Logo
Builders' Plan Gallery  |  Hip Pocket Web Site  |  Contact Forum Admin (Account/Technical Issues)  |  Contact Global Moderator
September 25, 2020, 08:13:48 PM *
Welcome, Guest. Please login or register.
Did you miss your activation email?

Login with email, password and session length
 
Home Help Search Login Register
Pages: 1 [2] 3 4 5 6   Go Down
Print
Author Topic: Farman F190  (Read 6034 times)
0 Members and 1 Guest are viewing this topic.
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #25 on: January 05, 2013, 07:10:45 PM »

I'll probably go with 25% bigger then. Thanks chaps.

The other tempting tweak I am probably going to succumb to is... (Bill, look away now please) sneaking in just a bit of dihedral. I've yet to risk a dihedral-less model and apart from anything else I want the option to fly outdoors from time to time as well.
Logged
Ian Melville
Silver Member
****

Kudos: 3
Offline Offline

United Kingdom United Kingdom

Posts: 168




Ignore
« Reply #26 on: January 06, 2013, 01:29:57 AM »

The Lacy M10 seem to go well enough without dihedral, indoors at least. If you squint the Farman isn't that far off a Lacy, though you may have to give the band it's marching orders Smiley
Logged
SP250
Gold Member
*****

Kudos: 12
Offline Offline

United Kingdom United Kingdom

Posts: 494



Ignore
« Reply #27 on: January 06, 2013, 11:56:35 AM »

Pete

You could also try (assuming you haven't thought of it yet) using a wing section with a lower pitching moment and making the tailplane an inverted lifting section.  That way the small tail area has less to do in stabilising the model.  Combined with a 20% or less CG and lots of up elevator, you may even get away with the scale tail area then use Bill's idea of changing to a larger one if it doesn't work.

Regards John
Logged
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #28 on: January 06, 2013, 12:54:51 PM »

John makes a good point there. Reducing the airfoil pitching moment relieves the tail of some down load. And if you are building separate control surfaces then a little up elevator has the same effect as inverted camber.

I'm sure you've found this already but looking at the wing as seen on the Salmson engined version here:

http://aero.passion1.perso.sfr.fr/Page172.html

Shows the wing section as being near enough flat bottomed and pretty thin. This is good for a reduced pitching moment (and generally for small models) Dunno if you've started the wing yet but I'd be looking at something like this:

http://airfoiltools.com/airfoil/details?airfoil=ag03-il

Quite thin for structural stiffness though...
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #29 on: January 06, 2013, 03:40:36 PM »

Thanks. I'm sure this is all sound advice but I'm going to keep it simple and just enlarge the tailplane by 25% as suggested, and add a bit of dihedral. The model will not be very competitive static-wise in any case, as the example I'm making is quite poorly documented. It will still be appealing to me though and so long as it flies that's my main objective met.
I haven't started the wing yet. I plan to use split ribs as I enjoyed them on the Polikarpov and they were not as fiddly as I feared.
All advice still welcome of course! Smiley
(Jon, I had previously found that cache of Salmson-engined photos. Thanks though- very handy to have the link on here)
« Last Edit: January 06, 2013, 04:01:06 PM by Pete Fardell » Logged
Phugoid
Guest

« Reply #30 on: January 06, 2013, 06:46:39 PM »

Be careful chaps, you are talking about quite a lot about theory here, and no one wants to see you being humiliated for such "thought experiments"..... Grin

Personally, i'm with you pete, just make a guesstimate and try it - keep it simple.  In my day to day design job i rely on what my old design lecturer at Hatfield Poly used to say ........"if it looks right - it probably is".  His only caveat to that was ".......as long as no one dies if it fails"

So I suppose it depends on whether or not you decide to trim your model with or without the band aboard.. Grin Cheesy

Andrew
Logged
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #31 on: January 07, 2013, 11:31:08 AM »

Sorry Pete, Andrew. Waffle over. 25% tail enlargement and a scale airfoil look about perfect to me. I probably ought to shuffle off and build something now....  Embarrassed

Actually this thread and Dave P's model have got me fancying my own F192  Grin
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #32 on: January 07, 2013, 04:51:23 PM »

Jon, please don't hold back on the numbers stuff. It's obviously part of the hobby's enjoyment for you and though I admit I don't usually understand a lot of it, you do a great job of making the theoretical side of it  sound more exciting and interesting!
Logged
Phugoid
Guest

« Reply #33 on: January 07, 2013, 05:16:51 PM »

I agree, my bad Jon  :'(

I never fully understood it when I had to study it, that's why I specialised in engines and undercarriages.  The later always made me unpopular in design projects, I mean all that unwanted weight that you have to lug into the air Grin

Andrew
Logged
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #34 on: January 07, 2013, 05:35:14 PM »

