Canard Community Forum  

Go Back   Canard Community Forum > Safety > Accident Reports
FAQ Members List Calendar Search Today's Posts Mark Forums Read

Reply
 
Thread Tools Display Modes
  #31  
Old 07-10-2007, 11:41 AM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by swinn View Post

What problem are you solving by using a central sump and central point refueling? .
The plan calls for fuel caps on each wing tank with sump blisters. I'm using retracts which frees up the area behind the passenger. Eliminate the blisters and put a large central sump in the hell hole.
Quote:
Originally Posted by swinn View Post
Where can you put a central point filler that will be high enough to fill both tanks?
Behind the passengers headrest. Fill both tanks at the same time. The fuel door locks to prevent tampering with fuel when left on the ramp. It also prevents sending a fuel cap into the prop.

Quote:
Originally Posted by swinn View Post
I can't understand the resistance to a well proven system. 1 valve L-R-Off gives the pilot choices, and maximizes redundancy. Have a problem with fuel delivery? Switch to the other tank. Simple fuel management by the pilot gives choices and uses less components and is less complex.
How about this - Fuel On, Fuel Off. Both tanks empty at the same rate.
Quote:
Originally Posted by swinn View Post
With a 'central sump' have a problem with fuel delivery?
Fuel delivery problem? At what point?
Fuel Valve?
Fuel Pump?
Fuel Filter?
Fuel Cap?

Quote:
Originally Posted by swinn View Post
What are the choices?
The choices what I have the opportunity to make now.
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #32  
Old 07-10-2007, 11:59 AM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by Dust View Post
what about fuel contamination?
??????
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #33  
Old 07-10-2007, 12:00 PM
John Slade's Avatar
John Slade John Slade is offline
Flying TurboRotaryCozyIV
 
Join Date: Apr 2004
Location: KWST
Posts: 3,836
Default Re: how not to modify your Aero canard

Quote:
I'm using every square inch of the hell-hole for a central sump.
The one thing that would put me off doing that is the chance of rupture in an off field landing - especially with fixed gear that could rip out and expose the tank.
Reply With Quote
  #34  
Old 07-10-2007, 12:13 PM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by Dust View Post
??????
Well be sure and only fuel 1 tank at a time Dust.

Quote:
Originally Posted by John Slade View Post
The one thing that would put me off doing that is the chance of rupture in an off field landing - especially with fixed gear that could rip out and expose the tank.
I'm using the infinity R/G. I supose Lynn could address whether or not any damage was sustained by the central sump with this gear configuration.
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #35  
Old 07-10-2007, 12:31 PM
argoldman argoldman is offline
Rich
 
Join Date: Dec 2004
Location: chicago area
Posts: 481
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by John Slade View Post
The one thing that would put me off doing that is the chance of rupture in an off field landing - especially with fixed gear that could rip out and expose the tank.
John,

In the aerocanard, the Sump sits on top of a shelf mounted, in the hell hole, to the top of the recessed area of the gear bulkheads. The rear bulkhead is reduced in hight to orientate the tank with a downward slope toward the rear in flight. The tank is affixed to this shelf by tabs.

In an off field landing, I wonder where the breakage happens with respect to the gear shearing off. the sump tank is a separate entity, not depending on any structure of the aircraft for it's integrity.

Wouldn't one probably worry more about the strakes being ruptured in such a landing??
__________________
CANARDLY CONTAIN MYSELF
Rich
Reply With Quote
  #36  
Old 07-10-2007, 12:33 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by TMann View Post
Well be sure and only fuel 1 tank at a time Dust.
There is a good chance that if there is crud in the tank you are being fueled from, that crud will be delivered to the first tank that is filled, the fuel delivered to the next tank will be clean.

with your setup, there is no chance of that occurring, if there is crud, you are getting it in the tank.

I know you think that there is no possibility of it happening to you, i think the stats show otherwise.

There is another reported phenomenon in our tanks. Crud coming out of them and clogging things up forever. the inside joints are squeezed out and not perfectly smooth, seems crud likes to sit there and come out at the most inopportune times.

I prefer to plan for the worst and accept the best.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #37  
Old 07-10-2007, 12:58 PM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: how not to modify your Aero canard

Easy fix if that is a concern...........split the central sump.
Wouldn't you discover this fuel contamination when you do your fuel sample check in pre-flight?

