Author Topic: NACA 66 Special A/BGS  (Read 596451 times)

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Offline Jon

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Re: NACA 66 Special A/BGS
« Reply #900 on: October 02, 2013, 10:42:12 PM »
I'd be interested in some pictures too please Rob, I don't do Facebook.

If both the assembled retainers and the tooling if that's ok.

Thanks
jon
Underhouse Engineering
Luck = Opportunity + Preparation^3

Offline tauruck

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Re: NACA 66 Special A/BGS
« Reply #901 on: October 02, 2013, 11:27:39 PM »
Jon, You don't do Facebook?????? :-o :evil:

Offline SPARKY

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Re: NACA 66 Special A/BGS
« Reply #902 on: October 03, 2013, 12:49:37 AM »
SMART man  :cheers:
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

Offline Stainless1

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Re: NACA 66 Special A/BGS
« Reply #903 on: October 03, 2013, 11:22:00 AM »
Jon, You don't do Facebook?????? :-o :evil:

What's this facebook thing I keep hearing about... the way someone collects info on you to sell to the highest bidder?

Back to subject...
Wow, what a project, you guys should be extremely proud of what you have accomplished over the last year.  See you on the salt.   8-)
Stainless
Red Hat 228.039, 2001, 65ci, Bockscar Lakester #1000 with a little N2O

Offline tauruck

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Re: NACA 66 Special A/BGS
« Reply #904 on: October 03, 2013, 12:34:29 PM »
I don't do it either.

Offline robfrey

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Re:
« Reply #905 on: October 03, 2013, 05:33:03 PM »
The crazy part about this body mounting system which unlike a dzus fasteners that add very little structural strength,  this closely spaced screw and washer system really adds to the overall strength of the chassis. We have seen the tell tale signs of this like minimized flex when lifting car from its center balance point. How Eric aligned the fibers of the composite also has something to do with  how stiff the overall structure is. Can't put it into words but you can almost feel the car get stiffer with each fastener that gets installed.


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Offline robfrey

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Re:
« Reply #906 on: October 03, 2013, 07:11:35 PM »
Best way we found for
Mounting a panel:
1) position panel against body mount
2) drill .159 hole thru panel and body mount.
3) Clearance hole in composite panel. This is important as you do not want to tap composite or it will wear your tap fast.
4) Tap 10-32 thru body mount
 attach panel with 10-32 button heads. Use alloys as stainless may gall and hex will wear rapidly.
5) When you are happy with how panel fits (also adjacent panels) remove button head screw (1 at a time) and c-sink / c-bore panel with custom tool. You will notice that not all thru holes will not align perfectly with tapped hole once you get all the temp fasteners in and it's been on and off a couple of times and temperature  of shop has changed etc. other factors that will influence how far off some holes will be how large the panel is, how much it needed flexed to bring panel to the body mounts, the phase of the moon, your biorhythms, etc. Now here's the cool part, as long as you can get the pilot of custom tool (.156 dia) into the tapped hole, the custom tool will cut the c-sink  and c-bore concentric with the tapped hole. It will sort of recenter the hole in the composite panel and that is a beautiful thing.
6) When all holes are completed, you can remove the panel and install nut plates in body mount. We have devised a couple of tools to speed this process also. Let me know if you need them and I will email you the PDF to make the tools.
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Offline SPARKY

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Re: NACA 66 Special A/BGS
« Reply #907 on: October 03, 2013, 07:25:09 PM »
WOW   is the little piano hinge the chute door?  I was amazed that it flew open and just stayed there--no fluttering or flopping!
Miss LIBERTY,  changing T.K.I.  to noise, dust, rust, BLUE HATS & hopefully not scrap!!

"Security is mostly a superstition. It does not exist in nature, nor do the children of men as a whole experience it. Avoiding danger is no safer in the long run than outright exposure. Life is either a daring adventure or nothing."   Helen Keller

We are going to explore the racing N words NITROUS & NITRO!

