Bryan, of course I couldn't fly old designs in the current pattern. You're not flying the Shinden anymore, are you?

I'll say spending too much time on trimming to the impossible level of perfection at the expense of learning flying skills is retarded, to use your word.

Good to see that your earlier "truth" about strakes was then replaced by a newer "truth". I'm sure next year there will be the next "truth".

ARF's are now the way of life in pattern. There are less expensive ones, ie. Osiris, Vanquish, etc. Then there are the more expensive ARF's like Comp ARF, Oxai, etc. I'm just glad that they are available at their level of quality. I wonder just how many would be flying pattern if we still all had to build our models?

I also don't see why adding a fin or a strake to a model is all that bad if it does fix the issue trying to be resolved? It's really no different then changing the design.

Honestly, I do respect what you do, Bryan. I just think that you're taking it a bit too far. Just an opinion.

I've been setting thrust line/reference line on my fuses over the years by drawing the line from the effective thrust point (center of the prop hub) through the stab center. In other words, I place my stab CL on the reference line to make things easier, but plus or minus 1 inch makes no difference on a typically tailed pattern model, regardless. The fuse attitude is chosen when this technique is used. I prefer the fuse to fly neutral, neither tail high nor tail low. The stab is set at zero and typically I use fixed stabs, but not always. Temptress and Aesthesis have fixed stabs but Delta, my latest, has adjustable. The wing is set from the reference line

Years ago when we had all glass fuses, a sewing thread was stretched from the spinner center to the tail, inside the fuse, and the line was transferred to the fuse outside surface accordingly. This idea came from a guy who was as fine a builder as I have come across. As fuses became opaque, a laser line on the fuse outside surface works almost as well but not quite. The better method is to use a height gauge. I purchased a height gauge 25 years ago and it has served well in pattern set-up over the decades, along with a flat surface. The great thing about a height gauge is that once you have the fuse attitude fixed and fin vertical (height gauge establishes fin vertical) the stab and wing locations can be scribed on the fuse sides precisely within a mil or two. Of course, the thinnest pencil mark is around 10 mils thick and that's quite close enough for the precision we seek

BTW- I applaud Bryan's efforts to make this rather essoteric subject more undestandable to everyone. I don't recall anybody else stepping up to do a treatise of the subject as Bryan has done, although some folks have done a few things. He is passionate about the subject of perfect trim and I've had conversations with him about it over the years. We don't always agree on everything but do on most regarding trim.

Some, myself included, played with aft CG, as far aft as 40% MAC. I didn't like the model's severe tuck to belly and uncertain directionality. But other aspects of an aft CG were rather good. I arrived at more fore CG as a matter of developing what a model needed, the best compromise if you will. I don't set the CG at 25% MAC and forget it tho. For the TVC I design in, 30% MAC is more desirable. As Dave sez, there are several ways of doing things and another BTW, everything we do is a compromise

If your wing is positive to that line, then you are effectively building in downthrust. In a vertical line the wing has to be at zero or near zero angle of attack. So the incidence angle is your downthrust angle. I've never seen a true 0 - 0 - 0 design work.

It's sort of funny. My first real pattern plane, a Phoenix 6, had no side thrust. Now my current one, the Nuance, has none. Slightly different reasons though!

I agree, everything is a compromise when it comes to trimming. And there are certainly many ways to attack the problem. Please everyone note, I'm agreeing with DaveL!

Hahaha, I can SEE Harry saying that. He was a great guy to be around once you got to know him!

Verne

A couple points -

IF Joe tweaks his stab/elevators and it fixes his KE problem, the tweak will result in zero adverse trim changes and will not compromise a single maneuver up to and including FAI. If the tweak doesn't fix the problem, them something else is the culprit (again, I don't advise the tweak until all other geometric / trim consideration are addressed first).

I don't fly around trim problems.....bad use of my limited brain power I'd have never cut a wing in half 4 times so I could fly around a roll coupling issue or any other problematic trim setups. I never use a Pmix or aerodynamic device that does not make the plane fly better - and by better I mean the same quality maneuver can be replicated with reduced pilot workload. And the Pmix is the last resort.

I don't remember the year (Brian may remember), but some number of years ago, I flew with Bryan at a practice field at the NATS (I think it was Kokomo), and I got a flight on his plane. Trim condition on the plane was superb - straight KE, straight verticals, no bad behavior. Except.....I found the plane very touchy.....it was for me very tailheavy (but not unlike many setups I have and continue to see). I know since that time, Bryan has been setting up his planes with a more forward CG, and while I have not flown one of his planes recently, I am sure the forward CG setup is at least as good or better than the tailheavy setup (otherwise the tailheavy setup would still be used).

