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Posted by CaseySP | Apr 05, 2020 @ 05:22 AM | 3,771 Views
Latest version of the Alfa Corsair retracts. I haven't flown this for some time with the wing modified for flaps/retracts as the earlier version of the retract actuation became more and more unreliable.

Thanks to a bit of spare time lately with our airfield closed due to COVID-19, have pulled the wing down from the shelf for some more tinkering.

This looks quite promising - very robust and reliable. Was able to replace the HS-81MG servo (17g) with a lighter Turnigy TSS-10MG (10g) - so maybe a neutral impact on weight allowing for the bell-cranks but removing the flexible Gold 'n Rods.

Alfa Corsair Retracts (0 min 38 sec)

Posted by CaseySP | Jan 17, 2020 @ 07:29 PM | 7,301 Views
This is how I (hopefully) increase safety by splitting power supplies. Using the otherwise unused ESC BEC power for non-essential servos to preserve power for the RX and essential controls, eg should the retracts jam.
Posted by CaseySP | Dec 28, 2019 @ 05:16 AM | 2,491 Views
Some progress on my new Alfa Spitfire.

This is my second one - the first one had an unfortunate demise (see below).

All of the electronics and retract mechanics are able to be re-used, and this has immensely sped the process along. Plus I actually learned something from all my mistakes on the first build - the retracts requiring some hours of enjoyable tinkering with a bit of trial and error and problem solving to get it all working well.

Only problem was I lost the functioning mirror I had made - lost to the gods of the outfield grass

Also spent some time on the firewall - checking all joints for glue adhesion and reinforcing this area....Continue Reading
Posted by CaseySP | May 19, 2016 @ 08:33 AM | 5,841 Views
Some pictures of the flaps and retract setup.

Both the retracts and flaps took some time and a few evolutions to sort out. The retracts are operated by a Turnigy TSS-10HM DS Micro Servo 2.2kg 10g servo and have a "pusher" cut from an old credit card to push open the doors as they extend. This keeps the doors from jamming the retracts and keeps them clear of the retract springs.

The pusher contacts a curved "runner" (also from old credit card) fixed to the inside of the gear doors. This is also shaped to form a ramp to increase the speed the doors open as they near the fully open position.

The retracts also have a length of elastic (elastic hair bands borrowed stolen from the wife). These are carefully tensioned to close both the front and rear of the doors neatly. Holes are drilled in the pushers to tension the elastic bands and pull the doors shut as the undercarriage retracts.

Each retract servo is on a separate channel and the endpoints are individually set to push the retracts to their mechanical limits (both up and down) and a curve then relaxes the servo by 1/4 mm or so. This means there is no load on the servo either when fully retracted or extended - all the load is taken by the "end locks" of the retract (no buzzing ).

Flaps are cut from 1.5mm balsa with strengthening ribs to make them slightly concave to keep the trailing gap at a minimum. Operated by a HXT500.

Clear plastic strip links the inboard and outboard sections....Continue Reading
Posted by CaseySP | Feb 20, 2016 @ 07:48 AM | 4,845 Views
Rudder and Steerable Tailwheel:

The rudder is simply cut free and uses the moulded-in hinging. I fitted two spare Alfa control horns to either side of the rudder to set up a pull-pull system.

For the tailwheel a Dubro semi-scale tailwheel system was modified. Modified in that most of the bits in the bag were discarded, and only the wheel, the wheel yoke and another piece or two were used.

The wheel was removed from the yoke; the mounting post for the yoke was punched out; the resulting hole was countersunk and a countersunk screw was fitted and glued into the yoke. This then can rotate in a blind nut fitted to a strip of hardwood (ice-cream stick).

The tailwheel control arm was fitted complete with two Alfa quick connectors that the rudder pull-pull wires feed through. The bottom of the fuselage was cut out (keep the cut-outs as they will be refitted) and the hardwood strip glued to the inside of the fuselage. Controls for the rudder and tailwheel were then adjusted for slop-free operation and correct throws.
Posted by CaseySP | Feb 20, 2016 @ 07:04 AM | 4,859 Views
Been slowly getting this together. Has been somewhat of a long build, with minimal time to work on it and some major interruptions along the way.

