"Vulcan-A": A prop in slot KF jet - PLANS

by RustyMustard | January 22, 2014 | (0) Posted in How To

Hi folks!   Last time I brought you the Gloria Trainer, a mellow, slow, easy to fly bushplane style primary trainer.   This time I have something comepletely different for your micro flying pleasure.

 

Introducing the Vulcan A!

 

It uses an AR6410NBL brick, 2s 300mah battery, UMX Beast motor, an two linear servos, just as the Gloria Trainer does.

 

This has to be one of the easiest things you'll ever build, with 5 pieces of 3 shapes of foam, some pallet strap, hot glue, tape, and a CF rod for a motor mount you can be tearing up the sky with this Avro Vulcan bomber inspired prop in slot delta wing.   I'm also going to introduce you to the technique of using pallet strapping to create a rigid structure in a foam airframe.   To learn more about this technique, see this post at RcGroups.com.

http://www.rcgroups.com/forums/showthread.php?t=2047264

Here's the plan:The Vulcan A

The first thing you want to do is print out the plans and cut the three shapes you need into templates.   I like to use posterboard, that way i can simply trace it out on a dollar store foam sheet and make replacement airframes in no time.  Now, trace out one wing, two KF steps, and two tailfins in the foam and cut.   Score cut the elevons on what will be the bottom of the wing and do a 45 degree bevel in the wing side.  Strip all the paper from the foam, separating the elevons, and reattach each one with clear packing tape.   You should have a single plate wing with elevons now. 

 

On to the next phase of the build, the construction of the A-frame using the pallet strapping reinforcement technique mentioned previously.   The concept is simple, on each side of the foam, pallet straps will be glued onto the foam following the lines on the plan so that the foam is sandwiched in between the straps.   It is essential that the straps on either side be lined up with each other, or all the benefit of the added strength will be lost.   On mine i use hot glue, but others have had success with other types of glues.   Feel free to experiement with you favorite glues and see what you like.  I tack one end of the pallet strap along a mark, and a few inches at a time, lay down glue and press the pallet strap tight, squishing out the glue and squeegeeing it off.

Following the plan, your foam wing with A-frame pallet strap structure should look like this:

Bottom:

 

And the top, with KF step lines drawn:

 

If your A-frame looks like this and your wing is stiff, you're ready to glue the KF step on.

 

 

Note the gap in between the two KF steps.   Make sure its wide enough to fit your CF rod for the motor mount in it.   Cover it with packing tape, at least on the leading edges and around the prop slot.   I did a simple yellow and black scheme on top, along with leaving some background bare foam.   On the bottom i did solid black.

 

 

After you're all taped up, install the fins using the angle of the trailing edge of the fin as a jig.   It helps to slightly sand a bevel into the fin so it sits flush at the proper angle and makes a good glue joint.   From here on out, it's a matter of installing the electronics and rigging the pushrods.   Take your CF rod that will be your motor mount and glue it from the nose LE between the steps, all the way back to the prop slot.   Leave the last 1" free of glue so you can mount your motor.   The rest of the radio gear is simply hot glued in place as shown in the pictures above.   A hole for the battery wire and two slits just behind the KF step on either side of the CF rod are cut, and velcro strap threaded through the slits.   All there is left to do is make some pushrods of the proper length, a couple of control horns from small zipties, and you should be ready to tear up the skies, Vulcan A style!

For more detailed information, pictures, and build discussion, visit the Vulcan A thread over at RcGroups.com.

http://www.rcgroups.com/forums/showthread.php?t=2057661

 

Flying the Vulcan A:

Start by checking the CG, it should be just in front of the prop slot, at 4 5/8" back from the nose.   With control surfaces at neutral, adjust the battery placement for a good glide as a starting point.   This should keep the nose up on launch, and will need to be flight trimmed with a bit of down to attain level flight at half to full throttle.   Once you know how much down trim you need, adjust your linkages accordingly and reset the TX trims to center.  For the maiden, use 70% rate with 40% expo and when you're really ready to rock, go full aileron rate.

This thing should fly like it's on rails, go exactly where you point it, and have no power/pitch coupling   If it doesn't your CG and trim is off.   Rolls should be fast and perfectly axial.   If it barrel rolls, you need more down trim, if it rolls slow it needs a bit of up.  The inward canted tailfins give it a wild roll rate when it's all dialed.   Inverted flight requires only minimal back pressure.   Play with the CG and trim, when you get it exactly right, it'll fly like a dream.

Did i mention it's crashproof too?   Fly it like you stole it, the CF rod, A frame, and flat nosed delta shape make it indestructable.   You might break a fin or an elevon once in a while, but those are easy fixes.   They'd be great in combat, and a slick pilot could whip one around indoors at full tilt, it's fast for it's size, but it's insanely maneuverable.Hoe 

COMMENTS

Royall on February 1, 2014
cool plane! Just curious... what town is that?
Log In to reply
Turbochanger on February 1, 2014
Nice design. I wonder how the flight envelope would change if you put a nose on it, more like the original Avro Vulcan
Log In to reply
RustyMustard on February 1, 2014
I haven't tried it, but i imagine not much as long as you keep the CG right. I'm thinking it might roll a bit better, but rolls aren't a problem to begin with, they're already fast and right down the centerline. I did try using a single tail on the prototype, but the twin canted fins gave the best roll rate and stability combined. Gyroscopic effect of the motor being almost at the CG, the propwash through the fins giving a ducted thrust effect keeping the inboard ailerons in clean air (this also eliminates any power/pitch coupling), and the low pressure zone of accelerated air between the fins all add up. Another thing is the tapered ailerons. It should be trimmed to need a slight bit of down trim to fly best, for agility, drill bit rolls, and so that the aileron's taper adds effective washout to the tips.

All this and a few other design features like the top KF step give this little thing a locked in feel like a bigger plane. I did a lot of work on this thing to get it to fly with surgical precision.

Check the thread on RcGroups.com, Pardshaw built two sized up to 29" that fly well on Blue Wonder motors by his flight reports.
Log In to reply

You need to log-in to comment on articles.


"Vulcan-A": A prop in slot KF jet - PLANS