B-47 1/16th Scale, 6 EDF Model

[Capt. Midnight]

Hi B-47 Modelers!

Flight Metal's 1/10th-scale B-47 looks like it is going to be a fantastic model - much beyond my capabilities, for sure.

However, as an ex-Boeing employee, and former SAC (B-52 squadron) pilot, I thought there might be some interest in a slightly smaller version of this aircraft, and one with 6 fans, as in the Boeing aircraft. So, I'm going to post some information on the model I hope to build, but don't expect all the fine-grained detail that Flight Metal is posting.

I've managed to track down some data on the B-47 wing airfoil, and, subject to some further input from Boeing Archives, will use that for the wing; the horizontal and vertical stabilizer airfoils are unknown to me, but I'll use NACA 64A010 of suitable thickness to start.

Here's a photo of my horizontal stab./elevator layout; the (scale) span is 24.75 inches.

I'll try to add some further info depending on my progress.

Cheers,

Dave P.

[Flite-Metal]

Looking good Dave! What is the length and wingspan?

[Capt. Midnight]

Here's a few more details on my B-47 model:

W/S: 87 inches
Fuselage length: 80.34 inches

Sources:

Museum of Flight B-47E, s/n 51-7066 (photos and dimensional data)
Dimensioned 3-view drawing from Boeing Archives Office
1/72nd scale Hasegawa plastic model kit
"Boeing's B-47 Stratojet," by Alwyn T. Lloyd (2005; ISBN 1-58007-071-X)

[GGRN]

Capt Midnight, your project is close to mine in dimensions : 1/15th WS : 90,5" L : 78,7". The structure is all from 3 and 6 mm Depron (to be as light as possible) and the fuselage is already built. The airfoil is the good old Clark Y. 6 EDF and retracts. Which material and EDF system do you plan to use for the structure and propulsion ?
Philippe

[Capt. Midnight]

Hi Philippe!

I will be using my 'normal' balsa/basswood-stick and balsa sheet, with heat-shrink covering technique (same as on my 1/12th-scale model of the BAC TSR 2 - see attached photo).

I have never used Depron, but have taken contact with one of the local "experts" on the material (he has built almost exclusively with it, and his models fly very well). Depron is not readily available in my local area (Seattle/Bellevue, Washington), but it can be purchased in various thicknesses and quantities. As I get further along in the B-47, I may see if I can get some and give it a try.

My plan is to use 6 HET 6904 fans (from ICARE/ICARUS in Canada - apparently they are very close to the Wemotech Mini fan, but with slightly higher thrust, according to ICARE).

How is your model progressing, and what fan will you use?

Regards,

Dave Plummer

[GGRN]

Hi dave !
Depron is a lot cheaper than balsa here... So i'm like your friend, and almost build my models with it. I'm targeting a very light model (around 1,8 - 2 kg ready to fly), so 6 GWS EDF 50 with Feigao 5300 Kv (total thrust around 900 grams) should provide enough power. I like those Fans and built several models with them in the past (S3 Viking, Su 25 Frogfoot, FW TA 183, Airbus A 318, Airbus A 340 and Me 262) with very good results, even with brushed motors for some of them... So let's hope this Stratojet will not be an exception... Be back on the build next week-end !
Regards

Philippe

[Capt. Midnight]

Hi B47ers!

I've been plinking away on 'Section 41' (the horiz. and vertical stabilizers, elevators and rudder) for the 1/16th-scale version of the aircraft. Below is a photo of these units temporarily assembled - check fit. I'll post a few more of these assemblies after a bit more progress.

Cheers,

Dave P.

[Flite-Metal]

David,

I assume you ordered and are using the Model Airplane News AirAge Publishing featured
B-47D planset.



That plan vertical fin and horizontal stab design with carbon fiber vail should do very well.

You asked about station locations for specific shapes. I traditionally use station numbers as
a "zone" in which a shape fits. I suppose because you used technical drawings when you
worked at Boeing you tend to lean more to an explicit location on the drawing equating to a
mirrored location on your model.

I tend to weigh heavily on reminding anyone willing to pay attention to my foolishness that
artists are not engineers. Engineers typically net the worlds worst artistic work as it more
often than not is explicit and harsh.

Think in terms of artist drawings as warm and fuzzy. Yes, you have my permission to join the
now thousands of people considering me either OCD, stupid, or nuts.

I recently replied to your station inquiry within my 1/10.2 B-47E-IV thread. My reply said to
render the cross section background transparent with its lines (perimeter & datum) in black.
Next, align image with datum lines you established on your project control drawing. Next,
using directional control keys on your Golden Delicious move it left and right as if to "slide"
along your project control drawing....until it fits.

What is it about this that is any different than standing in FedEx Office with project control
drawing at 1:1 and introducing another cross section... its transparency lets you print the
drawing at 1:1 with the new cross section in place as part of your fuselage unit set.

Lots of people appear to think because they don't use CAD they can't scratch build. This is
clearly not true. I recommend the following tools be acquired to enable a computer to work
up any multiple view into a model.

