Extreme Speed Prop Planes Discuss the need for speed with fast prop planes (Screamin Demon, Diamond Dust, Shrikes or any REAL sound breakin'''' plane)

WorldModelsP51/YS91AC/apc11x12

Reply

Old 08-19-2002, 09:34 PM
  #1  
DKjens
Thread Starter
My Feedback: (50)
 
DKjens's Avatar
 
Join Date: Feb 2002
Location: Pasadena, CA
Posts: 2,097
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default WorldModelsP51/YS91AC/apc11x12

I had one of these setups before, but with an apc14x10. It didn't sound fast, but was when flying with other planes. I sold it, but now I bought another. This one, with the apc11x12 is faster I think, I just worry about the engine. My YS91AC turns this prop at 11.3K on the ground, so it may get to 12k in the air. I am wondering for how long this engine will stay together, and I should probably get an apc12x12.
DKjens
DKjens is offline  
Reply With Quote
Old 08-20-2002, 12:18 AM
  #2  
Cyclic Hardover
Senior Member
My Feedback: (3)
 
Cyclic Hardover's Avatar
 
Join Date: May 2002
Location: New Mexico,
Posts: 7,296
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default WorldModelsP51/YS91AC/apc11x12

Here is my WM .40 size P-51. I am running a ST G90 and a Pitts underneath. I started with a 12/8 apc. Went to a 12/10. The magic prop turned out to be a 12/9 apc. I get around 100mph with this and it is smoooooooth. A .91 four stroke would also be very awesome too. The 12/12 or maybe 13/10 would be a good area to start. The one area I was using as a judge on my prop selection was my climb out after a high speed pass. The 12/8 was not problem. So I thought I want more prop and went to a 12/10. Speed was good but climb out was very poor. 12/9 brought it all together.
Attached Thumbnails Click image for larger version

Name:	22176_8393.jpg
Views:	5
Size:	50.8 KB
ID:	13959  
Cyclic Hardover is offline  
Reply With Quote
Old 08-22-2002, 12:30 AM
  #3  
RyanG
Junior Member
My Feedback: (1)
 
Join Date: Mar 2002
Location: Los Angeles
Posts: 27
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default WorldModelsP51/YS91AC/apc11x12

About 10 guys at my field fly 40 size warbirds with ys .91 They are all spinning 13x8 and getting about 12,000 on the ground with ys 20/20 fuel. They clock their planes at about 140 and go up for a split S until you can't see them anymore.
RyanG is offline  
Reply With Quote
Old 08-23-2002, 02:52 AM
  #4  
bugsiegel
Senior Member
My Feedback: (2)
 
Join Date: Dec 2001
Location: brooklyn, NY
Posts: 568
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default 140 mph

can a ys .91 turn 18500 out of a dive
bugsiegel is offline  
Reply With Quote
Old 08-23-2002, 12:36 PM
  #5  
jlong34016
Senior Member
My Feedback: (1)
 
Join Date: Apr 2002
Location: columbus, OR,
Posts: 365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default speed

unless you have clocked or radar gunned a plane these guesses are really meaningless. Everyone thought my DD was really going fast too. Radar gun 115. A trainer was doing 85 at the same time. The smaller the plane the faster it looks.
jlong34016 is offline  
Reply With Quote
Old 08-23-2002, 01:44 PM
  #6  
maverick
Senior Member
My Feedback: (12)
 
Join Date: Nov 2001
Location: Alameda, CA
Posts: 1,575
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Re: speed

Originally posted by jlong34016
unless you have clocked or radar gunned a plane these guesses are really meaningless.
Where do you get the radar gun from? How much are they?
maverick is offline  
Reply With Quote
Old 08-23-2002, 05:56 PM
  #7  
bugsiegel
Senior Member
My Feedback: (2)
 
Join Date: Dec 2001
Location: brooklyn, NY
Posts: 568
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default radar gun

stay away from the 99.00 ebay job. to get any kind of reading off that gun you have to be almost directly in line and real close to the passing plane. way too dangerous. we had one at the club. we wound up putting it back on ebay for a 15.00 loss.
bugsiegel is offline  
Reply With Quote
Old 08-23-2002, 10:30 PM
  #8  
jlong34016
Senior Member
My Feedback: (1)
 
Join Date: Apr 2002
Location: columbus, OR,
Posts: 365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default radar gun

