 |
Matronics Email Lists
Web Forum Interface to the Matronics Email Lists
|
| View previous topic :: View next topic |
| Author |
Message |
cjhukill(at)cox.net
Guest
|
 Posted: Tue Aug 26, 2014 4:28 am Post subject: FAB wars |
 |
|
Glad I could help with the FAB wars. I appreciate the comments and would to respond to few. The three holes in the back are mathematically the same area as the intake throat of the injection servo, so if the reeds are fully open, the airflow would be the same as a hole in the bottom of the airbox with Vans system. I doubt that Vans did any engineering on the size of the filter area, as it’s the same filter they use for all the engine sizes. Off the shelf stuff. The proof is in the pudding. On my RV8, with a souped up AEIO 360, and the same filter, the loss is 10%, determined by actual tests. I attributed that loss to the loss of ram effect, not filter area. The same actual test will be done in my first 25 hours, and I will post results. I thought about indicating on the EFIS, the reed valves movement with a simple micro switch or even a potentiometer, and have provisioned for that with an extra EMS circuit run to the engine. Or a video camera can be temporarily installed. It will be there for initial testing, but probably taken off after as I feel the airbox doesn’t need to be monitored, other than the slight, but noticeable loss of power . Simply looking into the scoop during preflight will alert to any solid contamination your may have ingested on your previous flight. I fail to see how heavy rain will get to the protected side of the filter. The rain that gets thru the ram portion of the filter will go into the engine. How will a much higher pressure area, essentially vented to the warm air that ‘s cooling the engine, attract rain, sleet or ice? I would chuckle too at the ingested bird scenario, if it hadn’t happened to my brother in his C172, right at takeoff at Hayward CA. About 50 feet in the air and WHOMP! Engine quit and he was able to land in the remaining runway. The front the cowl was completely destroyed by the seagull and the filter was blocked by the feathers and guts. I myself have hit several birds during takeoff in jets over my career. If it hasn’t happened to you, don’t rule out the possibility that it can.
Now, any opinions on which primer is best for airboxes?
Chris Hukill
[quote][b]
| | - The Matronics RV10-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?RV10-List |
|
|
|
| Back to top |
|
 |
flying-nut(at)cfl.rr.com
Guest
|
| Posted: Tue Aug 26, 2014 4:55 am Post subject: FAB wars |
|
|
On 8/26/2014 8:28 AM, Chris Hukill wrote:
snip
| Quote: | Now, any opinions on which primer is best for airboxes?
|
I like CCI primers, though I don't know if they'll fit an airbox!!! 
Linn
[quote] Chris Hukill
No virus found in this message.
Checked by AVG - www.avg.com
08/26/14 [b]
| | - The Matronics RV10-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?RV10-List |
|
|
|
| Back to top |
|
|
Tim Olson
Joined: 25 Jan 2007
Posts: 2879
|
| Posted: Tue Aug 26, 2014 5:57 am Post subject: FAB wars |
|
|
Chris,
You're definitely correct that on takeoff a bird strike to the cowl
is much more likely, so the chances are much higher at that point.
Still, even if you ingested a bird with a standard FAB, and used
the standard door on the bottom, that would still suffice for the
solution. I'm not saying your FAB design is bad, and I don't have
any data on filter sizes for the airflow required and all of that,
and I understand you do. If your design gives plenty of airflow
with no restrictions, and you feel better with it, then I say
go for it, as long as it has no airflow downside. But, I think
that for 99% of the builders, doing anything besides reinforcing
the FAB bottom with Aluminum and having a single-use-then-manual
reset slide door on the bottom really has no big down side.
It'll open airflow for a birdstrike, iced up filter, and provide
plenty of airflow when needed....doing anything more than that
is just going to slow the builder down. I think that too many
people take WAY too long to complete their project, which just
leads to frustration for the builder. There are endless mods
that a person can do, and every 5, 10, 20 hours, especially for
the infernal fiberglass mods, often adds little value for
the effort put in. The fact is, when you are flying your
RV-10, most of these tweaks and mods bring no added joy to
the flying experience, and things such as the FAB mod, I feel
are really no real benefit to safety. Your method is cool,
but it doesn't do anything significant for safety that the standard
FAB offers. (this is NOT an insult or attack on you or your
FAB, as it does look real nice)
It took me 25 months to finish my RV-10 enough to get it in
the air, including the paint. I spent countless wasted hours
in a few mods, especially in the Andair fuel valve. That particular
mod I really do like, but I wasted a LOT of time doing it. Had
I not skipped a couple months of building, and had more builders
in front of me to learn from (I was approx. the 24th flying), I could
have saved probably 3 or 4 months of build time. By the time you
get done with a build, especially doing things like gear leg
fairings, all this work is just tedious and frustrating. So
I personally believe people would be better off taking Van's
advice...."Just build the plane."
