daggets

i ll try... i m not good for that...

computermonkey

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Sorry to here about the lost of your new plane.

Huang

My Feedback: (27)

Thanks daggets!

MX240

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I had a Curure in the 70's.
I flew it in the pattern wars.
It was the rage at the time with the upside down stab.
One ugly airplane. Lol

bjr_93tz

All this talk, got me excited about my Curare again (pictured wit the ASP).

Just got a new OS75AX for it as the old ASP.75 was well past it's used by date and got in 3 flights with it yesterday afternoon (12K static with APC 11x9). Lovely plane to fly.

BTW, it did one flight with a Scorpion 4035-400 on 10S, 11x9APC, CC85HV ESC (about 13.5k static) and the power was good but lacked that top end oomph it had with the .75, the extra 1.5 lbs of weight may have been an issue too??

pvogel

Based on the PMs and e-mails this morning, there seems to some confusion.

The Curare DID NOT FAIL, my griffin did, I was replying to Chris' query regarding my "dearly departed" comment.

I won't get to maiden the Curare before this weekend, the construction is quite strong!
The griffin is a modern pattern plane, all composite.

Peter+

computermonkey

My Feedback: (90)

Ahhhhhh, yes I would say there was confusion on my part.

doxilia

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Peter,

how does an all composite modern pattern plane crack at the edge of the wing tube?

There must have been severe weakening going on in the foam core (I assume wings were foam) or the design of the framed up wing must have had some issues.

Always interesting to see how models come apart in flight. When they touch terra firma in abrupt ways, well, that's all together different.

David

RCBruski65

My Feedback: (44)

The wings are composite and it sound like there is too much force on the spot where the wing tubes end. It needs some more structure to spread the load around instead of in the one spot. It sounds like it has happened on a few.

pvogel

I will try.

pvogel

See attached picture...

Peter+

stuntflyr

Hi Peter,
I saw the Griffin in the 3DHS ads and it looks very nice. Too bad, sorry to hear about that.
Thread creep is scaring the Curare guys.
Chris...

pvogel

Got to maiden my Curare this weekend :-) Sorry, no video, but I'll make an effort to get some soon.

First of all it flew nearly perfectly upon takeoff, the setup suggestions from Hanno are dead-on. Landing in landing mode (flaps down, ailerons both up, elevators down 4 degrees) is SMOOOOOTH. My only complaint there is that the amount of aileron deflection makes the ailerons much less effective at correcting little bumps from wind. It's not as fast as I would like (pace is more like a modern pattern plane) despite the slightly higher KV of my motor vs. the recommended LiPolice motor I'm going to have to figure out what's different there... Stall turns are difficult to get right, but I don't have enough rudder deflection yet (I'm currently maxed out at about 50mm each direction) so I'll have to get a longer servo horn for the rudder since I'm bottomed out on the rudder side and still don't have enough throw. It's definitely different than a modern pattern ship, but it's fun!

Now I gotta figure out a routine for the classic contest coming up this weekend!

Peter+

computermonkey

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Nice

Huang

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Awesome, Congrats on the Maiden!!

Peter what prop are you on, APC 13x8E running 6S on 4025-10? Can you share your setup and watt meter / tach info if available? (watts / amps / rpms)

My guess is you could go to 13x10 or 12x12 to get more speed out of your setup. It will still probably not be as fast as a glow short stroke version at 15k+ rpm, but should match a long stroke or YS-91 4C on the same prop at around 11k rpm.

Hanno surely did a great job on this one, electric or glow! I would just try landings without the ailerons deflected up, it takes away a lot of authority (but does land with the nose high rollout which looks cool). The Curare and most classic pattern planes lands so smooth and easy I don't even think flaps are necessary.

