Hi Rate1

You could by a 1/2" (or 12mm or so) End Mill as used by model engineers and remove some material from the Cowling Bulkhead without cutting all the way through. You would ned to clamp the part to your drill press to stop it flying off into the ether tho'

Cheers

...we are talking about part CW1 or? CW1 is 3mm thick...

Hi Rate1...I thought mine was 1/4" thick...I'll go check tomorrow but you could be correct. If 1/8" (3mm) you could always incorporate lightning holes and and fill them with balsa...you are going to have to fuel proof it anyways.

Cheers

I am more concerned with what to do about the turtle deck. I certainly don't want the ABS plastic thing, nor on the hatch, but prefer a balsa or foam structure instead.

I suppose I could use balsa stringers and then sheet the turtle deck and hatch with either balsa sheets or 1/64" ply. Clueless for the moment. Wich method will you use for these and why?

I am still a fan of making a plug out of the stock abs thing, making a mold from it, and then making composite turtle decks. Just my 2 cents.

Hey, after that you could sell turtledecks to other builders of this kit.

Zope pope,

That is a good idea and well worth to investigate on how to as I have never fiber glassed before but very much would like to learn.

Na, no one would buy anything of my craft... []

Stringers are in place and soon this fuz itself will be ready.

Don't be so hard on yourself. I am sure many will be offering to buy your extra when its done 2 lbs under everyone elses weight. :P

Superworm,

I am thinking about put a lightening hole in the middle of the landing gear plate. This is 1/4" thick ply and is in turn supported by the sides of the engine box What do you think, how big hole in the centre of this plate in order not to risk its structural integrity? Considered the loads is straight up, through this plate and not bending....

Well I went ahead and did it anyway... [>:] Purhaps I was a bit careful on this one as it is a part that probably are going to take some beating...
Saved a wimpy 10% on the gear rail doubler with that hole . Landing gear plate approx 0,07 oz.

Superworm, do you plan to use the stock turtle deck or to construct an alternative one? If so how do you plan to go about it? Also, do you plan to use the stock ABS hatch or...?

Another topic about this kit. I personaly think that the Extra 300 is one of the most beutiful designed plane there is out there and this obviously because of its lines. One of these lines making up this beutiful aeroplane are the fuzelage side stringers wich in this kit is excluded. These side stringers are running in the middle of the fuz, along the lenght on the side of the fuz, from main wing to the tailplane. To put back what have been removed in this kit for a more scale apperance I plan to use a thin balsa stick or a possibly lite ply. See attached pic to see what I am refering to. Obviously this little stringer is going to make the covering harder to acomplish nicely, but in my mind well worth it and by chosing the right material and construction for it with a very little weight penalty.

Also, depending upon what weight I will complete this kit, it might with some luck be within 3D wingloading, I might then considering some what larger controlsurfaces. This to make an fairly old kit and traditional aerobat to a more modern and 3D friendly plane (not completely into a 3D plane wich it will not be with the limited modyfications I am making). However, for this I need foremost a bigger rudder than that out of stock. Also it is not just a matter of cut out a bigger rudder from the foam core as this is restricted by the fuz wood construction. The only way of getting a bigger and more modern size rudder on this plane is to extend it aft. To do this I might have to either replace the foam core with a balsa construction or cut out a replacement foam core that simply is bigger... When this is done I could easily match the rest of the controlsurfaces by just cutting them slightly bigger. The question is if it is worth all this extra work?

Anyone having any ideas on these isssues?

Hi Rate1

Your fuse is looking good so far...you will have overtaken me on build very soon.

