National Free Flight Society

SEN 1924

SEN 1924 – Table of Contents

  1. Q on FB
  2. Missing SEN Issues

Q on FB – editorial

There is a F1Q group on Facebook where there has been a very active discussion around F1Q going over a number of key issues. These issues are summarized here and them followed by a slightly edited transcript of the FB discussion. It is important to thinks about these items before the up coming FAI meetings.

F1Q was originally conceived as an open class where you could have a short powerful motor run or a long slow one depending on your preference. Now some people think that class should F1C-like with a short power run, other F1B-like with a longer motor , these can be achieved by changing the rules (yet again) limit the length of the motor run as well as the energy allocation . There are others than think messing with the rules again will further discourage participation and delay the possible inclusion of F1Q in the World Champs.

There are some comparisons between F1Q and the popular E-36 class developed in the USA by the NFFS. There are very clearly 2 things the NFFS did right – first was getting some experienced modelers build and fly prototypes to make certain they were practical and second was not fiddling with the rules each year. One major concern with electric power is how to stop someone with a very expensive battery and/or motor from dominating the class. The F1Q approach was to use an energy limiter device similar to that used in some FAI R/C classes. The E-36 class limits the performance by restricting the moveable control surfaces making hard to use excessive power. The risk with the E-36 approach is that you could end up with a F1P situation where you need a special fly off model or have knife edge trim that is very hard to manage. This has not manifested itself in practice and the E-36 class have proved very popular on the field.

Last year there was a proposal to create a FAF FF mini-event F1S based on E-36, this proposal was withdrawn for some inexplicable or un explained reason. E-36 or F1S is a small model class that can be flown on smaller that the F1ABCQ models and costs less than the big classes. With shrinking flying fields and participation a small field, lower cost class seems like a no-brainer. There is a lot of interest in E-36 world wide. In the USA the typical AMA prefers not to fly in rounds while US FAI flyer prefer rounds but this is not really an issue as long as the model specs are kept in line. It would give more event to use the E-36/F1S model.

F1Q on FB transcript 

(some non-English entries removed and other minor editing)

Matti Lihtamo
The year 2015 rules will make F1Q class of electric Wakefield class. I think the FAI Free Flight do not need second Wakefield class.
Electric Power class would the need. This could replace after a few years F1C class.
This is achieved by a simple change in the rule, the maximum the motor running time of 10 sec.

Dietrich Sauter The new rule forced me to change my model concept. Until yet I had 7 sec Motor run.
Now I develop a model with arround 30 sec Motor run. But the challange is the same. High efficient components.
I expect more high by using same amount of energy in spiral 30 sec climb instead of straight up.
After several changes in that class I hope for a constant rule. Because otherwise I can not catch up because buiding needs time.

Pim Ruyter I agree with Dietrich! I stopped flying F1Q 3-4 years ago until the ruling is stabilised, I am still waiting.
If the ruling conitunue to change as fast like now the F1Q class will be a dead born class before maturity.

Tapio Linkosalo Agreed. There seems to be an idea behind the rulemaking, that F1Q rules should be as open as possible,
to allow many different approaches. Personally I doubt that this works, but models will eventually converge towards one optimum
(as they tend to do in all other classes). Personally I also agree with Matti that F1Q should be developed towards a safer and
quieter power model that would eventually replace F1C...

Mar Ci Im really disappointed about all these maybe crazy discussions about the new rules here and at the
NFFS forum before the season 2015 even starts. In my opinion the changes are okay.
They will decrease the maximum heights and allow to test many different model concepts.
Some may prefer a high power concept and some a low power(maybe a low cost concept too?).
No one is really forced to use the maximum motor running time.
Only the decrease of the maximum weight for the energy calculation is a way to much.

Matti Lihtamo Good (light weight and aerodynamically good) model is a high performance in all sorts of rules.
The same F1Q model, which vertical climb fine, climb to a higher 40 s spiral.
So next year we will see only the "electric wakefield" model class F1Q. Goodbye Power F1Q!

Don DeLoach Replace F1Q with USA E-36. Simple rules, simple models, very fun!

Don DeLoach What is the rule change? Dropping from 5 joules to 4?

Tapio Linkosalo E-36 sounds like fun! Too bad the FAI dropped F1S: Limiting the power not by power measures but by
limiting possible trim changes sounds like an interesting alternative....

Mar Ci Anyway.... I would prefer testing model concepts with the new rule instead of writing romans on FB or a forum.

Tapio Linkosalo Writing romans (or novels) is much less effort than actually testing things in real life!

