Swift 3.19m - Oh nooo, another project on the work bench ...

[chiloschista]

... and this time it's even not mine

 

Hi ensemble,

 

after a long wait I received today a big parcel: 3.19m Swift from Topp-Rippin.

This is for my son, so I learn to infect young people with RC virus!

Doing it means putting aside my own projects, mhmm.

Should find a solution:

anyone knowing a rich (young, beautiful, devoted to RC) widow, so I could invest all my time in RC planes development and building?

 

Will post progresses, when there will be some.

Best regards,

Ric

 

[Skip]

I've always had a bit if a man-crush on Swifts. Gorgeous planes.

Is it a nice kit?

[chiloschista]

Hi Clayt,

depends on what you expect from a kit.

I like Topp Rippin planes because they are strong and affordable. I'm just a little disappointed with the fuselage. I expected a strong heavy one and got a nice light one, better devoted to flat land.

On another side I'm not convinced about their airfoils choice.

I asked last year for a plane to my desires, but was not able to have an offer. They make airfoils changes etc, but are still working in DOS!

For this one I just asked for wings with flaps and without spoilers and got. Right now I would have asked for a couple more fiberglass layers in the fuselage.

I'm tempted to clone it and make one to my specs ...

Ric

[Weysoar]

I have a Topp-Rippin 5m DG, just started to build it, the fuse is light, as you suggest. I'm using a mix of reinforcement, carbon (200gsm) around the cockpit and boom, where I can reach and some carbon tubes inside the boom.  I am going to use some polyurethane non expanding glue, should be fine.  I will also laminate some airex or similar with carbon either side to use as stiffeners/formers inside the cockpit.

 

I have already cut the surfaces out and varnished the wings and apart from a sand will cover with Star-vinyl graphics material.  I also have the wing tip extensions to take it out to nearly 6m, they can wait till last.  Airbrakes are already fitted along with the wiring.  I have carboned the servo bays.

 

The kits are the Pat Teakle kits for the 21st century.

[chiloschista]

Sorry, I can't understand: is it a Topp-Rippin or Pat Teakle kit?

 

About fuselage, I really *hate* having to rework it. It should come out of the mould finished.

I have now to discuss with my son if he wants it reinforced a little bit. I could put some Kevlar in the nose (carbon is not the right choice, that's for stiffenes, not shock absorption, kayak teaches).

Or do a mould and build a few with Kevlar and maybe in flax (and wings as I would them like).

Comparision from my Foka4 (2.2m) flax fuselage and that one is 580g vs. 800g!

 

Considering that this plane should be at least 5kg, better 6kg to fly well I'm worried about the amount of ballast to put in.

The total kit weight is about 3kg. The wings are exactly the same weight at 915g each.

 

I also considered buying fuselages from Gewalt, but they have crazy high shipping rates (€150.-)

I can't understand how Topp Rippin can ship for such low rates (€21.-).

It's time to put the router under stress, after a CAD session, and mill a plug myself?

 

Ric

[Woodstock]

..............

[TonyRH]

Hi

A Pat Teakle Vega had its maiden flight kver Dorset slopes this week.

What a fabulous bird she is.

A word of warning though. My ailerons in common to many are single taped onto the wing BUT it didn't hold. So there is now a 4" deep hole down there somewhere.

Pre flight checks didn't pick this up.

I've been told by my elders that it should have been Diamond taped top AND bottom onto the wing.

I'll follow thtough on that advice.

A further point was difficulty in establishing a c of g. This example had no repairs to the fuz: so no extra rear weight to compensate. The c of g is to ne as the Teakle original drawing, that is the , leading edge of the wing spar.

In my Vega the spar is a 1/2" dia 575mm long duralumin rod, now needing replacement!

Cf rod here we go but from where? Any ideas folks?

How magic is thqt moment when we finally face the slope, model being buffetted by the winds 12knts for my maiden And lift off! I HARDLY NEEDED TO THROW IT FORWARD.

Tony

[Woodstock]

Erm, what caused this 4" hole?

[evad]

Erm, what caused this 4" hole?

I'm guessing here but .........plane meeting ground !!  hence the need for a new wing joiner 

 

 

dave 

[Bear]

Hi Ric,

 

How are you getting on with the Swift, really tempted by their MU 28 but your initial thoughts on the Swift has made me hesitate, any further thoughts?

 

Roger

[chiloschista]

Hi Roger,

 

I'm actually stuck with the third, speed Foka4 and CNC cutting plugin issues.

I discussed with my son and decided *his* Swift needs some layers of fiberglass and Kevlar to become slope like.

In general it is well done, but the builder owner (Sabine) told me they build like that because several people build it to fly with turbine on flat fields, so they have to be light.

 

I was tempted by the MU28 also, I like that shape. Or maybe a fuselage only and build myself the wings.

But actually I'm focused on my own designs and really would like to come out with the Red* for the summer.

 

Ric

[Bear]

Thanks Ric,

 

I think I will go for it and reinforce the fuselage as you have done,  I guess it makes sense for the manufacturer to build light, it is much easier to add strength and weight than take it off. I really wanted the 3.5m Gewalt one but like you found the shipping cost is just silly!

 

I like to try and build at least one model each winter but have left it a bit late, I hope the MU28 will be a quick build.

 

Like your Fokka 4, hope to see it in the flesh soon

 

Roger

[chiloschista]

Thank you, Roger, very kind!

