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Thursday, November 1, 2018

What futur for F3F ?

Hello all,

No ... I will not talk about the drone law that is coming, this is another topic :) !

Following the F3F world championship in Rügen, I think it is the perfect time to make a step back, to learn the lessons and think about the futur of F3F:

Personnaly, the 3 main lessons learned in Rügen are:

  1. A round with 63 pilots can take between 2 hours and 3 hours depending of conditions. During this time window, flying conditions can change a lot. For exemple in the morning when the air is still wet and the drying when the wind is raising, leading to 10s time difference, if not more.
  2. Starting order draw must be carefully done, which was not especially the case in Rügen
  3. When groups scoring happens (round interruption or end of the day), scoring can become very unfair because of the third man effect.

F3F is a nice category because rules are simple, and because we are flying in very different and nice to amazing places. All this make me think that participation will increase in the futur and competition will be even more larger, especially the world championship.

We have 2 years before the next WC. Why not brainstrom in order to make the rules to evolve in order to organise fair competition with a large number of pilots, an ensure everybody enjoy and not consider that sometimes F3F is just like casino, depending too much of the stating order ... or, at the opposite, to conclude that the current rules are perfect as they are today, who knows !

On top of that, I think there are few point in the rules that should be clarified to avoid interpretation like penalties in case the round is cancelled, round interuption reset in case of flight attempt but not valid, etc ...

Personnaly, I don't want to see people who don't fly F3F to try to impose us rules that we don't share, as it has been in a recent time.

As a starting point for this brainstorming, why not first reconsider is the scoring method. France proposed a rule change in 2010. Timing with CIAM calendar was wrong so I think the proposal didn't reach the Plenary meeting. Also, at that time, community was reluctant to this sort of change. During the technical meeting at Donovaly in 2014, I re-explained this scoring method and some people thought further and I could feel some interrest in some nation. Maybe today time has past and with experience of large competition, people are now ready in their mind to look at this rule change with opened eyes.

So here is the rule proposed initially:


F3F rule change proposal

The objective of the present rule change proposal is to modify the pilot round result calculation to use the round average time instead of the best time. This make the round ranking fairer in case of group scoring. For details description, please refer to the presentation included in this document.

The result of the flight is stated as the time in seconds as hundredths of seconds obtained by each competitor. For the purpose of calculating the result of the round the competitor’s result is converted this way:

1000 * Pw/P

where Pw is the average result of all competitors and P is the competitor’s result.

Reasons behind are:

  • In case of group scoring, the final ranking is made much fairer 
  • By reducing the “third man effect” final ranking is made more consistent with real man on man ranking 


FAI current scoring formula

F3F scoring is based on a comparison between the time of the run and  the best time of the round:
FAI = 1000 * Best Time / Pilot Time (Best time is used as the reference)

The amount of points you get after your run depends on 3 parameters:

  1. Your skills (the parameter we want to measure).
  2. The flight conditions you get during your run (that induces the famous "lottery effect") 
  3. The flight conditions during the best run ( that induces what I call "the third man effect" and adds some additional "lottery effect" to your own run.

"Third Man Effect"

The number of points you get depends on your run but it also depends on what happened during the best flight:

- A "top pilot" got the "1000" with average conditions
- A top pilot got the "1000" with "the thermal of the day"
- An "average pilot" got the "1000" with a "standard" thermal

Between these 2 pilots: Who is the winner ?

You think this is Pilot 2 ?

The real answer is : we can't know !
The final ranking depends on the "third man" : the guy who wins the rounds

Because of "third man effect" today FAI scoring method may make the final ranking not coherent with the real man-on-man ranking. The "third man effect" enhances the lottery effect.

To reduce the "third man effect" it is proposed to replace the best time of the round by the average time of the round

New = 1000*Av.Time / Pilot Time

Using the average time instead of the best time makes the reference time much less sensitive to flying conditions. Lottery effect due to third man effect is quite cancelled. But lottery effect related to your own flight remains the same. It has been verified that both methods give quite the same ranking when flying conditions are stable. Differences may occur when flight conditions are very variable . They always make final ranking consistent with man on man ranking.

