Bristol Blenheim (oz11253)

 

Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - plan thumbnail

About this Plan

Bristol Blenheim. Radio control scale model WWII bomber, for electric power using 2x Speed 600 motors, and minimum 3 functions. Approx scale is 1/10.

Discontinued kit from Balsacraft (Model Designs).

Note main plan sheet does not show engine nacelle construction (or indeed the wing ribs).

The kit included vac-formed moulded parts which formed the rearward (complex-curved) section of each nacelle, see morepics 003.

Direct submission to Outerzone.

Note photo of completed Bristol Blenheim model was found online at https://www.rcgroups.com/forums/showthread.php?33033-BalsaCraft-Bristol-Blenheim

Update 24/06/2019: Added missing sheet #2 into the planfile. This shows nacelle layout, stbd wing panel layout, wing spar parts etc. Thanks to Karsten.

Update 27/07/2020: Added kit review from Sailplane & Electric Modeler, September 2000, thanks to RFJ.

Quote: "In Review: Balsacraft Bristol Blenheim, by Henry Holcomb.

British pilots loved it. Designed as a fighter-bomber, the Blenheim was maneuverable, easily looped, and in the early days of the war, it was the closest thing the British had to a long-range fighter. As a twin, with a Browning machine gun in the port wing and twin Vickers in the turret, it could out-run, and out-shoot most of the world's fighter planes of the day. In fact, it sounded the death knell of the bi-wing 'persuade ship.' It was the first British aircraft of the war to cross the German frontier, and it was quite successful at beating off attacks by German BF110s. The Blenheim's turret gunners discovered early on the BF110's Achilles heel - its twin-rudder tail. They got pretty good at shooting this rather weak appendage completely off.

As the world's combatants got down to the business of killing each other, fighter designs progressed rapidly. By 1942, the Blenheim was outclassed and was a rather easy kill when not protected by fighter escort. But, it was the Bristol Blenheim on which the British warriors of the air cut their fighting teeth.

1/10-Scale Hobbico imports this 1/10-scale Balsacraft model. It is the famous Blenheim. Except for some nicely vacuum-formed parts, the kit is all wood. Many parts are CNC-cut from light plywood. Included is a com-plete hardware package and a set of scale wet-transfer decals.

The Wing: The wing spar is a simple beam, pre-cut from 1/8-inch-thick balsa. The section between the motor nacelles is doubled with 1/64-inch ply and set on edge. The ribs are in halves with the front halves glued flush to the front of
the spar, the rear halves to the back.

Instead of the 1/64th-inch plywood doubler I used 1/32-inch, but not because I considered the design weak. I was installing landing gear, so the stronger, 1/32-inch doubler would support it.

The plans show a single servo in the center of the wing to drive the ailerons. I opted for two servos. I used Hobbico's CS-35 High Power Mini BB servos. I shrink-wrapped them with sections of battery shrink tube and then glued them in with Zap A-Dap-A Goo.

Motor Installation: The twin motor nacelles are made by fitting round formers over plywood boxes. Then, 1/64-inch ply is wrapped around the formers. Vacuum-formed rings are then glued to the front. The Great Planes Goldfire, Speed-600 motors slide in through the front of these boxes. I was definitely impressed with the design of these nacelles and the perfect fit of the motors.

Fuselage and Battery Installation: Most of the electronics are installed in the wing. You will understand why as we build the fuselage. Here's how I did it.

The manual contains some excellent isometric drawings. Like the motor nacelles, the fuselage is based on a plywood box. The formers, giving the fuselage its rounded shape, are slipped over this box, glued in place and then sheeted. I mounted the battery pack in this box by turning the top section of it into a hatch. When you build your plane, construct the box according to the plan, but do not glue the top of the box (Part B2) in place; just fit the tongues into the notches. Slide-on and glue the formers. Then cut through the sides of the formers and the top will lift away, providing the framework for a hatch.

I installed a 1/16-inch ply floor in the box for additional battery support, With only seven cells, I still had to move cross-members out of the box. The rudder and elevator servos and Rx switch mount at the rear take up more of the already limited space in this box. The space problem was complicated still further when I decided to increase the number of cells to 15.

The rudder and elevator servo wires and Rx switch wires must go through an opening in the box into the wing to where the receiver and ESC are locat-ed. Wires from the ESC will come from the wing through this same opening to be plugged in the battery pack. Like most mid-wings, a large section of the fuselage is mounted to the bottom of the wing and becomes part of it. This actually strengthens the wing. By cutting through the bottom of the wing sheeting in this area, I was able to uti-lize this additional fuselage depth to mount the receiver, Rx battery pack, and ESC. I used Hitec's new Super-Slim receiver and mounted it as far from the ESC and battery wires as space allowed. I soldered a fuse directly into the ESC wires.

