invertmast

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Rudi,
Thanks for the clarification on the loads. Even if assuming a 60lb wet weight, 265lbs divided by 60 = 4.41. What am i missing here to where you and oli are finding 6g failure rating?
even so, a 6g max load rating is still insufficent as far as i am concerned.

It will be interesting to hear FEJ comments on the failure.

Wap4life

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great thread I'm learning a lot.

invertmast

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Well said jeremy!

Jgwright

Rudi

I have only just picked up on the recent posting on this thread. I am sorry that your beautiful looking F14 failed its test. However it is a great benefit to others including the manufacturers to have your full disclosure as they will be more aware of the loads these planes should be able to meet. Those who say that 6 G is adequate loading should fit a Eagle tree recording device and look at the results. A moderately heavy landing with no U/C damage can easily reach 5 G. I agree that an aerobatic plane should have easily met 8G. Having said that the F14 with its wing pivot arrangement is a very difficult subject to meet a weight test.

Looking on the positive side using your skills you have repaired the wing and shown others how it can be done, you are to be congratulated and I look forward to seeing it fly.

John

Shaun Evans

RW,

That's a great fix (and fast, too) on your wing. You might have written it, but what's the material you used for the spar?

ChrisPetersen

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Honestly after seeing the inside of the wing and the improvements the gentleman from Germany did I am pretty shocked that that's all there is on the inside. I plan on doing the same reinforcement. That said. I have watched with obvious interest on you tube and in real life these Tomcats fly and not once have I witnessed a wing failure in flight. Can it happen? Hell yeah! Has it? I do not know. Mr Hinton has probably flown his harder than anyone I am aware of and not had a problem. He did reinforce the center section but I don't think he did anything to the wings themselves.
Jeremy is absolutely correct this is not a j3 and I should have kept my opinion to myself . But as a person who has built one or more accurately assembled one I don't have the confidence in the model to do anything more than basic aerobatics.
Like I said, but apparently did NOT convey . It is what it is. And it's a far cry from an aerobatic machine. I wish it was.

readyturn

My Feedback: (9)

Double post

Rici

readyturn

My Feedback: (9)

You need to consider the 30% lift contribution of the fuselage..... Assuming the max fuel weight of 60 lbs and a load factor of 6 g's, this would give a total load of 60(6) = 360 lbs. Take 30% of the 360 lbs, this then gives 0.3(360) = 108 lbs. Take that value and subtract it from the total required lift will then give the wing lift contribution. This value is 360 - 108 = 252 lbs, next divide it by 2 to obtain each wing's lift.  Again this value would be 126 lbs. They used some conservatism and used 132 lbs.

For the static test; however, I would have thought that you would want to include the lfit distrubution of the fuselage to prove out the attach pivot point.

Thanks for sharing all the info as I have been looking at getting this aircraft too.

Rick

invertmast

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Ahh ok, i was not considering the fuselage as a lifting device..

FenderBean

IS that f-14 made out of the new lighter material? I looks like the honey comb stuff.

rwwinter

The new spar is made out of honey comb prepreg an carbon rovings. The side parts are 2x 180gramm glas fiber and the op and bottom cap is out ov carbon rovings (4mm high). I was not able to calculate the spar, everything is now slightly oversized.

The complete weight penalty after repair and reinforcement is less than 300gramm

The complete plane just "survived" 90kg load on each wing yeah!!! Horrible to see the 180kg sand on the plane. Video will follow later.

Hoping to do the maiden this week.

Rudi

invertmast

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it looks like their typical laminate of carbon/fiberglass over balsa/ply to me

readyturn

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Rudi,

Just thought, you might share your improved F-14 with FEJ so that they may think about a production change!

Great job on the mod!

I did some looking around and it looks like the full scale 5.5 g's. If that number is not correct please, someone, chime in.

Rick

invertmast

My Feedback: (23)

I'll have to look in my research material for the max g loading, but 5.5 sound a little low..

According to the Flight manual:

68,000lb aircraft symmetric limit = max 4.6 g's
58.000lb " " = 5.5
53,000 lb " " = 6.0
50,000 lb " " = 6.5

FenderBean

Your right I saw the mod piece and it looked like the new honey comb, well it does look like a simple fix. Since the German mod worked. Has anyone talked to Lowell about having him push the issue?

mtnflyer14

Your numbers are correct - max symmetrical positive G was 6.5, negative was 2.4, I think. But who would want to pull (push?) 2.4 negative? I did pull 8.3 positive during guns defense training and there was no structural damage found in the maintenance inspection.
Sure am looking forward to reading about how the model flies!
Regards,
Gus

VF84sluggo

My Feedback: (55)

Gus, if I remember right, up to 8.2 was a 'mild' over-g. I think maintenance pretty much looked for loose fasteners and panels, and for fluid leaks (beyond the normal amount )

invertmast

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I vaguely remember reading a story from an F-14 pilot that a squadron member had pulled a reportedly 10 g's in the F-14 and the airframe only suffered minor damage.

VF84sluggo

My Feedback: (55)

Yep, 10 g's has been done. Might have caused only minor damage to the jet, but caused much wailing and gnashing of teeth in maintenance control. The jet went 'hard down' for a major overstress inspection, and the overall longevity of the airframe was reduced.

invertmast

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yeap, thats pretty much what he said. They were on deployment in the gulf when it happened.. maintenance guys weren't happy i'm sure.

VF84sluggo

My Feedback: (55)

But on the bright side, shows the airframe was pretty tough! At the 'max permissible' 6.5g load, there was a good buffer between that and the g-load which would cause the jet to come from together to apart

That might have been optimistic spin on the event that the offending pilot offered the Skipper before he got his face ripped off!

invertmast

My Feedback: (23)

Their definitely was a reason why the only thing that would come out of a F-14 wreckage essentially in-tact was the wing carry-through spar

VF84sluggo

My Feedback: (55)

That's a fact. That titanium box beam was amazing. A Tomcat got flown into the ground down at Dare County during a demo practice. The recovered pieces and parts were layed out in the hangar. The destruction was incredible...except for the box beam. Clean off the mud and it would have looked like new. Not a dent on it.

rwwinter

The video of the second static load test con be found here:

[youtube]http://www.youtube.com/watch?v=WDI1k-zRCAw[/youtube]

It's uncut and not censored

Rudi

rcjets_63

My Feedback: (4)

Did you see the beer on the workbench to the left? Those Germans sure know how to static test!!!!

So, with 4 x 4.5Kg bags + 3 x 25Kg bags = 93Kg per wing and it survived. Much better than a failure at 60Kg. And it was such a simple fix to correct such an obvious design flaw. The big question is if the factory will incorporate the improvement into production (like should have been done when Olivier sent them the audit back in July 2009).

Well, will they?

Do any German speakers out there know what the big cracking sound was at 5:28? Was it the mechanism?

Regards,

Jim