In 2008, I was extremely happen with the trim on my Bravo, and it had zero aerodynamic devices on it. It began sprouting aerodevices when the schedules changed and increased the demand on the planes. I tested many aerodevices to get the performance improvements I wanted, and if I had the time, I'd build an entirely new plane, but I don't have that time....in part because I spend it practicing instead. I've helped trimmed many different designs using my methods and found that the same size does not fit all...the idea that one trim technique or process is equally suited for all designs is nonsense......and suggesting a particular design is flawed or junk if it doesn't respond to a particular trim process is also nonsense......different planes have different strengths / weaknessess which are very often the deliberate choice of the designer based on what they choose to prioritize. And pilots can choose to fly designs which are best suited to their style / strengths / weaknesses. I have spent a limited time trimming Hebert designs....quite simply they have never been flown in the Northeast US in substantial numbers, so I've not spent much time trimming them.

So far as the spiral airflow theory......how much effect spiral airflow has on a design can and certainly does vary with the design. But...having flown F3P foamies and F3A planes with single and Contra setups, spiral airflow is absolutely real. I would never suggest there is only one way to design or trim for it.

Again, I took a pair of identical Bravos and changed 1 to a Contra. In steady state low beta KE flight (thus negating PFactor and gyroscopic precession), the single prop needs the tweak in the stab to KE straight while the Contra needs no tweak. On the Bravo (and many other designs), I've yet to experience a negative effect from tweaking the stab (to the extent needed to fix the KE assymetry). From my experience with the Bravos, I find it very unlikely that a single design plane will fly equally well with a single prop and Contra using the same trim setup. It is possible that such a design exists now, or may exists in the future, but I find that possibility unlikely.

Hey Tony!!! Looks like you, Matt, Bryan, and I all agree about an aft CG being BAD!!!!

Regards,

Ok, I'm going to ask a question about Joe's set-up now for my own education: is it a good fix to separate the elevator halves and actuate them with 2 servos to achieve differential trim? All other options except CG perhaps are closed since wing and stab incidences are fixed. Please am I missing something else one might do in this set-up to improve upon the stated OP problem? Thanks for this terrific discussion, you guys Rock!

Yea Verne, Harry had a lot more sayings, most of which I cannot post here! I learned an awful lot from that guy. Wish I could go flying with him again.

how far aft is "Aft"? (To the neutral pitch stability point or further)
What is the reason for downthrust?

Point was that not too long ago there were models on the market sporting 1 degree positive in the wing, 1-2 degrees negative in the thrust, as much as 4 degrees right thrust, and maybe zero in the stab. Even now, there are sport-batic models and certain IMAC types that sport funky angular combinations.....

In my set-up, I prefer zero down thrust (but use a couple degrees right thrust since I don't have a contar) and maybe 1/3 degree positive in the wing with slight adjustment to either thrust or wing to get the best envelope I can. I don't consider it an effective downthrust tho. My wing is simply at slightly positive aoa relative to my reference line.....but in reality, it makes zero difference to the plane or to the judge for that matter.

Well, Dave, it was 2003, if memory serves. Kokomo it was, Blue Angels airfield. You flew the Quest, I think, which was actually designed for artistic aerobatics, not pattern. It WAS one twitchy sonuvagun. You also flew my Patriot, as did your Dad. We had some good times that year, flew straight till dark-thirty! Memories like that are why I continue to fly pattern.

Brian

Dave , Yes it was a tail heavy Quest,
That airplane was the worst flying pattern plane I ever designed. But it did more to teach me trimming than any of the others.

That season we had a 1.5 snap to two of two reverse I remember not being able to do that maneuver. Todd Blose flew it and said dude you use elevator to snap? (he was flying the Hyde out. so I tried it ,,it worked no elevator but, I knew that wasn`t right. So i went down that rabit hole, and figured out it was tail heavy, Way too tail heavy. I now know why and how I got bamboozled into flying it like that.
I didn`t always believe mix was bad, I learned how to eliminate them, through the design and trim process , out came the Shinden darn good flying airplane
I had three mixes and 3 flight conditions to fly the quest, I had to land it with spoilerons, use spoilerons on the hourglass it was also the last year I made the finals I think. I had to fly Big Fast and Out like Chip did in the worlds last year , just to keep in on track, it worked me to death!

