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thermaldoctor

Samba Prestige 2pk build

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thermaldoctor

As many will know the new Prestige 2pk is the very latest model from Samba. It is also their first model exclusively dedicated for F5j and not an F3j model made lighter for F5j. The overall concept and  goal in both classes though is actually similar but go about it in different ways so we are now seeing purposely designed models for F5j that are now fitting the task noticeably better than previous cross-over type models.

And the Prestige is most definitely one of the new breed. At the very first 2019 F5j WC in Trnava there were one or two models that just looked a bit better and a bit more comfortable and not struggling against other models in the slot over a week of very different conditions and the Prestige was one of them.

With the many different proprietry Philip Kolb designed airfoils and planforms running through the rudder, elevator and main wing it is arguably the most aerodynamically sophisticated f5j model available at present and definitely one of the top choices if you are after the very best in performance that current technology and aerodynamics has to offer. 

But this is not without its compromises.. 

The Prestige 2pk uses Rohacell solid core wing technology for the ultimate in light weight, strength and stiffness from such thin low drag wing sections but it is prone to denting more easily than conventional hollow moulded technology. It also means you have to bore your own holes in the  Rohacell cores for pushrods and aileron servo wires (centre panel comes completely done with wiring for you) but for anyone with proper traditional modelling skills it will be a breeze.

The fuselage is super skinny to offset the drag of the prop compared to a pure glider fuselage and although there are performance gains to be had, it makes installation very tight and a pig compared to traditional older fashioned layouts but once done and the swearing is over it is very neat very slick.

Here is a pic of my final fuselage installation. Read next time how we got there....

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PeteMitchell

Wing dents can usually be removed using a damp/wet paper towel laid over the dent area, and carefull use of a covering heat iron.

The iron needs to be hot enough to  cause the damp paper to steam. The steam expands the foam and returns the surface to undented condition.

If the dent is in a painted area the steam can cause the cloth weave to show through the paint.  And if the dent is a  'sharp' one, caused by   i.e. a heavy tool being dropped on the surface,

the dent will probably never be fully removed. So dont do that!

 

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thermaldoctor

The Prestige fuselage comes with pre-moulded in servo trays intended for the MKS 6100 servo format. Unless very close to these dimensions servos will not fit without some major surgery. But there are one or two others that will fit from KST, Bluebird. Not wishing to fit these brand of servo i elected for some major surgery. But there was another reason going for major surgery - my first Prestige to put together is a windy lay up one with 4s 1kw set up. So I figured flying forward at full power into  a strong headwind will give quite a high airspeed plus possibly quite turbulent conditions. Therefore I did not want to run small 9g servos on the large rudder and elevator surfaces. It would be like ramping a Fiat 500 down the motorway at 100mph. So i fitted larger 12mm servos with bigger stronger gears and nearly twice the torque.

The major surgery involved cutting out the existing servo trays (but leaving the two ledges each end) and fitting my own from 1mm carbon. It was self inflicted pain but the end result is worth it. But I wouldn't suggest people going down this route unless they really wanted to.  My normal and light Prestiges will use the Kingmax 0309W's which are 8mm 3kg items and should be fine and will fit with only minor effort.

Below is a good look inside the fuselage that not many will ever see as here we have it without the pre-moulded trays and all cut out.  You can see the Textreme spread tow carbon on the fuselage floor and on the left hand side just under the ledge is the carbon ballast box bonded in place.

As it comes the carbon pushrods need the threaded couplers glueing on and clevises fitted in place. For me this was much easier than normal as I did it before I glued my servo plate in so had easy access . As I would not necessarily suggest people go down the route I did I would refer you to Ali at Flighcomps video on how do a conventional fuselage servo install. I have also put together a conventional Prestige together for a customer and Ali's method works well.

A good suggestion thanks to Martin Gilbert for at least the rudder is to pull the end of the pushrod forward clear of the fuselage and fit your coupler/clevis/horn first. Then push it back in place, line it up with the servo, and then chop the pushrod and  fit the rudder ball link last of all. You can also do this for the elevator but will need to chop off the pre-glued elevator ball link and then fit another once you have done the servo end and lined it up. There is plenty of length on the pushrods to do this.

