Hello guys,
After the recent thread regarding the F15, I decided to really inspect the wing construction of my Liberty. I plan to fly this jet fast and hard, as such I am checking everything as I build the airplane.
So today, I cut some holes in the wing root (or rather enlarged them) to see what was in there.
Well, I was pleasantly surprised.
First of all, BOTH wing spar boxes are plywood. Further to that, the wing root, the outer spar rib, and the next rib I can see are all plywood. There is what appears to be carbon fiber tow laid up into the main wing spar through the wing, parts fit is good, and the wing looks to be VERY strong.
There is one issue that I have addressed with James, it is an easy fix for the factory and was an easy fix for myself.

The wing tubes are bolted into the wing through the plywood spar box. That is fine except that they have put a bolt clear through the spar right at the wing root, perhaps with a carbon tube this isn't that big of an issue, but I have seen many aluminum tubes fail with holes in that area.
I fixed it by removing that bolt and gluing in a solid carbon rod inside the wing tube, it will never break there now, and I have no fear that the wing spar box isn't strong enough.
The carbon rod I put in the spar was a .250 X .200 solid shaft, since that obviously doesn't fit in a round hole perfectly, I glued balsa to the 4 sides and sanded it round to fit in the spar. I then filled the spar with polyester resin mixed with carbon fiber dust, and pressed the new shaft into the spar. The solid shaft did touch the original spar on all 4 corners, so the balsa is simply there to fill in the space.
The following pictures were taken with my camera phone so they aren't great, but the spar box and ribs are definitely all plywood.
It appears FEJ's is listening, it's unfortunate that the F15 in the other thread was lost, but from reading the end of the thread, FEJ's has made good with Uwe.

Enjoy the pictures.

Yea baby!! Cool beans!! Bam!!
My Man, you can do Mark 2 now Goose!! Bam!!
That guy is funny!
Scott

LOL, nice Scott, when you gonna order up a Liberty? :P

Funny how a post can be started that has the word WARNING in the title and it's bad news, everyone jumps in and starts making comments, then people ask how the quality of newer kits is. So then this post comes up showing something GOOD, and nobody comments. I know that in large part human nature wants to witness the bad and make the negative comments more than positive (which is to bad but seems to be the way it goes).
Oh well, at least I can fly this plane feeling good about the construction

LGM
I for one am watching this thread with interest as I have been contemplating a Liberty L. Just waiting on first impressions like this, so I thank you for your efforts. Generally if I don't have something constructive to add I tend to butt out.

Hey Steve,
It's all good I am not looking for huge responses, I just find it funny how a thread that says warning in the title and is about something bad will warrant so many comments from the peanut gallery but a thread reporting something good about the current company of the week doesn't seem to receive the "glad to see they are changing" type comments.
I am very impressed with the construction of the Liberty, lots of carbon fiber, plywood in the right places, if we could get the Liberty with skin hinging and flex plates for the landing gear it would be close to perfect!
Jeremy

yeah amigo, but i think the greater awareness which is being generated among us modelers is to not simply treat these jets as erector sets and expect them to last for hundreds of flights. not always the case obviously as some have had a good run, but i'm pretty sure we can all agree that quality has varied from kit to kit depending on the batch.

perhaps a caveat is warranted, I should say "a recent history or track record" has created the awareness Oliver et al have brought forward.

I certainly appreciate your time and effort to take pix and describe the (+) qualities of your current project.

cheers
buck

Jeremy,
Dont make me send our good buddy ricky over here Anyways.. i got to thinking about your both thru the wing tube last night. personally, i would probably replace the entire tube. Mostly b/c over time (with your mods it would probably last forever) what flexing it does get, it will slowly put stress fissures where the holes were (especially if they were not deburred, which is probably a very high possibility they were not). Just something that kinda lingered in my head all day after reading your post.

Jeremy,

Thanks for posting what you found on FEJ's Liberty model. And your easy fix you came up with. Now what do we do with the FEJ models built using the construction design on the F-15 that failed??? ANd if the F-15 constructon was changed, when did that happen????

Ditto below:

Hi Buck,
You are correct. It's to bad that this bad stuff has to happen, unfortunately, and I'm sure you'll agree with me, the average jet modeler has become very complacent in recent years. When we flew ducted fan, there was a maintenance schedule to go through after each flight, and a bigger one at the end of each day. When turbines first came out, everyone watched their start up area, everyone monitored the engine with a GSU, everyone had an extinguisher right next to them. When the first Chinese ARF's were on the scene, it didn't take threads about crashes to make everyone inspect the jet after each flight or during the build.
Unfortunately, (or fortunately I suppose) today the jets have become so very easy, people take them for granted that they will simply work all the time. To many people do treat them like "erector sets" and expect hundreds of trouble free flights. I look at my Kingcat, it is a great airplane, I haven't had any problems, but I do still make sure to check on things after each days flying. I've found bolts that loosened off on my landing gear, I've found bolts loose on my gear struts, I've found servo's that have worn, etc. It's just regular maintenance stuff that should be done, but not everyone does it.
I keep watching at different events I've attended and have noticed that while there is usually a fire extinguisher in the start up area, not many modelers have one right next to them during start up anymore, I've seen many guys who start their engines with all hatches on, not monitoring anything during start up and very unconcerned about what could go wrong. I think sometimes that it's the overall attitude or even maybe laziness on some modelers parts that is just as dangerous as an airplane built incorrectly, some of these crashes perhaps could have been 100% avoidable if the modelers in question (and I am NOT pointing fingers at anyone, just an hypothetical scenario) were still as conscious of the maintenance in their models that they were 7 or 8 years ago.

Thomas,
I thought about replacing the entire tube, but with the inside filled solid with resin and a solid carbon shaft, I know my tube is not going to be the failure point. I also made sure the holes that were drilled for that bolt were completely filled with the resin as well. I think that the carbon tube is probably not as critical as if it was an aluminum tube being that the carbon tube is multiple layers or strands of fiber, where an aluminum tube once it begins to fracture it will not stop at the next fiber, it will continue around like glass. I'd venture a guess that the wing would fail long before my modified tube does, glad the spar boxes in this wing are strong

Jeremy,

I do think that its good that the construction on the Liberty is looking better than their earlier attempts. However, I still wonder if its "good enough." The problem is, I don't really know - because I haven't designed a bunch of successful jet kits. Unfortunately, I still don't feel that FEJ knows if its "good enough" yet either because they don't yet have experience designing a bunch of successful jet kits. Their admission that they "learned a lot at Jetpower 2009," while a positive step, reinforces that feeling. Is it good that a company that is actually selling some of the largest jet models out there still isn't sure how to build them? That's somewhat scary to me... I'm also not sure when, or how, they've changed the construction on the F-15 to address the issues that were brought up in the other thread - they or their "reps" have never addressed the issue publicly to let us know.

The bottom line for me is, having bought two of their early jets, I will not buy another until I see a *lot* of them flying - primarily out at events where all can see what the results are. So far as of last year, I saw my F-15, one FEJ 1/8't F-16, Andy Kane's 1/7th F-15, and Rex's F-18. From those examples, I'd say that the results are still very mixed...

Bob

Hi Bob,
I agree, I haven't seen many FEJ airplanes in person, from what I have seen, the Liberty is leaps and bounds better than the earlier stuff. I plan to fly my Liberty and fly it fast and hard, time will tell. As such, I am going through this airplane nose to tail and checking everything!

couldn't have said it any better amigo. my observations are exactly the same.