ZN line contracted to kit the QUest But I was so dissapointed I could not get it flying right I never did kit it , I still have the plug.
and I`m thinking of bringng it back.
Eventualy I figured out why it flew so bad a year later, and Fixed it it flew Great after that ,till it crashed!
It`s my favorite airplane I have ever designed to this day (other than the Alferma)


Tony actually
I planned on flying my Shinden this year, the patterns are right in it`s wheel house I`ve yet to fly a better purer design. it rolls so easy,
But Matt F. needed an airplane so I let him use it.
Brett is stealing my (his) Bipe. soI`ll fly my trusty proto Valiant as normal I haven`t even flown yet this year. other than Bipe trimming.

I have a new trim guide being developed as we speak it`s a 4 page guide that answers all the questions on trimming like
If this is what the airplane is doing( see a-r for the fix) 15 possible problems 20 possible corrections.
it will be full size copy paper front and back double plastic laminated for durability, and the flight box.
it will also cover Myths, design flaws, with easy to follow instructions you will not have to read through a article to glean the fixes.

Watch my website for details
Enjoyed it.
Bryan

Great Stuff!!!

The part I hate about mixes it that they show up in bads places usually at a different point in the sequence. I'm finding that out with my DeJaVu. Flies P great! This plane hates the F sequence!!! The rear CG and the mixes have up the work load and I hated it.

I've been in some great discussion with Bryan on the issue and some of my own thoughts. I'm hoping to test in the next few days. Bottum line to get the C/G were I needed it. I moved the wing back 1 1/4 inch. This is all on the plane that I won the NATS with last year. It was great for Masters, but doesn't like the demands of F3A. So yes I'm making changes to make the plane fly better. Moving the wing may sound crazy, but aren't we all crazy in our own way!! LOL
I was at 33-35% MAC. Now I'm in the 20-25% MAC.

Tony I do remember the bipe you flew in '89 Team Trails. That was my first Team Selection. I remember watching all the mixes in that plane while you were preparing for your flight. That was crazy, but it worked.

Just a reminder, why I did it . http://www.rcuniverse.com/forum/m_93..._2/key_/tm.htm
Tony some think it`s retarded to put a 2000.00 $ contra drive on to eliminate mixes then add new ones to compensate for the contra!
Without the proper airplane set up it`s impossible to learn to fly it correctly no matter what system is used ,you just learn to fly around it through practice ,and there is something to be said for that.

Yes ,There is more than one way to skin a cat, I just think I have the best ,most repeatable way , I can tell you exactly how it`s done ,Plus, it don`t hurt the cat! It just hurts my finishes at the Nat`s because I`m constantly testing. so yes. The truth evolves but it`s always based on previous truth. or the original was a Lie

Bryan

Bryan, I never put the Contra on to eliminate mixes. Putting it on did not eliminate a single mix. But it also did not make me add a single mix. I have no idea why you think it would. I'd have to say that is pretty retarded, again using your word. I don't know how you would think eliminating torque, P-factor, gyroscopic precession and spiral slipstream is not eventually a better way to fly. Maybe because it can't be driven by a YS motor! Or maybe because a Contra drive will change your trimming charts! But I do believe with continued development of airframes it will gain popularity. It simply has too many built in advantages. Right now we are installing the Contra into designs developed for many years using a single prop. It's going to take some time to develop airframes just for the Contra. This is very similar to when we switched to electric. We used designs developed for IC engines and found that a few changes for electric were in order.

I'd be willing to bet you've been beat a lot by pilots flying airplanes that are nowhere near as well trimmed as yours. I know I have. So those guys have certainly learned how to fly there lesser trimmed models correctly.

BTW, I currently use 3 mixes. Rudder to Aileron for KE trim. Rudder to Elevator for KE trim. Throttle to Elevator for downline trim. That's it. That's all I used when I had a single prop on my models and it's all I have activated for the Contra.

Hey Rick. Glad to hear you've moved the CG forward on that model. I watched a lot of them fly and almost all of them looked tail heavy to me. I tried talking to a couple of owners about that but I got nowhere. I'm sure it will fly a lot better with the CG forward.

DING! (not the end of the round)

POPCORN TIME....

