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Apr 25, 2010, 08:41 PM
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Build Log

Boeing B-47E Stratojet @ 1:8.7669


This project design phase began in October 2009 and progressed rapidly from an initial 1/11.48 aka 1/12th to 1/10.2, 1/8.693
then after EDF dims forced a scale change we ended with 1/87669. To give you a feel for where it began here is the initial datum
workup. The B47 has a large degree of offset to tag a phrase...




And the initial dims as a result of the workup.


Project originated as an EvoJet 90 kero burner then it moved to Stu Maxwell's StuMax 110-52 until the Dynamax was powered by
Little Screamer's monster motor that eventually became the XPS-Dynamax large can motor to provide 1/2 to 2/3 throttle thrust
required for my most challenging maneuver....the landing approach.



In the end, we moved to TamJets conversion of the Dynamax after XPS's Jim Drew announced end of life for their large can motor.
Tam packages the Neu 1915 1Y 8mm shaft motor to Tommy's Dynamax fan plus he adds an aluminum spinner and glass tailcone.



Note the "0" anhedrial/dihedrial engineering note on the Boeing B-47 drawing to explain the optical illustion when viewing a tapered
wing on a high rake angle shoulder wing aircraft.

In several books printed as reference materials for the Boeing B-47 family of America's first swept wing jet bomber you will find the
photo and "someone's "creative revisionist description of what an image observer's first impression can result in creation of an error!
I refuse to cast doubt on the knowledge base of those arthors for the simple reason explained below.

At the time when some reference books and materials were printed as "fact", the real facts were often hidden behind the curtain the
USAF/Gov pulled across all technical data during and just before the period to be known as the "COLD WAR". After this edict, nothing
was available for artists, documentarians, authors of both fact and fiction.

It was only after the B-52 rolled out of Wichita, KS that B-47 technical facts began to come back into the light of day/night. Boeing
was told to "burn" all technical data on the B-47 and continue the cloak over the B-52. From that point forward retirees were the
chief source of Boeing B-47 photo and technical docs. T.O.'s were "taken home" along with all those bricks in the wheel barrows
of Boeing, Douglas, and Lockheed employees as they left their B-47 manufacturing and maintenance jobs when they shut down.

These T.O.s took three years to track down. Only after the physical research efforts of Richard Reynolds and Mike Wilson were
we all able to filter out technical mis-information and speculation when they viewed microfische which had not been reviewed in
67 years... ;^)

Before you get all giggles over the 1947 and 1956 Boeing drawings and photos...you know it could not be that easy, didn't you

Note: The Boeing B-47 Stratojet wing is NOT a Clark Y....

Airfoil is a BAC 145 reflex to overcome the B-47's lack of power and need for penetration through the less than effecient spool
up of takeoffs and long approanches.

Note: BAC 145 has an elongated "virtual flat bottom airfoil the latter 3/4 of its airfoil create Clark Y style high lift.

Joy and pain are the scratch builder/designer's companion... You learn to temper your excitement / disappointment. Something
perceived to be of value and you casually look it over.......and over..........set it aside and look it over again later.



The fueslage to wing incidence on the 1:1 is 2 deg 45 seconds plus fuselage rear rake of about 2.4 degrees makes the B-47 look like it has anhedrial droop. It is a documented fact the B-47 has "0" anhedral. My Boeing drawings state and restate this fact. There is an optical ilIusion observed in the head-on and rear-forward photo views which not account for rear rake and taper of wings thatmakes it appear as if it has anhedrial.

Ah, you say "why then are there outrigger gear on the plane?" Because when sitting on the ground the struts settle and when full, the
wing tanks cause the wing to sag, on the ground and in the air. More about the "in the air" later on - -- - - - - - - --
Note: The Boeing B-47 Stratojet wing is NOT a Clark Y....

Airfoil is a BAC 145 reflex to afford its lack of power and need for penetration through the less than effecient spool up of takeoffs
and long approanches.

