Sanda Models Mach 2 carbon (Set Up ?)

[Konrad]

I just picked up a Sanda Models Mach 2 carbon from Aloft Hobbies. I have to admit I've seen this model before but discounted it thinking it was a bit too expensive for a 2 meter. It wasn't until I realized that it is a 2.4 meter that its value became clear.
https://alofthobbies.com/mach-2-carbon.html

This is looking like a great front side glider. Now that I have her home I have a few question for those that have assembled one. First what servos fit the fuselage servo tray. The cutouts look too large (wide) for the KST 145. Also what do you guys use as a ballast system? It looks like the installed ballast tube is sized for 17mm slugs. It also looks to require a tabbed anchor for the ballast. So far the only quality issue I've noticed is that the V tail wipers are just tape. These really don't look like they are up to the standard set by the rest of the model. (They may be fine for the expected elevator movement. But as I like all the rudder I can get, I'm sure to "pop" these wipers) Also their V tail horns (wire) looks troublesome.

A plus, I didn't expect, was that the model is sold with wing bags.

While I don't plan on using the Mach 2 as a DS ship, I'm sure I might try some lighter DSing during its life time. Anybody have any concern with the size of the wing joiner?

Based on Hammond's review I'm going to try to install this linkage with the KST DS135 servo in the wing. Anybody have a suggestion as to which servo arm to use.
https://forum.alofthobbies.com/inde...ds-servo-mounts-etc-step-by-step-install.198/
https://alofthobbies.com/ids-kst-mono.html
https://alofthobbies.com/kst-ds135mg.html

As this isn't a new design I'd like to hear from anybody that has setup, owned or flown one of these Sanda Mach 2 carbon ships.

TIA,
Konrad

 

[Konrad]

What is real refreshing about Aloft Hobbies, is that Wayne would like the review of the products he sells discussed with a slant towards helping anybody/everybody get the most from their purchase. He actively encourages that everything gets discussed, warts and all. He is of the opinion that an informed customer is in a better position to make the proper choice in his/her purchase.

To that end this set up thread will also address features and issue I find in the kit. I want to be clear that this is great front side slope ship. But as it is made by man there will be issues that could have been address differently and maybe even more appropriately. Yes, much of this is a personal preference and much of these are driven by economical realities. So because I point out something, doesn't mean it is a terrible flaw.

You might have noticed that I call this a front side sloper. An issue with molded gliders today is that many folks are looking to compare all against DSing ships. Front side sloping and Dynamic Sloping (DS) ships have very different demands put on the airframe. The Mach 2 carbon to my eye is not a DS ship. She will fly fine DSing at the lower speeds but is not designed for real high speed DS work.

While the wings look flat in many of the photos, I didn't realize until Wayne pointed it out, that they actually are sporting a polyhedral. I'm hoping that this will give the Mach 2 carbon a very nice line while cutting a pylon turn at the end of the legs. While at the same time keeping the rudder roll coupling in check. These wings are what should differentiate the Mach 2 from whatelse is in the market place. Based on the spar design (carbon caps with full width balsa shear webs) the aspect ratio of the wing looks appropriate for this mid size slope ship.

The as designed joiner looks appropriate for the weight of this model. As the Mach 2 is not an F3F or DS ship there is no need to be carrying as much carbon as we find in a West Virginia coal mine! But my spar has a major manufacturing flaw. That is the balsa core moved out of position during the lay up that for much of its span I have a "C" shaped carbon center spar rather than the as designed box spar (joiner).

Now I'm a bit odd, in that for my front side ships I like to see voids in the surface finish. This to me indicates that the OEM did not use too much resin in the lay up. It actually is rather difficult to maintain the proper ratio of resin and fiber content while laying up components. Far too many OEMs error on the side of using far too much resin as it results in a nicer finish. If you have met me you would know that I hold to the notion that form follows function, or that I put little value on aesthetics. This might explain why I'm such a slave to fashion, NOT!

My wings are also showing a manufacturing issue as the knife slipped when the flaps were cut free from the wing. This is only an aesthetic issue as none or few of the fibers were cut.

Another quality issue I found was that my V tail control horns are not bent crisp, all the legs show bows. Also the bearing surface on the balls of my horns are contaminated with solder. I will need to clean and polish these prior to installing them into the V tail.

I like that the servo covers are made from fiberglass layups. Most covers at this price point are made from vacuum formed plastic. I'm impressed that Sanda carried the color scheme to the covers. (Note the one white one)

 

[Motowncali]

I’ve found so far that on the IDS trays and set ups I’ve done, the shorter the better. Even using the shortest servo horn, I’ve had to turn the travel adjust down. When not using the IDS tray, I’ve been drilling out the dimple in the KST red control arm.

 

[Konrad]

Thanks! That helps a lot.