Haha sorry, I wasn't in a huff  Grin I genuinely do need to address the ratio of research:building  Cool  I made a supreme effort this evening and glued in a whole two wing spars  Cheesy


Pete, do you have a reasonable 3-view for the F190 salted away somewhere or are we stuck with whats onth' interweb?  Sad
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #35 on: January 07, 2013, 06:35:07 PM »

Jon, I'm about to PM you about my Farman 3-view (actually a very nice 5 view)
Logged
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #36 on: January 07, 2013, 07:09:45 PM »

Cheers Pete.
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #37 on: January 27, 2013, 11:50:47 AM »

With my Messerschmitt finished I'm back to this now. My plan was to finish the 109 in January, leaving Feb to do this Farman and March to complete the C02 Polikarpov, thus giving me a chance entering both it and the Farman at the Indoor Nats. Well for the time being I'm slightly ahead of schedule. Don't suppose that will last though!

Here we go with the wing then. 26" is quite large I know, but with its broad chord it seems even bigger to me, and the thought of turning within the Nottingham walls is already beginning to haunt me. I'm building over the enlaged 3-view as usual. Split ribs again as there are rather a lot so I'll hopefully save some weight (and I really enjoyed this method on the PO2). The wing will have two spars in more or less scale positions and a narrower third spar on the aileron line. I'm making the ailerons hinged this time in a bid to avoid the old trim tabs!
Attached files Thumbnail(s):
Re: Farman F190
Logged
Graham Banham
Gold Member
*****

Kudos: 24
Offline Offline

United Kingdom United Kingdom

Posts: 710




Ignore
« Reply #38 on: January 29, 2013, 03:13:49 AM »

Looks great Pete!

At 26" it'll have no problems circling at Nottingham, but you will need the dihedral you've already mentioned.

If it were me (and this is in no way a criticism, just my own personal preference), i'd have built the wing as a one piece structure and sat it on the fus rather than use separate panels. For me it makes it structurally easier to make a robust wing with consistent dihedral and incidence on both sides. Also allows the struts to be non-functional and therefore lighter. 

Looking forward to more progress on this and the Po-2!

Graham
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #39 on: January 29, 2013, 05:21:57 AM »

Thanks Graham,
Glad you said that about dihedral. I really wanted to put some on and now you've justified it even more! Grin
Good point about a one piece wing. There are a couple of reasons why I've done it this way though. For one thing I'm kind of using my Guillows F24 as a structural basis. This has separate wings and the general layout and struttage is quite similar to the Farman. Also, photos of Farman 190s (like the attached one) show that the trailing edge drops slightly below the fuselage topline so I thought my way might be more scale (not that that will do me much good when the wings fall off!).
You're right though- it's rather a big wing to be supported by struts. I suppose there's no reason though why I can't still join the wings by running the spars THROUGH the fuselage, just underneath the fuse top covering? Maybe I could slot the fuselage (which is sheeted at that part) and just drop the wing in.
Attached files Thumbnail(s):
Re: Farman F190
Logged
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #40 on: January 29, 2013, 05:49:37 AM »

...I suppose there's no reason though why I can't still join the wings by running the spars THROUGH the fuselage, just underneath the fuse top covering? Maybe I could slot the fuselage (which is sheeted at that part) and just drop the wing in.

I was looking at that bit too Pete, but mine was going to be less scale  Roll Eyes. Slotting the spars through would make it all stiffer and stronger. Just a thought: firstly, if you do it that way, you could flip the fuselage over on top of the wing centre section on the building board to position the root wing ribs, then you'll get a nice snug fit (this does depend on when/where you add the dihedral, you might want to angle the root ribs). Secondly if you don't cut the spar slots full depth at first, then you can align the wing/dihedral by sanding them a hairsbreadth deeper one at a time until the dihedral is equal.


Jon
Logged
dputt7
Titanium Member
*******

Kudos: 97
Offline Offline

Australia Australia

Posts: 2,168




Ignore
« Reply #41 on: January 29, 2013, 07:40:55 AM »

Hi Pete
Love those scale rib spacings. I built my wing in one piece and attached it to the top of the fuse then built a raised part over the center section so the wing was below the top of the fuse. I think the one piece wing does allow for lighter strut arrangements and is certainly lighter overall. When it comes to attaching the oleos to the struts its much easier when the struts not trying to hold on the wings. But I'm sure you have this all worked out in your head.
following with interest Dave
Logged
Graham Banham
Gold Member
*****

Kudos: 24
Offline Offline

United Kingdom United Kingdom

Posts: 710




Ignore
« Reply #42 on: January 29, 2013, 08:06:20 AM »

Pete,

I do high wingers similarly to Dave; a one piece wing but with the fuselage sides built so that the mating surface to the wing underside is set at the correct incidence angle. This often means the sides are 'notched' so that when fitted, the wing T/E sits below the aft fuselage upper line. It's then simple to cut long triangular pieces of balsa to continue the line of the upper fus sides over the top of the wing to the point where the fus and wing section blend together, and then add a couple of cross members between these on top of the wing to support the covering.

