RE: F3A Results - SPOILER
 

Hi Jason,
Yes it says K 74 or more.
I was wondering if there is 3 with K6 or more picked can these be regarded as being 3 of the 4 K5's.
Mute point really if the total is a required 74 min.
You are right about the EC's not being 74.
A question for M Ramell I suppose.
It's not a great rule really as I think some of the international judges will struggle with the complexity - another hot topic !!

Brian

RE: F3A Results - SPOILER
 

In reality, you are never running an IC or Electric at full throttle for the entire flight. I would average say 30-40A for the whole P13 flight with peaks around 80A.

We are now seeing airframes becoming lighter and lighter as manufacturers realise just how much less strength is required with e-power. Power to weight ratio then comes into play. Then we have battery technology getting better and better BUT I'm concerned that high C ratings are becoming more common place than 20-25C light packs. Hope this trend reverses. With the airframes weighing less we can probably afford to increase the battery capacity and still be under the 5000 gram limit.

Just my $0.02's worth...

Cheers,
Jason.

RE: F3A Results - SPOILER
 

Those C ratings seem to be a bit Iffy- Having bought the $$$$$packs and some very inexpensive packs - guess which ones delivered the best performance without getting hot n puffy?
From what I have tried /seen etc., the 30C packs which sell for around 50-55 bucks apiece (5000ma 5 cell) are probably the best bang for the buck
If you can do the model at an all up of 10-10.25 lbs - you gain a BIG power to weight advantage - and you don't have to work the cells as hard.
In the "future" stuf -I expect to see more models in this weight class.

RE: F3A Results - SPOILER
 

FWIW, FAI bulletin EI for the 2013 Worlds in SA lists the field elevation at 4,872 feet. The average daily maximum temp is listed as 22 C (72 F). At standard pressure of 29.92" the density altitude at 22 C (dry) would be 6,777 feet. At 66% RH, it goes up to 7,034 by another calculator (relative air density of 81%). Average sustained wind speeds are listed as 2-4 m/s (4-9 mph), peaking at 2pm.<div></div><div>http://fai-f3aworld.blogspot.ca/p/28th-world-championship-south-africa.html?m=1</div>

RE: F3A Results - SPOILER
 

The US F3J Soaring Team is in SA right how (Johannesburg) and it has been bitter cold with nasty winds!! Keep in mind that summer for us in winter for them. They even had SNOW!!

BTW - the USA F3J Team just won the Team Gold today and we got 4 seniors (the whole Senior Team and 5-time Soaring Champion, Daryl Perkins) and 1 junior into the Finals.

RE: F3A Results - SPOILER
 

Brian,

I am not sure what you have been reading in all this or maybe I just do not understand what you are saying but I in know way implied I would of beaten anyone if I would of had a YS at that contest. Once again I will try to explain myself as best I can so there is no confusion. All I am thinking IN THE FUTURE I will have two setups thats all. I have nothing but praise for the guys the came in 1st 2nd and 3rd. I practiced for a couple weeks and went for fun. Sure it was nice to be competitive but it was know surprise to me to come in 4th. I am now thinking about the future and if called upon how to be the best prepared for me to do well in SA. It is going to be at a time of the year when it is very possible to have pour conditions as well so why not be prepared. If in your mind that makes me a poor workman then so be it.

C

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WHAT?? A poor workman blames his tools?

C'mon there guy..... not at this level.... I didn't get THAT from what the man said.

Jim Oh has it right. It's matter of energy not power. Each gram of wet stuff has a fixed amount of it. Each gram of a depleting battery has a variable amount of it. On the other hand, I think many of us have been involved in contests with howling wind and have horror stories to tell. In reality tho, these are very few and far in between so needing that much energy is infrequent....

And BTW- only 6 ozs of gasoline are required to fly a schedule. That's about 4 1/2 ounces of weight. So much for weighing IC, gas power anyway, fueled and RTF

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Hi Chip / Matt,
Yes I agree that was loaded question.
I just think Chips last post is absolutely fair and apt,, , where as post 17 puts it differently.
Someone at Chips level can sometimes make or break an idea with just one statement.

