FredStork

Bandit, glad you had a happy end on your "adventure". My mantra when flying is "Always know where to land". Sometimes it prevent me from going where I want. "Height is safety" is another one... 
C5Engineer, you worry me... I can easily see 3 (bad) scenarios, there might be a 4th good one but 3 against 1 is not the odds you want.
A)  If your caps are relatively airtight the fuel flow will work only a short time (just enough not to return safely to the airfield...). As fuel lines are narrow very little, or no, air will go backwards through the line and replace the used fuel. A vacuum created when using the fuel would easily stop the flow. Even with some air coming through the caps it would reduce the flow as the flow of fuel will have to compete with the less effort flow of air from the inboard tank vent. See also (C).
Your vented inboard tank will be all you have to fly on.
If your caps are not even slightly airtight 2 things could happen...
B) A vacuum is created by the airflow and you can ask C5Engineer how fun that is...
C) A vacuum is not, or only partially, created by the airflow and the outboard tank remain, more or less, vented. If the ventilation of the inboard tank is good (vent turned into the wind and therefore creating a slight pressure in the inboard tank) this pressure can prevent the flow from the outboard tank. The result will be similar to (A), but maybe a few miles later...

D) Sure, you could always be lucky and have just the right amount of air getting through the caps and not to high pressure by the inboard tank vent... That is, however, walking on very thin ice...
And the really stupid scenario is when we have a vacuum on the inboard tank vent and it siphons fuel into the air directly from the correctly vented outboard tank... I think you would feel the smell easily so this probably would not go too far... 
So...
The outboard tank is feeding the inboard tank and any pressure in the inboard tank would be of harm as it could counter the flow into the inboard tank... 
We want a positive pressure in the outboard tank that will help the fuel flow but we actually don't need the additional pressure in the outboard tank.
Any vacuum created by the outboard caps (or bad vent line) will reduce the fuel flow and could even drain the outboard tank if the air but only if the fuel drained is replaced by other fuel or air. The fuel, or air, in the outboard tank could only be drained if replaced through the fuel line. The fuel line goes to the inboard tank or eventually to another outboard tank.
We are getting close now but let me tell you a story first.
I have, like the most of us, a Mikuni fuel pump. It is small and doesn't look very impressive.... I have a rather big (6 liter) inboard tank made of some fancy, very sturdy, plastic. The inboard tank has metal fitting molded into it. This inboard tank was full and both the inboard vent and the feed from the outboard tank were turned off... This was obviously not intentional...  
I taxied to the end of the field when the engine started coughing slightly. I increased the throttle and it stopped coughing, back on idle it coughed again so I taxied back. Better safe than sorry. That little piece of Japanese fuel pump had just done its job, sucking the fuel out of a closed container. The inboard tank was now deformed, imposed, to a degree I could never have done even by jumping on it. The metal fittings were no longer airtight so I had to get a new inboard tank.
This to say that we don't only count on gravity flow, we are getting the fuel sucked through the lines with more (negative) pressure than we might expect...
Yes to fuel, no to air...
The easy solution is to have an inboard tank without permanent ventilation. The only time you need to vent the inboard tank is when filling it up, i.e. when the outboard tank is empty and the inboard tank is being used as the last fuel supply and you fill up the outboard tank. With fuel in the outboard tank you can now vent the inboard tank until it is full (i.e. filled from the outboard tank). The inboard tank vent can therefore come out under the belly rather on top where you don't want it.
The outboard tank should always be vented. Creating a positive pressure (venting into the wind) is better as it will in best case create a positive pressure and in worst case at least not a vacuum. However, as explained above, a neutral vent will work just fine and even a vacuum will largely be compensated by the fuel pump suction (in the speeds we fly) under the condition that there is not another open vent in the system (like an always open vent on the inboard tank...).
Having a vented inboard tank is normally not a problem as long as the the outboard tank is correctly vented into the wind with a positive pressure created. But if the pressure is too great the inboard vent can bleed (we have seen many damaged lean roofs due to that). 
However, the only added value of having the inboard tank always open is when you cannot see, or measure, the fuel level in the inboard tank. The original Avid Flyer inboard tanks were all metal and no probe and therefore had to be always vented. 
Once air is in the inboard tank it will only be replacing the fuel going out with the same amount going in. I.e. is you empty the inboard tank to say 50% after having emptied the outboard tank, it will remain on ~50% even when you top of the outboard tank. (Sure there will be a slight compression of the air in the tank and maybe you will have it 55% filled...). Just temporarily open the inboard tank valve until new fuel chases the air... 
As controlling the fuel and air flows is critical I would suggest avoiding having outboard tanks communicate as an empty tank is a tank filled with air - feeding into what is supposed to be a fuel line! By manually switching from one wing tank to the other we keep a better control of the flows and the fuel remaining.
Placing a probe alerting when the fuel level goes down in the inboard tank and a led on the dashboard has made me fly more relaxed. Once the led start flashing I switch to the other wing tank, purge the air in the inboard tank through the inboard vent valve until the led stops flashing.   
 
