New to gas here. I'm ready to drill the mounting holes in my prop, but don't know how the holes should be oriented to the prop hub. If the prop tips are at 3 and 9 o'clock, are the holes drilled at 12, 3, 6, and 9 o'clock or are they drilled at 1:30, 4:30, 7:30 and 10:30? I've got to think that that there's a right and wrong way to do this. I've got a drill guide, but no instructions on how to use it. What do you guys do?
Engine = DA50
Prop = Wood Zinger 22x8
Thanks to all in advance
Paul

They way I understand it, there are two considerations. Since the grain of the wood runs along the length of the propeller, it's best not to have two holes along the same grain line (less chance of splitting). So the orientation you described would not be recommended.

Also you want to have a prop tip at around 2 o'clock with the engine at compression. That way you have the best chance of starting when you flip the prop over.

I do not think the orientation matters much, since each prop half will have three holes that weaken the hub. Choose such, that you get the best prop position for starting. For me that is the two oçlock prop position at compression start.
Just be sure to drill from the back, so the holes line up to the threads.

I like to have my prop at 1:00 when you are at the start of compression. With the DA50, you can turn the prop hub by hand without the prop on it till it comes up on compression. The magnet on the hub will be at almost 12:00 or 11:00. Check and see where the bolt holes are on the hub, then put your prop jig in your prop from the rear in the same position. The DA prop jig works so well though it really doesn't matter which side of the prop you drill from. You'll want to bolt the jig to the prop with 1/4 x 20 bolt and flat washer. That keeps the jig from moving while drilling all the holes. I use a #5 bit. Oh, one more thing. The DA50 center bolt is 10 mm. In order to use your drilling jig, you'll first have to drill out the center 1/4" hole to 10mm. B&B makes a real nice bit for doing this. It has a center pilot shaft that is 1/4" and the outer portion is 10mm. If you don't have this type of bit, it's very hard to drill it out without getting the center hole off center. If you don't have this bit, you are better off to use a step reamer to keep the hole centered. It just doesn't take much to screw it up....... Don't forget to re-balance after drilling the prop.

http://www.bennettbuilt.com/

No one yet has commented on your prop. I think most would agree that Zinger props make good paint stirrers but should not be used as airscrews if at all avoidable. There are, however, many good wood props out there, 3W, Menz, Bolly, DA etc. I would also suggest that eventually you will be much happier with a 22x10 on this engine. The 22x8 will seem to leave the model stuck in first gear.

Gerry, I know that the Zinger is probably not the best choice in props, but for my first shot at this I didn't wan't to screw up a $50+ prop. DA reccomends a 22x8 for breakin, so I thought I go with those numbers to start. No one has really addressed my initial question, though, regarging the orientation of the holes in the prop hub.. Some say it doesn't matter, but I have a hard time believing that. Others didn't read or understand my post fully. The DA50 has a 4 bolt prop not a 6. What are your thoughts on the orientation of the 4 bolt holes?
Happy flying,
Paul

One thing I did to keep the splinters from happening on the exit hole while drilling: Drill almost all the way through the prop but stop when you start to see the bit popping through. Turn the prop over and just open up the hole from the other side. Makes it much cleaner, no splinters.

I like the tips I read here. I never thought of bolting the drill jig to the prop, even though it seems kind of obvious now.....

What I did was put a bolt through each hole after I drilled it to hold the jig in place on the prop. Also I used the biggest drill bit that will go into the drill jig. That way I have a little forgiveness so the bolts thread into the prop hub without side binding. If the don't you can always open the holes just a little with the same drill bit. Works great.

I think Master Airscrew makes even cheaper props. They make excellent shoe horns for you ARF fliers that don't stir paint. I must admit I am not into $50 props.
For drilling the bolt holes I get a brad point bit. It drills a better hole. A standard bit will wonder according to the hardness of the wood no matter what the quality of the drill guide is.

Your Zinger will be just fine for break in.. Go out and fly, have some fun, learn the engine and working with gas, THEN spend a few bucks on a good prop.


When you bring your prop hub up on compression and put your prop on so it's at 1:00 and 5:00, you'll find that each of the 4 bolts will be in a different grain of the wood. Not much, about the diameter of the bolt, but that's enough so you don't have to worry about the prop splitting. I've yet to have my DA 50's backfire or kick back when starting them, and I would think this is when the best chance for a split prop would be. They just don't kick back like 4 strokes.....normally.

It really doesn't matter how you drill the holes for the prop - honest. Just arrange it so that your prop is at a convenient angle for you when you flip it through compression. BTW - this engine seems to like being thrown through the compression stoke rather than flipped hard. It just seems to start more easily that way, I don't really know why. This is true of many of the electronic ignition engines.

On my DA I drill my props with the 1:30, 4:30, 7:30, 10:30 pattern. Works fine. There is always the Zinger bashers that chime in. True, they are not the best props in the world but they are cheaper and usually easier to find. What you really need to do is define what you expect from the motor/airplane combination. You did not mention you aircraft. If you are looking for ultimate 3d performance, you can definitely do better. For general sport flying, your Zinger will work fine.

Mike

People seem to get the impression that a quality prop is expensive. If you mean carbon fiber maybe that's true, but excellent wood props are very competitive with paint stirrers:

BME: 22 x 8, 10, 12 - $25.00
Bolly: 22 x 10 $32.00 22 x 8 $32.00
Menz: 22 x 8, 10, 12 $25.00

These are prices taken off the BME and Desert Aircraft websites. What does one pay for a Zinger - $18 maybe $22? Is the aggravation of lousy performance worth $5 when the engine cost $600? Props REALLY do make a difference!

I agree with that assessment. I had to enlarge the center hole in my Zinger propeller to 10mm. Later, I bought an NX Propeller from Airwild Hobbies for just a little bit more. The 10mm hole was already drilled and it appears to be of much nicer quality.

http://www.airwildhobbies.com/MoreIn...t&level=2&id=7

Drilling out the center hole wasn't that hard, but I had to make sure the hole didn't wander while drilling. I used a stepped reamer in my drill press and then followed up with a 25/64" fractional drill (I didn't have a 10mm drill at that time). Then the raised portion of the DA-50 drill guide didn't quite fit into the hole since 25/64" is .390625" and 10mm is .3937". Finally got it all to work after buying a 10mm drill.

Gerry,

I do not disagree with your assesment regarding price. In fact I try to avoid Zingers on my DA50. The biggest problem that I had recently with quality props was just getting one. None of the hobby shops in my area (nearest one is 40 miles) carry anything but Zingers in 20"+. This past spring everytime I called one of the quality prop distributors, they were out of 22x8, 22x10's. I even tried to buy some at Toledo Expo and none were to be found there as well. Though I didn't want to, I was stuck with the Zingers for the early part of the season. I did not let it stop me from flying or let it ruin my day(s). They were good enough to get me by at the time. I guess what I am trying to say is that I think Zingers are on the low end of the performance scale, but I don't think that they are completely worthless either.

Last month I was able to get some NX's (nobody had any Menz which I had been using) and I will give them a whirl next year. I would try them this year, but about 2 weeks ago my CA 27% Extra was "shot down" by another radio.....but that's another story.

Mike

It doesnt make any difference.
When you go to 6 bolt patterns its even harder. I doubt hardly anyone has seen a prop split because of the holes in it!!
I agree with the Zinger/ MAs paint stirring uses but I still use them when I HAVE to because no one carries anything else around here.
You will be pleased when you get a better prop, the new BMEs look good and I have had good luck with NX its the shipping that sucks.