Model is an Alfa Beaufighter modified with retractable undercarriage and split flaps. The basic model goes together very quickly as do most Alfa's if left as a basic hand launch and belly lander. However the retracts and the flaps have each taken about twice as long as the rest of the model combined.


Motor: 2x Turnigy Aerodrive SK3 - 2826-1130kv
ESC: 2x HobbyKing 12A BlueSeries
Battery: ZIPPY Flightmax 1800mAh 3S1P 20C
Propeller: 2x GWS EP 8x4
Servos: Ailerons - 2x Futaba S3114; Elevator - Futaba S3114; Rudder HXT900; Flaps 2x HXT500; Retracts - 2x Turnigy TSS-10HM DS Micro Servo 2.2kg
RX: FrSky XR8 8 Channel Rx
Retracts: 2x Alfa 6001 retract sets.
Tailwheel: Modified Dubro DBR955 Semi Scale Tailwheel system

RFT weight : approx 750g
Wing loading: 46.88g/dm2 (15.56 oz/sqft)
Posted by CaseySP | Dec 24, 2014 @ 07:03 AM | 6,010 Views
Further progress adding retracts to the Corsair. The original servo for the retracts didn't have enough grunt to overcome the tight bend radius required. Swapped it for a HS81 for 2.6kg of torque.

The flaps caused some problems. The cheap 9g servo I had from the spares box burned out during testing/setup, so put in place a slightly less cheap HXT900 and redid the linkages to remove binding.

The wheel doors and other foam panels that were removed for the installation were reinstated with the appropriate bits permanently cut out to allow wheel retraction. Sadly I don't have the talent to do proper doors at this scale within the remaining weight budget.

The US Navy scheme paint was removed from the wing for repainting with the RNZAF tricolour scheme - airbrushed Tamiya acrylics thinned with windex.

Corsair 4Nov2014 (0 min 33 sec)

Corsair maiden (1 min 22 sec)
...Continue Reading
Posted by CaseySP | Apr 18, 2014 @ 09:32 AM | 6,530 Views
Have put 5 flights on the Mighty Knight since I finished the conversion and aileron work.

RTF weight with a 3000mAh 4S battery is 1760g - about 40g heavier then with the OS.32FSR with no fuel in the tank.

The aileron servo move has paid dividends with no hint of flutter yet. 8 minute flights with less then 80% capacity used. Very happy.
Posted by CaseySP | Apr 03, 2014 @ 07:13 AM | 6,687 Views
As mentioned below, relocating the aileron servos from the wing centre section torque rods to a more outboard position in an attempt to tame aileron flutter.
Posted by CaseySP | Apr 02, 2014 @ 07:31 AM | 6,535 Views
Power tests looked good at low to middle throttle, unfortunately at the top 1/4 of the throttle range a severe vibration started- sufficient to suspend any further testing.

This motor had been in a one-point landing in the crash of my Tiger Moth, I replaced the prop driver and shaft but on closer inspection the front bearing is U/S and the case may also be distorted.

Replacement motor is on its way - in the interim the power tests showed at about 3/4 throttle (when the vibration started and I cut the throttle):

44.98 A max
14.33 V min
645 W max
Posted by CaseySP | Mar 18, 2014 @ 07:02 AM | 6,839 Views
Have finally had time to fit the motor and ESC. Needed to relocate the servos to the rear of the battery hatch area to allow the battery to straddle the CG range.

Took the opportunity to replace the old "standard" sized servos (JR ES-539) for the elevator and rudder with HiTec HS-82MGs.

Will eventually make a cowl for it, probably fibre glass using the lost foam method.

Have also decided to move the aileron servos outboard in the wing. They were centre mounted operating the ailerons via toque rods. Problem was the Mr Whippy ailerons were able to flex at about 2/3 of their length causing significant flutter at high speed. Hopefully moving the horn to about the 1/3 - 1/2 length will fix this.

The inboard covering on the underside was stripped to access the hard balsa ribs and cut holes for the servo leads. Will be fitting low profile servos. Next job is to fabricate some lite-ply mounting plates and covers for the servos.
Posted by CaseySP | Feb 10, 2014 @ 05:33 AM | 6,984 Views
Battery hatch cut using my trusty Zona razor saws. Position worked out perfectly - taping motor and propeller into the airframe and positioning the battery to find the ideal place which by coincidence is under the canopy, on the CG.