People with Microsoft Operating Systems regardless of flavor:
Microsoft Image Composer... (1 program)

People with an Apple operating system regardless of flavor:
Any, if not all Adobe image editors falling into a group referenced as a suite intended for
editing images, photos, and text. Many of these products can function within either the
Windows OS or the Apple OS. Example: PhotoShop, Illustrator, Premier, etc.

You do not have to become an expert to use these tools...and tools they are. They are
no different than a hammer and various styles of nail, or screw driver and carious style
of screw.

Usually, what we as modelers need to achieve is to resize, and convert to a transparent
background in order to place image on top of another image to either add to or simply align
prior to "consideration" for addition to your project control drawing.

As I have probably over illustrated on my thread...nothing remains static for long in these
projects. What was assumed to be...rarely continues to be for very long as a project moves
forward. This is the real advantage of a virtual platform to work within.

Note, I did not describe any of this as high tech or even mention the C (CAD) word. In the
typical Golden Delicious flavor of all this there are built in tools (applications) which enable
manipulation of .eps as well as .tif, .tiff, .gif, .png, and the last one to use ...jpg.

I am close to purchasing a portable case of Golden Delicious to edit my real world occupation
presentations as well as edit my Flite-Metal application and finishing videos.

While warming one of the seat cushions within Best Buy's Apple crate, I found all the crates
come with almost everything you need and for the most part...its free. Yes, its in the Golden
Delicious crate...which until you realize they come with this they may seem more expensive
than an International Business Machine format.

Check it out, your modeling ROI will benefit.

[givmeasmoothy]

How do you guys build these things with foam. Do you make the frame with balsa then put the faom on. Thats wild how you make these things. I need a book on scratch building. Cant wait until flight-metal gets done and hope he puts a video of flight.

[Flite-Metal]

Originally Posted by givmeasmoothy

How do you guys build these things with foam.

With no intention to steal anyone away from David's 1/16th B-47 thread...

The 1/10.2 B-47E-IV thread was created to explicitly illustrate an answer to your question.
Literally, all you need do is replicate it and you'll have a 1/10.2 B-47E-IV.

http://www.wattflyer.com/forums/showthread.php?t=52194

David's B-47 is going to have six edf units and in reality will be much more scale than mine
because of its smaller size will enable a much lighter AUW.

Dave, having worked for Boeing and around B-47's has a mind's eye with the familiarity few
modelers have an opportunity to enjoy. On my thread, Joe Martin flew his designed from
scratch 80" w/s D version...in 1962. Joe designed exclusively from photos.



Follow David's thread and drawings I assume he will post along the way and you can easily
and quickly, more quickly than either he or I, build your own.

[Capt. Midnight]

Originally Posted by givmeasmoothy

How do you guys build these things with foam. Do you make the frame with balsa then put the faom on. Thats wild how you make these things. I need a book on scratch building. Cant wait until flight-metal gets done and hope he puts a video of flight.

Hi 'Givmeasmoothy'!

I'm definitely not the one to answer your inquiry on how to build with foam, as I only use it very infrequently when there are complex shapes/surfaces to model. When I do use it, I just carve/sand to the shape I'm trying to model, then (usually) cover with very light glass cloth to protect the surface from dings and dents.

I believe there is a good book on building with foam; I don't have the title handy, but a Google search should turn it up very quickly. Also, there are a number of forums/threads on building with foam, so I'm sure you could get some good advice/help from them.

Yes, I certainly agree that it will be wonderful to see a video of Flight Metal's B-47, as it is sure to be a sooper model.

Dave P.

[Flite-Metal]

Guys when we get there, we'll get there...no rushing our 1/10.2. I am anxious to see David's 1/16th. I am curious...what are you doing for landing gear retraction?

[Capt. Midnight]

Hi Ed!

As far as LG for my model is concerned, I have not done too much planning, except to evaluate their space requirements, etc. My 'general' plan is to use linear electric actuators for the retract mechanisms (I don't like the air-driven actuators); there are a fair number of 'miniature' actuators available from various sources, so will continue evaluating various options. On other models (TSR 2, F-100D) I have used Lado retracts, but apparently Lado is being sold or going out of business, so will have to find some drive units from other sources.

Regards,

Dave P.

[Capt. Midnight]

Hi B-47ers!

I've made a little progress on the empenage for the model; a couple of photos are attached (I hope). Next is the fuselage - may have to buy a new 36-inch hollow-core door, as the existing one is pretty will cut up.

Cheers,

Dave P.

[Capt. Midnight]

Hi B-47ers!

I've started on the fuselage - I'm building it upside down with a 1/2-inch alum tube along waterline 131.5; the building surface corresponds to WL 200. Each station/frame will be positioned and glued to the top/bottom/side 'longerons'; once this is done, I could rotate the fuselage (if necessary), and add enough stringers to keep the fuselage in shape. Some of the frames will be laminated for strength (for LG/retract mounts, wing torque box, etc. So far, it seems to be going reasonably well, though it is a bit tedious and time consuming.

Quantitative data/measurements available on this dang airplane is very scarce, and some of the drawings from tech orders are obviously in error. However, this isn't unusual for these 'vintage' aircraft, and isn't a fatal show-stopper.

