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Old Nov 05, 2013, 07:37 AM
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United States, SC, Florence
Joined Nov 2004
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inlet ducting

Gianni,
I saw in your post that you were going to make inlet ducting, so that should take care of any problems with the fans starving each other for air.. Wow , you really opened up the bottom there for access!! Are you going to separate the fan exhausts, or just tie them both into the bifurcated tailpipe??? With stock bifurcated piece having two 3 and a half inch exhausts is there any concern about the eflux being a bit low. You probably read in all the previous posts,
how I ended up making a plug for molding a new tailpiece for mine. Maybe with twin fans this will not be an issue, just asking??? Looking good , on what you have done!
Roger
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Old Nov 05, 2013, 05:19 PM
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Belgium, Walloon Region, Mons
Joined Jan 2012
348 Posts
Quote:
Originally Posted by corsair nut View Post
twins should work great, but a word of caution...when using open ducting, and fan lips, your going to want to seperate the fans as much as you can. when they are that close, your going to have issues with the fans stealing air from each other, and causing losses in thrust. if you cant move them apart, put a wall between them
this is exactly what i've planned , but thanks for the help
i've already begin to shape some foam in the making of separate inlet ducts
this will be not an easy job!!
between the first template who take a lot of place and the gear area, there's a lot of curve to do to get them smooth enough....
well , i'm going to take a shower now, i'm embedded in the foam

roger , thanks for the encouragement , looking forward to see your progresses
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Old Nov 07, 2013, 09:47 AM
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United States, SC, Florence
Joined Nov 2004
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over on the other bench

Thought I would share what is going on on the other side of the shop.
It is P-51 which I am kit bashing. these are cockpit shots of my carved balsa interior. I am working on a similar F-18 cockpit.
Roger
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Old Nov 07, 2013, 05:02 PM
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United States, NY, West Seneca
Joined Oct 2005
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Carved balsa.... Awesome
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Old Nov 11, 2013, 11:55 AM
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United States, SC, Florence
Joined Nov 2004
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F-18 cockpit tub

Messing around with some balsa again, working on tub for F-18 and ejection seat, canopy lift pump, etc. long way to go . Plus trying to get some deer hunting in. So work on the stabs is going slow, and for me it kind of fussy work trying to be sure the pivot block and rod assembly is true in the stab will post pics of fitting it all together before glueing it up.
Roger
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Old Nov 11, 2013, 01:12 PM
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United States, MO, St Charles
Joined Nov 2002
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Hi Roger,
that's a good looking tub you have there. What did you do for the instrument panel?

Dan Eaton
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Old Nov 11, 2013, 02:11 PM
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United States, SC, Florence
Joined Nov 2004
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instrument panel

well I went on line and found some photos of panel. the first one was black and white. then I found a color one. I cut out the screens on the black and white, then laid the black and white panel over the color screens and glued them. Had to play with sizes of the pics until I got close to the plastic Byron panel top (that whole one piece black part). Did some % measurent calcs. and cutout the Byron piece to the appropriate size. I cut and shaped a balsa panel and glued the pics on it. clear coated it with semigloss polyurethane clear. Not the best, but not too bad for a budget deal. I will glass the entire inside of my tub to strengthen it and fill the wood grain. It will not be full depth, so it will clear the nose gear mounts, just down to the seat top and may still get made shallower , depending on the size pilot figure I end up with. I saw a nice 1/8 , 3/4 tall jet pilot
in the RCU jet classifieds. I hope will fit if not, I will settle for raising the floor of the tub for bust that the same company makes. The tricky part and very non-scale is the area behind the seat, where I will have to just fake something to look about right. This whole thing with the canopy attached will be removable to access radio gear and retract tanks and etc. The fuse has the the entire area under that black part filled in and had to cut away what was needed to get recess for tub. I chose to make a brace to support the the back of the fuse behind the seat area so I could make a some what scale drop down to simulate
everything that you see when the real canopy is open.
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Old Nov 13, 2013, 09:13 PM
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pilot info came today

The 1/8 scale pilot I am going to get, is about a 1/2 inch too tall for my cockpit tub. So it appears some alterations to my seat and tub will be in order . And, I may have to shorten the pilot some as well to get the proportions right. So it will in effect be a waist high bust. And the side switch panels will go away.. I made a small mismeasurement on the stab block and pivot pin location in the block. Which would not allow the stab to come up to the fuselage side when inserted into the mechanism. So have another block fitted up and it fits properly. Have to make another block again then I can start gluing them up .
Roger
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Old Nov 28, 2013, 02:46 PM
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making progress

