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StingRay 3,5 m

Piero hat Probleme mit den grundlegenden Funktionen des Boards. PN schicken, antworten, Themen abonnieren und Benachrichtigungsoptionen einrichten, Bilder an eigene Beiträge anhängen usw. Ginge mir mit einem italienischen Board genauso. Gibt es eine englischsprachige Anleitung?
 
Hallo guys
I decided to follow Fox12 advice although it is a bit difficult to handle a German language based forum. I will write some posts to fully describe my Stingray 3.5. it will take much time to write everything so I will split the description in some posts.
First of all I desire to spend few lines to describe my main job: I own a small company in which I build c.n.c. plugs for the composite industry, mainly for the competition sailboats. The most common parts are full scale plugs of hulls and decks up to 18 m LOA… yes, my milling machine is quite big even if not big enough to machine those parts as a single piece, that is why I machine smaller sections then I glue them together. The milling centre is a 5 axis one and has a travel of 4800 x 1650 x 1200 mm. Plugs of such dimensions are obtained by milling EPS foam with a certain negative offset, then a layer of fibreglass is laminated, then a proper thickness of polyurethane paste is applied, then everything is milled again at 0 offset. Other materials I usually mill are polyurethane boards, wood, composites, aluminium. I also produce milled moulds, composite moulds and composite parts. Other field of interest are windmill blades and automotive industry.
Time ago I decided to take advantage of the technology I have in my shop to build my own airplanes models (mainly sailplanes) and I met Beppe Ghisleri (the father of Stingray) who was so kind to give me the original drawings of his well-known sailplane. I modelled the plane on a 3D CAD, milled the plugs, built the moulds and built 10 of them.
My Stingray is an heavy and strong one (more details will follow): here in the Italian Alps all the friends of mine (many of them are skilled pilots, much more than me… hum, maybe I am not skilled at all) believe it is much more funny to have a fast and full of energy plane rather than a dragonfly, although when poor thermals it seem to me to pilot a tanker. The plane is fully moulded by carbon fibre and infused epoxy resin (note: it is not the usual vacuum bagging, it is resin infusion, again more details will follow) and it is fully machined with my 5X milling centre (pretty proud of this, I do not use any hand-held tool such as the dremel to cut the parts).
Today I stop here, next step will be the fuselage description.
You may want to have a look at my FB page: https://www.facebook.com/Wikipiero/?ti=as
And at my youtube channel: https://www.youtube.com/user/wikipiero
 
My Stingray 3.5
Part 2: the fuselage and the infusion process
Fuselage as any other part of my Stingray (except the canopy base and servo covers) is laminated by resin infusion, i.e. the each layer of fibre is applied on the mould without resin, all the layers are stitched together and to the mould with a light spray glue which does not interfere with the resin, on top of the last carbon layer a sheet of peelply is applied and then a “flow media” and a flow network (composed by hoses, spirals, resin barriers, connectors) is applied on the mould, then everything is closed with a vacuum bag. All around the perimeter of the mould the vacuum is applied and the resin is injected by atmospheric pressure in the fibre. This process results in a laminate almost without air trapped inside (air is removed before the resin infusion), the amount of resin is the minimum necessary to fill all the gaps between any single fibre, all the gaps between the fibres are filled. The repeatability of the process allows a difference in weight of 0.2% between two identical parts. Typical impregnation ratio is 40 grams of resin per 100 grams of fibre. The resulting surface has no pinhole at all if multiaxial fibre is used, very few pinholes if a fabric is used. On the other side infusion does not allow to paint with 2K enamel “in the mould” even if a gelcoat can be used.
Fuselage is moulded with multiaxial, fabric and unidirectional carbon fibre, the bow is laminated with fibreglass (kewlar optional), in the bow there is a pretty strong plywood frame (c.n.c. cut, ready to be glued), in the middle of the fuse there is a plywood bracket for the rudder servo (also c.n.c. cut, ready to be assembled), rudder servo is in the middle of the fuse just after the wing trailing edge to get room for the water ballast, in the extreme stern just below the elevator there is a bay where to install the elevator servo with a plywood frame (also c.n.c. cut, ready to be assembled), the door for this bay and the canopy base are moulded by hand layup (no vacuum) on c.n.c. moulds. Canopy is thermoformed on a high quality plastic by a 3rd party company on an aluminium mould (I milled the mould) and c.n.c. cut in my shop. The fuselage is completely machined by my 5X milling centre, i.e. the canopy hole, canopy retaining holes, wing joiner holes, wing electrical connectors holes (d-sub 9 pins), elevator ball bearings pockets, elevator control arm slots, rudder axis holes are c.n.c. machined, no hand held tool is used except for light touch-up when necessary. A difference between my fuse and the most common ones is the way I glue the two halves together: infusion process permits to create inner flanges on the symmetry plane where a thin line of structural adhesive (I never use resin with microfiber or whatsoever filler to glue the parts) is applied to hold the two halve together… simple and effective.