. I think I mentioned earlier that I was going to use a 1/32 or 1/64 or proskin turtledeck. It is my intention to have this essentially as a non-loadbearing structute which will be removeable to access the servos, linkages, etc. It will be held on using small socket roundhead screws (I think I got them from "Great Planes") My plan is to create 3 formers at the front middle and back of the deck....the front is easy, iirc we have a former in the kit. The rear former can be developed from the plastic turtle deck and the middle former will be an interpolation of these two. The formers will be notched for stringers at the top and each side such that the side stringers rest on the top of the fuse box flush with the outer sides noting a slight allowance for the solartex covering. The skinning for the deck will overlap the sides (i/c solartex by about 1/4" and the screws will pass through this overlap into the sides and internal longerons. The screws will be pitched as per scale using Bob Banka's photo's of Patty's mount. I shall retain the back end of the plastic turtledeck in way of the fairings around the tail group (or may use that as a plug for a f/g equivalent...ABS can be a little brittle!). The ABS hatch will have to go also...construction as per turtledeck.


Can't argue with that...only the Hawker Hunter comes close!...Methinks you (used to have?) some of those in your neck of the woods.....anyone in the good olde US of A can see one at Grand Canyon Airport (a Swiss one!)

As the fullsize airplane is framed up with round tube, I intend to use round section hard balsa for all the bottom stringers (I shall use white painted dowel for the tubes that are visible within the Cockpit and note that I intend to glaze various parts of the underside as per full-size). In addition, the stringer that you mention, is definitely going on my Extra (imo it would look daft withoout it). My intention here is to again use round section hard balsa which has been sanded flat to a taper at the most aft point and almost round just fwd of the cockpit rear. If you look at your full-size picture, you will see a diagonal line on the fuse which sort of extends below the line of the cockpit canopy at its aftmost point. On the fullsize, aft of this line is fabric (hence the solartex) but forward is either a metallic or cfrp cladding (don't know which for sure, all the full size I have seen have been painted!). Again my intention is to use 1/64 ply (or proskin) to replicate this panel so the fuse will only be solartexed from the rear to just under this cladding. The cladding will extend fwd to the engine cowling's aft edge.

I think my Rudder will turn out slightly larger than stock since I need to make it a little fatter and hence longer to wash out the additional thickess (maybe 1/8"). I'll explain later but it is associated with my requirements for the Fin/Rudder shrouds or covings (methinks the proper term) and the fact that I am designing the tails to be removable ...seems all the weight you are saving on your Extra is going on mine!. I'm not sure if I agree with your 3D specification tho....there are already planes out there which are far removed from scale in order to be anywhere near good at 3Ding. In any case, the way Patty throws her fullscale version around, there is plenty of 3D capability as designed.

Later

Cheers

Wow...great responce Superworm,

Firstly, yes we do have the Hawker Hunter here. Actually is lives in the same terminal area from where I operate the Cessna Caravan in Skydiving operations and yes mate it is a pice of beauty.

Yes you did meantioned some about the turtle deck previously on this thread. My misstake.
Do you think using 1/64" 3 ply is lighter than balsa sheet, or is it just slightly heavier but are offering other benefits compered to that of balsa sheet?
I was thinking to give a try to make either a foam turtle deck and cover with balsa, or as you suggested go for 3 formers and then a skin ontop of that made from either balsa or 1/64" ply. Another way alltogether is to mold a light weight cloth fiberglass turtle deck. Wich construction to chose I dont know but it will most likely be the same for the hatch as chosen for the turtle deck. Saving the aft part of the turtle deck for the fairings is a good idea to save one self from loads of extra work.

Worth restating is that my goals is not to make this plane a 3D plane but to make the best classic aerobat I can. However if the wingload would be low enough there will be an option to have some 3D out of this frame as well. Needless to say this is not too realistic though as this would require a wingload of about 24 oz/sq.ft wich translate to a 10 lbs plane. In all honesty I will be thrilled if I manage to keep this plane at 11 lbs.

Lastly a little present from me to your exciting scale project, a picture showing glassed floor of the 300S.