Group Scoring

It is well known that group scoring can be dramaticaly unfair. This is the case when a pilot get a huge thermal scaling down the scores of all other pilots in his group (but having no effect on the other group).

Exemple: first 2010 competition in France (only 3 rounds with group scoring in the third round)

Pilot “A” makes a 35s => only 2 pilots in his group are around 820pts and all the others have (much) less than 800. On the second day the air is much lighter but much more stable => in the second group more than half pilots have (much) more than 900pts. At the end of the comp all pilots in the top ten (except Pilot “A”) were from group 2.

In case of group scoring the new scoring method is much fairer because in both groups the "average pilot" will get the same number of points (around 1000) wathever the best time is. if some care has been taken to make both groups of egal value this result is very fair.


It is proposed to use the "average time" instead of the "best time"in the F3F scoring formula. This modification has two advantages :

  1.    global ranking is made consistent with man on man ranking
  2.    group scoring becomes perfectly fair

Don't be wrong ! This new method scoring will not affect the result of the pilot getting the thermal or flying very well, "killing" the group. The objective of this scoring method against the average time is to not impact the pilots compared to the other group where all pilots are flying around the same time.

Now that group scoring doesn't impact negatively the pilot scoring, why not consider group scoring to be used in every round for competition with more than xx pilots ?

We could imagine groups of pilots between 10 and 15 (or more) depending of the total number of pilot.

But to make the competition as fair as possible the composition of the group must be done carefully to avoid pilots to "meet" the same pilots several time. Such algorythm exists already in other categories like F3K or F3/5J, so could easily be adapted to F3F.

This approach would allow fair competition with large number of pilots, maximizing the number of round flown during the day as we can fly a group before the night, and resume the next day.

Of course all this must be studied carefully, with simulation, etc ...

But I really think that we should spend some time to evaluate the benefit of theses changes, and not stay on the current rules and complain.

So how to progress on all this topic ?

I was thinking that we could create a international working group with one representative of each (active in F3F) country, who could play the role of relay with the different national communities. This representative could be the official category representative of the country, or a delegate, an active and experienced F3F pilot. This working group could brainstorm, work on ideas, simulations and finally eventually propose some rule changes with a wide support, following the CIAM / FAI calendar. I know there is a wish of the FAI/CIAM to have such working group.

Ready to participate/contribute ? Stay tuned !

Thursday, October 25, 2018

Review: Judge F3B from Duffek model

Judge F3B from Duffek model

by Sylvain Coulomb

A new glider called Judge appears in May 2018. Look and design is close to most recent available toys (Pike 2, Pitbull 2). Little information available on design made by Jan Stonavsky and Duffek model:
  • Wingspan - 2980mm
  • Length - 1468mm
  • Wing area - 56,82 dm2
  • V-tail area (proj.) - 5,65 dm2
  • FAI area - 62,47 dm2
  • Weight - 1850 - 4685g
  • Wing loading - 30-75/dm2

After a first contact, I decided to make F3B version testing for next World Championship as an economic alternative to other very expensive gliders. I am helped by Julien Gourdet, our first French representative pilot for Jesenik 2019.
Data are available at http://www.duffek-model.cz/cz/index.php/kontakt-2
Duffek Model is close to Vaclav (Stinger, Sonic…) and they seems to share reasonable and fair commercial vision.
Filip Kalensky has done a great job to present F3F version, installation and setup at https://www.rcgroups.com/forums/showthread.php?3088222-Judge-f3f-f3b
Website says: This model is fabricated in diverse strength variants of the best composite materials. The model is an excellent competition machine for all types of weather conditions. Perfectly holds the selected flying line in a turbulent environment and, thanks to aerodynamic purity, has a high penetration rate in the wind. At high surface loads it retains good dexterity.
Our test is there to present F3B potential of the Judge and verify designer assertions, F3F information coming by Filip.
So I ordered the F3B Light version presented in this article. (And also a standard one not presented here). Both delivered with hook not supplied for F3F.

