FEJ planes: list of points to watch closely
 

OK guys,

I can see that more and more people are loosing FEJ planes.

So here is a list of points to watch closely on FEJ planes when you buy a new kit or service it.

This is not a bashing thread. So please do not use it to criticize FEJ products or become unpleasant/rude.

Please note that I am not linked to FEJ by any means, I am just a normal customer. I have never lost a FEJ plane and never had any problem with the company.
I have nothing against FEJ and I consider the product adequate for the price offered IF MODIFIED CORRECTLY.

I have an aeronautical engineering degree and am working in the airline industry. This drives me to think conservative and modify the planes accordingly. Additionally note that I have not crashed a jet for the past 18 years ( apart for the Tamjets A-4 due to a Spektrum system design problem ). Al the jets I have built during this period are still in flying state. So I think that my approach to flight safety and safe building is sound.

This list is mostly intended for people with a limited building experience who want to fly one of the following planes reliably. Note that since the FEJ products are all made with the same techniques and philosophy, this would probably be applicable to the other kits as well.

1/7th scale F-18F:

The first series of wings were made of a red Airex foam sandwich with no inner layup that was really weak. If you get these wings, discard them and get new balsa sandwich set of wings from FEJ.
The wing spars are balsa wood and wrong grain orientation ( horizontal ). Keep a close look at them from the servo bay and do not pull too many G's from them.
The horizontal stabilizer tube is a bit thin and flexible to my taste. Keep a close look at it.
The horizontal stabilizer tube gluing has been a problem on the recent 1/5.5 scale F-16. Since there is no way to verify it, I recommend to drill it twice and put two additional steel torsion pins across the thickness.
The horizontal stabilizer system bearings have a tendency to get some play. Lock them with bearing loctite and keep a close look at them.
The horizontal stabilizer servo setup is wrong. The servo will not produce enough torque to move the elevator in all the conditions ( DS 8711 ). This might results in a faster than normal servo wear. The solution: either go for the 8711 HV and direct lipo feeding, or adapt the pull-pull system to get more torque ( refer to the F-18F thread or my RCJI article )
The main fuselage formers to wing and engine holding formers and plates are too weak: double them with 5 mm aviation grade plywood.
The main former bridge shape is appropriate but the plywood used is a bit soft. Needs to be properly reinforced with carbon fiber or re-cut ffrom proper aero plywood of the same thickness.
The main gear assembly has a tendency to wear out quite quickly: the retract walls need to be inspected and changed on a regular basis. I have been working on a different design of the walls and will come back to you if it proves reliable. Give me another 4 months...
The main and front gear will break the formers and gear plates as well as fuselage layup after a few hard landings. They need to be mounted on carbon flex plates. Have a look at the F-18F thread for a complete description.
Then back of the fuselage needs to be heat proofed to protect the rudder and elevator servos as well as their lines.
A lot of tailpipes produced by FEF were dangerous. Check for:
. thickness of the inner wall ( should be 0,2 mm ).
. spot welding done correctly, especially around the split,
. the mounting tabs should be welded to the inner wall, not the outer wall . This is especially important since the outer wall is cigarette paper thin and cannot assure a proper centering of the tube. A non centered pipe would induce more constrains to it and overheating in some areas with possible failure.
. Check that the inner wall stops at least 1/2" before the outer wall on the back end of the pipe for a proper venturi/cooling effect. Some pipes were flush.
Make sure that the wings have a positive OAO when the plane is sitting on the ground before the maiden, or you might have some surprises.
Check all the air rams for leak free operation. If you see a leak in a door ram: discard. If you see a leak in a gear ram, open it, remove the o'rings, wrap some teflon band in the ring groove and re fit everything.

