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Old Feb 15, 2002, 03:24 PM
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San Francisco, CA
Joined Jan 2002
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Doing a Guillows FW-190 Conversion and...

Last night I framed 1/2 of the fuse after drilling what seemed like an endless number of lightning holes in the ribs. Well I looked at the "bones of the hawk" thread and the herr 30" conversion thread and noticed something very interesting: the ribs on these 2 models are barely thicker than the wide fuse stringers! On my Guillows kit the ribs are 2 times the thickness of the stringers. I think I will go home tonight and slice out the centers of my ribs and smile as I put the fuse on the scale and realized I have savd all that extra weight! Then, when it comes time to fly, I just hope I've got the skill to lay the bird down nice and soft...

Mars
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Old Feb 16, 2002, 12:07 AM
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Keremeos, BC, Canada
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Save WHAT weight???

If you have a really sensitive scale, I suggest you save all the bits you cut out of the structure and, at the end of construction, weigh them. The results are not as spectacular as you may imagine!

My mentor Walt showed me the difference, and then proceeded to show me that one extra coat of finish did away with that saving. One must look at THE WHOLE CONSTRUCTION PROCESS to see where the weight builds up. If you build the lower half to withstand belly landings or other such stresses, then the top should be built using light balsa to compensate. More often than not, someone wants to install retracts or flaps or 3a batteries or... and the weight saving takes a beating.

Look at the whole model!!!
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Old Feb 16, 2002, 12:08 AM
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Costa Mesa, CA
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Hi,

I'm doing the same conversion right now as well. I didn't bother with lightening the balsa though.

I have the fuse, tail feathers and wings done but not assembled and it weighs about 2.5oz.

I figure the weight for the whole plane will be 7.4oz or so.

Did you add the dihedral to the wings like it was mentioned in the instructions? I did and it looks kinda funny...

I'll post some picks after I get a bit more done.

Regards,
Rooster
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Old Feb 17, 2002, 07:45 PM
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United States, MI, Brighton
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What is plan for motor, batt, servos, etc?

I am interested in small warbirds as well. What is the rest of the plan?

JT
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Old Feb 18, 2002, 12:20 AM
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Costa Mesa, CA
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I'm going to start with an 8 cell 300mah NiMh battery and a 280 motor. Either DD with a 6x4 prop or geared 3:1 with a 9x6.

I would prefer to use the geared drive, but i'm not sure how much clearance I will have for the prop. Also, the gearbox / prop adapter, etc. will add extra weight.

I hope to have some pics up this week.

Regards,
Rooster
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Old Feb 18, 2002, 07:49 PM
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United States, MI, Brighton
Joined Feb 2002
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Seems like

The 280 would be overkill. how about LI cells? What servos, etc. Sorry but this stuff is what I want to do bad. So many free flight planes like this crashed (when I was younger) and I now have chance to do it right with some control.

Oh well - keep us posted - PLEASE!
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Old Feb 18, 2002, 07:53 PM
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United States, MI, Brighton
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And.........

I have the Sterling 25" FW-190. I think I can scan all this in, size it to something a little bigger - say 30"+ and have some ribs, etc. laser cut and build a fleet until I get it right. I think the foam wings may have some merit for this. I know there is other plans out there in the 1/12 scale but they all seem to be balsa skinned and I think this would add to much weight for an indoor fighter???

Just saw one of those Kavan Sopwith pups (30" span ~18oz) and it really zipped on a geared 280.
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Old Feb 19, 2002, 09:44 AM
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San Francisco, CA
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Details of my Guillows FW190(I Might be Crazy...)

I am trying to get my FW190 to come in between 5 & 6 oz.!
Here are the details:

HY-50B motor w/ 7.25" prop (5:1 Gear ratio)=0.75oz.
2 Cell Quallcom Li-Ion Battery=1.8oz.
R4P GWS Receiver=0.17oz.
2 GWS Pico Servos w/o lower case(elev. & Ail.)=0.3oz.
Pixie 7P ESC=0.1oz.

So, with these components I have between 1.88 and 2.88oz. for the airframe.

Right now I have everything framed except 1/2 of the wing and it weighs 1oz. I plan on covering with tissue. I might be crazy but I thought this would be fun to try!!

If my overall weight is 6oz. my calculation says my wing loading will be 8.6oz./sf. So, this plane should fly pretty fast.

If my HY50B does not have enough power I may try a 3-cell Qualcom pack which would increase my weight by 0.9oz. but almost double my thrust.

I do not plan on adding the extra dihedral to my model as I am making my ship an Elevator/Aileron ship as was shown in RC Microflight's article on the Micro Mustang.