Parts weight :

  • Left wing : 600 g
  • Right wing : 602 g
  • Fuse : 206 g (with command)
  • conus :   34 g
  • Elevator L :   34 g
  • Elevator R:            32 g
  • Joiner : 125 g 
  • Accessories :   25 g
  • Supplied nose brass : 110 g

After installation, wiring and CG adjustment (102.8), empty flying weight is 2040g witch is very correct for F3B even if some models could be lighter. 
Model examination:
No particular remarks on manufacturing. Quality is equivalent to most high quality gliders (Baudis model, Samba…).
Some improvements have to be made and should be fixed shortly by Duffek models:
  • Servo caches are too small so I replaced them by transparent PVC  (I suppose an error easy to fix)
  • LDS system screw still delivered with MKS size and should be for KSTX10
  • Fuselage commands good for F3F replaced by me with lighter one to save back weight 
Actually the model is delivered without ballasts and wires, with wings and elevator bags. 
Prices are to be checked with manufacturer but are around 1500€ for the 3 versions.
I decided to mount available MKS servos but Judge is done for KSTX10. Both brands will fit in. LDS installation is easy but need attention before gluing servo supports.
Filip installation is on line so; I don’t develop except light changes.

I soldered LI-ION batteries with long wires to install them one by one with no change in existing holes to keep fuselage as is. No space problem to add servos, Zepsus, batteries, cables…
I hesitate to add ballast tube and forget it for this one. In distance, it could be interesting to quickly modify weight with no time to dismount wings.
So, in less than 8 hours, it was ready to fly … waiting for good weather!
Personal ballasts set:
I took an option with 4*40 g in the front 4*110g in the back in order to move CG backward if it fit after tests. Otherwise, I will reduce weight of back ones.  Front are 10*10, back are 20*12, Joiners are 8*8 … All this is adjustable depending of your habits and set up. For sure, it is possible to add more than 1800g ballast even if not so frequent for F3B.

Preliminary flight tests:
As a glider is long to set up, preliminary feeling will be confirmed in some flying sessions.
Two sessions were held on slope with poor conditions (no front wind) to verify CG and first command rates. Then we could test on field which is this version target.

Saturday October 20/ wind around 17km/h/sunny

Empty CG 102.9 2070g Distance light 103.2 /2500g Hook at 103 from leading edge.
First launch: not enough elevators (safety) ... so bad launch but Judge seems rigid and good zoom --> already average high compared to others
Second: nearly perfect, easy to drive and high altitude ... quite impressive because we have certainly better set up to test!
All day long: adjustments (differential flaps ...). Very good feeling and apparent stiffness
After adjustments: performance is there, quite easy to adjust everything to place the model where and how (attitude) you want. 
Butterfly is easy to manage with very good stability. Smooth landing with adjustable speed/distance to stop in target. 

Sunday October 21: Contest/wind around 13/15 km/h Conditions less good than Saturday on thermal standpoint.

We decided to have Julien flying the contest with Judge (and my TX) after problem on FS3 servo. He had launching difficulties all the day due to switches position on my TX ... so altitude and results could have been easily better with his own material.

Even though, he won all his durations, distances (3 To 5 laps more than others); and makes good speed (better and better time to adjust) including a 1000 in one round. 

Confirmation of Duffek model website:
  • Strongest parameter seems "facility" quite rare with an unknown new machine.
  • Second is clearly performance in distance and turning facility and precision (you really can choose your turn style depending on speed/conditions/ballast). Distance is really a pleasure and good cadence is easy to maintain. Julien liked it!  Setup to improve and maybe 102.8 better than 103.2 (little bit touchy - to be confirmed)
  • Speed to be confirmed but promising (Julien didn't ballast too much for first tests with a friend’s materiel)
Without the first 0 with FS3 servo trouble on duration, Julien would have been 2° at 5 point from the first. For a first test we couldn’t expect more!
Global balance is really positive.