And videos please!!

speedracerntrixie

My Feedback: (29)

David, where the wing tube ends it creates a stress riser. This means that most wing flex is going to concentrate the load to this small section. The fix would be to add a CF spar cap out farhter then the tube so that it would spread the load out. This is one of the things I don't care too much about the current trend in pattern. The airplanes are getting bigger ( The fuse on most current designs are the same size as most 30% to 33% aerobats ) but the weight limit remains. IMO this means fragile airplanes. Not in it's self a big issue except that pattern judges want to see lightning fast snaps. At least the ones that judged the last contest I flew did. Seems to me it all adds up to a recipe for disaster. Not to derail the topic, if we think this merits a thread maybe we could start one.

MTK

Dave, there is a thread on the Electric PatternForum where this was discussed a bit. Actually the wings are hollow composite on the Griffin. Many full 2 meter models come built that way and they are plenty strong enough for the task at hand for any pattern type maneuvers we do today.

In this particular case, Chris Moon (Mr F3AU) showed the original sample model and the newest models shipped to his company. The original sample Chris has for evaluation (about 2 years old) has a glassed balsa spar. Turns out Xtreme Composit the maker changed the spar from glassed balsa to foam. Failed wings were inevitable. Xtreme Composit is going to make good on all of the failed models.

Standard foam/balsa composite wings used in Curare and so many of the vintage pattern models shouldn't suffer the same fate.But they mightif the treatment Shaun discusses isn't followed. Additional glass or carbon area to surround the end of the tube socket is a good idea, for the very few vintage models with plug in wings. Or for single piece wings, a layer of glass on the inside of bottom skins to surround the retract cutouts.It doesn't need to be elaborate or heavy and it isn't the only solution that works. I used to use 3 ounce cloth back in the 80's with about 1 1/2" overhang all around and that seemed to be safe. Of course, learned that lesson the hard way on a foam wing covered with, believe it of not, 3/32" contest balsa with a glass finish...wasn't enough to keep the bottom skin from cracking.

On the other hand, built up wings were never an issue as i recall.

doxilia

My Feedback: (3)

Matt,

your post and reply to my question is actually very timely. Thanks for the info. I know you AMA pattern guys (especially you) are very familiar with CF wing tubes, so if I may, I have a question:

I'm working on the re-structuring of a 1980's 60 2-stroke classic - for levity, convenience and ease of build. For that period, the model is rather large (60.5" length, 66.5" span) and weighed over 9 lbs!. I'm aiming for a model at 8 lbs all up wet or less. The original has a one piece wing but as I was studying it and with the modifications I have in mind, a two piece plug-in wing makes much more sense. Access to the model will be primarily from an underside hatch which is flat the length of the fuse (cowl to rudder TE). I'm setting up the model for a vertically mounted rear exhaust engine with pipe running through a glass canopy section and continuing into what will be a sheeted built up turtle deck (i.e., no foam). The deck will have a half round recessed glassed section to cradle the pipe. If you are familiar with the Bootlegger, the setup is similar but there is an angled floor (about 9 degrees) from firewall to exit at top. I plan to also make part of the pipe floor (the front part under the canopy) removable (1/8" lite ply) to access the tank (there is no other sensible way to reach it otherwise) and possibly battery pack (if installed behind the FW - that will depend on balance).

Anyhow, that's really a prelude to my question. The model spans 66.5" and each plug-in panel would be 31.7" in span (fuse side to tip). I was thinking of using a 26" long 7/8" OD CF wing tube. The tube runs just forward of the CG and the main landing gear (the mains wells just graze the tube sleeve). The wing has strong sweep (both LE and TE taper) so the tube runs at about 30% of the root chord at the center of the model to about 20% of the chord where it ends.

Do you think a 13" CF 7/8" tube section into each 31.7" panel is sufficient for the flying stresses as well as landing force on retracts? That's a little over 33% of span support by the tube. Longer? Shorter?

Also, other than a 1/8" lite ply rib section at the end of the tube and some CF reinforcement above and below it, do I need any other structural support? I am planing on running CF flat spars recessed into the core in two spots on the underside and along the strut line on the top. This all under 1/32" (note not 3/32"!) balsa skins (literally).

