1. In one of the steps of the build, it says mount the wing on the fuse with two #67 rubber bands, then straighten out the wing and mark it somehow.

It sure takes a lot of force to stretch those rubber bands on. It seems that when I eventually put 12 rubber bands on to hold the wing on well enough to fly, that the dowels would break. Seems like they should be metal or at least something stronger.

Has anyone heard of those dowels busting in flight? If one of those goes, the whole plane will be a pile of sticks.

2. I bought two APC propellers. However, the instructions say that wooden props are recommended. However, most of the guys on this forum, seem to use APC. Are all APC props nylon? What is the stregnth difference between a wooden prop and a grey APC prop?

3. My plane is a tad tail heavy. I am thinking of getting a prop hub. However, I am not totally sure what they look like. I would imagine they look sort of like a lug nut on a car wheel. These screw on over the prop and get masked by the spinner right? Are the threads on these all some standard? (i.e, I only need to shop for the proper weight)


I think that is it. Thanks for your reply on any/all of these.

1) Yes, I've heard of wing dowls failing in flight, but usually because it ripped through the top of the fuse that was built wrong. It's far more common for someone to not put enough rubber bands on there, and have the rubber bands fail, with obvious result. So, don't worry, those kit provided dowls will do the job. (what's the kit? If it's a even half-well designed kit, then you've nothing to worry about)

2) APC only makes nylon as far as I know. Don't worry about the instructions saying to use wood. APC props are actually fairly fragile, espeically near the tips, because they are so thin. And they are sharp, as you noticed. For learning, I usually recommend the black Master Airscrew props, you'll break less of them. Wood props probibly break easiest on things like nose-overs or rough landings, with APC in between wood and MAS

3) There are several differnet brands of weighed prop nuts. Some of them are used instead of a spinner, and work with the electric starter just as well.

They are NOT all the same size. Differenet engines in different sizes by different companies use different threads on the crankshaft. Some are english, some are metric, etc. So you have to make sure that whatever you buy will work with your engine. If the engine instructions don't say what the crankshaft threads are, post what your engine is, and someone here might know, or ask in the engines forum.

My brothers dowell broke in half during flight. It was reduced back to a kit after that! If you are building it from a kit, and feel comfortable making some mods, then make it a bolt on wing. If you use 12 or more rubber bands, then a nylon bolt will give you just as much break away (or more), and is much more secure. My dad and I changed my trainer over to bolts and I haven't regretted it since. Of course, I don't fly it as much anymore, but when I want to, it's nice! This requires a few mods, so if you're not comfortable with that, then stick with the rubber bands. I might suggest changing dowells every few months or so. I think after they get fuel soaked a few times they get weaker. Don't use dowells you find at lowes or other places, they don't seem as strong to me. Maybe they are, but they don't seem to be. Go through the manufacturer, or LHS.

I would definitely start with the black master air screw props for a few reasons. First, they are cheap. Second, they are not as sharp as the apc (or spinning razors), and third they are not nearly as fragile as either. If you go APC or wooden later on, you'll need to go down a pitch or two from the MAS because they don't flex like the MAS props do. For example, if you turn an 11 x 7 MAS, then you might want to go to an 11 x 6 APC or wooden. Your engine might handle it, but my .46 trainer engine loads too much with the higher pitch APC and wooden props.

As montague said, you need to find the correct spinner nut for your engine. If possible, though, I'd simply slide the battery as far forward as possible, and if that doesn't do it, add a little bit of hobby weight under the fuel tank or something like that. Try not to put a heavy prop nut on that little engine. It simply adds mass that the engine has to turn, and you loose some of your power that could be transferred to the prop. However, sometimes a prop nut ends up being the best way to balance a plane--whichever works for you. You definitely do not want a tail heavy plane. Nose heavy planes fly, tail heavy planes crash....

Master airscrew props are real sharp. i found out just by taking it out the package. i also held the prop as i was tightening it and it cut through my hand like a knife through butter. i now alwys use a welders glove anytime i hold tprops when tightening them or even starting the engine. I only owned 1 plane that used rubber bands and hated it so much i changed it to bolts. we had a guy at our field that did not change the rubber bands as often as he should and the rubber became weak and brittle because of the fuel/oil. that wing looked so pretty floating down to the ground

When you take a MAS prop out of the package, it has a lot of mold flashing. You want to sand or shave that off. You'll actually pick up RPM by doing that, and the prop is more efficeint, you get more pull, and the prop isn't as sharp. APC props also have flashing, but not as much. And they should have really sharp TE's.

