Swanlander's blog View Details
Posted by Swanlander | Mar 20, 2021 @ 09:00 AM | 11,410 Views
Here are some detail views of the lightweight EDF Vulcan.
The nose slides on, two alloy tubes engage on rolled paper tubes. Three pairs of magnets hold it in place.
The lower surface of the aeroplane is a bit light on detail, the absence of landing gear doors detracts from the scale effect, so it seemed daft to try too hard here!
The decals were designed on commercially available presentation software, using a combination of custom artwork and photos from 'tinterweb. They were printed on water-slide paper using an ink-jet printer.
The matt acrylic white is brush-painted , but is not an exact match with the decals, so the edges of these transfers are visible. Any suggestions for getting this right next time will be gratefully received!...Continue Reading
Posted by Swanlander | Mar 18, 2021 @ 05:27 PM | 13,999 Views
A lovely calm day yesterday, with lock-down rules easing.
This allowed me to venture out to give the new Vulcan it's maiden flight.
Flew straight off the board with CG very slightly too far aft for comfort. Video footage failed. (Stupid phone flipped to look the other way!)

Has to go back today to repeat the footage, though the wind was more noticeable and the cloud cover was heavier.
Battery was placed 2cm further forward and model behaved well.

Lockdown_Vulcan (1 min 47 sec)

Posted by Swanlander | Mar 13, 2021 @ 01:36 PM | 7,682 Views
I now understand what artists mean, when they say that the trick is knowing when to stop.

My wife has helped with colour mixing for the fin root antenna, as I am red/green colour blind...

I won't carry on with adding any more details now, 'twould be like putting lipstick on a pig.

Now I need to make sure I can wait for dead calm for the first flights, which will be outdoors!

Here's to a bit of freedom from lock-down very soon.
Posted by Swanlander | Feb 20, 2021 @ 05:37 PM | 6,239 Views
When making a really lightweight indoor model, the physics of flight loads becomes the guiding design factor. Any considerations of human handling limitations are put to one side, as they would just make the aeroplane too heavy. This is clear to see when looking at duration indoor models in flight, which distort visibly, propeller bending to take the strain as the lift and drag are balanced. Any additional mass will make the aircraft noncompetitive, so the modeller will move in a mindful slow motion as they carefully extract their model from the carry box.

This pre-amble is just to put into perspective my current challenge of building a relatively large indoor scale model. The bigger an aeroplane is, the more fragile it becomes from a handling perspective, hence the title of this blog entry. The skin of this 38 inch span Vulcan is made from Vector Board, between 0.5 and 1mm thick, which, while very light and OK at resisting shear loads and tension, fails miserably in bending. The internal supporting structure is made from Depron, which is stiffer but is quite brittle. With the help of a few judiciously placed strips of balsa to reinforce highly loaded features (ie: spar caps) all this hangs together adequately for cruising round in a nice calm gymnasium.

My challenge now is to find a way to transport the model without it disintegrating in a light breeze between car and hall.

The box I need to make will have to be small enough to fit through the loft hatch from my attic workshop, but will be just big enough to contain the model. That makes it 1000 x 660 x 220mm It must also be light enough to lift above my head. Starting with a simple 3mm thick plywood sheet box design, with an internal frame of pine 15mm square section strip, I realised shortly after cutting the first panels, that this would be just too heavy....so back to the drawing board.

The next stage is to report back when I have a workable design!
Posted by Swanlander | Feb 11, 2021 @ 04:35 PM | 9,267 Views
Now that the basic airframe is complete, I would normally succumb to temptation and fly the thing as soon as possible! With Covid lockdown 3 still very much in place, this is out of the question, so I shall look at the thorny issues of painting and marking next.

Anti-flash white will be the lightest finish, as the base aircraft is predominantly white anyway. (some non-white parts have been painted already) I want to try airbrushing acrylic thinned 50%, (I gather that the ideal consistency for spraying is similar to skimmed milk)
There are many useful pictures on line of our local Vulcan here in Manchester, (XM603 at the Avro Museum, Woodford) so I intend to finish the model with those markings.