The tube currently ends about 2.5" outboard of the edge of the retract mount plates (which I actually moved outboard a tad since the stance struck me as very narrow originally).

Apologies in advance for the detour on the thread but since it seemed we were already discussing wing tubes and composite failures, I thought it might be timely. A reply via PM (or here - whichever seems preferable) would be much appreciated.

Thanks, David

MTK

Dave,
It's a good set of general questions and the answers should be of interest to others so I decided to post it rather than PM. My alswers are not the only possibilities of course. These have worked well for me for decades so I always use them with an eye open for lightness, noise suppressionand strength, always.....

First, on the length of the wing tube....The 13" x 7/8" CF tube into each panel will be more than enough. It will handle whatever landing loadsyou mayplace on it, eventhough the skins are 1/32". I assume that all cut outs will be inside the 13" socket length. If not, either strips of .007" carbon laminate, or subspars (explained below) should be used out beyond the furthest cut out, likely the servo. BTW, for what it's worth, the 7/8" wing joiner is plenty strong enough even for a piped DLE55 hauling the model. My latest design is set-up with a 7/8 wing joiner and sports a piped DLE55 up front (around 6 HP) some 1150 squares of wing area. Wings are not heavy by any standard...around 15 ounces per panel RTF, all paint. Except skins also included carbon veil inside for strength, stiffness and lightness.

On joiner position, the swept wing is more of a challenge. Can you re-cut the socket holes? 30% back of the LE at the root might be okay but it might be marginally okay, because of the sweep. Your CG will more than likely be well behind of the socket. Try to get the sockets centered on the CG, even if they are located aft of the wing high point. Your CG will most likely be located at 25%-30% of the MAC, which, on a swept wing locates it well aft of the wing LE at the root

Let me suggest that you use 1/32" 6-8 lb density stock rather than contest balsa. Each sheet shouldn't weigh more than25 grams for the size wing you are making. This balsa size is fine for full blown 2meter pattern wings also, but we generally don't use retracts in the wings any longer. Plenty of strength for filght loads as long as some judicious glass or carbon is used on the end of the socket as per Shawn's explanation.

If you want to make the CF wing joiner shorter, you can. The way I build foam wings is a little different than most. I shorten the sockets on 2meter stuff to include around 10-11" of CF wing joiner. BUT, I also add 1/8" balsa subspars centered on each socket and extending beyond the end of the socket 4" or so.A 3" square of 2ounce glassis added on bias stradling the socket's end and the sub spar extensions. The stress riser is brought that much further out and beyond the servo cutout.

You can also make a two-piece plug together one piece wing. Years ago Imodified a full 2 meter wing that was normally a one-piece into a two piece plug together type. The amount of CF wing joiner I used was a total of 15" which meant only 71/2" of CF tube into each panel. But the sub spars were still extended out beyond the servo cut out. The subspars also extend from the socket surface up to the skins, forming "I" beam structurewith the skins. The min depth that I've used is 1/4"; smaller than that probably defeats the purpose so on your wings, you need to have enough room in your foam

I am not a fanand do not use the false ribs at the socket ends. It isn't as mechanically sound to do it that way and I've seen sockets loosen over time from vibes. But on a smaller, lighter model, it's probably okay, just be forewarned. Also, as mentioned above, you might not have enough foam thickness to accomodate anything else but a false rib

On pipe supports,I always soft mount my pipes at their approximate CG, even for hard mounted engines. I use a single lord mount like a Dave Brown, and a tie wrap. My pipes are not allowed to touch any part of the airframe excepting the soft mount. This treatment minimizes any other structure surrounding the pipe. In your set-up, I think your lite ply pipe half round might be noisy even if lined with rubber.

If there are specific details, maybe we can take that off line with PMs

rodders

Hello
I'm watching this to see how the artf curare is turning out. I'm thinking of getting one.

I'm finding pages of unrelated stuff on here.
So far, its had one wing failure which appeared to be on the curare and now its talking about construction of other planes.

