do you think i could move up a prop size? - RCCanada - Canada Radio Controlled Hobby Forum
RCCanada - Canada's Radio Control Hobby Forum
Engines Discuss engines

Closed Thread
Thread Tools Display Modes
Old 04-30-2004, 09:42 PM   #1
salty morgan
RCC Contributor
salty morgan's Avatar
Join Date: Sep 2003
Location: shilo, mb

Feedback: 0 / 0%
Posts: 267
Total Props: 0
do you think i could move up a prop size?

       Remove this ad - become a site supporter!
i tied down and sparked up my pitts special tonight, it has a OS 40SF. i checked the tach and with an apc 10-6, it went to 15,000 rpm. do you think i could use an 11-5 or 11-6.

and do you think the extra diameter on the prop might pull it better (faster). if a longer prop has better vertical performance, wouldn't it still be true for pulling a draggy biplane horizontally?

i guess i should expect lower rpm from larger props, but....

i have a theory that i haven't asked anyone about yet. if my 10-6 prop is pulling my plane at a given rpm for a given speed, but a larger diameter prop could pull a draggy biplane faster, then wouldn't the engine get a chance to wind out a bit more. produce more rpm than the smaller diameter prop, because the prop has unloaded a little more.

i was going to tach my zinger 11-5 and 11-7 props, and what ever else i have laying around, but my fingers were too cold from the prop wash!

sure was nice to smell the exhaust again, this was my first startup this year.

i do like to buy other peoples junk...

Bob the Builder is my pilot.

i wish i were more gruntled.

ch 41
salty morgan is offline   Quick reply to this message.

Sponsored Links - Subscribe to remove this ad.
Old 04-30-2004, 10:21 PM   #2
RCC Senior Contributor
treecutter's Avatar
I am: Chris l
Join Date: Apr 2003
Location: Regina, Sk Canada

Feedback: 3 / 100%
Posts: 551
Total Props: 0
ahhhh the age-old pitch vs diameter arguement....well here's my explanation....diameter=thrust and pitch=speed, if you want better SUSTAINABLE verticle you have to increase the diameter and decrease the pitch to maintain rpm ie, 10x6 vs 11x5 both props place roughly the same load on the engine and will give you simular RPM's but the 11x5 will pull the airplane harder as the 10x6 will move it along faster. I think you should try a 11x5 and see what you think. BTW 15k rpm out of an SF with a 10x6 is great! I think you could even go to a 11x6 and be happy with the speed there, try out a couple different props, they are cheap and its fun to experiment.
treecutter is offline   Quick reply to this message.
Old 05-01-2004, 12:38 AM   #3
Ed Smith

Feedback: / %
Posts: n/a
Total Props: 0
try out a couple different props, they are cheap and its fun to experiment.
Ain,t that the truth.

I pylon race. we are endlessly searching for "The prop". We have all read the theory and there is plenty to go round, good and bad. In the end we all do the same thing. We stick a prop on the airplane and see what happens in real life. Usualy the theory is shown to be just that.

Ed S
  Quick reply to this message.
Old 05-01-2004, 11:50 AM   #4
RCC Supreme Contributor
AJCoholic's Avatar
I am: Andrew Coholic
Join Date: Sep 2002
Location: Timmins, Northern Ontario
Radio of choice:
JR 12X

Feedback: 5 / 100%
Posts: 9,873
Total Props: 1
On a .40 size engine, I would try an APC 11-4 and an 11-5. I routinely use the 11-5 for flying sport aerobatic models and the 11-4 is my prop pf choice for anything like a profile fun fly, that I like to hover a lot.

The 11-4 loads the engine allmost the same in my experience as the 10-6 as for top rpm. Give it a try, for $4 if you dont like it what have you lost?
Andrew Coholic -MAAC #26287L

1/2A to giant scale, IMAC, SAM, R/C sport, turbine jets, Heli's...
if its got a wing or two and an engine - I like it!
AJCoholic is offline   Quick reply to this message.
Old 05-01-2004, 11:58 AM   #5
RCC Supreme Contributor
nony's Avatar
Join Date: Sep 2002
Location: the Park, Ab.

Feedback: 0 / 0%
Posts: 4,339
Total Props: 0
that is part of the fun of this hobby..spend a few bucks on a prop and see if it makes a difference. I got 3 of those Pringles cans full of different size props ...

If you got deep pockets, try a 4 blade APC would probably look silly on a Pitts, but it sure does wind up, and keeps the revs in the verticle.

My all time favourite is the 3 blade Tornado...big fat blades gave all kinds of thrust.....over time, mine all got broke (somehow ) and they are no longer made as far as I know...........

The sooner you fall behind, the more time you will have to catch up.
nony is offline   Quick reply to this message.
Closed Thread

Quick Reply

Register Now

In order to be able to post messages on the RCCanada - Canada Radio Controlled Hobby Forum forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

Member names may only be composed of alpha-numeric characters. (A-Z and 0-9)

!!ATTENTION ADVERTISERS!! If you intend on advertising anything on this forum, whatsoever, you are required to first contact us here . Additionally, we do NOT allow BUSINESS NAMES unless you are an Authorized Vendor. If you own a business, and want to do sales on this site via posting or private message, you will need to follow the rules. Shops, Stores, Distributors, Group Buys without being authorized will see your account terminated.
User Name:
Please enter a password for your user account. Note that passwords are case-sensitive.
Confirm Password:
Email Address
Please enter a valid email address for yourself.
Email Address:
Your Name
Your first name and last initial is required if you plan on using the forum.
Which city & province you live in. This is mandatory for classified listings.
Radio of choice?
Which radio is your current favorite to use?
Number of RC Vehicles?
How many boats, cars, planes do you own?


Human Verification

In order to verify that you are a human and not a spam bot, please enter the answer into the following box below based on the instructions contained in the graphic.

Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
vBulletin Message

Thread Tools
Display Modes

Forum Jump

All times are GMT -5. The time now is 08:45 AM.

vBulletin Security provided by vBSecurity v2.2.2 (Pro) - vBulletin Mods & Addons Copyright © 2016 DragonByte Technologies Ltd.