1/5.5 scale F-16


The wing spars are balsa wood and wrong grain orientation ( horizontal ). Keep a close look at them from the servo bay and do not pull too many G's from them.
The horizontal stabilizer tube is too thin, too long and flexible to my taste. Keep a close look at it.
The horizontal stabilizer tube gluing has been a problem on 1/5.5 scale F-16 resulting to at least one plane crash. Since there is no way to verify it, I recommend to drill it twice and put two additional steel torsion pins across the thickness.
The horizontal stabilizer brass tube assembly is sometimes badly glued. I strongly recommend to open the fuselage aerobrake pods from the rear and check the tubes gluing. The tube system has a tendency to get some play. This fact along with the flexibility of the shaft and possible poor gluing of the stabilizer make this setup unsafe. fill the brass tube will plenty of thick and sticky grease to minimize the play.
The brass tube gluing is critical. To be verified and reinforced.
The horizontal stabilizer servo setup is wrong. The servo will not produce enough torque to move the elevator in all the conditions ( DS 8711 ). This might results in a faster than normal servo wear/ slow pitch control. The solution: either go for the 8711 HV and direct lipo feeding, or adapt the pull-pull system to get more torque ( refer to the F-18F thread or my RCJI article )
The main fuselage formers to wing and engine holding formers and plates are too weak: double them with 5 mm aviation grade plywood. Pay a special attention at the rear main former that takes most of the landing gear loads.
The main former bridge design is not appropriate. The bridge side walls are too hight and do not allow a proper work in compression. Needs to be adhequately re-cut from proper aero plywood of the same thickness with a straighter shape.
The gear of the F-16 is useless to my knowledge. I am still waiting to see a proper mechanism with reliable up and down lock and strength ( I mean something that lasts more than 20 flights ).
The best solution so far would be to go for the Matrix gear ( when it will be ready )
Then back of the fuselage needs to be heat proofed to protect the rudder and elevator servos as well as their lines.
A lot of tailpipes produced by FEF were dangerous. Check for:
. thickness of the inner wall ( should be 0,2 mm ).
. spot welding done correctly, especially around the split,
. the mounting tabs should be welded to the inner wall, not the outer wall . This is especially important since the outer wall is cigarette paper thin and cannot assure a proper centering of the tube. A non centered pipe would induce more constrains to it and overheating in some areas with possible failure.
. Check that the inner wall stops at least 1/2" before the outer wall on the back end of the pipe for a proper venturi/cooling effect. Some pipes were flush.
Make sure that the wings have a positive OAO when the plane is sitting on the ground before the maiden, or you might have some surprises.
Check all the air rams for leak free operation. If you see a leak in a door ram: discard. If you see a leak in a gear ram, open it, remove the o'rings, wrap some teflon band in the ring groove and re fit everything.


1/7th scale F-14:

I have only just started to look at this plane. So I have only a few recommendations at this stage.

The wings are made the proper way ( vertical grain spars ).
However I think that there is too much torsional flexibility between the main sweep rotation axis and the back plate. This plate also exhibits some vertical flexibility.
All together the wings have some degree of incidence slop ( about +/- 5mm ). This will only worsen with time and I think that it should be addressed at this stage.
The aluminium cross braces do not go from one wing bearing box to the other. I would recommend you to go to your nearest machine shop and get a new pair made longer to be bolted directly to the bearing box.
Check the horizontal stabilizer system completely once again and secure the rotation tube gluing.

AT3

Main fuselage formers: they are made of cheap 3 ply plywood and it might be worth considering a reinforcement here.
Main gear area: to the gear on flex plates, reinforce the wing area with carbon fiber
Wing spars: they are made of thin balsa wood an the grain orientation is wrong. Will develop horizontal cracks due to the gear torsional efforts.
Elevator: setup the servos with an amp meter to make sure that they don't fight against each other.


This short list will given you a rough idea of what to check on these planes, and the additional work required if you want to keep them for a long time. Of course this is only my personal point of view on the matter. I am not a living god and I can be wrong as everyone else. However, once again these points are dictated by my model and aeronautical experience.

RE: FEJ planes: list of points to watch closely
 

Oly,

I have an AT3. What should I be looking at?????

Chris

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They need to hire you dude. This is info is money.

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I agree

The sad thing is most of the overseas companies will not listen to the suggestions...it is very frustrating.

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Hi Chris,

Can you come to me with the plane before the maiden ?

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Spending a little more cash & buying a jet of better quality:D.

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Hi vet. Most of this information is on RCU already. But lost among 4 or 5 threads.
I hope that this synthetisation job will help some modellers.

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Oh yes it is...

I am aware that this information will become bad publicity for FEJ. Keep in mind that all this information has been known by them for months now.

I am not really happy to publish this kind of "product service bulletin" like Boeing call it. But I believe that it had to be done in the interest of the community.