As soon as I have the plane framed up I will try and take some pictures to post here.

Mars
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Old Feb 20, 2002, 12:27 AM
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Costa Mesa, CA
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Mine is going to be a tad heavier...

The plan right now is:

280 motor
3.5:1 MP Jet gearbox
8cell 300mah Nimh
2 Cirrus 10-BB sub-micro servos
GWS 4RP receiver
Dymond 5A ESC (3g)
APC 9x7.5E prop

Right now everything weighs 8.4 oz. I also plan on covering with the tissue supplied, using water based polyeurethane (sp?) and 50/50 water/alcohol to shrink the tissue.

I just finished the rudder tonight and it turned out pretty good for my first time.

I would be interested in motor alternatives, however, as nothing is set in stone yet. According to MotoCalc, if the plane comes in at 9.4oz., it will fly fairly fast with a run time of about 7min WOT.

Mars -- I'm planning on rudder / elevator...I would like to see pics of the ailerons to see how you did it.

Also, do you plan on painting the tissue? If so, what kind of paint are you going to use, how many coats, etc.
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Old Feb 20, 2002, 09:53 AM
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San Francisco, CA
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A Bit More Info

I will try to post some pictures when I get access to a digital cam. There is one here at work that I can borrow from time to time.

I have been experimenting with the idea of dying the tissue with a non water proof ink I got at an art store. It gives a somewhat translucent finish that really screams "stick and tissue aircraft". I kind of like it but am thinking that an opaque finish might look better... Last night I tried to paint the ink on the plastic parts in the kit and they held the color pretty well after I used 600 sandpaper on them. If I use the inks I will paint the top a burnt sienna color and the bottom a light blue.

Rooster--Are you going to brush on your paint or do you have an airbrush? I think an opaque paint job will cerainly look more scale than a translucent one. My brother has an airbrush I could borrow to paint Poly paint on my model, but the last time I tried to use it I gave up!! I might try and paint an opaque finish on with a brush after I do an experiment or two to find out how good I can make it look.

Last night I received my HY50B from Cloud 9(very fast service!!!) and am now a little worried that my plane, if it comes in around 6 oz., will be underpowered. I really want this plane to have at least scale-like flying characteristics and have enough power to do loops and rolls. The only flying plane I have right now is a light stick and it is fun but I am ready for a little more speed and POWER!

For my first flight I may try an 8 cell 120 NiMh pack that weighs 1oz. instead of the 1.8oz. Li-Ion pack. this will give me +/-8V and save almost an oz. of weight. Of course I will only get very limited flight times.

Mars
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Old Feb 26, 2002, 09:55 AM
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Pictures and a question

Here is what I have finished so far. That is the HY-50B in the nose and here's my question.

I found a spread sheet showing 4x thrust values for this motor at different voltages. At 7V(2 li-ion cells) the number is +/-6.8oz. At 11V(3 Li-Ion cells) the number is 12. 8oz. So, at 2 cells my rtf weight is 90% of the rated pull (6/6.8) and at 3 cells my weight is at 55% of rated pull (7/12.8). Will I get much better performance out of 3 cells? At 2 cells my wing moading will be 9oz/sf and with 3 cells it will be at 10.5oz/sf.


Any help in sorting this out will be much appreciated.

Mars
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Old Feb 26, 2002, 10:15 AM
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Better picts

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Old Feb 26, 2002, 10:19 AM
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Aileron Link

Here is a picture of the linkage I built for the ailerons on my FW-190 from Guillows. THe yellow tube is the outside of a du-bro cable pull system. Inside of this I put 0.020 wire. THe horn on the servo end of this wire is simply 2 pices of 1/64" ply notched and glued, one on either side, to the wire.

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Old Feb 26, 2002, 10:20 AM
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Old Feb 26, 2002, 11:20 AM
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Cincinnati, OH USA
Joined Oct 2000
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Re: Save WHAT weight???

Originally posted by Terry Lyttle
If you have a really sensitive scale, I suggest you save all the bits you cut out of the structure and, at the end of construction, weigh them. The results are not as spectacular as you may imagine!

I agree with Terry on this one. Let's assume we're boring lightening holes in 6 to 8 pound density balsa sheet (typical hobby shop stuff). Let's say the parts are large enough that we can bore 1" diameter holes and that it's 1/16" sheet stock.

By my calculations, it'll take 11.2 of these 1" holes to save 1 gram. It'll take 315 of them to save 1 ounce.

And the news gets worse. Given the grain structure of balsa, boring holes weakens the part out of all proportion to the weight saved. In most cases, when all is said and done, you'd be ahead to make the part out of thinner sheet, rather than boring holes in the part.

Jim
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