1/2 time show

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how much is 60kgs in pounds

1/2 time show

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I have jest recived my F-14 and I do not belive I will not do the wing test! http://www.youtube.com/watch?v=ZgZwOyCndY4

Shaun Evans

Hi,

True, but I think a lot of times people think these planes have to be lighter than they really do to fly properly. The bigger these things get, the higher the relative wing loading numbers can be without them falling out of the sky like a rock. I've seen one of these fly, and it was very heavy...but didn't fly or land like one might imagine a 'heavy' plane might. If the owner was in a place where there wasn't a 'legal' consideration (like AMA) regarding weight, then I wondered what the concern was.

FenderBean

This was exactly what someone (Lowell) told me and it makes since. Lots of factors that play into a successful design. It could possible make something fly totally different when you take the same wing loading and make it lighter. May not fly as good or it may.

ddennison

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60 kg = 132 lbs
DD

rcjets_63

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Matthew 21:16

EagleJC

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From what I heard, it is about 90kg on that wing, not 60kg
Company also can do I-beam bar on wing construction if they want to do this test.
James

Shaun Evans

Hi,

Did you hear something that contradicts what shows in the video? In other words, that they loaded more weight than they reported/showed? Also, with regard to the I-beam, how would it be connected to the pivot? I guess that's where I'm the most confused: I can't tell from the video or any photos I've seen how the wing spar structure connects to the pivot.

ChrisPetersen

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While I understand the desire to load the crap out of the wing to see if it will break ,, I have to say I have one of these Tomcats and I understand that it is what it is. A heavy replica of a heavy warbird. Its not a 3D machine or even a pattern ship. If you are looking for an every day flyer this aint it! I am gonna stick to a very scale flying style , I dont think alot of yanking and banking is gonna do this bird any good . Save the high Gs for a flash or a bandit. In my personal opinion and from building this bad boy if you treat the plane respectfully and sympathetic to the airframe you shouldnt have a problem.
I visited with Shulman after he flew one at the best of the west last year and he basically said it was not the easiest to fly plane. But HOLY COW it was cool!

1/2 time show

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Verry well said! I agree

olnico

Completely wrong ! Do you realize how little 6G is? A smooth scale aerobatic maneuver in turbulence will bring you over 6G on a jet model.
Any smooth scale flight will exceed this value unless you only fly landing circuits at 100 mph.

Additionally this is not a matter of agreeing or not here: it is a REGULATIONS matter.
Go and say to the AMA that your LTMA-1 model will have a wing failure at 6 G and wait to see what the inspector is going to tell you...

In most countries of the Europe, an aerostructure like is not legal to fly because you have to demonstrate a reasonable flight envelope.
Our German friends did not do this wing loading test for the sake of it: it was legally required to demonstrate +8/-4G. This is a very reasonable value BTW. I pull 40G from my Phoenix in hardcore maneuvers like full speed snap rolls ( recorded on the Jetcat GPS ).

Once again I reviewed Reza's F-14 when he received it and sent a complete audit report to FEJ about this plane a year ago. They obviously did not do anything but put it in the bin, as usual.
The wing clearly failed at the pivot junction point. An I beam structure will not change anything on that matter since the spar is strong enough for the job as it is made by FEJ. A complete redesign of the wing pivot system with a proper in wing carbon junction box will be required here. I discussed the matter many times with Invermast and his F-14 will be up to this task.

olnico

James, look at the video and read the weight value on the bags. 25 x 2 and 3 bags of 10. 80 kgs.
However the wing failed before this value was reached. So the max load of 60 kgs seams to sound realistic.

olnico

BTW at 34 kgs MTOW ( 75 lbs ), this plane is under LTMA-1 regulations.
http://www.modelaircraft.org/files/520-a.pdf

Max wing load: 100 oz/sqft

The philosophy of the AMA regarding the flight envelope is to demonstrate it by a dynamic test, as opposed to loading static tests required in Europe.

"It is important that the model aircraft is flown to the full extent of the flight envelope appropriate to the
aircraft, including full speed level flight, minimal speed level flight in a dirty configuration,
and recovery from a dive or split S maneuver."

The only static test required is made by hand:

"The inspector shall verify that all flight surfaces (wings and tails) are reasonably stiff and solidly
attached to the fuselage. With the fuselage held in place (by hand or mechanically) the inspector
should hand load the wing from the tip, applying both vertical loads, up and down, and twisting
loads, leading edge up and down. The intent is not to determine the ultimate strength of the
model, but that under moderate loads there are no unexpected motions, and that there is no
evidence of failing joints. The tails shall be tested in the same manner."

However, given the amount of vertical play in the wing incidence system on the plane that I reviewed, I believe that it would not qualify for these requirements neither.

rwwinter

The maximum load applied to my wings was 65kg. 2*25kg (white sand bags) and 15kg total in the grey ones.

Having now finished the reinforcement and repair I built a jig to test the wings indepently from the fuselage. Ijust applied 90 kg to each wing. NO failure now .

This evening we will do the complete test (wings and fuselage)again. Cross you fingers... I will post a new video thereafter.

Concerning the tests I need to do with the plane to get the German certification here a short summary:

Static tests:
Wings up to +8 -4g (maximum assumed lift of the fuselage accepted by the authorities is 30%) meaning 90kg on each wing for +8g
Tailerons (15kg)
Rudder (9kg)
Swing wing system must be fully functional with 4g load applied

In addition all movable surfaces have to be load tested to simulate gust and maneuvre loads.

Flight test::
Plane must be flown the complete flight envelope including
ALL aerobatic maneuvers intended to fly.
One engine out (simulated)
Full power 10° dive
Stall

Flutter may not occure during the complete test.