I have one horiz. stabs nearly ready for glassing. It has been a bit trying, getting the pivot alignment true in the wooden block. Totally messed up the first one, not even close. Trying to drill the hole without any kind of guide. I started over and as I cut the new blocks I used the table saw and cut a groove 1/8 deep
in the center of the long piece I would cut down for the block. I then clamped two pieces together in the vice and started with drill bits long enough to go clear from end to end. Progressively getting larger until I got the correct size. Then I put thin layer of aeropoxy in the groove of each piece, followed by a layer of kitchen plastic cling wrap across one piece, then a long piece of my carbonfiber
arrow shaft, and doubled the cling wrap back over the shaft. I put the aeropoxy into the groove of the other piece and clamped the whole thing in the vice to dry.
The cling wrap kept everything form sticking together and the hardened aeropoxy gave me a perfectly true and straight groove to install the stab linkage pivot into along with a piece of arrow shaft to go into the original pivot hole. I had to cut a groove into the stab for the rods that go thru the pivot transversely as they protrude from the wooden block. I taped the assy into the stab and test fit into the the bearing/servo mounts on the rear former in the plane. It aligned perfectly so I then took it apart and aeropoxyied the block and pivot pieces and clamped in the vice to dry.
I epoxied the finished block assy. into one of the stabs, along with the stock wooden spars, the new balsa trailing edge, and the laminated carbon fiber and balsa leading edge. Did the sanding and here is a picture of the stab mounted on the plane. Along with some pics of the pieces for the second one.
Also a couple of pics of one of the wings I have started with the servo boxes installed in the wings instead of all the linkages and ball cranks. You can see the carbon fiber arrow shaft I installed in the wing for the servo wires to run in and to act as a extra spare. Also have installed some threaded wooden blocks for installing wing bolts for additional security when mounting the removable wings.
I should have the pilot figure in a couple of days , then I can continue with cockpit.
Happy Thanksgiving everyone!!!!
Roger
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Old Nov 28, 2013, 03:56 PM
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United States, TX, Schertz
Joined Mar 2006
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Looking nice Rodger.

Ed
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Old Dec 09, 2013, 06:46 PM
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United States, SC, Florence
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over and over until I get it right

I am continually amazed at the workmanship I see most of you guys doing on the other threads. And more than a bit disappointed that I have no experience in molding and forming fiberglass parts. There has not been much progress here as most of what am doing, is going laterally or backwards then forward again.
I am once again reshaping my tailpiece plug to give me the full area of 5" ducting coming from the fan to the tailpiece. I was coming up about 3.5 square inches short going into the bifurcated piece. And I already had one layer of cloth on the plug. There is no reason to hurry of to do it "close enough". My budget will insure that this will take a while to complete. And when I post pics of completed parts I want them to be comparable to what I am seeing on here.
I am thinking of using a piece of sheetmetal heating pipe 5" for a plug to mold the tailpipe that goes from the fan to tailpiece. Anyone think that would not work out for forming my fiberglass tailpipe???
The good news is a got a great deal on a new in the box, unassembled Dynamax fan unit for only $75.
I am building the jig for the fuse now also to ensure that the wings get aligned correctly. and will be glassing the horizontal stabs this week as well.
I was told that when balancing them, to find the amount of ballast needed to balance them then only install 80% of that amount. Without the glass on the stabs it takes 2oz to balance them. Any comments please??!!!
Regards
Roger
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Last edited by jetjock50; Dec 09, 2013 at 06:50 PM. Reason: adding info
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Old Dec 09, 2013, 08:31 PM
A-4 nut!!
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Vancouver B.C.
Joined Apr 2002
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Balance them after you cover and paint them.
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Old Dec 09, 2013, 10:33 PM
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thanks Skyhawk

Yea, I got that, just kinda wondered why Olinco said and Art Arro said to take out 20 % of the ballast basically leaving them somewhat unbalanced???
Roger
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Old Dec 09, 2013, 11:37 PM
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Roger, is Art Arro still around?
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Old Dec 10, 2013, 09:02 AM
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Art Arro

I exchanged messages with him a couple of months ago when I was trying to find out about the pivots point on these stabs. That was over on rcu in the aerodynamics forum. However I pm'd him last week about this question and have not received a reply. I hope he is well!!!
I have some info here from Skymaster that simply says to measure back 3 and a half inches from the leading edge and drill a 1/2 inch hole and add 2.8 ozs of lead to balance there f-18 stabs. But there is no info as to how they arrived at that. And their F-18F stabs are shaped different. These stabs already have 1/4 jnch hole at 3 inches back which was for a dowel for mounting the Byron control linkage. I figured on just enlarging that to 1/2 and adding ballast.
I read thru the article linked in Ron101's f-18 twin thread by, I think his name is Olinco. Which is where I read to balance in at the pivot, and then subtract 20% of the the weight and install it near the leading edge. Looking for some insight as to why, since that leaves the stabs somewhat unbalanced. The article does state that, but gives no explanation as to why.
Maybe< Mine is not to wonder WHY????!!!!!
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