But seriously I think we should first agree what we want for F1Q, and then start to making a rules set that achieves the goal.
At current, the goal is quite diverge - some prefer power models, some feel that any approach should qualify, some feel that the
power should be measured (and limited) as itself, while others consider intermittent ways of limiting power sufficient.
While there is no consensus on aim, there cannot bean agreement on the wording of the rules....

Matti Lihtamo I agree with Tapio, that we hobbyists need to decide what sort of class we want to F1Q,
10 s vertical climb or 40 s spiral climb. This class is the issue the competition.
The rules will always control the development of to one extreme direction, the next year 40 s spiral climb.
Is it this good? We are now in face a choice that is difficult to come back. I am asking opinions on 10 s / 40 s!

Mar Ci I think we all should log some heights and compare it!! Me and my father tested many different ways
from 12s spiral up to 40s spiral climb. Result - always the same heights! So I guess with a 500g
model and 5-7s vertical climb you will increase the maximum height compared to spiral climb because of the additional bunt
height like in F1A. For us: the choice which way of climbing and even the difference on spiral climb (12 up to 40s) depends on
the individual affinity of the pilot or on tactical/weather-related reasons.
But I'm really sure every concept has the same chance in season 2015!
I was so happy at the german champion-ships this year to see so many different models and concepts and all
together at the same class with the same chances to win.
I don't want a class where nearly everyone got a model from Stefanchuk or someone else.
Next thing I cant understand - F1Q is always in comparison with F1B and F1C.
It would be cool to see this class as an independent class on its own with a high variety of model concepts.
Thats why its ridiculous that a electric copy of F1C is great and a "electric wakefield" is bad.
Did someone a online survey to proof this?
We should concentrate on the important things Ron Aßmuß said:
Everyone has to got a energy-limiter in his or her model.
Thats the only way to check and regulate the energy consumption. Different accu temp.
and profile conditions make it impossible to compare a ground check with the consumed energy during the flight.
And thats not fair! With a energy limiter on every model its no problem anymore.
Even the costs are non essential. If someone has the money to take part on many world cups he got the money for a 40-80€ limiter too!

Tapio Linkosalo Ok, two comments: I'm not so surprised that any climb time results in the same altitude - after all you are using
the same energy budget for climb. Fast climb has the gain of not having to waste energy to wing lift (to produce stable spiral),
but then faster speed means more drag, so you need a cleaner model, whereas the slow spiral climb model can be more optimized for
glide efficiency. I agree that for a fast model you can use the kinetic energy and bunt to gain some extra height,
but then a model that climbs in a 40 seconds spiral spends half a minute more _flight_ time in the climb - that is also some advantage.

about limiters - i agree that the price is not much compared to the price attending World Cup competitions.
BUT, there are also beginners who might be interested in trying electric power models, maybe flying only local competitions.
For them, 80 euros (per plane) may be a considerable price comparing the the price of the other model power train components.
Also, availability of the limiters is an issue, here in Finland there are no for sale, so you need to know your contacts and
have information to know what to shop for! I feel that the secondary way of static power measurement is an
important way to allow easy access to the class.

Aram Schlosberg F1Q was designed specifically to be an 'open' event in which one could fly a wide range of models.
An energy limiter is not a requirement since a model's energy can be tested on the ground with a Wattmeter and a
stop watch allowing cheap and simple models. Another feature is thse E36 models that are popular in the
States can participate but are generally less efficient than Q models. The even combines features of B and C
which offer interesting design opportunities. Lifting the motor run ceiling from 20 to 40 seconds allows even
a larger class of models (my proposal was for a minute ceiling).
But dropping the motor run ceiling to 10 seconds or requiring energy limiters will create a
narrowly defined event and all the competitive models would be factory built. And participation would plummet.
My point is that The Q rules are fine as they are and that the 'what if' scenarios and alternative rules only hinder it's development.

Don DeLoach If the F1Q rules (perhaps 10 flyers in the USA) are "fine" how would you describe the E-36 rules
(literally hundreds of USA flyers...I've sold 325 kits)?

Don DeLoach Here's a ruleset for F1Q. 1. 3 cells lipo max 2. Minimum weight 350 grams 3. 10 second motor run.

Simple. Would be popular.

Aram Schlosberg There are probably 40-50 E36 fliers in the States and it is definitely one of our most popular events.
Each year about ten people approach me with grand ideas of how to 'fix' Q. But none have built or flown a Q model.
Maybe the best to build and fly one instead of trying to first 'fix' the event.


