Wright Stuff B

[gh]

Agh, that's right. Disregard what I said earlier. I haven't built a plane for a year, and I've forgotten everything. :\

[jander14indoor]

As far as I know, it should be exactly the same length as the distance between your rear hook and prop hook. Any longer will result in slack that won't give you turns.

You will theoretically get more power if you stretch it further, but at the expense of turns. You'd be better to get thicker rubber if you need more power.

Since rubber thickness is one of your tuneables to make your plane fly well (see Doug Schaefer's note), you'll be lucky if you can match the length of the motor to the distance exactly anyway. Those last few turns are at very low torque so carry little energy. Make the distance about the length of the fattest 1.5 gm motor you plan to use and don't worry about it.

What ever you do use full amount of rubber allowed. Short ceilings need thicker motors and tall ceilings longer motors.

Listen to that advice! Mass of rubber is the same as fuel in a gas tank, fill your tank and use the max allowed, 1.49999 grams this year, EVERY time.

Advanced concept. There are some classes of indoor flying where rubber isn't limited. In those cases there are practical and theoretical limits best learned by practice. But in severely rubber limited classes like Wright Stuff, use every bit you can.

Jeff Anderson
Livonia, MI

[bob3443]

In regards to the prop...use a good thrust bearing and some very straight wire (I used to get the Ikara/attachment from Harlan). I suppose a little graphite between the thrust bearing and music wire would reduce friction, but probably negligibly if you've got a good fitting prop assembly.

isn't a thrust bearing way too heavy?

[andrewwski]

jander14indoor...it would be a rough distance. Changing the rubber thickness and keeping the mass the same would only affect the motor length minimally, so I'd use the the length of the thickest motor (as you recommended).

bob3443...huh? You need to use a thrust bearing...

[bob3443]

Just to let you know, this is my first time building a plane, so i have no idea for most of the stuff. Can someone tell me how the thrust bearing is attached to the propeller and motor stick? I'm still lost...

Also on the rules it says on 2.e. "The Propeller Assemblies may be built by the competitor(s) or purchased pre-assembled. It may include a propeller, a shaft, a hanger, washers and/or a thrust bearing. The propeller must be a single two-bladed commercially made plastic propeller with a maximum diameter of 20.0cm. ..."

First it says that it can be handmade or bought, then it says that it MUST be a commercially made PLASTIC propeller.
I don't get it... am i allowed to make a propeller? Do i need to use plastic? Can I use other materials such as wood, fabric, foam?
And yes, I got these from the OFFICAL rules from my coach.

[andrewwski]

OK, here's where you need some clarification.

The "propeller" and the "propeller assembly" are not the same thing. The "propeller" is only the propeller...or the two blades and the method they are attached together. You must get a commercial propeller - you cannot make one. The best prop to use is known as the Ikara...there are two main versions for WS, the "fat bladed" and "narrow bladed."

The "propeller assembly" is the materials used to attach the propeller itself to the motor stick and the motor. Generally, this involves the thrust bearing, which has a wire going through it that attaches the prop and motor, and it gets attached to the motorstick.

Maybe this diagram that I sketched better explains it:



I'll see if I can take a picture of one of my old planes tomorrow to better illustrate.

[smartkid222]

I think carney would do a good job explaining it. I spent 10 min now going through my AIM logs and i cant' find that conversation we had about this.
Actually all i can find is:the thrust bearing is a little red ball with a hole in the center. pretty much a bead. and it makes so the prop spins. its on the prop assembly.

And can someone please tell me how you just put a picture inside a post. LIke physicly what did you do. I'll post a pic if you people tell me.

"sketch" lol

[fleet130]

And can someone please tell me how you just put a picture inside a post.

To add a picture to your post:
1. Upload the picture somewhere on the internet.
2. Add the URL for the picture's location to the text of your message and enclose it in BBCode image tags.

Like this:

Code: Select all

[img]http://soinc.org/sites/default/files/layout/ads/store.jpg[/img]

Will show the image:

You can even add a link to the picture like this:

Code: Select all

[url=http://store.soinc.org/][img]http://soinc.org/sites/default/files/layout/ads/store.jpg[/img][/url]

Here's some photos from the archives:





Note that these only show the parts. There are many different/better ways they can be made.

[bob3443]

Thanks sooooooooooooooooooooooooooooooooooooooooooooooooooooo (times10000000000000000000000) much. now i basicly get everything, but i still have questions. what's the difference between a fat bladed and a narrow bladed propeller? Also, did you make the propeller assembly yourself or did you buy it? What is it made out of?

[andrewwski]

There's two types of Ikaras...as the name implies, fat-bladed and narrow-bladed. Dave Ziegler sells both of them on his site, with the assemblies already attached:

http://freedomflightmodels.com/paypal.htm

However, I would not recommend using those plastic attachments. There's no good way to keep them attached to the motor stick, and the hooks are so tiny that it's hard to get the rubber or o-ring on them.

Harlan also sells the fat-bladed without an assembly:

http://indoorspecialties.com/index1.html

I'd definitely use Harlan's thrust bearings regardless though. He sells ones specifically for SO, but some people here have still recommended using the pennyplane ones. I used the SO ones last year and they worked well.

http://indoorspecialties.com/index1.html

If using those bearings you'll probably want a small bead or piece of teflon tubing to separate the prop from the thrust bearing:

http://indoorspecialties.com/index1.html

I've used both the fat bladed and narrow bladed Ikaras...I can't say I liked one over the other. If adjusted to the correct pitch, either one seems to work well.