Some points to check for potential improvement:
  •  Not really checked: Stiffness. Model seems quite stiff enough but has to be confirmed with more ballast. No bad feeling at this point because we made some "hard" zoom during set up and nothing bend ... To be confirmed in hard conditions.
  • Light F3B version is really much optimized and skin is really thin (60g carbon). This could be a concern close to the joiner because you need to be careful during wing mount to prevent fingers marks. High level pilots are used to and prefer to save weight. Normal pilots would probably prefer standard version for better model life. Weight increase is not really a problem with model duration capacities. Discussions are in progress with Duffek in order to add one more layer on the wings first 20 cm to definitively prevent the fingers marks risks.


Still confirmation to wait after more flight time but really a pleasant, easy (and performing) model compared to current models we have (FS3, Pike 2, Device) in the team. For sure, it will be long to confirm because high level performance is reached by best pilots after month of setup and flight hours but for normal good pilots like me, Judge is already a model better than my own flying skills limits.

Have fun and good flight, 


Wednesday, October 24, 2018

Our hobby, our passion is in danger !

Dear all,

Our hobby, our passion is in danger !

Please read carefully the text below translated from Finesse+ webpage.

EASA issued in 2017 a "NPA" (Notice of Proposed Amendment). Following the many comments (more than 3000!) From stakeholders, including those issued by Finesse Plus, the EASA published early 2018 a document (Opinion No. 01-2018) less constraining for model aircraft than the NPA initial. This summer, the European Parliament also passed an amendment to the Basic Regulations for Aeronautics to include unmanned aircraft.

Now the European Commission is asking EU citizens for their opinion on the draft regulation before its finalization and final adoption. Make no mistake, unmanned aircraft (Unmanned Aircraft, abbreviated to UA) include both drones and model aircraft. We are therefore directly concerned ...

To read it, go to https://ec.europa.eu/info/law/better-regulation/initiatives/ares-2018-1460265_en and download the two documents relating to the Implementing Regulation which are open to comments until November 5th:

      – Implementing Regulation – Ares(2018)5119803  (Fichier PDF: PART-2018-221538V4)

       – Annex – Ares(2018)5119/1 (Fichier PDF: PART-2018-221538V4 (1))

Finesse+ experts analyzed these documents in detail and detected two real risks for the sustainability of our activity outside the club grounds (classified in category OPEN A3 according to the EU regulations), in particular for mountain flying, of which One is a clear step backwards from the EASA Opinion:

1 / The height (not the altitude) of flight of the model is limited to 120 m above ground level (Article 4 (1) (e) page 5 & UAS.OPEN.10 (2) Annex, page 1). Problem in VDP, as soon as you take off, you are above the hole ... and the 120m / ground can be reached very quickly if the hole is deep or as soon as you take altitude ... If the altitude difference is 120 m or more to fly in front of you while remaining at the level of the slope becomes totally impossible.

Note: Beyond slope soaring, Finesse Plus had proposed to EASA in early 2018 to increase this height to 240m / ground if an observer was present to inform the pilot of the possible arrival of manned aircraft in the area. DMFV (Germany) and FSAM (Switzerland) also made similar proposals. Unfortunately, this has not been retained by the Commission in the text we are asked to comment on.

2 / The flight of slope or plain off land declared will be made very difficult because the draft regulation indicates (UAS.OPEN.040 (2) Annex, page 3): "be conducted in an area where the remote pilot reasonably expects that will be present in the range where the UA will be flown during the entire time of the UAS operation ".

In summary: no flights possible if walkers are likely to be present in the area of ​​evolution. However, to date, it is the pilot who analyzes the risks vis-à-vis the walkers or other observers and who ensures the security. The EASA Opinion was more pragmatic because it mentioned "... in an area where the pilot will not be able to go anywhere". That is to say, to make sure that there will not be on the site of the uninvolved people endangered, which is what we already apply for 50 years ....

a/ Article 4(1)(e) & UAS.OPEN.10 (2): Requiring that in OPEN Category the UA shall remain at a maximum distance of 120 meters from the surface of the earth even when starting from a natural elevation over terrain is not relevant at all for sailplane models starting from top of a hill or a cliff to perform slope soaring. This would compel the pilot to fly the model below his/her position when the starting point is 120 m or more above the surrounding terrain, as it is the case today for many slope soaring sites in mountainous areas.