Better yet ........ don't be the first person to gas up!
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #38  
Old 07-10-2007, 01:05 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: how not to modify your Aero canard

Often times the crud stays in suspension, it does not conviently settle out at the sump or in the case where the crud is in your tank, vibration can cause it to let loose and no amount of testing will reveal its presence.

We should let the tank settle for a while after refueling, but, alas we don't always let it rest long enough and test it before the crud has a chance to settle out.
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #39  
Old 07-10-2007, 02:45 PM
David Clifford's Avatar
David Clifford David Clifford is offline
Member
 
Join Date: Apr 2004
Location: Howell, Michigan 48843
Posts: 587
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by TMann View Post
How about this - Fuel On, Fuel Off. Both tanks empty at the same rate.
Thats what we did on Thane's. Use the "KISS" principal. Several AP's like the idea of an On/Off only valve fed from both tanks along with our EAA Tech Advisor who was out two weeks ago for the final inspection. Its controversial, but its what we went with for simplicity.
__________________
Dave Clifford
Reply With Quote
  #40  
Old 07-10-2007, 03:08 PM
Dust's Avatar
Dust Dust is offline
Super Moderator
 
Join Date: Apr 2004
Location: Troy, Michigan
Posts: 7,963
Default Re: how not to modify your Aero canard

Yes KISS is great, problem it can lull you into thinking it is good.

Our tanks are pressurized by air entering the fuel line vent. with an on/off valve and one tank pressurized slightly more than the other, because that is just how air going through a variety of tubes and fittings works, one tank will empty and the other will not.

Once you start sucking air there will be no way to stop it and get fuel flowing again.

Hopefully this will be observed during flight testing and with just minor replumbing can be corrected before it causes a major problem.

This is just like what happened to thane in his cross country where the 172 on "both" burned from one tank and not the other.

please keep us informed
__________________
Enjoy the build,njut av byggandet, godere il costruire, nyd bygningen, geniesse den Bau, apolafse tin kataskevi, disfrute la construcción, curta a construção, Pidä hauskaa rakentamisen parissa, bouw lekker,uživaj grade?inaslajdaites postroikoi, geniet die bou
dust

maker of wood, fiberglass, foam dust, metal bits and one day a Cozy will pop out and swiftly whisk me from meeting old friends and family to adventures throughout the world
Reply With Quote
  #41  
Old 07-10-2007, 03:13 PM
swinn swinn is offline
Member
 
Join Date: Jan 2005
Location: San Diego, CA
Posts: 76
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by TMann View Post
The plan calls for fuel caps on each wing tank with sump blisters. I'm using retracts which frees up the area behind the passenger. Eliminate the blisters and put a large central sump in the hell hole.
Thats what you plan to do, not a description of the problem you are trying to solve. The question is, what is wrong with a L-R-Off selector and how will the added complexity of check valves, extra tubing and etc... help? What if a check valve gets stuck shut?

More importantly, how will you get a filler tube from the turtledeck of an LongEZ all the way into the tank? You'll have to penetrate the spar in at least 4 places. How will you reach it to fill up the plane? You'll have to climb into the backseat with a fuel pump in your hand, stand backwards and fill the plane up standing in the back seat. You will not be able to reach it with a ladder from behind if thats what you are thinking. I would NOT want my filler tube to be on top of the turtle deck in my LongEZ. It is enough of a pain to check the oil level which I do before every flight.

Quote:
Originally Posted by TMann View Post
Behind the passengers headrest. Fill both tanks at the same time. The fuel door locks to prevent tampering with fuel when left on the ramp. It also prevents sending a fuel cap into the prop.
I could see fuel cap protection as a tiny measure of improvement, however a simple chain fixes the problem with standard caps mounted on the strakes. I still can't see how the fuel can get from behind the headrest to the tanks without making >1" holes in the spar. Is the plumbing going to be exposed to the passenger area? If it is enclosed, what about spillage? You'll need some kind of a drain.

Quote:
Originally Posted by TMann View Post
How about this - Fuel On, Fuel Off. Both tanks empty at the same rate.
Unless you are in a slip, in a turn, the venting delivers uneven pressure, or a check valve sticks. All of these items are unique to common sump systems. There is very little head pressure to overcome even slight differences in venting pressures, tiny debris clogging up a check valve, or any othe problem.

