
voluntary for the persons involved.

Introduction of a warning system
A lot of different views have come from the answers. Most agree on the fact that stricter
judgement to make the pilots abandon the rough flying style will have an influence on the
number of fly-aways. Opinion goes from using the current rules more strict and DQ everyone not
behaving at once to introducing a warning system with yellow and red cards.
Some suggests that both pilots should be disqualified if there is a fly-away while others leave it
to the discretion of the Jury to punish one or both of the pilots with a DQ in case of a fly-away.
Another suggestion is not to give a refly to a pilot that is on the way of loosing at the time of the
fly-away as this will prevent loosing pilots from using a fly-away to get a refly. Another thing to
do would to ask both pilots to land when a line tangle occurs (maybe also stop the watches and
continue the match after untangling….).

Other
Here you will find a short summary of different views mentioned in all the answers.
Most answers express a worry that hastily taken rule changes might ruin combat. As the problem
with fly-aways have existed for many years (and not increased and not caused any serious
accidents so far) they don’t see the need for a quick decision instead of well thought-off rule
changes. The problem with fly-aways can be divided into two parts where one is how to make it
safer when a fly-away occurs and the other of how to minimize fly-aways (we can never
eliminate them!).
To make it safer when a fly-away occurs one can use shut-offs, net or fence at the contest site
and helmets for all involved. A hemispherical net around and above the circle would naturally be
the best but this is not feasible due to costs. Also a net around the circle would cause high costs
(although you have it in T/R and Speed without protests).
A better way to go would be to have fenced off areas for spectators etc in combination with shutoffs.
As pointed out there is still a lot of work to do before shut-offs can be used in F2D. Not to
forget is the fact that a shut-off will take about 2 seconds to cut and that the model will travel at
least 40 meters in this time. Therefore people near the circle must be protected in other ways as
the shut-off will have a small or none effect in this area.
The general opinion is that changing characteristics of the engine, lines or model will have small
or no effect on the number of fly-aways. Some answers implicates that new problems can be
brought into F2D with if some of these changes will become reality. The most effective way
seems to get pilots to change tactics and use a “cleaner” flying style. This can be achieved by
stricter rules and by stricter judgement from the Jury.
One opinion express that introducing shut-offs will have a huge influence of making F2D more
complicated and reduce the number of competitors in the class, also making it more difficult for
new pilots to enter. A comparison is made with what happened in the USA when shut-offs where
introduced. Instead it is proposed to change to smaller models and an engine size of 1.5 cm3 as
these models will have a smaller mass and a lower speed thereby making it safer without the
need of a shut-off.
One idea suggests the use of one or more horns. When dangerous situations occurs in the bout
someone will blow the horn indicating to people around the circle to be alert as a model can
come loose.
Another thing that should be addressed is the increased tactics to use people standing outside the
circle signalling to the flying pilot that he is on his way to loose and therefore need to “take out”
his opponent either by a crash or a fly-away. This is unsportsmanlike behaviour and should be
dealt with.
To make it easier for the Jury to make decisions an official video could be used.
One answer put the finger on the fact that many pilots use an open-loop safety strap at the handle
instead of a self-locking construction as shown in the rules. This open-loop system can in some
situations cause pilots to drop the handle (and model) as it opens up.
One answer likes the rules to be simpler and that the power of the Jury should be reduced.
Also that the increased cost should be considered as there are a lot of people who might not
afford to continue or start with combat if models become more complicated with shut-offs etc.


Evaluation (57 answers from 22 countries representing +90 persons)

Shut-off
41 answers more or less agree to a shut-off rule but states that enough time must be
given to develop them before an introduction. There is a clear indication that it will
not work just by using the Fast Combat shut-offs. Effort should be put into the
question if there are other constructions that can be used. Great consideration
should be taken when writing the rules dealing with situations that can occur when
using shut-offs. An acceptable date for mandatory shut-offs seems to be for the
World Champs in 2008 (1st of January 2008).
11 answers says no to shut-offs. Arguments are that they complicate things, don’t
work well enough or just will cause problems.
5 answers express no opinion.

Increased line diameter
24 answers are negative to increase the line diameter in. One argument is that it
would introduce new problems like less line tension etc.
21 answers are positive to increase the line diameter in. Some answers suspect
other problems to be introduced. Even a plastic prop will cut thicker lines but
thicker lines will stay together better in a line tangle.
12 answers express no opinion in.

Decrease the power of the engine
18 answers don’t want any changes at all. They claim that these changes will have
no effect at all regarding fly-aways.
2 answers are positive to an overall change.
2 answers are positive to change the venture diameter.
5 answers are positive to have a minimum propeller diameter.
1 answer would like pressure tanks to be prohibited.
2 answers just express the opinion to slow down the speed of the model.
10 answers are positive to reduce the outlet of the silencer. It is pointed out that this
also will reduce the noise.
18 answers express no opinion.

Change the characteristics of the model
32 answers are negative to any changes at all. They claim that these changes will
have no effect at all regarding fly-aways. There is also an economical matter if
models become obsolete.
2 answers are positive to changes.
23 answers express no opinion.

Change the size of the engine
33 answers are negative to change the size of the engine. One argument is that it
isn’t realistic due to the cost involved.
1 answer says maybe……..
1 answer is positive to a change.
22 answers express no opinion.

Increase the 150 N pull test of the lines
23 answers are positive to an increased pull test. Arguments are that both the
models and the lines easily could stand a higher pull test and that bad lines will be
sorted out.
10 answers are positive to stricter inspection.
11 answers don’t like any changes in the pull test. Arguments are that new models
have to be built and it could stress the lines (damage them).
21 answers express no opinion.

Quality of lines
Very diverging opinions.
10 answers prefer a change to higher demands on the lines.
9 answers indicate that more effort must be made to find out the best material or
type. Even look at other materials as synthetically ones.
8 answers prefer no change at all.
5 answers prefer 4 strand to 7 strand.
1 answeer prefer 7 strand to 4 strand.
24 answers express no opinion.

Fuel. Change or delete the nitromethane content
22 answers would like to keep the fuel as it is. Deleting it will have little influence
on the flying speed but make the engines harder to start and more critical on the
setting.
5 answers want to delete the nitromethane. It will make the fuel cheaper and one
(poisonous) component less to handle.
2 answers want to reduce the amount to 5%.
28 answers express no opinion.

Reduce the radius of the centre circle
20 answers are positive to reduce the radius of the flying circle.
13 answers are negative to a change.
24 answers express no opinion.

Install a safety net around the circle
22 answers are positive to have some sort of net/fence at the contest site. If not
around all of the circle so at least a partial one for spectators.
7 answers are negative to have net or fences. One argument is that it would
increase the cost for the organizer, especially at regional contests.
28 answers express no opinion.

Personal protection – Helmets
24 answers think that helmets should be mandatory for all people around the
circle.
5 answers are negative to a rule and think it should be voluntary.
28 answers express no opinion.
One answer wants Ice-hockey helmets to be banned as they are unsafe.

Introduction of a warning system
14 answers are positive to some sort of a warning system. There are also an opinion
that there should be a more strict judgement against pilots with a rough flying style.
5 answers are negative to a warning system.
2 answers express an opinion that it will have no influence to decrease the number
of fly-aways.
36 answers express no opinion.