Multiplex TwinStar with Landing Gear

and Lights,  from Bill Glover


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

 

The TwinStar is one of the most successful plane around. Easy to build, inexpensive, easy to fly and repair. Well, just a great plane. One thing many pilots were asking for, was how to customize it in order to install a full working landing gear.
And this is what Bill did, and the result is quite impressive. Bill published this within a Thread on the Ezone and was kind enough to let me share it here as well.

For further questions regarding the Setup, you can contact the author, Bill Glover at: bill_w_glover@yahoo.com
 

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 fuse., 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!

 

The noseleg tube goes vertically up from the centre of the front molding mark on the fuse. 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).

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 fuse. 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 picture.

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.

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.

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 fuse.

Mine has been slammed into the ground so hard that the nose wheel made a recess in the fuse underside (doing touch & goes 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

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 steer able noseleg would be nice for taxiing but it's not necessary otherwise (nor is an enlarged rudder).

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! ).

 

Radial cowls from (IIRC) face cleaning pad pots!

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

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

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

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 fuse.

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.

Question from the Thread:

Quote:
Originally posted by AMTJIM
Is that box tubing all you have for the main gear? I would think that thing would rotate with so little surface area.


The main gear cross-tube has a flat plate soldered to the top face to stop it turning in the foam. I used thin sheet brass for this because I had some, but tinplate would be fine. The plate is maybe 1" wide and runs along about 3/4 the length of the tube - the dimensions really aren't critical. Once you've pierced the hole through the fuse. for the tube, pass a junior hacksaw blade through and a couple of strokes each side will open up a slot for the plate.

I fly mostly off a really rough dirt/stones club strip and it's not had any problems in nearly 3 years. I mentioned it being slammed hard into the ground by a downdraft while doing touch & gos in windy weather (the strip has trees all round, so it gets very turbulent) ... in the underside view in pic #2 you can still see the dent the noseheel made when the noseleg sprung right back in this impact, the main gear never moved.

Couple of things I forgot to say last night.

First, the actual piano wire (music wire) legs are soldered into the bits of tube that plug in to the fuse., this is pretty obvious but I thought I'd better mention it! If you have problems with this you might be able to roughen up the surface of the wire with a coarse file and epoxy them in. That would certainly be fine for the noseleg as there's very little load on that. I suspect it would be OK for the main legs, but obviously I haven't tried it.

Second, the gearboxes & big props were a later conversion - I flew it with the u/c for some time using the stock direct drive motors on 8 cells. It ROG'd fine like this from average/smooth grass, the big props just give much better acceleration on rougher/longer grass.

Level speed is down a little with the gearboxes but duration is improved (and better acceleration, as mentioned). I have the ESC brake switched off so the props freewheel with the throttle cut ... this allows a steep landing approach (with the props acting as airbrakes), very useful in calm conditions as the stock TS is a real 'floater'. Oh and it looks pretty coming in like that with the nose light blazing away!

Actual Posts from Bill Glover, on the Ezone.