Mike James

Starting on the prototype fabrication.

I decided to make a new mold for the vertical fin, with two small changes... First, the new one includes etched lines for the rudder position, which helps us in production, and also helps builders keep these uniform. I also added the plate you see at the dorsal fin base on this mold, so that the bottom will be completely open. This keeps us from having to trim the part after molding, to fit the molded airfoil shapes on the fuselage.

The second photo shows the fuselage molds, prepped and sprayed with white primer. I'll be vacuum bagging the first fuselage tomorrow, and whatever else I have time for.

Mike James

Hi everybody,

The top fuselage half is done, and the bottom is in the vaccum bag now.

Bonus, from painting in the mold...
i was wondering how I'd align the gear door reinforcements (1/32" balsa) and the paint allowed me to simply make reference marks where they needed to go, then epoxy them in between the two layers of glass. Same procedure for the lite ply spinner ring.

I've also got one of the tailerons done, and some other small parts, such as separate landing gear doors, NACA inlets, etc.. Coming along nicely now, and this is a LOT more fun than sanding the plugs.

jetflyer

My Feedback: (5)

Very cool! Keep the pictures coming Mike.

JR Gautreaux

Mike James

Thank you, JR. There should be updates almost every day now, as I'm making parts.

Hey, I see you're making progress on your "Phoenix". ... Cool.

jetflyer

My Feedback: (5)

Mike,

I had too many projects going on at the same time. So I had to prioritize them so I could at least get something completed. So first on the list is to get my Super Reaper back flying again. But in order to do that I needed to make a composite fuel tank, which I'm in the process of doing. Weather has been a bit on the cold side and since I build in my garage I am waiting for the temps to get back around 70 before I do more epoxy work.

As for the Phoenix, I have my first full size mock up almost ready. I haven't glued in any formers yet or started getting it flight ready, but as soon as my Reaper is completed it will be full speed ahead on it. We have a jet even coming up at the end of April at Austin Texas and I would like to have the Phoenix ready before then.

JR Gautreaux

Mike James

Hi everybody,

Ta da!
Here's the first fuselage, joined and out of the mold Production fuselages will have the formers installed in the mold, and this one didn't, so I dinged it up a little getting it out of the mold. Still, it will be fine for flight testing, and it looks good. The second photo shows the (unpainted) hatches and the canopy test-fit. Everything looks good.

The last image is the prepped wing molds, and the wings are next, starting tonight. Latest updates are at http://www.nextcraft.com/j47_sportjet11.html

Closer all the time...

jetflyer

My Feedback: (5)

Mike,

Congratulations! Looks very good. I even like your Nextcraft logo embedded in the fuselage. Nice touch. Say, how did the line on the wings not get paint in them when you sprayed the molds?

JR Gautreaux

Mike James

I scribed the lines with a special anti-gravity tool, which repels paint, so that the molecules actually...

Ok, back to reality. The molds were entirely white. After the paint cured, I used a Sharpie pen and trace over my etched lines, to use as references for installing the internal parts. (Bonus, from painting in the molds) I just got back from the shop, and the first 2 wing halves are bagged and cooking. I'll do the other wing tomorrow. Been in the shop 15 hours today, and I'm about ready for ZZZZzzzzz land.

Another bonus of painting in the mold is that when you apply the first resin/glass layer, you can be pretty agressive with a brush. The paint is cured, and so you don't have to worry about tearing the more delicate PVA layer, which is on the other side of the paint.

Mike James

Progress this week...

Fuselage is together, gear doors are installed and functional, and I'm finalizing details to be sure engine access, hatches, etc., are all right. Internal parts are installed in the wing molds, which will be joined tomorrow, and pulled the next day. Latest updates are at http://www.nextcraft.com/j47_sportjet11.html which include some more photos.

Closer every day...

jetflyer

My Feedback: (5)

Sweet! Mike it is really starting to come along. I bet your anxious to get this one in the air.