 

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The servos I wanted to fit were 12mm 5kg items. But being meant for vertical fuselage mounting I needed a way of fitting them flat to a horizontal surface. I opted to cut some 1mm thick carbon angle from Easy Composites and after roughening up and degreasing both surfaces thoroughly I used thick slower setting cyano to make up chassis mounting type holes. I did this for one side of each servo and then for the other side of each servo i used the same 1mm carbon angle bonded to each fuselage ledge with screw holes drilled on  the vertical faces to bolt the servos to

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mikef

That looks like fun.  How do you get the servo horn retaining screws in?

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thermaldoctor

The end result worked out like this and for me was well worth it for 1KW dedicated windy weather model. But as mentioned quite a major effort and perhaps way over kill but I am happy with it.

The receiver sits in a pre-moulded bathtub set into the rear of the fuselage. I like this idea very much but it has been poorly executed if you don't have a receiver that will fit. Space is quite tight for some receivers (mine are Multiplex) so be prepared to get the heatshrink out to get it to fit. I have seen a number of receivers fit perfectly however, so just like for the servos it seems to have been designed around the most popular sizes. I have seen JR, FrSky, and Futaba fit just fine.  What you will need to do for all receivers however is cut out the front face of the receiver bathtub to allow for the connectors. At the rear you need to make provisions for the aerials.

The wiring loom comes pre-done for you and all you will need to do is cut out the rectangular hollow moulding into the fuselage and glue in the connector. To do this I plugged it into the wing (the wing one comes ready fitted in the mould) and then bolted the wing to make sure it all lined up and making sure to use a smearing of grease to stop gluing the wing on.

 

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The rudder comes as a separate moulding and is designed to be de-mountable for easy storage and transportation. As standard it is simply a friction push-fit on and retained with a single screw on the bottom. Further rotation is prevented by taping the fuse/fin joint. The engineer in me was not comfortable with this, particularly for a windy weather model facing strong crosswinds and 1KW of prop wash so I decided to line the fin up an bolt in place. Then use a pillar drill to drill vertically through the fuse and fin at the joint. Then use a carbon rod glued into the fuselage projecting just enough to locate the two slots made in the fin. This worked perfectly and put my mind at rest but again...maybe overkill. Would you need to do this? Probably not I think I am the only pilot to have done this but it certainly cant do any harm. I won't be doing it for my normal and Light versions it was just for the windy model.

The screw now is there just to stop the fin falling off. All rotation is now taken care of by the rod and slots. With regards to the screw I had to open out the hole in the bottom of the fin to allow the fin to sit perfectly vertical. As it was the fin was at an angle which was unacceptable. I have spoken to Samba about this and all future models will come perfectly jigged.

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thermaldoctor

At the back end more material was needed to be taken off the pylon part of the elevator slot to allow full down elevator. As it came it had just enough down elevator but i dremelled it out further to allow the elevator to just touch the top of the fuselage ie absolute maximum. I like to have enough down elevator for full brake compensation and then also a further as near to full travel movement to nose the model over onto the spot if needed. While i was there I also widened the slot to make sure the elevator rod could swing freely at maximum travels without catching the sides.

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In this picture you will also note a tailplane seating. This is not standard. As it comes the tailplane seats on top the slim pylon and again the engineer in me rejected this because of any lateral loads will only be spread over a very narrow seating area. Although the tailplane is quite hard at the mounting points the idea came from the Osprey 2 which has a nice wide 20mm tailplane saddle that works really well and gives very firm support for any lateral loads applied to the tailplane. So the idea was transferred to the Prestige with great success and perfect for a windy weather model that will be experiencing a lot of turbulence and prop wash. Again is this totally necessary? Probably not but it cant do any harm and i feel much happier having done it. Most likely i will not bother doing it on my standard and light version.

As it came my tailplane was slightly out of alignment and it needed small work with a file to align. This was unnacceptable but speaking to Samba this is now fully corrected. 

To finish the rear  end off the rudder slot needs opening out to allow full and free movement, the ball end bonding on, and job done. 

20200707_174713.thumb.jpg.ca78926437efdf3f6c868bea25880652.jpg

 

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PeteMitchell

My one is a standard setup, more or less as recommended by Samba.

Jeti R7 fits perfect 🙂 

PrestigeServos.jpg

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thermaldoctor

Looking good Pete..

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