ChuckAuger

My Feedback: (12)

I've been pretty happy with the way the YS .63 has been flying the Sledge with the 13X5 Zinger. Real happy. But it seemed like it would burble a little right in the hover zone..and for a neophyte hoverer like me it was kinda tricky. One of the 3D masters at Houston even mentioned how it had a little catch "right there" but the engine was brand new then and I wasn't too concerned.

So I got some 14X4 Zingers and did a little work on one..sharpened the LE and TE, thinned the airfoil, thinned the tips, swept the tips, left the back alone. These tricks I've picked up here. Well it worked great...turns about 600 more than the stock 14X4, about 400 less than the stock 13X5 I've been running.

But while I was trying it out in the back yard I noticed something...right in the 1/4 ~ 1/3 stick throttle range, the throttle servo was going nuts. This was causing the burble...it wasn't really a burble, but quickly fluctuating throttle settings... I guess a vibration right at that RPM was making the pot wiper jump. Worked smooth at Idle and WOT...the only two settings I usually mess with while running one up. It was a HS-81. I've got a lot of these on throttles and this is the first one that did that, it was new when I built the Sledge.

So I swapped it out...throttle works great again. When I was building this plane I accidently left out one of the center ribs, and the throttle servo is mounted in the center rib. I ran a couple of 1/16" balsa sticks up eack end of the servo cut out, made it stiffer, and I think this must have helped. Too much trouble to only change one thing at a time in true troubleshooting fashion, so it could have been the servo, the mount, or both.

So on to the field..man this re-worked 14X4 wood is sweetness. I only got one flight in after all the servo changing time, but I can do knife edge loops at a lot less throttle, knife edge in general is better. This thing will do some high alpha knife edge!! And the engine sounds great through the entire throttle range. That alone was worth the bother.

And I might not have noticed if not for fooling around with different props.

3Dreaming

My Feedback: (1)

I'm running a trimmed and thinned 14x4 Zinger on my Saito.72 on my Sledge. It works best of all the props I've tried. Sometime for fun put a stock Zinger 14x4 on it, and see if it changes the flight characteristics. On my airplane it flew terrible. It wouldn't track straight, and would roll out of knife edge real bad. Tom

Wh00ps

Interesting...

I had an HS-81 throttle servo go out on my Fazer twice. Same servo. The pot went, and it started jittering after 8 or 10 flights. Sent it in to Hitec, they replaced the pot and sent it back. Reinstalled, 4 or 5 flights later, same problem started coming back. Talked to the guys at Servo City where I bought it from, and they had me send it back to them, and sent me a brand new one. We'll see how this one holds up.

The guy at Hitec said that a possible cause is vibration, as the 81 has a low-tech wiper-arm type pot, whereas most of the other servos have a solid state pot, which are less susceptible to vibration problems.

*shrug*

ChuckAuger

My Feedback: (12)

You can bet I'll be keeping an eye on this one. I have some Dymond DX200 servos that use a Noble pot...if this one goes south I'll slap one of those in it. I'd have to carve a bit to get a std. servo in there, so it'll be a mini of some sort.

3Dreaming...after looking at the stock 14X4 and running it un-modified, I just don't see it going anywhere but to the belt sander. I like the modified one a lot, and it's not that much trouble to make another one just like the other one.

Wh00ps..what engine were you running? This is the only 4 stroke I have a 81 one at the moment, might be the 4 banging doing it in..

Wh00ps

I've got a GMS .47 on the Fazer. Strong little engine. Pulls at least as well as a 46FX.

The guy at Hitec recommended the HS-85 for a high-vibration environment, and it's a drop-in replacement for the 81. About $5 more, solid state pot and top BB.

ChuckAuger

My Feedback: (12)

Yeah, the better pot is why I save the 81's for non-flying service, I use 85's on flying surfaces. All my 85's are in service (or will be shortly!). Not many people use the little Dymond servos, but I've used them on the ail/ele on some Webra .32 powered (read FAST) 2.5lb combat planes, never a failure except from contact. Not as well distributed as Hitec..you have to get servo gears direct from them, so I'll prodadly end up cycling them into throttle service.

daven

My Feedback: (1)

I would also suggest going to the BB HS-85 for the throttle servo. I had quite a few of the 81s go bad on the throttles of my racers. Problem has gone away since I switched to the 85.

T Smith

Question for ChuckAuger
Hate to change the subject but I wanted to know if you use the 85's on your sledge? And if so any problems? Just curious, cause I'm still in the process of building mine and looking for weight savings.

ChuckAuger

My Feedback: (12)

No problem T Smith!

Like I said..HS-81 on throttle. Everything else are Futaba 9252. They are standard size/weight. I don't know that I would try to save weight with mini servos unless you don't plan on any wild stuff.

The flying surfaces I do use 85's on are on smaller/lighter planes.

T Smith

Chuck thanks for the clarification. Guess I wont be using any minis Well back to the drawing board.