Elevator and rudder servos will need to be shifted aft and the servo mounting plate removed to provide clearance for the battery plate.
Posted by CaseySP | Feb 07, 2014 @ 09:06 PM | 7,142 Views
First job was to remove the engine bearers - 4 layers of 3mm ply epoxied into place. The space between the bearers is too narrow for the motor to fit and they are not needed - the motor will be mounted using standoffs fixed to the firewall.

The rear most part was left in place. It will add some strength to the firewall (not to mention it was impossible to remove without causing damage).

0-2 degrees down thrust and 2 degrees side thrust required.
Posted by CaseySP | Feb 02, 2014 @ 06:09 AM | 7,561 Views
Converting an old MK Mighty Knight kit. Built it with mechanical retracts (tail dragger version).

Last flew about 8 years ago with a OS.32FSR on a 10x6 APC. Flew very fast, almost like an old pylon racer. Unfortunately the motor never ran very well possibly due to a compromised tank position (too low) - most landings were dead stick.

Converted to a two-servo wing (flapperons) - flaps on landing proved very effective (especially without the aid of a windmilling prop).

Weight prior to conversion without fuel 1730g.

To be fitted with:
  • Turnigy Easymatch G32 770kV
  • Turnigy DLux 55A ESC
  • Turnigy 4S 3000mAh 20C battery
  • 12x6 APC E (if there is clearance)

Posted by CaseySP | Aug 03, 2013 @ 09:30 AM | 7,507 Views
Catching up on the work completed to date. Wings completed, tested covering on ailerons and cowl constructed.
Posted by CaseySP | Apr 27, 2013 @ 09:03 PM | 9,518 Views
A colleague at work mentioned some time ago that his dear old Dad had started building a RC plane many moons ago but age/wariness/other interests over took the build. He gave the unfinished kit to his son who then had it stored in his garage for many years.

At the start of the year he asked me if I was interested, but to be honest I'm not keen taking over half-built projects as you can never be certain of the quality of the workmanship.

Anyway, fast forwards to now and I arrived at work to find a big plastic rubbish bag with bits of airframe poking out plonked in my office. Covered in years of dust and it looks like an oil change was performed over the tailplane.

Got it home to clean it up and it was far better then I dared imagine. My first ever plane back in the early '80's was also a Pilot kit - the Cessna 177. Brilliant kit, very very solid and supreme quality.

The kit seems very complete - only missing the clear plastic for the windshields as far as I can tell. The work so far is of very high quality and is a credit to my colleagues old man.

Link to an earlier find
Posted by CaseySP | Jan 10, 2013 @ 08:25 AM | 8,973 Views
Another build - another Alfa. The Albatros D.V has always been one of my favourite WWI fighters (along with the British Bulldog and Gladiator), and is one I've had my eye on since it was first released by Alfa.

This time I used the surface mail shipping option as I had a couple of other projects underway, so opted to save a few pennies on postage.

The Albatros took 10 weeks to arrive. On opening the box - what a beautiful little aircraft - usual Alfa quality. No shipping damage, the only problem is that one of the ply blanks for the undercarriage legs and struts had a split in it right through the cabane strut. A few drops of CA fixed it.

I decided on a COBRA C-2203-46 KV1720 motor after reading positive reviews of this motor fitted to the Albatros (thanks NSG).

Power system:
  • COBRA C-2203-46 KV1720 motor
  • Hobby King short prop adapter M5x3mm shaft (Grub Screw Type) - NB fitted a plain M5 nut and washer
  • GWS 8x4 SF prop (black)
  • TURNIGY Plush 10 amp 9 gram Speed Controller
  • ZIPPY Compact 350 mAh 2S 25C Lipo Pack

3 x HS35MG servos (4.5g) are on order for the control surfaces - yet to arrive.

Construction is very straight forwards - slip the tailplane into place and glue with Weldbond, checking for alignment.

With the lower wing, the centre needs to be found and positioning marked. This is important as I chose to use UHU Por (contact glue) so there is not much working time to resolve the alignment once the glue grabs. But it saves having to pin or clamp the...Continue Reading