Here is a video of a fuselage resin infusion, this is an old version when the centreboard was moulded separately: https://www.facebook.com/Wikipiero/videos/234122840671327/
Here is a video of the canopy mould milling: https://www.facebook.com/Wikipiero/videos/435098863782400/
Here is a video of the fuselage machining, again an old version, new foses are slightly different: https://www.facebook.com/Wikipiero/videos/283084029108541/
 

Fox12

User
Private message:

you make a click with the computer mouse on the name , who you will send a message ...

In my case ... you make a click with the mouse on my name ... FOX12 ... then a small window open , there you click on ... Private Nachricht .... then a big window open , in which you write your message ... if you have finished writing you click on ... Antworten ... under your message .... finished

"Antworten or Abschicken " is like send the message .

For writing private messages you must be logged in in RC Network.

Greetings Jürgen
 

Fox12

User
mail

mail

Hello Piero

you will get an e-mail correction if you find on the StingRay3.5 page abovetsbelow the page number for "Themen Optionen" ... Click... Themen abonnieren ... click ..... Benachrichtungsart - nur Benutzerkontrollzentrum .... Click... sofortige Benachrichtigung per mail .... Click..... and then "Abonnement hinzufügen " at the bottom right .... click ...

das ganze nochmals auf italienisch:
si otterrà una correzione della posta quando si fa clic sulla pagina StingRay3.5 in alto a destra del numero di pagina per "Themes Options" ... Fare clic su... Iscriviti all'argomento ... cclick ..... Tipo di notifica - solo centro di controllo utente .... Fare clic su... Conferma immediata per posta .... Fare clic su..... e quindi aggiungere l'abbonamento in basso a destra fare clic su

Gruß Jürgen
 
a question: is there somebody who can explain me how to find my replays to a private message? really can't manage this:confused:
Click on Benachrichtigen on the top of the board, then find at the left side under Private Nachrichten the folders Posteingang, Postausgang etc.
Messages you sent are in the folder Postausgang. Even your replies to messages you got from another person. Posteingang is the folder for incoming messages. Keep an eye on the limit of PM you can get and send. After 150 saved messages in the folders you have to delete some to get new ones.

I hope this may help you.
 
My Stingray 3.5
Part 3: wings
Wings are moulded by infusion technology. Each halve is a thin sandwich made by inner and outer biaxial carbon fibre, the core is unidirectional carbon fibre where the main spar is and PVC foam elsewhere. Connecting “walls” between upper and lower surface (can’t find a proper name) are c.n.c. cut from a sandwich board made by PVC core and carbon biaxial skins. Ailerons and flaps are top hinged, hinge is obtained with a kewlar strip. Everything is glued by structural adhesive. Leading edge, trailing edge, hinges, servo bays and control horns slots are c.n.c. machined.
Wing joiner is a classic unidirectional and biaxial carbon composite sandwiched with PVC foam. I can provide a c.n.c machined aluminium joiner which is a way to get one kilogram fixed ballast. The wing joiner and the wing pockets where the joiner goes are slightly tapered to obtain a perfect coupling with zero insertion force.
The extensive use of c.n.c. machining allows for a non-floating wing joiner because the joiner has no play with the wings and the fuselage. The fore alignment pin is not present, aft alignment pin is present although only to avoid damages to the electrical connectors during the assembling of the plane.
On this thread somebody asked for more details on the strength of the structure, here more details. At the beginning I used the same layup a friend of mine uses on a slightly smaller Stingray he build. As soon as I crashed the first plane I was able to use the survived wing to perform a destructive analysis. It resulted in a pretty strong wing which could be optimized removing some unnecessary unidirectional carbon. A friend of mine who is a pretty keen structural engineer specialized on composite material structures started a full FEM analysis but he never get an end because busy with other important job (this happens when you ask somebody to work for free…) so I had to follow another way: I wrote a spreadsheet which is able to calculate stresses on any stations of the beam and taking into account the anisotropic properties of composite materials, i.e. the different Young modules in compression and traction cases and it is able to calculate the best layup. This spreadsheet is a very simplified calculation model and some simplifications are arbitrary, it calculates only the bending properties and mostly have been written to keep my mind “alive”, despite all It gave good results which have been confirmed with further destructive tests (oh you know, I’m not such a great pilot).
Have a look at this video: https://www.youtube.com/watch?v=jiwYG7-5PrI
Have a look at the attached analysis report (Italian language).
 