How Many Cells? The manual calls out a pack of seven 1700 mAh cells, wired in parallel - manufacturer's estimated weight is 66 ounces. If you go this route, you need an ESC capable of handling 40 to 60 amps because Speed-600 motors draw 20 to 30 amps each. Frankly, sucking 40 to 60 amps out of a seven-cell pack will result in 3 minute flights, or less..."

Supplementary file notes

Instructions part 1. Text, 8 pages.
Instructions part 2: Illustrations showing fuselage build, nose build, nacelle construction, parts sheets identification, materials list, colour scheme notes. 10 pages.
Review.

Corrections?

Did we get something wrong with these details about this plan (especially the datafile)? That happens sometimes. You can help us fix it.
Add a correction

Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - model pic

Datafile:
  • (oz11253)
    Bristol Blenheim
    by Pete Nicholson
    from Balsacraft
    1998 
    60in span
    Scale Electric R/C LowWing Multi Military Bomber
    formers incomplete :(
  • Submitted: 10/06/2019
    Filesize: 1014KB
    Format: • PDFbitmap
    Credit*: KarstenLundeHansen

ScaleType:
  • Bristol_Blenheim | help
    see Wikipedia | search Outerzone


    ScaleType: This (oz11253) is a scale plan. Where possible we link scale plans to Wikipedia, using a text string called ScaleType.

    If we got this right, you now have a couple of direct links (above) to 1. see the Wikipedia page, and 2. search Oz for more plans of this type. If we didn't, then see below.


    Notes:
    ScaleType is formed from the last part of the Wikipedia page address, which here is https://en.wikipedia.org/wiki/Bristol_Blenheim
    Wikipedia page addresses may well change over time.
    For more obscure types, there currently will be no Wiki page found. We tag these cases as ScaleType = NotFound. These will change over time.
    Corrections? Use the correction form to tell us the new/better ScaleType link we should be using. Thanks.

Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - pic 003.jpg
003.jpg
Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - pic 004.jpg
004.jpg
Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - pic 005.jpg
005.jpg
Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - pic 006.jpg
006.jpg
Bristol Blenheim (oz11253) by Pete Nicholson from Balsacraft 1998 - pic 007.jpg
007.jpg

Do you have a photo you'd like to submit for this page? Then email admin@outerzone.co.uk

User comments

Additional pics thanks to Karsten [more pics 003, 004].
Mary - 20/01/2020
For more background see the Balsacraft Warbirds Appreciation Thread on RCGroups at https://www.rcgroups.com/forums/showthread.php?128507...
MPF - 19/02/2020
Add a comment

 

 
 

Download File(s):
  • Bristol Blenheim (oz11253)
  • Plan File Filesize: 1014KB Filename: Bristol_Blenheim_oz11253_.pdf
  • Supplement Filesize: 1609KB Filename: Bristol_Blenheim_oz11253_instructions_1.pdf
  • Supplement Filesize: 1729KB Filename: Bristol_Blenheim_oz11253_instructions_2.pdf
  • Supplement Filesize: 5296KB Filename: Bristol_Blenheim_oz11253_review.pdf
  • help with downloads
 

Notes

* Credit field

The Credit field in the Outerzone database is designed to recognise and credit the hard work done in scanning and digitally cleaning these vintage and old timer model aircraft plans to get them into a usable format. Currently, it is also used to credit people simply for uploading the plan to a forum on the internet. Which is not quite the same thing. This will change soon. Probably.

Scaling

This model plan (like all plans on Outerzone) is supposedly scaled correctly and supposedly will print out nicely at the right size. But that doesn't always happen. If you are about to start building a model plane using this free plan, you are strongly advised to check the scaling very, very carefully before cutting any balsa wood.

 

Terms of Use

© Outerzone, 2011-2020.

All content is free to download for personal use.

For non-personal use and/or publication: plans, photos, excerpts, links etc may be used, provided that full and clear credit is given to Outerzone with appropriate and specific direction to the original content i.e. a direct hyperlink back to the Outerzone source page.

Unauthorized use and/or duplication of this material without express and written permission from this site's owner is strictly prohibited. If we discover that content is being stolen, we will consider filing a formal DMCA notice.