TOC Zlin 526 by Bonnema/Lowe
 

TOC Zlin 526 by Bonnema/Lowe!!!

There will be at least ONE "Classic TOC" event in 2011 flying airplanes/manuever schedules from the 1978 International Tournament of Champions. I always wanted to fly in the TOC and the only way this will happen is if I sponsor the contest!

Eligible airplanes include the Ed Keck Akromaster which will have foam wing/stab/turtle deck components as well as a laser cut fuse/fin/rudder available for ordering a few weeks (the first parts are being delivered this week to Chicago).

Yellow Aircraft manufactured a CAP 10B featuring pre-sheeted wing/stab/rudder which can be found NIB on Buy-Bay or via your pals. (found one from a local club member, NIB)

Great Planes and Bridi produced a Hanno Prettner designed Dalotel which is harder to find. I have plans available for the cost to copy and ship for interested parties.

The Model Aviation, February 1980, Zlin 526 designed by Mr. Ken Bonnema and Mr. Don Lowe. With my prsonal profit as the absolute LAST purpose (there will be none!!!!), I am going to ask my modeling elves to create foam wing/stab/turtle deck parts as well as laser cut fuse/fin/rudder stuff for glow and "E".

This thread will discuss the Zlin 526

AMA plan service sells the plan #00287 (2-sheets) for $21.00 less a 10% member discount. Call Greg (800) 435-9262 and order a set for you and a set for your flying buddy.

Rusty's Zlin-

Webra .91 and muffler (Buy-Bay NIB $130 - $180.00)
Dave Brown retracts
Canopy...I will ask Mr. Guerin to make a mold and ask GLOCKGUY to pull them.
Aileron/Flaps combo will be included like my Great Planes 526 project.

Time schedule:

February/March-

foam wing/stab/turtle deck design and creation
laser cut parts development

May/June-

build model #1

Get in early and let me know your interest and how many your are gonna build!

Rusty Dose
Team Futaba
Team YS Parts and Service
Crazy for Classics

RE: TOC Zlin 526 by Bonnema/Lowe
 

hmmmm I have a NIB Cap 10....

RE: TOC Zlin 526 by Bonnema/Lowe
 

Rusty, I still wonder how serious your question in the other thread actually was, but if you really want to know about the Z-526 AFS ailerons I think I can tell you:

The Z-526 AFS was a special clipped-wing version. (You mixed pictures of the AF version in your posts.) The clipping made the ailerons too small so they had to be extended inboards. There were the split flaps in the other versions, so they omitted the flaps entirely and extended the ailerons about to the point where the propwash begins. The aileron hinges are pins in the aileron nose and corresponding bushings on wing ribs. They kept the original rib/hinge and just added a second aileron part between this rib and another, more inboard rib. Adding a "parallel" linkage was very easy. Flaps are not needed for an aerobat so they saved weight and complexity. They added big wing fairings, though.

There's a [link=http://www.zlintrener.com/tipus.php?nyelv=angol]Hungarian website[/link] with a short history of the Zlin aircraft. In the "Photos" section you may find pictures of the wing structure. You may know this [link=http://richard.ferriere.free.fr/3vues/zlin526afs_3v.jpg]3-view[/link]. By the way, the wing airfoil is told to be NACA 2418 to 4412 (root to tip) with about 3 degrees washout. I suppose you don't want a scale model, anyway, so you will use a symmetric airfoil and may as well use the inner ailerons as you like.

Just for your information.

RE: TOC Zlin 526 by Bonnema/Lowe
 

TOC Zlin 526

Hey Rusty...how serious were/are you about the flaps?

UStik,

Great information and thank you for the links. As you can see by the pictures of my Great Planes Zlin 526 ARF with (2) different wing...I am quite serious about the aileron/flaps.

The photos I have found clearly show different deflections for the aileron/flap and I have accurately produced a wing to test my expectations. (See RCU thread "Classic Fundamentals...building techniques...testing the Prettner/Matt flap spoilers...)

What we have found with our toy airplanes that having the ailerons begione outside of the stab, clean up the airflow, crating a more axial, smoother roll. The challenge of cousrse, as you pointed out, is the amount of control authority for inside/outside snaps and the effect of speed and control response. I also expect to be able to control the diffential required with the inside flaps rather than the ailerons.

Additionally the flaps will be used.benefit different flight modes:

- flaps "up" for spin entry with a condition based on throttle position.
- flaps "up" for landing, creating an exaggerated nose high attitude.
- flaps coupled with elevator for tighter corners or simply "pushes" from inverted...the canalizer has proven to enhance this attitude.
- No flaperons for more axial and precise rolls.
- "All in" for snaps, variable for inside and outside.
- "Crow" for slowing down very quickly...down lines, spin entry, silly landing approaches, flying backwards on windy days.

