Topic: Controllable Pitch propellers (Read 11858 times)

kiwimodeller · « **on:** July 04, 2010, 10:27:36 am »

Very nice as usual Nic, just dont forget those variable pitch props though. Cheers, Ian.

HS93 (RIP) · « **Reply #1 on:** July 04, 2010, 10:37:06 am »

kiwimodeller did you ever sort the variable pitch props out you had .?

peter

kiwimodeller · « **Reply #2 on:** July 05, 2010, 10:49:32 am »

I have one fitted in a 900mm River Queen open launch driven by a Gage single cylinder from Graham Industries. See my post
http://www.modelboatmayhem.co.uk/forum/index.php?topic=24071.msg238082#msg238082 I have not completed the model yet but have had it in the water once for test purposes. The prop appears to work really well. There was ample thrust forward and reverse and yet it did not stall the engine even if I put it to full pitch while the engine was running at low revs. The lever controlling pitch was so easy to move that I have changed from my original plan of having the operating lever vertical over the prop shaft and operated by a full size servo. Instead I have laid the lever on its side and connected it to a micro servo which means the whole lot can be hidden under the floorboards. I was working on it again tonight and hope to have it ready to test sail in a couple of weeks or so. Will post the results when it is running. Cheers, Ian.

Bernhard · « **Reply #3 on:** July 05, 2010, 10:58:10 am »

hi.............what size is the your prop.............i use 4 blade 60mm on the River Queen i have..............

Regards Bernhard

kiwimodeller · « **Reply #4 on:** July 06, 2010, 11:09:00 am »

Berhnard, the variable prop I have is 3 blade and 55mm diameter. According to the information I found about it on full ahead the pitch is 1.25 times the diameter. So far it seems to suit the little Graham Industries single cylinder engine very well but I have only tried it with the boat tied up. I am working on installing the servos now and hope to do a test sail in a couple of weeks but it is mid - winter here now so I might have to wait for a nice day. Cheers, Ian

derekwarner · « **Reply #5 on:** July 06, 2010, 11:59:52 am »

mmmm.

pitch...Ian not sure here, but if a 55 mm diameter prop had a 1.0:1.0 ratio it would be SQUARE @ 55 mm envelope depth in pitch & appearing as a 45 degree blade angle

So a 55 mm diameter prop with a 1.25:1.0 ratio would have an envelope depth of 68.75 mm

So I assume 45 degrees x 1.25 = 56.25....

or 90.0 - 56.25 = 33.75 degrees ...is this not a racing angle?

I have enough trouble with my paddle wheel calculations.......

- Derek

gondolier88 · « **Reply #6 on:** July 06, 2010, 01:03:32 pm »

Could one of you guys start a thread on VPP's- you all seem to know a lot more than most about them and I for one am very interested- the title of this thread gives no clue to to the interesting secondary info' on VPP's residing within it.

Thanks,

Greg

Bunkerbarge · « **Reply #7 on:** July 06, 2010, 01:50:28 pm »

Topic split to further the conversation on Controllable Pitch Propellers

Bunkerbarge · « **Reply #8 on:** July 06, 2010, 01:56:45 pm »

just a little interesting point here a propeller with rotating blades should be correctly referred to as a Controllable Pitch Propeller or CPP. All propeller blades technically have variable pitch as the pitch changes in the blade as the distance from the centre line increases.

Before anyone says anything I know quite a few real ships incorectly using the term VPP as well!!

gondolier88 · « **Reply #9 on:** July 06, 2010, 06:25:16 pm »

Thanks BB,

I wonder if anyone here has built one and could expand on the workings- as I understand it they are supposed to fairly simple- but I can't see it myself?

Greg

MONAHAN STEAM MODELS · « **Reply #10 on:** July 07, 2010, 07:27:26 am »

Greg,

I've built a few of them. They are fairly basic and not hard to build if you have access to the proper tools. If I can remember to grab the camera on my way out the door to the shop, I'll take some photo's and post them however if anyone else has photos post them cause I'm notorious for forgetting the camera.

HS93 (RIP) · « **Reply #11 on:** July 07, 2010, 07:55:02 am »

you may get some ideas from these i have a couple I can photograph if needed, they tend to be a bit bulky and large but ok for a 30" plus sized boat

http://www.modelboatmayhem.co.uk/forum/index.php?topic=18113.0

http://www.modelboatmayhem.co.uk/forum/index.php?topic=16377.0

Peter

kiwimodeller · « **Reply #12 on:** July 07, 2010, 09:46:02 am »

I have seen a couple of magazine articles on how to build them but have not attempted it as I do not have the machining facilities or the expertise. The two I have are a three balde WADA made (from memory) by the Yokohama Model Co and a four blade Raebosch as shown in the drawing above. I have an advert from a 1980's mag where the Wada is advertised by Maxwell Hemmens. I have not yet given either a proper test but have always thought they were a very good solution for non - reversing engines. I will certainly post results as soon as I do some test sailing. The WADA is quite compact and lightly built but seems ideal in the River Queen with the Graham single. The Raebosch on the other hand is very substantial. It came without blades and I would love to find a set if anybody knows of a source but I have made up a set to try. It did come with four slotted head screws in the hub and I have made blades and soldered them in to the slots. At the moment the diameter is 90mm and even that does not look in proportion so I presume that originally it was around 100mm. I have also seen a smaller three blade Raebosch which was the same design of hub but to a smaller scale. I guess it was about 70mm. I look forward to hearing iof others experience with them and hope we can prod Nick in to making some available again. Cheers, Ian.

derekwarner · « **Reply #13 on:** July 07, 2010, 11:00:16 am »

Hi all .....& Ian....I do not want to spread dirty water

on a semi hallowed subject....

