Hidden Ailerons

[Andy J]

Considering building a DB designef Blackburn Monoplane but from inspection of the plan the wing iappears far too strong in construction to be configured to use wing warping.  Know from talking to others that have built the model along with pilots notes from Old Warden  that  the aircraft  it's a handful to fly. Therefore wondered if an alternative method could be used to hide ailerons on the wing to improve the roll  handling over a conventional  two channel set up for the model.

Pondering if two outboard positioned wing flaps be used in lieu of ailerons whilst keeping the upper surface of the wing solid as per the original appearance of a wing warp design. Can find little discussion on the web if this would actually work although many state flaps are not designed to be ailerons. So would this cocept work?

Alternatively open to suggestions as to how to hide a conventional aileron on the wing.

 

[Denis Watkins]

 

[Jonathan M]

Did the full-size wing warping work in just one direction (down)?  If so then no wonder (along with then other primitive design features) it is a handful to fly!

 

Re the model:  I can't see how one could effectively "hide" any sort of conventional ailerons.  But here are three possible starting points:

1.  Completely re-design the wing for warping as per the full-size; this would require functional bracing to support the delicate structure.
2. Mount the wings in a way that they rotate as a whole but in opposite directions on their main spars via servos in the fuselage (would only need a fraction of movement for effective roll-control).
3.  Stiff transparent plastic trim tabs on the last few inches of each wing, operated by push-pull wires to servo(s) in the fuselage.

The first option would be a major engineering challenge, and would result in a dangerously delicate wing for RC flying.

 

The second option would provide maximum "hiddeness" without the loss of structural strength.  Maybe rigging would still need to be functional (but working in the same direction as the wing-rotation, or slightly elastic?).

 

The third option would be visibly obvious but the easiest to achieve.

[Jonathan M]

PS - The second option above comes from slope aerobatics where 4-Axis is employed for extreme flying (all at the polar opposite of things compared to the Blackburn Monoplane!) but such a system would give you the ability to trim the wing-incidence slightly (in flight using a slider?), still employ rates and differential, etc - until you've tweaked the model for best and safest control.

 

https://www.slopeaerobatics.com/2007/04/13/an-introduction-to-4-axis-flying/

 

 

[J D 8]

If you want an aircraft with ailerons then do not build a Blackburn monoplane. 

However if you want one for the looks then fly the aircraft for what it is, an early type that will have some quirky flight characteristics and only fly in calm conditions.

   Rudder is the primary control on these aircraft types both for yaw and roll. The wing warping can be looked upon as a pilot controlled wing leveling system.

  Although there is little discussion on the Blackburn on the form there are several about the very similar Bleriot XI you may find interesting.

    My Bleriot is flown rudder elevator and I have the rudder operable from both left and right sticks.

[Simon Chaddock]

"Considering building a DB designed Blackburn Monoplane but from inspection of the plan the wing appears far too strong in construction to be configured to use wing warping."

Andy. Are you sure? The DB kit includes the fittings for wing warping if you wish to use it.

 

From what I can determine the warping control functions on the upper and lower bracing wires on the rear spar. The wing section, at least on the original, is so thin that it relies entirely on the rigging so any movement of the wires will cause the wing to twist.

From what I can determine it is a 'balanced' system in that the flying loads on the bracing are not carried by the warping control.

As JD 8 points out wing warping was an integral part of the Blackburn Monoplane. Seems a pity to make a scale one without it.

 

The issue with all wing warping systems is the fact it creates positive washout on the 'rising' wing so actively promoting a stall created from the tip. In the case of the Blackburn it does this on a wing section that is bound to have very sensitive stall characteristics.? 

  

[John Wagg]

What's the chances of steering using separate elevators (tailerons) ?

 

[Outrunner]

Why not stick to the plan as designed? DB knew how to design a good flying and practical model that are straight forward to build and fly.

[Robin Colbourne]

The big problem on these Edwardian aircraft is that they fly so slowly that the adverse yaw can be greater than the roll effect from either wing warping or ailerons.  In addition, Ailerons can act as a servo tab, twisting a wing without much torsional stiffness in the opposite direction.   Shuttleworth Collection pilot and former aeromodeller, Rob Millinship, describes this with respect to the Bleriot XI here:   Rob Millinship - Flying the Bleriot XI

Faced with the same issues as the Edwardian aeroplanes (structures lacking stiffness plus a very low flying speed), early microlights, such as the Eipper Quicksilver, used differential spoilers on the upper surface of the wing.  Raising one spoiler increases drag and reduces lift, causing the wing to drop and the aircraft to yaw in the correct direction.  These can be seen at about 1/3 chord on the outboard parts of the lighter coloured part of the wings here.
 

Edited December 19, 2021 by Robin Colbourne

[GrumpyGnome]

If you do go for wing warping, I'd advise sticking to recommended power so it flies as slowly as intended' allowing the wing warping to actually work.

[Andy J]

Unfortunately wing warping adds a whole lot of complexity to the build so would like to avoid it if at all possible.

 

As an experiment to only using flaps was thinking I could programme a mix into an existing model that only allows the ailerons to travel in one direction which would mimic my concept of a concealed flap on the underside of the wing. Mix would be controlled by a switch to allow comparison of roll and any associated coupled yaw by the lack of a counter balancing aileron drag.

[J D 8]

  What you are describing is a differential aileron set up which is common on many aircraft. Look at pictures of early types like the Bristol Boxkite, and Farman types  and  while on the ground and you will see the ailerons hanging down and were only held up when flying by the airflow. As noted more a wing leveling system not a roll control. Primary roll/yaw was still the rudder.

          In the early 80's I had a microlite very like the quicksilver Robin pictures above with wing spoilers but rudder was still the primary control.

[PatMc]

Adverse yaw with wing warping was recognised by the Wright Bros before their first powered flight. Flyer 1 had coupled rudder/WW as a result.

 

Andy, Boddo's designs are usually overengineered & the scale ones "practicalised" true scale integrity was never a priority.

IMO the choice is : 

a) put up with an handling shortcomings with no WW,

b) WW with coupled rudder,

c) modified wing with discreet built in ailerons with differential & coupled rudder.

OTOH you could go the whole hog & redesign the wing to truer scale (but less robust) and fly the model accordingly albeit only in limited wind conditions.    

[eflightray]

My Blackburn 1912 Monoplane (RM 140 plans (UK Radio Modeler or - Sarik Hobbies MAG1523 plans)

Built and flown  long long time ago, used just rudder, elevator and throttle, plus brushed motor, Olympus belt drive, 11" x 7" prop, and brushed motor and Nicad (probably 6 cells), flew great using rudder, looked very realistic.

 

But, if you are looking for an aerobatic speed machine .........

 

Ray.