I got mine off the internet. There are many to chose from. I went with an expensive one that reads to 300 mph and has good enough sensitivity so a normal pass down center of runway is easily detected. Mine is from Astro Products. Cost 850.00. But there are several that read to 200 mph for under 200.
jlong34016 is offline  
Reply With Quote
Old 08-23-2002, 10:32 PM
  #9  
jlong34016
Senior Member
My Feedback: (1)
 
Join Date: Apr 2002
Location: columbus, OR,
Posts: 365
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Astro products.

www.astroproducts.net
jlong34016 is offline  
Reply With Quote
Old 08-23-2002, 11:56 PM
  #10  
maverick
Senior Member
My Feedback: (12)
 
Join Date: Nov 2001
Location: Alameda, CA
Posts: 1,575
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default WorldModelsP51/YS91AC/apc11x12

Thanks for the tips on the speed radars guys! It is not something I have ever looked at before so had no idea where to start.
maverick is offline  
Reply With Quote
Old 08-24-2002, 08:16 PM
  #11  
DKjens
Thread Starter
My Feedback: (50)
 
DKjens's Avatar
 
Join Date: Feb 2002
Location: Pasadena, CA
Posts: 2,097
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Update

Bought an apc12x12 yesterday, and flew it today. My YS91AC turned the apc12x12 at 9700 on the ground. It didn't seem as fast in the air, but I feel better (engine health wise) with this prop. With the 12x12 it may unload to 10700 - 11k in the air, with the 11x12 it may unload to 12300 - 12500 in the air, or what do you think. When does valve float start taking place in a YS91AC, and how big is the chance of valves hitting piston top, or other internal no nos?
DKjens
DKjens is offline  
Reply With Quote
Old 10-03-2002, 07:09 PM
  #12  
AeroD79
Senior Member
My Feedback: (2)
 
AeroD79's Avatar
 
Join Date: May 2002
Location: Placentia, CA
Posts: 105
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default WorldModelsP51/YS91AC/apc11x12

WHere did you get your WM ARF mustang from?
Also do you think Saito 100 would do better than YS91?

Btw im the person who I was flying the BLUE mustang at Whittier Narrows...I decided not to move to hawaii ...so im planning to get back my planes together..
AeroD79 is offline  
Reply With Quote
Old 10-03-2002, 07:38 PM
  #13  
BernieG
Senior Member
 
Join Date: Aug 2002
Location: Broken Arrow, OK
Posts: 280
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Re: Update

Originally posted by DKjens
Bought an apc12x12 yesterday, and flew it today. My YS91AC turned the apc12x12 at 9700 on the ground. It didn't seem as fast in the air, but I feel better (engine health wise) with this prop. With the 12x12 it may unload to 10700 - 11k in the air, with the 11x12 it may unload to 12300 - 12500 in the air, or what do you think. When does valve float start taking place in a YS91AC, and how big is the chance of valves hitting piston top, or other internal no nos?
DKjens
You can't evaluate precisely how much an engine "unload" in flight (which is not as much true for a 4 stroke than for a 2 stroke anyway), just as it's very difficult to evaluate how efficient/inefficient a given propeller is. So, for the sake of discussion, let's say both parameters nullify each other. What is interesting, is the comparison. You say your engine reach 11.7 thousands rPm on the ground with a 11*12, and 9.7 thousandd RPM with the 12*12. Let's see: 12 inch per rotation 11300 times a minute => 140400 inches per minute, or 8 424 000 inches per hour, which is 132.95 mph.

Now, the same 12 inches per 9700 => 110.22 mph. Knowing that the wider prop is more efficient than the smaller one, I would bet that a radar reading would read about 100, maybe 105 mph with either prop ! (Airplane drag does not change with the prop...) BTW, this estimation assume an extremely aerodynamically clean airplane....

So I would certainly go for the prop which is the more efficient and is not going to wear your engine too fast.

Bernard
BernieG is offline  
Reply With Quote
Old 10-03-2002, 07:41 PM
  #14  
BernieG
Senior Member
 
Join Date: Aug 2002
Location: Broken Arrow, OK
Posts: 280
Gallery
My Gallery
Models
My Models
Ratings
My Feedback
Default Re: Re: Update

Originally posted by BernieG
BTW, this estimation assume an extremely aerodynamically clean airplane....
What I mean is, just the fact to not have doors to close properly the openings when the gear is up take easily 5 to 8 miles from the top speed ! Those planes ARE NOT aerodynamically clean, all the control horns are exposed to the airflow, etc....

Bernard
BernieG is offline  
Reply With Quote

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


Thread Tools
Search this Thread

Contact Us Archive Advertising Cookie Policy Privacy Statement Terms of Service