We all struggle to properly contextualise our comments here, I know I do anyway.
I put up a post saying 'this goose is cooked' with no context in the post.
I wrote as I thought not as I intended others to read.
Sometimes when this happens it is very difficult to get back to the start as people pile in and the thing takes on a life of it's own.
Like it or not top people have a greater responsibility in this regard due to the influence they exert.

Brian

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Thanks all for the courage and candor in telling your Nats stories and related posts over the last few days. I learned a lot reading them. While the extreme conditions are statistically rare, this year's finals stories gave me insight on the challenges of competition at the top, especially when the winds are howling. Reminds me of a quote I read on one of the threads, don't know who said to first: Most practice till they get it right; experts practice till they can't get it wrong. At my age and experience level, more about inspiration than action LOL as there is only so much free time for practicing pattern, and yet it's a whole different approach to flying models. For example, making weight or making it lighter still; flying in poor conditions when I'd rather be somewhere else, and so on. Thanks again guys, it's been real learning from you here, priceless really. Please keep inspiring us.

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I'm jumping in late.......took a week off after the NATs, and then spent a week cleaning the shop and lining up experiments and testing for next year....influenced no doubt by the 74K unknowns, which is even more of an influence in strong winds.

I'm not smart enough to cut/paste multiple quotes to respond to......but.....couple points I would add -

I've flown identical planes side by side on the same day multiple times with the only difference being single prop vs Brenners Contra system. On a radar gun, the top speeds were equal, and when flown through the pattern, the flight times were always within 5 seconds, with the greater influence on time being the pilot, not the powerplant. Without a doubt, 100%, spiral airflow, torque, PFactor, and gyroscopics are real (just like the science says) and ARE AFFECTING our pattern models. I am not suggesting our pattern models can not be designed, trimmed, setup, etc, to greatly minimize the effects, BUT, the effects are real, and do cause trim problems if they are not addressed (and they can not truly be cancelled out), and they are all but eliminated with the Contra system. I say all but eliminated as the relative RPM / torque of each prop on the Contra is not always balanced in transient conditions. Another point on this that I will add.....maneuvers that require rolling left and right, or snapping left and right, or require both positive / negative corners are often among the most challenging....outside of the challenges to the airframes, ergonomics and habits are also factors. The ergonomic factor is simply that our hands are not symmetrical when pushing left aileron vs pulling left aileron (for the Mode 2 flyers), and the habitual factor is that most pilots simply have a preferred direction for rolling, snapping, or a preferred "sight picture" (ie, always show the canopy first when rolling). The Contra very effectively eliminates assymetries in the plane from spiral airflow, torque, etc....but it does not eliminate ergonomic assymetries and pilot preferences. The science behind all of these ideas is easy enough to research, and in my opinion, the only aspect for debate is to what degree it affects our discipline.

If an airplane is trimmed to fly straight and level, and exhibits positive stability (in both pitch and yaw), are not the sum of the vector forces such that the net value is "1G" of lift? 1G being the amount of lift needed to overcome gravity. If the geometric configuration (and airspeed) of the plane is not changed, that 1G lift exists no matter what the orientation of the plane is......and that means barring no other changes, the plane will move to the canopy in uplines, downlines, and KE flight. The airplane does not know what attitude or orientation it is flying with, and has zero capacity to turn off the lift being produced. It is very clear to me that minimizing incidences (downthrust, positive in the wing, negative in the stab, etc) and reducing wingloading are effective at minimizing the pull to the canopy caused by 1G......but minimizing incidences and wingloading do not eliminate the pull to the canopy. That said, I have (and have flown other) planes that exhibit zero movement to the canopy in uplines and KE. The zero movement is not the product of the wings being unloaded, or not producing lift in a given attitude, but the product of changes or additions to the vector forces such that the net value of the 1G lift is altered and the new net value is 0G (zero G). In the vertical upline, the change that is introduced is added power......which IF downthrust is part of the setup will impart movement to the belly....and this also assumes constant airspeed as a change in airspeed would alter the lift from the wing as well. In KE flight, the change is the addition of beta (angle of attack in yaw), and now the fuselage is flying with some amount of slip in yaw (which is not present in level flight, uplines, or downlines). I will suggest that a properly designed fuselage in addition to producing lift in yaw also produces a slight amount of lift (-1G, negative 1 G) to the belly resulting in a net 0G trim condition when in KE. It is very easy to alter KE pitching behavior by changing the fuselage shape, or directing airflow on the fuselage......no changes to CG or incidences are required. I have flown planes that went straight down....and they did not have positive stability in pitch.....miserable to fly for pattern. With a tiny bit of down elevator mixed to low throttle, straight downlines are very possible, predictable, and consistent, and this is a product of changing the vector forces such that 0G is present (reducing the AOA of the wing to zero). My last comment on this is that the effects of 1G on a very well trimmed and setup plane can be small enough such that they are not noticeable in anything other than calm air, even with zero mixes. My Contra Bravo exhibits ZERO need for mixing (even on a 74K unknown), save a small amount of down elevator at low throttle.