Note: BAC 145 has an elongated "virtual flat bottom airfoil the latter 3/4 of its airfoil create Clark Y style high lift.

The root incidence on the 1:1 is 1.5 degrees plus a fuselage rear rake of about 2.4 degrees makes the B-47 look like it has anhedrial
droop.



It is a documented fact the B-47 has "0" anhedral. My Boeing drawings state and restate this fact. There is an optical ilIusion
observed in the head-on and rear-forward photo views which not account for rear rake and taper of wings thatmakes it appear as if it
has anhedrial.

Ah, you say "why then are there outrigger gear on the plane?" Because when sitting on the ground the struts settle and when full, the
wing tanks cause the wing to sag, on the ground and in the air. More about the "in the air" later on Here are the dangles according
to Boeing engineers and their assembly T.O.'s.


- -- - - - - -
Last edited by FliteMetal; Jun 01, 2019 at 04:50 PM.
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Apr 25, 2010, 08:57 PM
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B-47E-IV Stu'd 2D Maxx


Initially StuMax 110 EDF was incorporated into my workup in inboard nacelles.

For a complete blow by blow of the initial design phase you can view it over on WattFlyer within the EDF Jets section.

I'm bringing you up to where I am today so posts will be reflection of where the project is...still, I will post enough to permit you to understand why I did not continue at 11.48%. Everything had to be re-engineered from the inboard nacelle~up to arrive at the 10.2% I could live with. 11.48% equaled 121.216" w/s @ an FAI F4C AUW of 33# sans batteries.

Last edited by FliteMetal; Jul 20, 2013 at 12:12 PM.
Apr 25, 2010, 09:40 PM
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CG Confirmation From BAC (Boeing Air Corp)




This project is building two (2) Flite-Metal poster children and one (1) spares airframe we hope to never have to use... ;^) My partner in this crime is Sam Collins who shares my interest in the B-47E-IV. After a friend's Tu-95 had proven there were no real issues on this planform...I charged forward.

Early on, Sam ordered a set of the B-47E flight and service manuals (700+ pages). That and 6 softbound, 1 hardbound, 3 DVD airframe manuals, plus 540+ meg of data gathered online, 1-1/72nd unassembled plastic model, 3 line art drawings, and 1 XB-47D planset from the 50's formed our initial resource pool.

The BAC general layout with dims provided the 25% of MAC location I would challenge and confirm. This matched George Maiorana's Tu-95 CG location so that was more than enough to press on. The Tu-95 and the B-47 are virtually the same airframe. The Tu-95 is turbo prop which serves it best at lower speed.

You are probably wondering why was I so tentitive...well to be totally honest, the B-47 1:1 and the three models which have been built of it since 1956 all exhibit the same issues. Severe dutch roll, an airframe too slick, an ineffecient (for a model) low aspect ratio, aileron blanked by laminar flow wing, an inability to hold heading during approach, and a rather high approach and landing speed necessitated by the above an the bicycle landing gear.

After reading that...you might wonder why anyone would want to build a B-47E-IV... :^) You will note you don't see them around anywhere. As a matter of record 4 XB-47D's have been constructed and flown in competition. All three were recip powered with four bladed props (2 @ 54" w/s and 1 @ 80" w/s)

AMA plans service has Mike Potter's 54" w/s XB-47D. Three were never any plans for Joe Martin's 80" w/s XB-47D. He said he never took
the time to draw it up as a whole plane. Let it surfice for the time being...all is well in B-47E-IV land after beating on this all this time.

Last edited by FliteMetal; Jul 20, 2013 at 11:45 AM.
Apr 25, 2010, 09:40 PM
Registered User
Sweet!
The guy that taught me how to fly RC back in the day flew these out of Chenault.

Signed on.



Julian
Apr 25, 2010, 10:26 PM
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Meaning Out Inconsistancies


One would imagine with this many multiple-view drawings I would enjoy a lot of resources. Unfortunately, none of the multiple-view drawings were scale to each of their individual perspectives, nor to each other nor were they more than artist renderings.