I saw Dave fly his contra Bravo a few weeks ago, same day Matt flew it. Very impressive (but what can I possibly know).  What I can say is that my next pattern plane will likely be an all composite ARF; and the one after that very likely a purpose built contra drive airframe, if and when these are developed for the ARF customer.  I am not a builder so will fall short of that yardstick indefinitely; however, as a pilot challenging myself with precision aerobatics, I can and will improve (with a little help from my friends). Meanwhile, will leave the mods to the very talented and practice with single prop electrics until contra drive is more affordable and "mainstream." A lot of time honored wisdom, know how and "trimming" go into the new ARFs these days so thanks to all who have contributed that knowledge so I can spend my flying time practicing rather than trimming (taming?) a model where the wrong design compromises were made in the first place. It may not be the way it was done to date, but I believe it is more the way we roll as a sport nowadays as newcomers enjoy better and better ARF designs, values, options for their hobby dollar, IMO of course.

Tony, it was tailheavy at the NATS. I worked around it to make it fly right. It wouldn't work for F3A. I just ran out of time before the NATS to do anything with it.

Bryan,

I think you're just a perfectionist which IMHO is the whole premiss of F3A i.e. striving for that perfect 10. Now some people strive for perfection and some are happy to fly imperfect models. Their choice....

If one can reduce the pilot work load, why not do it? A no brainer if you ask me.

Cheers,
Jason.

Rick,

I've got Joe's Envision he bought from me and he wanted to try a set of passport wings on it. I just slipped them on at the current wingtube spot and had to open the front slot forward a bolt hole and make new rear sockets for the adjusters. With the T, and the cg about 1" in front of the tube (I think), it groves through F pretty good. I'm going to make a tray extension to move the pack forward more (hanging 1.5" off the front of the tray) to get the cg a bit more forward. Now if I can land with more than 10% left in my pack I wouldn't have to worry so much about my packs.

Hey Rick, I know the feeling of doing things after the Nats. Everything I've done to the Onas after the Nats would make a pretty long list. Along with new glasses and a lot more practice flying! At least you had it flying well at the Nats! Good luck with flying F3A. I'm enjoying it quite a bit now.

Hey Tony, I don`t mean to imply all this about you in particular.please dont think I`m directing this at you ,not my intent. I`m talking about the reasons I hear, given for switching to the contra in general. I respect your ability and opinions and know we think the same way on many setup issues.

P-factor, Tourque ,slip stream just don`t affect our airplanes as much as bad trimming does,It makes for great pit talk at the feild it makes us sound smart and informed if it did affect us ,anybody could torque roll , and taking off would be havoc on rudder steering and aileron trims.I would dare say these aero problems are undetectable, unless the airplane has a c/g beyond 30% mac then those issues are the least of your troubles. These wind tunnel issues are only seen in hevy wing loaded, full scale airplanes that are required to lift big loades and fly at high angles of attack ,the small thin wings ,heavy loaded REAL airplanes are not in the same catagory and we see none of the Ill effects they do in real life other than lift and flight.

Dave Lockhart ,I concider him a friend, as well as Matt K. I don`t want to offend them re reading my post I might have gottom a little Harsh, Im sorry if it was taken that way. They are some of the most dedicted and finest builder designers I know. I have learned from both fellows. They, like me, share everything they know ,I respect that. I remember The first time I saw one of Matt`s airplanes flying, he was running a webra 120 2-stroke I have not heard a airplane as quiet as that thing since. We share the same passions and all three of us have been blazing the trail on prop mods for many years. I respect them both.

Look, I love the Idea behind the Contra or I would not be spending huge sums of time and money and lack of sleep to design a airplane for it. What I`m trying to do is raise expectations on trim ,and push the development of our set up`s. In general, we settle to fast on patches.
I`ve been at the field working hard to have the best designs and best advise for triming for nearly 20 years now.it`s all I think about.
I keep notes and have notebooks full of what does and does not work, for example.

