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CD ScaleDesigns Albatros CI build

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CD ScaleDesigns Albatros CI build

Old 11-06-2009, 08:02 PM
  #276  
abufletcher
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Default RE: CD ScaleDesigns Albatros CI build

ORIGINAL: Nieuport nut
Why is this being sheeted with 1/32'' ply? Surely 1/64 would be quite adequate - lighter and closer to scale, (2mm?)?
Yeah, at the moment it's really nice 0.8mm birch ply (1/32"). I think I'd be worried about the durability of 1/64 ply, which would however probably do the same structural job, and would save maybe 100g. And, course, that would be weight saved in the tail.

At the moment, I'm pondering the question of how to make sure I get a good "no glue" stained and varnished look both on the inside and outside of the ply. I've been VERY VERY careful so far with glue but I haven't figured out a way to glue on the doublers without making a mess. Options were discussed on the first page of this thread, including pre-staining with water-based stains (which doesn't look very good in my opinion). Maybe that would be a good first step to help reduce the need for touch-ups later over "white spots." I really want to use varnish/lacquer, but need to be a bit strategic about when this is done.

Two cosmetic issues that need to be address now are 1) some way of "hiding" former F4a (which holds the lower tier of servos) and 2) a nice hardwood dashboard to go over the face of former F4 (which is at the scale location for the dashboard).
Old 11-06-2009, 10:16 PM
  #277  
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Default RE: CD ScaleDesigns Albatros CI build

Model Masters Acryl water based enamel for the interior.
Get a nice tan or sand color that will compliment your exterior colors. It is OPAQUE, goes over anything with total consistency and looks perfectly fine when looking down into your cockpit. The stain is NOT worth the effort or problems. The Acryl will look better and totally eliminate the problems.
Old 11-06-2009, 10:49 PM
  #278  
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Default RE: CD ScaleDesigns Albatros CI build

But what about that "just waxed Pledge shine" to all my fine furniture?
Old 11-07-2009, 02:35 AM
  #279  
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Default RE: CD ScaleDesigns Albatros CI build

If of some help, I glued all the 1/64 ply panels with Stix-It; and all is still together...
Old 11-07-2009, 07:42 AM
  #280  
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Default RE: CD ScaleDesigns Albatros CI build

Hmmm... 1/64 ply...hmmm [sm=50_50.gif]
Old 11-07-2009, 08:54 AM
  #281  
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Default RE: CD ScaleDesigns Albatros CI build

If you hand me 1/32 and 1/64 separately, I cant tell the difference; together you can tell, but they are so close in reality.
Old 11-07-2009, 09:28 AM
  #282  
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Default RE: CD ScaleDesigns Albatros CI build

Really? 1/64 is a lot more flexible than 1/32.
Doc
Old 11-07-2009, 09:49 AM
  #283  
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Default RE: CD ScaleDesigns Albatros CI build

Good news! My engine was FINALLY returned! After four months lost in the limbo of international business. So I was able to build the new engine compartment and mount the engine (at least temporarily).

I build the mount step by step, making sure the angles were right at each step. The interlocking parts help reduce the possibility of errors but even so 1 or 2 degrees of movement is possible and that would be unacceptable. So here it is all trued up, epoxied to the frame, the the RC91cd sitting proudly in the bow of my "boat."
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Old 11-07-2009, 09:54 AM
  #284  
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Default RE: CD ScaleDesigns Albatros CI build

ORIGINAL: TFF
If you hand me 1/32 and 1/64 separately, I cant tell the difference; together you can tell, but they are so close in reality.
The 1/64 always feels brittle. []
Old 11-07-2009, 10:25 AM
  #285  
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Default RE: CD ScaleDesigns Albatros CI build

I am conscious of how obvious is what follows: “be afraid of every gram put behind the CG”.
In my C III, despite of over 250 grams of the dummy Mercedes; of an entirely of copper “shoehorn” exhaust for the certain not light Laser 90, to balance I was forced to put a lot of lead (550 grams!) in the nose.
Old 11-07-2009, 10:39 AM
  #286  
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Default RE: CD ScaleDesigns Albatros CI build


ORIGINAL: GianFrancesco

I am conscious of how obvious is what follows: “be afraid of every gram put behind the CG”.
In my C III, despite of over 250 grams of the dummy Mercedes; of an entirely of copper “shoehorn” exhaust for the certain not light Laser 90, to balance I was forced to put a lot of lead (550 grams!) in the nose.
I have this very same fear and I think I need to see what possible weight savings are possible at every step of the rear construction (and the tail construction). I'm planning to cut down the ply doubler (as most of it, honestly, isn't needed) and it's probably a good idea to use 1/64 ply at least for the rear part of the fuselage. I may also see whether there's any "fat" to be trimmed off the forward fuse now that it's all locked together.
Old 11-07-2009, 12:32 PM
  #287  
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Default RE: CD ScaleDesigns Albatros CI build