The wing will be symmetrical. The clipped wing of the AFS will be a more precise model...not neccesarily used in the 1978 TOC...hey I can use SPA type rules!

Thanks for your interest!

Rusty Dose
Team Futaba

RE: TOC Zlin 526 by Bonnema/Lowe
 

Well,

I didn't think that the scans of these would be posted any time soon but given the effort Rusty's putting into these 90 size models, here they are. The MK versions... The last of course is the Chipmunk. Note the difference between this Zlin and the 526. This one must be a more modern version.

David.

Edit: I think I might have just found a use for my 91 FX. :D

RE: TOC Zlin 526 by Bonnema/Lowe
 

Rusty,

what do you expect the AUW of these models to be? Are 90 2-strokes going to haul the mail or just the flyers? 9 lbs or less?

More questions: the DB retracts you mention are of conventional (Pro-line) type I assume. Mr. Bonemma used scale retracts with them rotating into the wing (hard to believe they fit). Would Corsair rotating type retracts be more appropriate for the Zlin?

By the way, a plug-in wing design as with the Akromaster would also be an interesting option.

I think I just found the answer to both those questions/ideas. I plug-in wing with retracts is somewhat more complicated I suppose. Interesting that the wheels just retract partially.

David.

P.S. Here's the MA article cleaned up just a tad. The center portion of the left page is missing.

RE: TOC Zlin 526 by Bonnema/Lowe
 

Well, I stand corrected as to where the inner ailerons reached. On the Z-526 AFS they really kept the stab in clean airflow. I confused it with the later [link=http://richard.ferriere.free.fr/3vues/zlin_50_3v.jpg]Z-50[/link] where they avoided only the propwash. (David, that's the other Zlin in your pictures.) Since I'm a purist (to my regret :( ) I have to insist on simple inner and outer ailerons moving together, though. No offense meant, there is just no seperate linkage for separate movement. It's just like an elevator pushrod split on one end for two elevator halves.

If you mean the pictures you showed in the removed thread, those were optical illusions (not surprising). Your ideas on using the four wing "flaps" are very interesting, though, and surely adequate to this model. The full-size original was just the last stage in a development of aerobats which were all derived from the two-seated trainer. It was in the late sixties and it was even revolutionary back then to have clipped wings and so big ailerons. It was Zlin's answer to the requirement for faster roll rate and more snapping maneuvers.

Only very few Z-526 AFS were built (I think I read on the old Zlin website it were 18). In the seventies they replaced it with the completely new Z-50, not derived from any other type but retaining some of the 526's general layout. Wing airfoil is now symmetrical NACA 0018 to 0012 to get rid of the airfoil pitching moment and to cope with more inverted maneuvers. The ailerons are even bigger, and they are still split in two parts. I don't know of any differential movement, though, so it seems to be again for structural reasons only. By the way, the Z-50 is said to have a weak spot where the empennage (vertical tail) is mounted to the fuselage (kind of a structural bottleneck).

The Z-50 has the now common fixed landing gear with small wheels to save complexity, weight, and drag. The Z-526 AFS has the same retractable landing gear as the trainer (from the 326 series on) it's based upon. The [link=http://richard.ferriere.free.fr/3vues/zlin526afs_3v.jpg]3-view[/link] shows that it simply swings back and up around an axis in the wing nose. That was intentional not only for simplicity, I think, but also to have the wheels sticking out of the bottom and working for "unintended" belly landings done by students. (At least I think instructors wouldn't do that. Or would they? ;) )

All that may be not suitable for a TOC model, though, so it's again just for your information. [8D]

RE: TOC Zlin 526 by Bonnema/Lowe
 

TOC Zlin 526!

Good questions from Dox and UStik...

Retracts...the retracts on the full scale only partially retract, works fine and probably adds a level of safety for student landings. The Bonnema/Lowe version does NOT rotate, note complex bend over/around wing spar.

Aileron/Flap...I believe that the 526 pictured is not an optical illusion rather a functional variable deflection opportunity/unintended maybe, convenience yes! The Zlin Z-50L was flown by Dave Brown for the 1978 TOC. The Z-50L had pretty wicked pitch issues (goes violently to the belly) in knife edge...very, very common with a stab that is too high.