Sorry about a long, soap box, post...
Regards
Fred
 
 
 
 
 


 
 
    
 

I have to admit it, yours is bigger than mine... 
 
 

Jim,
I would recomend an ND8 filter (neutral density, the number correspond to the number of f-stops) going lower and you are likey to still get artifacts. If your camera is good (while still cheap) don't get too cheap on the filter or you will end up with negative impact on the picture. And bad filter on a not so good camera... Hoya have good filters for decent price.
Thers is a company selling ridiculously expensive kits around gopro for pilots and they are providing ND8 filters so I assume 8 is close to optimum.... 
Another hint is to always use the filter, even if the prop is not in view on all takes as "neutral" isnt always that neutral any you will get different colortones with and without the filter.
Through Amazon you can get filter adapters for most gopro like cameras as well as filters. For an "always on" setup it could be worth getting an additional housing and glue the filter in place replacing the original protectiv glass. If you use a super wide mode it is easy to get the corners obstructed if the filter is not close or wide enough.  
I'm working on this summers film and have been using ND8 filter on my gopro. The result is very good, you can still see a slight blurr from the prop but none of the classic strange artifacts. I'll post the link as soon as it is ready.
regards
Fred

and who is not afraid of taildraggers...

I can only agree... you have been given some questionable advice. Sounds like they would have an financial interest in what they propose or have some aversion to cool experimental airplanes. As suggested above, get a second opinion from a different CFI or flight school. Maybe someone on this list can suggest a more open minded CFI in your area.
It is always so easy to explain why things are difficult or impossible...

There are only 2 kind of Avid Flyer pilots, those who have already hurt their head against the flaperons and those who will hurt their head against the flaperon.
(got a nice mark on my forehead this summer...)

The French Avid Flyer Owner association try to meet yearly for a fly in to share the latest war stories and admire each others planes...
This year we met at Sagy, a small private Airfield, in Bourgogne (Burgundy). The meeting was arrange by Philippe who a few years ago fell in love with the Avid Flyer and is ever since telling us he will get one soon... While waiting for the right opportunity he is successfully reviving the French Avid Flyer Association. I like that spirit! I met him a few days ago and he told me he is very close to buying one... To be followed... 
Anyway... as usual I brought my camera and made a film to capture the ambiance and to get us all a souvenir. I'm not sure it has a great interest outside the group... Notice how the Champagne get delivered by auto-giro... 
The French Avid Flyer Owner Association meeting 2016
Note that due to copyrighted music the film might not be available on handheld devices like phones and tablets and not at all in Germany...  

I recall a recommendation (from where?) not to open and fly with the doors open above 100 km/h (60 mph). Not really a big constraint. I don't think there is a limitation if you remove the doors. 
The doors will stick to the wing as long as you fly "clean" (the same with windows in the doors like I have but as I open the window to take photos and fly with my knees I have installed gas springs on the windows to keep them open under all conditions). See also http://avidsimonini.blogspot.fr/2015/06/my-best-modification.html 
Make sure you turtle deck is well secured before you slip on the open door side... A slip with both doors open is probably a great way to clean your plane and get rid of maps, logbooks and other stuff... I normally takeoff and land with the doors and window closed, the door, when open, is not really adding any aerodynamic benefit to the wing.
 