I have two sheets of ply the same size here next to me, one 1/32 and one in 1/64. TFF is right, even by just looking at them there is hardly any difference. Gian is a fortunatel person living in Spain with a dry hot climate throughout the whole year very unlike our friends from further up in the northern hemisphere that has to deal with humidity in the summer and moisture in the winter. Using 1/64 ply for the fuse would make my worry about buckling and /or warping under different enviromental conditions. I guess 1/64 behing the CoG is fine, but I still need to see a large shett of 1/64 that is not buckled even when it is just been delivered!
We've all been watching Allan's thread on his amazing Siemens Schuckert which has lots of scale detaisl and a heavy scale finish. Still Allan says he's happy with the 24oz per sq ft it came out at. Using that as a guide the CI would have a max weight of 18lbs and Allan would still be pleased. Please don't let us panic here and get into a frenzy where we're shaving of the very last ounce until what we have hardly resembles the proto model. Use the doubler as it is (and have a good look at the rear l/g struts and the bottom wing brass tube while you're at it - ever had a bumpy take off?) and maybe 1/64 ply for the fuse behind the CoG and you'll be fine.
Old 11-07-2009, 06:24 PM
  #288  
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Default RE: CD ScaleDesigns Albatros CI build

How many square inches does the CI have? 18 lbs. is 288 oz. divided by 24oz per sq ft equals 12 sq ft or 1728 sq in. My 1/4 scale Nieuport 28 has 1600 sq in. Something wrong with your figures Abu.
Doc
Old 11-07-2009, 06:45 PM
  #289  
GianFrancesco
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Default RE: CD ScaleDesigns Albatros CI build

Unfortunately (for the climate sense) I am not living in Spain but in Italy; Rimini is in the north part of the Adriatic sea; our climate is warm in summer but a lot humid; winter is not very cold but often we have to deal with the fog........
Old 11-07-2009, 07:11 PM
  #290  
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Default RE: CD ScaleDesigns Albatros CI build

Gian, what is the total weight for your CIII? I'm thinking that the CI should fall somewhere around 6-7 kilos. But to be honest, I'm not very good with such estimates.

As a rough calculation, based on some quick measurements of the wings, I'd put the wing area of my CI at about 1800 sq. in (top wing panel is about 42" x 12" and bottom is about 33" x 12"). A 15lbs model (about 7kg) would be 240 ounces so...let's see...um...

((Sounds of brain churning and clanking))

1800 sq. in. = 12.5 quare feet.
240 oz. divided by 12.5 = 19.2 oz./sq. ft. Seems to me that we should be aiming for around 20 oz./sq.ft on a model like this. But I'm certainly no expert.

http://www.airfieldmodels.com/inform...ng_loading.htm
Old 11-07-2009, 09:01 PM
  #291  
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Default RE: CD ScaleDesigns Albatros CI build

Back in the old days (when I began flying, 1968 or so) we used the formula that 16 oz per 100 sq in was trainer territory. Then every one began using sq ft, which is 23 oz per sq ft using the same numbers. 24 oz per sq ft is a very lightly loaded aircraft. Many large scale models exceed 45 oz per sq ft these days "but the larger a model is the heavier the wing loading it will tolerate. Something about reynolds numbers and the cube relationship. I'm a retired mechanic, not an aeronautical engineer, but I know from flying over these many years what seems to be acceptable. Abu a model the size of the one you're building would have a very acceptable wing loading if it approached 30 oz per ft. or even 32. I dont think weight is going to be an issue with the CI but the bottom line is and will always be that lighter models fly better. To worry about warping on a completed and fully framed model is needless, "but" if it's a concern that 1/64 may not be as "bulletproof" as 1/32 then use the 1/32 and dont agonize over the weight.
Doc
Old 11-07-2009, 09:14 PM
  #292  
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Default RE: CD ScaleDesigns Albatros CI build

Boy, yall are a tough crowd.
Old 11-07-2009, 10:49 PM
  #293  
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Default RE: CD ScaleDesigns Albatros CI build

OK. I'm convinced. I'll just go ahead with the build as planned. But I do think it's important to have these discussions at the early stages of a prototype build. I can more confidently go forward now.
Old 11-08-2009, 03:31 AM
  #294  
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Default RE: CD ScaleDesigns Albatros CI build

These are the readings of the C III shown in our European usual units of measurement

TWA =Total Wings Area ( without stabilizer area) dmq. 111,9

WTWA=“Working” Total Wings Area (without stabilizer area) = 80% of above (*) dmq. 89,5

Weight Kg. 5800

SW/TWA Ratio g./dmq 51,8
SW/WTWA Ratio g./dmq 64,8

(*) coefficient which takes into account the interaction between the two wings of a biplane



A lot more difficult for me is to convert the readings in oz., sq. feets, sq.inch. and so on


TWA =Total Wings Area ( without stabilizer area) sq.ft. 12,04

WTWA=“Working” Total Wings Area (without stabilizer area) = 80% of above sq.ft. 9,63

Weight oz. 204,5

SW/TWA Ratio oz./sq.ft. 16,98
SW/WTWA Ratio oz./sq.ft. 21,23
Old 11-08-2009, 05:02 AM
  #295  
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Default RE: CD ScaleDesigns Albatros CI build

Thank you very very much for that information! Yes, 5.8 kilos for a 1/6 scale CIII, is very impressive. So the 6-7 kilos total weight I proposed seems like a good ball-park figure. In my opinion, 8 kilos would start to be on the "heavy" side for such a early aircraft. I would very much be expecting to get a "trainer-like" wing loading, rather than something more appropriate for a fighter (or worse yet, WWII warbird).