Regards,

Christian

ok guys build away and enjoy it!!! i'm at a standstill for a bit. i had a thread started here in kit building to the story behind all this but it seems the moderators felt it needed to be in "the clubhouse" so it was moved and only took me a couple hours to find it again!! LOL

anyway...here's the link

[link=http://www.rcuniverse.com/forum/m_4761426/anchors_4761426/mpage_1/key_/anchor/tm.htm#4761426]my thread[/link]

i'll probably be a couple months behind you guys now!!! LOL

Hi Rate1
Methinks if you use balsa sheet, you are going to glass it (0.6 oz.sq.yd) and paint it or cover it with film in which case balsa would be fine. I would prefer the 1/64 ply since I will be less likely to poke my fingers through it. I will, however, research the thinnest proskin first. Can you get hold of 1/64 ply ? you could weigh a sample on your scales to compare.

Since the whole turtledeck is effectively single curvature (conicalish) I don't think there is need to mould it from glass..just go for the formers (or foam) and use the ply or proskin or glassed balsa sheet.

Thanks for the piccy (now I do like that colour scheme)....unfortunately I have to stick with Patty's 1997 scheme 'cos I have all the decals...and a model Patty...and a large modicum of allegience since she remains one of my heroines.

anon

Actually I already have the 1/64" ply at home, a got them through misunderstanding while ordering the contest balsa... Obviously it would be nice to use the thin ply instead of go and get some more balsa sheets for a rebuild turtle deck.

I just got off the phone with my mate and we are up for sheeting the wings this weekend (all weekend but only during evening time) at his workplace workshop. Since this is planed to happen on fri evening after I have been flying skydivers, all this in another city, I need to prepare all needed items (wings, skins ect) for a fairly quick operation. For this I am planing to sheet both sides of all the wing in one go.
Some people that is sheeting with vaccum is not edge glue the balsa sheets at all, but are mearly tapeing them together as it all is going to be laminated anyway. I am thinking about using this method but are still undecisive on that one.
Also I need to insert the balsa into the foam cores for the horns before going to this workshop. As well as think about the size of all the control surfaces to be cut out, as I would like to use the fine band saw to cut them out while I am still there. Otherwise I will have to pay another visit for this and I dont know when I could come back for all the nice tools they have there...

By the way, this school/work shop is located at the very same airport as where the Hawker Hunter is living.

For this stunt I will attempt to go for the vaccum technique (as stated before) to get a strong structure that need a minimum of resin for weight saving purposes. If things would not work as hoping for there is loads of weights we could use to weight down the cores with.
Lets hope I will manage to get everything ready for this and that there will be no snags.

I will weight the difference btw 1/16" balsa sheet and the 1/64" ply.

Hi Rate1

Methinks I would joint the sheets first (using a strip of masking tape along the joint) using Aliphatic Resin glue (looks like PVA or Evostick ResinW only yellow)...not CyA. Any excess glue can then be wiped off with a dampened kitchen roll tissue sheet. This way you have control and there is less likelyhood of error if the sheets become separated in the vac bag. When dry, you can then sand the sheets flush and trim (slightly oversize) each panel noting which is the best side of each sheet so that goes on the outside.

Tape two sheets together with several short pieces of masking tape acroos the join to pull them together and then add a length of masking tape (pref. the Blue stuff from 3M) along the whole length. Then fold them along the join to expose the edges..then apply the glue sparingly along the joint...then fold flat again. Wipe off the excess, then add the next sheet(s) likewise. Lay on a flat surface (tape down) and cover with film backing sheet or clingfilm and weight down with a few of your old magazines. Leave overnight to dry. Remove the tapes and lightly sand off the surfaces flush. Trim to slightly oversize (maybe 1/4 to 1/2 inch) then its off to the vac. bag with the whole caboodle. Good luck.

Cheers

PS

Maybe take templates of the root and tip of the wing cores..If you upscrew, you can then maybe get new ones made locally...you may have a problem with the joiner tube holes though...got to be some skill in removing those from a core!

You do have a point with having balsa sheets glued to become a whole skin does leave less likelyhood on things that could go wrong when vaccum compered to just have sheets taped together to make up a skin. I guess making a skin before this process is my best bet then... Thank you for the heads up. Doing so I will use the method you just described as CA glue makes is very hard to sand the made sheet true, leaving hard and almost impossible ridges to sand flat on the skin resulting in a poor finish.

