Bentley BR2

[joerom]

Having made the proper style main mount, it is looking more like a BR2..Next I needed a stand, and this also means I needed an extension for the crankshaft, and also a proper style sleeve nut that secures the main mount to the crankshaft..If you look at the picure below, you will see on the left, the new stand and extended crankshaft and longer proper looking sleeve nut..On the right is the original design that was made by the previous builder..The main mount is nothing like a BR2, and the very short sleeve nut looks wrong..NOTE: before I go any further I would like to say that the engine that was being made by the original builder would have worked the way it was, it just would not have looked like a BR2 should, and as far as I am concerned, it would just have been a 9 cylinder rotary engine, and that is not what I was after..I was originally going to make 2 of everything and have 2 finished BR2's, but with all the figuring and changing that was necessary to do what I wanted, this would have been an even much longer project, and at being 73 years old, that idea seemed like it was lacking something...……

I fashioned an extension for the crankshaft that was threaded on to match the 40TPI..It was a sleeve that threaded on the crank after the newly fashioned sleevenut to secure the main mount..Notice the difference in the sleevenuts on the left and on the right in the above picture..I also then threaded the end of the extension that goes through the stand at the rear, onto which I made another nut to hold the rear of the engine to the rear of the stand...These are shown below..

So, with the addition of the previous parts, I think it looks like a proper Bentley BR2 now, as compared to what the original builder intended, and the following pictures show that...

Moderators,I hope I am not adding too many images, as I do not know if there is a limit...…...

 

[kvom]

More the merrier

 

[RonC9876]

I built mine in 1/8th scale. It is amazingly powerful for it's size. The only real problems were with the ignition. When first started it was equipped with spark ignition and it ran well until the rings seated and the compression came up. At that point, spark would jump externally everywhere but at the plugs. I tried all manner of insulation ideas and even thought of lowering the compression with shorter rods, pistons, or whatever to stop the external arcing. I finally decided to switch to glow ignition. This worked out well. The segmented commutator was replaced with one with slip rings and glow plugs were fabricated using elements from standard glow plugs welded into 5-40 diameter bodies. The engine can be seen running on YouTube at ronsmodelengines/BentleyBR2.

 

[joerom]

Hello,
I have seen this engine before and really liked the smaller size..Actually, I am an admirer of all your engines..I always check you out at Cabin Fever....
Joe

 

[RonC9876]

Thanks, Joe. The quarter or now one third scale models are hard to transport to the shows. Especially when you have as many engines as I do!

 

[joerom]

Although I am a long way from needing a carburetor, I wanted to see what it would look like with one because of that being another thing that would make it more like the BR2 I am looking for..So I did the basic carb, and it has no internals yet, and also needs some additional exterior finishing..The pictures below show this.. It is of proper size in and out, and now makes the engine even more BR2..When I first started this project of making this thing look like it should, I was not sure of the outcome, because it was so far from scale looking..The brass pipe lying on the bench by the stand will be mounted on the carb crosswise..This would have gone through the airplane and exited through the body..Now I am pretty pleased with what I have so far, and will continue along with all the boring work to follow..

Next, I have squared off the holes for the intake pipes like they should be, and also mounted the main gear..I did not take any pics of this, but it was cut the center out of the purchased gear, and press it on, no magic there..

The last thing to do here was drill and tap for the cover on it, and that is done now...…..

 

[58tux]

Looks like you are making some great progress. Keep up the good work. Seeing these pictures I think that I will get my BR2 out and run it today.

Rich

 

[joerom]

The next thing I wanted to do is to slim down the rods that were there..They had too much metal on them and you would not be able to install the rod assembly in the crankcase in one unit..You would have to assemble the rods in the case one at a time..I want to build it outside and then install it, hopefully..You can get an idea of what I am doing by looking at the picture below..The one on the left is as I got it, and the right one is trimmed some..The ends need to finished up a bit yet, and this is one of those boring jobs..There won't be much to show until I get some of this stuff done..After this is all done, I will make the bearing carrier for the master rod...

 

[joerom]

I did remove some more metal overall from the rods, than in the last picture..This was because I just did not get the right numbers the first time..I also rounded the ends some more because of excess metal..Now all the rods are slimmer and even all around..I stuck them in them master rod to see what they look like..This is the first time I actually saw all the rods together as a unit..Next I will finally get to the bearing carrier for this..

