BMFA In the Air Tonight - 25/04/2023 @ 7pm - 'In the Air Tonight' - Operating in the Outer Hebrides and the 'Breezy Flyer' with Andy Twort

An excellent session tonight, very many thanks Andy

Following on from last night's talk, I'm posting here to list the main design features of the Breezy Flyer.

Please feel free to comment and ask questions. - Andy

Nose down wing (approx. 7 deg) this is so that the lift is negative when sitting on it's wheels. - The stronger the wind, the more that the model is forced on the ground. Traditional taildraggers with their nose high ground attitude are very prone to lifting off  and inverting on windy days. - This feature is the main design characteristic of the design.

Wheels on the wingtips. By placing the wheels at the extremities, the wingtips cannot rise irrespective of how undulating the surface of the flying site. With conventional gear spacing, any undulations will cause the tip to lift. in a crosswind situation, this could lead to the wing acting like a flat plate and blow the model over. Also this configuration allows the wing to be kept within a couple of inches of the ground, where the windspeed is at it's lowest.

Very simple Fuselage. - At some point, there is a fair probability of a bad landing. - The simple fuselage is easy to repair or replace. A model that is very quick to build allows a flyer to operate in challenging conditions without the worry of writing off a model that has taken hundreds of hours to construct.

Controls - These are large and powerful, in gusty conditions, having powerful controls is very useful to get the model back on an even keel when disturbed by turbulence. - Exponential helps with reducing pilot induced oscillations. Having the surfaces shorter than the wing / tail protects them in the event of a cartwheel.

Rubber Bands. the fuselage to wing joint uses rubber bands. This gives flexibility if arriving at the ground in an "unusual attitude"! Hopefully reducing damage. It also allows very quick disassembly in the car after flying. The model was designed to be transported fully assembled in the back of my VW Golf. 

Linkages on top surfaces Obviously this stops the horns from ploughing furrows in the runway.

Motor. - This is as low as possible, though this is still pretty high - with a fairly high tail ( the fuselage rises up at the back to allow for rotation) the propwash acts on the tailfeathers. The motor is powerful to get the model away from the ground quickly

Top Battery hatch. - Whilst I really enjoy flying my Riot, Having to invert the model on a strong wind day to install the battery is an extra challenge. Being able to place the model on the ground (into wind) and simply connecting the battery before checks and take off makes  operating a lot easier.

High Drag. - nobody enjoys having high levels of drag but I considered that the fuselage simplicity was worth the extra drag. The motor can cope with the drag and whilst this reduces flight times on a battery ( I use a 3S 2200) it's for operating on windy Hebridean days where short flights are the preferred mode of operating.

High moment of Inertia. All the mass is at the extremities - Motor at the front, - tail group servos at the back, wheels at the tips. The idea is that this high moment of inertia will help to reduce the impact of the gusts. - In reality, it probably has absolutely no effect at all!

Strong wing and tail group.  Following on from tales of snapped wings during ground handling on windy day, I made the spar from spruce and ply. The tailplane and fin are re-inforced using aluminium carbon composite arrows.

I actually found this episode the best of the lot . A member who is prepared to get stuck in and who used his imagination and alternative parts and was prpared to experiment . All characteristics of a true aeromadeler , my opinion ! A plane built for a purpose ! not sure about the tip wheels?  but it works !!

Arrow shafts !! Used them for years as spars and push rods on the bigger planes , why ?? cos the next village had a bow and arrow shop , very rare  , and there was a scrap bin of not quite .001" true shafts  , used to be 85p. How about taking the polystyrene from your new TV box and making it fly !!?? as a club we did that, hilarious , and they all flew     eventually !  there are lots of ideas about that dont get an airing  and some of them might actually be useful.

cheers

Pete, thanks for the nice comments.

One really great thing about playing with designs like this is that there really are no correct answers. The undercarriage is an obvious example - possible other solutions include a monowheel with tip (or midspan) supports, like the RF5 or Europa. Another solution could be a belly skid or pair of skids and with strong winds and lots of power, it would probably slide itself into the air. You could decide that getting the model really close to the ground is not important and put a "standard" tricycle undercarriage under the plane.  There are lots of possible solutions and of course one can experiment with all of them and decide which solution is preferred.

For me, experimenting with different ideas is great fun, though not all ideas are necessarily totally successful!!!

Andy