Tim
On 8/26/2014 7:28 AM, Chris Hukill wrote:
| Quote: | Glad I could help with the FAB wars. I appreciate the comments and would
to respond to few. The three holes in the back are mathematically the
same area as the intake throat of the injection servo, so if the reeds
are fully open, the airflow would be the same as a hole in the bottom of
the airbox with Vans system. I doubt that Vans did any engineering on
the size of the filter area, as it’s the same filter they use for all
the engine sizes. Off the shelf stuff. The proof is in the pudding. On
my RV8, with a souped up AEIO 360, and the same filter, the loss is 10%,
determined by actual tests. I attributed that loss to the loss of ram
effect, not filter area. The same actual test will be done in my first
25 hours, and I will post results. I thought about indicating on the
EFIS, the reed valves movement with a simple micro switch or even a
potentiometer, and have provisioned for that with an extra EMS circuit
run to the engine. Or a video camera can be temporarily installed. It
will be there for initial testing, but probably taken off after as I
feel the airbox doesn’t need to be monitored, other than the slight, but
noticeable loss of power . Simply looking into the scoop during
preflight will alert to any solid contamination your may have ingested
on your previous flight. I fail to see how heavy rain will get to the
protected side of the filter. The rain that gets thru the ram portion of
the filter will go into the engine. How will a much higher pressure
area, essentially vented to the warm air that ‘s cooling the engine,
attract rain, sleet or ice? I would chuckle too at the ingested bird
scenario, if it hadn’t happened to my brother in his C172, right at
takeoff at Hayward CA. About 50 feet in the air and WHOMP! Engine quit
and he was able to land in the remaining runway. The front the cowl was
completely destroyed by the seagull and the filter was blocked by the
feathers and guts. I myself have hit several birds during takeoff in
jets over my career. If it hasn’t happened to you, don’t rule out the
possibility that it can.
Now, any opinions on which primer is best for airboxes?
Chris Hukill
*
|
| | - The Matronics RV10-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?RV10-List |
|
|
|
| Back to top |
|
|
Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
|
| Posted: Tue Aug 26, 2014 10:32 am Post subject: Re: FAB wars |
|
|
Chris and others,
What I actually had in mind was a plane parked on a ramp in a driving rain storm, with the wind blowing a lot of water into the filter;or maybe someone "helpful" directing a washing hose directly at the filter(!); then taking off into clearing but cold skies. But whatever unlikely scenario, the point is that alternate air is meant to bypass a clogged filter, and I know of no alternate air installation that includes a filter, the logic being that whatever unlikely event clogged the main filter could also clog a second one. Or, a small air leak could result in that second filter slowly getting blocked by dirt. You have to balance that against the also unlikely happenstance of sucking in a stray screw.
As to airflow, remember that the same filter in the -10 has to pass 540/360 = 1.5x more air than in the IO-360. Tests should tell. I would suggest using an 11 month old (dirty) filter in the test, to emulate the real world.
| | - The Matronics RV10-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?RV10-List |
|
_________________
Bob Turner
RV-10 QB |
|
| Back to top |
|
|
Kellym
Joined: 10 Jan 2006
Posts: 1705
Location: Sun Lakes AZ
|
| Posted: Tue Aug 26, 2014 2:35 pm Post subject: FAB wars |
|
|
I would suggest that the airflow difference is not the difference in
displacement, but the difference in horsepower...260/200=1.3.
We know that LOP fuel flow * 15 equals horsepower, and we know that the
ratio in round numbers is 15 air to one fuel. Thus the ratio between air
flow and horsepower is one to one and only loosely related to
displacement. The 300 hp version of the IO-540 will clearly need more
air than the 260 hp version, yet displacement is identical.
As to airflow, remember that the same filter in the -10 has to pass
540/360 = 1.5x more air than in the IO-360. Tests should tell. I would
suggest using an 11 month old (dirty) filter in the test, to emulate the
real world. -------- Bob Turner
| | - The Matronics RV10-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?RV10-List |
|
_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor # 5286
KCHD |
|
| Back to top |
|
|
Bob Turner
Joined: 03 Jan 2009
Posts: 885
Location: Castro Valley, CA
|
| Posted: Tue Aug 26, 2014 3:29 pm Post subject: Re: FAB wars |
|
|
| Kellym wrote: | I would suggest that the airflow difference is not the difference in
displacement, but the difference in horsepower...260/200=1.3.
