Can you repitch APC props?

[Andrew Tinsley]

The heading sys it all. If you can, what is the best method?

Regards,

Andrew.

[tom brightbill]

Andrew, You might find something in here, good luck:

http://www.bolly.com.au/1998%20Bolly%20Book%20v3.pdf

[Tim Wescott]

I'm so far out of touch it's pitiful.  I didn't realize that Bolly was still in business, and appears to sell props in our sizes.

So, do folks use them still?

[peabody]

Dennis is repitching WOODEN props.......

[qaz049]

I'm so far out of touch it's pitiful.  I didn't realize that Bolly was still in business, and appears to sell props in our sizes.

So, do folks use them still?

You obviously didn't read this bit on their web page. at: http://www.bolly.com.au/

" Carbon Fibre Propellers are available via special order, MOQ = 50 pcs

Wood Propellers are back in production and are only available through our exclusive USA dealer, no MOQ.

Pro Glass (Injection Moulded) Propellers are available via special order, MOQ = 1,000 pcs

Landing Gear and Heli Products have been discontinued. Details will be soon be moved to an "archive" page. "

[Dennis Toth]

Andrew,
Repitching is done with a pitch gauge, heat gun and work gloves. The basic process is to set the pitch gauge at the 70% station to the new pitch you want and lock it there with a small clamp. Next, put on your gloves (these should be heat resistant like leather work gloves) and heat the inner 1/3 of the blade, you need to rotate the prop top to bottom to evenly heat the blade. For IC props you need to heat for 5-7 mins, for electric props heat 3-4 mins each blade. You need to heat soak the blade so heat and let it sit a minute then resume heating.

Once the blade is heated you grab the hub and twist the heated blade in the direction you want the pitch to move. Sometimes you need to do this several times to get the pitch where you want it. The IC props take more heat and a lot of twist force. It takes a few tries but you will develop a feel for how much heat and twist you need to get the blade to move.

BTW, you can also re-pitch wood props the same way.

Best,    DennisT

[Mike Haverly]

The answer to the original question is yes.  It requires more heat, but it can be done.  I'm pretty sure that APC's are inexpensive enough that most folks just buy a different size.  Trimming the tips can decrease their efficiency significantly.

If Dirty Dan is around he can explain how he used cooking oil to accomplish the task.

[Motorman]

I've re-pitched APC props to get something I use to make a mold. It's not something I would recommend for a short strand soft plastic prop. Very easy to cause damage that may or may not be seen. People boldly do it and brag about it but, I've seen what happens to a model that throws a blade in flight so I'll live without it.

MM

[wwwarbird]

 Where's McEntee?

[Howard Rush]

Paul Walker can tell you how to repitch APCs. 

Andrew, You might find something in here, good luck:
http://www.bolly.com.au/1998%20Bolly%20Book%20v3.pdf

I saw a bunch of misinformation about props, but not how to pitch them.

 

So, do folks use them still?

They're good for OS .40 VFs, but require modification opposite of what Bolly says.  The Tg of Bolly's resin is low, so they pitch easily with boiling water.

[Tim Wescott]

You obviously didn't read this bit on their web page. at: http://www.bolly.com.au/

I read it later.  After I'd exposed my ignorance.  That seems to be a pretty common modus operandi for me.

[Brett Buck]

Andrew,
Repitching is done with a pitch gauge, heat gun and work gloves. T

   This is *only* for APCs and similar GRP props. The only reason to use a heat gun is that boiling water takes too long. Otherwise, a heat gun should *never* be used to repitch props. Even Eathers work fine with boiling water. Heat guns get to hot and can cause the resin to break down and it's very difficult to control the point at which the angle change takes place.


   Brett

[Gerald Arana]

I'd be real apprehensive about using "oil" around a high heat source.  Sounds like a very good way to burn down the house....

In the last month and a half or so, I've seen two houses in my neighborhood on fire! Sure would ruin a good building day.

IMHO I don't think anybody flying less than "expert" needs to bother to try to "re-pitch" a prop. Learn to fly better first...Just saying. 

Cheers, Jerry

PS: I'm trying to fly better myself!

[Mike Haverly]

I'd be real apprehensive about using "oil" around a high heat source.   Sounds like a very good way to burn down the house....
In the last month and a half or so, I've seen two houses in my neighborhood on fire! Sure would ruin a good building day.
IMHO I don't think anybody flying less than "expert" needs to bother to try to "re-pitch" a prop. Learn to fly better first...Just saying.  

Cheers, Jerry

PS: I'm trying to fly better myself!

You have never deep fried anything?  No different, same oil, just hotter.  Maybe if more advanced flyers would learn about re-pitching they would improve faster.  Just one more trimming tool, an important one at that.

[Andrew Tinsley]

Thanks everyone,
Especially to Brett for givng some info specific for APC props. It obviously puzzles some people why one would wish to repitch APC props, with such a huge range available. Well I am going to have a go at 4 stroke speed, a new class being proposed in UK. It is really for aged fellows like me that can't get round the pylon fast enough for the "hot stuff"!
APC do some 14 inch pitch props which would work with a 60 four stroke. With the limited revs of said four stokes, then a greater pitch than 14 would be an advantage. Hence the question.

Andrew.