Consequences of a stab that is too high- The SPA "modified " models usually begin with lowering the stab! The last 2-3 years have seen anhedral stabs added to F3A models. My Oxai Beryll offered a plug in anhedral retrofit, effectively lowering stab, resulting in almost all of the pitch mix removed...less pitch to belly. Center of gravity and decalage ALWAYS impact mix and models relative flight attitude/path for "level" flight.

The target weight of Zlin/Akromaster TOC replica models? Target weight is 8 1/2 to 9 pounds less fuel, RTF. It is most interesting to see how robust classic models were built. It is possible to simplify construction and reduce weight with modern techniques...just ignoring the need to provide a level of "crash survival". Rusty's laser cutting design elf used a very clever inter-locking construction technique. I assume the Zlin will provide the same opportunities. These models do not need to hover, the fun/challenge/requirement is to actually manage "energy" throughout the sequences.

Providing an "E" version...I love "E" power, fly with higher levels of precision, have 50% more practice time due to the ability to fly at 5:30 in the morning and recognize that it must be available for the TOC replica's. The Akromaster has an "E" version consisting of plug in wings, different fuse set-up for a modest priced outrunner and removable hatch for battery access. The Zlin will be the same.

Rusty Dose
Team Futaba
Team YS Parts and Service

RE: TOC Zlin 526 by Bonnema/Lowe
 

Believe it or not, the original's inner and outer ailerons are coupled, there's no differential deflection. :D

You borrowed a very good picture of a well-known and well-kept copy of this type. Don't confuse the trim tab and the hinge rib with the aileron outline! By the way, what do you think in which kind of maneuver the airplane is? Full right ailerons, a bit left rudder and down elevator, hmm... I think that's classic full-size aerobatics, many corrections needed.

On models you try to trim and mix out any unwanted tendencies. You just have to modify the design since the old originals were by far not up to even the 1978 model TOC standard. Using the inner ailerons as multi-purpose flaps is a great idea that even keeps the look of the original. I'm not positive about the reason for the Z-50's belly pitch. It might be the low wing position as well. And please note that the original has a bit positive incidence of both wing and stab.

RE: TOC Zlin 526 by Bonnema/Lowe
 

UStik,

thanks for all the great info. On looking at your annotations I now see how the deflection of the coupled ailerons are uniform (no crow). The rib in between is the misleading visual making it appear as though they are not deflected the same amount.

With that in mind though, it's hard to visualize a stable flight pattern if the inner "flaps" are coupled to the ailerons at all times. In other words, the inner flaps are either coupled and so only full length flaperons are potentially possible (not particularly interesting), or decoupled and the surfaces act strictly as flaps (inner) and ailerons (outer). I would imagine that the coupled mode would be used for general aerobatics (i.e., no possible flaps/spoilers), while the uncoupled mode would be used for take off and landing assuming the outer ailerons provide sufficient authority.

Of course, this doesn't prevent a setup the way Rusty envisions it, but I would probably program things in a simpler way (ailerons master/flaps slave when coupled). Four servos would still be required however.

Rusty,

thanks for the answers. I would very much like a digital copy of both the Zlin and the Akromaster plans if possible to better understand how these birds are built. I imagine the production versions (produced from CAD) will differ in clever ways to simplify things and lighten things up. Interlocking is also nice!

I am also glad to hear that both will be available for E-power and plug-in wings (I see that the Zlin allows a CF tube to pass between the wheel and the retract mount). Although I'm debating on which one to build (the plans will help me decide), I may end gravitating toward one each (one for E, one for a 91 FX).

I was thinking yesterday about Ken's design and see a few changes right away that simplify things. Interesting to note that his Brushfire and Zlin use very similar construction and design. I don't particularly like the 4 bolt approach to the wing but that issue will be removed with plug-in wings. For the glow versions (I assume they'll have a single piece wing for strength), the wing LE fuse former can simply be extended allowing twin dowels to enter the former with a vertically leveled wing/fuse joint (as opposed to the plans slanted junction). Standard twin bolts in the wing TE.

The wing cores should probably be extended rearward similar in style to the stab design allowing ailerons/flaps to be cut to scale rather than use the strip ailerons on the plan. I like the honeycombing concept of the wing core but would rather use a full sheet for simplicity of construction (sectional sheeting works better when using contact cement as was done back then). It would be nice to design/cut recesses into the cores at source for servo boxes and wheel wells - I find this doubles the amount of time required to build a wing. Personally, I also can't see using mechanicals on a design like this, too much patience required (bellcranks in foam wings...! No thanks).