The picture below shows the 3 models in this evolution:

Camouflaged XM607, my first Vulcan is now twin EDF powered, with bifurcated jetpipes. It weighs 600g and flies beautifully at the field and on the slope.

The white model in the background has flown indoors and out, twin pusher propellers are powered by 5g brushless motors in the outboard nacelles. The intakes are just crudely marked on with black paint, so the wing does not have the aerodynamic embarrassment of holes in the leading edges. This model weighs 280g and can take off using a removable "dolly" undercarriage. The propellers strike the ground on take off if I am ham-fisted with the up elevator!

The new model is shown in the middle here, waiting to be finished, currently weighing 230g with flight battery. It is not intended to be completed to a competition standard, so will not have any panel lines, pitot probes, aerials etc! I might manage control surface outlines and waterslide markings.
Posted by Swanlander | Feb 07, 2021 @ 06:36 AM | 7,178 Views
Time for some catch-up photos as lock-down two continues, I am now into the fourth month of this project. (Funny how things always take longer than planned, but hey, I am enjoying myself!

Wings are now skinned, albeit with some dodgy joints in evidence. I am currently using copious amounts of lightweight filler to hide these blemishes. Rx fixed in a location which should allow plenty of battery location choice, depending on CG needs. Nose now needs to be located accurately and retained with tiny magnets. Has to be removable to get the 'plane in a custom box which will fit through the loft hatch, or it will never get out of the workshop.

Struggles with tiny connectors have concluded now that bigger 3 pin connectors are used.

Tried to fill in the main undercarriage frames with VB sheet to look like the real outline around the doors, but one leg mechanism touched this new edge and stalled the servo. Before I knew it, the air was filled with that unhappy smell of fried electrics. Bu993er it! One servo down, order another from micronradiocontrol pronto!

Mass target was looking good until I started thinking about painting the beast.
Posted by Swanlander | Dec 26, 2020 @ 11:30 AM | 16,152 Views
Well, after building 2 Vulcans to my own design templates (1/32 scale), one for outdoors and one lightweight indoors, it is time to embark on the bigger challenge of an indoor EDF powered Vulcan with retractable undercarriage.

Unlike the first Vulcan, which now weighs 600g and flies off slope as PSS or flat field power, this one will be made using Vector board for the skin parts, which is lighter than Depron. I am still using Depron for the framework as it needs the stiffness which Vector board lacks.
My target AUW is 250g. This is challenging as my first indoor example weighs 275g which has twin BL propeller drive but no retracting gear.

The new model uses Eflite UMX A10 EDFs, which is driving me to use the Rx from that model too as it has the twin ESCs on the Rx board.
There are two problems with that: Firstly the XPORT mode is locked, so CH5 and CH6 are not available. (need one CH for retracts)

Vulcan_Undercarriage (0 min 10 sec)


Secondly, this mode lock does not allow me to assign elevon mode correctly to the two wing servos. This is doin' my head in, so if anyone has worked out how to wrangle the correct servo sense for elevator and aileron controls in this set-up and explain it to me, I will be forever in your debt.

One alternative is to ditch the A10 Rx and get a pair of external ESCs rigged up to a standard AR6400 board. They will have to be able to cope with some higher current, as the six mosfets needed dominate the A10 board.

Another answer is to actually carry 2 Rx on board, the A10 unit just copes with twin speed control, the other does flight controls and U/C.

All good fun anyway, keeps me busy in lock-down.

Cheers

Vulcan_First_Flights (1 min 58 sec)

Posted by Swanlander | Feb 01, 2016 @ 06:36 PM | 27,809 Views
So, here I am with a shedload of 2mm Depron. Question is, can I make a decent sized model with it?

Step 1, Make a CAD model of the aircraft.
Step 2, Approximate the compound fuselage shapes with a simple faceted version.
Step 3. Spend a merry few weeks printing, cutting and glueing parts together! Note that various moulds, forms, cylinders and other shapes available in the workshop were pressed into service to help form the required shapes.

I can recommend "Canopy Glue" as a really good PVA, though it takes a while to dry properly and can slow the build if it is the only adhesive used.

