WWI Replica Safety

[Joe Perkel]

A bit late to the discussion as I've been distracted otherwise.
We have established via empirical evidence, the following.....

-WWI fuel system design, is not up to serviceable standards.

-Adherence to the standards and recommendations of the various Advisory Circulars and other published material, is simply the best course of action for any aircraft.

A caveat.....

It is not an accurate museum quality authentic replica without an authentic fuel system.

....and therein lies the dilemma!

[Machinbird]

Joe,
Accurate museum quality replicas probably belong in museums where they won't hurt anyone. The rest of us who are building an aircraft to fly have to make many "adjustments" to the original designs in order to fly safely and reliably.
About the best you can hope for with one of these latter machines is that it looks like the original, sounds like the original, flies at least as well as the original, and that it is safer than the original.
No real dilemma, just a whole slew of engineering decisions. Once you decide your build belongs in the air, that sets the path.
Sid

[Joe Perkel]

Originally Posted by Machinbird

Once you decide your build belongs in the air, that sets the path.
Sid

Very well said Sid!

Perhaps dilemma is the wrong choice of word. "Decision", is the more appropriate choice.

[j ferguson]

Joe,
I didn't intend to condemn the FE2b fuel system which John McKenzie has so kindly described. I think it is a very intelligent scheme. Its principal advantage is the gravity feed "service" tank with the simple sight gage. This tank acts as a buffer between the pressurized tanks and the carburetor. This reduces the possibility of the pressurized fuel system causing any mischief with the carburetor float system. John M. reports that you could valve pressurized fuel past the service tank directly to the carb. if you wanted.

In the event that the wind-driven air pump fails, you can hand-pump fuel to the service tank from either of the other tanks. A short burst of pumping might be sufficient to fill the service tank so you could fly a while before repeatng the procedure.

On a plane lacking the gravity feed service tank, you would have to hand pump repeatedly to keep fuel moving in the event of an air-pump failure.

Were check-valves installed on other air-pressurized systems to preserve pressure in event of air-pump failure?

Finally, It might be good to know where the overflow on the FE2b service tank goes. I would think it couldn't go to either of other tanks because they are pressurized.

Once you accept the idea of having pressurized fuel tanks, the FE2b system seems a good one.

[John McKenzie]

Hi all , John , yes , I thought I must have missed something when Joe posted about WWI systems not being up to serviceable standards..in view of previous postings ,..All in all ,it didn't seem so bad to me , but as John says , "once you get over the idea of preasurised system "...Don't forget , it had to carry a LOT of petrol to get the range ,which would not be necessary for todays useage, so perhaps you could dispence with one of the preasure tanks ...BTW , the overflow pipe comes out of the service tank at the front , goes slightly forward and then up* , over the L/E and back over the top center plane and discharges at the trailing edge ,(on the opposite side of C/L to the exhaust )....Ithink SE5a was similar in that fuel could be delivered to the motor either under preasure from the main tank , ahead of pilot , or from the header tank in the leading part of top C/S ,ahead of front spar ,(fed from main tank )...The main tank has a quantity gauge (Simms) , however the service tank has not ,.and this similarly discharges at T/E top wing , outboard of cockpit ...Many* preasureised systems that come to mind (in WWI ) on either side , seem to use the system in conjunction with a header or service /gravity feed.There are of course , many exceptions to this .Some use a mechanical air pump , while others have engine driven pumps .all (?) have a cockpit hand pump also, It is possible ! that both would fail at same time , but then , the idea of keeping the service tank topped up has the advantage here , at least to get you down safely ...Regards* ..John.

[Joe Perkel]

The discussions are very helpful in that it makes the individual builder think about the issues at hand, that alone,...is worthwhile.

Food for thought....

...Imagine a transatlantic crossing in a Viking Longboat or centuries later, a Spanish Caravelle.

...The thrill of breaking the 80 mph barrier in a Steam Locomotive.

....a mission at 10,000' over the Verdun in a wood and fabric airplane.

....in my own lifetime, today's shuttle compared to Glenns spam can.

All of which were the pinacle of technology in it's own time.
We do have the advantage of hindsight don't we? Nice to be able to benefit from it.

[Machinbird]

A couple years ago we had some discussion about structural deformation (buckling) of the cockpit longerons being the proximate cause of Gontermann's death in his Dr.I crash. Survivability lesson from the past
At the time I had proposed stiffening the cockpit bay of a steel tube replica by inserting carbon fiber rods into the longerons to help stiffen them.
I recently had an opportunity to discuss the idea with an engineer who had current experience with carbon fiber pultrusions. He recommended against use of carbon fiber to reinforce steel tube by pointing out that the carbon fiber is conductive and would likely promote corrosion in the longerons. As others suggested, he suggested that it would be better to both increase diameter and wall thickness of such critical tubes.
So if you had been considering my crazy idea to beef up your replica's cockpit using carbon fiber, probably best not to.

[Joe Perkel]

Originally Posted by Machinbird

A couple years ago we had some discussion about structural deformation (buckling) of the cockpit longerons......"

So if you had been considering my crazy idea to beef up your replica's cockpit using carbon fiber, probably best not to.

Sid,

Very magnanimous of you to share a discovery of fact which disproves an earlier theory. Some builders occasionally will keep such mistakes under their hats, particularly ones which cost them significant capital investment. This kind of sharing, (before or after an event), can only help the community of replica builders. Keeping mum helps no one.

Thanks Sid!

[Brad]

Originally Posted by Machinbird

A couple years ago we had some discussion about structural deformation (buckling) of the cockpit longerons being the proximate cause of Gontermann's death in his Dr.I crash. Survivability lesson from the past
At the time I had proposed stiffening the cockpit bay of a steel tube replica by inserting carbon fiber rods into the longerons to help stiffen them.
I recently had an opportunity to discuss the idea with an engineer who had current experience with carbon fiber pultrusions. He recommended against use of carbon fiber to reinforce steel tube by pointing out that the carbon fiber is conductive and would likely promote corrosion in the longerons. As others suggested, he suggested that it would be better to both increase diameter and wall thickness of such critical tubes.
So if you had been considering my crazy idea to beef up your replica's cockpit using carbon fiber, probably best not to.

Another thought on the same line... with less weight penalty, although only a minimal increase in strength.

How about using a sprayed-in foam to help prevent tube deformation? It would help to maintain the round shape of the tube and prevent buckling.

Or... maybe just a plain (ok, "finished" with polyurethane or epoxy) wooden dowel? Wood is essentially non-conductive to begin with, and completely coating it would help prevent swelling/shrinking with changes in humidity.

It would help prevent the tube from collapsing, which is what happens when a tube buckles.

[j ferguson]

Brad,
Do you think there is a foamable material available that has enough compressive strength to help a tube resist buckling? If so, this is a neat idea.

I'm reminded of older English Morgan Automobile frames which were steel tubes or channels around Ash timber.