With all due respect can you keep ( this thread) it about the artf curare and open another thread for the other stuff. Nice as the general chat is, its now a mile off the subject.

Regards
Rodders

RCBruski65

My Feedback: (44)

The wing failure was not on the curare.

doxilia

My Feedback: (3)

Matt,

thanks for your thoughtful reply. Given the latest post, I'll take it offline and reply in a PM (or via email) later.

David

willyuk

Hi Jon, and all other curare fans, inspired by your build I am thinking of putting together one of these. I am in the process of gathering as much info as I can before I start.
Does anyone have a translation of the notes that Hanno put together? I speak no german and would struggle to Translate using google! I would think that an english version would be a godsend for a lot of builders.
cheers
Al

Jon Wold

Hi, I'm sorry I won't have time to make a translated PDF, but I can post some key point here.
(Here's the link to the German PDF: http://www.aerowold.com/wp-content/u...elltipps-1.pdf )

Teil 1 (Part 1) is an introduction. It states that Hanno has test flown and tuned the Schweighofer Curare perfectly so that with these templates and tips, any pilot can achieve the performance the Curare as 8 times TOC champion is capable of.

To measure the correct CG without having the wing attached, you can balance the plane at 58 mm behind the fuselage former as shown in the picture. Regardless of equipment in the wing, this will provide the correct balance point.

"Einstellwerte für Quer, Hoch, Seite, Flaps an CURARE-E" means settings for Aileron, Elevator, Rudder and Flaps, specifically for the electric version, and using the CG point described earlier.
You must add a 1,6 mm shim to the upper part of the engine mount to achieve the proper motor thrust for this CG setting. (With the CG this far back, this is essential for proper performance)

Notes for the the table showing all the different rates: The Capital letters L, R, and so on mean the stick direction on your radio. L (Links) is Left, R (Rechts) is Right, H (Hoch) is Up, U (Unten) is Down.
Aileron differential is 35 % less down than up.

There are three dual rates or flight modes set up. Gros (Very sensitive, big throws for show flyging) Mittel (Normal throws for F3A) and Klein (Small throws, 3 rolls in 5 seconds).

There are also various rudder/aileron and elevator mixes as well as the flap settings. The key point here is to acheive neutral knife edge and proper trim when using flaps for landing. The settings speak for themselves, provided you know what is what in German:
Quer/Querruder: Aileron
Hohenruder: Elevator
Seitenruder: Rudder
Gas: Throttle
Leerlauf: Idle
Rechts: right
Tief: down

Example: Landing setting: 13 % up for both ailerons, 30 % down flaps, 4 % down flap->elevator mix.
Throttle (K1) mix is 1 % down elevator from half throttle to idle.

The templates should be printed, cut to shape and glued to depron plates. As an indicator guide, you tape a 15 cm long and 1 mm thick steel rod to the control surface and it will allow you to accurately measure the correct throw.

Not stated in the manual, but noted by Hanno, is that for the glow-powered version the wing dihedral is correct, but for the electric version without the heavy tuned pipe and with the battery high in the fuselage, it needs a very slight increase in dihedral. This is achieved by adding a very small wooden shim to the bottom of the wing joint when joining the wings.

Using the dual rates in different flight modes:

- High Rate for AIL/ELE/RUD for show flyging
- RC1/F3A precision flyging: AIL middle rate, Elevator low rate, Rudder High rate
- Square manouvers: AIL middle rate, Elevator low rate, SnapFlaps active
- Spin: Ail middle rate, Elevator middle rate, Rudder low rate
- Avalanche and snaps: Aileron middle rate, Elevator Middle or low rate, Rudder low rate, Snap Flaps active
- Landing: Aileron Middle rate, Elevator Low or middle rate, rudder high rate, Ailerons up and flaps down as pr. the table of throws and mixes.

I find these settings too sensitive on the ailerons, but that is a matter of personal taste.

computermonkey

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Jon thank very much.