We know that LOP fuel flow * 15 equals horsepower, and we know that the
ratio in round numbers is 15 air to one fuel. Thus the ratio between air
flow and horsepower is one to one and only loosely related to
displacement. The 300 hp version of the IO-540 will clearly need more
air than the 260 hp version, yet displacement is identical.
|
Kelly, I respectfully disagree. The higher power engines with the same displacement get most of their extra power by having better thermodynamic efficiency (higher compression ratios) so they get the extra power on the same fuel and air flow. You could turn the engine off, but let it windmill, with the throttle wide open. Every two revolutions (4 stroke) it would attempt to pump 540 cubic inches of air out the exhaust, regardless of whether it is a 260 HP version or a 300 HP version.
| | - The Matronics RV10-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?RV10-List |
|
_________________
Bob Turner
RV-10 QB |
|
| Back to top |
|
|
Kelly McMullen
Joined: 16 Apr 2008
Posts: 1188
Location: Sun Lakes AZ
|
| Posted: Tue Aug 26, 2014 6:11 pm Post subject: FAB wars |
|
|
Bob,
Your assumption of more power on equal fuel and air is simply incorrect. While there may be small improvements in efficiency the vast majority of the horsepower change is by getting more air and fuel through the engine. You aren't pumping an incompressible fluid through the engine. Compression and manifold pressure have a lot to do with the power produced and the mass of the air passing through the engine. That is why turbo motors make more power..they push more air and fuel through the engine while the displacement remains the same. Not to mention that primer in military colors produces more power.
Kelly
On Tue, Aug 26, 2014 at 4:29 PM, Bob Turner <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)> wrote:
[quote]--> RV10-List message posted by: "Bob Turner" <bobturner(at)alum.rpi.edu (bobturner(at)alum.rpi.edu)>
Kelly, I respectfully disagree. The higher power engines with the same displacement get most of their extra power by having better thermodynamic efficiency (higher compression ratios) *so they get the extra power on the same fuel and air flow*. You could turn the engine off, but let it windmill, with the throttle wide open. Every two revolutions (4 stroke) it would attempt to pump 540 cubic inches of air out the exhaust, regardless of whether it is a 250 HP version or a 300 HP version.
--------
Bob Turner
RV-10 QB
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=429396#429396
===========
target="_blank">http://www.matronics.com/Navigator?RV10-List
===========
">http://forums.matronics.com
===========
le, List Admin.
="_blank">http://www.matronics.com/contribution
===========
[b]
| | - The Matronics RV10-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?RV10-List |
|
_________________
Kelly McMullen
A&P/IA, EAA Tech Counselor
KCHD |
|
| Back to top |
|
|
cjhukill(at)cox.net
Guest
|
| Posted: Wed Aug 27, 2014 4:00 am Post subject: FAB wars |
|
|
Wayne, I would think that the filter to engine displacement data that K&N provides is meant for applications that have little or no ram effect, like cars and boats. We can easily see that the ram effect is quite prominent in the production of HP in our planes, similar to turbo or supercharging. Testing provides the answers. If the filter is restricting the airflow, it will be evident by the reeds opening to allow more air than is allowed thru the forward portion of the filter. If the reeds stay closed, the airstream is pushing enough air thru the filter, simple as that.
The question of a fire hose assault on the air filter, while parked during a hurricane warrants further study. I’ll take an old dirty filter and put a hose to it (while it’s off the airplane) and blast away, and see how much water gets thru the forward section of the filter, and becomes captured in the aft section, to later freeze. If the amount of water is significant, I will be certain to apply a plug to the scoop whenever parked outside, especially if any hurricanes are forecast. Seriously, that is a valid concern, and deserves further study. An adequate size drain hole will probably be the remedy.
The aluminum plate under the filter is certainly one method of controlling the erosion of the filter thru the thin plastic bottom of the fab. On my RV8 however, I applied a thick bead of silicone to the bottom of the filter, put the filter in place, and bolted the fab together. The film of oil on the filter element works as a mold release and when I remove the filter for cleaning, the silicone remains on the fab bottom. After cleaning, the filter goes right back on the silicone bed, and I have zero wear on the fab bottom with over five hundred hours. Just another way to skin a cat.
Tim, I am in 100% agreement with you on the necessity and even wisdom of a builder spending time and energy on improving Vans already excellent design. A totally stock RV10 is a fantastic airplane. Having built several airplanes however, my mission is a little different than the average builder. For one thing, I have other airplanes to fly, so there is no hurry for me to finish. The reality is that my job as a corporate pilot requires me to spend the vast majority of my time being in town and available to go fly. Building airplanes is a great way to “go to work”, as I like to think of it. The previous planes that I have built always have had items that I thought I could improve on, if I took the time. That’s what I’m doing now. However I certainly would not recommend that approach to other builders who want to get their airplanes flying in any reasonable amount of time.
Chris Hukill
heading off to work
[quote][b]
| | - The Matronics RV10-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?RV10-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
