PSS Wing Loading Help Requested

[Robert Armstrong 2]

Hoping for some advice.

I am new to PSS, though have been sloping for a couple of years (Wildthing, phase 6 and some foamies). I am hoping to get one of the Mark Kettle Vulcans (when i get to the top of his order stack) but also considering a conversion from and existing a rtf (I am not a skilled builder) as a second model. I imagine that getting the wing loading in a sensible range would seriously enhance my chances of success, which leads me to the question; What sort of wing loading will be sensible for a moderate wind model in the approx 50" wingspan size range? I suspect that the wing loading of my power models (Acro Wot, Wot4 etc would be too high for a sensible slope version)

Any help much appreciated.

[Andy Meade]

You'll probably get quite varied responses, but the Vulcan has a lot of wing no matter what scale you are at. Sensible or moderate wind I'd say you'd be shooting at around the 20-25 oz sq ft mark, though no doubt will be shot down in flames for that

Don't forget - you can always build it light and strong, then ballast up at a later point if the wind is gusty / painful / terrifying.

Did you have a specific RTF in mind? How about a Tony Nijhuis Vulcan built from a CNC plan pack? Might get the confidence up a bit for a plan build later.

 

Edited By Andy Meade on 05/05/2015 13:35:27

[Robert Armstrong 2]

Thanks for that Andy. Don't have a specific model in mind yet, though I lean towards a 50s to 60s jet, something like a Vampire or early US jet. Perhaps a Cambrian Panther? Maybe one of the Nijhuis range later!

[Andy Meade]

Oooh I love Panthers and Cougars. Definitely on the to-build list! Hopefully someone else will be along later (maybe tonight?) to either sanitize (or shoot down) my wing loading thoughts.

[Phil May]

One of my flying buddies has a foam Acro Wot with motor removed that he flies on the slopes.
Or build a cheap correx PSS Impala model...bags of fun

Edited By Phil May on 05/05/2015 15:11:09

[Phil May]

Oh, and you definitely want one of Marks Vulcans. 👍

[Phil Cooke]

I'd say you are in the right ball park Andy with 20-25 oz/sq foot - that would provide a nicely 'balanced' model - one that doesn't need a howling gale to fly in yet is loaded sufficiently to ensure forward penetration.

This is a well discussed question - really there is no 'right' figure on wing loading, just some agreed trends/characteristics that you should keep in mind if you wish to optimise the result - more important when designinng your own model I suppose, but it may also help you best choose a PSS conversion subject from the saturated electric and EDF ARTF market.

Remember, the best PSS models are those that not only look right, but they fly right too - by that I mean they cruise around at a representative, scale speed. The very, very best PSS models do this in a wide range of wind speeds meaning the model can be flown in a scale like manner as an everyday hack, not one reserved for rarely encountered, specific conditions.

As well as the model Robert you should also consider your typical day out gliding - do you fly from small hills or huge, coastal cliffs? How good is the lift generated for a given wind strength? This might dictate the sort of model you should go for more than anything else? As the power of the lift generated by your slope increases, so does your ability to increase wing loading and still succeed.

The bad news is of course - the only real answer to all this is to have a range of models with a range of loadings... one for every slope and every wind condition...and thats why we are always in trouble with the WaGs, the pursuit for the ultimate model really never ends does it!?!?

[Andy Meade]

There you go, the gaffer has spoken! Good points on the general flying abilities of your chosen design too - I think one of the best I've seen that can do everything is a JP to be honest - I've seen that flown in the gnat's proverbial to a 70mph screamer.

[Robert Armstrong 2]

Recently moved to Buxton, so Peak District slopes. Not very familiar with them yet, but I think they should mostly be good lift (part of the reason for choosing Buxton, of course ).

Did have a foam AcroWot 'converted' to slope (after the battery hatch came open in flight and the battery dropped out - subsequent impact bent the motor shaft). Flew well but wasn't very robust (probably due to the many cyano joins in the model after its 'conversion".

Have a 'Kettle Vulcan' on order.

Did ask on the Nijhuis Vulcan thread whether any PSS versions had been done. Don't seem to be so far and the various electric versions seem to be underpowered (at least for ROG from grass). Must work out the wing loading for that.

Impulse bought a book on the development of the Panther and Cougar series from Amazon earlier today. I believe Neil Armstrong flew one in his early career - would make an interesting choice of colour scheme.

