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Richard's Grumpy Tigercub Build


rgarde
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Hereby the start of my GTC build log. Especially to let you know that I'm still participating.

Progress is very slow (slower than I want) due to other commitments & activities that I have at the moment.

I started by taking over and scaling up the drawing digitally. The drawing has been scaled up to get a wingspan of 1600mm (63" ). I'm also converting the drawing to be able to use metric sizes for the balsa and ply as imperial sizes are not available here.

The wing and horizontal stabilizer are ready on the drawing board. Also found time to upgrade my homemade CNC router and routing the wing ribs. I’m happy with the result. Next thing to do is to order some balsa and I can start building the wing!

Now busy with drawing the fuselage and wanting to make a start with the nacelles this week.

In contrary to my earlier starting points I will stick to the original design as much as possible. Main reason is that I do not want to make it too complicated because of the limited time available. Only changes will be round nacelles and maybe a more tigercat look a like turtledeck. In fact something just like Tim Ballinger's nice build!

The plane will be equipped with 2 os max 25fx engines.

Below some pictures of the first steps:

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Edited By rgarde on 30/01/2018 20:49:28

Edited By rgarde on 30/01/2018 20:49:53

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Hi Piers, thank you! The CNC router is one of my old projects of years ago. Worked a lot with it then and now back in service again. It worked with prehistoric software under DOS. Now upgraded the software so i can draw and route on the same PC. Also upgraded the stepper drives to have more torque and thus a bit higher feetrate.

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Hi Richard,

Nice cnc dude. I also made my own cnc machine a few years back and was really pleased with the result. OK it wasn't as fast as the commercial machines due to the small calibre lead screw but it worked - and it was a great project to do. I ended up selling it and then upgraded to a commercial machine which I have used a lot since.

Nice to see someone else CNC'ing there own GTC - my thread is under the 2018 MB. I also scaled mine to 63" span and drew a kit in CAD, then machined the whole lot. I use Solid Edge for CAD, then Curve Cut for nesting and MACH 3 for the machine.

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Hello,

Thank you all for the nice comments!

Still working on the fuselage drawing. I am considering to place the canopy, like the F7F, in front of the wing and therefore to extend the nose a bit. I have no experiences with changes of the basic airplane proportions. Therefore my question:

Do you think I can extend the nose by 10 to 12 cm?(from 23cm to 35cm) Are there any negative consequences by extending the nose? For example the flight behavior

What's your opinion?

Thanks in advance!

With kind regards,

Richard

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Love to see that CNC work. One day maybe!
​Would you say the advantages of the router are to speed things up (including programming and setting up) as well as better accuracy?
​Interesting to see what the opinions are about the extra length. It seems quite a lot to not make some difference.
Levanter

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Hi Levanter, I think accuracy will be the main advantage. And not to forget the fun of building one of course.smiley

I don't think it is faster then the conventional method. It will only speed up things when you can start from digital plans. Otherwise you need first to digitize the drawings. That's also a time consuming proces.

I see it more as another way instead of a better way!

Richard

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Hello Peter,

Thank you for your feedback. I indeed used your wing section. I am aware of the flat bottom surface and that the top surface is tappered.

On the forum I have seen that some people place the ribs with the flat site on the building board. So ribs are under an angle. I my opinion i think that it is easier to have both main spars under a right angle to the building board to measure and check when building. As it was very easy to add these tabs in my drawing I thought why not.

What is your opinion as designer of the TGC about extending the nose?

With kind regards,

Richard

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Richard,

A fellow CNC'er. I agree with you that most of your time is spent digitally drawing the plan before you can machine it. I guess the real advantages are accuracy of the kit you make and once the drawings and cutting files are made you can re-produce as many as you like. I made 2 GTC kits (shown in my GTC thread) - the second for a mate.

I really enjoy the whole process of drawing to machining and view it as another side of the hobby to enjoy.

I didn't put jig tabs on my ribs by the way and I have kept my nose as per the plan (although scaled to 68" span).

Best of luck with your build.

Rob

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  • 1 month later...

Hi Everyone,

I have made little progress until last week. Yes, I finally started with building!

The plans have changed slightly: I wasted much time with changing the drawing to a more tigercat look. I did not manage it good and think it is a bit too ambitious for me. Also because I have limited time for the hobby I have decided to stay with Peter’s original (but scaled up) plan. I really wanted to start building and not tampering around behind the pc.

And besides that, why change a design which has been proven good!

This week I started with building the right wing. Below you can see some photos of my progress. Comments and/or suggestions are always welcome!

With kind regards,

Richard

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Edited By rgarde on 02/04/2018 21:19:27

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  • 2 months later...

Hi All,

It is very quiet here on this part of the forum. So I thought it might be a good time to place a short update of my progress. I know that it is still not very much progress but every bit helps!

In the meanwhile the right wing half is ready. See pictures below:

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Although I already have several 25 fx engines I also had the opportunity to buy two os 25 fx engines at a second hand website. I could not resist them as I love these good little engines.

A part of the time was spent to bring the engines back in order. One engine was almost new and needed (except from a complete check up) no work. Unfortunately the second engine had a cilinder peeling problem. I had read about it on the internet but never had it myself. So I had to replace the cilinder liner and also the bearings of the second engine needed replacement. Now I have two nice engines ready and waiting for the Grumpy Tiger Cub.

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I have now started with setting up the ribs of the left wing half.

With kind regards,

Richard

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