Hello and is this a stupid question

Airboat propeller discussion.
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determined
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Hello and is this a stupid question

Post by determined »

Hello from the Great White North. :canada:
Well Northern Saskatchewan anyways.
Just found this site and I am amazed at how much info is on here relating to my project.
What I am working on is an early 1940's Fudge snowplane [think airboat on skis]
I have a vintage prop 68'' 28 pitch that I would like to use but it is drilled 6 bolt.
My machine has a Franklin 150 aircraft engine on it which has an 8 bolt hub.
Is is acceptable to plug and redrill the bolt pattern? Or is this a big no no?
I am open to suggestions.
I installed an Ivoprop on a rescue airboat 10-12 years ago and it was a nice system to work with, but my preference goes to wood for original appearance.
Not sure if any of your outfits use an 8 bolt hub but it would be nice to hear what is out there and what is available that would work on my project new or used.
Thanks Dave
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Snowplane Paint Job 032.jpg
swamper2
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Re: Hello and is this a stupid question

Post by swamper2 »

don't think that is enough prop for that motor. what is the rated hp/rpm for that motor.
16ft alumitech/406sbc/2.38w/3-80in.R's
determined
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Re: Hello and is this a stupid question

Post by determined »

Engine specs are 150 hp at 2600 rpm.
Priority goes to power to get it moving with 4 people inside and skis half frozen to the ground.
Top speed is less of a concern as these machines often were fitted with a 40 hp car engine back in the 40's and moved along fine once they got going.
Speed is limited by snow/ice conditions as well the vintage suspension on it so ideally I need something that will push hard without over reving the timber to bits and pieces.
With this info what would your thoughts be for length and pitch?
With the existing cage the most I could comfortably fit would be a 72'' prop.
Dave
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pipedog
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Re: Hello and is this a stupid question

Post by pipedog »

Looks like a cool build! My first thought is not to use a old prop, unless it is reconditioned!!! As swamper said if it is not enough prop it can over rev. I know there are some boats around with the franklin motors maybe someone can chime in with prop size and bolt pattern. Maybe start a new post with a title "Prop for Franklin". Good luck on the build and post up pic's as you go!!
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:)
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Re: Hello and is this a stupid question

Post by :) »

Do not fill in holes and redrill! I don't know y u couldn't look at a carbon fiber adjustable pitch prop? U can find them relatively cheap in our classified section.
14 ft Combee. 4 seater, BPE 383 sb chevy, 2.09 stinger, 3 blade ww stump puller.
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gblack15
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Re: Hello and is this a stupid question

Post by gblack15 »

We have a handful of wood prop suppliers that can customs fit a prop for you. Search the site I'm sure you will find what you need. Don't forget to check the classifieds and supplier sections
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goldhunter_2
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Re: Hello and is this a stupid question

Post by goldhunter_2 »

I agree not enough prop if you have room to fit a 72" I'd definitely do that for the extra push over the shorter prop , on the ice the four person load will not be as big of deal to get it moving as it will be breaking the skis free form the ice (mite try parking on old rubber tires). A used two blade carbon fiber Q or signature would be a good choice but I can understand your wanting the wood for appearance in that case you mite contact Sensenich about a new wooden prop for your bolt pattern. You could send them your old prop to see if it can be reconditioned but would be better buying a new longer woody

also remember if your rated tag says 150hp at 2600rpm then when your spinning a wood prop around 3000 rpm you'll be around 170-180hp
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boobidges
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Re: Hello and is this a stupid question

Post by boobidges »

Go on www.barnstormers.com.look in classieds under piston engines, then to Franklin. Look for classic aire.bruce Kown.extremely knowledgeable on franklins
determined
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Re: Hello and is this a stupid question

Post by determined »