Motor vs engine discussion - the science is 100% on the side of motors having more torque. And that FACT alone doesn't mean all pilots will prefer electric motors as again, ergonomics and preferences come into play - ask 10 pilots to put the throttle stick at 25, 50, and 75% (without looking at the TX), and you are likely to get 10 different answers. And the throttle curve / torque / power feel is different with different prop diameters, prop airfoils, motor design, exhaust tuning, cam timing, gearing, KV, etc. The very nature of electric motors is that they actually govern RPM to an extent.....the motor "wants" to run at a given RPM which is dictated by KV * voltage. If the actual RPM is less, the motor pulls more amps to get to that RPM, and if the RPM is more, the amps drop. This means the electric will add power whenever airspeed drops (going to a vertical climb, or adding drag with rudder or aileron inputs), and the electric will reduce power whenever airspeed increases (going into a dive). This is very different than glow which drops RPM some amount when entering a climb, and noticeably increases when going into a dive. FWIW, it is easy enough to do the math to figure out the average current draw of an electric flight - I typically average about 32 amps (~ 90 amps peak) with my geared Neu setup (single prop or Contra) for a mix of P/F13 in variable wind conditions and an average flight time of about 5:45 enter box to exit box and average discharge of 3,600 mah. This is flying at sea level - even at 1,000', the mah used drops by 5% or more (flight times stay the same). Very long slow flights in calm air can be as low as 25 amps average and very big fast flights in high winds can be as high as 40 amps average.

Motor vs engine discussion - the science is 100% on the side of the engines having the greater amount of energy available (since fuel capacity is essentially unlimited). The greatest stress caused by the 74K unknowns (especially in windy conditions) is on the pilots, then the airframes, then the powerplants, and most certainly the electrics feel the stress more than the slimers (tic). And in the case of the US NATs, electric still came out on top, and in my opinion, will continue to do so for all the positives offered by electrics. Do I anticipate some changes in electrics? Absolutely...and I also anticipate changes in airframe designs (electric or glow) for the 74K unknowns, and to better exploit the advantages a Contra system offers. Aside from the aerodynamic demands from the increased amount of KE flight and snaps, the 74K unknowns also put a premium on having a wider speed envelope available - and my personal opinion is that this ultimately favors the electric simply because a good ESC can provide more (electronic) braking than the mechanical braking action of a glow engine.

And perhaps most importantly - anothe Princess Bride quote -
Vizzini: ......INCONCEIVABLE.
Inigo Montoya: You keep using that word. I do not think it means what you think it means.

Regards,

RE: F3A Results - SPOILER
 

Just FYI the unknowns K, as flown during the 2012 EC in France, was modified to 70.
JP

RE: F3A Results - SPOILER
 

Hi Dave,

What a well written post. I enjoyed reading every word of it and it explained a lot of factors which I had thought I understood.

RE: F3A Results - SPOILER
 

I agree completely with Dave. That just seems INCONCEIVABLE!

As far as trying to make a point here, this come to mind,

Miracle Max: Have fun stormin' da castle.
Valerie: Think it'll work?
Miracle Max: It would take a miracle.

RE: F3A Results - SPOILER
 

Hi J-P,
Interesting !
Did they make a temporary rule change ? - or a 'local' rule.
Did the pilots or the jury want this or who ??

