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Rob's Grumpy Tigercub build


Rob Ashley
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I have followed other MB Grumpy builds whilst my own has sat there waiting. No more excuses to get it done.

The story so far:

I started Christmas 17 and was hoping to complete in 4 weeks but things happened. Thankfully the MB 18 gifted me hope and I can now join in.

I enlarged the plan to 63" span to accommodate x2 OS 32 motors with fixed U/C.

Blew the plans up to size and drew the parts in CAD. I then CNC'd a kit to build and started over a year ago and made some progress.

Started with the nacelles which were simple to do followed by the wing.

Oh yeah this is my first thread so please be patient.

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​Thanks chaps - I had better go get some.

I appreciate I am one of a number of builders of this model so I know there will be much repetition. Anyhow I'm finding that doing this thread is keeping my motivation going, so hopefully I will finish this build. Tail feathers are ready for final sand and covering. When I cnc'd my kit a milled a tongue on the fin that slots into the horiz stab to ensure everything remains square.

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Also fitted the nacelles which didn't really need too much fettling.

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I think like most others who have scaled up I have opted for 1 servo per wing to allow for flaperons if required. Otherwise this will be as per Peter's plan.

 

Edited By Rob Ashley on 28/01/2018 16:35:01

Edited By Rob Ashley on 28/01/2018 16:35:46

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Hi Tim,

I did consider the split flaps/ailerons and also retracts having looked at yours, but in the end I decided to keep as close to the original as possible - save the size increase.

I started by using PVA for the sheeting, but having discovered aliphatic (Titebond) I am a total convert. I love the stuff. I found on cold nights the PVA just wouldn't cure properly and left a white residue. My workshop was not then permanently heated only with a calor gas heater when I was in it.

Also I think the Titebond grabs well and is much easier to sand.

Had an 'oh bugger' moment last night after I dropped a sanding block onto the wing - it's made a dent so there's my first ding.....

Rob

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Rob, I’m a fan of aliphatic too both the ‘ordinary ‘ and the super aliphatic which is nearly as good as wicking into joints as thin cyano. I like that a lot for fixing things in place that are difficult to hold/clamp. I even resorted to using thin cyano to stick some covering film into the cooling vent I had left in the cowl. Sadly I had not thought ahead enough and could find no way of getting the iron in the gap. Could easily have made it a cm wider as well.

Tim

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Ace,

I've not heard of that before so will try it when I get the chance - thanks. Sadly in this instance the sanding block (a Great Planes aluminium jobby) pierced the skin so I needed to apply some glue. With a light coat of filler I don't think it will show.

Tim,

Not sure if I can be of help for your cooling vent - I know there are others who have made suitable tips from soldering irons and there are smaller proprietary shoes but I guess if glue works then go for it. Alas not needed for IC as the cylinder head is in the airflow.

Thanks for the vote of confidence Peter.

Edited By Rob Ashley on 29/01/2018 14:45:33

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Well I think the phrase I am looking for rhymes with clucking bell.

One of the OS 32 engines I had intended to go in to my GTC has stripped the chrome piston liner and won't run. Oddly enough as it is out of production getting another is unlikely. It was fitted to another model (a scaled-up Tequila Sunrise another PM design) and it has struggled to start and didn't develop full power - then gave up the ghost. This is the second one of these that has done that. This leaves me with just one left.

So...right in the middle of carving the cowls to fit OS 32s I now have to change tack - I'm starting to think electric but while I ponder and give the problem a huge dose of chin sctraching I will give the fuselage some attention.

Tim, I always find I need something I 'should have bought ages ago' in every project. Only if I buy it I seldom need it again. Your GTC is looking great btw.

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That's not a bad shout Peter - I've not used SC engines before so they are certainly in the mix.

My other current thought is electric with the batteries in the nacelles - this would keep the wiring easier with less modification required. Have to admit I'm 60 elec / 40 IC which is a little scary as I consider myself an IC man.

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Tim,

To answer your question in your thread, it was me - I started in Jan 17 and made a bit of progress for 3 weeks. But that came to a grinding halt until last Jan 18 due the requirement to pack up the workshop to move, then we didn't - so unpacked it all. Then we found we needed to re-build part of my house as the builders had 'attached' the new steels to the old crumbling chimney with 4 x 2" bolts (!) without any chemical fixings, used dangerously below spec floor joists and generally left the house, mainly my son's bedroom, unsafe.

Oh yeah I could pull 1 of said bolts out with my fingers while undoing another. Sorry I'm ranting a little.

Now the house is nearly complete I have retuned to the multitude of projects in the workshop.

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True Tim - I'm sure there are better rants on here - I guess I have had time to process it all so my rants have faded out.

However - the positive is I am building models again. I have even cajoled my 12 year old into making a flat plate delta design for a bit of fun.

You must be nearing the maiden flight for your GTC?

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True Tim - I'm sure there are better rants on here - I guess I have had time to process it all so my rants have faded out.

However - the positive is I am building models again. I have even cajoled my 12 year old into making a flat plate delta design for a bit of fun.

You must be nearing the maiden flight for your GTC?

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True Tim - I'm sure there are better rants on here - I guess I have had time to process it all so my rants have faded out.

However - the positive is I am building models again. I have even cajoled my 12 year old into making a flat plate delta design for a bit of fun.

You must be nearing the maiden flight for your GTC?

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