The following suggests that 20oz/sg.f would be appropriate for sport models.

http://www.csd.net/~cgadd/eflight/calcs_wingload.htm
Old 11-08-2009, 08:52 AM
  #296  
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Default RE: CD ScaleDesigns Albatros CI build

Have a look at this site:

http://www.ef-uk.net/data/wcl.htm

This takes into account the better weight carrying capacity of larger wings.
Personally, at 1/6 scale I really like 16 oz./sq. ft. Much lighter is a challenge in any wind, much heavier is less forgiving. Remember too, that biplanes can handle less wingloading for a similar handling to a monoplane - 24 oz./sq.ft is great on a sport plane, less so on a scale bipe.

Maybe you should build another Nieuport and try to get the weight down. I have a 1/6 N.11 at 3.5 lb, (14 oz./sq/ft) and a 1/5 N.12 at 8.75lb. (17 oz./sq.ft), both of which take off easily - apply power and the tail is up and the rudder is effective before much swing can develop.

Just my 2 cents.

Martin
Old 11-08-2009, 09:30 AM
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Default RE: CD ScaleDesigns Albatros CI build

ORIGINAL: Nieuport nut
Remember too, that biplanes can handle less wingloading for a similar handling to a monoplane - 24 oz./sq.ft is great on a sport plane, less so on a scale bipe.
That's why Gianfrancisco's calculations only use 80% of the total wing area to calculate wing loading.

Maybe you should build another Nieuport and try to get the weight down. I have a 1/6 N.11 at 3.5 lb, (14 oz./sq/ft) and a 1/5 N.12 at 8.75lb. (17 oz./sq.ft), both of which take off easily - apply power and the tail is up and the rudder is effective before much swing can develop.
That's pretty impressive and good to hear. My now demised Legionnaire was around 3.5 kilos. Anyway, I don't think I'll be building another Nieuport anytime soon. Comically, considering the time I spend on it, I don't even like Nieuports that much. I just figured it would be an easy model to try scratch-building (which is what got be going on building in Japan).

Anyway, back to the CI. Did some testing of various oil-based varnishes today and the "rose" gives the most personally pleasing hue (on the left in the photo). But I might also try a custom mix of the Rose and the darker Mahogany (which by itself has an unpleasant purplish hue). My plan is that I'll mask off the surfaces that will later be glued and then give the rest a couple of foundation coats of the varnish. This won't completely eliminate the problem of "white spots" but will minimize it. Also the varnish can be put on thicker on the light glue to cover this up later.

Anyway, that's the plan. We'll see what happens. At this point, I just want to get on with it.

PS. One other small thing was to ad lock-nuts (is that the right word for those little dealies with spikes?) to the bottom of the engine mounting beams. Once this area in enclosed there'd be no way of getting at ordinary nuts.
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Old 11-08-2009, 10:53 AM
  #298  
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Default RE: CD ScaleDesigns Albatros CI build

Tee nuts or blind nuts, invaluable little devices, also threaded inserts work well where the work is only accessable from the top and the pull load isnt too great
Doc
Old 11-09-2009, 03:59 AM
  #299  
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Default RE: CD ScaleDesigns Albatros CI build

Blind nuts, yes, that's the terms I forget over and over. So, after taping off the "gluing surfaces" I put on a couple rough coats of varnish. Now when I glue on the side panels I'll only have to worry about glue spotting on those side panels and not the formers. Well at least that's something. The second coat of varnish didn't go on as nicely as the first coat since the thinner softened the prior layer a bit. After the sides are on, the inside will all get more coats of varnish so I have another change to even it all out. It doesn't have to look great right now. It just has to give the wood enough color to avoid the glue white spots.

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Old 11-09-2009, 09:19 AM
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Default RE: CD ScaleDesigns Albatros CI build

The ply doublers have been glued on with a strategic combination of Titebond, CA, and epoxy. I used Titebond on the varnished former sides, CA around the bottom to make a quick bond to set the location, and epoxy up front were it can't be seen and were the strength is really needed. I needed to add a small bit of triangle stock to the rear of the F1 former to have something to glue the doubler to.

Note: Before gluing on the panels I files the chambers/bevels onto the sides of former F2. I didn't do the bevel on F1 until after the double was in place and then I could just sand it down to the line of the side wall. Finally, I haven't epoxied in the front of the right hand side ply doubler because must of this will have to be cut away to accommodate the engine cylinder.
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