coolbean

I can't seem to find it now, but i saw a model here that had no vertical stab per say. The fuse was thin and tall and just kind of flattened out like a half used tube of tuthpaste (You do squeeze from the end and not the middle, don't you?). It was a control line model. I have no expierence with a CL, is there any reason this sort of design wouldn't work for RC?

If you know what model I am speaking of please post a pic in this thread, thanks

hillbillyflyer

i say it should, but there would be no rudder "DOH!" i think you should take a model ( a valuble one preferably) and smash it like tooth paste (smashing from the end not the middle) and chop off the vertical stab and see if it flys

Tall Paul

Control line planes achieve their yaw stability by line tension.
The side area is proportioned to keep yawing to a minimum.
A vertical per se isn't needed.
Some r/c planes can fly without verticals.
ZAGI flying wings for example.
The necessary yaw stability is supplied by the swept back wing tips.
A conventional wing-tail plane CAN fly without a vertical IF the speed is kept up, and there's enough side area behind the c.g.
But this speed is usually quite fast, well above a normal landing speed.
Planes which lose verticals in flight tend to swap and roll over and die.
The photo is of one of my slopers flying without any vertcal, a central vertical, and tip verticals.
The only real flight difference is with no verticals, the plane can fly sideways when slowed in a wind.. the flight direction changes from ahead to along the span. There's no control when this occurs, so the plane falls out of the sky.
With the central or tip verticals, it maintains heading properly.

Bill Teller

I have a picture of one don't know how to get it on the site it's some kind of pylon racing model plane - the top of the cockpit goes straight back & tapers down to a rudder It was at the Danville Va giant scale fli in this fall.
It did not fly while I was there tho.

jetmech05

no no no ok we have a guy in our club that designed and marketed an aircraft with the tail flattened out like a toothpaste tube. its called a PALOMINO. yes its fast but its landing speed is its landing speed for that aircraft. it doesnt have any adverse yaw problems. the reason an aircraft falls out of the sky when side slipped whether it has a vertical or not, is your stalling both wings.
by the way you can get a palomino if you contact awesome rc in garrisonville virginia the club member i mention eariler has one there on consignment
and yes you do need some kind of yaw stability with control line the engine is off set and the rudder is turned out to keep tension on the line. but imagine what would happen with no yaw flying in a wind
planes will swap end for end when you loose a vertical for several reasons. cg shifted fwd you lost all yaw control and yaw stability remember the vertical stab and rudder work together.
as far as winglets go if you have a normal tail, winglets dont offer much yaw stability its a wingtip vortex control device and reduces drag. if you loose your vertical well then winglets is all you have but both winglets surface wont come close to the surface you have with a verical stab and rudder.
if you have no vertical then winglets arent. you have twin verticals mounted at the tips (will also control wing vortex)

blikseme300

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I have seen 2 aircraft in the last 10 years that lost their verticle fin in flight. Needless to say, both needed serious repair. If you have ever played darts, then you will know that if the flight comes off it no longer works, right?

This past weekend I saw my second incident - a H9 Corsair. Once the fin came off it lost all directional control. "Falling leaf" describes what happened next.

Aerodynamically speaking: If you have a rectangular flat plate and the airflow is lengthwise/end-on, then the tendency of the plate would be to turn broadside to the airflow. Long flat fuselages with considerable area have large drag numbers. Area-ruling becomes a big issue with hi speed designs. I am no aerodynamist, but remember some of the theory from college. Fascinating stuff, like voodoo.

Safe Flying!

Tall Paul

I landed this one after a mid-air.. note the chewing on the elevator..
Flying at the lakebed one has the benefit of landing in any direction.. I just let the thing descend slowly on the heading it was already on.

BMatthews

It's all about the side area behind the CG. IF there's enough then it's good, if not then stuff happens like Paul described.

There was a fun fly or sport aerobatic design called the Not For Sale that used this sort of toothpaste tube shaped fuselage and the rear was deep enough to provide the fin effect and a rudder was stuck on the end of that. Model Airplane News sells the plans for it IIRC.

A google for "not for sale" even with other keywords turns up far too many obvious hits so it's hard to find any pics out there. But I think that's the one you're looking for.

Most control line models that use this tail form would be sketchy flyers for RC. I know there has been a few and the precision aerobatic event does require some yaw damping to help the models look smooth but it's far less than a typical RC model needs thanks to the effect of the control lines. You'd likely need to increase the side area a bit depending on how much it's starting with.

cyclops2

Does a German, Horten flying wing of WW II count?
Very stable, without computers.

britbrat

Are you referring to the Gotha Go 229A-0?

beenie

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There have been full scale aircraft to not have a vertical tail. The Gee Bee R1 originally didn't have one. I exhibited some interesting characeristics so a small fin was added. Also, The Beech Starship did not originally have a fin on the fuse, Beech found that the winglets were enough. The FAA didn't like that so a fin was added to the underside of the aft fuse.
Ben

jessiej

As much as I have read about the Gee Bees I hadn't known that, Ben Thanks, and thanks for the photo.

jess

Nashcat

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I knew that I had seen a pic of a not-4-sale in a recent post. I finally found it.


Nashcat

BMatthews

Yes and no. In flying wing with a swept planform the natural drag center is behind the CG. That's basically what you need for any airplane to be stable in yaw. And also with the Horten wings the wing twist provides a further shifting of the drag apparently. Or so I've read somewhere.

This is why Tall Paul's wing in one of the early posts was able to fly without fins. But due to either not enough sweep or not enough twist his wing would become unstable at higher lift coefficients as when flying slowly.

As for very stable, I'm not so sure. It was stable enough to fly yes but perhaps it tended to wander. When Northop was testing their flying wing bombers in the 50's a tendency to wander and oscillate in the yaw axis was one of the key complaints.

kzimmerman

You can achieve yaw control with no verticle stab or rudder. You just have to use clamshells on the outerpart of the wing. that was the yaw control method that northrop used on their flying wing bombers that they experimented with in the 50's. I don't think that it is as good as a verticle stab and rudder, but it does have a very high "cool" factor!

britbrat

The Gotha Go 229A-0 was a twin-engined jet-powered Horten flying wing design, without a vertical stab, & it exhibited notable yaw instability. It only survived three flights, crashing (fatal) when an engine failed & the airframe was uncontrollable with the assymetric thrust of single-engine operation, despite the engines being mounted as close to the "fuselage" as possible (there was essentially no fuselage).

Gremlin Castle

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The B-2 bomber seems to get along without a vf or rudder. Also the Klingberg wings were pretty good flyers.

britbrat

The B2 can't fly without its computerized flight control system -- no manual default because it is too unstable for a human pilot to control.

BMatthews

... and the Klingberg did have issues same as Tall Paul found with the finless version of his wing.

Tall Paul

The loss of directional on a finless wing is cured by adding fins..
On the Klingberg style, a couple of small all-flying verticals near the tips, hinged to rotate as rudders, but with a pin preventing rotation inward, free to rotate outboard works OK.