Since hearing proposals into this direction at last year's WCh, I extensively explained to anybody that even with brake electric motors won't come to a full stop unless they're flown very slow. So trying to impose a fully stopped prop onto us would effectively ban electrics from F2B.

Yet they (electro haters/nitwits) did it to us: 

F2 Subcommittee    4.2.15.17 Landing Manoeuvre
Clarify power-off definition, page 28:
g) Start of manoeuvre: as the model aircraft leaves a height of 1.5 metres, plus/minus 30 cm, and with the motor/s and propeller/s stopped (gliding flight)
h.) The descent segment: the model aircraft should fly for 1 full gliding lap (power off condition with the motor/s and propeller/s stopped), measured from the start of the descent at the 1.5 metres plus/minus 30 cm height, until the point of touchdown.

The brake slows the prop to about 1-3 revs p. sec and by the time it has finally stopped, the plane has not enough speed left to complete the full lap till touchdown.

This rule change must have been made on purpose only to aggravate electric flyers or it was done out of complete ignorance.

I don't see this as a problem........

I believe both Schulze and Castle Creations are making ESC's that will allow the governor to be used in conjunction with the brake.

If Schulze or CC doesn't come through for us, there are many EE's that are very capable of coming up with something.

That is what I mean by "I don't see this as a problem". Sorry for the confusion.

Mike

Bruno, are you sure you have the brake for full effect? I use folding prop, but never had problems to fold it at landing, may be really not immediatelly.

Reason for brake is to show judges that the motor is in real power off mode, not little slower, not slowly deccelerating, but clearly not giving any power at all. You are right, tah allowing some minimal speed (few rpm/s) we could allow. But in any case, landing with spopped prop is far far easier than free spinning prop and beleive me, landing with folded prop is pleasure. 

Bruno,
   I know what you mean about a mechanical brake, and I agree!!!

   You said "the brake never stops the prop entirely". Do you mean the brake stops the prop and it spins up from airflow, or it really does not stop the prop? The brake on a CC ESC can bring the prop to a stop if that is the case.

   For some reason I remember the brake stopping my prop entirely (and the prop didn't spin up from airflow). Maybe it is because I use less pitch than you? I think lower pitch props would be less likely to spin from airflow. It may also be possible that my motor has more cogging effect than yours. I believe you are using Plettenberg also, so that may not be the case either. (I could be mistaken, it's been a few months since I have flown). 



   

   You said "the brake never stops the prop entirely". Do you mean the brake stops the prop and it spins up from airflow, or it really does not stop the prop?

The latter, it brakes strongly (in under 2 sec)  but leaves the prop turning v e r y slow, ~3 r p sec.
After timer cuts out, I do my 'dive to level' from ~45deg to hit level right in front of the judges and having sufficient speed to glide a full lap till touchdown. Wouldn't be possible without a brake. Then somewhere during that lap the prop comes to a standstill.
I found that Bob's Genesis (without a brake) suffered a lot less from the spinning prop than the Blue Pearl (the WCh/Test plane Henk de Jong and I converted) Under power both planes were eerily similar in feel.

The brake on a CC ESC can bring the prop to a stop if that is the case.

But you weren't using governor, were you?

 For some reason I remember the brake stopping my prop entirely (and the prop didn't spin up from airflow). Maybe it is because I use less pitch than you? I think lower pitch props would be less likely to spin from airflow. It may also be possible that my motor has more cogging effect than yours. I believe you are using Plettenberg also, so that may not be the case either. (I could be mistaken, it's been a few months since I have flown).

I fly a AXI 2826-10 with a Graupner 12x6 el. prop.  Like said I'm using 6" and I even tend to go to more pitch and less revs to load the governor more.
We found we had a 400->800 Watt kick when suddenly loading the prop. The CC took it without blinking, the Kontronik (you could hear the revs drop for a split second) really lagged so much that it never could cope with a good corner, hence the need for kicking up revs with 2 % before the square eights.... Maybe the brake also suffers from this 'safety' that heli's might need. Or is it to prevent claims from dumb***ses that keep stripping the gears on their choppers?
What I need apparently, is new software for my CC-45 to make the brake combine with governor.... But they wouldn't do that for me last year when I asked So that's why I changed to Kontronik...

