Hello! I am a new contributor to the articles section and pretty new to the hobby. I joined the Flite Test forum in late 2018 as a complete beginner to flying and building RC planes, wanting from the very beginning to design my own planes, with no experience in aerodynamics at all, RC or otherwise. I got off to a rough start, but thanks to the wonderful community here at Flite Test and all the help and encouragement I received, I pulled through. I have not only learned to build and fly, but I've actually gotten a couple of my own designs airborne and flying pretty well.
The V-Sliver is a design based on a concept that I have wanted to explore since the very beginning of starting the hobby, and I want to share my experiences with it, my reasons for building it, and some information about slender delta planes and why they are awesome. This is not a build tutorial, although I may eventually publish some plans, with help from members of the community. I encourage all the mad scratch builders out there to do their own version of the slender delta theme!
Slender Deltas; The Science
How does a classic dart paper plane fly so well with such a long skinny wing without needing to go mach two to maintain lift? Vortex lift, an aerodynamic effect inherent to delta wings where the air flow along the sweep of the wing creates turbulence in the form of twin vortical wakes, adding lift. The effect increases at high angles of attack.
During studies that eventually lead to the development of the Concorde, it was found that increasing the length and sweep of the wing increased the phenominon of vortex lift as well as suggested a wing with very low aspect and drag that would work well at supersonic speeds, and was hoped, would handle well at lower speeds too. To test this "slender delta" theory, the Handley Page 115 research aircraft was built. It has the distinction of being the most acute delta flown, but had a top speed of well under 300 mph for low speed research, and was noted by test pilots(Including Neil Armstrong!) to be quite a docile and smooth handling plane. The HP-115 and slender delta theory formed the main basis of inspiration for my V-Sliver design.
Slender Delta RC Planes
How does all that work as an RC plane, and why build one? For me, a big part was aesthetics. I love the retro-futuristic, looks-like-its-going-supersonic-while-sitting-still, space-ship like look of slender delta planes. I also love the way they handle, the unmatched slow high alpha, the graceful pitch and wild roll.The science of vortex lift is also a neat topic that adds some novelty and mystique to the idea. I will sum up as best I can the pro's and con's of a slender delta RC plane.
Pro's: Unique and distinctive profile, unique handling characteristics, *(edited due to new findings. A simple wing loading calculator was very revealing) surprisingly LOW wing loading when keeping fuselage proportions modest, outstanding(perhaps even unmatched) high alpha capability, gentle pitch, good high speed flying, outstanding low speed performance and handling especially at high AOA, ability to maneuver in confined spaces(good option for flying in a gym or small outdoor space), HUGE ground effect that makes landing very forgiving and easier than any conventional plane, barrel rolls for days(if using a standard elevon setup), great portability(toss it in the back seat without having to disassemble the wing).
Con's: touchy roll axis that will need expo, wing rock(Dutch Roll) amplified at higher speeds and by any dihedrals(such as on an RET setup like the V-Sliver).
My Design, the V-Sliver(With Flight Videos!)
My V-sliver is a more beginner friendly twist on the slender delta theme. What sets it apart from most other slender and other types of delta is RET(Rudder, Elevator, Throttle) control shceme that is most often found on trainer type planes, as opposed to elevons, which are most often employed on deltas. My reasoning for this design element is to eliminate the need for extreme build precision that elevons require, and to tone down the touchy roll bias somewhat.
The V-Sliver with its RET setup and dihedral wingtips loses the ability to do proper barrel rolls like an elevon plane, but is more forgiving to build and fly. I wanted something as simple to slap together as a Nutball and at least as easy to fly(easier in my personal experience!) It retains all the other handling qualities of a slender delta plane, including the extreme high alpha capability.
The high-mounted pusher configuration (thanks @Dr. Looping Looie for the inspiration and bouncing ideas back and forth!) adds a bit of nose-down tendency(Deny the dip!) that will need a bit of trim and awareness, but it keeps the prop protected and the area and structural integrity of the wing intact better than a slot prop. This is not a build guide, so I will not include all the specifications and parts(that's for the build thread and possible plan release). My build is in the "mighty mini" size range, but I'm sure the concept will scale up nicely. The time stamp on the following videos is off,and should read 2019,as I only began flying successfully and recording footage in March and April 2019.
Here's a vid of me getting used to manipulating the throttle and working at different speeds and angles of attack:
Here's a vid that showcases my best landing to date, and the high alpha and ground effect qualities of my design:
This is my first article, and I'm very far from a pro at building and flying, and even less experienced at uploading and editing video footage, but I hope sharing my experiences will spread the word about slender delta planes and get more RC flight enthusiasts and aerodynamics nerds interested in them. I also hope this will inspire others interested in developing their own designs to step up to the challenge! This was a hard process for me, and required a lot more thinking than a kit build or somebody else's design off of a plan, but scratch designing is not rocket science!
The V-Sliver is not the most comlicated plane, but a slender delta is a stretch from the basic trainer style home designs most people start experiementing with, and I was still able to develop it after less than a year of cutting my teeth as a complete beginner to every aspect of the hobby; flying, building, designing, and general aerodynamics. I did it with a pencil, ruler, and graph paper, without the use of rendering programs. If there's any fellow hobbyists out there more experienced than myself who are still hesitant about trying their own designs, my advice is to give it a go, you'll be surprised at how quickly you'll exceed your own expectations!