The inland, Blois and back home again
I had bad internet connections the last days so here is the wrap up of the end of the trip...
As mentioned I headed for the center of France. I wanted to go and visit the current owner of my previous plane, a J3 Kitten. It turned out the owner was gone on holiday but I have seen my old plane in the hangar. At the airfield I met an English couple who were there waiting for some friends arriving from the UK in an ultralight as a local English ultralight school (yes, local as "in France and not very far away") were organizing their yearly "Chilli and Cheese Fly In". I rapidly found myself invited, flew to their private field and spent an excellent evening.
Next morning, Saturday, I went to Blois and the yearly Ultralight fair, biggest in Europe. This is an event where you will meet just everyone and see all the new stuff and trends. Rotor wing is still the strong trend with a refinement of the top of the line auto gyros and new sexy helicopters. There were also more high performance fixed wing planes, one difficult to tell a part from the other, flying at 300 km/h and with price tags like luxury cars than you could shake a stick at. Maybe the really new thing this years was an timid, but noticeable, increase in tail wheel planes. I particularly liked the Stampe replica (full scale and still class ultralight in France!).
Blois was the last stop of my trip and from there I had a 3h15 flight home. It has been 2 fantastic weeks and I will live long on this. I will be doing a film about the trip but seen the volume of the material I have it will be sometime during the autumn...
Thank you for your comments and  encouragements!
 

Dusty,
the truck is the "different but rather nice restaurant", I guess it started with just the truck and a few plastic chairs and then cames some organic growth... Ther is even a small stage inside noe for rock concerts once a week...

The last island
As expected, Monday morning the wind had dropped and I could leave Ile d'Yeu and continue my journey. Next stop was Ile d'Oleron, the last of the 3 islands. Having lost 2 days I planned only a lunch and on the VAC it said "restaurant at the airfield". When arriving, in a rather different but very nice restaurant, it was to be informed by the owner, having his lunch with his parents, that the restaurant is closed on Mondays (and Tuesdays as we were past the magic French date "August15th"....) BUT if I didn't mind sharing their bread, sausage, pate, ham and melon I was more than welcome... A very nice meal and the father's stories from his career as helicopter pilot continued while he drove me to the filling station in his cabriolet...
After that, 2 days with wife and children in the Basque country before taking off for the center of France.  So much for sightseeing... I noted a greater than normal EGT difference between the 2 cylinders and took out the spark plugs. One spark plug had some "stuff" between the electrode and whatever the other part is called... I cleaned them and the temperature was back to normal. My theory is that they don't like to start drowned in oil... While the new, longer, sparkplugs allows me to start even after a longer period of rest one sparkplug of each cylinder is still drowned in oil whilst the other is protruding and allows the engine to start. So, short stop not a problem, longer stop better purge the oil before starting. It is very hot here, 37 degrees celsius, 100 Fahrenheit, and the engine is taking excessive RPM at takeoff if I pull full throttle. When I grow up I will get an in flight adjustable prop... To be followed...  

Grounded in paradise
In my dreams I'm an amazingly skilled daredevil pilot, flying in any condition and never afraid of anything. Well, today is reality and I find the gusty crosswind too strong both here for takoff and where I'm supposed to go next to be comfortable.
And it is expected to be the same tomorrow... Unless there come a dramatic change in the weather I will stay another 2 nights here.
You don't have to feel sorry for me, where are worse places to be grounded than Ile d'Yeu....
And it gives me ample time to prepare both myself and the plane for the next leg.  

I confirm, no need to feel sorry for me... (Note the mussel side reading - available at Amazon...)

I built and installed a Lift Reserve Indicator.
Does it look cool? Yes.
Does it prevent me from landing like a kangourou? No.
I should probably spend more time calibrating it, learn how to get the most out of it and actually look at it... 

Well, my mother knows nothing about airplanes and what is good for a real pilot. (but there are ladies with hair on their chest who do know  http://www.ladieslovetaildraggers.com/)
While it is something I try to forget, I did all my flight training in that other, unmentionable, kind of planes and I'll rather be chained to a cliff and have my liver eaten by crows than do that (or eat broccoli) again...
Did I mention I never shave before flying?  

If we can't laugh about pink shirt pilot wannabes with planes looking at their feet rather than the sky, what should we laugh about? Our selves?   
I think those jokes are very funny, but maybe that is because I am a real oil stained, wind in my face, lonesome cowboy tail dragger pilot with a proud 0 (zero!) hours on pink shirt nose-draggers since I got my licence.
 

Thomas,
I have not lived in Sweden for many years now and don't know how easy it is to find bolts in inch... I guess you already know that Aircraft Spruce have EU branch shipping rapidly from Germany.
Here is a direct link to the wing strut AN4-16A bolts you are looking for (note that all bolts have the same photo so it will not look right) 
http://www.aircraftspruce.eu/bolt-undrilled-an4-16a.htm 
And here is the link to the AN5-30 bolt to replace the removable pin attatching the wing when folding 
http://www.aircraftspruce.eu/bolt-drilled-an5-30.htm 
 
Regards
Fred

Thanks for the link to the guide! I lean't something today... And your eye charts are readable when clicked - and together with the guide very useful!