I'll get a bit further along and will add some additional photos.

Cheers,

Dave P.

[Flite-Metal]

Dave,

Did you receive the email I sent?

[Capt. Midnight]

Hi Ed!

Yep, sure did - sent an email to your email address just a few minutes ago.

Cheers,

Dave P.

[Flite-Metal]

What can I say, this is how bad it is. You are fortunate they took a little more interest and
resulting resolution...in your copy of it :^)


By the way...the airfoil shown above this section on BAC's drawing is an accurate airfoil. It's a reflex with a nice long midpoint to trailing edge to accommodate the flaps...

[Flite-Metal]

Dave,

Thanks for the expedited copy at 200%. It solved my problem...here's a
gold star to hang in the background of your build

Thanks again!,

[Capt. Midnight]

Hi B-47ers!

The skeleton of the fuselage is mostly done - see attached photos. It was no fun, but the good news was that virtually all the station/frames seemed to come out quite well. One of the problems was that the Boeing 'desk-model' drawing on which my version is based was poorly scanned (by Boeing Archives); this led to some uncertainty in the actual lofting of the lower aft fuselage mold line on the keel. In the end, I just faired in some ogives and a straight section, and it seemed to match the fuselage station/frames; a few had to be adjusted at their lower intersections with the 'keel' longeron. Now the hard part: adding enough stringers to keep the darn thing in alignment, without introducing significant strains - or, at least balancing the strains around the circumference and length of the fuselage.

More later.

Dave P.

[Flite-Metal]

*Hal courtesy of MGM Home Entertainment's "2001 A Space Odyassy
http://www.imdb.com/video/imdb/vi2388329497/

Dave................

Dave.............................................. .......where is your Star

Dave...............................its not nice to ignore a Gold Star....

Dave...............................compliance to protocol is essential...

Dave........compliance is essential to the fabric of the universe...

Dave.................................Dave......... .........................Dave

Dave...compliance is essential to stability and continuity of the universe.

Dave................why are you being incontinent

Dave.........

Dave.........remember you are being observed........

Dave.........we are in here watching.................

[cyclops2]

You can tack glue 2 stringers at a time each directly opposite the other. Make sure you DO NOT use a water based glue. A small dot of CA is enough on only any 2 touching surfaces. Save most of the NOTCH area for the wood glues.
When you have the all of them CAd in place, then lay on the water based stuff directly opposite each other. I find Titebond II great, as it does not ever dry as brittle as Epoxy. Strong & givee is my best description. It will form small fillits. The stuff looks massive and heavy but is mainly water weight.
If you are worried about warps. Find some Angle Steel pieces and C clamp the then across the frames when you do the final gluing. I use 3/4" x 3/4" strips. That does stop 99 % of the warps on some of my impatient glue ups.
Forgot to tell you to cut up a bunch of gluing blocks so you can C clamp the frames to the Angle Steel strip. Not a quick job, But very accurate.

[Capt. Midnight]

Hi Cyclops!

Thanks for the suggestions! I normally do as you've suggested (2 stringers at a time on opposite sides, etc.); and my building jig does do a good job of keeping the fuselage from turning into a banana. I've also pre bent some of the stringers in the nose area to keep the distortion stresses to a reasonable minimum. I also use Titebond II for certain areas, and have noted the same characteristic (sandable, vs the dang epoxy and CA). I'll add some additional photos when I get a bit further along.

Cheers,

Dave P.

PS to Ed/Flite Metal: thanks for the images; I'm just not all that adept at figuring out how to load them into these messages. I like the HAL image, and the gold star, so have printed them and pasted in my computer 'hangout'. Sure hope I don't have to go 'outside' to get the pod-bay doors open ...

[Flite-Metal]

Dave,

One quick question I have to run. Will Depron as a skin around your stringered fuse be of high enough strength to negate planking and sheeting? This of course would not be for the nose...

[Capt. Midnight]

Hi Ed!

I kinda think the Depron would be plenty strong enough, but my problem is I don't have any of the stuff, and have never done any building with it. One of the guys in my club (a transplanted Englishman, and retired Boeing Commercial aircraft fuel-system expert) has done extensive building with Depron. He lives about 10 miles from me and I've visited him and observed his very skilled use of the material, and seen one of his models (an EDF) fly; it was an excellent model/flier!! The one thing that I had some reservations about was the resulting overall finish of the models; some seams showed, and some of the surfaces were kind of 'wavy' (not a good descriptor, but can't think of a better term). Most of his models were relatively small compared to, say, your 1/10th B-47. I've seen (on some other forums) larger models built more/less completely with Depron, so I'm sure with some patience, one can get a good finish, and strong structures.

There is no local source for the Depron material in my area, so it seems that you have to buy a fair amount of the stuff, even though I noted that some sources sell 'packages' of the material with several sheets of various thicknesses.

Probably my main reservation is I'm not sure I've got enough patience to learn a new building/finishing technique.

Are you planning to use any Depron in your model?

Cheers,

Dave P{.