FEJ claims that some of these points have been corrected, some are irrelevant.
Regarding the irrelevance, it is all a matter of "how long shall the plane last for"? I am a big fan of making them last as long as possible given the amount of money invested and the potential threat of an in air failure. This is why I am so picky when building my planes.
But what about the plane produced before the feedback ? Who ever got them ? Are they flying? Are the guys aware of these points ?

Guys let me know what you think about this post and if you believe that it shall be here or not.

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Oliver.. I praise your efforts and dedication! What you do can only help make this hobby safer and better for all of those involved. You also manage to do it in such a good way! I have zero interest in FEJ's as a product, but do worry about how their shortcomings in design and construction ( Especially now they seem hell bent on making bigger and more complex models ) effect this hobby. So from me.. thankyou!
Regards Al
Oh and as to wether this post should be here or not.... Hell Yes! I think it would be appropriate that it went on their web site and came as a printed sheet which each kit sold. A problem that is ignored is the most dangerous type.

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Thanks for your valuable feedback Ali. I do take it very seriously, as all your feedback.


When I refer to the Boeing "service bulletins" this is exactly what I mean.

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Hi Oliver
Personally, I very support such a great post and I think that will be of great help to all.
Would be very welcome if they also apply to other companies(SM,...) gave a description of the failures .
p.s. My English is such- such I hope you understand


Regards Peter

RE: FEJ planes: list of points to watch closely
 

Well RCU is a wild place in a certain way. These kind of posts tend to spin out quickly and become useless.

This is why I want to keep this one objective, professional and constructive as much as possible.

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good advice amigo. although i've never owened a FEJ airplane either, I would use the info you provided toward any ARF manufactured jet.

I'm sure we could all agree there are precious few manufacturers where we could simply add water to the box of parts, shake, stir and pop out of the oven ready to fly with no worries. As is often stated in the business of aviation, "safety is everyone's responsibility"

nice work

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Also and to keep this post perfectly objective. I would like to add the following:

The guys who make the layup at FEJ are really skilled. I have never received a kit that was badly laid up ( although some have complained here about that fact ).
Although there has been a spar grain issue, I consider that they make really good quality wings on their big kits.
The paint quality is good to very good.
The planes have very nice flight qualities.

I have bought quite a few kits from them now and will continue to do so.

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Any points to watch for on the 1/7 scale F-15? Thanks for the information!

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Good info Oliver. I wish someone would have posted this before my F-18 went down. Hopefully others can benefit from your information. I am kinda shocked at the level of mods that need to be completed for the jets you list. Even for the later revisions. I am hoping the F14 works out good for folks. I really wanted one but don't dare this early stage of developement. My FEJ F-16 (1/8) airframe has proven to be very flight worthy with over 60 flights on it.

Like you said, I think some of your recommendations would apply to all manufacturers (ie the grease to reduce slop).

I have never heard of bearing loctite. Do you mean just loctite the bearings with non perm loctite? Is this available at auto supply stores?

Lastly, I think, in the interests of safety, a generic (not calling out any factory) thread that goes over some of the basic building mods and points to check, that would apply to all manufacturers would be beneficial to add to this RCU forum as a perm sticky.

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Man am I the only Guy who Likes their Birds? I have Nothing bad to say I think they produce Great Birds!
Rick in Denver

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Ok now, who has the cojones to do a similar thread for Skymaster kits?? :D
C'mmon I know you are out there! Come out of the closet now! [8D];)

Good job Olnico!! Im an Aero myself and I just don't believe the crap that some kits are made of. Common sense guys, common sense!!

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Oliver,
Thanks for the in depth list of things to look for in a FE jet. Although I don't own one of their jets your post would be an aid to me and anyone building any ARF.
Thanks again.
Jose

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On the large 1/5.5 F-16. Mine has several VERY dry fiberglass areas that need additional layers of cloth in the fuse. They are so thin that it can't be handled without breaking them. Ill have to go threw the entire fuse. and It is only the fuse.

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Really??

Well, that's all I need to hear. You've got my attention. Teach on....

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How many do you own and have you flown???? From what I've seen, none...

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Olivier,

You have done a great job at presenting the areas that need attention to on the FEJ 1/7 F18F, 1/5.5 F16 and the F14, and have done so in a positive and informative mannor. It is this positive and professional process of presentation that helps each modeler improve the longevity and safty of their investment.