I spent over a month meaning out errors using photographic documentation & rescaling perspectives in an attempt to arrive at a single set of drawings for the project. Thanks to a gentleman on Ebay, I found this...



That's from the June 1956 M.(Model) A.(Airplane) N.(News) issue focused on the B-47E as one of AirAge's "Planes Worth Modeling" series. As it were...this drawing was a compilation of drawings provided by Boeing and redrawn by AirAge's artist.

Unfortunately, you are looking at its original printed size. After auditing it with photographs, it is a 144th scale drawing of the B-47E and RB-47E (long nose). Enlarged, it served as a validator of other drawings. I followed up with the editor who confirmed the larger original was probably hanging on the artist's wall or perhaps in an heir's attic.

Rich was encouraging, as always. He owns an original B-47 drawing by the same artist and it hangs in his office... He too has a yen to yang his way to a flying B-47. In fact, when this is done he'll have it all in his possession.

At least I now had a resource for additional cross sections. I was focused on the inboard nacelle since it would eventually contain my EDF, outrigger retract, batteries, ESC, and an Eagle Tree Data Logger. I could button up the nacelle, the removable pylon blade the nacelle is attached to, and the pylon.

Last edited by FliteMetal; Apr 25, 2010 at 10:50 PM.
Apr 25, 2010, 10:38 PM
3d and EDF, some scale
MustangAce17's Avatar
I've thought about one of these too,wouldf u mind sending me a copy of the last planes worth modeling pic,it'd ber very handy,my friend scratched a solid model years ago working at the ballistics lab in Maryland
Apr 25, 2010, 11:14 PM
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Beauty In The Eye Of The Beholder....Not accuracy :)


Before you get all giggles over the 1956 drawing... Yeah you know it could not be that easy didn't you...

Joy and pain are the scratch builder/designer's companion... You learn to temper your excitement / disappointment. Something
perceived to be of value and you casually look it over.......and over..........set it aside and look it over again later.

The root incidence on the 1:1 is 2.6 degrees with a 2.4 degree anhedrial droop. I decided that presented more angle of attack than I
wanted to load up on during the landing approach so I dropped it back to 1.5 degree incidence plus the 2.4 degree anhedrial. Airfoil is
modified reflex BAC#...I finally calculated and printed it.

There is a leading edge wing fence or what serves as initial evidence a wing fence to manage the issue of right angle flow down the
wing. However on the B-47 the fence is little more than an extension of the pylon fairing.

The aspect ratio permits lift to be maintained at the root out to the inboard nacelle during landing approach courtesy of the reflex design
of the laminar flow airfoil.





It affords a stable non-eddying flow across the bottom of the wing so the Fowler flaps and flaperons work well. Below is the actual airfoil
at the fuselage side...note the reflex is confirmed...D spar is not attached to this image of the foil.



That's all for now... In the immortal words of the California Governor... "I'll be back"...

Last edited by FliteMetal; Mar 20, 2012 at 10:35 AM.
Apr 26, 2010, 01:05 AM
Scale Modeler
Concordefan's Avatar
Hey Ed,

Great to you your thread here in this new section now, i have moved my Concorde thread here also, now we'll keep an eye on each others progress.....Construction will start very soon on my model, soon as i get my 3D drawings, i will get them printed and then start on the fuselage while wing drawings will be worked on.


Sam
Apr 26, 2010, 08:00 AM
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FliteMetal's Avatar
Thread OP

Not Yet... :)


Quote:
Originally Posted by MustangAce17
I've thought about one of these too,wouldf u mind sending me a copy of the last planes worth modeling pic,it'd ber very handy,my friend scratched a solid model years ago working at the ballistics lab in Maryland
Kyle,

The PWM drawing is too small to be of any value. Also the data on the page has been "
modelized
" by MAN's artist. Remember back in 1956 there were few who envisioned how to
model this at all, much less alter it to an XD.

While there are some valuable data points within the drawing, there is little to no reason for you to acquire
the drawing. You'll see why shortly... :^)

When doing a scratch build one should not forget the point of origin date for your data.