Also, be sure take any price tags or saftey stickers off. And you should balance your prop as well.

Wing dowls, if they are exposed wood, should be fuel proofed, like any exposed wood. I wipe some epoxy over them. Yes, you can modify the plane to take a larger dowel if you want. Just be sure you don't weaken the area that holds the dowl in place. If you want to do a bolt conversion, you can do that too, but I've actually seen more wings come off when a botched bolt conversion let the bolts pull through the wing than I've seen dowel failures. Fwiw, I use hardware store dowels all the time with no problem. Just look for ones with a tight, straight grain.

when you put the elastic bands on the dowels are you trying to get the rubber band around the 4 ends of the 2 dowels at the same time or are you just pulling over 2 ends of the 2 dowels at the same time. a newbie might try to go around all the dowels at the same time while some one experienced would not think of it. I have gotten by with 10 bands easily, just remeber to criss cross the last ones to hold the bads onto the dowels so they do not slide off. if tail heavy try to move the battery forward before putting dead weight on. this is not as important on a trainer but when you get into higher performance planes the weight makes performance suffer

I'm just going to put a BIG DITTO to BOTH of Montegue's posts

The above posts are good advise. For get wooden props!! They are expensive and the slightest touch against them when the engine is running and they will instantly snap in 2!!! For training the MAS props are the most strurdy and work just fine. You never said what size engine you have so I can suggest 11-5 prop for a 46 size engine and a 10-5 prop for a 40 or 42 size engine. [8D]

I agree wooden props do break easy... However, what you have to remember is that's exactly WHY they recommend them for a trainer.. If you stick the nose in the ground, the prop will break way before the motor, motor mount, firewall, etc.... Generally MA or APC will too, but there is a chance of causing some other damage... Course if you have a competent instructor, chances are you'll never break a prop regardless of it being plastic or wood..

Back when I was learning to fly, I was told the same thing, that you want wood props because the torque coming back in to the engine from a plastic prop hitting something could damage the engine or the airframe.

It might have been true many years ago. (many many many years ago), but it's BS now. There's not a modern engine out there that will take any damage before the blades shear off. Ditto the engine mounts or firewall.

If you auger in, the sudden stop you're worried about isn't the rotational one of the engine .

I've had more "sudden engine stops" flying combat with .15 and .25 engines than I care to think about. And engine or airframe damage due to something (the ground, another airplane, whatever) going in to the prop is a non-issue. And I've never seen anyone else damage an engine or plane due to the prop not breaking easily enough.

Of course, YMMV, but IMHO, the "wood props prevent damage" advice is out of date.

Oh, and wood props chop up fingers every bit as well as other materials as well. A wood prop will not break before it takes your finger off, if it comes to that. So, there's no safety advantage either.

Good advice here. Thank you all for that.

Its an LT-40 kit. The motor I am using it an OS .46AX. Anyone know the thread size on that?

I am going to use the two APC props (hopefully just one ). I have heard that APC props are more efficient than the Master Airscrew props that is why I elected to go for those instead.

Accoring to osengines.com, that engine uses a 1/4-28 crankshaft. That's the most common small (.46 down to .25) size crankshaft size.

With that engine and airframe, you have power to spare. The extra efficiency of the APC is totally not needed. Not that you shouldn't use the APC's, just that popping a MAS on there won't hurt.

You'll probibly need more than 2 props. Though 2 will get you started.

Thanks for the quick reply. At this point, I just really want to fly the thing. I have been wanting to fly for a while, but decided to take the kit route. So I've had a big speedbump here in front of me for a while. Its nearing the end and I am just anxious to get some stick time. My total stick time to date is about 1.5 minutes. That consisted of about 15 takeoffs and 1 landing (do the math to figure the # of crashes ) on a slow stick.

I can tweak this thing after a few flights. I might do a taildragger conversion and the bolt on wing. But for now, FLY FLY FLY, is the name of the game.

I agree with the bolt on wing conversion but the converting to a tail dragger isn't worth it on this plane. You can email me for instructions on how to convert the wing.[8D]