...but in essenencce

1. VPP or CPP = the principal use of with economies with a constant speed engine

2. gas turbine engines ....themselves

this application [as they love constant speed/differing load conditions]

Having said this

...with the the inherent complexities ......not sure why anyone would want or need a model CPP.........

...

why not try ....danielbourard.??? ......I will come back with the correct WEB address......Derek

HS93 (RIP) · « **Reply #14 on:** July 07, 2010, 02:06:13 pm »

Quote from: derekwarner_decoy on July 07, 2010, 11:00:16 am

Hi all .....& Ian....I do not want to spread dirty water on a semi hallowed subject.... ...but in essenencce

1. VPP or CPP = the principal use of with economies with a constant speed engine

2. gas turbine engines ....themselves this application [as they love constant speed/differing load conditions]

Having said this ...with the the inherent complexities ......not sure why anyone would want or need a model CPP......... ...

why not try ....danielbourard.??? ......I will come back with the correct WEB address......Derek

Try reading kiwimodeller reply and then you will know why some people use them..

Peter

mogogear · « **Reply #15 on:** July 07, 2010, 07:25:09 pm »

This was such a fascinating subject to me a while back that i found a new / old stock Marx Vario 50 CPP in France...The Stirling boat project I was wanting to use it for never materialized...

( The picture shows two boxes)

FWIW- I will never use it...as the name states it has a 50mm diameter blade( although it is 3 separate blades)...the total shaft length is 12" Servo actuated...I have thrown it in the for sales section on RC Groups a while back but it is not even know or looked for much..unused or installed.

Rare? I do not know but not common...Has 3 bearings throughout..if it is of any interest to anyone let me know....Making one is so far beyond me that it is not funny..So I will still follow the designs shown with the same curiosity that led me to my acquisition originally...

cheers

steamboatmodel · « **Reply #16 on:** July 07, 2010, 09:40:01 pm »

Hi Mo,
Do you have one or two of them and what price range?
Regards,
Gerald.

mogogear · « **Reply #17 on:** July 08, 2010, 01:21:50 am »

Quote from: steamboatmodel on July 07, 2010, 09:40:01 pm

Hi Mo,
Do you have one or two of them and what price range?
Regards,
Gerald.

Just one Gerald....Trying to get out of it for what I paid...don't faint..$150 US..

on a given day they can start bidding wars on eBay...I am just not in the mood to fish there until a war happens

steamboatmodel · « **Reply #18 on:** July 08, 2010, 12:15:36 pm »

I didn't faint, just said Dang. I sold one five years back for $75 CAN. now wishing I had keep it. I do know of a place that has the ones with the electric motor going for $125 CAN. but any of the models I would want to put one in I would have to modify the unit. I think I will have to try to build one.
Regards,
Gerald.

Bunkerbarge · « **Reply #19 on:** July 08, 2010, 10:48:56 pm »

I had one of those units after a good friend of mine gave it to me in a clearout. A guy at the club I am in was playing around with the idea of reversing his steam engine so I gave it to him. I was glad it went to someone who was going to get some use out of it.

The idea of paying $150.00 is a bit beyond me.

mogogear · « **Reply #20 on:** July 09, 2010, 05:56:01 pm »

BB--it was beyond me too!! The basic cost of the unit was not that high , but once I bought it through a friend in France ..the shipping was stupid for something so light and small to get to me here in the states.

I could take a loss on it ..wont be the first time in the world of steam I have done that

america12mj · « **Reply #21 on:** July 09, 2010, 07:30:16 pm »

Posts: 1

View Profile Email Personal Message (Online)


Re: Variable pitch prop
« Reply #27 on: Today at 07:26:13 PM »
   Reply with quote Modify message
:-)hy guy
i live in france and a read all the days you'r forum, it's great
about the variable pitch propellers, a very famous french builder make himself a variable pitch propellers , you can see the making off of it at this adress:

http://cnavale.quennetier.free.fr/spip.php?article17

regards
pascal from Paris

benjaml1 · « **Reply #22 on:** July 09, 2010, 11:25:07 pm »

Thank you Pascal....

News:

Author Topic: Controllable Pitch propellers (Read 11858 times)

Bernhard

MONAHAN STEAM MODELS

mogogear

steamboatmodel

mogogear

steamboatmodel

mogogear

america12mj

benjaml1