I'm sorry, but it's impossible to me enter to the site. I have tested all of the forms.

Try this one:
http://www.lastortugasvilla.com/view...ate%20Bird.jpg

Thats OK davidfee, this bird it's very similar to a Pterodactyl.

Dear Angueto:
How do you laminate balsa wing skins, what glue you use .Manny thanks

Hola Fokker 38cc.
Como sos de Chubut asumo que mejor nos entendemos en castellano que en inglés.
Respondiendo a tu pregunta te cuento que para laminar las alas de foam con balsa se pueden emplear dos tipos de pegamento.
1- Cola vinílica blanca de carpintero (Tipo Fortex ó similar)
2- Cemento de contacto sin tolueno (porque el común ataca rápidamente al foam)
Yo conozco tres marcas pero pueden haber otras.
-Super 77 de 3M en aerosol (muy cara para mi gusto).
-Pegovía de Suprabond (latas de varias medidas)
-Vitecso 707 (latas de varias medidas)
Actualmente, debido al alto costo de la balsa estoy laminando las alas en cartón. Es una alternativa interesante que puedes ver paso a paso en el apartado de Técnicas en esta web:
http://www.rcnoticias.com/
Saludos.

Many thanks, i will make a try , I saw the site you recomend.
The balsa is expensive , we need alternative covering materials.I am building a Javelin , a sailplane with foam wing covered with brown paper, the lightest wing I have destroyed , I will make a new one.
Hasta la vista Jose


Muchas gracias , voy a hacer una prueba, He visto el sitio que usted recomienda. La balsa es cara , necesitamos materiales alternativos para enchapar. Yo estoy construyendo un Javelin , que es un planeador con ala de foam blanco cubierta con papel madera, el ala mas liviana que tenia se destruyo, voy a hacer otra.
See you later .Jose

PD
The glue I am using is white glue diluted with water

El pegamento que uso es la cola blanca diluida con agua ( Fortex)

Gracias Jose

Here's the site I was talking about: http://members.cox.net/moorman1/index.html

And this is one of the airplanes: http://members.cox.net/moorman1/pgvector1.htm

Hello again, continuing the suggestions, I have carried out some small modifications at design of my model. After analyzing the theme, (stability along the yaw axis) I've enlarge the plan of vertical fin.
I think I finish it in two weeks.
Greetings, Angueto.

I`m sorry but I can´t upload any images files since a new format.

Okay here's a picture of one of my older designs, it's just different cosmetically but it still has pretty much the same moments.

I did upload this the other day but it seems to have been lost.

I just posted some details on my fsw design. see the other fsw thread for details.

Schmleff

There are several drawbacks to a forward swept wing, some of which have been described in these posts, as well as others I can think of. What are the anticipated advantages, other than showing up at the field with something unusual to fly?

The principal is turbulance reduction. on straingt or rearward swept wings, the air that flows over the null zone on the front of the wing escapes at the tip, creating turbulence (tip vortices) that reduces the lift at the tip. On a fsw, the air doesn't swirl off of the tip but at the fuselage. No turbulences are created, increasing the effectivness of the wing per total area, and decreasing drag. In a nutshell, the tip is operating in cleaner air.

This is not to say that tip vortices are not present, just reduced.

There are other trans-sonic and supersonic advantages but they are of little use to us as little airplane flyers.

I am only going off of what I have studied on the subject over the years but am by no means an aerodynamicist.

On the model, I find the stall to be delayed for the wing loading, more gentle, and contorlable throughout.

Thanks by the explanation.
But, sadly I can't rise the modified views of my model to show them.[:@]
Greetins, Angueto.[img][/img]

Well for me bringing something unique and different to the field is probably the biggest part in it for me. Otherwise designing a model that's prone to unstability would be rather pointless.

For me it started when I was a kid and saw the X-29 for the first time and I thought it was the best looking airplane I'd ever seen. Now after doing lots of research I find out that the wing was only the secondary mission goal and they were really looking at the effectiveness of the close coupled canards. What's the easiest way to move the MAC forward? Sweep the wings forward. Ta-Da you've got a very short coupled airplane that's completely unstable.

Of course after much research I found that FSW's have been around since the first wings were ever swept. The main ones I found were the German JU-287 four engine jet bomber of WWII, the Hansa Jet - where they sold about 40 of them (here's a cool link: http://1000aircraftphotos.com/GeneralAv/HFB320.htm), the X-29 and now the Russian S-37: http://www.geocities.com/CapeCanaveral/9735/suclass.htm

I anticipated your answer. There is no real gain with the swept forward wing for subsonic flight except the novelty. However there is no reason such an airplane can't be made to fly with acceptable performance. As you have already observed, the X-29 is aerodynamically unstable, which was one of the goals of the project. It was designed to explore extreme maneuverability that such instability might offer and was only made possible by computers that can make it fly like it was stable from the pilots end. It is indeed a unique aircraft.

The basic problem for a FSW R/C model is that the configuration has negative lateral stability (dihedral effect). Model pilots are use to flying flat wings with close to zero lateral stability and probably can handle an aircraft that is a little unstable, although it will take constant attention. The swept back wing (L.E.) on most pattern models provides some lateral stability during positive and negative g flight without introducing any roll coupling in knife edge. Sweeping the wing forward has the opposite effect.

If you just want a sport model and are not too concerned about inverted flight performance, the suggestions already given in this thread will likely work, such as washout at the tips, and a little extra dihedral. You might also consider a top mounted wing since that location generally provides a bit of positive dihedral effect. Most things you can do to improve matters in normal flight will aggravate the situation when inverted.

