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Why not use inexpensive sprung oleo legs? I have a pair intended for my Percival Mew Gull from HobbyKing but I haven't tried them in anger yet.

I have the standard undercarriage as Peter designed and fly off a hard runway which I guess is as firm as ice. I find landing is (usually) fairly bounce-free and I am far from an expert pilot (especially landing).

Geoff

 

Edited By Geoff Sleath on 05/01/2017 10:46:45

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I looked at them Geoff, but they look like too big for the Ballerina. Do you know if

- they absorb, or is it only a spring in a tube?

- the spring can be adjusted (or changed out)?

The wheels are quite far ahead of the CG, which means any vertical speed left at touch-down rotates the plane and it starts flying again. It can only do that when the wing is not stalled off-course, so maybe I should come in more nose-up (and slower). With an F3A plane one often touches tail wheel first.

I will bend up a thinner undercarriage to start. 4mm for 1800 gr. is probably needlessly stiff.

Lucas

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Posted by Lucas Hofman on 05/01/2017 08:48:23:

About 50 flight done with my Ballerina now. I would like to have much suspension (vertical) in the undercarriage, since it is very difficult not to bounce when landing on ice. I ordered "very soft" wheels from HK, but when they came they were the same that already are fitted

The legs are nearly vertical, and while the construction has a nice springy action in the for-aft direction due to the torsion wire, it is stiff as concrete in the up/down direction.

Any ideas on how to improve this?

Lucas

A simple solution perhaps, Lucas, is to splay the legs outwards slightly so there is more give in them rather like this Victor Airtourer here. I know this has a trike landing gear but you get the idea. Shock absorbers sound rather over engineered for this elegantly simple model. The outwardly splayed legs (as well as being raked forward) will have a little more give even though they are not damped.

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As I said. mine doesn't often bounce. I tend to let it find it own glide path and just fly in with the merest touch of flare.

To be honest I rarely land perfectly but the pecentage is much higher with Ballerina, . I don't try for three pointers, just happy for a smooth landing

In fact Ballerina is a lovely model for repeated touch and goes.

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A simple solution perhaps, Lucas, is to splay the legs outwards slightly so there is more give in them rather like this Victor Airtourer here. I know this has a trike landing gear but you get the idea. Shock absorbers sound rather over engineered for this elegantly simple model. The outwardly splayed legs (as well as being raked forward) will have a little more give even though they are not damped.

Hi Lucas,

I'll second Piers totally with his proposal. The static angle will give a 'start' for the vertical bending.

But then - as you wrote - I also think that 4mm might be a bit too much as your Lady is the lightest one of the conventional builds. I suggest having a try with 3mm wire, possibly also splayed out a bit as Piers suggests.

I used 3mm wire on my Bella, but I sandwiched a 2mm carbon rod to its rear held in place by 3 pieces - top, center & bottom - of thermo-retracting insulation. It nicely hides into the back binder that you are using too.

Cheers

Chris

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On a purely technical note spring rates and damping are actually inversely related.

Any plane has a degree of aerodynamic damping so the softer the springing the more relatively effective it becomes in controlling the rebound.

Most models are extremely strong so the undercarriage springing tends to be set up accordingly. The resultant short U/C travel means the limited aerodynamic damping has little effect so virtually all the landing input energy is returned.

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  • 1 month later...
  • 2 weeks later...
  • 3 months later...

A bit late, but I'm a slow builder and I like to fiddle with the plan -and savour every moment. That's my excuse.

ballerina 1.jpg

Same assagi pilot as Peter used so must be experienced... (I wish he still made them)

ballerina 2.jpg

Split flaps too.

ballerina 3.jpg

The field doesn't really slope like that, in fact it is flat.

Does it fly well? Oh yes very well indeed. 640W and 4lb 6oz and it can really buzz. The flaps are a novelty, not needed but they do add fun and allow a very slow landing.

It can be very gentle or quite energetic if you open the taps. I think I need to move the battery back a bit though as it is difficult to get it to spin.

Really enjoying it. Another good one Peter!

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Hi Mowerman, the vinyl decal is 'Craft Dancer 004 and obtained off ebay seller '2015faile' (note there is no 'd'!)

They run an ebay shop called Saxon Digital Servicesbased in Norwich, the cost was very reasonable at 99p for 2 and 99p postage, and available in different colours. These were 'small' size 10cm but other sizes were available. They were bought early February so don't know if they are still selling.

Very pleased with the quality and they are sticking very well

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Congratulations with your completed Ballerina.It has been my winter favourite. The problems with entering a spin are due to the rounded leading edge of the wing airfoil combined with a low wing loading. I get it to spin most reliably by keeping about 25% throttle, flying nose high a gently have more and more elevator. When the plane stalls (but not before) full rudder. I do not remember of aileron appliation is necessary.

I think the decal is the same as mine. Can be downloaded for free somewhere. If you send me a pm I can send a pdf.

Lucas

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I didn't bother with a decal. I googled "ballerina silhouette" and found what I wanted. I then sized it and printed it, then stuck it to a piece of covering with a glue stick, and cut round it with a scalpel. I used the same method for the letters. They are then ironed on. It saves trying to find stickers or vinyl the same colour as the covering.

ballerina 002.jpg

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