[Phil Cooke]

Yeah the Cougar and Panther have both been well proven from the slope, good wing area is a great starting platform, Panther lends itself slightly better with the straighter wing IMO.

Paul Janssens does a plan for the Cougar - **LINK**

He has his own site - **LINK** where the plans can be purchased.

We also saw a couple of ARTF EDF conversions of the Panther a few years back, all foam, I think they were from the Overlander kit - maybe a bit lightweight and not robust for the slope without some glass coating but I recall they flew well!

**LINK**#

[Tim Mackey]

Minimum 50oz

[Phil Cooke]

Our A-10s will be approaching that believe it or not... and Matts Lightning was 44oz from memory. No bother on the Orme with a 35mph SWerly but I wouldn't like to fly them from Leek and Moorlands or Sheffield...

[Andy Meade]

Eeek. Don't suppose you have wing area info anywhere for the A10's? (sorry to de-rail thread a bit)

[Tim Mackey]

Yes I do believe it. Cant wait to see these A-10s - working gatling gun anyone ??

[Phil Cooke]

Andy, Ill email you a file, but from my working the wing area is 2100sq " or 14.6 sq ft - the plan shows it a little less than this but from memory we stretched the inner panels a bit...

You can do the math, but a 35lb model drops in at just over 38oz/sq foot - MONSTA!!!

[Matt Jones]

Simon and I have both flown models in the 40oz loading range,don't worry

[Robert Armstrong 2]

Ordered the JP plan and wood pack set from Traplett, Will try a Cambrian Panther when back in stock.

[Andy Meade]

That's awesome, well done Robert

Coming up the big rock in June?

[Mark Kettle 1]

Robert you'll like the JP, even though it is small it's a very nice and a fun flying model, mine flew at 37 oz.

By the way the EPP Vulcan has a ballast box and the oz per square foot in different wind speeds has been from :

• at 8 mph + = 9 1/2 oz a sq ft un-ballasted
• to 45 + mph with 32 oz of ballast making it 17 1/2 oz a sq ft ,

......however like Phil says at that weight it doesn't look like scale speed but it's fun.

Edited By Mark Kettle 1 on 08/05/2015 12:29:58

[Bill_B]

THIS may be of some use.

[Robert Armstrong 2]

I intend to get to the 'big rock' in June, though don't know if I will have anything to fly by then. If not will probably still come with camera.

Bill B, thanks for that.

[Tim Mackey]

Bring any model that will fly off the slope - pure glider / quiet electric assist etc - PSSA is not at all pretentious or snobby and doesnt have to be scale etc - we just love anything with wings ( fixed of course lol ).

Dont forget we are having a bbq as well so bring some nosh

[Peter Garsden]

Robert if you are moving to Buxton you just have to join Leek Moorland Model Glider Association. Phil is a member. It is only £10 to join and we have a slope for every wind direction. You can join online. I designed and maintain the website - **LINK** You can join online using Paypal.

In answer to your question. I have several PSSA models including a Vulcan not built from the Mark Kettle kit as it didn't exist 2 years ago when I joined but from a My Hobby Store plan. Mark's I think is better. I also have a JP, A power model converted Hawk, a Tornado (all the blogs are on this site) and a Paul Janssen Alpha Jet.

I would say that I suspect the Hawk and the Tornado are not really suited for the slopes of the Peak District because of their wing loading and only really fly well on the Orme whereas the others can fly as long as the lift is reasonable, but the best slope for PSSA and it is brilliant is Bosley Cloud, where I have effectively flown all of them except the Tornado because it is so new.The other slopes are OK for sports models but PSS struggles.

[Robert Armstrong 2]

Peter, I am already at Buxton and have joined the LMMGA. Have flown at the Gate and Elkestone only so far. Hope to meet you sometime.

[Andy Meade]

I'm definitely coming up to fly Bosley Cloud sometime this year. I remember in the dim and distant past (nearly 30 years ago) when I started to get into r/c aircraft, my tutor at the time took our family up there to have a look at what slope soaring was about. It was grey. It was windy. It was fairly wet too! But half a dozen heroes were on the edge, tearing up the sky with some flying wing design or other.

It frightened the bejasus out of me! Anyway, a bit off-topic, but I must get back there at some point to complete my pilgrimage where my first sloping seeds were sown.

Edited By Andy Meade on 11/05/2015 08:45:11