Lanier RC do sell induvidual parts to this kit wich is a comfort if worst would come to happen. This is a much easier way for me to solve a catastrophic incidents since I am lacking skills and tools.

Hi All,
Lots of great posts in this thread. My Extra is coming along, although I have been into other things this summer. Building season is close and I will get back to the project soon. At this point I have the main wings sheeted, ailerons cut out, leading and trailing edges installed shaped and sanded, and the ends capped. Also while doing the sheeting operations I jumped ahead and sheeted the tail feathers. I know Rate1 has been interested in some FG parts. I got a nice FG cowl and hatch from Stan's Fiber Tech. Good prices too! [link=http://www.stansfibertech.com/]http://www.stansfibertech.com/[/link]

There is a great AMA article on a scratch built Extra they did a few years ago. [link=http://www.modelaircraft.org/mag/hurley/hurleyindex.asp]http://www.modelaircraft.org/mag/hurley/hurleyindex.asp[/link]
I found part 2 on Sheeting foam wings to be the most helpful. Three things that I took away from that section was the best method for joining your 1/16 balsa sheet together to form the skin, filling in the stress plate bay with scrap foam, and capping the ends of the tube socket with 1/8-inch light ply.

The method they used to join the sheets is really slick. You tape the sheets together with blue painter’s tape on one side. Then flip it over and let it hang over the edge of the table and run a bead of thick CA in the seam, then just slide it flat on the table and wipe the excess. My only advice here is to let it setup (5-10 secs) and flip it over onto wax paper and remove the tape and scrap or lightly sand off any CA that got on the other side. If you let it fully harden than the tape will get stuck in a few spots and any lumps will be had to remove. This method is way better than just pinning the sheets down and dripping thin CA on the joints which will result in lots of hard CA on the back side that cannot be removed.

Filling in the stress plate bay gives the stress plate two surfaces to adhere to for more strength on the part that the wing tube is relying on to stay connected to the foam and the rest of the wing. Capping the tube socket will keep the wing tube from migrating into the foam if it ever got loose.

When I get a chance I will dig up some pics of the progress so far.

BTW- The AMA article goes into vacuum bagging which could be helpful for those who plan to go down that road.

Nauset good stuff.

Myself included the cowl and pants when I order this kit from Lanier. Yes Stans is good. I had him make the cowl on my muched lover GP Extra .60. He has Good quality and excellent service.
Bummer I just epoxied the wing tube sockets into place about half an hour ago... Otherwise that does sound like a good idea. Why I did not think about that myself beats me?

You could always make up a foam filler piece and then cut it down the middle and epoxy the upper and lower pieces into place around the tube.

Well if I have calculated this correctly (converting sq cm to sq ft and grams to oz) I have the numbers for 1/64" ply and the kit stock 1/16" balsa sheet weight.

The 1/64" ply has a weight of 4,3 oz/sq.ft.
While 1/16" balsa sheet (stock from this kit) 1,5 oz/sq.ft.
-------------------------------------------------------------
Conclusion: Balsa sheeting has a third of the weight of 1/64" ply. Approx 1 sq ft is needed to sheet the turtle deck and if using balsa there is 2 oz of weight saving compered to useing thin ply. I am going to use 1/16" balsa sheet for this job (as well as trying to get my little hands on some more contest grade for even more weight savings).

I would difinetly be interested in how you constuct the turle deck as I don't like the plastic at all. Do you think the 1/16 balsa will be to flimsy?

For sheeting foam wings, this is the Bible:

http://www.mackrc.net/patternwings2/index.htm

For your turtledeck, the lightest way to go is to sheet a foam core with 1/16" balsa. It is reasonably rugged and simple to keep straight.



Mark

mmattokx, good link.

Nauset, I had built up balsa sheeting on 3 lite ply formers on my GP .60 and it was alright meaning it was light weight and not too flimsy. However, I will have a crack at mmattokx suggestion by trying to shape a foam piece into a turtel deck and then sheet it with balsa. If unsuccesfull shaping then I will ditch the foam idea and go for simple formers.