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The Norwegian Gnat Squad

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Lucas Hofman07/01/2020 13:46:53
664 forum posts
375 photos

After doing a club build of 7 Microaces Scrappee's last autumn we have decided to prepare the summer season with building a handfull of Gnat's together.

Most work will be done during the Wednesday Club night, so progress will not be very quick. However, that does not matter since there usually is snow on the ground until May.

3 member (your scribe included) have signed up, and to make things easy we have ordered kits from Tony Nyhuis.

So let's Go!

Lucas

Lucas Hofman07/01/2020 13:53:11
664 forum posts
375 photos

The kits have arrived in the London office:

kits arrived.jpg

Now I wait for a colleage to bring them to Norway.

The FMS units are supposed to be send from China in the last week of January. So by the end of Feb all should be here.

Lucas

Tim Ballinger07/01/2020 15:46:45
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778 forum posts
283 photos

Good luck Lucas, with only around 20-23 pieces of balsa to glue together that’s one club night. Another to cover it and away you go !!😈

Tim

Lucas Hofman09/01/2020 12:39:22
664 forum posts
375 photos

Not at our rate of chatting versus glueing....

Lucas.

Lucas Hofman09/01/2020 12:44:42
664 forum posts
375 photos

Morten (on of the other building) found laminating pouches. After being run trough the laminating machine (without paper in between) it ended up like this:

folien morten.jpg

0.2 mm. Would that be OK?

Lucas

Lucas Hofman09/01/2020 12:55:27
664 forum posts
375 photos

We purchased (on Banggood) DHV56MG servo's. Digital, 5.6 gr, 1.2 kgcm, 0.10 sec. And a pleasant 6GBP price tag.

I have never used these before. They look good whn testing on on the bench after arrival: zero slack on the shaft, little play in the gear, nearly soundless and (as far as one can judge that) they seem to center consistently.

servotest.jpg

And the first one survived 500 cycles.

Lucas

Lucas Hofman18/03/2020 13:26:36
664 forum posts
375 photos

At last the kits arrived in Norway: (just before the borders where closed...)

img_6733.jpg

Lucas Hofman18/03/2020 13:30:39
664 forum posts
375 photos

To avoid local virus spreading our national assosiation has strongly advised all clubs to cancel any activities, so this will not be a club evening build. However, Morten has started. As a graphical designer his planes always look good:

20200318mortencolours.jpg

And his first steps. He is using a building board of 5 cm blue foam, which is both stiff, light and take pins very well:

20200318mortenfirststeps.jpg

Cheers

Lucas

Lucas Hofman21/03/2020 21:03:13
664 forum posts
375 photos

Some creativity in creating the thrust tube: Morten, one of the builders experienced that his tube material was to stiff to bend to the required diameter. He came up with the following solution:

mortenthrusttubebaking.jpg

150 degrees centigrade for 10 minutes. The result is this:

mortenbakedthrusttube.jpg

I wonder whether the ridges will lead to loss of thrust.

Regards,

Lucas

Lucas Hofman21/03/2020 21:05:18
664 forum posts
375 photos

Some more progress:

mortenfuse.jpg

Mounting the thrust tube:

mortenfantube.jpg

And the air intakes:

mortenairintakes.jpg

Morten is still the only one building. I hope to start real soon now...

Lucas

Tim Ballinger22/03/2020 09:35:12
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778 forum posts
283 photos

Lucas, Glad you are getting going. Guarantee you will be exhilarated when you get the gnat in the air; I know I was.

Little concerned about the thrust tube. If it is that stiff how much extra does it weigh? Like you I would also be concerned about the ridges disturbing the airflow . You will know from reading the other build logs of the delicate thrust - mass balance with these mini jets. 1 oz is huge !

Seeing all the angst others were having getting their models away from the hand launch ( admittedly mainly the JP) I fine tuned my thrust by incrementally making the ‘Cheat’ intake larger until I achieved the spec thrust level.

Sure you know all this but I thought it worth emphasising.

Tim

Edited By Tim Ballinger on 22/03/2020 09:36:03

Lucas Hofman27/03/2020 20:45:57
664 forum posts
375 photos

Started at last. Covering the building board with a clean piece of film is always a milestone:

img_6764.jpg

I show my method of glueing wing sheeting together (this should after all provide some support for new builders). For most glue joints I use PVA (white glue), which remains elastic, but here aliphatic glue is used, because it sands better.

Step 1: fit the pieces together, sand a straight and perpendicular edge to each. Degrease and put a peace of tape over the joint.

img_6765.jpg

Fold open and apply glue

img_6766.jpg

Close the joint (tape down on the board). Weight the parts so they lay flat. Glue will oose out.

img_6767.jpg

and scrape away superfluous glue

img_6769.jpg

For thin sheets (i.e. when covering a wing) I tape the top side of the joint too. Here it is not needed.

Inspection by the master of the house

img_6772.jpg

Cheers, Lucas

Lucas Hofman28/03/2020 20:34:23
664 forum posts
375 photos

Profiling the wings tonight. I did not manage to mark the edges as described on the drawings. However, by putting the wing flat on the board beside a 1.5mm balsa flake one gets perfect lines straigh away:

img_6773.jpg

Using a plane was a little uncontrolled (the plane buried itself in the balsa). I bevelled the wings with a big sanding block with 120 paper.

Lucas

ps. anybody reading this, or is everyone already finished with his mini jet?

Geoff Gardiner28/03/2020 21:38:20
avatar
534 forum posts
912 photos

Hi Lucas.

I'm watching.

Dickw28/03/2020 23:21:37
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665 forum posts
93 photos

I'm watching as well.

Dick

Tim Ballinger29/03/2020 09:38:59
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778 forum posts
283 photos

Hi Lucas,

Glad to see you have started. You probably noted from earlier build logs that some of us found making the wing join much easier as you do the final assembly into the fuselage. It is a bit of a fiddle with the completed wing and you stand a chance of breaking balsa as you manoeuvre them in. Others seem to manage ok but I decided to join in situ after making sure the brace was a perfect fit of course.

Tim

Lucas Hofman29/03/2020 12:30:46
664 forum posts
375 photos

Thanks Tim, I will do that.

I did not find many build blogs. Are they in other places that in the Mass Build area?

Lucas

Tim Ballinger29/03/2020 13:02:00
avatar
778 forum posts
283 photos

Lucas,

Several of us started off before the mass build evolved and we all just chipped in snippets to Tony’s original build log which actually cover all the mini jets but I suppose mainly the JP and the Gnat. This the original thread......

All Forum Topics > Tony Nijhuis plan builders > New EDF Mini Jets- Jet Provost & Folland Gnat

Tim

Lucas Hofman06/04/2020 08:55:24
664 forum posts
375 photos

Started with the fuselage. Rectangular sanding blocks ensure formers being glued on 90 degress to the sides.

img_6786.jpg

I did a trial run of the fan at this stage. Smooth running but only 30A with a full battery. Is that enough or do I need to get fresh batteries?

Cheers, Lucas

Tim Ballinger06/04/2020 09:09:08
avatar
778 forum posts
283 photos

Lucas,

sounds as though it could be a bit marginal to me. My static tests gave me 42A , 600g thrust at 49000 rpm ( the rpm figures in the static test I showed in the build blog were out by a factor of two as I confused poles and pole pairs when calibrating the rpm sensor). Those figures were with a newly charged 40C battery. I’ve seen others measuring 38A but not sure of the battery status.

Tim

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