JR Gautreaux

Flying Hog

Mike... Looking good. We haven't heard from you in a week, was wondering if progress was taking place. Keep up the good work.

Mike James

Thanks, JR and Bob.

Yep. We had an unusually-long internet outage, due to some local area problems.... almost 5 days. That's like 3 months, in internet years! Turned out to be easily solvable, and we're back up to full speed again, net-wise.

Lots of updates coming during final assembly, because those steps don't take as long as the plug/mold steps.

Flying Hog

Cool Mike!!!!! Glad to have you back!!!

kennyandannie

My Feedback: (2)

Great stuff Mike,

I am waiting patiently for the great news, " THEY'RE READY!!!!"

I'm sure you'll let us know. My Jett 90 is ready for a new plane, the F-15 just isn't doing it for me.

Talk to you soon,

Ken

Mike James

Here are the the first set of wings, joined and out of the molds. Good news and bad news...

Overall, I'm very pleased with the strength of the wings, and the way the skin hinges work, etc.. On the other hand, when I cut out the servo hatches, I found that some of my internal parts fit well, and some were pretty far off. (I sanded them too much.) So, I'll have to do a more careful interference check and refine those parts. Thede wings are overbuilt, so even with these errors, they're still flyable, and I hope the next set is production quality. It takes some "fiddling" to get it perfect.

Larger photos and latest updates are at http://www.nextcraft.com/j47_sportjet11.html

Magne

Mike,
Nice looking wing panels.
What is the finished weight of each panel?
Regards,
Magne

Mike James

Well Magne, I won't lie and say "4 ounces!". I'm embarraseed to say that the complete panels, including paint are 18 oz. each. The expected production weight is more like 12 oz. Here's why...

We're using a 1/32" balsa laminate in the skin. We're also installing a wing tube and socket, and two servo boxes with hatches in each wing. The normal laminate would be .75 oz cloth on the outside, followed by several layers of 2 oz. cloth on the inside. We're waiting on the .75 oz. cloth, some lightweight primer and the 1/32" balsa, but feeling some time pressure to get a prototype flying, I used 1/16" balsa instead, some relatively cheap primer (heavy), and a "2/6" layup, instead. ( 2 oz. cloth on the outside, balsa, then 6 oz. cloth on the inside...heavy) Then add in the extra epoxy/Cabosil used, because some of my internal parts aren't quite right yet, and there you have the extra weight.

That's ok. I figure if the prototype flies well, we know the production model will be that much better. Test-part fabrication has shown us that the 12 oz. weight is achievable. Of course, if someone wants to pay for a custom carbon or Kevlar version, we can do quite a bit better.

Magne

Mike,
Thanks for the information. I think it is likely that you can reduce the weight quite considerably.
For your reference, in Composite ARF's manual for the Impact (F3A pattern) they say that they are using 2 oz glass / 2mm foam/2 oz glass, and they have virtually no internal structure other than a spar and supports for the wing tube socket.
I have not made composite wings yet, but I made a fuselage for a 2x2 meter electric pattern model, I used 2 x 49 gram/m2 (1.45 oz) glass outside / 1/16" balsa / 1 x 49 g/m2 glass inside, no internal ribs. Plenty strong enough. Of course, your loads will be different, I dont do 200 mph.
By the way, if I was to use different thicknesses of glass, I would have used the thicker on the outside, to give some "ding" protection.

Have a nice week-end.
Magne

Mike James

Hi Magne,

Thanks for the Composite-ARF info. (which I've read, in their downloadable PDF manuals)

We're looking at modifying the spar structure, to accommodate something like you mentioned. The jet-like sweep of the wings makes it a little trickier, but not impossible. This set was way overbuilt, with the heavier glass, internal ribs, and balsa skin. You can't twist or bend them at all. I agree that we can knock this down quite a bit before production, and we will. Better to start too strong, and work down, than the opposite.