 

[stragenmitsuko]

amazing craftmanship

 

[John Roberts]

I am also building a BR2 but based in the Blackmore design. I also first modelled the assembly in CAD as there are so many dimensional errors in he Book.
I have completed the crankcase, cambox ,thrustbox, nose piece and currently making the con rods.
I would be very interested in finding out what valve springs to use. I see that tapered ones are available but have no idea what wire size and general dims of this item. Any advice would be appreciated.
I hope to make the induction elbows from solid on my CNC mill but as yet having difficulty modelling these parts. Anyway I am a long way from making these.
Just made a slotting attachment for the lathe to tackle the key slots needed. Not sure how well it will work on steel.
Lots of challenges ahead!

 

[joerom]

Hello John,
The BR2 seems to be a popular model..If you are going the full scale route, I believe that the flat springs are explained in the book, and there are many pictures..I would think that there are ready made springs that can be used, and would involve some experimentation...I am making changes as I go..
Mine is 1/3 scale, so any thing as far as sizes and general dimensions would not apply..This is an ambitious project to say the least, but one of the better ones..
Maybe another builder can add some info here as far as springs for the 1/4 scale version...……..

 

[joerom]

An Observation,
When I first took on this project, I was not too sure about the 1/3 scale..I originally wanted the 1/4 scale version..But, I went along with it because of that was what it was, and being 73, I figured this would be a quicker way to have a BR2..After working on this thing for a while now, I am realizing that it is actually easier to work in a larger scale engine..Although I am not saving time by having a part built engine because of all the changes I am making, the changes seem easy mainly because of the size..I am actually liking the 1/3 scale now, so much so, that I already have my next project lined up, and that is a 1/3 scale Gipsy Major that was originally designed by Krieger..
I do still very much like the smaller scale engines, but for me now, bigger is easier, probably because it is easier to see!

 

[petertha]

Not to detract from your BR2 post, but is this the 'next project' you mentioned? You mean you have the castings or will scratch build from the design? Cant wait in either event.
http://modelengineeringwebsite.com/Gipsy_Major.html

 

[joerom]

Yes, that is the engine..I have the castings, and I think it is a greatt looking engine, and a great scale project....
I will start on it while I am working on the BR2, mainly to keep the interest up because my ambition levels are declining as I get older..I also have other projects, and will work on them also, and if I have a lot of unfinished projects, it does not matter, as long as it keeps me off the recliner..
I will move to Engines From Castings when I start that project, even though it is also a long term project..Nothing saying I can't have 2 projects going(or maybe even more).……..

 

[John Roberts]

I intend to stay true to the Blackmore design apart from the valve springs! There seem to be many others who have opted not to make their own from flat spring steel. This looks like a hit and miss affair getting the hardening correct.
Tapered coil springs still look right in this engine.

 

[joerom]

I agree with using the coil springs..There is enough to do on this engine without making scale springs..The flat springs look like they would be a lot of work to get right..You could also add them at a later time if you wanted..
This is a hobby, so do what ever feels right to you...………………….

 

[joerom]

I am now working on the bearing carriers for the master rod, two are needed..In the first picture I am getting them to size..Then once sized, they are cut off..The last picture shows how they will go and are just loosely placed...The bearings will press fit into them and they will be mounted with screws into the master rod once I finish them..They are a snug fit in the master rod...
After that, I will finish the crankshaft by adding the oil line from the main mount to the main journal..I also need to add some oil lines because of what I changed to make this all work out how I wanted it to be..

 

[lantain1982]

Regarding valve springs on the Br2 [1/4scale] I tried, without acceptable results to make the flat spring item. I found it very difficult to obtain any form of consistant results, bearing in mind that the springs must collapse fully to achieve full valve travel opening. I switched to involute wire springs. May not look as good but I accepted a practical solution. For interest if you are looking for a source of flat strip, go to your local wrecker and obtain an old seat belt retractor, you will have enough strip to last a lifetime. You will have to reduce the width to suit.
All the best with the BR2, when you fire it up for the first time its a moment you will remember.
Cheers.

 

[joerom]

I will go with regular springs to get this thing running, when the time comes..Maybe later, just for fun I may try the flat springs..I am the type, that the whole challenge is if I can do a certain project..Once the project is done, no matter what it is, I lose all interest and go on to the next project..The more difficult a project, the better I like it...
I do like all thoughts and input on all your projects also, even if not directly related...