The hardwood engine mounts could probably be lost in favor of a radial mount for glow and standoffs for E. A stronger FW might be needed for glow (2-3 x 1/8" ply laminate - perhaps 1/4" for E and 3/8" for G).

I do like the removable foam core empennage. Is there a way to simplify the mounting yet? Perhaps there's no need. I can't see the details in the PDF you posted Rusty but Ken's design appears clever (not sure whether it's bolted from above or from below through the fuse/stab and into the fin).

There were some other thoughts but they escape me now.

Would you be able to post the complete articles (Zlin and Akromaster) so that they can be read?

TIA, David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

A couple of inverted mufflers for the 91 FX (similar should be available for the Webra's):

Bisson (better quality) and J'Tec (more scale). About $40.

David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

TOC Zlin...catch the TOC fever!!!

More good questions...

Availability of digital plans? I will not post a digitized version of the full size plans due to the copyright violation/respect to AMA and MAN currently offering the plans. Rusty's laser cutting Elf's work plan will not be posted out of respect for the "owner" of the work-Rusty's laser Elf. Very good question!

Foam wing details- I prefer to cut the aileron ut of a foam cut wing rather than carve crooked, soon to warp strip ailerons. The builder may decide to add lightening holes, servo cut-outs, secret compartments... I have found this to be very personal in nature and nice "clean" cores please most everyone. A one piece wing is lighter, makes the entire airplane stronger and is noticeably quieter than a plug-in wing. The "E" version will have a firewall, removable hatch perfect for electric.

Removable stab/fin/rudder- Not neccesary and heavy. Number of wing bolts, very personal...let the builder decide.

Maple engine mount- I have found the maple engine mount to be strong, simple, cheap and has been integrated into the Akromaster glow laser version. The "E" version has a firewall with holes.

Articles? I will post the Akromaster article from RFJ on the Akromaster thread a cleaned up version has been posted to this thread courtesy of Freebird.

Great interest, much appreciated!

Rusty Dose
Team Futaba

RE: TOC Zlin 526 by Bonnema/Lowe
 

David, all else I can contribute is my experience with a simulator model of the Z-526 AFS. The inner ailerons are commonly mistaken as flaps and not even considered as flaperons by modelers. Maybe that's because the chord length of both inner and outer ailerons is quite big and the outer ailerons alone are effective enough. That in turn is because models fly at relatively greater speed than the respective originals, so the ailerons seem/are more effective and roll movements are faster.

On a model, the coupled ailerons make for a very crisp response even at slow speed - you might like it. Deploying the inner ailerons as flaps (flaperons) keeps the aileron effect (but adds adverse yaw) while giving great drag. You won't notice an increase in lift, which is not needed, anyway. But the drag makes approach and landing really much easier. That's for wimps, a purist might argue, real men do sideslips and just fly slowly for landing. But again, you might like it. I didn't try raising the inner ailerons (spoilerons) or even crow, but I think it's overkill and would have a similar effect. I would shoot for the in-flight useages listed by Rusty, though (snap flap, inner ailerons less deflection than outer, etc.).

By the way, the original Z-526 AFS not only has cambered aifoil but also a noticeably lower wing loading than modern aerobats. So it flew "slowly" and needed big ailerons. On the other hand, its engine power was big for its time but small by current standards. Maybe it was the last aerobat of the classic age where energy conservation was the key. In this respect it might fit Rusty's specification, but I think we can't take it that literally.

Interesting is that Kenn Bonnema somewhat "defanged" the Z-526 AFS design for use as a TOC model. In addition to using a symmetric airfoil, no washout, no incidence, and narrow (strip) ailerons for the wing, he obviously flattened the fuse a bit and reduced the vertical offsets to get a more "symmetric" and "neutral" design. Not only the structure/construction reminds of his admired (by me) Brushfire design.

The original is just an old, though very nice design. Actually, it's completely asymmetric and unruly and needs a good pilot. It's feasible as a TOC model only with many "hidden" design modifications. For me, the Akromaster doesn't seem so nice but it seems to be a more symmetric and neutral design already as full-size original, about what Ken Bonnema achieved with his redesign. I would really like to hear his comments.

RE: TOC Zlin 526 by Bonnema/Lowe
 

Rusty,

plans: sounds fair and respectful. Please do post links to the purchasable plans if possible. Would ELF plans come with the short kits?

articles: I don't see FB's article to the Zlin here - post #?

UStik,

I'd like to hear Ken's thoughts too. He has been very generous in providing valuable information on the Brushfire on a thread I started some time ago. I was contemplating a tiny Brushfire for a Webra 12 RE with pipe that I have. It seems I just love to make life complicated for myself!