I think it also allows ALL manufacturers a glance at how to improve the construction and safty issues associated with turbine jet manufacture.

Andy Andrews took a lot of heat from his experiance, but the end result was we all learned a lot more about how are pipes need to be made, and improvements soon followed. Listen Folks, we all learn and FEJ is learning also. I have flown 3 FEJ Jets, and after the necessary mods were done the Jets do fly very well. FEJ is not for everyone, but they fill a low introductory niche to builders "Who know how to assess what needs to be improved"

FEJ has improved over the last 2 years, and will soon have even more improvements in construction technique. Case in point, my first F18F had the foam sheeting in the wings, and my second had really nice balsa sheeting. The second also had stronger and thicker wood formers in the fuse for added strength for the gear mounts.

We have shown before that pictures sometimes hide the truth, we compared Skymaster F18 wing to FEJ F18 wing. The skymaster wing had virtually NO inside formers VS. the FEJ. But skymaster's wings have performed very well. We could not see the building process, engineering that went into the skymaster wing, yet in comparison it looked weak, in reality it performed very well.

There is always going to be members here who have NO jet experiance, have no jets listed in there profile, have not built or have much understanding of Jets, yet feel perfactly at ease providing there "NEGATIVE" oppinions and comments to bash manufacturers and other members and have the NERVE to HIDE behind thier Avatar. This in itself hurts our Hobby more and more.

Thank you Olivier for all the correspondence you and I have shared, and keep up your excellent work.

Kevin Marks

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Damn jeremy, you ALWAYS beat me to the punch with this guy.. he is seriously getting on my last nerve.. Can someone please start a "top 10 list of people who need to be thrown off RCU for good?" LOL


Oliver,
Excellent info. Your build threads of the FEJ models as well as the unfortunate loss's of other peoples FEJ's have made my mind up that i would rather spend the extra money for the extra piece of mind. Either way, these threads have saved me alot of hard-earned money and headache's. Once i see that the are no longer making the same mistakes over and over, i'll consider one of their models..

Just wanted to say THANK YOU for all the information you have provided.

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Great work Oliver!!!




Ya'll should really leave Ricky alone. Just take a look at the F4 Phantom in his gallery.:D

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Couple months ago that F4 was being sold as a Bandit ;) haha

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LOL... you beat me to it again! :D

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NOW this IS what RCU is all about, Sharing information that makes the hobby enjoyable.
Great Job Oliver!!!!

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Thats the coolest F-4 i have every seen. Its a new series F-4. [sm=72_72.gif] Must of just came out. Who makes it? I like the rounded intakes and the single turbine configuration, saves gas and money. Cool!

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WOW!

After all of the negative comments/attacks placed on threads, attempting to impart essentially the same info, regarding individual FEJ aircraft, I am very pleasantly surprised to see this thread remain constructive and positive! Maybe this forum has finally turned a corner!:D

Well done Oliver!

David S

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Great post Oliver.

From what I have read and seen both here and elsewhere, you have a good knowledge of how a well designed model jet should be constructed. These facts should be in the public domain, so please keep them coming.

I personally do not choose to buy Chinese ARFs, (I like to build my planes and pay the extra for BVM), but I understand that they are a fact of life, and now fill a big segment of the market. These ARFs have made the hobby much more accessible, which is a GOOD thing.

I cannot however, understand how a company can release onto the market a product that will definitely fail, when operated as it was designed and manufactured by the factory. Relying on the consumer to fix design flaws is really not acceptable. R&D is the responsibility of the manufacturer, not the consumer.

So, should companies like FEJ be selling untested products into the market? I personally don’t think so. These models are sold as ARFs. Almost Ready to Fly. You should not have to re-engineer major structural components.

A bigger question might be; How will our regulators view an incident involving a model that has crashed, with a known design/construction fault. If there is property damage or personnel injury, there may well be ramifications for all of us.