Stability in pitch shouldn't be a problem since sweep doesn't affect that much. It's an interesting project. Keep us posted.

"I anticipated your answer. There is no real gain with the swept forward wing for subsonic flight except the novelty."

Not really...

Granted the forward sweep is definitely something that will attract attention. But, you also get different handling characteristics that can make for more interesting flight.

It really depends on the design of the aircraft. Of the numerous FSW aircraft I have seen thus far on these boards, they are mostly of the same design... a straight plank wing that is forward swept. The bird-of-prey was interesting though.

"The basic problem for a FSW R/C model is that the configuration has negative lateral stability (dihedral effect)."

That's easily solved... design in some anhedral (also, dihedral affects roll stability more than lateral stability). You do get the issue with altered inverted performance.... but you could say the same thing about a swept-back wing as well.

"Stability in pitch shouldn't be a problem since sweep doesn't affect that much. It's an interesting project. Keep us posted. "

Sweep alters the pitching moment of the wing.

I currently have an FSW kit in mid-design, so a lot of these issues are fresh in my mind.

I am guess I am getting a kick out of all of the negitive information about fsw.

I have a fsw that flies very slow (even though the airfoil is symetrical with a very sharp leading edge), pretty fast and is fully aerobatic. It exhibits neutral stability in all axis and lands like a kitten.

Build one, keep the wing torsionally stiff, and enjoy its mild stall.

I read an old probverb that says someting like, Those who don't think it can be done, should not disturb those who are doing it.

Schmleff

This exchange of opinions is very interesting.

Lateral stability is the engineering term for the tendency to roll away from a sideslip. This is also called dihedral effect. An airplane has no other stability mode around the roll axis. anhedral is the opposite to what is needed with a forward sweep. Anhedral is sometimes used with swept back wings because the additional lateral stability due to the sweep is more than desired. Forward sweep needs more dihedral not less to give the same reaction.

A swept back wing that is flat will respond as if it had dihedral in both normal and inverted flight. However it dosen't exhibit roll coupling in knife edge flight because the wing is not producing any lift. A swept forward wing that is flat will have negative dihedral effect both upright and inverted. This could indeed make for more interesting flight.

With both forward and rearward swept wings, if the tail moment is related to the mac, the longitudinal stability will be similar. There could be some effect on the moment coeficient due to spanwise flow, but it will not be large.

My thoughts exactly.

One big thing to keep in mind in an FSW craft is that the stall begins at the ROOT, not the tips. This alone makes for interesting handling characteristics, and it's worth getting to experience it.

Common maneuvers are just that... not to say that an experienced aerobat pilot is boring (nor his aircraft)... but there are different maneuvers to do with craft that don't look like an Edge or a Cap. Some that you cannot do with an Edge or Cap (I'm pondering my own design as I write this, so I'm just writing from the hip, so to speak... please don't quiz me!).

By the way... like some of the others here have already shared... I LOVE the X-29. Beautiful aircraft. Of course, I also love F-5's and T-38's... see a pattern?

Sorry Lou... It's 5PM on a friday.. I'm getting my terms mixed up!#$#@

I was thinking with my fingers and not my head.

"A swept back wing that is flat will respond as if it had dihedral in both normal and inverted flight. However it dosen't exhibit roll coupling in knife edge flight because the wing is not producing any lift. A swept forward wing that is flat will have negative dihedral effect both upright and inverted. This could indeed make for more interesting flight."

The FSW should perform about the same in knife edge if there is no lift (assuming a straight wing). Getting into and out of the maneuver is what gets interesting.

"There could be some effect on the moment coeficient due to spanwise flow, but it will not be large."

Depends on how much sweep you have... I'm thinking in terms of X-29-type sweep. On a forward swept wing the tips are loaded more than the root (depending on inner wing geometry).

Personally - I don't think a FSW design makes for a very good aerobatic airplane. Just for the simple fact that the inherent design doesn't allow it to perform snaps or spins. And besides the dihedral added to improve stability would be a hindrance to inverted flight.

Now just a note - that is what I've heard in theory and would love to be proven wrong.

On the other hand I don't understand why more full scale designers don't use this type of planform. For them the main benefit would be that it moves the main wing spar behind the passenger compartment which is usually a major handicap for light airplanes.

Two words... "Structural Divergence"

That's the reason... case closed. When you sweep a wing forward, the structural divergence speed goes down really really fast. If you don't know what structural divergece is... basically it's when your wings get ripped off due to an extreme case of flutter. That's a very good reason NOT to sweep a wing forward.

Models can have the same issue. The wing needs to be very stiff to resist this aeroelastic effect. Raising the stiffness of the wing raises the structural divergence speed.

By the way, as far as maneuvers go... you can do different maneuvers in different aircraft.

The best example that I can come up with is this: there is no way that a CAP (or similar aerobat) could perform a "Herbst Turn". It would be physically impossible because of the way that a CAP is designed.

If you don't know what a Herbst Turn is, look here:

http://www.dfrc.nasa.gov/gallery/mov...M-0036-03.html

The diagrams on this page make it a bit easier to visualize:

http://www.dfrc.nasa.gov/Research/HARV/rd.html

Another cool one is the Mongoose:

http://www.dfrc.nasa.gov/gallery/mov...M-0036-05.html

Look at that stuff and tell me that you can't be aerobatic with a swept wing. For FSW-specific stuff, try looking here:

http://www.dfrc.nasa.gov/gallery/movie/X-29/index.html