[Brett Buck]

Thanks everyone,
Especially to Brett for givng some info specific for APC props. It obviously puzzles some people why one would wish to repitch APC props, with such a huge range available.

  Just like anything else, you sometimes need to fine-tune. Jim Aron uses an APC 9-4 depitched to 3.6 for his 25LA/Feno. I used an 11.5-4 (original narrow-blade version) depitched to about 3.7 at the 94 NATs. Interestingly, once you do it, it stays. I take that prop out of the bin occasionally and measure it, and it has held for >20 years now.

     There really aren't that many props from APC that are very useful in real stunt with full-size mainstream engines. The 3 intended for stunt were the (long discontinued) 11.5-4 narrow, the current 11.5-4 "medium" (both inspired/directed by Bill Werewage for 40-sized piped engines), and the 12.25-4.25 (on David's instructions, for the 46VF, sort of a bigger 11.5-4). They all still work pretty good for various stunt engines, but it's very difficult to beat the Eather and other graphite or fiberglass/epoxy types for adjustability and performance, not to mention they are much, much lighter than the APCs.

    Brett

[Dennis Toth]

Andrew,
Since you will be flying a speed event you have some options we don't have in Stunt (I've flown speed years ago). You only need to get through one flight per prop, of less then 2 minutes. You might look at some of the APC electric props that you can pitch up to were you need, also look at some of the Carbon Fiber drone props, lastly you could look at some wood props that you can also re-pitch with heat (I like using the heat gun for this, works just like doing the APC's).

Currently wood props available are Zingers - a great prop kit, lots of wood to carve to what you want; Top Flite Power Tips - closer could work better for speed with some thinning and re-pitching; RMS - great stunt prop kinda spoon shape blade maybe not be the one for speed; BY&O Brodak - again spoon shape not the greatest for speed.

Keep us informed how you proceed and post pictures of you ship and prop.

Best,        DennisT

[Allan Perret]

   and the 12.25-4.25 (on David's instructions, for the 46VF, sort of a bigger 11.5-4).

Brett:  Do you know if this prop is still available ?

[Allan Perret]

Currently wood props available are Zingers - a great prop kit,

Dennis:  I have often seen the Zingers refered to as a good "Prop Kit".  Are we talking about the standard Zinger or the Zinger Pro series ?

[Gordon Van Tighem]

eliminatorprops.com
...have info and more.

[Brett Buck]

Brett:  Do you know if this prop is still available ?

  Probably not -because it NEVER EXISTED.  I just got it wrong, the 46VF prop was the 12.25-3.75 that we all know about. As far as I know, that one is still available.

   Brett

[Allan Perret]

  Probably not -because it NEVER EXISTED.  I just got it wrong, the 46VF prop was the 12.25-3.75 that we all know about. As far as I know, that one is still available.

   Brett

Somebody told me the 12.25-3.75 was developed for the RC 3-D hovering crowd.

[Brett Buck]

Somebody told me the 12.25-3.75 was developed for the RC 3-D hovering crowd.

 
    I don't think that David knows anything about RC 3-d hovering!  It might work well for that, but it was originally a bigger/flatter version of the 11.5-4 so it would use the full power of a 46VF (vice a 40VF).

  Fun fact - the APC factory was and maybe still is a few miles from the canonical Fox 15 Hurl site.

    Brett

[Dan McEntee]

   Ted Fancher told the story of the beginnings of the APC 12.25X3.75 prop here on this forum. A simple search should turn it up. Interesting story. I like the prop a lot. Seems to be a "magic prop" that works for a lot of engines like the APC 9-4 and 10-4. It's been a while since I've been on their web site, but they used to have section just on propeller theory that you should read even if you don't use their props.
    All props aren't the same. Put four different brands of 11-4 props on an engine and fly them and they will all perform differently. I haven't been the biggest fan of Zinger props to use right out of the box. Even working them over didn't get me what I wanted when trying them on an ST.60 I tried several different sizes of Zinger Pro props on several different engine/airplane combinations and always found something that worked better. The one exception so far has been on my P-Force that has a Randy Smith tuned OS.32F on it. I tried six or seven different props out of my stash without much improvement in performance until I tried the 11-4 Zinger Pro. That prop really made the engine/airplane combination come alive. I only had two or three, so went to buy more and they were out of stock at most distributors and were on back order for about a year! After really taking care of what I had, they started to trickle in and I got a half dozen more!  I have an old suit case that I store extra props in and some one asked me one time why I had so many props, and I told them some times it takes that many to get what you want!
  Type at you later,
  Dan McEntee

[Brian Massey]

Maybe if more advanced flyers would learn about re-pitching they would improve faster.  Just one more trimming tool, an important one at that.

I've learned to repitch props . . . but I don't seem to be improving faster . . . as a flyer. But I did learn what an amazing trimming tool it is.

Brian

[Dan McEntee]

I've learned to repitch props . . . but I don't seem to be improving faster . . . as a flyer. But I did learn what an amazing trimming tool it is.

Brian

    That's what it's all about! Learning cause and effect. If you go through the motions and do the work, and understand what the results should be, and you can see and feel those results, that adds to your confidence level and you move on. One more tool in your tool box. The hobby might not be as much fun for some of us if you could just buy EVERYTHING you need! A lot of satisfaction in making stuff and modifying things and then they work like they are supposed to.
  Type at you later,
  Dan McEntee