 Moreover, the remote pilot has no mean to precisely assess his/her model height above a terrain which is below the elevation of the starting point.

 To accommodate slope soaring operations with sailplane models, the height limit should extend horizontally from 120 m above the remote pilot position rather than following the terrain contour.

 Consequently, UAS.OPEN.10 (2) should be deleted and Article 4(1)(e) amended as follows: « the maximum height shall be no more than 120 meters from the take-off point, except when overflying an obstacle, as specified in Part A of the Annex »

b/ UAS.OPEN.40: Requiring that OPEN A3 operations shall be conducted in an area where the remote pilot reasonably expects that no uninvolved person will be present is unworkable, in particular for flights in mountainous areas where hikers may temporarily pass through the area of operation at any time. This was recognised by EASA in Opinion 01-2018 where the word « present » was replaced by « endangered », taking in consideration this ensures better consistency with the related Acceptable Mean of Compliance (AMC1 UAS.OPEN.040(1)) requiring that « when a person incidentally enters the visual range of the remote pilot, the remote pilot should avoid overflying the person, and discontinue the operation when the safety of the UAS operation is not ensured », as model aircraft flyers are already usually doing today.

Consequently, UAS.OPEN.40 should be amended in line with EASA Opinion 01-2018 as follows: « «…in an area where the remote pilot reasonably expects that no uninvolved person will be endangered within the range where the UA will be flown »
How you can help ?  By giving your feedback to the European Commission.

Step 1: Create an ECAS account (EU login):


Click on "register" or "give feedback" and follow the usual procedure of creating an account with password and validation by email. This ECAS account (EU login) can be used to participate in any European Commission consultation on any subject.

Step 2: Once logged, give your feedback

Go back to the home page and in the section where you downloaded the documents (Draft Act - Draft Implementing Regulation), click on the yellow square "Give feedback".  Here is the type of support message we suggest you enter:

"As a citizen of the EU having more than xx years of experience in flying glider models safely, I fully support the comments posted by the association Finesse Plus, namely:

            – The need to amend Article 4(1)(e) in order to extend the height limit horizontally 120 m above the remote pilot  instead of following the terrain contour

            – The need to amend UAS.OPEN.40 in order to allow the possible presence of uninvolved persons in the area of operation provided they are not endangered."

Of course, you are free to make a comment using your own words, the main thing being to ensure a good level of consistency between all the comments made by our community. Please note that your comments will be immediately posted on the Commission's public website and thus visible to all. Other commentators can also react online to your own comments.

Due to our aeronautical culture, we have demonstrated a high level of safety for more than 50 years. Even if EASA and the European Commission agree, as much remind them once again ..

Time is running ! Don't let burocrats and politicians to kill our hobby !

Tuesday, May 1, 2018

Stribog+ assembly

I managed to assemble the Stribog+ in a bit more than a week.

I started with the fuselage rear part. I cutted the lips receiving the rear cap to keep them 5mm large. Then I installed the brass threated adaptor (MpJet) and the metal clevises. The adaptor is pinched and glued, after removing the teflon on 10mm on the snake rod.

Finally, I could put the tails in place and glue the elevator control horns at the optimum position to obtain the needed throws, and not having the clevises touching each other.

The tails centering pins are glued with a drop of cyano, otherwise, they are staying on the fuselage when removing the tails.

The reap cap need also some cutting allow the control horns to move. I did it progressively, using a mini drill.

Let's continue with the wiring and connectors. They were provided with my Stribog+, but having my habits, I made my own wire harness. In the fuselage, I glued 2 x 1mm wood plate with a 2mm recess on each side in order to create a stop point for the plug. Then the plugs are glued in place with rapid epoxy.

