F86_SABRE

Joe... when you loft the wings do you actually decide on how many wing ribs you wish to have and then the spacing is made automatically or vice-versa?

Reuben

ProfLooney

naw i try and decide how many ribs I need to make the wing loft smoothly then loft the wing then slice it into however many ribs works out for framing. when lofting you want to be minimalistic as the less ribs you have the more smooth the flow and less chance for errors


right now I am still having some small probs

ProfLooney

Well been having nightmares again but I think I got a way around. I know the center section is correct as it is just a straight line across the fuse. I also know the outer panel is correct because it is also a straight line. the only problem seems to lie in the transition between the two i.e. the bend and shape change from guppy belly to symmetrical airfoils.

So the easiest way is to add more rib shapes to help hold everything together. Thus I lofted the two places I know works and will just add a bunch more ribs so when I do the full loft properly I dont get any bows in the wing like was pointed out earlier.

ProfLooney

I adjusted the front view to match what it should be for the center rib section and looks lot better now and matches the rest of the drawings

abufletcher

What you have here looks perfect. And the idea of breaking the wing lofting down into smaller sections sounds like a good approach.

ProfLooney

thanks Abu, but refresh the page because I updated the pic with the adjusted front view. the problem with breaking it down is I can't get the curved loft part to blend correctly mainly because of the trailing edge curves. Thus I will have to add several more ribs so I can loft in one piece to compensate for that so it is just a temporary measure to use to make the proper wrib shapes

ProfLooney

Well I took the outer panel and added several sketches for extruding planes to give me a ton of extra ribs which will force the lots in that panel to stay the way it is now when I loft the intermediate section

ProfLooney

Well I got all my good ribs made. Now after a short break I will come back and try to figure out the transition layout

ProfLooney

Ok kiddies as of now my loft looks good but I wont be happy camper until I start slicing it and checking to see if there are any distortions in the ribs which ill do tomorrow since my mind is trash right now

jaka

Hi!
Nice work!
But...The negative stabb incidence must wrong. When I first saw it on the plans I asked myself Why on earth have all that negative incidence?
I did not make sence to me.
So I had a quick look at the Confederate airforce He 111 (spanish built). As You can see if you look closely in the film (just after the sidemounted gun is shown) the He 111 looks to have no negative incidence at all in the stabilizer. The leading edge of the stab is in line with the centerline of the fuselage...Makes more sence to me.
http://www.youtube.com/watch?v=XFcsz...eature=related

abufletcher

Sure looks straight down the middle line in the video.

ProfLooney

Sorry Guys Ihave to disagree. with all the books and pics i have the stab is definately at a negative incidence. You can clearly see it in the rear view takeoff shot but even more so where the plane is settin tail low in the last picture and is horizontal to slightly neg. so when the plane gets flying into level plane the stab will be negative for sure.

ProfLooney

ProfLooney

Also from this color drawing Look at the camo the camo line is not straight along the fuse it goes from high on fuse to low in the nose and the stab follows this line yes it is earlier model but the tail never changed on it between the two models. so Iam happy with my choice.

Remember the center wing section has that big guppy belly and is also at a negative incidence. they would need the stab to have negative to lift the nose to get the proper airflow over the wing

jaka

Hi!
Have a look at pictures of the the He 111 (spanish version) and you can see that the stabilizer/elebvator is sitting in line with the pointed end of the fuselage and that the stab leading edge is not pointing down as in the Russian plans.

http://www.richard-seaman.com/Aircra...111/index.html

ProfLooney

sorry guys I don't buy it I have tons of books and pics and even my german book on the plane clearly shows negative incidence so that's the way I am building it. But thanks for double checking me and keeping me on my toes I appreciate all debates cause I can easily get so engrossed I miss something.  the angled views from some shows etc unless it is a head on view of the stab a lot of that is optical illusion

ProfLooney

Ok further along in my german book Ifound the answer which solves all the issues it is a 4.5 degree negative incidence

Nieuport nut

My Feedback: (10)

I agree. I think the problem with looking at photos is that rarely do you get a picture taken from exactly a side view. Then there are the problems with parallax. Also,the difficulty of estimating the relative incidences between a symmetrically airfoiled stab and a much thicker semi-symmetric wing with the varying incidence angles from root to tip.

Yep, I'd go with the contemporary references.

Have a look here too, (courtesy of Matz):

http://www.luftfahrt-archiv-hafner.de/

Martin

ProfLooney

Donkeyshine   Martin   

jaka

Hi!
Why not contact Confederate Airforce! and ask them send some photos of their He 111?

ProfLooney

I could BUT I have to have verifiable proof on paper for those that may want to use one for competition so it is easiest just to use the documentation I have and all my documentation from the 28 books I have all show a negative Dihedral so I will go with that especially the german book on the HE 111 which shows a dimensional angle. I figure the germans are best to know what angle their planes tail was as they prob have access to the plans or other documentation.

But overall it all boils down to being able to have the documentation for competitors and this way no matter what 3 views they use from any of the books I am using they all show negative incidence.

abufletcher

Joe, you've convinced me! Negative it is!

Now, of course, it's a whole separate question as to whether you want it like that on your model. Wing and stab incidence and engine thrust, these are all important model design issues (about which I know nothing). Some model designers may argue that you just can't do it the same way as on the originals. I don't know. For large scale WWI my gut feeling is that you CAN pretty much follow the original. But I just don't know anything about WWII, let along multi-engine WWII.

How are the Mosher plans in this regard?

ProfLooney

I started Lofting the Gondola tonight

ProfLooney

Abu Vance set his root negative and stab at 0 Now I had talked to him long time ago abt his airfoils and he said he didnt use the originals on this plane. I dunno why but he said he used a couple that were close.

on my WWII I have always used the original airfoils unless I couldnt find them and have all flown great. the teeny planes like 60 inch ws and below dont seem to fly very well with the scale ones probably because they are so light weight and most ppl fly them like crotch rickets. but when you get in the 80 inch or larger range they tend to fly just fine.

ProfLooney

besides the most the neg incidence is going to do is make it so the plane wants to rise (always a good thing) and setting in a little down elevator will solve that issue