Brian

RE: F3A Results - SPOILER
 

We were told by Michael RAMEL at the Pilots and TM briefing, the right number for the unknowns was 70.
JP

RE: F3A Results - SPOILER
 

Hi J-P,
Thanks.
I assume the code will be updated/modified to reflect this.
Even 70 is on the high side.
Just being unknown makes them difficult for pilots and judges.

Brian

RE: F3A Results - SPOILER
 

I think Dave has written a very useful description and/or summary of the various benefits and tradeoffs for all of the different technology choices that are available. Thanks Dave, very helpful..

Also, I agree with an earlier poster who said that electrics are one technology advancement away from not having to worry about the energy trade-off side of the equation. However, in the interim, I did some experimenting this weekend at a contest in Toledo Ohio (USA) with a 5800mah 10s1p pack, and a pair of 5s2p 5400mah packs.
What I did was fly my Contra powered Wind S Pro way out past 200m, and flew as large as I could. I also flew with 100% ATV on my throttle to maximize motor power, and I didn't use any throttle management. It was also pretty windy too.

I flew the AMA masters pattern, which is similar to P13 as far as battery is concerned, and I think I pretty much maxed out as far as battery usage is concerned. Under these conditions I typically drew about 4200mah out of my packs, which was no trouble at all for either the 5400's or the 5800's. I typically had 15% to 25% remaining after each flight.

I flew the 5400mah packs at the Nats, so they maybe had 50 flights on them, and the 5800mah pack was new. The 5400 packs were G6 25C packs from Thunderpower, and they weighed 1190g. The 5800 pack was a Zippy 25C pack that weighed 1300g.

My Wind SPro made weight with both packs, although I was close to 5000g with the 5800mah packs. I am running with a Dave Snow Built up wing that comes in at 13.5 oz (384g) per panel, (Dave can build at 12.5 oz if he needs to..) and I am using a replacement wing tube that is about two ounces less than the stock tube, and this setup with the 5800mah pack would probably let me suck more than 4800mah per flight without too much problem.

Anyhow, based on this testing, I think that appropriate battery technology is here now that can effectively address the energy tradeoff side of the equation.

Brenner ...

RE: F3A Results - SPOILER
 

Dave,

Excellent... Thanks for helping us see light at the end of the tunnel. I need to read it at least 2 more times.

RE: F3A Results - SPOILER
 

I guess I am lucky. I only pay $25 a gallon for fuel and at 9 years old air frame is fine and I don't tinker every weekend.

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One addition to what Dave said, that probably fits under "ergonomics and habits are also factors" is the ability of the pilot to "see" when the plane is actually level in pitch and roll and pointed in the right direction. And if your plane isn't trimmed properly, you may never see it.

Jim O

RE: F3A Results - SPOILER
 

I'm still puzzled why FAI hasn't developed an Aresti catalog specifically for F3A. All these K-factors are so completely arbitrary and don't really give proper weighting to the really difficult or complex maneuvers.

RE: F3A Results - SPOILER
 

Hi Doug,
Very true.
However the K's are multipliers.
There is tho 0 to 10 range as well.
So getting a high mark is more difficult for everyone with the more complex maneuvers, and equally so.

Take gymnastics ,as seen in the last two weeks, as an example.
They have a difficulty rating system ,like our K's (and similar in scope too), but it's additive.
So in that a mark of 8 with a difficulty of 6 = a score of 14 points.

I'm not sure which is better or worse - I think ours is better.

Brian

RE: F3A Results - SPOILER
 

A complete catalog is located at http://fai-f3abackstage.blogspot.com...ting-code.html beginning on page 41. It's not the Aresti but it is a complete list for FAI (unknowns).
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RE: F3A Results - SPOILER
 

I understand Scott. My point was more that the K-factors assigned seem very arbitrary. In IMAC and full-scale competition, the K-factors are derived by assembling the components of the maneuver, so you have a much more granular determination of the K-factor, and IMO one that better reflects the difficulty of flying said maneuver. I'm NOT trying to turn this into an IMAC vs Pattern discussion. I'm just using those examples to explain my point.

RE: F3A Results - SPOILER
 

The IAC set this up and works well. I would be curious to see the keep factors if they were imac maneuvers.