 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
Jerry Cochran
Joined: 10 Jan 2006
Posts: 111
Location: Wilsonville, OR
|
 Posted: Sun Jul 09, 2006 9:12 am Post subject: Fuel economy / was Fossil energy fuel..... |
 |
|
Tracy,
With due respect, Van's tested two more or less identical rotary conversions in the "RV-Ator, 2nd issue of 2005. These were both RV-8's built as "twins" by two friends and retired pilots, Jim Clark and Gerry Gustafson. These were Powersport Rotaries and turned out beautifully. I had the pleasure of viewing them and talking to both men at Van's Homecoming 2004.
The article is quite extensive, as was the testing, but I'll just mention that at cruise with identical speeds, the article states "But, in all cases, even at equal speeds, they burned more fuel than the reciprocation engines." Also... "The rotaries were definitely noiser inside and out." For instance, at cruise Van's RV8 burned 5.05 gals and the two rotaries 7.65 and 7.1 respectively. This was a round trip of 140nm.
So it appears from their data that rotaries, at least these two, burn substantially more fuel. What do you think? I don't have a scanner, but would be happy to fax or mail copies.
Jerry Cochran
Wilsonville, OR
| Quote: | From: "Tracy Crook" <lors01(at)msn.com>
Subject: Re: RV-List:Fuel economy / was Fossil energy fuel.....
That was seriously Cool data Dan.
Thanks also to Ed Bundy who supplied his numbers. It is surprisingly
hard to find RV drivers who keep track of this stuff (too busy having
fun in these things which I also understand : )
be a significant advantage. If you ever get the chance Dan, I'd like
to see you do the same test but instead of dropping manifold pressure
only, try dropping the prop rpm to get the same fuel flow numbers you
used. This should reduce pumping losses and result in even better
numbers. "Do not operate" zones on the prop rpm is the only possible
problem I can think of. I don't have that problem with my fixed pitch
wood prop but I have to put up with very high pumping losses, especially
at low altitude (which is another reason I cruise high).
Bottom line is that based on this info, I don't see a nickel's worth of
difference between the Lyc (when run LOP) and my Mazda rotary when it
comes to fuel economy. Cleanliness of the airframe makes more
difference than the engine. I always burn less fuel than the guys who
run Lycs ROP.
The horror stories about the fuel consumption of the rotary are based on
automotive experience. Ironically, the rotary is at it's worst in auto
use. The lower the engine load, the worse the rotary is. Car's
typically run at 10% or less power settings. At low power settings the
flame goes out in the large quench areas of the rotary combustion
chamber resulting in more unburned mixture. The higher the power load
is, the longer the flame stays lit and more complete combustion results.
The crumby results on the rotary RV-8 comparisons they did at Van's home
drome were the results of two factors.
1. The fixed prop RPM rule put the rotaries at a disadvantage. They
should have allowed the pilots to set it at best economy for the two
engine types (it is not the same).
2. The EFI controllers used with the Powersport engines do not allow
the pilot to optimize the mixture. They were essentially running at
full rich the whole time. The designers of it did not consider the
users capable of deciding this and programmed what they thought was the
safest mixture setting (rich).
Tracy Crook |
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
 |
lors01(at)msn.com
Guest
|
| Posted: Sun Jul 09, 2006 3:01 pm Post subject: Fuel economy / was Fossil energy fuel..... |
|
|
<?xml:namespace prefix="v" /><?xml:namespace prefix="o" /><![endif]--> Hi Jerry,
I've read the articles (those were the planes I was referring to) and do not dispute the results at all, as I said, the rotaries had 'crumby' results. I only offered the reasons why I believe these two rotary powered planes did so poorly on the tests. My RV-4 is not nearly as clean (aerodynamically due to fit and finish) as those beautiful RV-8s but I get significantly better fuel economy when I try to duplicate those test conditions. I don't have a CS prop so can't do it perfectly. The main difference is, I have full control of mixture and they do not.
As far as the noise issue, both of the RV-8s now have an improved muffler system since that test was done and are much quieter. Ask Jim & Gerry about that for details.
Tracy Crook
[quote] ---
| | - The Matronics RV-List Email Forum - | | | Use the List Feature Navigator to browse the many List utilities available such as the Email Subscriptions page, Archive Search & Download, 7-Day Browse, Chat, FAQ, Photoshare, and much more:
http://www.matronics.com/Navigator?RV-List |
|
|
|
| Back to top |
|
|
|
|
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum
You cannot attach files in this forum
You can download files in this forum
|
Powered by phpBB © 2001, 2005 phpBB Group
|
Get Email Distribution Too!
FAQ
Search
Memberlist
Usergroups
Register
Profile
Log in to check your private messages
Log in