Thomas,
is the jury strut bolts or the wing strut bolts you are looking for?
While you always need the right quality bolts, the jury strut (that prevent the wing strut from bending during negative G) as less critical than the wing strut bolts.
In my builder manual the jury strut bolts have reference AN3-4A (16 in total on the inventory list, 8 used for the jury struts)
The wing strut bots have reference AN4-16A (4 in total on the inventory list, all used for the wing struts)
But I don't have the dimensions and they dimensions are not on dholly's eye test charts... only part numbers and descriptions...
Not much of an help I'm afraid...

Hej Thomas,
this is the theory (or at least one of them...), making yours a Model C according to serial number (mine is #479 and considered a C Model with Heavy Hauler wing):
Model A

N99AF, the trigear prototype, won the Best New Design Award at Oshkosh in 1983.

The Model A's fuselage had wood stringers along the fuselage sides and bottom. The fuel tank was behind the instrument panel. It used cable-operated brakes with narrow "wheelbarrow" wheels. The engine mount was welded to the fuselage.

Model B (serial numbers below about 250)

The Model B had a separate engine mount bolted to the fuselage. A radiator was mounted outside on the passenger's side. Aluminum wheels were used. There was one diagonal piece of tubing across the cockpit ceiling.

The Heavy Hauler wing was first offered on late Model Bs. Although the spar tubes were thicker aluminum (.083 inches rather than .063) and the lift struts were heavier (7/8 inch rather than 3/4) the rib spacing was still 18 inches.

Model C (serial numbers about 250 to about 900)

The Model C's fuel tanks moved to the wings. Matco wheels and hydraulic brakes were used, and a castoring Matco tailwheel with 1-1/4 inch tailspring. The radiator was mounted inside the cowling on the passenger's side. Tubing replaced the wood stringers along the fuselage sides, but a wood stringer was still used on the bottom.

The single diagonal piece of tubing across the cockpit ceiling was changed to a stronger triangular structure.

The Heavy Hauler wing rib spacing was changed to 12 inches. The Aerobat wing had the same features as the Heavy Hauler but was 6 feet shorter (24 feet vs 30 ft). The Commuter wing was a short STOL wing.

Model D / Mark IV (serial numbers about 900 to about 1550 with D suffix)

The cowling was redesigned to accommodate two radiators at the front. The cowling was split horizontally, rather than vertically as on earlier models. In order to accommodate different engine choices, the vertical stabilizer was straightened and different engine mounts were built for left or right turning engines or gearboxes.

The tailwheel spring was increased to 1-1/2 inches. All fuselage stringers were now tubing. A luggage compartment was added behind the seats with a door to the outside.

From 1995 only the heavier .083 inch spars were supplied.

Bandit (serial numbers about 900 to about 1582 with E suffix)

Magnum (serial numbers with M suffix)


Regards,
Fred (or Fredrik among Swedish people...)

Excellent, thanks Nick. The link works fine!

It is always great to see that Avid Flyer pilots travel with their planes. I'm impressed by your coast to coast trip and, without any other comparison than the route, the illustration reminded my about the "Powder Puff Derby of 1929: The True Story of the First Women's Cross–Country Air Race" , a book I just received. 
Tell us more about your coast to coast flight... How long did it take, how many stops, ....?
Regards
Fred
 

...and to answer my own question...
I just bought a "aLLreLi 42W 5-Port Intelligent Car Charger Kit" (with a name like that you can't go wrong...)
While not mentioned at the US Amazon site, at the French version of Amazon they talk about the "superior quality components" and that it will not generate static or other disturbance to radio, Bluetooth, WiFi or 3G... Interesting difference... humm...  But I found no customer reviews mentioning radio interference (and this is a frequent comment) so for 14$ gave it a try...  
https://www.amazon.com/aLLreLi-Intelligent-Charger-Double-Sided-Devices/dp/B0122P1WFW/ref=cm_cr_arp_d_product_top?ie=UTF8 
It is very convenient with the long cord that can be cut and used for easy wiring. While the cigar lighter plug is converting to 5 volt the big box get 12 volt through the cord and has it's own converter.
In flight, I connected both my iPad and iPhone to the charger, verified that they were charging, and tried the radio. First I though the radio was dead, but no, there was just a perfect absence of static and other electric interference...

A second person is the preferred option but Steve's method works well using a glue clamp. A piece of string is good help for the last wrap...