A flight manual including wiring diagrams, load calculation,emergency procedures etc. etc. must be written.

.
Concerning the limitation we have a wider enevelope. There is just one class of rc models whichcan be certified in Germany. The weight is 25kg up to 150kg. Maximum speed in uncontrolled airspace is 250kts.

What I would like to say is that FEJ CAN'T build planes to meet all requirements in the wolrd. They simply can't know them. BUT a wing should hold more than 6g and the connection of the swing wing pivot to the otherwise fine built wing is horribly bad.

Just imagine such a bird would crash into a crowd of spectators with a broken wing [X(]

Rudi

1/2 time show

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We have all seen these fly on youtube. have any of these wings failed in flight?

olnico

Yes and FEJ is fully aware of this since the 20th of July 2009. Date at which I send them a full audit report, including this specific point.

rwwinter

I simply don't know.

I saw Mark Hintons plane during the JetPower Fair and it flew just perfect. BUT I even haven't seen anybody flying maneuvers like the original.

All the FEJ F-14 I saw (live and via YouTubel) have been flown very very carefully. Not fast and no G loads applied.

Beside the needs of certification I would like to have a plane which is capable to survive a not perefctly flown loop...

Rudi

olnico

Rudi, by the way, thank you for taking the time to posting here about your findings.
Very informative and useful for the community.

rcjets_63

My Feedback: (4)

Oli, thanks of the background. Based on FEJ receiving your audit in July 2009 and still making statements today discounting the test, it appears your report fell on deaf ears. Perhaps they know that the wing is strong enough because their business plan says so.

This was a valid test to meet a real regulation. One can't discount the results just because the result wasn't favorable.

Rudi, good job with the test and I'm glad you were able to get the wings to pass the German 8G requirement. Good luck on your maiden.

As for how easy this bird is to fly.....

Shulman doesn't know what he's talking about. After all, he's only been flying jets for about 15 years or so including some of the best and largest models in the world. He's won Top Gun many times. He worked for BVM (engineered to win) for over a decade, and currently holds the world record for the fastest R/C turbine model. So what!

Here's the real "skinny" on the FEJ F-14 as recently reported by a jet newbie....

Regards,

Jim

rwwinter

Pictures of the NOT damaged wing after opening for reinforcement:







Pictures of the dameged wing:









As you can see there is no sufficient connection between the wing pivot and the spar. The wing failure started at this point.

I modified the wing as following:












Rudi

invertmast

My Feedback: (23)

Assuming a 60lb "wet" weight (which is probably lower than what it would be) 60kgs = 132 lbs roughly, which is a 2.2G load. That is way under what i would expect that structure to hold. I am expecting my model to hold a 10G continous load assuming a 80lb wet weight.

rwwinter

[/quote]

Assuming a 60lb "wet" weight (which is probably lower than what it would be) 60kgs = 132 lbs roughly, which is a 2.2G load. That is way under what i would expect that structure to hold. I am expecting my model to hold a 10G continous load assuming a 80lb wet weight.
[/quote]

Small correction... 60kg have been applied to each wing totalling 120kg (265lbs) . Keep in mind that the fuselage generates lift too (30% assumed). I think the failure accured at about 6G load...

Rudi

olnico

I think the failure accured at about 6G load...

Rudi

[/quote]

Yes, that's what I would say as well.

siclick33

Maybe FEJ can clear this up by stating their calculations and assumptions and confirm what they believe the wing should be capable of withstanding and what their tests revealed.

LGM Graphix

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I am not making my following statements in regards to FEJ's, I am making it in regards to structural failures, model designs, and in response to this quoted statement.

1. This is an F14, not a freaking J3 cub! Even if you are flying SMOOTHLY with an F14 you are going to hit fairly high G loads.

2. The best pilots in the world will run into a situation from time to time that requires a harder pull on the elevator, do you really want a jet that is stressed just enough for smooth flying?

3. Scale flying with a Tomcat isn't just simple circuits, it's rolling reversals, split S's, loops, etc, all maneuvers that will pull higher G's than a basic landing circuit.

When your jet goes through a turn, it accelerates the whole time.
The amount of Acceleration is equal to the velocity of the aircraft squared divided by the radius of the turn.

So if your jet is flying at say 200mph, (293.334 feet per second) and your turn is a 400 foot radius (which is pretty realistic), acceleration is 215.11fps2
The acceleration due to gravity is 32fps2, so 215.11fps2 / 32fps2 = 6.72G's!!!!!

Loading a wing to 8G's should not be unreasonable at all, and at 8G's, it should still hold without any creaking, groaning, *****ing or moaning. 8G's should be it's safe zone with a good buffer outside of that.
As for statements like this airplane is not an everyday flier, why shouldn't it be? From a stress point of view to the pilot it may not be, but every aircraft we build should be built like it's an everyday flier and be able to take the loads of flight over and over and over. Even if you don't expect it to be an everyday flier, I'd still be expecting any airplane to be able to take the loads needed during any flight for a full scale aerobatic schedule which with any fighter jet is going to include some fairly high G loads. Further to that, what happens when you are coming out of your split S and realize that you should have started 100 feet higher? Do you say to yourself, "I'd pull harder on the elevator, but my wings will fold?" Do you say "I guess I'll just fly it into the ground since the wings will break anyways" Human nature is going to make you yank the elevator to try to save your model, I'd like to know that if I hit 10G's or more in that situation I have a chance of the airframe holding together to save itself.

Again, I'm not posting this as a shot at FEJ's, this is a very complicated model and I'm sure these very reasons are why Skymaster and Fei Bao STILL haven't released their Tomcats after such a long time. Any manufacture producing a complicated jet like this will face these problems, but in this instance, with such a small structural area, I do think overbuilding is the order of the day.

Just my opinion.