I've done many balsa-sheeted foam wings in the past, and that has been my only vacuum bagging experience with wings. So, the most exciting and encouraging thingh to me was simply that my first ever set of totally molded wings came out flyable. And, the Kevlar skin hinges are really great. What a clean and strong system that is... Really nice.

I'll post updates here when we have the next set out of the molds... Should be greatly improved.
Take care.

NdFrSpeed

My Feedback: (1)

Question about skin hinges,,so to be able to use skin hinges on a all composite plane it has to be kind of built into the molds to make them work,,or you can take any all composite plane and make the skin hinge method,,


Thanks
Bob

Mike James

Bob,

Skin hinges are built into the layup, in the molds. It would be difficult, at best, to try and do it to a plane that's already made. Here's my article on how they were done... http://homepage.mac.com/mikejames/rc...sandparts.html ( Scroll down the page a bit. )

NdFrSpeed

My Feedback: (1)

Thanks Mike thats kind of what i though,,it had to layed up that way,,


Bob

Mike James

Ok...

After filling and sanding the fuselage seam, which I broke when pulling the first fuselage, Ive gotten the retracts and gear doors working. Tomorrow, a little fix on the main gear struts, so the wheels are vertical, (I over-bent the axle part a little) and then on to the gear door closing mechanism. (first photo) I'll be using a simple mechanical method, rather than extra actuators.

I've also built the servo mounts for the wings (on the hatches) and installed them, and installed the control horns. (2nd photo We need a bit more 1/32" balsa to construct the actual flying tailerons and vertical fins, which should be here in a day or two, and that will complete the prototype parts.

As this week goes on, I'll show you the gear door mechanisms, engine/muffler/tank installation, and other details. We'll be painting the prototype, then should be flight testing in about 2 weeks. More and larger photos are at http://www.nextcraft.com/j47_sportjet11.html

PS> For those of you who've looked at the internal wing structure... These wings are way overbuilt. I did that in the interest of time, so we could get into flight testing. (better overbuilt than underbuilt) But on production molded wings, we'll be going to a more Composite-Arf style structure, using the sandwich skin and almost no internal parts. Adding the 1/32" balsa in the layup has yielded much stronger wings that I predicted, and all those ribs are just not required. You can't bend or twist these wings, without applying enough force to actually break them. (I'm surprised and happy about that.)

jetflyer

My Feedback: (5)

Still looking real good Mike. Question though. Once you get your proto-type finished and tested. From start to finish, how much time will it take to turn out 1 model?

Completed the second half of the mold on my fuel tank. I will crack it open tomorrow after work.

JR Gautreaux

Mike James

Congrats on the fuel tank, JR. Nice work.

Production issues... We've just had this discussion in the last few days, created a couple of production timelines, etc.. with these results.

Working from the point of view of one person doing the labor and using only one set of molds:

There will be two major kit options. A "Deluxe" kit (like the prototype...completely molded) would take a single person about 10 days to fabricate, due to the mandatory wait times for different stages in the vacuum bagging and epoxy curing process. If we provide a "builders kit", which would be a fiberglass fuselage, canopy, hatches, internal parts, and foam wings and tail surfaces that the builder would sheet, (like a Pattern plane kit) then one person could fabricate 2 of those per week. (again, using only one set of molds)

So, depending on the level of commitment we can get from prospective customers on initial orders, we will determine if we can make some more molds, buy materials in larger quantitiies, hire additional labor, and all the other things that make the business practical. We're approaching that "pivot point" now. If customers will commit, so will we, but we cannot do it alone. We can produce more kits if there are more orders, same as any other new company.

To all modelers watching this thread... If you're interested in this kit, let us know, so we can figure these things out. Email me personally, so this thread doesn't become "commercial", before we've even started. We've agreed with RCU that once we're officially "in business", we will have to abide by the different posting rules that apply to manufacturers.