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Category: Archive 2009
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Table of Contents SEN 1302

 

  1.  Watt's Up with Q
  2. Anselmo Update
  3. F1Q or how big is your Prop

 

 

 

 Watt's up with Q

 Klaus W. Salzer wrote:

Another clear indication that the rules in F1Q have to be changed ... how
is still not clear!
 

In SEN 1301 Klaus brought up again the question of F1Q power limitation. I totally agree with him, that the current rules allow the models to be ridiculously over-powered, with people using motor runs below 10 seconds, while 20 seconds would be allowed! I think everyone sees, that a major change in the rules is to be expected, and while that statement is written on the wall, it puts many people off, delaying them from trying their hands on F1Q. I can tell you that surely it puts me off; I am most interested in the class, but do not find it reasonable to to invest time and money, while all the effort will be in vain in a year or two.

So, while CIAM seems to be unable to take any action in this matter, I suggest an open discussion and hopefully an agreement on a limited set of rules for F1Q. These rules could then be applied as an unofficial subclass for F1Q in some contests (like Nordic, Baltic etc.), and if the "limited" set of rules shows to be working, they could be then presented to the CIAM as a new, but tested proposal for the F1Q rules.

What should the limited rules then be like? In my view, the power should be restricted to a level where a spiral climb of 15 to 20 seconds is required. F1C has shown, that over-powered models and reduction of motor run will lead into rather dangerous models, that are indifferent in stability and very sensitive to launch errors. A slower spiral climb requires the model to be stable, and therefore it will be able to correct some error or bias in the climb attitude.

The big question is now, how to limit the power? I do NOT think that electric devices, such as "black box" current limiters or energy timers are the solution. It is rather difficult to verify, whether these work as they should. It requires good quality electronic measuring devices, and some expertese to use them. The same applies also to the concept of serial resistor limiting the current to the motor (my previous pet idea). However, I recently learned that an RC soaring club "Albuquerque Soaring Association" has for a few years applied a set of rules to limit the power of their models, that is rather straightforward and easy to verify. The rules say:

       "Motors are restricted to out runner type without gearboxes. The maximum size of the flux ring is 28 mm in diameter and 16 mm in length. Batteries are restricted to 7 Nicd / Nimh or 2 lithium polymer cells."

Thus the rules are straightforward, and it is easy to verify with simple calibers, that the motor is within the restrictions. But most of all, the beauty of the rules is that restricting the motor size quite efficiently restricts the maximum (output) power of the motor. If you want to "push" the motor by using larger prop than is the most efficient, you indeed can increase the current to the motor, but that makes the efficiency of the motor crash, and out output power does not increase.

The ASA rules have resulted in Hacker A20-20L being the most widely used motor, and that can draw up to 20A of current, which means around 150 watts of input power (remember the 2-cell restriction!), and some 120 to 130 watts of output power. That might be quite sufficient for a A2-sized F1Q, maybe too much for smaller models.



-Tapio-

Anselmo Update

All
Pim Ruyter has sent the following message about Anselmo Zeri.
Peter
Hereby the latest news about Anselmo.
As you already know there have been two cancers in his brain discovered a larger and a small one the left side.  
The larger can be operated, a renown brain surgeon will operate but it is not decided yet where or when, probably next week.
The smaller tumor is to small to be operated and will be treated with radiation. 
The speech problems he had are cured, it was caused by fluid around the tumor causing pressure on the speech part of his brain. Medical treatment has removed the fluid. Anselmo is no longer in hospital last night I had a long talk with his daughter and a brief with Anselmo. I will visit Anselmo next Thursday.
Brain surgery is delicate and there will be always a risk.
Anyone who like to send a card here is his address.
Anselmo Zeri
De Colman 21 
2291 JK Wateringen 
Netherlands
Best regards,
Pim Ruyter


F1Q or how big is your prop?


“Those big guys are beating me – so let’s change the F1Q rules!”

 

Based on FFn 0905, "Thoughts about F1Q" by Andreas Lindner, the biggest difference

across F1Q models is their prop size.  The models with largest props (Assmuss 12"; 

Lidner 13-14"; Schlosberg 16“; Richter 12") also weigh 600+ grams. Their common

feature is that they are trimmed to fly straight, and anything can happen after 10

seconds – as they lack cross controls. These models draw up to 300 Wattsstatically.

 

Models with smaller props (Amotor 9"; Hasse 11"; Ruyter 12"?; Schmidtutz 10";

Trumpf 11") are generally lighter models, trimmed  to climb in a right spiral. Almost all

the American F1Q and B-electric models fall into this category. These models draw

in the low 200 Watts Statically.

 

So one can build either type of model. The large propellormodels are notoriously

difficult to trim but, as Klaus Salzer aptly points out, they hold a clear advantage in

the flyoffs.

 

So what can be done? It seems that the most promising approach is to eventually

move towards motor runs defined by work, or Joules - Watts x seconds.  The easiest

way is to measure the static Wattage input with the motor at full power using a

Wattmeter. (One can measure output Wattage, but this requires standard props and

conversion tables).

 

So given two models, say one with 200 Watts, the other with 300 Watts, then if the

first is flying a 15 seconds motor runs, or using 3000 Joules, the second should fly

10 seconds motor runs to use the same Input “work”. Then, when motor runs are cut

to 5 seconds for the first model, the second models would only have a 3.33 seconds

motor run. The big propellor guys are now properlyhandicapped.

 

But wait! a “3.33 second motor run?” The unusual motor runs can be set by e-timers,

and each model couldhave a posted factor (in percentage, say 66.6% relative to the

"standard" 200 Watts model). On the other hand, models with less than 200 Watts

input will not be granted longer motor runs. (Otherwise a model with 100 Watts input

will get 30 seconds motor runs.)

 

Aram   

.....

Roger Morrell

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