I changed the wing inc on the proto Valiant over fifty times.( these wings do not have adjusters)I documented what I observed , noted pos and neg effects moved the c/g so many times I lost count from 15% to 35% MAC back and forth many times ,Brett calles me insane!
I moved the engine thrust 28 times. this is just one design.this gave me the knowledge to prioritize the adjustments as to what really affected What, and where to start first ,or how far can you go with the setting, Hell I have been trimming my airplanes during contest for ten years ,It`s a desease LOL

The bipes, on my shark I moved the wings 38times, this meant actually cutting the fuse saddle, redrilling pin holes for wings pins,setting up articulating wing stays and on and on. The Alferma already 3 times. with multiple thrust setting and c/g settings. So if I sound hard headed I am ,like most of us [>:
But,It`s why when a guy in France or Russia Emails me with a odd trim question , I can answer it. and it`s always opposite of where his trim chart says to go.I can also tell when he is hiding what the airplane is really doing, just by requesting he give me the mixes he is using. am I saying mixing is Bad ,Yea,,how bad is a matter of opinion.

Talent can outfly Anything But guys like Joe deserve shot at learning the best information he can to help him win and have fun in Pattern.
It sucks to have a poor flying airplane and think it`s just your flying skills because the Common fix didn`t do anything or made something else worse

I tell you this Tony, you are right, Iv`e been beaten so many times by poorly trimmed airplanes I can`t count them. it does not detour me,.I am an above average Pilot and when I`m happy with the set up and I practice, only the top guys can outfly me
I have not really competed hard since 1998 when I placed 7or 8`th (don`t remember), in the FAI Nats. Dave remembers those flights, he judged them, i`ve been chasing perfection ever since ,and I think I have raised the trimming Bar to a much higher standard because if it.

Jason Yes with design building and trimming, I am a perfectionist any body who knows me can attest I get a little excited and want to share my findings
I thought it was falling of deaf Ears for a while But I`m changing the accepted standards. I stumbeled upon My setup in 1990 with the two stroke Storm design. Hell I thought everybody did It like that. I found out From Nat Penton, one of my Hero`s, zero zero was the Hot setup , and I was doing it all wrong LOL Who Knew it`s been a uphill battle ever since. because the guys winning gets to write the Rules and who can aurgue with them. It`s a hard time bucking the trends .
In 1998 with the EXAF Patriot after understanding my set up more,I started preaching hard on positive wing inc. and even gave a starting point as a rule of thumb + .5 deg, I dare say I have moved the bar! Some argude No It`s .3 +Hey Some even said they were the ones that taught it to me ! lol.
Maybe, I`ll push enough and move expectations again. I was scoffed back then on the NSRCA list for my sharp l/e and 1/2 deg pos inc.setting I didn`t mind I got to convert a couple top guys when they flew my planes, Jason Shulman being one of them I can still see his Grin! when he made his first team after multiple trys.

So I hope is didn`t ruffle any feathers My proof is in my advise and nobody has called me a liar yet LOL
It makes me feel Smart to sit on this knowledge, I try to give it away, but it seems as if it`s only worth what you pay for it, So I guess I`ll start selling it

Bryan

Hi Bryan,

Perhaps you could explain the thinking behind the extensive widgets on these models?

Cheers,
Jason.

Hello Joe,

I was just curious if the plane that got this discussion started is the Aeroworks Yak. I have been thinking about getting one.

Thanks,

Teo

I can attest to Bryan's addiction to obtaining the holy grail of design and trim...heck, he made me re-draw his design stuff more times than I can count...

But I can also attest to his results and willingness to help improve the trim quality of anyone's airplane.


-mark

Bryan, other then your second paragraph, which I don't understand at all, I get your point. I know how much you work at design and trimming. BTW, I have been telling anyone who asks me to set their wing incidence to .5 to .7 degrees positive compared to the stab for years. You know where that will put the CG if all the control surfaces are even. I never bought in to the aft CG trim theories. Even back to when I flew Phoenix 7's. So I know what you preach. But I think after you get a well trimmed Contra model flying you will see that it will be better then a well trimmed single prop model. But then again, I proved last year that a Contra doesn't automatically guarantee a win. It still takes being prepared in all aspects of this event.

Last year I flew a total of 300 flights on the Onas. I probably only had 180 or so before the Nats. That is way less then I have ever flown before a big event. Moving to F3A this year I now have over 400 practice flights in 1/2 year. Some of those flights were spent refining the set-up on the model. Most were spent trying to learn the patterns. I have a lot of catching up to do and at my age I'll never be a threat in F3A at the Nats again. But I can occasionally put a scare in to them at the local meets! It's been a lot of fun. It also reminded me that my main enjoyment in flying pattern is getting everything better. Trimming, powerplant refinement, radio set-ups and flying skill improvements are what I enjoy. The contests are sometimes secondary on my list of why I enjoy pattern flying. The Contra is just another item that has kept me interested.