Bentley BR2

[joerom]

Hello to all,
I was away from this hobby for quite a while..I am 73 now and decided I needed to play again..I came across a partly built Bentley BR2, well actually 2 of them..They were being made in 1/3 scale..It appeared that there was quite a bit of work already done, and it looked pretty good..When I received them and started going over everything, I started to see that there were many things that did not suit me and some things left me puzzled as to the original builders intentions..The first thing that I realized is that the 1/3 scale did not follow through, and as an example, the crankshaft was short as to what it should be for the scale, and then the main mount was nothing like what a BR2 should look like..


OK, there is a brief summary of why I am doing what I am doing..I want to bring it closer to scale, and will change what I think necessary to do so..I will post pics as I go and will start with a comparison of the way it was and the way it will be..On the left is the way it was..Disregard the date,never setup camera..

In the first picture above, you will see that the crankcase was much thicker than what it should have been..There was plenty of metal, so I was able to narrow it by .400 total..It made a big difference in the look already, because it also tapered it up from the front and rear cover, look at the pics..

The above picture gives a rough idea of what I wanted to do....

I had to re-taper it to meet the cylinder ..

You can see how it changed it making it much closer to what it should be..
That is a good start for now, and I will explain all other changes including making the main mount look like a BR2...….Joe

 

[rweber]

Do you have plans on which you are working, or is it all own design?

 

[joerom]

Hello,
There are plans available for the 1/4 scale version..There is also a book..I believe there are some on ebay now, just type in Bentley BR2..The plans are available in England somewhere, and do a search for the same..I am just scaling up the available plans, plus making changes necessary on my own to meet the scale engine that I want...…
Joe

 

[rweber]

For your information, in ME Issue 4589 started a series of articles where someone builds a BR2 composed with the best of both plans, the Blackmore book and the plans from ageless engines.

 

[58tux]

Joe
Having built a 1/4 scale Bentley I know that there will be several challenges especially changing the scale of the engine and starting with someone else's work. I will be following your work. There will be no thrill like when you first hear and see the engine run.
Rich

 

[joerom]

Hi Rich,
That looks like some very nice work..I can really appreciate what is involved with anyone who takes this thing on..I have done a few projects in my time, and some very involved..When I took on this project, I did not realize how far from scale it was until I received it..What I am trying to do is get it as close to scale as possible with what I have to work with..I have 2 of them, and my thought was to make two of everything and finish both engines..In reality, that is not going to happen, because there is too much changing to do to make it more scale than originally thought, and I am 73 and have more projects I want to finish....So, I will concentrate on only the one for now..I have it much further than what is shown here, and I will post much more here..Later on today, I will add more info here of my progress...
Joe

 

[joerom]

The next thing I had to do after thinning down the crankcase was to shorten the front crankshaft extension or Maneton, which is what the master rod rides on..Fortunately for me, the previous builder had threaded the part I needed to machine into the extension..It took me a while to figure that out because it was done so well..In the following picture I am machining to length the part, and then followed by having to match the taper in it to fit back on the main crankshaft..That all went well..

Then after doing that, I had to match the master rod which rides on the maneton to the maneton..This was machined on both sides to a depth needed..It was also figured to match the 2 ball bearings that will go into it in a special carrier..

In the following picture, you can see the master rod as it will sit in the crankcase..It is waiting for the bearings and carrier to be made..

 

[joerom]

Hello again Rich,58tux,
I am curious as to what you did for the elbow's on the intake on your 1/4 scale engine..
Joe

 

[HWF]

Joe,
I am very happy to see an active thread on building the BR2. I am planning to build one as well. I have the 1/3 scale plans from Ageless Engines and the Blackmore book.

I have opted to go with the 1/4 scale which more closely follows the actual engine design. I have been modeling the engine in 3D CAD with the intention of CNC machining the parts. I have just started working on the CAM programming of the first part.

I have a grandson who is coming up on his first birthday in Dec. His name is Bentley which is what got me thinking about this project. I have found someone at an RC club in Georgia where my grandson lives, that is willing to build an RC plan to house the engine.

So I look forward to following this thread and exchanging notes.

I am planning to make the elbows from a solid billet on the CNC mill.

I hope that I am up to the task and hope that mine turns out as nice as Rich's.

The Ageless Engine design seemed to be focused on ease of fabrication rather than authenticity. A lot of the parts that were originally made from steel were made from aluminum in the Ageless Engine design and I would be concerned about putting that engine into an RC model. The 1/3 scale would also be a major issue.