More often than not, if data comes from modeling magazines it was altered to compensate for issues not
described in the article or a planset created as a companion to an article. This is more critical the older
the article or planset.

I'm not going to beat this to death...but it is the most important issue when you design...
Power determines AUW (all up weight), flight behavior, landing transition speed, maneuver capability, flight
duration, life span of the model and ultimately the enjoyment
of the project when finished.

There is a planset available from AirAge (M.A.N.) today :^) One which can be built either as an XD or any
other version of the B-47. Its in their online plan catalog.

Propjet B-47D Description: A fine control-line scale model that could be modified for use with R/C.
W/S: 54 in.; L: 43 in.; engines (2) .15 Item Number: FSP05582 X05582 $14.95 USD.
You may purchase it by clicking here: https://secure.rcstore.com/pcd/eServ...aVN1YlRlcm09MA==

Someone might wonder why I would send you to spend $15 on a plan here in a scratch building thread. Its
a valuable resource, no different than if you'd searched for weeks to find cross sections...much less find
formers.



I hear the thoughts....that airfoil isn't scale. Multiple replies could address the fact models do not fly like
1:1 aircraft but this is not the time nor place :^) I want you to look upon everything as a resource from
which to work you way to where ever it is you are drawing your road map to...

Remember, each and everyone of you reading this has a completely different skill set and experience level.
Those, like me, with fewer skills, need the most documentation in order to accomplish whatever it is in our
mind's eye we see when we are finished construction.

Nothing, absolutely nothing is more valuable to you than documentation. If an itchy Xacto finger and a yen
for the smell of balsa dust is what you enjoy. its a cruel world out here in the world of scratch building.

Scratch building is 90% preparation and 10% construction aka assembly. This project has progressed so
rapidly it was shocking. When I began in October it was a vast wasteland of mis-information with minimum
indexing.

I caution you to not jump into a HORRIBLE mistake laden "build as you gather" information. All that is going
to accomplish is frustration. You might as well go pile up $20 bills and get comfy in their warmth and glow
while burning.

My thread is to permit you to replicate this build exactly...skipping ahead is going to be disappointing....I
guarantee it. For example would anyone care to comment on this illustration?


Last edited by FliteMetal; Apr 27, 2010 at 01:02 PM.
Apr 26, 2010, 02:21 PM
The 6 P principle works for me
elecfryer's Avatar

re: illustration


Jumping in with both feet here..... from what I have read (and believe!) the 47 had "take-off" gear, not landing gear meaning that you had to land at very close to stall speed and be VERY careful in regards to your angle of attack at touch down. Additionally a "light" 47 would just prior to touch down, encounter some degree of "float" as the lift generated by the wing would interact with the ground (ground effect) and perhaps extend the point of touch down and of course, you still needed to watch your angle of attack while floating down the runway!

Michael (if your not frying, your not tryin!)
Apr 26, 2010, 02:35 PM
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FliteMetal's Avatar
Thread OP

Landing Approach Speed & Angle


The B-47 and B-52 land level with virtually no flair. A bicycle landing gear configuration does not
permit flair. There are many many YouTube videos to witness this and the approach as well.

I am fortunate to have a full size airport to practice approachs and landing so back at Bomber it
will not be an issue on our 750' of runway. There are brakes for the rear gear.

An approach/heading chute is deployed during the approach to permit spooling and keep the nose
pointed where it belongs (into the wind). The drag chute is more of a cosmetic halo.

I anticipate the landing speed to be between 40 and 50 mph.
B-47 Stratojet takeoff, flyby and landing with drogue chute (0 min 41 sec)


http://www.youtube.com/watch?v=gFCx2...eature=related

B-47 in Profile (4 min 41 sec)

Last edited by FliteMetal; Apr 27, 2010 at 01:02 PM.
Apr 27, 2010, 08:07 AM
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Thread OP

Approach & Landing Issues Forced Rescaling Project


Continuing to bring you up to date rapidly...

