TU 104 34" span QX 30mm EDF units - RC Groups
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Sep 27, 2017, 10:37 PM
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AntiArf's Avatar
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TU 104 34" span QX 30mm EDF units


Still trying to figure out what possessed me to start this subject, other than being seemingly unmodeled. Found a decent 3-view, drawn accurately where the views also match. No former cross sections, although the cocpit former seems to be accurately drawn on the front view. The remaining formers are close to circular, determined from the top and side views. The wing ribs are notched, with stringer locations penciled in on the plan, but tough to see in the photo. Somewhat comparable is a converted Cox Airlifter that will ROG with less than powerful EDF50 3-blade fans with 4100kv Feigao motors. Seems these QX fans can achieve similar thrust, if not better. With the QX fans, 34" span is about the minimum size needed to build reasonably scale nacelles, give or take a few mm.

Still at the less than exiting phase for a while, cutting out parts. Cut the basic wing kit, and just finished cutting the fuselage side keels. May as well finish the vertical fuselage perimeter keel and fuse formers next, getting more of the parts out of the way.
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Sep 28, 2017, 12:30 AM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by AntiArf
Still trying to figure out what possessed me to start this subject, other than being seemingly unmodeled. Found a decent 3-view, drawn accurately where the views also match. No former cross sections, although the cocpit former seems to be accurately drawn on the front view. The remaining formers are close to circular, determined from the top and side views. The wing ribs are notched, with stringer locations penciled in on the plan, but tough to see in the photo. Somewhat comparable is a converted Cox Airlifter that will ROG with less than powerful EDF50 3-blade fans with 4100kv Feigao motors. Seems these QX fans can achieve similar thrust, if not better. With the QX fans, 34" span is about the minimum size needed to build reasonably scale nacelles, give or take a few mm.

Still at the less than exiting phase for a while, cutting out parts. Cut the basic wing kit, and just finished cutting the fuselage side keels. May as well finish the vertical fuselage perimeter keel and fuse formers next, getting more of the parts out of the way.
Awesome project idea my Friend!
Latest blog entry: My RC 737 Assembly line!
Sep 28, 2017, 02:08 AM
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WAGliderGuy's Avatar
Cool subject! Subscribed
Sep 28, 2017, 03:30 AM
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Rudi's Avatar
Quote:
Originally Posted by WAGliderGuy
Cool subject! Subscribed
Agreed
Sep 28, 2017, 08:27 AM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Very nice, that was one i noticed that wasn't modeled.
Sep 28, 2017, 08:57 AM
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Dirty Dee's Avatar
Subscribed.

Not sure if you've seen this 4-view, but it might be a good reference too (no cross sections though)
https://www.the-blueprints.com/bluep...lev-tu-104.png

here is something I noticed from Wikipedia:
Quote:
The design request was filled by the Tupolev OKB, which based their new airliner on its Tu-16 'Badger' strategic bomber. The wings, engines, and tail surfaces of the Tu-16 were retained with the airliner, but the new design adopted a wider, pressurised fuselage designed to accommodate 50 passengers.
So you might be able to use some cross sections from the TU-16 to help get the shape of the 104
Last edited by Dirty Dee; Sep 28, 2017 at 03:07 PM.
Sep 28, 2017, 02:13 PM
Registered User
Should be an interesting build. Never really studied a 3 view of one previously. Lotsa wing span vs fuse length. Seems almost as Military.
Interesting LG pods.. also the lack of fuse windows in proximity to the engines is curious.
Wonder what the interior arrangements were ?
Sep 28, 2017, 11:11 PM
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AntiArf's Avatar
Thanks for the comments. Airliners being nearly circular cut a nice break on the need for sections. Most are almost perfectly circular with the widest point basically at center height, drawn with a protractor, blending the two radii. The cocpit rear section is the oddball, where the widest point is a hair below the fuselage centerline and the top curvature has a bit smaller radius than the bottom. I've seen some 3-views where they don't get these perspectives correct, while the two drawings I've come across seem to have gotten it right. Unless something is fairly oblong, I've often ended up having to do as much padding/sculpting using sections from drawings, versus just lofting them by hand. The former dimensions are all determined from the fuselage perimeters on the drawing also. Makes using printed sections only a shaping guide, as you have to use the actual measured overall dimensions from the drawing. Even the former thickness itself has to be taken into account. As the fuselage curves toward the ends, I consistently use the smallest of the two dimensions measured on either side of the formers, when measuring overall former dimensions. Just the thickness of the former creates a wide variation, depending on which side of the former the measurement is taken from (1-2mm is a lot). Ideally the stringers fully insert flush into the notches, on the side of the former facing toward the tapering fuselage end, and lift up a hair out of the notch on the other side of the former, due to the fuselage curvature.

Got the vertical perimeter keel finished as well as the side keels, so onto cutting formers.

