Jump to content

Nutball


Nigel R
 Share

Recommended Posts

Advert


Today was calm. Ideal for a test flight.

Pleased to report the rumours are true. It flies superbly.

My six year old did circuits with it for three flights. I chucked it around on a fourth. Great fun. Hovers brilliantly and turns as tight as you like.

I did some laps around a big bramble bush and nearly caught it by hand when landing.

Great stuff.

Took three hours to make it. About a hour of foam and the rest was motor mount and gear install

Link to comment
Share on other sites

It was one of your postings on increasing the strength of Depron that first led me to the design, dave m.

Dave h useful link thank you.

Next foamboard I'm thinking of doing a dekan delta which is a halfway between pizza box and regular delta.

Edited By Nigel R on 05/01/2019 18:44:33

Link to comment
Share on other sites

This is an old video from nine years ago of Capricorn, the flying 'W'. It has been on my build list ever since (I know, I know, - another one!). These low aspect ratio aircraft do seem to fly well, I suppose very light weight and loads of power has it's benefits.

There have been several full sized examples of these low aspect ratio aircraft like the Arup S2 and S3, the Vought V173 flying flapjack, Eshelman Flying Flounder and more recently Milt Hatfields 'Little Bird'.

Edited By Piers Bowlan on 06/01/2019 05:20:21

Link to comment
Share on other sites

You can buy Flitetest waterproof paper covered foamboard in the UK for £2.50 per sheet. It's an excellent material for building planes like the Nutball - and anything else for that matter. Here's my Hots 40 coming on nicely. A plane like this took me only a few hours to make.pre finish.jpg

Link to comment
Share on other sites

Dave M - nice thread. Some good links and "shape" design layouts in there!

The stall characteristics do seem to be the thing that sets the very low aspect ratio craft apart from conventional. I guess it is a side effect of the amount of the wing which operates in the tip vortices.

Link to comment
Share on other sites

On a side note, if a square has an aspect ratio of 1:1, then a circular wing like this has an effective aspect ratio of 1.3:1.

A little higher than my recent flying carpet effort, which had as aspect ratio of 0.45:1!

The nutball loops much better than the carpet. Other than that it seems somewhat similar in its close-to or post- stall behaviour.

It's also worth noting that the U-channel spine that I used on the underside of this nutball worked very well - I can stash the lipo just in front of the wing in the trough that is formed. And sticking on the motor mount was very easy. Provides something handy to grab when launching, too. I realise this might be a bit of a schoolboy observation to all the foamboard pros out there.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

"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.

Link to comment
Share on other sites

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.

Link to comment
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.
Note: Your post will require moderator approval before it will be visible.

Guest
Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

 Share

×
×
  • Create New...