Go Back  RCU Forums > RC Airplanes > Profile and Fun Flying Planes
 ok couple of thrust / burrito / newbie ?'s >

ok couple of thrust / burrito / newbie ?'s

Notices
Profile and Fun Flying Planes If you're a profile fan or into fun flyers than this is the forum to discuss those topics.

ok couple of thrust / burrito / newbie ?'s

Old 08-17-2004, 03:41 AM
  #1  
Senior Member
Thread Starter
My Feedback: (1)
 
Join Date: Apr 2003
Location: Flagstaff, AZ
Posts: 268
Likes: 0
Received 0 Likes on 0 Posts
Default ok couple of thrust / burrito / newbie ?'s

hey guys

i just got to playing around with thrust HP found at:

http://freespace.virgin.net/barry.hobson/

click the link then under goodies...

ok so
i figured if i tried to simulate my situation i could find out if it will hover ok..

so my variables for me are the following:
air density 23.09 for 7000' where i fly

then i have a tt 46 pro so i figured i would try 2 props a 11.5 x4 (A) and the famous 12.25 x 3.75 (B)

here is my data for that:

at 10,000 RPM:
propA 4.05 lbs of static thrust

prop B 5.21 lbs of static thrust


at 12,000RPM
propA 5.83 lbs of thrust

prop B 7.51 lbs of thrust

do you guys think i can get prop B to spin that quick on that engine with 15% nitro?
if you also factor in wing loading you can geta thrust to weight ratio

and i roughly got 1.3 for prop a sppinning at 12000

and 1.7 for prop B at 12000

what would be my best bet for prop?
how fast do you think the TT 46 PRO will spin the props..

could one of you guys use the program to figure out your situations and let me know what your thrust to weight
ratios are so i can see whether i could pull out of a hover ok etc. etc.
thanks for all the help
-Felix
Old 08-17-2004, 06:46 AM
  #2  
Senior Member
 
Join Date: Apr 2003
Location: Springfield, MO
Posts: 140
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

My TT.46 spins a 12X4 prop @ 12,000. Not sure if it would do that at 7000 feet, but it does at about 800.

rcam
Old 08-17-2004, 07:44 AM
  #3  
Senior Member
 
Join Date: Feb 2003
Location: Omaha, NE
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

Props are cheap. Stop thinking, buy a few and start flying and try em all until you get one that works well. If it's not one that everybody else is using...who cares, as long as it works for you at your altitude. If you struggle getting the power out of that 46, try building a MCP. If you're not handy with the tools, at least get the tower muffler.
Old 08-17-2004, 08:10 AM
  #4  
Senior Member
 
Spastic's Avatar
 
Join Date: Jul 2003
Location: Buffalo, NY
Posts: 441
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

And thats the word of the Quicker..i agree, I've never seen a thrust calculator that was right
build lite, get more nitro
Old 08-17-2004, 08:27 AM
  #5  
Senior Member
My Feedback: (8)
 
Jim D's Avatar
 
Join Date: Dec 2001
Location: Columbia, TN
Posts: 325
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

To chime in with quicker and spastic, forget the thrust calc and try different props. The program is not even close to real world. And there is more to good 3D engine/prop performance than just pure thrust. Airflow over the tail, spool up time, and lots of other issues come into play.

7000 ft is tough. Down close to sea level a 46 two stroke is very capable on a 4-4.5 lb profile. It is marginal on a 4.5-5 lb bird and really not 3D capable after you pass 5lb. Adjusting for altitude, you need to stay light for a 46 to work, very light.
Old 08-17-2004, 12:12 PM
  #6  
Senior Member
My Feedback: (3)
 
wild fred's Avatar
 
Join Date: Nov 2002
Location: , FL
Posts: 1,046
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

or get a saito 72... at 7,000 feet, that's what I'd do! but the burrito comes out pretty light. with the 46 try the 12.25x3.25 or 12-4 apc. if not enough power, get a saito 72 or ys63s... christmas is coming, and they are a great christmas present!
Old 08-17-2004, 12:44 PM
  #7  
Senior Member
Thread Starter
My Feedback: (1)
 
Join Date: Apr 2003
Location: Flagstaff, AZ
Posts: 268
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

haha thanks for the help i will try some different props
Felix
Old 08-17-2004, 01:10 PM
  #8  
Senior Member
 
Join Date: Feb 2003
Location: Omaha, NE
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

Truely, that is the best way, especially since you're about 5,000-6,000 feet higher than most of us

Many like the 12.25x3.75, I don't, but that's just me. My 46's just don't feel "right" when I run them. It may the shizzel for you, though. It's all personnal preferences, with a little help from a Bro [8D]
Old 08-17-2004, 01:12 PM
  #9  
Senior Member
Thread Starter
My Feedback: (1)
 
Join Date: Apr 2003
Location: Flagstaff, AZ
Posts: 268
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

haha thanks quicker..

would a 12x4 spool up a little quicker than a 12.25 ?

and a 11.5x4 will spool up even faster right ?

Felix
Old 08-17-2004, 01:18 PM
  #10  
Senior Member
 
Join Date: Feb 2003
Location: Omaha, NE
Posts: 688
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

I like the 11.5x4. It's my favorite right now. Yes, I find it spools up faster, and that's why I like it.
Old 08-17-2004, 02:10 PM
  #11  
Senior Member
My Feedback: (3)
 
wild fred's Avatar
 
Join Date: Nov 2002
Location: , FL
Posts: 1,046
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

I've been using the 11-5 apc, but I'm at sea level; when I went to cookeville, it seemed a little sluggish, and the guys there were using 12-4's...I shoulda tried one there; a few years back in ky. I preferred the 12-4- so altitude makes a difference!

mainly, keep the plane light; 3 3/4 lbs is not too hard on a burrito; that's what mine weighs with the saito 72. sand it a lot with a big block! at that weight it should still have plenty oomph even at your altitude!
Old 08-18-2004, 04:37 PM
  #12  
Senior Member
My Feedback: (4)
 
SWICK's Avatar
 
Join Date: Feb 2003
Location: vancleave, MS
Posts: 265
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

believe it or not the 12x4 on both my Webra 50 and OS 46 spools up faster than the 11.5x4. The 11.5X4 has a wider blade and cuts more air. I can find the sweet spot with the 12x4 better than the 11.5x4. just my opinion..
Old 08-18-2004, 10:06 PM
  #13  
 
Join Date: Sep 2003
Location: Clifton Springs, NY
Posts: 1,787
Likes: 0
Received 0 Likes on 0 Posts
Default RE: ok couple of thrust / burrito / newbie ?'s

I was running the 12.5x3.75 on my Webra .50 and ran out....I went to a 12x4 and wow what a difference. When the 12.5x3.75 spools up, it's fast, but for 3D you do'nt need that. The 12x4 had instant spool up and the motor seems to run cooler. I am at sea level running 15% nitro, so I would think that the 12"+ wide props would be too much for a .46 at altitude. The Webra is in a 4.25lb burrito and I feel the 12x4 gives me the best control.....

P.S. I break alot of props and the $1.5 savings with the 12x4 vs. 12.5x3.75 per prop makes a difference too.

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are On


Thread Tools
Search this Thread

Contact Us - Manage Preferences Archive - Advertising - Cookie Policy - Privacy Statement - Terms of Service

Copyright © 2024 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.