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Nutball

Foam board quick build

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Nigel R07/01/2019 17:04:47
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2849 forum posts
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Excellent stuff Dave.

It is obvious from the video just how smooth the centre section is on the Nutball.

I wonder if the large dihedral tips increase the size of the tip vortices?

Your flat acorn shape (I guess that is the inverse Zimmerman) seems more akin to a conventional delta performance.

On the stability front, with the inverse Zimmerman Nutball with dihedral, I guess the acorn shape puts more of the tip area in cleaner airflow? I found my standard one already very stable in high alpha.

These things are a proper little nugget of gold.

Nigel R09/01/2019 14:00:38
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Well, that was fun. Got 5 more flights in just now. Mostly playing with the wind. It's very stable, despite the breeze, and hovering is no drama whatsoever. Land at my feet, hop over the fence, go backwards, go sideways, go round a bush, climb and glide (not so good), inverted - tricky, it prefers to go back upright, loops are very, very tight, and you can do a kind of flat spin thing as long as you don't mind it pointing up at 45deg.

Heaps of fun, ridiculously good value for money, and absurdly short build time.

Lima Hotel Foxtrot09/01/2019 17:10:24
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336 forum posts

I've built several of the Flitetest models now, and they all fly brilliantly. The value for £ is excellent when you consider the cost of materials, printing off the free(!) plan and build videos online.

I recently modified an FT Flyer with ailerons, and it now gets flown more than any of my other planes. Excellent, adaptable models all.

Nigel R09/01/2019 18:19:34
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2849 forum posts
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"cost of materials"

The whole thing was under £40, including all radio & motive electrics. Proper pocket money modelling. I'll probably decorate it with a permanent marker, coloured in with some kids crayons. Or maybe my offspring will decorate it!

In many senses, we've never had it this good.

I reckon I'd have to budget a minimum of five times that for a regular 20 or 40 size balsa build, and a normal wood build is more like 100 hours for me (yes, I'm slow). Not the 3 hours this took.

Don Fry09/01/2019 20:39:34
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3616 forum posts
42 photos

I've got a 1700 kv, 3s motor spare. On a 7*4 it will produce about 450 grams of thrust. I used to run it in a racing sledge until it hit one wall too many. Would Nigel's Nutball be a fine destination for it?

SWMBO likes her holidays, and small machines to take with me are always welcome.

Nigel R09/01/2019 20:52:53
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2849 forum posts
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Sounds just about perfect Don.

You're welcome to measurements from mine - it's a straightforward scale up from the original design.
Don Fry09/01/2019 21:04:02
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3616 forum posts
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Great, what's the scales ratio, and I will print a plan.

For scales read scale.

Edited By Don Fry on 09/01/2019 21:04:42

Nigel R09/01/2019 22:21:46
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https://www.rcgroups.com/forums/showthread.php?836389-The-NutBall-best-damn-RET-foamy-yet
Nigel R09/01/2019 22:23:14
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2849 forum posts
469 photos
Don there is a diagram in the first post on that massive thread. That has all the measurements for a 17" version. Mine is 23" but all the same shapes and angles and whatnot.
Nigel R09/01/2019 22:27:16
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2849 forum posts
469 photos
I deviated a bit by making a U shaped spine underneath. The spine is as long as the diameter of the main disc. It sticks out by about 4". This made balancing very easy. Motor is hung on the end of the spine as photos make apparent.

Edited By Nigel R on 09/01/2019 22:28:32

Don Fry10/01/2019 06:25:11
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3616 forum posts
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Thank you Nigel.

Former Member10/01/2019 08:54:35
1322 forum posts

[This posting has been removed]

Nigel R10/01/2019 08:58:23
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2849 forum posts
469 photos

No problem Don.

Piers, not sure how I missed your links, the Little Bird is great.

The Capricorn looks great.

On a similar note, my bucket list contains Laddie Mikulasko's excellent looking Arrow:

https://outerzone.co.uk/plan_details.asp?ID=6504

but reduced size in foamboard or depron. It is a simplified version of his Northstar:

https://outerzone.co.uk/plan_details.asp?ID=10325

which was reduced to make the Polaris - starting another very busy RCG thread - which seems to have been cloned by Hobbyking as the Artic Cat.

Not yet though. Going to do a standard prop-at-front delta type before that, as mentioned I like the look of the Dekan's Simple Delta which bears a passing resemblance to the Drakken.

Nigel R10/01/2019 09:05:19
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2849 forum posts
469 photos

Dave, draggy, yes, the glide is not fabulous. Although mine will still stay aloft for 8 minutes on a battery that will give 10 minutes on a clean (ish) conventional layout model. So perhaps not all bad.

Nigel R10/01/2019 09:07:30
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2849 forum posts
469 photos

Don, also worth noting, the downthrust angle is very important. I had mine way out on first flight and full throttle produced nothing but tight loops. Easily fixed with a few strategic washers.

Former Member10/01/2019 09:11:46
1322 forum posts

[This posting has been removed]

Piers Bowlan10/01/2019 14:32:32
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1769 forum posts
42 photos

.

Edited By Piers Bowlan on 10/01/2019 14:51:11

Piers Bowlan10/01/2019 14:37:25
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1769 forum posts
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'Not a bad glide' . It could depend on what you are talking about. These low aspect ratio / low wing loading 'flying wings' can fly at a high A of A without stalling, but without power the glide angle is steep, so not a good glide compared with conventional aircraft. However, their sink rate is low, due to the low wing loading, so from that perspective you could say they glide well. Especially true, as they are so easy to control and stable in this region of their flight envelope. They also have a very good speed range, the Arap S2 stalled at 23mph but had a top speed of 97mpg, all on 37hp; remarkable! There have been other similar low aspect ratio aircraft like the Barnaby Wainfan FMX-4 Facetmobile and the new two seat Verhees Delta. Fascinating stuff!

Nigel, thanks to the Outerzone link to Laddie Mikulasko's Arrow. I built a North Star some years ago but lost the use of the lake before I finished it sadly. I only binned the wing six months ago - I could have built an Arrow from it. Dam!

 

Edited By Piers Bowlan on 10/01/2019 14:50:14

Don Fry10/01/2019 15:25:26
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3616 forum posts
42 photos

Thank you lads, I will do one. Initial fag packet calculations done.

Piers, I built, about 20 years ago, a free plan from Radio control Scale Aircraft? It was a scalish thing of something with the nickname Flying Doughnut . Interwar French design I think. It flew ok. It had no stall to speak of, but eventually mushed without much control. A circular wing design. Would update well to electric and depron. Pretty thing.

Nigel R10/01/2019 15:37:17
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2849 forum posts
469 photos

The two seater Verhees is a lovely piece of work. Dream project, when the kids have moved.

I think deltas have a lot going for them in the land of light aviation, but I am not a lightplane owner, so, pinch of salt.

"It could depend on what you are talking about."

Well, my comment was specifically relating to glide time.

During a glide it is of course easily controllable. It is simply that the glide slope is quite steep.

Of course this steep glide can be of huge benefit if you operate from small fields. Not specifically for this size foamie, but particularly in bigger heavier models.

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