I am currently shaping and panelling up the rear and lower fuselage skin sheets
Posted by Swanlander | Jul 18, 2007 @ 03:59 PM | 29,642 Views
Flew the beast again yesterday afternoon, noticed that the yaw oscillation is rudder induced taking a few cycles to disappear. Also wind gusts caused wild roll changes.

I have looked at other biplane wing span/tail moment ratios and have come to the conclusion that the dihedral must be halved. I will attempt this at a later date when I have not impaired my senses with a couple of pints of beer!

The other issue with yesterday's flight was the loss of one ESC. It screamed as if the pinion grub screw had loosened, but worked when I launched. One minute later I had only one motor working. After landing, a sniff of the PC board confirmed that it had "let out it's smoke This was the first time I had tried a new set of Lipos on the second motor.
Posted by Swanlander | Jul 16, 2007 @ 06:52 AM | 30,914 Views
1. Vibration blurrs the video.

Solution:
Move the cg of the camera close to the line between the suspension points at the booms. Also fitted silicone tube isolators. No more problems.

Took her to Wales for the inaugural UK-AP meet, fantastic weekend!

2. Now there is no vibration, the video is almost watchable, except for the sick-making motion of the aircraft when straight and level. Looks like dutch roll of some sort. I suspect using the same dihedral as a monoplane SS (but with two wings) means it is spirally too stable.

Solution (I think!):
Increase the fin volume by extending the tail moment. After all, this is why I made the booms adustable. (I even left some extra servo cable length for this very reason!) Will try this when there is a weather window.
Posted by Swanlander | Jun 27, 2007 @ 07:00 AM | 29,881 Views
All up weight with 14oz Fuji 3500 is 44oz, which gives a wing loading of around 6oz / sq ft. Pitch stability is good, with plenty of elevator authority to flare deadstick. Slight yaw trim change under power, but nothing untoward. She climbs shallowly with the current motor, but this will be addresed shortly!

Turns are amazingly tight, and she flies very smoothly. I need to make all my control inputs very gentle, as the video shows up any small bootful of rudder.

I hand launched poorly on the third flight, having moved the camera back 2". The trim change meant a rapid pitch up, combined with an unintentional 45 degree bank at release!

I applied full right , plus down elevator and waited.........Amazingly she clawed her way back to straight and level and powered away majestically!

The low wing loading of 7 square feet of wing helped here, most other low powered models would have snap-rolled and bit the dust!

I have changed the camera mount to bring the CG of the unit close to the mount centres, also I fitted silicone tube anti-vibration mounts to secure the camera rail compliantly to the booms. Ground testing shows a marked improvement, with no noticable camera blur in video mode. More flight testing is needed now.
Posted by Swanlander | May 19, 2007 @ 04:08 AM | 30,184 Views
Now I have all the bits it is time to start!

Wings are fitted with 3mm dia carbon tube spars instead of the stock glass rods, the Trailing edge is cut off to insert the rear spar at the aileron hinge line. All fixed with heavy duty gaffer (Duct) tape as I don't trust the transparent film supplied. Holes were pre-cut to fit and bind the interplane struts to upper and lower wings.

Now I have to make a jig to support the wings in their relative positions so I can bind the struts to the spars.

19/05/07
Posted by Swanlander | Feb 03, 2007 @ 09:43 AM | 30,595 Views
Now the aircraft modification is just about as I want it, here are the stats:

Fuselage + Wing supports, 3 servos, ULTRAFLITE D/13/32 motor,
3:1 ratio turning APS 9x6 Prop,Tsunami ESC and camera mount = 450g
Flight Battery 1200 "Flightpower " 3p1s lipo = 81.4g
Wings Strengthened and fitted with 2 servos = 180.5g
Fuji E900 camera with 2x AA cells = 220.0

Total = 999.0g (35.5 oz)
Wing loading is 10.14oz/sqft

(Stock slowstick has a wingspan of 46.3" and area of 505 square inches = 3.5 sq ft)

Next SS to be a bipe



3rd February 2007