Red Baron Fokker Triplane-Issue 73,Carburettor bracket.

[wonwinglo]

Issue 73 contains the parts required for the carburettor support bracket,what seems like a simple operation has left questions in doubt as to if the assembly is in the correct place ? the engine crankshaft exits with a slight protusion at the rear of the ply laminated front bulkhead,however for some unknown reason the carburettor support centre hole does not line up with the shaft ? why this is so placed is not known at this time or what exactly goes into the hole? for the sake of demonstration here I have merely lightly tacked the bracket together for the time being,no doubt all will be revealed in the near future when any issues regarding its alignment can be sorted out.

Another view of the bracket showing its position according to the instructions,something certainly does not look right here ?

While I was checking this I decided to place the rotary engine in position to see how it looked,what occured to me here is the way the engine droops on the floating bearing,some extra support will need to be added to bring the crankshaft in line,unless some provision has been made for this factor ? one possibility would be to bush out between the bulkhead and the rear geared portion of the engine,a sort of large diameter spacer assembly perhaps ? once again nothing can be achieved until later on when the front assembly is completed according to Hachette's instructions.

 

[wonwinglo]

Modifications to the carburettor support assembly-Issue 73.

http://www.wonwinglo.scale-models.net/id42.htm

I have prepared a tutorial on how my own carburettor assembly was modified,at the same time the engine droop scenario has been rectified with an extended bearing,I would stress that these are un-official mods and nothing to do with Hachette ! the system utilises as much as possible of the original parts and just needs a few pieces of brass or alloy tube.

Any questions and I will be pleased to answer them.

 

[adzam]

teh info you post in this model barry is superb ! makes me want to have a go :terrific:

 

[wonwinglo]

Red Baron Fokker Triplane-Improved modifications to the carburettor bearing support.

Here is a revised and improved version of how to drastically improve the Carburettor support bracket,as supplied by Hachette it simply will not work as supplied because the whole assembly is out of line,would be builders or those still who have not yet completed their models are advised to study these modifications carefully,my aim has been to use as much as possible of the original fittings as supplied,so here we go-

Issue 73 Carburettor Support backet (Modified assembly)

After giving this item a lot of thought the following method was devised,the idea was to use as much as possible of the existing assemblies,and with the addition of a few pieces of scrap tube and a standard threaded spiked anchor nut,whilst the mods were taking place the aft bearing assembly has also been improved upon so that it does not rely solely acting on the floating front bearing,this is how I set about getting this job done-

#1 First obtain a large spiked blind anchor nut,these can be obtained from model shops specialising in radio control aeroplanes,the nut forms the basis of a solid sturdy mount about which we can build on and improve the whole integrity of the engine itself,the anchor nut forms an excellent basis for something to build upon,almost anything similar with a flange will do the job,the idea is to offer added support for the engine shaft which has been cast too short.

You need to reverse the spikes so they bed into the built up circular ply pieces or alternatively drill small holes into the flange and use tiny screws if you can get hold of some,use slow drying araldite for extra security and make sure that it lies central and in line with the bearing,allow to dry overnight.

#2 The next important job is to make a bearing extension for the rotary engine shaft,to do this get hold of a piece of suitable brass tube ( all tube was purchased from a model shop or even god hardware shops should be able to help here ) cut it to the respective length which is achieved by trial and error dry fitting,this should be a force tight fit into the blind mounting nut,run a little thin cyno down the seam being careful not to get any in the main bearing,dont worry you will not shift this assembly believe me !

#3 Make the outer spacer main bush,once again a piece of tube,we have reversed the existing carb fitting because there is a flange on the end we want,on the other end simply file off the rivets so that it will seat firmly against the carb itself,see I told you we were going to use as much as possible of existing bits ! put a bead of cyno on the lip and hey presto job done,you dont need to mount the carb assembly yet.

#4

Here is another picture showing the existing part sitting inside the tube spacer.

#5 Mount the assembly over the inner bearing,but before you do this flood the void between the two brass tube walls with epoxy resin,this is not essential but will keep everything in line and assist in supporting the shaft.

#6 Here we are performing a trial fit with the carburettor assembly,no need to fix this yet but offer it up and make sure everything is in line.

#7 Make use of the support frames provided,one fits fine,the other needs to be shortened a bit to keep it in line,here also I am holding the tubes to get the final picture,these should now line up perfectly with the exit holes in the side of the fuselage,the assembly is solid,its a belt and braces approach but it works fine.

#8 This is how everything looks when assembled,the rotary now sits properly into a decent bearing and the extension brings everything into line as it should be.

On completion of the nose area and when you eventually receive the nose cowling, you will understand better the need for extra support,the front of the shaft fits directly through the cowl front via a brass bush,this bush needs to be trimmed a little at the front,it is also advised that you support the front cowling properly as this takes the full weight of the heavy replica Oberusal engine.

The pictue shows the engine assembly pressed fully home.