Tapio Linkosalo Don, in my opinion your simple ruleset for F1Q would not work. There needs to be some kind of
limitation for the energy (we had this discussion 10 years ago when F1Q rules were first established);
in F1Q the limitation is by the energy limiter or max power measured at midpoint of the power run;
in E-36 the lack of autosurfaces and therefore (almost) mandatory spiral clim works as a limiter.
In F1Q, before the limiters, models were already climbing to 150 meters in less than 7 seconds, so with
your rules we would see autosurface models climbing to 200+ meters in 10 seconds, and doing 10+ minutes in dead air.

The lack of autosurfaces is one interesting way to limit the maximum power, but in any case,
some kind of limitation is needed.

Don DeLoach Okay Tapio. I agree a ten minute class is not desirable. How about 3 cells, 400 grams and 6 seconds?
I just don't see the need for the complexity of an EL. Complexity is what repels participation.

Don DeLoach Aram: In order to understand how hot a stove is I need to touch the stove and get burned?
No, actually, I'm smart enough not to do that.

Tapio Linkosalo Don, I think (and referring to the early discussion of F1Q rules) there primary need is to somehow limit the maximum power of the motor. In IC motor classes this is done by limiting the motor volume, but for electric it is not straightforward to do the same. For one thing, limiting battery size does not work - battery technology is developing all the time. Maximum number of cells does half the job, by limiting the maximum voltage, but in addition the current would also need to be limited. Energy limiter is one option, but (as we have seen) maybe not the ideal one. Another option could be serial shunt (resistor) or fuse between the motor and speed controller, but measuring/calibrating these is not straightforward either. Third option would be limiting the motor size (can length and diameter), but this would lead to competing with motor properties - magnet quality and all motor dimension (like clearance between can and stator).

All in all, no-one has yet found the "philosophers stone" of easily limiting the power of electric power trains....
and this prevents F1Q from bursting to flower.

Don DeLoach Limiting cell count in E-36 has worked great. Therefore it won't work in F1Q?!

Don DeLoach Forget about finding the perfect way to limit doesn't exist! F1Q will never succeed
unless and until simple rules win the day. In the meantime I and hundreds of other E flyers will continue to enjoy E-36.

Don DeLoach I have sold Super Pearl E-36 kits to flyers in 14 countries now, in barely three years.
In almost every case flyers have remarked of their frustration with F1Q.

Tapio Linkosalo Don: "Limiting cell count in E-36 has worked great. Therefore it won't work in F1Q?!"

It all boils down to energy. The amount of energy available times efficiency equals the altitude.
For electric motors, energy equals power multiplied by motor run (time). Power equals voltage times current.

Therefore, limiting the number of cells in the battery is only half of limiting power.
You can overcome limits of cell count by increasing the current running though the system.
It may reduce the efficiency of the power train, but in any case higher current still means higher power, and
hence higher potential altitude.

To limit the model performance you also need to limit the current.
A shunt or a fuse would limit these, but they are difficult to measure
accurately, and therefore impractical. A energy limiter is more adjustable and transparent way,
but is has its shortcomings. BTW, the alternative way suggested for F1Q, measuring the power halfway
through the (static) motor run is also one means of measuring the current of the power train.

As I wrote before, E-36 makes another, quite interesting means of limiting maximum power by
aerodynamic means; for a model that must climb, glide and transition from former to latter
without auto surfaces the trims show the limit for the maximum power that the model can handle.
At least for the time being. It is possible that clever trimmers can trim their models to quite high
performance even with this approach. Time will tell!

Michael Woodhouse Don. You are right on the money

Aram Schlosberg Does anyone know why the FAI version of E36 proposed made year called F1S was withdrawn?
If the event is so popular - as claimed by an E36 kit producer, why not accept it as a mini-FAI event?

Don DeLoach You don't believe that I've sold hundreds of kits Aram? Hundreds.

Don DeLoach Ian Kaynes withdrew his F1S proposal unilaterally at the plenary meeting in April.
I was initially disappointed, but now I think it a good thing that CIAM doesn't mess with E-36.
They would surely screw it up.

Michael Woodhouse That is why it was withdrawn. CIAM screwed up F1Q, they sure as hell would do the same to E36

Tapio Linkosalo To me, the suggested rule set for F1S seemed OK, following the lines of E-36 except for
being flown in rounds in the FAI ways. Therefore I was disappointed to see the withdrawal,
I would have liked to see uniform rules for the class; now I fear that it will see the same faith as P-30,
with different adaptations for each different country...