For this reason alone, I would prefer if untested ARFs (as described in Oliver’s original post), were not on the open market…

(Hope this in not too negative David)


Roger

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Just let someone get Killed By any R/C Jet, Especially if it happens in the USA by a US jet... If the jet was made here, They might as well move to China...My .02

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Andy, I have some bearing LocTite...It has gap filling qualities and is permanent although a high temp heat gun will loosen it up...I'll get a picture of it tomorrow (11/11/09) afternoon...If you need some I may have a spare bottle laying around...I'll get back to ya tomorrow...

Kevin

Kevin

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David,
I agree! I pray the "frozen chosen" stay clear and let this thread be as it was started. Always good info from Oliver, Kevin and David.

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<span style="font-size:small;">http://www.rcuniverse.com/forum/js/f.../thumbs_up.gifhttp://www.rcuniverse.com/forum/js/f.../thumbs_up.gifhttp://www.rcuniverse.com/forum/js/f.../thumbs_up.gifhttp://www.rcuniverse.com/forum/js/f.../thumbs_up.gif Keep up the good work Oliver!!!!!!</span>

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Oliver,

You keep it going. This is the best way to get FEJ to listen up.

THanks for all the help.

Allen

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I just about finished the build of my F-18F "Bounty Hunter" that replaced the late "Diamond Back" I had before. I can see a marked difference in this newer one versus the other one which was one of the first 10. I feel there is much improvement with airframe weight and gluelines, formers being much straighter. After seeing the inside more closely from the wreckage of my other 18, it seemed more than adequate in structural integrity and would be more than enough for normal flight maneuvers. I lost mine from a flameout, caused by fuel starvation (caved in UAT) and missed the runway by maybe 20 ft. and went into very rough ground. But, as Oliver and others have noted before, the pure inertia of this heavy plane caused considerable damage to the airframe when it hit which I was not surprised of at all. I looked at wing structure, fuse structure, how the fuse joints at the wings and formers faired...and I was impressed! The only part I was a bit surprised at was the very back of the fuse around the vertical fins and Stabs was "egg shelled" but again, I think the inertia had much to do with that.

To say all of this, I have had several flights on the F-18 and with the input from Oliver, David Searles and Kevin Marks and a few others, this is a good airplane and they make good airframes IMO. I assume it is competative enough environment for them to take care of things "under the skin" BY NOW, that what I get in the box is then up to me to add mine and othersbuilding skills to make the package complete! I have had Airworld products with much less structure and was told by them "you Americans don't know how to build planes", expecting us to do things that they have not done.

Saying all of this, I like the FEJ planes. I am not an engineer like Oliver but I was a General Aviation pilot and can understand basic physics and load dynamics BUT I do depend on good threads to help me GET R DUN! These threads are my manual,so to speak. I like James, I like Eric, I like the pricing, I like the fact that while most of our "usual jet suppliers" have not been willing to go BIGGER, these guys have and have proven there is a GIANT JET market out there. I do not like EDF nor the smaller scale stuff.

I just bought the 1/5.5 F-16 in "Artic Aggressor" from my good friend "Whodaman" in CA. Can't wait! I know there are gear issues and wing questions...BUT, I am looking forward to the project and flying their planes.

Rex

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Rex,

Glad to hear you got another F-18F. So did I! My original Diamondback is still flying, but showing the wear from the original issues with the gear etc, but the jet flies great, so I got one of the new, improved versions recently, in the AETE scheme. I'll assemble it over the winter and have it ready for spring flying. You will love the F-16. Just make sure it has the new gear upgrade and then only use manual valves like the BVM HiFlow for the retracts and you'll be good to go.

I also built a 1/5 AirWorld F-5 this summer. For what you get and have to do, compared to the FEJ, I'll happily work out the bugs on the FEJ rather than spend the bucks & go thru an Airworld build again!

I'll be flying all of my FEJ aircraft at Buttonwillow next week. F-15, F-16, F-18F & F-100 are all up and RTF, only a few bugs yet to work out on the F-15, but still looking forward to it. I'll try to get some video posted later.

David S

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Dave , did you get FEJ's new "BIG" F18?? or is it the smaller one.

Thanks,
Billy

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Ive been using the FEJ 5in1 valve on my Skymaster 1/6th F-16. I took the manual valve I had the screw type and replaced it with 4mm Festo valve. Works fine. I wish they would make the gear lock automatically without the valve but this will work until they do. I forgot to open the valve last weekend on a flight. lol, at least the gear is locked down when that happens ha.

Andy

Andy