Quote:
Originally Posted by TMann View Post
Fuel delivery problem? At what point?
Fuel Valve?
Fuel Pump?
Fuel Filter?
Fuel Cap?
All of the points you listed are shared between standard systems and common sump systems. I was thinking of a stuck check valve, uneven fuel delivery due to slips, turns, vent problems, etc.... Debris, and water contamination also come to mind, as Dust points out it is often affects one tank and not the other.

You are correct, choices you can make now. Check the NTSB I think you'll find more than one instance of modified fuel systems causing engine stoppage.
__________________
--Scott
LongEZ N1LZ
Photos
Reply With Quote
  #42  
Old 07-10-2007, 04:20 PM
TMann's Avatar
TMann TMann is offline
Got Foam?
 
Join Date: Mar 2007
Location: Omaha, NE
Posts: 756
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by swinn View Post
.... Debris, and water contamination also come to mind, as Dust points out it is often affects one tank and not the other.
And so when do you find out about that contamination problem?
Maybe after you drain the good tank and switch to the bad tank?

Interesting points of view all around. As far as how it relates to the subject of this post, I don't see a central sump as the cause of this accident.
__________________
T Mann - Loooong-EZ/20B Infinity R/G Chpt 10 N200LZ
Got Foam?
Mann's Airplane Factory
We add rocket's to everything!
Reply With Quote
  #43  
Old 07-10-2007, 05:26 PM
David Clifford's Avatar
David Clifford David Clifford is offline
Member
 
Join Date: Apr 2004
Location: Howell, Michigan 48843
Posts: 587
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by Dust View Post
This is just like what happened to thane in his cross country where the 172 on "both" burned from one tank and not the other.
This is the second time you mentioned this incident involving Thane. I did ask him about it after you posted it before and he has no idea what you are talking about. Perhaps you are thinking about someone else. According to him it never happened and I would think HE would know if it ever did.
__________________
Dave Clifford
Reply With Quote
  #44  
Old 07-10-2007, 07:25 PM
--D-- --D-- is offline
Member
 
Join Date: Nov 2005
Location: TX
Posts: 113
Default Re: how not to modify your Aero canard

Quote:
Originally Posted by Dust View Post
This is just like what happened to thane in his cross country where the 172 on "both" burned from one tank and not the other.
This is a common "quirk" in the Cessna fuel system. My lowly C150 (on-off, gravity feed, sump = about 10' of 3/8 fuel line) regularly burns more fuel from one side than the other. Some folks report burning just about all of the fuel out of one side before the other starts feeding. Haven't heard of any engine failures as a result, though.

D
Reply With Quote
  #45  
Old 07-10-2007, 08:16 PM
John Slade's Avatar
John Slade John Slade is offline
Flying TurboRotaryCozyIV
 
Join Date: Apr 2004
Location: KWST
Posts: 3,836
Default Re: how not to modify your Aero canard

I think we've been through this one before... a few times. Here's my take, for what it's worth.

Central sumps and both/off fuel valves both cost you precious, possibly life saving, redundancy.

Gravity feed from two tanks will tend to be uneven. Jim Sower ran out of accessible gas twice with his Velocity for this reason. One of these involved a dead stick landing from Canadian airspace into a US field. The other required rudder all the way home to get the gas to the engine.

A both/off valve will probably cause a dead stick landing if you run one tank dry.

There is no "right answer" to the fuel system question, but for a Lycoming the stock system is as good as it gets.

Fuel management is a critical responsibility of the pilot, but it's nice not to automatically loose the engine if you do make an error.

Cessnas have a much greater head of liquid to get the fuel to the engine. In a low wing, the both option isn't appropriate because this head of fuel isn't there.

DARs don't necessarily think everything through concerning how an off/both system will work on a low wing plane.

Let's hear it from those who've accidentally run a tank dry because they were distracted by other things. I'll start the count. Mine was in a PA28. Flip to other tank (at 800'). Fly home. It's a bit like the old "those who have and those who will" thing.
Now let's hear it for redundancy. I'll start.
Reply With Quote
Reply


Currently Active Users Viewing This Thread: 1 (0 members and 1 guests)
 
Thread Tools
Display Modes

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

vB code is On
Smilies are On
[IMG] code is On
HTML code is On
Forum Jump


All times are GMT -4. The time now is 03:15 AM.


Powered by vBulletin® Version 3.6.7
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd.