Twin Star plug-in trike undercarriage - RC Groups
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Oct 28, 2003, 03:27 PM
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Twin Star plug-in trike undercarriage


Details of this were originally posted about 3 years ago and have since fallen off the Forum. The plane is still going strong, I recently had an email asking for details & pics of the u/c again so I thought I'd re-post. For 'old timers', there's nothing new here ... it's all still working fine!

The basis for this is square section brass tube (available in LHS in UK, "K&S" brand I think?) which comes in different sizes that are a sliding fit inside each other.

First piece runs sideways through the fus., this has a flat plate approx 1" wide soldered along the top face to stop it twisting in the foam under load. Use a sharp tube (old TX aerial etc.) to pierce the hole through the foam then open up a slot for the plate with a junior hacksaw blade. Plug the end of the brass tube (so you don't get glue in it) then epoxy it into the foam - when dry, trim it flush and you can use a little patch of silver duct tape to neaten it up!
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Oct 28, 2003, 03:31 PM
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OK, the noseleg tube goes vertically up from the centre of the front moulding mark on the fus. underside, don't go up too far or you will come out into the air intake in front of the cockpit!

The noseleg tube can be quite a bit thinner than the main gear one, see later for dimensions. Make sure you plug the top end firmly before you glue it in (epoxy again).
Oct 28, 2003, 03:39 PM
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Here are the U/C legs. You can bend the coil spring in the noseleg easily around a drill bit clamped in a vice.

The square section brass tubes obviously need to be the size below the corresponding bit that's fixed into the fus. To stop the legs dropping out you can very slightly crush the leg part of the tube in a vice to distort it fractionally. Don't over do this or you won't get the legs in (or they'll go in but not come out again!). You're looking for a tight sliding fit.

The main legs are angled back slightly, see later pic.

Dimensions:

Nose leg is 14 SWG (approx 2mm diameter), wheel is 1.75", brass tube is approx 4mm square. Weight of completed noseleg & wheel is 21 grams.

Main legs are 10 SWG (approx 3.5mm diameter), wheels are 2" diameter, brass tube approx 5mm square. The main legs complete with wheels weigh 65 grams in total.
Oct 28, 2003, 03:42 PM
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Shot from underneath with the gear plugged in, you can see the main legs raked back slightly so the wheels are just behind the CG.
Oct 28, 2003, 03:46 PM
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Shot from the side, dimensions aren't critical but the plane should sit level. The longer the legs are, the more leverage they will exert on the fus.

Mine has been slammed into the ground so hard that the nosewheel made a recess in the fus underside (doing touch & gos on a rough strip in very windy weather) - nothing broke, the model bounced back into the air and flew away as if nothing had happened
Oct 28, 2003, 03:51 PM
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For steering on takeoff you really want as much rudder throw as you can get. I found the supplied wire rod was too stiff and caused the rudder servo to stall with increased throw, substituted a more flexible plastic rod ... that works much better and allows about 45 degrees each way! I have never had to abort a takeoff, a steerable noseleg would be nice for taxying but it's not necessary otherwise (nor is an enlarged rudder).
Oct 28, 2003, 03:54 PM
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Use the outermost hole on the rudder servo arm (top servo in this pic., the other stuff you can see is the wiring and switch servo for the lights! ).
Oct 28, 2003, 03:56 PM
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Whole model (before fitting the lights). 6V S400s, 4:1 gearboxes, APC-E 11x8.5 props, 8x2400 nicds.
Oct 28, 2003, 03:58 PM
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Radial cowls from (IIRC) face cleaning pad pots!
Oct 28, 2003, 04:00 PM
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Nose (landing) light is the reflector from a Maglite Solitaire (AAA size flashlight) with a hyper bright white LED instead of the bulb.
Oct 28, 2003, 04:02 PM
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Switched on (too bright to show pointing directly at the camera!).
Oct 28, 2003, 04:03 PM
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TE lights, red on left wing green on right (hyper bright LEDS).
Oct 28, 2003, 04:05 PM
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LE and tip lights, again red on left wing and green on right. There are also large (10mm) flashing ultra bright red LED beacons above and below the fus.
Oct 28, 2003, 04:09 PM
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The lights run directly from the flight pack, you can see the thin wires running back from the 4mm gold connectors. The LEDs are wired in series clusters with resistors where necessary to drop the voltage. They are switched by an HS-50 servo operating a micro switch.

Hope that's all clear, if not let me know and I will answer any queries.
Oct 28, 2003, 05:32 PM
Sloping off....
leccyflyer's Avatar
Brilliant Bill!

Thanks very much for reposting this, I'm sure that the new generation of Twinstar pilots will find it very useful and maybe even a few older Twinstars might get rejuvenated and retrofitted with a nice set of wheels.

cheers

Brian


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