James c harrell

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I had a plane that was damaged in a bad landing and when in the process of repair I had a weird idea. I had wacthed a video of a Russian jet tha had front canards and thrust vectoring that really impressed me. Thinking along those lines I started wondering if a canard type wing on a conventional propped plane would add some manuverability. The plane I am putting this on is a Sig Something Extra and have installed a small canard type wing right behind the prop and mixed it in with the elevator. The idea is to have a type of thrust vectoring on a front propped plane. The front wings or canards as I call them are slightly smaller than the prop. I am curious as to what effect they will have on the airflow over and under the wing. I am still in the process of the final covering it and still haven't decided as to the final size of the front wings yet. I have made them to be removable and to be swicthed from stationary to mixed at a % to the elevator. Just wondering if any-one has seen or tried this before.

soarrich

My Feedback: (98)

Cessna tried it on a 177 in the 60's. The power changes played hell with the pitch setting.

TimBle

you're going to be creating havoc with airflow over the deepest chord section of the main wing.

Not only that but you will destabilise the elevator reducing its effectiveness...

does not sound like a great idea but the Something Extra does have a thick wing so maybe it won't haveany effect at all.

Mind your CG though

BMatthews

Move the CG forward a little from the normal spot for the first few flights. Other than that it's "just" a model. And who knows, you may be onto something here.

Rodney

What Mr. Matthews said, an interesting experiment that is sure to be exciting. Try it and let us know how well you like it. I'd bet that it may be worth experimenting with. We need more original thinkers like you trying and reporting on experiments, failed ones as well as those that work.

Lnewqban

Check this project out:

http://ctn.cvut.cz/ap/download.php?id=345

......and this thread about three surface models:

http://www.rcuniverse.com/forum/m_24...tm.htm#2419196

James c harrell

My Feedback: (18)

These articles are awesome! I have alot of reading to do now. I too was worried about the front set affecting the airflow of the main and elevator. On the Something Extra the elevator is slightly higher than the main wing so when I put the front ones in I put them a little lower than main wing. The front are also flat and set flat untill I hit the mix swicth. Then they only move a little with the elevator. If they don't send me into a Death roll or something I plan on mixing in a little more just to see what happens. I am blessed enough to have a field to test this thing on at my dads house that is about 700 acres or beans. Just in case. I have a little covering to do yet on the fuse and I will post a couple of pictures. Important for me to let you know I get bored with the ordinary sometimes and try something a little crazy. I do alot of building real late when everyone is asleep and crazy ideas come at 2 or 3 in the morning. But it is all for fun and sometimes- well who knows!

BMatthews

It's not so much about the canard "upsetting" the airflow but that you have to take into consideration the shift in the "wing" area in that the canard will be supplying some lift at various points and attitudes during the flight. This will result in a shift of the overall MAC of the model. That's why I suggested moving the CG ahead a little for the first flights.

A cheap but effective way to get an idea of how it'll react is to make up a small 12 or so in span all sheet balsa glider that lets you put on and take off the canard by sliding it in and out of a slot in the nose. Flat wings for this simple CG location trial test model will be fine. Balance it up using the stock layout and then see how much it alters things with the canard in place. Make it all to 0-0-0 but allow for warm breath warping of the tail and canard. Warp in just a hair of up in the elevators for the first tests so that your model is positively stable. Don't bother with dihedral for this sort of model since it SHOULD stay stable enough for simple hand glides. If it falls off and it's not just a simple wing warp to fix it then maybe cut and reglue the last 2 inches of the wing with about a 1/2 inch of dihedral to make it stable enough for test gliding. Play with some different decalage angles by warping the elevators and canard from flat to slightly "positve". For the rear that's some reflex and for the front some down. See how altering the source of pitch in these small amounts affects the stability. It may offer you some ideas for how to scale the front to rear angles. And if nothing else it'll show you what happens to the "just barely stable" point of the CG. And after it's all over it'll make a swell mobile decoration for over the bench...

James c harrell

My Feedback: (18)

Don't know why I haven't done that already! I am always making little balsa gliders and stuff with the scrap I end up with. Kind of my way of getting my son into the idea of aerodynamics. I was lucky as a kid and was raised in a Air Force family and had the chance to take JROTC in High School. The main course of study was aerodynamics. Great idea there! If I can ever finish covering this fuse I will do exactly that and get some idea of where to balance this thing. I got a feeling that the propwash is going to be rough on the servo that controls these but I really don't want the slop of a servo saver. Think I will go with a heavy control rod and a metal gear high torque servo. It isn't going to take much swing so I can set it close in on the servo side and the wing control horn.

MTK

I am doing this much to my new pattern design. Initiates straighetr airflow

Dsegal

Take a look at the Piaggio Avanti- really looks neat in the air: http://www.google.com/images?hl=en&s...io+av&gs_rfai=

James c harrell

My Feedback: (18)

Well, I finally got the fuse covered and the front canards in, linked and mixed. Almost ready to fly her. Still need to paint the engine compartment so dis-regard that in my pictures. Itook a couple of pics with up elevator and down and neutral. I have the radio set so I can let them move with the elevator or not, and I can move them independantly. The whole front set-up is also removable if I want pretty quickly. I did take some advise and moved the CG forward a little and went with my ole' faithful AX-55 for the power. Just a little nervous about the test flight as my spotter, co-pilot is in the hospital till at least Monday. I think it will wait till Wednesday, the weekly gathering of our group at my club. Plenty of advise available on Wednesdays, like it or not! Thanks again for all the help and in-sight. You all make it a little more fun and alot less confusing. I will let you know how it does. I think I will even tape it. Having some problems with the pictures. I will try on another post.

James c harrell

My Feedback: (18)

I think I got it now. Got to load them one at a time.