H101 Salto wing section

[Peter Balcombe]

Looking at designing a new built-up wing to go on a PT ¼ scale Salto.

In common with most scale model fuselages, the Salto has wing root stubs with the original airfoil section, which is thought to be a Ritz 1 type as far as Pat can recall.
Pat thinks that the model would fly better with a Ritz 3 section.

Has anyone a better (airfoil) suggestion for this aerobatic model?
Peter

[Keith]

Have you checked with Cliff Evan's as he was going to do built up wings for Pat's models.

Keith

[B Sharp]

Peter. The first thing you should check is the angle of incidence of both roof stubs on the fuselage. Many years ago I picked up an unstarted kit for the PT Salto. I built it as per plan/instructions (bear in mind I had built several PT kits before) and very nice it looked too. When I flew it however it had a serious right hand turn which could only be held with full aileron trim. I checked the wings for warps but they looked true. I eventually checked the angles of incidence and found there was a 2 degree difference left to right. This was traced back to the wing stubs themselves. I eventually managed to bodge up a fix but this is the only fuselage where I had this problem.
Brian.

[Peter Balcombe]

Have you checked with Cliff Evan's as he was going to do built up wings for Pat's models.

Keith

I think I know who was getting the job

From what you say Brian, it would be worth Cliff giving the new mould doner fuselage a good coat of looking at before potentially perpetuating any possible offset.

[terry white]

Hi Peter,
Ask 100 modelers which wing section to use on any particular model and you are likely to get 200 answers back, but then you already know this.The H101 Salto is an enigma of an aircraft at full size. It was designed by a lady glider pilot who flew the Libel as a past time. She required more in the way of aerobatics and so taking the Libel as a starting point designed the H101 Salto. I believe only a handful were made (about 15 as I recall) The models are enjoying a somewhat of a resurgence on the scale scene at the moment. Due to it sleek /slender looks and unmistakable presence in the air. It is modeled by a number of quality manufacturers from the continent at present, Valenta, Bouldis, to name just two. Mind you it will set one back about £1000 per model with a 4 months waiting time.The Salto at 1/4 scale is defiantly NOT an entry into scale modelling as it has a number of vices which is difficult to model out,it is part of its DNA, but when conquered is the reason why it is loved so much by its owners.I have owned 3 of Pats and two of Valentas in my modelling career and I would say the excitement of flying them is only equaled by flying the 'Fox',a more modern aerobatic aircraft. One does not buy a Salto to stooge about looking for thermals in the normal glider sort of way but to throw it about and thrash the air to give the pilot the fix that he bought it for. The pros and cons of the Salto as a model are quite a number. The long slender wings with very little cord at the tip just loves to down wind tip stall if one does not keep the speed up. Indeed keeping the speed up is the secret of taming the Salto.Therefor one would be forgiven in thinking the best wing section would be an F3F styled section.Thin flapped and fast. However the Salto is rather heavy beast with more drag compared to a F3Fr and requires a much liftier section. The full size does not sport flaps so if one is modelling a true scale model then a wing section change in flight is not possible.Aerobatic machines which fly as much inverted as the right way up or fly with their wings at zero angle attack will not have wash out to the wing tip.This would be counter productive at best and at speed create a negative twisting effect to the wing tip. Much better to build in a less lifting section at the tip to encourage the tip too continue to fly when the mid wing section is ready to stall.However in practice with the Salto's long thin span with one wing often flying faster then the other,(say on down wind final turn) the tip stall is never very far away. So as said we fly them down fast not slowing up until its directly into wind. At the point of touch down the full size will deploy a drag chute out the back if the pilot feels he may over shoot.
So why bother with a temperamental model I hear you ask? Well they don't arf fly well. `Check out this on YouTube



I don't believe that one could build a built-up wing complete with joiner system strong enough to withstand the viggars of the hard flying that a serious Salto pilot would put it through. (Valenta and Bouldis wings are mainly all carbon skinned with carbon main spar, glass fibre sub spars with an extremely large joiner approx 500mm long.

However if I was looking to build my own wing I would use quite a lot of modelers license and fit it out with flaps and conventional spoilers as per Valenta's. I would not fit the trailing edge brakes unless I was looking for scale fidelity.
I would also look at widening the tip cord a little but not to spoil its unique lines.I would choose the section suggested by Pat which is Ritz3 at the root.( Multiplex used this section on many of their models over the years including their famous Alpina.This becoming a firm favorite all rounder section to use) I would use this especially as the fus is molded for the similar Ritz1.already. From the inboard aileron-brake point out to the tip I would change the section back to the Ritz1 but also thickening the section a little.This because the extreme taper of this wing will undoubtedly make the tip very thin.

One last observation would be to discourage the use of polyester as a material for the fus.This material is well known to become brittle as it ages. even worse in cold weather. Epoxy is much more resilient and forgiving of our little mishaps then polyester ever is. I don't know of one other fuselage manufacturer who now still uses polyester. All the glass scale buffs know this and avoid polyester like the plague,or corona virus. Sorry Cliff.
I hope the forgoing has helped you decide your way forward, and I wish you and Cliff well in your project.
As I said at the beginning other will have a different view which would be great if we could discuss them here.

regards to all, Terry. (Purbeck Sailplanes)

[Peter Balcombe]

Many thanks for the feedback Terry.
The Salto in the video was certainly shifting

Certainly don’t want any washout at all on the outboard section then!!
Does the Valenta Salto use a High Carbon Steel round joiner?

A query on your mention of a 500mm long joiner.
Was that the total joiner length, with 150-200mm in each wing panel depending on fuselage width?
From my limited structural knowledge, I would have thought that you only need as much joiner in the wing as required to fully transfer the wing loads carried by the spar system into the joiner. The joiner is most highly stressed at the wing/fuselage interface if fully supported everywhere else.
Perhaps the Structural Engineers out there can put me right if I’m in cloud cuckoo land.
Peter

[terry white]

Hi Peter, The Valenta Wing joiner is a purpose made flat carbon joiner measuring approx 40mm wide x15mm deep x500mm long. It is free from the fuselage and pushes through flat to go in and out at will for transporting. Its upper side is of 40mm wide,the 15mm to go into the depth of the wing section with a little dihedral inbuilt in the wing. There is approx 200mm protruding into each wing .It slides through a very strong carbon box bonded inside the fus and likewise in the wing. The boxes in the wing are further bonded to the carbon spars and then carbon wrapped.
The 'D' box is of 150 gram carbon cloth with a slightly lighter weight cloth throughout the rest of the wing.
These measurements are approx as don't have the Salto at hand just now but they are not far out.

Another video for you. mark between 15-23 shows the wing joiner and the box through the fus. Terry

[Peter Balcombe]

Many thanks for clear explanation Terry.
As you say it is a very substantial joiner system

[SP250]

Peter

The Baudis Salto has a 25mm diameter x 630mm long carbon joiner.
The fuselage is 200mm wide at the joiner tube (215mm in each wing) and is tied into a height extended internal cover over the wheel, to brace the centre of the glass joiner tube inside the fuselage. The wing is thicker at the root and tip than the Valenta one and also has a 25mm or so increase in chord both at root and tip with substantial chord flaps and ailerons.
Mine also had a solid silver steel joiner as ballast which was 1.5kg and the carbon one was 0.5kg
Airfoil was HQ 1.5/15 at the root and 1.0/12 at the tip.
Hope that helps.

John M

[Jolly Roger]

We all love the Salto don't we?

I've never had a model one but in 2008 I was in Vermont and was mosying round an airfield, like you do... and I found a trailer with Salto written on the side. Well I had to peak inside, didn't I?...