1/4" staudacher

[twest]

Well, I found my long-term project:

a Creek hobbies (out of buisiness?) 1/4" scale staudacher. The wingspan is only 74", but is IMAA legal due to true 1/4 scale.

It is a bit heavy, but I bought it on ebay for $65!! It was flown with a glo engine. All servo locations have been worked out- luckilly for me, the previus owner used pull-pull systems for rudder and elevator. I will most likely use the same setup, as elctric motors tend to be lighter than large glo/gas engines. This plane has a reputation for being tail heavy, so I might put the motor and batteries in the cowl.

Anyway, here are the pics:

[twest]

The cowl is huge, so plenty of room for motor and battery if needed. There already is a significant cutout on the bottom of the cowl, so access to batteries there might be easier than in the fuse (only a small hatch on bottom).

Weight was 11.5 lbs with 1/2 lb of lead in the nose, and a 32 oz. engine. With lipos and my preferred geared inrunner type setup, I'm shooting for the exact same flying weight.

There are a few simple areas to reduce weight, other than taking out the 1/2 lb of lead in the nose: the aluminium wing tube is like a baseball bat, and the landing gear is like a rock. Both will be replaced with carbon units.

Anyway, this will be a fun project, my first "larger than .60-sized" plane, and if it works out well I can transfer the equipment to a new arf in a year or two.

[jason H]

Hey Twest, the Studi looks great. Keep us in the loop as to how you go with it.

[karl k]

Looking forward to seeing the rest of this conversion.

Karl

[twest]

Update:

I'm going slow on this one, I build about 1.5 new planes per year (I'm also restricted by law to working 80 hours per week on average as a surgical resident, and have wife, etc..)

Anyway, I've bought the motor and esc for this plane: an astro 60 geared, and a castle pheonix hv 85. Both new in box waiting for me to work on it. All I need now are the servos and a lithium pack (christmas?) and I'm good to go. There really is very little to do on the plane, as it is not an "out of the box" arf, but one that has been built, flown, and had the equipment removed.

[twest]

The servos are installed, and the motor is mounted. I'm using 4 jr digitals on aileron and elevators, and a hitec metal gear on the rudder.

[twest]

It won't be long now.

I ran the motor up today with the watt meter and tachometer.

Motor: astro 60 3-turn geared 3.1:1
ESC: Castle Phoenix 85hv
Battery: 8s 4900 Zippy pack (total cost $140)
Propeller: APC-e 20.12 wide blade

The motor turns the prop at 5800 rpm, 75 amps, 28.2 volts, 2100 watts.

I plugged those numbers into several calculators, and the estimates have ranged between 90.5% to 91.5% efficiency.


The overall weight, ready to fly, is 11lbs, 2 oz, which is lighter than the glo weight, 11.5 lbs! I did need to use a 2 oz harry higly heavy hub to get the plane to balance.

I'm excited about bringing this one out later this month, weather permitting. 190 watts/lb, 10.7 wing cube loading, 2:1 thrust:weight = fun!

[twest]

I took it up today, and everything went well. I setup the throws and CG exactly like the instructions. I might add a little bit of nose weight. The 20-12W prop pulled with plenty of thrust, but might need a little more pitch speed, so I'll try a 20-13 next.

Knife edge flight required a lot of up elevator, I might be able to fix this with more nose weight, but I will also use some rudder/elevator mixing.