trying to find CG for burt rutan quickie

[aaronredbaron]

it is sort of a canard/sort of a stagger wing bipe. I am hating myself right now for dropping out of aerospace engineering, AND selling my best AE book. what is the formula that relates the center of lift for both wings and then takes into acount the overall lift force since the area's are different? can I then simply average the distance??? any idea's?

[DanSavage]

Originally posted by aaronredbaron
it is sort of a canard/sort of a stagger wing bipe. I am hating myself right now for dropping out of aerospace engineering, AND selling my best AE book. what is the formula that relates the center of lift for both wings and then takes into acount the overall lift force since the area's are different? can I then simply average the distance??? any idea's?

I know what a Rutan Quickie is. My brother Daren is building a 1/4-scale model. This should help.

However, since the canard on a quickie is actually below the wing, I'm not sure whether the wing flys through the canard's downwash.

Are you building it from scratch or from a kit?

Dan

[aaronredbaron]

it currently is powered by a OS 40 FP w/ perry pump because the fuel tank is at the CG (I think) depending how well it flies I may do a brushless conversion. since your brother is building a 1/4 scale one too maybe you could measure the CG from a constant point (trailing edge of front wing/canard, or from the firewall or whatever) also if you could give me a constant length to go from (wingspan, fuse length.. anything) I should be able to account for any variences in size. from what I have heard the CG range should be pretty wide, so as long as I get it close and maybe a little nose heavy I should be OK

[aaronredbaron]

I can't see how the image can apply to the quickie, because the front wingspane is nearly the same as the rear it would render to rear wing nearly useless. if you look at the plane from the front it has anahedral (speelled wrong) in the fron and it is at the bottom of the fuse, then the fuse extends upward and the rear wing is at the top of the fuse with dihedral. looking at it, for me, suggests that the reason the plane was designed the way it was, was to eliminate any airflow from the canard interfering with the airflow over the rear wings. I need to get a digital camera.....

[DanSavage]

Originally posted by aaronredbaron
I can't see how the image can apply to the quickie, because the front wingspane is nearly the same as the rear it would render to rear wing nearly useless. if you look at the plane from the front it has anahedral (speelled wrong) in the fron and it is at the bottom of the fuse, then the fuse extends upward and the rear wing is at the top of the fuse with dihedral. looking at it, for me, suggests that the reason the plane was designed the way it was, was to eliminate any airflow from the canard interfering with the airflow over the rear wings. I need to get a digital camera.....

I think you've got it wrong.

Find the canard area (A)
Find the wing area (B)
Find the Neutral Point for the main wing. (NPW)
Calculate the CG for the canard and the main wing at 1/4 chord (25% MAC)
Find the longitudinal separation distance between the two.

Multiply A times longitudinal separation.

Divide A + B by the result.

This gives the distance from the CG of the main wing to the neutral point. (NP)

Next, add the distance between the NPW of the main wing to its CG at 25% MAC to the result of the calculations above to find the starting CG of the model.

The configuration of the Quickie you describe is why I wrote what I did about the wing not flying through the canard's downwash. For the purposes of calculation, I could simply leave the rear wing effective area at 100%.

Dan

[aaronredbaron]

sorry about the confusion... there is only one way at this point to see if it is right!

[Ollie]

The downwash behind a wing extends several chord lengths above and below the wing. That's why some wind tunnels can measure the coefficient of lift by an array of manometers placed in the roof of the windtunnel. That's why biplanes are inherently less efficient than monoplanes and why the greater the gap between the top and bottom wing, the less the wings' efficiency is degraded.

The air flow over the aft wing is slowed by the influence of the forewing and fuselage. In calculating the neutral point, an allowance has to be made for the reduced effectiveness of the aft wing. This is usually done by using a smaller area of the aft wing in the neutral point calculation. It is very hard to accurately estimate the actual reduced effectiveness of the aft wing. To cover this uncertainty, it is best to start out with a static margin of 15 or 20%. That is with the CG 15 or 20% of the wing's mean aerodynamic chord ahead of the neutral point in a tandem wing design.

For a fuller discussion of tandem wing setup see R/C MODEL AIRPLANE DESIGN, Chapter 10 by A.G. (Andy) Lennon. The rules of thumb in Lennon's book have been verified experimentally and would apply well to the Quickie configuration.