 

Mhmm, don't take it for granted that build a Topp Rippin model is a quick one.

Usually you have to find several solutions about how to mount elevator, wing joiner etc.

On their Salto I had to invent a way to build the elevator, starting from the right angle, not to tell dihedral. No mention about CG.

Now they improved a little bit on that side, but in what I know they remain models for the builder.

They are cheap for a reason or, from another perspective, you pay the rest with your time and extra accessories.

 

Why not ask them to build it reinforced from factory, they usually do that service for small extra amounts, or maybe the Mu28 is still build in the old school way.

 

Well we are starting to plan the summer travel. Probably UK, but still not clear where. Last year we missed the Bwlch and the Skirrid.

I have to say that I was tempted by Norway, but it is sooo far from here and with a caravan behind ...

Maybe one time or another we will be able to plan a 5 weeks trip ...

 

Ric

[chiloschista]

Hello,

little by little I'm coming back to my builds, ouff ...

The Swift got a layer of 163g/m² fiberglass inside the fuselage.

Horizontal geometry set and wing joiner tube glued in place.

 

Now it's time to cut ailerons and flaps. The factory lines seems to me way off any aerodynamics logic. They simply draw a line 50mm wide along all the span.

So flaps are definitely too much small and ailerons at tip are way to big. Yes, it is more scale like that, but who cares, I'm interested in flying behavior. I have seen that there are few building like that and am wondering if they are simply lazy or if there is a reason I'm missing.

Anyway I'm going toward a linear 25% of the chord control surface, instead the usual 22.5% seen it's an aerobatic plane, unless someone will give me a *good* reason to do otherwise.

The more I think about it and the more I'm convinced this will avoid strange, bad behaviors near tip at high ailerons throws.

Ric

[Phil.Taylor]

Ailerons should be constant width - so bigger % chord towards the tips - full-size is like that - MDM1 Fox is too  - probably because:

- more aileron effect towards the tips where its got most leverage - especially for those crazy flicks/spins - that "strange bad behaviour" is there for a good reason

but its your plane - and of course the full-size doesn't have flaps

Phil.

http://commons.wikimedia.org/wiki/File:Swift_s-1_glider_g-izii_aerobatics_at_kemble_arp.jpg

Edited June 14, 2015 by Phil.Taylor

[chiloschista]

That's exactly what I meant, Phil.

Thanks for your input!

I'm still not convinced that's a good solution on a flying model, flying at really lower speed and way lower Reynolds numbers than a real scale.

I verified several sources also. Quabeck teaches: 22.5%. On the planes I have, designed by a great designer which J. Hammond is: 25%.

I asked T. Platon long time ago about one of his aerobatics airfoil: 30%.

So 41.6% seems definitely too much to me.

They could even be less effective, creating bigger vortices and extra drag and bad torsion effects at wing tip (aileron reversal in the worst case).

Am wondering also what happens if the air flow is forced to work in a different manner along the wingspan.

Should build two with both options to test, maybe next life ...

Ric

[Phil.Taylor]

All the scale model Swifts & Foxes I've seen have flown just fine - lots of videos on the web -  aerobatics mild to wild

Constant width ailerons also work great on the Habicht - full size and model

Maybe - stop thinking efficient soaring glider - start thinking effective aerobatics glider?

food for thought - the elevator is 40-50% of the tailplane chord

Phil.

Edited June 14, 2015 by Phil.Taylor

[chiloschista]

Hello,

 

time to put hands on it, if we want flying it in UK!

So I am about on ailerons and flaps cutting, but have a doubt: hinge them on top or at bottom?

I usually hinge things on top, except the Trisel (hinged on bottom side), but am never satisfied about flaps behaviour in crow position. The main reason to do that is the way I build wings, to have the top surface the better I can at cost of extreme crow position, but on the Foka4 that's ok.

Hinge them on bottom side (am I putting some fuel on fire again about scale/no scale etc debates =:D) and have the amount I want, or hinge them on top and limit flaps down at about 45°? The second one is the more usual, but that's not a good reason.

All the RCRCM planes we have are hinged at bottom side. In this case obviously the gap at top will be closed with the Graupner special tape.

I guess I spend more time thinking how to do, than really building (but at the end my planes flies well =:P).

Btw there is a great difference between the Sunbird and the VectorIII, with flaps at 90° ant the Foka4 with flaps at about 45°.

With the Sunbird in particular I land downhill at incredibly slow speed, while the Foka4 will not brake that much.

Thanks for inputs!

Ric

[Tilman Baumann]

Bottom hinged can have another benefit.

The gap can act as a turbulator and increase pressure on the rudder surface.

[chiloschista]

Bottom hinged can have another benefit.

The gap can act as a turbulator and increase pressure on the rudder surface.

Could be, Tilmann.

But the job of a turbulator is to force transition from laminar to turbulent boundary layer and avoid early flow separation.

At 75% of the chord the boundary layer is turbulent already, even on laminar airfoils.

I know there are people positioning zigzag tapes just before control surfaces, but would like to understand that (ehm ... scientifically) and have proofs of real benefits (ehm ... scientificals).

Am not sure about those tapes, because a turbulator has to have a particular thickness, well more than a tape.

If my calculations are right the boundary layer on tip side of the Swift at 10m/sec (about landing speed) should be around 5mm!

So near the hinge probably more, with ailerons up, well ... a mess.

And max roughness allowed, for a laminar airfoil is around 0.14mm.

Yeah, still a lot to learn ...

Ric