Actually, I look forward to my next 60 or 90 size build (whatever it may be) and get some space after a year or so of not having any!

David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

I just bought a NIB discontinued GP Cap 21. Alas... it is small (60" span).

Anyone ever built one of those?

I see two different types of rudders - the one from the 10B (curved) and what I believe is the actual 21 (angled)

David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

The cap 10b rudder is totally different from the 21, the 21 rudder comes from the CAP 20. the top pictures of the blue one, the aircraft seems to be highly modified, different rudder and cowling. Probably to bring it closer in line with the CAP 231.

Here's some information on the Mudry aircraft. in french but the pictures are nice.

[link=http://pagesperso-orange.fr/michel.bardot/historicaarp.pdf]CAP history.[/link]

RE: TOC Zlin 526 by Bonnema/Lowe
 

What is the span and length (and other specs) of the Bonnema Zlin?

RE: TOC Zlin 526 by Bonnema/Lowe
 

I sure have built one of those. It was about mine an my dad's 7 airplane build together in the early 90's. We ended up putting an OS 70 surpass on it. It was a blast to build, just really heavy. We were not the greatest builders in the world. It was like a spark plug by the time we were done with it, but it flew great. It met its end in a flat spin. :( Have fun building. It is a great kit to build from.

RE: TOC Zlin 526 by Bonnema/Lowe
 

PF,

thanks for the feedback. I've read that they have a wicked snap tendency! Perhaps just the planform of the flying surfaces. The position of the stab on a model probably doesn't help. I understand that GP went to great lengths to tame their CAP's. I've seen their 27% 232 fly and it is very nice (I'll put mine together one day). I think the 580's do very well too.

For nostalgic reasons though, I find the older CAP's are nice. I believe that GP (Bridi previously) also produced a larger glass/foam 10B prior to the 40 (60") and 60 (72") sizes. And I think that there was also an 88" 120 version! I found a nice photo of the GP 60 (72" span).

Since Gunter Hoppe entered a CAP 21 in the 1980 TOC (3 CAP's entered in total), I thought it might be an interesting design to consider. Although considerable revisions to that plan would be necessary, it might be a good starting point for an enlarged 90 size 78-80" version.

I guess the other classic 1980 TOC choice design would be the Dalotel DM-165 (6 entered in total). I'm fiddling with a 60 size plan to enlarge it for 90 size power. Probably 65" length and 70.4" span (10% larger than the 60) or thereabouts.

David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

TOC Zlin 526 discussed in the January 2010 Classic Pattern-Trader!

No way...the Classic Pattern-Trader discusses the Zlin 526 in the January 2010 issue...

Thank you for your interest!

Rusty Dose
Team Futaba
Editor, The Classic Pattern-Trader

RE: TOC Zlin 526 by Bonnema/Lowe
 

I just had to post this picture I came across.

And these...

David.

RE: TOC Zlin 526 by Bonnema/Lowe
 

Would the IM TOC Laser qualify?

RE: TOC Zlin 526 by Bonnema/Lowe
 

Zlin 526/526 AFS...short kits by Laser and Foamy!

Questions:

1. Would the IM Laser be eligible? I assume that it is at least 800 square inches, does not deviate more than 15% in any dimension and will weigh less than 18 or so pounds? Dean Koger flew an Ulery (spelling...I always get it wrong) Laser 200 in 1978 and a larger one in 1980. Lasers are cool.

2. Dox...great pictures. I have seen the Dalotel photos previously, ambitious scale model. Hanno's model, the Bridi kit of the 1980 model, is "optimized".

The laser project is on schedule. Rusty's elf "Laser" picked up the plans and gave me his initial thoughts on the "e" and glow versions. "Foamy" will receive the plans later this week.

I am in hot pursuit of the original molds for the cowl and canopy and if found will save lots and lots of time and effort. The goal for prototype #1 in glow is late June of 2010.

Rusty Dose
Team Futaba

RE: TOC Zlin 526 by Bonnema/Lowe
 

So is the Laser 200 designed by Ulrey really what Koger flew in 1978? If so is it eligable for the 2011 TOC you are planning? I will dig my plans up and see if any dates are on them. I do remember it having a geared 90 for power.

RE: TOC Zlin 526 by Bonnema/Lowe
 

Laser 200 by Ulrey/Ulery for 2011 TOC in Chicago...yep!

Wayne is a gem of a guy and freaky talented. He designed Dean Koger's Lasers for 1978 and 1980. I believe that MAN or Model Builder or Model Aviation did a constuction article.

Rusty Dose
Team Futaba