Offline robfrey

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Re:
« Reply #908 on: October 03, 2013, 07:50:49 PM »
No , that pic is of the canopy hinge which is exactly the same as the parachute door.
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Offline robfrey

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Re:
« Reply #909 on: October 03, 2013, 08:18:41 PM »
No , that pic is of the canopy hinge which is exactly the same as the parachute door.
The piano hinges all stick up off the body surface about .06. Making them flush will be a task that we should have done by Speedweek.
We will just need to fab some .06 spacers to fit between the hinge and body.
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Offline Jon

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Re: NACA 66 Special A/BGS
« Reply #910 on: October 03, 2013, 08:42:56 PM »
Thanks Rob
Couple more questions if you don't mind please:
How thick is your body shell? I have Bidirectional cloth (can't remember what weight) and no glass experience.
I'm not sure how many layers to put on, figure if I get a decent resin to cloth ratio and end up about the same thickness I should be close.

How does the piano hinge go working on a compound curve?

Thanks
jon
Underhouse Engineering
Luck = Opportunity + Preparation^3

Offline bbarn

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Re: Re: Re: NACA 66 Special A/BGS
« Reply #911 on: October 03, 2013, 08:46:21 PM »
WOW   is the little piano hinge the chute door?  I was amazed that it flew open and just stayed there--no fluttering or flopping!

That was one of the tests we wanted to perform last weekend. The doors were mounted at a specific angle to actually "fly" in the open position.

The goal was to get the angle perfect so the door didn't slam open or stick shut. Getting the angle right meant the door would open when released even if the spring on the pilot chute didn't push the door open.

We also couldn't put a tether on the primary door since it would get in the way of the secondary if we needed it. The angle seems pretty good as you stated in your comment, it rides pretty stable in the open position.

We didn't get a video of the secondary chute door in action, it wouldn't have mattered anyway. When we deployed the first chute, it damaged the secondary chute door. It took many views of the video to determine how, but it  was actually a pretty simple problem.

If you watch the video of the chute release, right when the tether goes taunt, you can see the door get booger'd up. If you pause it just right, you can see a green sheath being thrown up. It turns out the green sheath is on the reserve chute. When the primary was packed, we accidentally let the secondary tether get on top of the primary. When the chute snapped tight, it threw the secondary tether up and broke the door.

It is an easy fix for both the door and preventing it from happening again. We had made molds of the doors in case the became damaged and have figured out what we need to do to separate the tethers.
I almost never wake up cranky, I usually just let her sleep in.

Offline robfrey

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Re:
« Reply #912 on: October 03, 2013, 09:27:29 PM »
Thanks Rob
Couple more questions if you don't mind please:
How thick is your body shell? I have Bidirectional cloth (can't remember what weight) and no glass experience.
I'm not sure how many layers to put on, figure if I get a decent resin to cloth ratio and end up about the same thickness I should be close.

How does the piano hinge go working on a compound curve?

Thanks
jon

Layup schedule changed as to what piece we were working on. Fuselage, wing and wheel pants are completely different. I recommend you talk to Blue before ordering more material . He is a composites engineer and maybe one of the best for this type of work.
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Offline bbarn

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Re:
« Reply #913 on: October 03, 2013, 09:50:01 PM »
The piano hinge will not work on a compound curve, it will barely work on a simple curve. The locations that we place the piano hinges (canopy and both chute doors) were straight (only slightly curved) runs. It will not take much diflection to make the hinge non-functional.
I almost never wake up cranky, I usually just let her sleep in.

Offline interested bystander

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Re: NACA 66 Special A/BGS
« Reply #914 on: October 03, 2013, 10:34:00 PM »
Nahh, leave the hinges up a bit . . . VORTEX GENERATORS!

I've used that for about 30 years to bamboozle folks!
5 mph in pit area (clothed)