Aram Schlosberg Matti - F1Q includes BOTH 5-second and 25-second models and fliers might bring
both and fly each in the most suitable conditions. Q was never intended to replace C but could, in my opinion,
be flown in parallel at a world championship (hopefully soon).

Aram Schlosberg In addition, I think it would be a good idea to revive the F1S event again. E36s are simple and fun to fly!

Don DeLoach US flyers don't like rounds, by a wide margin. Forcing E-36 to fly five rounds would be very unpopular.

Tapio Linkosalo I do not think flying in rounds or not in rounds is the major issue here
(just recall someone pointing out that F1S was E-36 flown in rounds); just have gotten the impression that in the US
you fly FAI classes in rounds and AMA classes without.

Don DeLoach What I'm saying is many flyers in the US avoid events that are flown in rounds, solely
because they don't like rounds flying. If CIAM hijacked F1S and forced them to fly in rounds, US flyers
would likely rebel and simply retain the original E-36 with three flights.

Tapio Linkosalo What I'm trying to say is that it is all up to you (or CD) to decide the format you fly!
Here in Finland we typically fly our F1H contest so that in the first 2 hours you should do two flights,
and in the second two hours (or earlier, if you have finished already the first two) the remaining three.
We _could_ go to " 5 rounds within 4 hours" format, but for me (as CD) this pattern feels fairer, as it gives more equal
conditions, less chances trying to pick the best fraction of the day for flying all rounds...
But anyway my point is, F1H rules do not dictate the contest to be flown in 1 hour rounds!
(FAI contest rules do, but those only apply to Championships and World Cups...)

Aram Schlosberg I just got a terse response from Ian saying 'The F1S proposal was withdrawn at the CIAM
Plenary meeting, so the class will not exist'. I'm completely in the dark on this one. E36 is a nice mini event
and why bar the non-USA fliers from enjoying it in a FAI format while we in the States fly the AMA format?
Another possibility is that we could fly F1S in rounds on one weekend day and E36 in the AMA format on the other day.
Just double the fun!

Don DeLoach I like that idea Aram.

Aram Schlosberg Maybe we could revive the F1S proposal with rounds or something along what
Tapio does (fly two flight in the first two hours and three in the next three hours) followed by incrementing the max
time in flyoffs with the understanding that in the States E36 (National Cup) and F1S (American Cup) would
be flown on different days of a weekend.

Aram Schlosberg Back to F1Q and a future World Championship. The criteria to having a World Championship is having the
event be flown widely and have contests attended by fliers from other countries or even continents.
So Q fliers should lobby to have Q included in World Cup events held in their countries.
In fact, the dead line for submitting World Cup applications to CIAM is November 15th 2014, just around the corner.

Teppo Sarpila First I like to see how season 2015 will be. We have made very good changes for 2015 and we have to look
how they operates.

Teppo Sarpila There are some changes in sight, but they can wait. What are the differences in F1Q and E36/F1S are tree points.
Maybe this are the main things?:

Teppo Sarpila 1. The size of model in E36 is fixed, span 36' min weight 120g. In F1Q not.
2. Fixed surfaces in E36 in F1Q not,
3. Use of energy F1Q yes, E36 not. Maybe this are the points why we have a feel that E36 is more popular.
Reality is that F1Q is much more compligated than E36.

Teppo Sarpila I never like to hear that F1Q would be supstitute of F1B or F1C.
It is the class of its own. I have sarted to fly F1Q from begining ( seasion 2007) .
The models then I can fly also today. I dont have to make new models due to rules.
The reason to make new models is to get them better than before.
There are many ways to go and that is why I like F1Q.

Matti Lihtamo When competition intensifies, I do not believe the diversity of a permanent in class F1Q.
The rules will be to guide class in such a way that successful model will be as similar to each other.

Aram Schlosberg Time will tell.


Missing SEN


How did I miss SEN 1918 – 1921? Or did I? The last one I received was SEN 1922. Just curious.

Good job at the finals Rogers I heard a lot of good comments about. It certainly wasn’t easy….

Marty Schroedter


It appears that there may have been some issues with our service provider’s servers as some others have r[ported some strange anomlaies.

All appears to be working now.

You can find the back numbers on the and (NFFS) web sites. NFFS seem to be a little behind too as they might have missed some issues. I did update ours.

The finals was not as hard for me was it was for some of those flying. While the weather was a little challenging at a couple of times, I think the thermal conditions were even more challenging when the weather was nice.


Roger Morrell