However, in this case notching the fus sides to enable the spars to be continuous would be a very good idea. I've found with indoor the flight up-loads on the wings aren't normally the problem: it's the impact (and even a 'greaser' landing has an element of this) on landing and the resultant download on the wings and struts that cause the breakages.

 
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #43 on: February 05, 2013, 07:19:45 PM »

Well 44 split ribs and a fair bit of other wood later and I'm setting the dihedral. I settled on a Jenga block under each tip to start with (1 Jb), but then upped it to a Humbrol tin (1 Ht). In imperial measures this is about 3/4" , once you allow for the height of the little jig I made to rest the middle on.
Lots of shaping and sanding to do, and then I plan to drop the whole wing into the fuselage. I shall probably join the rearmost spar together too, but not the L or T edges. The main spars need to slot down into the fuselage exactly where I've cross braced the top, so I think I'll just remove those two braces and let the wing spars do their job instead.
Attached files Thumbnail(s):
Re: Farman F190
Logged
Monz
Platinum Member
******

Kudos: 152
Offline Offline

United Kingdom United Kingdom

Posts: 1,231



Ignore
« Reply #44 on: February 05, 2013, 09:17:26 PM »

That's a gorgeous looking wing Pete.
Logged
Phugoid
Guest

« Reply #45 on: February 07, 2013, 01:55:38 PM »

Very nice Pete, that looks really cool.

I like your new units of measure too.  We once had a fitter at work called Peter Mouat that used to use loctite sealant like it was going out of fashion - he was notorious for it.  So the unit of measure of loctite became a Mouat, or since a Mouat was a large quantity, we used the unit milliMouats in specifications Grin Cheesy...

So how many milliJb's wide are your wing ribs?

Cheers,

Andrew
Logged
Pete Fardell
Palladium Member
********

Kudos: 151
Online Online

United Kingdom United Kingdom

Posts: 5,838


Topic starter


Ignore
« Reply #46 on: February 15, 2013, 06:10:39 PM »

I don't know, but I like the milliMouat!  Grin

More progress. Not exactly Monique-ing along but getting towards the covering stage. Parts shown here weigh about 17g. Don't know if that's good or not really. I enlarged the tailplane by 125% as suggested and also made another fin and rudder, this time just 115% bigger. The scale one I'd already done just looked too small.
Next worry is the undercarriage. If I make it scale length then the biggest prop I can get on there will be 7", and even that will be pushing it. Seven inches seems rather small 26" span model. On the other hand, any lengthening of the basic u/c might be rather obvious as it will have a knock on effect to the other wheel struts, which are quite numerous.  Huh Advice welcome!  Smiley
(I've already fixed the front main wheel strut wire, but it's not yet cut to length.)
Attached files Thumbnail(s):
Re: Farman F190
Re: Farman F190
Logged
Monz
Platinum Member
******

Kudos: 152
Offline Offline

United Kingdom United Kingdom

Posts: 1,231



Ignore
« Reply #47 on: February 15, 2013, 06:15:32 PM »

Ahem...  Cheesy

Looks great Pete and I think, for the size, the weight is pretty good.

Logged
Rich Moore
Platinum Member
******

Kudos: 45
Offline Offline

United Kingdom United Kingdom

Posts: 1,495




Ignore
« Reply #48 on: February 15, 2013, 07:13:06 PM »

An extra 1/4" length on the u/c would gain you 1/2" on the diameter of the prop. Would that notice? Maybe ever so slightly overscale wheels would eek out an ickle bit more...I wouldn't want to push it far.

Looking really nice...

Logged

It wasn't me
Yak 52
Titanium Member
*******

Kudos: 70
Offline Offline

United Kingdom United Kingdom

Posts: 2,562


Jon Whitmore



Ignore
« Reply #49 on: February 15, 2013, 07:16:14 PM »

Lookin' super Pete! I've been drawing my version of the 192 and I've really fallen for this little plane. By the way I've ended up doing separate wings in the same way as you, it just looks righter somehow. And simpler for the windscreen area.

Any thoughts on the engine yet? Mine is dead easy since it's a psuedo-dimer. Been fiddling with different drawn versions though.

The prop size might not be an issue if you can keep it light. Mine will have a 4" for ROGs (bigger for outside) but if it's light and with all that wing area you should get your qualifying time? Is there much of a penalty for UC lengthening?


Jon
Attached files Thumbnail(s):
Re: Farman F190
Logged
Pages: 1 [2] 3 4 5 6   Go Up
Print
Jump to:  

Powered by MySQL Powered by PHP Powered by SMF 1.1.21 | SMF © 2015, Simple Machines Valid XHTML 1.0! Valid CSS!