Hi Bruno,
I thought this issue was dead after the jury rendered its pre-emptive interpretation last year."
This is certainly annoying, but in my opinion, not disastrous. We will come up with a brake that first stops" and then energises one phase at a limited current to add more resistance. I think that will do the job.
As elegant as the mechanical brake was in your airplane, this is a pain in the you-know-what. You were in Valladolid ... you too Igor, did you hear some group of neo-Luddites crying for a return to "real" powerplants?

It is time to write or call your local member of the technical sub-committee and politely offer to rip their flying arm off.

We shall overcome!

>>>crying for a return to "real" powerplants?<<<
Some people want to keep IC engines just because they believe that it is that "proper" powertrain for stunt (and I tend to agree that it is ), and some people need to fly electric because of "green" problems or any other very good reasons, or they just like it.

I just like it better: no liquid fuel is a huge improvement in my opinion. I also like the possibility to be able to hear my coach while flying. And from the start power was at least 'good enough' Shure, I'd like a bit more of this or that, but it works OK.

Peter Germann is right, he means that we have enough ways how to keep good balance in rules to make them comparable (in my eyes electric is disadvantage so for example allowing of governor can make it competitive back and so on).

Governor mode was allowed from the start on.  But specifying a standing prop in the rules is putting up a new obstacle. 'No power' would have been enough. Haven't had any complaints from judges not being able to determine if my motor's power was off. Difference between 9800 rpm and 3 rpsec is very visible...

I do not see big problems here.

But I do, first hand.... Now I'll have to do extra work on other aspects than the powercharacteristics of the set-up. I feel like being forced to throw away time on something useless.

I am from Almere, near Amsterdam.

Henk and I were out yesterday morning sorting out some trim.
Unfortunately I'll be working during the day this weekend.
I wanted to go flying with Henk and do some trimming the Sunday afternoon, but it's very unlikely now.
Also because of the wind strenght and direction. We're on a RC field and the spot were we can fly during the weekend is too turbulent over 4 m/sec between N & E.
Sorting out trim is useless (and even dangerous) in those circumstances....

I have asked one of my buddies, who lives in Limburg - between where you are now and Genk-, if he'd go out flying indoor CL.
He started flying CL again after seeing your first videos.
When I hear from him, I'll let you know...

Great, do you know that also Salvatore tries to do indoor?

Yes, I pushed your videos on various (mainly RC) forums in the Dutch language and one of the guys in the South picked it up and he is really flying now. No aerobatics yet, but he'll learn. He incidently met Sal at the indoor meeting of the Genk club and that's how Sal got interested. I talked to him on the phone last Tuesday about the Genk 2007 contest.

... btw what you plan to do next winter? 

You don't wish to know...
This  :

Hi Gang,
If the rules do not change from what is proposed now, we have a few alternatives.

As Igor points out, there is the cogging torque which also helps hold the prop still.
Some motors have more, others less, and there is no simple answer to which is better.
The braking torque is proportional to the RPM, so at the moment that the prop stops, that torque goes to zero.
If the cogging torque is inadequate ...

The ESC manufacturers could add what looks like cogging torque by energizing one winding at some moderate current (controlled by turning the current on and off quickly at some pre-determined duty-cycle) after the prop has nearly stopped. We will see if any respond.

Otherwise, could you post some of those servo-operated brake photos, Bruno?

have fun,
         Dean

Go looking in the electronics surplus sites for stepping motors with built in brakes.  They are used in applications where the mechanism they are driving could cause a non-braked motor to turn just from inertia or weight.  They use a fairly simple solenoid mechanism that releases the break when the motor coils are energized.

On another forum the "Anti-Electric" brigade were getting quite hysterical! Just about as bad as the "Anti-Arf" crowd. 

As to stopping the prop - the simple solution (EE wise) is to put a little DC (direct current) through 2 windings of the motor. In full size engineering this is known as "plugging". It should be relatively easy for the brushless controller makers to introduce this. But you only need a little current - if you put put the full battery voltage across the windings they would burn up very fast indeed.

Not so easy but equally effective is to short two of the windings. If you try that on a brushless motor you will see that it's very difficult to turn the shaft.

This is something to think about.

PS
I would not put it past the IC fanatics to have deliberately put in the "stopped prop" clause. Some are so self-centred they cannot think beyond themselves to the general good of the sport / hobby. I am looking forward to my first electric C/L plane - BECAUSE I CAN THEN FLY NEAR MY HOUSE! Now, it's a 19 mile trip either way to the field. NOISE is indeed the problem.

Charles

The simple solution is to have an "Electric Only" event with it's own rules.