The routing of the wire to the nose is very easy in absence of a ballast tube in the fuselage.

The Servo tray is in place and prepared for the standard 12mm servo size. Absolutely no rework here, the servo enters without forcing on wires. I used the HV6125e screwed with 4 MPjet screws (very good quality). Once elevator servos in place, I finished the eletor snakes with brass threated adaptor and plastic clevises from MPjet (again ;)! ). To secure the elevator sleeves, I used some epoxy paste from UHU. You just mix the paste together, and apply, and let cure.

As receiver battery I used the usual LiIon 18650 2.9Ah with a servo connector as balancer plug, if needed. More info can be found here:


Wing servos installation. This time, LDS was provided apart, so I had to installed them. The installation is pretty straight forward. I started by connecting the epoxy arms in the control surfaces, using the tool provided (a long brass rod with a threated pipe at the end). the mounting was so tight that I needed to grid a bit to free the movement. Once completed, I just glued the servo frames in place with the servo head and servo in place to adjust the position with the control surface at the neutral position.

As you can see on the pictures, I mounted 4 HV6130 from MKS. I usually use the 6625 and 6625 mini, but I have been contacted by MKS USA to test the new gear train. In fact I received 2 upgraded 6130 and 2 new 6130 already with the new gear train. I have mounted them radomly as I couldn't distinguish them from  eachother.

The mounting of the LDS with the 6130 is very very tight, and there is no slop at all. I will monitor closely how the servo behaves with time, and under heavy sollicitation.

The servo 6 pins connectors are glued in place with rapid epoxy on the root of the wings. The assembly finishes with the cutting, ajustement and taping of the servo covers in place.

I needed about 200grs of balance lead. It is located in the nose (100grs) and on top of the battery. The empty flying weight is 2380grs with a CoG at 106mm, exactly the same as the Stribog.

For the throws, I just reused the model memory on my radio, and just tune the neutral position, but for the rest, it is identical.

Before to run to the slope, I created the spreasheet for the ballast that give the best ballast slugs combination and the variation of CoG when increasing the ballast with correction when needed (Many thanks to Alvaro Silgado for sharing this very useful excel macro).

Friday, April 13, 2018

RTGmodel.sk also released a nice F3K competition glider called Alatyr (the name is again coming from the middle age mythology, Alatyr means the father of all the stones) that is available since January. The plane is designed by J. Pejchar who is already behind several F3K design. The Alatyr is at the standard 1.5m wingspan, 1.04m length and feature a Pe16 airfoils for the wing and the HT22 and HT23 modified section for the tail. Quality of the kit, which arrives with nice wing bags, tail and rudder covers, is just oustanding, in term of fit and finish which is not surprising knowing RTGmodel quality. The wing uses a foam core. Component weights are the following:
  • Wing: 120 gr
  • Tail: 6gr
  • Rudder 5gr
  • Fuselage 31gr
The kit comes will all the necessary accessories, including a servo tray and servo frames for the alerons servos. Below is the link to the photo album

Wednesday, April 11, 2018


The flagship from RTGmodel (http://www.rtgmodel.sk/) has just received some evolutions and is now renamed Stribog+.

The main changes are the slim fuselage that is no more hosting ballast, and the apparition of a wing compartiment in the wings. Planform and airfoils of the wings remain the same and the tails is not modified.

Ballast for the joiner (628gr) and for the wings (1627gr) is provided and now allows to reach 2.2 kg compared to the 900gr of the Standard Stribog.

Moulding Quality is still second to none and some details have been added, like the servo tray front lips that are going up to remove the potential fuselage failure under the canopy. Component weight are the following:

- Left wing: 639gr
- Right wing:623gr
- Left tail including joiner: 42gr
- Right tail including joiner: 42gr
- Fuselage: 347gr
- Wing Joiner: 95gr

As a reminder, the Stribog is a very competitive and capable F3F plane. I have flown my unofficial personnal best in 26.21s with it.

Merry Christmas !