[Trizza]

You could always build a small balsa model to figure the CG out with. Just to glide test in your living room or something.

[aaronredbaron]

I feel very confident having the right info. they claim it is a very good flying plane and flies pretty fast...we'll see

[aeropenguin]

Hello guys!
I am very intersted in your Quickie, and I am in the proccess of designing a much, much smaller scale model of the quickie, and needed a few good pics or 3 view diagrams - well, the more views the better.

Do you still have those plans of the full scale Rutan Quickie? Do you know where I could get them or find pics? Or even less acurate drawings with just outlines? Can you scan in your plans?

If not, do you have any directly side view photos or directly top view (as for top, I see a good one on the link you gave in the first post, but it is small and a little hard to understand how/where everything goes/fits) or front or back?

Thank you very much!
-Michael

[daisycutter]

does anyone have a pic?

[Sparky Paul]

Did a search on the 'net for "quickie".... !!!!! Amazing things you can find!!!! :D:D:D:
.
Got results with "quickie & Rutan"...
dimensions -can- be read with a little enlargement..

[aeropenguin]

guys, looks like somebody did ALL the math for ya......

and drew in formers, bulkwalls, fuse sides...an entire plan.

NO, two entire plans!!!!!!

http://www.rcgroups.com/forums/showthread.php?threadid=122436&highlight=quickie

http://victorian.fortunecity.com/stoker/123/

[aeropenguin]

click on planos, then scroll down until you see "Quickie" under the canard section, then scroll down more until you see "Qac-Quickie" they are the two plans, both scale. The Qac-Quickie is harder to build from and much less complete, but it is far more scale. Elevator goes in front wing, aileron goes in the back wing, for three chnnels. For four, add the rudder..... rudder and elevator doesn't work...
-aeroP

P.S. SPARKY, that's noit the Rutan Quickie, I'm sorry to say. That's a dragonfly or something. The way you can tell is that the Q has straight fuselage sides, looking from a top view.

[Sparky Paul]

Originally posted by aeropenguin


P.S. SPARKY, that's noit the Rutan Quickie, I'm sorry to say. That's a dragonfly or something. The way you can tell is that the Q has straight fuselage sides, looking from a top view.
.

magnify the title block.

[Matt Chester]

Its the two place version of the Quickie which is called the Q200.

[aeropenguin]

Hmmm, that's intersting - thanks guys, and sorry Sparky!
So, it has room for two people? One behind the other or side by side?

Thanx!
-Michael

[aaronredbaron]

http://home.globaleyes.net/shoskins/quickiepage.htm

[Bill Mixon]

For those interested in quickie instructions and drawings etc.. There are some templates and CD manuals listed on Ebay. Don't know how good the quality is.

Quickie Plans (http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=2427627108&category=26441)

I've been curious about the flight controls on the full scale Quickie. The elevator control is on the front wing or canard and the rear wing has half span ailerons.
Would a different arragement be better suited for rc flight? Such as elevator on the back with ailerons on the front. Or maybe an elevon (Delta Mix) setup on the rear wing only?
Could even use two or three mixes with 4 control surfaces and 4 servos.
Any of you guys have any thoughts on the above.

I remember reading about some of the full scale Quickies going into an unrecoverable dive due to slightly imperfect wing sections or something as simple as bugs or rain getting on the wing.:eek:
I think this lead to a different airfoil section for the front wing.

Bill

[aeropenguin]

elevators are in the front. Ailos on the back, flaps on the back, rudder on the rudder :) That's exactly how you'd do it for RC too...

[Ollie]

For good stall characteristics, the fore wing must stall before the aft wing. Because aspect ratio determines the induced angle of attack at which a wing stalls, it must be taken into account along with the selection of airfoils

In order that the plane behave well at low pitch attitudes it is imperative that the aft wing go through zero lift before the fore wing. If not, the plane will experience violent pitch down when the fore wing goes through zero lift first.

The stall margin and zero lift margin between the fore and aft wings have to be big enough to withstand variations in the airfoils due to building errors, covering sag, control surface trim offsets, bug splatters, etc. if good handling characteristics are to be preserved. These requirements make the design of successful canard configurations with benign handling qualities a bit more complicated than for conventional configurations.

