I took another shot at designing a fixed wing. I don't have any serious plans with it yet. Just a design experiment like my last one wich turned out to be all looks and no efficiency. This one is a flying wing design. And again, I have no clue and need some expert advice. As of now it has a 2.5 meter wingspan run by a 13" pusher prop. I think that may be too small? The cutout for the motor is 40mm, I thought that may cover all the size motors that it could run on. It has an internal front mounted tilt camera similar to my quad design. The slit in the front allows a 17° tilt up and 90° tilt down. I posted lots of pics because it's kinda hard to perceive its form due to its streamlined shape. But don't let the shape fool you, it has a payload bay thats 10cm at its deepest point, 20cm wide and 45 cm long.
Looks Awesome I have O experience with flying wings other than I know the COG has to be close to right on and it is nearly impossible to change the angle of incidence The way you check in an RC plane You take it up high and let it free fall straight down with the controls neutral If the nose pitches up The incidence is to high if it pitches down the incidence is to low if it flies straight down it is right on . The incidence is usually set in a flying wing at the factory .When you are scratch building the incidence is a crap shoot? On a normal plane you can usually tilt the wing to adjust it on a flying wing you might be able to do something as long as you don't get to far from the COG by moving weight for and aft Good Job designing though.There is probably people out there that know . Have a good Day!
Now we need Chris Anderson to come up with a clever machine that can rapid prototype these mid to larger size curvy designs without requiring 100's of hours of manual work to get them from computer to flying field.
Great looking plane
If the prop is the right size at 13 inch then the span is wrong at 1,5 meters (should be about 1/4 of the wing. or did I miss something.
the design and sweep look Ok but controls are too narrow and the winglets are the wrong angle to the center line. they need to "toe in" 5-10 degress to provide yaw stability. Use a calculator to find the correct CG and go 5 % forward for the first flights. Add reflex to the control surfaces for the first flights and reduce it as you go but do not eliminate it completely or it will bite big time. I love flying wings and I'd like to see the results later.
@Carl: Thats pretty much what I've heard. Thanks for your commets.
@Curt: Indeed! Preferably a StarTrek inspired materializer or something :-) But I'd be satisfied with anything that cuts time+cost and gets the job done.
@Dwgsparky: You're correct about the prop, I calculated and a 15" prop is correct for the size. Any idea what range of motors are doable? And you are correct about the control surface as well, I've already corrected that. What you are saying about the winglets is totally new to me. I thought they had to be parallel to the center line.
What do any of you think about adding some dihedral?
This is all valuable information, thanks a million...
The mistake people make with flying wings is that they expect them to fly like a normal plane. The truth is that a flying wing needs a certain amount of drag to work , the trick is to get the correct amount of drag either by reflexing the controls surface slightly and /or adding winglets. For the winglets to do something useful other than sit in the breeze you can fit them with 5' toe in so that if the wing is moving correctly and parallel to the centreline than both winglets show the same amount of drag and the plane flies straight,
If the plane yaws to the left then the right tip will produce more drag and the left tip will produce less drag pulling the plane back to a neutral condition . Think of it in the same way that dihedral keeps a plane level. if the left wing drops then the lift are becomes greater than the right wing and so it lifts the left wing back to a stable position.
Flying wings are very efficient (low drag) and you will not need as much power as you expect, typically 50% of the power of a high wing trainer of the same weight will fly a wing as fast and smoothly as you want.
Remember that a flying wing section is different to a "normal wing"
Diherall is not good on a flying wing, I build mine flat on top but with the bottom having a slight dihedrall from the difference in root and tip thicknesses.
Once the flying wing bug bites you will never build a normal plane again.
Great insight. It's echoing what I've been reading up on.
"For the winglets to do something useful other than sit in the breeze you can fit them with 5' toe in so that if the wing is moving correctly and parallel to the centreline than both winglets show the same amount of drag and the plane flies straight"
I've added a 7.2° toe in. There's actually some math to that based on some other factors. I found a good writeup here: http://j.mp/JHtMPk
"Diherall is not good on a flying wing, I build mine flat on top but with the bottom having a slight dihedrall from the difference in root and tip thicknesses."
I started researching winglets based on your first comment and I've found this to be correct. Winglets actually have a similar affect as a dihedral wing shape. But I think I may try the flat top.
Thanks so much, this has been very valuable. I'll post the updates in a few days :-)
Eric, 12-13" prop is correct size for 1,5 meter wing...Or you want to flew with 600W power?
CORRECTION! I apologize for the mistake. The model is 2.5 meters without winglets in my CAD software. So my question is is still open :-/
Thats a beauty Vladimir. Does it have any dihedral? Thanks for the specs!
You welcome. :)
But...You go wrong way.
Every tailess design nice flew with hand and dramatically hard to tune with autopilot. Especially with pusher prop. After few years of experiments I completle lost interes for tailess design.
Yeah I know I picked a challenge. Lots of science involved, but I'm willing to do the work. It's not really an official project yet, just a CAD dream. I have a quadrotor project that consumes most of my free time. But if I take this one on, I will go the distance with it. Maybe prototype in a smaller foam version like the x8 or something.
I should be able to get to poland from berlin and back with a 10,000 mah lipo. Hehe :-P