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  #41  
Old 10-24-2011, 08:54 AM
Mich48041 Mich48041 is offline
 
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Location: Riley TWP MI
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Quote:
Perhaps another way to secure the tank is with short steel straps designed to bend but not break loose or place tank rivets in tension, in this type of crash. The tank would remain anchored to the channel despite the channel rotating forward. The way I envisage it, the fix could be applied to existing tanks in now flying planes with a few dollars worth of parts and a few hours work.
Great minds think alike. I suggested the same thing in post #12 above. Only my straps are longer and above the attachment points. There have been lots of good ideas presented here. I believe that Van's will come up with a well engineered solution. Not only do they have to design a fix, but the tank has to be tested, a lengthy process.
Joe Gores
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  #42  
Old 10-24-2011, 09:02 AM
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RDOG RDOG is offline
 
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Quote:
Originally Posted by DonFromTX View Post
I am surprised nobody has suggested some unlatched canopy training, I think that is what I will include in my transition training! I recall the alarm I had the FIRST time I took off with the door open on my Cherokee 140. Times after that were of no concern at all except to decide shall I return and close it, or just go on to my destination with it hanging open.
If I am counting correctly, this is the THIRD incident of this type on an RV 12 that we are aware of.
Don,
The closest we get to that training is we have opened the canopy on roll out when both Jetguy and myself were in the aircraft. We've noticed the canopy does pitch the nose down when opened. We will not be practicing that. instead we like flow training before taking the runway. fuel, flaps, canopy, trim, choke and then and only then throttle up for takeoff.
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  #43  
Old 10-24-2011, 09:34 AM
dick seiders dick seiders is offline
 
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Checklist including canopy a good proposal. The off field landing is the concern which likely would (could) cause the gear rotation. The fixes suggested all have merit, but if I were making a mod I would not attach to the channel -period. Anything that can support the front of tank NOT connected to the channel is a step in the right direction. I do however suspect the best advice is to wait for Vans to solve the problem for us.
Dick Seiders
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  #44  
Old 10-24-2011, 10:11 AM
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Bill_H Bill_H is offline
 
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I hesitate to ask - and just an unthought-through additional idea - but what if those forward two supports were wooden or plastic dowels?. Something that could hold the weight to 4+G and still be weak (or flexible) in shear. Thick of a plastic tomato plant stake about 3/8 inch in diameter - some of those even have a reinforcing wire in the center. Nothing wrong with a little brainstorming at this point.
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  #45  
Old 10-24-2011, 11:13 AM
Mich48041 Mich48041 is offline
 
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Quote:
Would it be prudent to have a warning light/switch on the canopy to make sure it is closed before takeoff? Almost as important as the wing attach warning switch with flashing panel light?
Good idea, maybe something like this:

The trouble with a simple circuit with a warning light and a switch is that the pilot will get used to seeing that light being on and will ignore it on takeoff. What is needed is a warning that will ONLY occur on the takeoff roll. I envision a microprocessor that that will receive input from the canopy switch and from the tachometer. When the canopy is open and the RPM is above a set-point, the microprocessor output will turn on an audio and visual alarm. A voice that yells CANOPY in your headset would be ideal. Off the shelf components are inexpensive. The hard part is designing the circuit and writing the microprocessor program.
Of course a checklist will work too. But pilots get complacent or distracted. Or they use a checklist, but then open the canopy due to a delay. It has happened and will happen again.
Joe Gores
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  #46  
Old 10-24-2011, 11:33 AM
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Jetguy Jetguy is offline
 
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Question A blot that would shear sounds good.

I think Bill may be on to some thing. How about a plastic bolt or an aluminum bolt? If it would shear on impact that maybe the easiest fix.
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  #47  
Old 10-24-2011, 12:41 PM
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MartySantic MartySantic is offline
 
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Have not had time to research the subject, but, breakaway bolts are available. Large ones are used on fire hydrants. Believe they have a hollow core.

Such would take a bit of testing to ensure they do not shear under g-load.
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  #48  
Old 10-24-2011, 12:47 PM
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Geico266 Geico266 is offline
 
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Quote:
Originally Posted by Bill_H View Post
I hesitate to ask - and just an unthought-through additional idea - but what if those forward two supports were wooden or plastic dowels?. Something that could hold the weight to 4+G and still be weak (or flexible) in shear. Thick of a plastic tomato plant stake about 3/8 inch in diameter - some of those even have a reinforcing wire in the center. Nothing wrong with a little brainstorming at this point.
Quote:
Originally Posted by Jetguy View Post
I think Bill may be on to some thing. How about a plastic bolt or an aluminum bolt? If it would shear on impact that maybe the easiest fix.
The subject has come up and it is a good one, but the headless bolt fix does offer shear strength ( side load) to support the forward end of the tank. The rear bolt holds the tank in place, and the front two headless bolts support it. Certainly, there are many ways to skin this cat, but like another poster said the goal is to not use the center section as a support at all.

I am going to use the headless bolts & strap wait and see what Vans comes up with.

JMHO.
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Last edited by Geico266 : 10-24-2011 at 12:50 PM.
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  #49  
Old 10-24-2011, 01:28 PM
E. D. Eliot E. D. Eliot is offline
 
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Location: San Pedro
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Default New tank design

IMHO, and not being any kind of an engineer, I think that it's time for Van's to rethink the design of the fuel tank. Some of you who are a lot more knowledgeable than I seem to be saying that we can expect the current design tank to be compromised in the event of an off-airport emergency landing. I don't know if the pilot of this particular accident was 'lucky' or not but if I can expect a gasoline shower in my 12 if I have to land in a field and flip it or hit hard, then I don't want to fly a 12. Simple as that.

Maybe a 'seamless' rank as described by some of the previous posters is in order. I don't mind paying a lot more $$$ for a safer design fuel tank.
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  #50  
Old 10-24-2011, 01:29 PM
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engineerofsorts engineerofsorts is offline
 
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I'm just a bit confused about the concern with shear of these bolts. Aren't we really trying to still avoid them shearing, but have them bust when over-tensioned? Hence the headless bolts retain shear strength, keeping the tank from coming loose when inverted or hard landing, while having no tensile strength (with the bolt head cut off) such that the rotating U-channel can't pull the tank apart. ????? A strap is then mayhaps needed to keep the tank in place in the case of the U-channel rotating and the plane inverting???
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