Twin Star plug-in trike undercarriage

Bill Glover · Oct 28, 2003, 03:27 PM

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!

Bill Glover · Oct 28, 2003, 03:31 PM

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).

Bill Glover · Oct 28, 2003, 03:39 PM

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.

Bill Glover · Oct 28, 2003, 03:42 PM

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.

Bill Glover · Oct 28, 2003, 03:46 PM

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

Bill Glover · Oct 28, 2003, 03:51 PM

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).

Bill Glover · Oct 28, 2003, 03:54 PM

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!

).

Bill Glover · Oct 28, 2003, 03:56 PM

Whole model (before fitting the lights). 6V S400s, 4:1 gearboxes, APC-E 11x8.5 props, 8x2400 nicds.

Bill Glover · Oct 28, 2003, 03:58 PM

Radial cowls from (IIRC) face cleaning pad pots!

Bill Glover · Oct 28, 2003, 04:00 PM

Nose (landing) light is the reflector from a Maglite Solitaire (AAA size flashlight) with a hyper bright white LED instead of the bulb.

Bill Glover · Oct 28, 2003, 04:02 PM

Switched on (too bright to show pointing directly at the camera!).

Bill Glover · Oct 28, 2003, 04:03 PM

TE lights, red on left wing green on right (hyper bright LEDS).

Bill Glover · Oct 28, 2003, 04:05 PM

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.

Bill Glover · Oct 28, 2003, 04:09 PM

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.

leccyflyer · Oct 28, 2003, 05:32 PM

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

Oct 28, 2003, 03:27 PM	#1
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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! Attached Thumbnails 44.6 KB · Views: 1835

Oct 28, 2003, 03:31 PM	#2
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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). Attached Thumbnails 46.6 KB · Views: 1692

Oct 28, 2003, 03:39 PM	#3
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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. Attached Thumbnails 38.8 KB · Views: 1885

Oct 28, 2003, 03:42 PM	#4
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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. Attached Thumbnails 35.0 KB · Views: 1681

Oct 28, 2003, 03:46 PM	#5
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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 Attached Thumbnails 53.4 KB · Views: 1774

Oct 28, 2003, 03:51 PM	#6
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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). Attached Thumbnails 37.0 KB · Views: 1650

Oct 28, 2003, 03:54 PM	#7
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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! ). Attached Thumbnails 60.7 KB · Views: 1860

Oct 28, 2003, 03:56 PM	#8
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	Whole model (before fitting the lights). 6V S400s, 4:1 gearboxes, APC-E 11x8.5 props, 8x2400 nicds. Attached Thumbnails 57.6 KB · Views: 1770

Oct 28, 2003, 03:58 PM	#9
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	Radial cowls from (IIRC) face cleaning pad pots! Attached Thumbnails 29.8 KB · Views: 1707

Oct 28, 2003, 04:00 PM	#10
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	Nose (landing) light is the reflector from a Maglite Solitaire (AAA size flashlight) with a hyper bright white LED instead of the bulb. Attached Thumbnails 35.5 KB · Views: 1578

Oct 28, 2003, 04:02 PM	#11
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	Switched on (too bright to show pointing directly at the camera!). Attached Thumbnails 19.7 KB · Views: 1537

Oct 28, 2003, 04:03 PM	#12
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	TE lights, red on left wing green on right (hyper bright LEDS). Attached Thumbnails 33.7 KB · Views: 1565

Oct 28, 2003, 04:05 PM	#13
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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. Attached Thumbnails 24.3 KB · Views: 1563

Oct 28, 2003, 04:09 PM	#14
Bill Glover Registered User Join Date: Nov 2000 Location: Bracknell, Berks, UK Posts: 8,658	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. Attached Thumbnails 46.0 KB · Views: 1542

Oct 28, 2003, 05:32 PM	#15
leccyflyer The guy from School of Rock! Join Date: Sep 2000 Location: NW England Posts: 9,816	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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