Maj. Crash

In an effort to save a few more grams of weight , I recently started using sub-micro servos for throttle . The first one didn't last very long before it started acting erratically . I was still using braided bronze cable at the time , as I had been for many years with micro servos . I came to the conclusion that the cable was transmitting vibration the sub-micro couldn't handle . I've since switched to trimmer line [weed wacker] , which so far , has worked OK . At the same time I switched to Max servos , I know they're all made by the same people , I just think that different components are specified by different customers .
This is all just my opinion , I hope it helps someone .

Have Fun
Maj. Crash

edberry22

What about some before and after photos of these props so us less knowledgable can see what was done and how?

I for one would like to see that.

ShempHoward

My Feedback: (3)

Chuck - Try an APC 14X4W on that YS 63. Its comparable to the funfly 12.25X3.75 prop for 45-50 size 2 strokes. It will give you that "Hoverin' Fool" sensation.

BTW - My HS81 throttle servo on my now defunct Battle Floyd also started to jitter after ahwile but this would occur only on the first flight of the day. I thought it was either due to fuel residue getting into the case or the wire coming out of the case making a very sharp bend.

ChuckAuger

My Feedback: (12)

Yeah, I have the 14X4W APC..I wanted a light, fast spooling prop that would give the same thrust. This is why I started working the 14X4 Zinger over. I'm happy with the results , but I still have only that one flight on it. That is the burden I bear for living in the Texas Panhandle in the Spring..40 mph wind practically every day. It was yesterday, it will be today, and there is a fun-fly I really want to go to tomorrow...and the forcast is for wind. If they say wind, it will be 30+..anything else doesn't even get mentioned.

ecajberry..I'll try to slap them on the scanner, but I don't know that it will show much detail. Do a search for user name "ceandra" in this forum and you will find a post by him detailing exactly the same method I use. He doesn't have many posts, so you won't have to wade thru a bunch of stuff.

T Smith

Chuck
could you point me in the direction where to find info for reworking wood props am also using ys 63 put it on my topcap
w/apc 13x4w,14x4w just looking for that little extra. thanks

ChuckAuger

My Feedback: (12)

1. Sharpen the tip. Just touch it to the belt parallel to the tip, cuttin in about 3/8" from the tip, on the top of the airfoil. Could do this at the field with a sanding block. Just get the very tip razor thin. In fact, this one mod will do more than anything else, and you could quit here.
2. Sharpen LE. Straight sand back to high point (or just in front of high point).
3. Sharpen TE. Straight sand forward to just behind high point. This should leave about 1/8" unsanded at the high point, so that you still have that for reference.
4. Knock down high point. Rock the blade while pressing on the sander, in order to restore a rounded shape. Try not to move the high point much. I like to use the belt just below the top roller, where ther is no backing board, so that the belt will deflect into a curve.
5. Final balance and sand with 180 to 220 grid by hand.
6. Paint if you want, but you're just going to break it. I use clear dope spray.

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That is pretty much what I do. If you look at a Zinger wood prop, the LE and TE are both just FLAT! Like 1/16" or so..sharpen them to a sharp edge. This is easy. DO it from the FRONT..you don't want to fool with the flat rear face of the prop (and some prop purists will no doubt point out that the rear of the prop is actually the front..I call the part that faces the back of the plane "the rear"..confused yet?? LOL))

The wood prop is THICK! Thin it down some, but try not to change the basic airfoil shape. This sounds intimidating, but it's not. The varnish will be your guide at first. After you have worked it over to the point where all varnish is gone, take a black Magic Marker and paint the high point of the airfoil..this will give you reference when removing wood in this area. Also, think about this..when you sharpen the LE and TE, the untouched high point gets higher, relatively speaking. Knock that sucker back down.

The tips..I just knock the LE down to where it looks more like a APC ..just not square like a Zinger..does it do any good?? Don't ask me, I didn't run it after every step. Also the thinning..now I can see where that would do some good. I thin mine.

So whip out that belt sander (the only tool really suited for the Job IMHO) and give it a whirl.

hroachen

This one started life as a 12*4 Zinger. I knew there was a nice prop hiding in there, just had to find him.

3Dreaming

My Feedback: (1)

I remember from my A&P school days that the back is in front, and the face is in back. The teacher used to drill one of the other students on this. On the props that i've done they look very similar to the ones in the previous post. When I thin my blades I change the camber of the blade some, and I will thin the rear of the blade on the trailing edge. I'm using this set up on my Saito .72 with a 14x4, my HP.40 with a 11x4, and the 11x4 on a Webra .32 all with good results. I've tried other sizes on other engines with not so good of results. Tom

ChuckAuger

My Feedback: (12)

Thanks for backing me up on the front/back of props, Tom..it is more than a little confusing. I was always afraid of messing with the airfoiled side, then I got a prop pitch gauge and found out the only time you want to mess with "the side facing the engine" is to alter the pitch. Since then I've been happily sanding away at props.