Race-worthy V-tail quad frame?

[pelotron]

Hello all,

I've been flying RC for a few years, and FPV for about a year on a Windestal Tricopter V3, and have recently joined a local FPV racing group. Obviously I need to build a race-worthy craft, but I think all the run of the mill quad frames are boring looking. I considered a Baby Tricopter, but that would be my 3rd tricopter build so I want to do something different... what about a v-tail?

A v-tail would be awesome and I've been searching around the past few days trying to find a frame, but I can not believe that I'm not turning up anything besides the Lynxmotion Mini Hunter (283 size) and the Armattan Mini V-tail (258 size). Those are good looking frames for sure, but they still seem to be a touch too big. The Armattan comes close, but the website says 7" props are ideal and my racing group limits aircraft to 6" props.

Are there really no other v-tails out there for sale that are closer to around 200 size? I've seen the Eachine but I only want a frame kit. I've only ever been slow flying so something very durable is definitely a requirement as I learn to race (which rules out the FT v-tail).

If anyone knows of a good race-worthy v-tail frame kit, please help!

 

[Darkback2]

Any reason why you want a v-tail over an X quad or H-racer? What advantages do you see in a V-tail that you don't think you will find in a traditional quad?

I'm asking because flat frames look to be pretty standard and you may find that you have to roll your own if you are looking for something different.

:-(

 

[pelotron]

I'd prefer a v-tail simply for the novelty of it; they just look awesome. And the one technical advantage would be higher yaw authority. A disadvantage would be speed due to the tail inefficiency, but from what I've seen I think pilot skill and flying consistency has a much larger affect on race outcomes than raw speed.

 

[Ocean]

I would definitely opt for a quad over a v-tail. The funkiness of a v - tail will wear out after about a week and you will be left with something that isn't as fast as a quad and has odd flight characteristics. Motors these days are so powerful that yaw rate is not an issue. You can yaw as fast as you desire with no issues on a quad.

If your heart is set on a v tail then look at the shendrones fast forward.

 

[C0d3M0nk3y]

Are there really no other v-tails out there for sale that are closer to around 200 size? I've seen the Eachine but I only want a frame kit.

I haven't tried any of them, but I know Horus sells 3 v-tail kits.

 

[PsyBorg]

The Versa copter frame can be easily configured to a Vtail and is smaller then the ones the OP mentioned. I saw a video or two were someone made a Vtail with the Versa frame. Here is one of them.

 

[Habakkukk]

Shendrones has the Fast Forward, it's kinda of a v tail/weird hybrid thing. Definitely unique.

 

[Darkback2]

Pelotron...

I say get what you want. Really that is the only way you will be happy. V-tails do look pretty cool, and they aren't run of the mill by any stretch of the imagination. The shendrones FF looks pretty cool, I do think you will have some odd flight characteristics to deal with, but I also think the challenge will be well worth your while. In the least you will learn a ton.

I am curious about the size of most commercial v-tails. They seem to all be larger than the more traditional race quads...I am wondering if anyone knows why that might be?

Best of luck to you, and please keep us posted!

DB

 

[pelotron]

Thanks for the suggestions guys. For better or worse my heart is set on a v-tail. I think the Horus Harpy might clinch the title, though I didn't realize that the VersaCopter could be made into a v-tail.

The FastForward is very interesting... I will keep my eye on that frame and might be tempted by it some day!

DB - agreed, I don't know why almost all v-tails are so big. Nothing wrong with big copters - my two have run 9" - 11" props - but I would think v-tail makers would want to offer something for the race crowd as well.

 

[Darkback2]

Maybe you want to roll your own? Seems like someone could design something smaller and better than what is out there. The hard part would be making the frame. If you were willing to go with fiberglass instead of carbon fiber you could probably do it at home, and if you were dead set on carbon fiber I see a few options...Buy some pre-preg and do it at home, Send it out to have it made...or cut down an existing frame and use aluminum or 3d printed brackets.

In either case go with what you can for now. you can always change things up later.

Best of luck!

DB

 

[Craftydan]

The reason you see V-tails in the larger sizes and not the smaller, effectively, is geometry -- the whole point of the V-tail is to emulate the tricopter thrust vectoring using two motors instead of one motor and a tilt. While tri's take on their own odd flight characteristics -- mostly in control coupling, but some other odd behaviors -- V-tails tend to be better behaved the closer the tail booms are to each other. Bring the motors reasonably close to each other and they take on a few of the tri's characteristics, while flying a bit less coupled than a tri -- Like a Tri, only better.

This starts to fall apart a bit as you get smaller in scale -- where a 500 class quad can move the front rotors way out on booms and plop the tail motors a fraction of that width apart from each other, you simply don't have the space to pull that same stunt on a 250, 200, 180 class quad . . . in many cases, all four motors are already near their neighbors . . . so you're left with an illtempered airframe.

Cool counts for a lot -- make no mistakes about it -- but most pilots want to win the race or freestyle *while* their airframe looks cool. If the typical pilot is going to give up something for that cool, performance generally isn't it. Keep in mind, most race leagues -- even some of the better ones -- are still decided by a DNF more than shortest time. The hotshot (and let's admit it, cool) pilot who was burning everyone through the gates clips the second to last gate and goes for a tumble, even if he can recover, won't be winning that heat.

So beyond cool, what does a V-tail give you? Stronger yaw, for the cost of some odd control coupling. Not a particularly favorable trade. I hate to say it, make sure your Thrust:Weight above 2 and a 250 class quad (or smaller) will have more yaw than most pilots will ever want . . . not to mention I don't know of a competitive racecraft with less than 2:1 -- it's a bit on the anemic side.

All that said . . . I am a big fan of V-tails. I do like how they fly, they're cool to watch and fun to feel, but I'm not inclined to pick up an FPV racer in the style. Traditional quads fly flat in comparison, but if you're racing through trees, pulling stunts or zipping around a course, predictable substance wins over clearly good style.

This is not to encourage you to do anything other than what you want to do, but instead to answer the "why" a vast majority of the market goes flat, and the nitch V-tails remain a nitch. Your build, your call.

 

[CrashRecovery]

MultiRC has a 130 sized one
http://multirc.com/winzig/

 

[pelotron]

...Bring the motors reasonably close to each other and they take on a few of the tri's characteristics, while flying a bit less coupled than a tri -- Like a Tri, only better.

This starts to fall apart a bit as you get smaller in scale...

I hadn't thought about it from this point of view. You're appealing to the engineer in me now. I'm starting to feel obliged to go through with it and report back.

This discussion is reminding me a little of what goes on in bike racing circles. I used to race in amateur races for a couple years (cat 4/5) and even at the "entry" level you saw mostly carbon fiber bikes and other really high end gear. But at the end of the day your average amateur racer will never reach a level of performance where that equipment makes a difference. You can save a few pounds buying a carbon bike over a steel one, or you could just train harder and lose a few pounds of fat off your body. I feel like I'm at that point getting into flying fast FPV - my skills will have quite a ways to go before I bump against the performance limits of my aircraft.

And when I do hit that limit, I have no problem planning another build.