Anhänge

Ailerons and flaps are top hinged
It seems to be typical italian, top hinged flaps. Top hinged ailerons are ok, but top hinged flaps are reduced in throw. The very most of all modern high performance gliders have bottom hinged flaps. It took many years for X-Models to change the philosophy of top hinged rudder. Bottom hinged flaps have much more travel and short landings in a limited area are much easier. Please think about it ;)
 
It seems to be typical italian, top hinged flaps. Top hinged ailerons are ok, but top hinged flaps are reduced in throw. The very most of all modern high performance gliders have bottom hinged flaps. It took many years for X-Models to change the philosophy of top hinged rudder. Bottom hinged flaps have much more travel and short landings in a limited area are much easier. Please think about it ;)
You are 100% right, but there are some reasons why my stingray is "top hinged": this is my third moulded sailplane, when I did the prototype I copied many features from a friend of mine so top hinged as per my previous sailplane, may be at thath time I did not konow the possibility to bottom hinge the alierons... then top hinged seems to be (a very little) more streamlined than the bottom hinged, this is just a tought of mine related to the separation bubble on the upper surface, I may be wrong... shurely top hinge has a better look... because I machine all the parts with a 5X c.n.c. milling centre, bottom hinge meens I have to machine both sides of the wing (servo bay on lower side and flaps slot on upper surface, this requires more time... it takes a certain amount of time to study a new kinematic (I always do this by CAM software in a very precise way) and to prepare 5x new toolpath for the bottom hinge, I spent my time to optimize something else... my flap can be deflected 45 deg downward and 15 deg upward (10 deg without any bump on the slot) with just 2 mm slot at the bottom, it is questionable if 15 deg up is necessary, anyway 45 down is good , the remaining 45 deg to reach a "full down flap" seems effective but not thath much (again I may be wrong)... I already switched to bottom hinged on another airplane I build (Ido not sell this one because it is too expensive to be built) and there is no reason why to think to switch to botom hinge also on the stingray, i.e. may be in the future...
 

Anhänge

may be at thath time I did not konow the possibility to bottom hinge the alierons... then top hinged seems to be (a very little) more streamlined than the bottom hinged, this is just a tought of mine related to the separation bubble on the upper surface,
Ailerons should be top hinged. You can keep the gap small because downward deflexion is minimal.
Flaps (that are used as an airbrake!!!) should be bottom-hinged, because upward deflexion is minimal (even smaller than down deflexion of aileron) and down-deflexion can be maximized.

About the separation-bubble I should not bother. First it occurs way more in front (usually between 40% and 50% of chord) and secondly extra drag of an separation-bubble is good because you like that when braking ...

Just my 2 cents ... ;)
 
Another advantage for bottom hinged flaps is the cross servolink departing on the topside of the wing, being not so close to the ground.
 
Nice to announce my planes will be distributed in Germany By Modellbau Pollack.
soon I will continue to give more details on my Stingray 3.5.
 
Ailerons should be top hinged. You can keep the gap small because downward deflexion is minimal.
Flaps (that are used as an airbrake!!!) should be bottom-hinged, because upward deflexion is minimal (even smaller than down deflexion of aileron) and down-deflexion can be maximized.

About the separation-bubble I should not bother. First it occurs way more in front (usually between 40% and 50% of chord) and secondly extra drag of an separation-bubble is good because you like that when braking ...

Just my 2 cents ... ;)
you are right. anyway my concerns about the separation bubble is not about where it occours, it is on where it reattaches.
 
Piero hätte seine Modell auch italienisch verstellen können. Sorry, Bostrom aber so Kommentare sind absolut überflüssig.

Freundlich an dem Modell oder ignoriere es.

Also echt...

Thanks Piero for presenting your efforts. Good luck with it.
 
Und ne englischsprachige Grundausbildung sollte durch unser tolles bildungssystem selbstverständlich sein. Ironiesmiley ;)
 
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