The StuMax 110 was the intitial EDF consideration, then my choice after viewing an Australian 19# F9F fly in a very impressive/realistic manner on YouTube.

STUMAX 110-52 Ducted Fan ASM Panther F9F (3 min 27 sec)


Stu Maxwell had done his homework to attain what I required in moving 39#~41# AUW. Actual weight of the airframe for F4C is sans batteries...at 33# ;^)



My initial workup for EDF resulted in 1/11.483 scale...however after reconsidering the approach requirement and available thrust at specific RPM across the power bandwidth I worked up the pylon and nacelle at 1/10.2 to gain square inches to manage my approach and landing. What little was gained in weight was offset by much more control. The project is now at 1:8.693.


Last edited by FliteMetal; Sep 27, 2012 at 02:01 PM.
Apr 27, 2010, 08:21 AM
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Thread OP

Extreme Minimum Dim Compensation Required


There were minor dim compensations required to fit it all within the nacelle and pylon configuration I chose.


After reworking nacelle I arrived at 1/10.2 scale and these dims:

Wingspan: 137.19"
Fuselage Length: 120.72"
Maximum Fuselage Width: 11.14"
Nacelle Width: 9.653"
Nacelle Tube Length: 19.742"
Nacelle Total Length: 24.21"
Wing Tank Length: 27.56"
Wing Tank Diameter: 5.37"
Vertical Fin: 21.5"
Horizonal Stab Width: 38.22"




A = 5.06" B = 9.667" C = 11.14" D = 11.14" E = 10.12" F = 6.58" G = 4.56"]

Now, note the above fuselage cross sections relate to positions on only one of four drawings. The position of "G" above is lower than it should be with respect to the datum line shown on original drawing. In order for cross sections to be used, you have to audit the entire drawing using photographic documentation to assure proper alignment.

You will see my workups utilize extended datum lines to permit alignment of cross sections, each with its own shape and position... ;^) Rescaling and meaning cross sections across the length of fuselage produces an accurate representation of the B-47's fuselage. However, we are not that far down the road folks...

We're still here at the nacelle. What, you thought we were through here?

Last edited by FliteMetal; Apr 27, 2010 at 09:42 AM.
Apr 27, 2010, 09:49 AM
Oh Yeah!
SteveC68's Avatar
While you are at the nacelle, might I make an observation? IF (big if) you are planning on a 100% scale intake and exhaust diameter have you checked the exhaust diameter and matched it with the Stumax FSA? Based on the drawings you have shown, the exhaust diameter is going to be too small on the order of 1.25". Doing a very rough measurement of your drawings the exhaust diameter is 2.75". That's less than 60% FSA. While it would make huge efflux it would make poor thrust and probably have crazy amps. An 85% FSA would be about 3.5" diameter and this plane isn't exactly a fighter so you would probably want something in the 90-95% FSA which would mean 3.6" to 3.7" diameter.
Apr 27, 2010, 10:32 AM
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Continuing To Bring You Up To Speed On This Project


Steve,

Interesting statement since I have yet to declare my dims for either the inboard or outboard nacelle. I am
continuing to bring everyone up to speed on this project... My last sentence should have led you to know I
was not through

..."We're still here at the nacelle. What, you thought we were through here?".

I continue bringing you up to speed on where this project is...today.

The inboard nacelle single EDF is bifurcated to a "pair" of exhaust outlets.

All drawings you view are virgin or composited drawings from multiple line art with minimum to no initial
editing. What you are seeing are images from WattFlyer thread with 200+ posts. I chose to create this short
handed ramp up to bring you up to speed without dragging you through the evolution of the project.

I am sharing just enough to permit you to experience the process as a true scratch build... not a plan built model.
Everything you see was worked up from what would power the B-47...period. All scratch building must evolve
from this to achieve a model which will fit specific protocols...in this case FAI F4C.

Last edited by FliteMetal; Dec 28, 2015 at 10:24 AM.


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