Well I took the plunge and bonded in one of the tanks last night.
The job seemed to go okay.
First off I sanded down the raised solder blobs so that the tank would be as flush as possible with the inner of the wing. This should maximise the bonding surface.
Then I did a 'dry run' - installing the tank without the PU foam on it to make sure it would slide in easy and not catch on anything - just as well I did, there was a little tweaking required to make it fit easily. Actually I found once it was covered in the PU foam it slid in easier. But you don't want to find something catching when the tank is covered in PU - best to find out these things in advance.
I also did a test piece first to get a feel of the working time of the PU foam - all the info on the pack is in German and Russian so that wasn't much help. The photo below was taken after 30 mins. The blob this started with was less than 20% of the volume of what you see here - so it does expand up quite a bit. I wouldn't want to spend longer than 5 minutes before it goes in the wing as the foam starts to take on air bubbles at around the 5 to 10 min mark.
The photo of the PU on the tank was taken before I put about another 50% more PU on it - better to have too much than too little here. May as well use up all the PU in the bottle - hold it up to a very bright light to see how much you have used.
Next step is to bond in the root end edges with 40mm tape. Then the even more scary job comes next of drilling holes in the wing for the drain and fuel cap. Gotta buy a few hole saws before I do that.
 |
| Tank before covering with PUR foam |
 |
| Partly covered with cris-cross pattern - I added another 50% after this |
 |
| Test piece after 30 mins - expanded about 500% at this point |
 |
| Tank in. Edges to be reinforced with 40mm tape. |
Very nice work bud......amazed by the speed of progress. I heard on the grape vine that Pete Wells has had several engine failures with the UL Power this year. Have you heard anything about this and are you still looking at ULP?
ReplyDeleteRegards Krishna
Thanks man.
ReplyDeleteSo far I am keeping to my 12 hours per week average so it should be done in about 2 to 3 years, but I'm in no rush.
Actually enjoy the building more than I thought I would.
Only one UL engine failure that I know of this year - crankshaft failure. Like most things there is more to the story - I'll say no more than that!
Pete does give these engines a maximum workout with the display flying they do. I still think they are better than the alternative - a Jabiru. But like most things I am keeping an open mind - the engine decision can be left for another 2 years if need be.
Cheers
Andy