Thu Jun 21, 2007 2:51 pm
bdk wrote:Victor or Warren,
What shutter speed are you using for these photos? If Gary is turning 3400 RPM, based upon the prop blur it must be over 1/2500 (if my calculations are correct)????
Calculator mode on:Prop rotation = 75 degrees (guess)/360 degrees = .2083 revs
3400 revs/min * 1 min/60 sec = 567 revs/sec
567 revs/sec * 1/.2083 revs = 1/2722 sec shutter speed
Some are at 1/250 and 1/320. Somehow you have an extra digit in there but remove it and your incredibly close
Warren, excellent shots!
Thu Jun 21, 2007 3:57 pm
Victor Archer wrote:Some are at 1/250 and 1/320. Somehow you have an extra digit in there but remove it and your incredibly close
Rats! You are right... I knew that sounded too fast.
It shows that an engineering degree doesn't make you perfect. 
Prop rotation = 75 degrees (guess)/360 degrees = .2083 revs
3400 revs/min * 1 min/60 sec = 56 point 7 (56.7) revs/sec
56 point 7 (56.7) revs/sec * 1/.2083 revs = 1/272 sec shutter speed
Thu Jun 21, 2007 5:07 pm
An easy count for getting prop blur is :
IF you know the rpm of the engine, you divide it through 60 to have the rounds per second (rps) and multiply this by the number of blades of the propeller.
Example :
If you have 3400 rpm : 60 = 56 rp per second x amount of blades 2 = 112. So you need at least 1/120 sec or slower to have a full turn of the propeller.
If you have 2500 rpm : 60 = 42 rps x 2 blades = 1/80 sec.
If you have 2500 rpm : 60 = 42 rps x 4 blades = 1/160 sec
So if you have a four blades engine you can afford speeds twice as high. The more blades of the propeller, the faster the exposer speed can be. But the slower you can go in the speed/sec the more blur you get.
IF you know the rpm of the engine, you divide it through 60 to have the rounds per second (rps) and multiply this by the number of blades of the propeller.
Example :
If you have 3400 rpm : 60 = 56 rp per second x amount of blades 2 = 112. So you need at least 1/120 sec or slower to have a full turn of the propeller.
If you have 2500 rpm : 60 = 42 rps x 2 blades = 1/80 sec.
If you have 2500 rpm : 60 = 42 rps x 4 blades = 1/160 sec
So if you have a four blades engine you can afford speeds twice as high. The more blades of the propeller, the faster the exposer speed can be. But the slower you can go in the speed/sec the more blur you get.
Thu Jun 21, 2007 9:11 pm
Don't forget though that most warbirds larger than a T-6 have geared nosecases so the props turn slower than the engine.
Thu Jun 21, 2007 11:06 pm
There's to much math being tossed around here. Can we just go back to the pictures and small words so I can keep up.
Nice pics by the way, will look good on Gary's "I Love me Wall".
Nice pics by the way, will look good on Gary's "I Love me Wall".
Fri Jun 22, 2007 3:49 am
Gary, better late than never... I just finished reading your posting.
Congratulations! I can only imagine how thrilling it must have been for you!
I have covered the routes you flew, but on the ground, and yes, the scenery is awesome!
Nice writing, great story telling!
Saludos,
Tulio
Congratulations! I can only imagine how thrilling it must have been for you!
I have covered the routes you flew, but on the ground, and yes, the scenery is awesome!
Nice writing, great story telling!
Saludos,
Tulio
Mon Jun 25, 2007 8:24 pm
So, Gary...
How fast is the little bird at the top end?
How about cruise speed and RPM?
I'm very curious to hear what a <seemingly> stock Cassut can do...
What, if any mods do you have planned before this fall, and what sources are there for information on how to tune an 0-200 to really perform in race trim?
How fast is the little bird at the top end?
How about cruise speed and RPM?
I'm very curious to hear what a <seemingly> stock Cassut can do...
What, if any mods do you have planned before this fall, and what sources are there for information on how to tune an 0-200 to really perform in race trim?
Tue Jun 26, 2007 3:55 am
Kyleb wrote:So, Gary...
How fast is the little bird at the top end?
How about cruise speed and RPM?
I'm very curious to hear what a <seemingly> stock Cassut can do...
What, if any mods do you have planned before this fall, and what sources are there for information on how to tune an 0-200 to really perform in race trim?
Well, I'll try to answer each question in order here...
We timed one of the laps I flew and according to one of the fancy little conversion charts that someone had, it said the little airplane flew an average speed of 194. Not very fast, indeed.
My cruise speed and RPM depends on how stinkin' tired I am and how quickly I want to get out of the airplane. But if I cruise around 3,000 RPM, it typically gives me between 160 and 170 mph (I flight plan for 160).
While at the Pylon Racing Seminar, I was gung-ho to do all kinds of neat little tricks and such to make this little booger go as fast as humanly possible. However, my mentor and former racer, Dusty Dowd, brought some reality back to me by telling me to just enjoy this first year and to remember the reasons I'm racing......1. Because it's a lifelong dream of mine. 2. To recognize my opportunity to be a part of the history of the sport. 3. To recognize my opportunity to be a part of the history of this particular airplane. And he's right. Now don't get me wrong, I'm not saying that I won't do some tinkering here and there to do the best I can while at Reno. After all, it is a race, and I can tend to be a bit competitive. However, I won't be spending every waking moment trying to modify and improve the airplane just so I can win the Bronze race. I think that would distract me from my real reasons for being there.
Either way, I can assure you that I will be having the time of my life.
Gary
Wed Jun 27, 2007 4:53 pm
Looks like great fun!
Super glad you made your trip out and back with no problems.
Good Luck in September!
Z
Super glad you made your trip out and back with no problems.
Good Luck in September!
Z