[Bill Mixon]

Originally posted by Aeropenguin
elevators are in the front. Ailos on the back, flaps on the back, rudder on the rudder That's exactly how you'd do it for RC too... Bugs & rain... whell, whaddya expect with... what is it, ~20 horsepower?

I don't see why the control configuration has to be like the full scale plane. No reason to say well the full scale was built like this so the model must be also. If you used large 30-40% chord surfaces on both wings each with their own servo, you could experiment with all sorts of programable mixes. I don't see why this couldn't be used to change the flight characteristics of each wing in flight at various speeds by reflexing the surfaces, coupling, etc..

What does the horsepower have to do with it? I certainly wouldn't want to or expect to get killed in an airplane by flying through some bugs or rain.:confused:

Bill

[aeropenguin]

Bill, sorry - yes, you are right. I was saying that if you had only elevator, and aileron (rudder does not change anything...) then you would have to use the back wing for ailerons, and the front for elevators. It all has to do with CG - if you placed the elevators right above the CG, then they are not elevators, but rather flaps...because you are directly moving the airplane up&down without much of an "up-facing" angle....

If you place the elevators in front of the CG, then when the elevators go up, you're lifting that area - just the front, therefore causing the plane to "look up"...that's what elevators do on a conventional plane, but instead they are in the back and lower the tail. Lower the tail or lift the nose....same type of effect.

I am almost 100% sure of the above - if I am wrong, please step in and explain.

Intersting facts Ollie - Thanks!

-Michael

[Sparky Paul]

Originally posted by Bill Mixon
...


I don't see why the control configuration has to be like the full scale plane. No reason to say well the full scale was built like this so the model must be also. If you used large 30-40% chord surfaces on both wings each with their own servo, you could experiment with all sorts of programable mixes. ...
Bill
.
There's no "configuration police" ensuring you use what everyone else uses. Do what you want .
Maybe it'll work, maybe it won't. Can't tell 'til you try.

[aeropenguin]

Yes, sparky, but I was just saying that that is what everybody usually uses, and it's what is proven and it works...
If you want to do some complicated mixes and flaps, etc, then I cannot help you out.

Thanks!
-Michael

[Karl B²]

If you expect the nose to rise when canard-mounted elevators move up, it should be a short, but interesting flight. Make sure to get pictures!

[Bill Mixon]

Yes, to pitch the plane up the surfaces on the canard would be in the lowered possition, and up to go down. Not the other way around.

I just might try a 4 servo tandem wing design with programmable mixing and see what I come up with.

Bill

[aeropenguin]

:D :D :D
WOOPS! Yer right - I got that backwards. Doh. Sorry. Obviously the elevators on the forward wing drop down to make the nose go up, thus inducing an "up-looking" plane, and there ya go. Elevator up on the nose wing is like giving a conventional plane down elevator.

-Michael

[HelloMcFly]

I am building a Q-200 in my garage and made a website about it. On my website I have plans for the full size quickie variants that show the CG location.

The CG location for the single seat version is found in a 3-view draing here:

http://www.quickheads.com/Q1-Plans-Chapter-1-Page-1-2.html

The 3-view diagram for the 2-seater version can be found here:

http://www.quickheads.com/Q2-Plans-Chapter-1-Page-1-3.html

As you can see the 2-seater (Q2 or Q200) is more round than the Q1 single seat version, this is because the 2-seaters had premolded fuselage shells. The Q1 was built completely by hand by the homebuilder from sheets of styrofoam.

The Q2 had a "GU" canard airfoil section that was prone to bug and rain contamination causing a loss of lift. This can be corrected either by attaching "vortex generators" or by upgrading to the Q-200's LS1 airfoil section.

You can read more about it at my site. I hope this helps some model builders out there. I started out building models, but I earned my pilot's license and am currently earning my taildragger endorsement. Wish me luck!

Happy building everyone! Keep 'em flying!

Cheers,
Dan Yager
www.quickheads.com

[Thomas B]

On my 1/8 scale 27" span Quickie from Richmodel, the CG is about 1 inch behind the trailing edge of the front wing, at the fuse.

Nice little flyer. Richmodel cloned thier little Quickie from these RCM plans for a 1/2A glow powered Quickie. You might consider these plans as a jumping off point.

http://www.rcmmagazine.com/store/store-plans-catalog-tem.html?item=plans:PL-840&sid=0001RHgbTYZY4zMWBs8Q3K2