Rich, I am curious, the Blackmore book calls for the use of a lot of mild steel for his engine where I would have thought that stainless would have been more appropriate. There seemed to be some amount of compromise to enable manual machining with small home shop machines. What materials did you use and what equipment did you use for fabrication?

Howard

 

[joerom]

Hello Howard,
I am happy to exchange notes or whatever to anyone attempting to build this or any engine..We are always learning..I am also thinking about CNC for the elbows, and am just starting to get together a machine to do it..I am more use to doing the hard way though, and still may do so..To me, it was always the challenge to see what I can do, and the more difficult the challenge, the more interested I become..
Although mine will not be full scale as the Blackmore book because of what I am starting with, I will make it as close to scale looking as I can..One thing we all need to keep in mind is that this is a hobby, and what ever anyone does that is to his liking, is all good...So, do what makes you happy.....
Joe

 

[HWF]

Joe,
I can agree more. For me it is all about learning new things. There is lots to learn.
For me it all the ins and outs of my CAD and CAM software as well as my new CNC controller and mill.

It is always good to have a project to help you push your limits.
Howard

 

[58tux]

Joe

The intake manifolds were the most challenging parts of the engine to make. The upper elbows I cast following the instructions in the Lew Blackmore book. I Must have cast 20 to 30 pieces before I got nine good ones. I discovered that I do not know anything about casting Al. The lower pieces I machined from the solid. When I built the Bentley I did not have any CNC capability. Also there is no stainless steel in the engine. The heads and cylinder liners are 12L14 steel. The cams and cam rings are 4140. The rest of the engine was made from what I had laying around, mostly 1018.

 

[joerom]

Hi Rich,
You should be proud of what you have done..The work looks great..I don't know if anyone ever made castings commercially for it, but it would seem like a good idea, although it would not help me in my scale....

 

[joerom]

Now I am going on to make the main mount..The one the original builder made does not look like a BR2 mount..I needed to find gears to fit in a certain space with the correct ratio to keep it looking like I wanted..I finally found a set of gears that would work for me, and there is just enough room in the main mount for them to keep the outside looking right..I first machined the inside just enough to fit the gears and have them rotate with each other..The gears still need to be modified later to mount them..The following picture shows this...

I then proceeded to machine it to shape inside and out..The three small holes you see in the mount are for the two magnetos and oil pump that will be mounted later..They will need to be opened up to the size needed..They are only there now to get the centerlines for the gears for mesh..The following picture shows the mount, which now looks like a BR2 mount..It still needs some finish work and holes..

The next 2 pictures shows it mounted..The sleeve nut that holds it on is wrong and the crankshaft still needs to be extended..

 

[kvom]

I have seen the Ageless engine version at various model shows over the years, and Lee claims it's "easy" to build. haha

I would think aluminum for weight over steel would be an advantage if one were to try to fly the engine. That said, since the engine itself rotates there will be a very considerable side force during climbs that the rudder would need to counteract.

 

[joerom]

I have never seen the Ageless Engine version in person, but have looked at many pictures..I guess if you consider what the Blackmore version needs to construct, the Ageless Engines would be easier, but by no means easy.....
A lot of mine was made with aluminum, but I am not concerned with weight..I made the main mount with 12L14..Being 1/3 scale, that probably would not matter if in an airplane because the plane would be huge..I figure this one would have a 36" prop....

 

[joerom]

kvom,
What is your preference in all this stuff...

 

[HWF]

Here is a video of the Blackmore version used in an RC model. When complete the 1/4 scale version of the Blackmore is about 16 lbs and will use a prop of about 27". I have not seen any implementation of the Ageless version that has been used in an RC model.

 

[joerom]

It would be really neat to fly an engine like this that you made, but I am not that brave..I have flown RC and also crashed some, so I can really appreciate someone doing that..It also shows that it has real power and is more than just a model and the craftsmanship of the builder....

 

[Cogsy]

I feel the same way - I'd hate to see an engine with so many hours of building in it destroyed by something I couldn't control. I once lost an airframe that was less than 10 flights old when the aileron servo stopped responding mid-flight. I made it back to the field on the rudder but it dipped the left wing and I couldn't get it back so it went in hard. That servo still annoys me when I think about it - it didn't strip a gear, just failed electronically - but that airframe only took me maybe 75 hours to build, nothing like one of these engines.