Thanks to everyone for all for the input.
I have learned more about prop's reading this forum the last few days than I have in the past 6 months.
Next to no market up here for pusher prop's so I am lucky to see 1 prop advertised every few month's and usually it is from an airplane and has a clock stuck in it.
The propeller I have has been in the family for more than 50 years.
Hopes and thoughts of using this prop are for sentimental reasons more than anything else.
I will make some calls to some of the prop makers and see what is available.
If anybody knows of a prop drilled for an 8- bolt Franklin pattern please let me know.
Dave
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snowplane.3.jpg
Striker543
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Re: Hello and is this a stupid question

Post by Striker543 »

I understand your desire to use the prop for sentimental reasons, but I would highly advise against it for two reasons: 1) it sounds like the prop is too small for your engine, and over-reving a wood prop, particularly a 50 year old wood prop, is asking for trouble; and, 2) chances are slim that after 50 years that prop is safe to use again without being sent to a manufacturer to refurbish it.

I would hate to hear of your project being ruined after a prop explosion, or worse, someone being hurt by the explosion. Wood props make a mess when they explode. My vote would be you put that prop on the wall where your family can continue to appreciate it and find a used composite prop more suitable to your application.

Good luck with your project!
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Bob in Canada
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Re: Hello and is this a stupid question

Post by Bob in Canada »

I've dealt with Sensenich from up in Canada and they were very helpful . A good company to deal with .
I don't know much about wooden props but I'd much rather have a new composite prop that a 50 year old grenade behind me .
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glades cat
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Re: Hello and is this a stupid question

Post by glades cat »

Cool project Dave.
Keep in mind that the prop your snow plane needs is one designed for static thrust. That narrow wooden prop you have looks like an airplane prop and will tend to have a lot of slip until you have forward movement. An airboat prop is designed for high static thrust and would be consistent with your needs. You can find them made of wood and composite material...composite being superior, and they are adjustable. Besides, an exploded wood prop might label you as a Hoser. lol
Water Walker, Sensenich and Whirlwind build what you are looking for and are mighty helpful. You might give them a call, eh?
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determined
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Re: Hello and is this a stupid question

Post by determined »

Contacted Sensenich and gave them the info regarding my snowplane.
The prop they quoted me on was a 68" narrow blade wood 32 or 34 pitch, reasonably priced.
Other option was a 3 blade composite ground adjustable, 2 1/2 times the cost of wood.
Sounds like the composite would be the best way to assure I end up with something I can use but as this machine is 70 + years old the look of a wood prop is much more appropriate.
Feedback from others who have more experience with pitch and diameter would be appreciated.
I would expect the prop they reccomended comes from years of experience so I dont want this to sound like I am second guessing them, this is not my intent.
Sensenich and probably most others have a cash up front no return policy so I dont want to get stuck with an expensive propeller to hang on the wall.
Depending on number of passengers and fuel load machine will be 1000-1500 lbs.
Engine rated at 150 hp at 2600 rpm.
Not building a racing machine, just want good push to get moving.
Dave

Photo is of a 1930's Fudge Snow Sedan
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akblackdawg
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Re: Hello and is this a stupid question

Post by akblackdawg »

There are some dealers in Florida that often have a "loaner" prop for you to try out on your machine. However, even if they did have a loaner for you, shipping back and fourth if it didn't turn out to be one you wanted, would most likely wipe out the cost of a second prop. Sens people are pretty good, take your best guess and go with it, i agree, a pretty natural wood finish prop would go well with that boat. Bud
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swamper2
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Re: Hello and is this a stupid question

Post by swamper2 »

take that woody. You will be happy as long as your engine is up to snuff. 32 pitch
16ft alumitech/406sbc/2.38w/3-80in.R's
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pipedog
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Re: Hello and is this a stupid question

Post by pipedog »

Glad to hear your going with a new prop,stick with the wood :thumbleft: ...I would love to go for a ride :salute:
Palm Beach open hull 13'9" with 6.0 F.I. LS - Ox Box and a 3bld "R"
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