Span: good thing. I like airliners with generous wings. The interiors are a real throwback, more DC3ish. The windows are another interesting dilemma. I imagine they did have some scatter shielding around the engines. Thought about making clear windows, as on the 33" Comet. They're a real chore however, and then the stringers have to be located out of the way, being another less than ideal situation. Probably will just go painted windows, although with clear cocpit glass. Speaking of scatter shielding, I found some lipstick tubes that look promising for reinforcing the QX fan outrunner bells, which have been known to unravel on several people. The idea would be to cut rings from the tube and slip them over the bells. The plastic is fairly thin also, which is desirable, as I'm not wanting to increase the bell diameter any more than necessary.
Sep 29, 2017, 11:57 AM
Registered User
Scatter shielding for the passengers did come to mind but the DH comet with 4 engines in similar config had normal windows
Seems as there are skylights? on the TU fuse .. mere curiosity is all.
Lipstick tubes read as clever. I had imagined metal lipstick tubes (bygone age ?) though.
Plastic ? not so promising.
Likely Ali tape is tougher, certainly easy enough to apply.
It's also possible the 2 reported motors that burst...did so in odd circumstance.
Sep 29, 2017, 10:26 PM
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AntiArf's Avatar
The motor bells probably wouldn't need much reinforcement. I'm guessing the ones that let go may have had less than adequate seam joining (spot weld or whatever) or balance issues. The only issue I've had with tape is that the glue can slip with heat. The adhesive on aluminum tape is long lasting and heat resistant, but could slip under heat.

I thought the skylights were interesting, as they add to cost and are a reliability issue. Interesting that they were added on a early Soviet era airliner.

Cut templates for the nose formers and main tube former. The former at the front of the cocpit glass line almost always requires a bit of padding, to get a clean shape when blending with the window frame keels. Airliners are about as easy as they come though, being mostly round. The tail former sections have only slightly different radii. At the large tube section, the height is slightly larger than the width. To make a consistent former shape, I draw the two radii on paper with a compass, but only sketch a smooth blend on one quadrant of the circle. The part is then folded vertically and horizontally, cutting the other quadrants using the first one as a scissors guide, also using the compass drawn arcs as a guide to make sure that the folds were placed on dead center. Works better than trying to blend all four quadrants by hand sketching, and then expecting them to all be the same.

The perimeter and side keels were also made, joining fairly straight sections so as to not waste wood. Balsa is cheap, when a full sheet isn't wasted to cut a single piece keel, and stronger as the grain can be kept straight along the keel. The sections form up quickly, trimming them close to the profile in the area, and then shaping a bit with a block, for a perfect match to the curve. A few angled joints glued together with CA joins the keel sections together.
Oct 03, 2017, 08:54 PM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by AntiArf
The motor bells probably wouldn't need much reinforcement. I'm guessing the ones that let go may have had less than adequate seam joining (spot weld or whatever) or balance issues. The only issue I've had with tape is that the glue can slip with heat. The adhesive on aluminum tape is long lasting and heat resistant, but could slip under heat.

I thought the skylights were interesting, as they add to cost and are a reliability issue. Interesting that they were added on a early Soviet era airliner.

Cut templates for the nose formers and main tube former. The former at the front of the cocpit glass line almost always requires a bit of padding, to get a clean shape when blending with the window frame keels. Airliners are about as easy as they come though, being mostly round. The tail former sections have only slightly different radii. At the large tube section, the height is slightly larger than the width. To make a consistent former shape, I draw the two radii on paper with a compass, but only sketch a smooth blend on one quadrant of the circle. The part is then folded vertically and horizontally, cutting the other quadrants using the first one as a scissors guide, also using the compass drawn arcs as a guide to make sure that the folds were placed on dead center. Works better than trying to blend all four quadrants by hand sketching, and then expecting them to all be the same.

The perimeter and side keels were also made, joining fairly straight sections so as to not waste wood. Balsa is cheap, when a full sheet isn't wasted to cut a single piece keel, and stronger as the grain can be kept straight along the keel. The sections form up quickly, trimming them close to the profile in the area, and then shaping a bit with a block, for a perfect match to the curve. A few angled joints glued together with CA joins the keel sections together.
Ahh yes construction begins! this is a great idea for a build, I've never seen a RC TU-104 outside the Russia before. . . Or in Russia for that matter.
Latest blog entry: My RC 737 Assembly line!
Oct 03, 2017, 10:33 PM
A Day @ a Time - Matt. 6:25-34
ruff1's Avatar
Bring it on!
Oct 04, 2017, 11:32 PM
Registered User
AntiArf's Avatar
Figured I'd start on the fuselage, since the wing will take up the table, and then I'll still have something else to work on. Standard full former, built in mid-air construction. Came out quite straight, especially considering the length. 17.9 grams, which can reduced a bit by shaving keels/formers, once a few stringers are added, which add a bit of strength/stiffness.
Oct 05, 2017, 01:01 AM
Up-Out-&-Gone
demondriver's Avatar
Quote:
Originally Posted by AntiArf
Figured I'd start on the fuselage, since the wing will take up the table, and then I'll still have something else to work on. Standard full former, built in mid-air construction. Came out quite straight, especially considering the length. 17.9 grams, which can reduced a bit by shaving keels/formers, once a few stringers are added, which add a bit of strength/stiffness.
Love the balsa Fuselage bulkhead & stringer method, tried & true building technique.
Latest blog entry: My RC 737 Assembly line!
Oct 05, 2017, 11:26 AM
Registered User
jumo004's Avatar
I really like the the smooth lines and shape of this plane ....


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