 

[Wayne]

For the tail, I'm pretty sure we sold you some of the KST 215 or the Daviga 213 servos. They are both the same size. Anyhow, they are my go to servo for tails, they are nice and fast, and plenty of torque for the tail. They should be a pretty close fit to the holes in the servo tray in the Mach 2.

I don't think many of these planes have sold in the USA, so you may have some fun finding anyone that has built one. But, there is nothing to different from your other moulded gliders. It should go together pretty nicely with the exception of that tail linkage. We now order our planes from Sanda with the linkages already installed. If you like, I can see about getting a new joiner from Ivan, but it might be a while before it would arrive.

 

[Konrad]

Wayne,
Thank you for the offer. Please put a joiner on your next order with Sanda. But to be honest it will be a while before I think I will be flying as hard and as fast as to put the current mis-manufactured joiner at risk of failing.

WOW, you remember what you have sold me! The 215 and the 213 are a bit short to fit the holes in the servo trays, easy enough to fix with some filler pieces and glass reinforcement.

I don't think the tail torque rods (linkages) should be any problem.

 

[Konrad]

Found another quality issue with the model. You might notice that the fuselage receptacle for the wing joiner looks to be oversized by 1 mm to 2 mm. This allows the fuselage to move out of alignment relative to the wing. That is the tail goes all over the place. The only thing that is indexing the wing to the fuselage are the small alignment pins. I don't think these were intended to carry the whole load of the wing to fuselage junction. And surely not sufficient support for landing loads.

Looks like I'll need to fill in these voids while keeping the wing joiner and fuselage aligned.

May need to also address this issue.
https://forum.alofthobbies.com/index.php?threads/manufacturing-design-flaws.365/

 

[Wayne]

Actually, that is a design feature of this plane. This is something Sanda does on all of his planes. They are floating joiners. I know it seems really odd, but it does seem to work fine. He does it on his larger planes too.

 

[Motowncali]

What Wayne said. This is not uncommon on sailplanes. The joiner connects the wing panels together and the pins hold the wings in alignment on the fuse. Be sure to use good quality tape to hold the wings onto the fuse.

 

[Konrad]

Wayne,
Thanks.

I've seen floating spars on full-size gliders. These allow the wing to move in one direction through the glider fuse.

What I'm seeing with the Mach 2 is that the spar (joiner) is free to move in all three axis. This is making it all but impossible to keep the tail in position while I'm trying to rig the model. I can only guess how difficult it will be to keep in trim during flight.

I'm looking at the joiners on my FVK, and even Doc's Aeroic brand, models which seem to need the joiner frozen before sliding into the fuse. Nice tight fits.

I fear that the loose fit allows more movement allowing for more twisting /leverage damage to happen against the fuselage on landings

All the best,

Konrad

P.S.
Mo's Hockey Tape might help keep her together.

 

[Motowncali]

Am I to understand that not only does the spar move up down, for aft, but slides left and right so the center of the spar which has dihedral in it moves from side to side?

The left to right not locking the dihedral in the center, can be fixed by making a pencil mark on the spar when it is centered in the fuse, then slide it into each wing panel to see how much deeper the socket is. Add balsa block to the end of the spar to fill the difference. Label L and R if the wing sockets are different depth.

 

[Konrad]

The spar (joiner) for the Mach 2 is straight so the movement span-wise is not an alignment issue.

The spar can move UP and down 1mm, fore and aft 2mm, rotate about 3° to 4° viewed from the front, and rotate about 2° to 3° viewed from the top (Yaw).

The joiner can also rotate a bit fore and aft, but this should be held in check by the wing pins when the wings are fully seated.

*I could trig out actual movement but I'm more concerned that the joiner and receptical don't hold the tail in proper relationship to the wing. Now the wing roots and fuselage fairing do look to index the fuselage properly. So the use of heavy tape may work.

 

[Konrad]

I've seen a lot of folks have difficulty with the servo wires interfering with the mounting of the servo. I don't understand why OEMs so often put the servo leads where they do. I loved that the real Multiplex servos often had the leads running along the side in a groove to clear the mount. I also like the D47 servo for this feature. I like that KST on the XO-8 series of servo has then out of the way (pointing down wards).

The problem is that guys tend to make a relief cut in the tray to allow the servo wire strain relief to pass through the servo tray. This is fine until you want to screw down the servo to the tray. There is little or no tray under the servo mounting holes!

This is my solution to the well fitting servo tray installed at the Sanda factory for my Mach 2. I'm using KST DS145 servos. By making some notches that allow me to skew the servo in the tray. This allows me to use the other servo's clearance to pass the strain relief. Or move the strain relief notch away from the mounting holes.
https://alofthobbies.com/kst-ds145mg-servo-5-2kg-72-2-oz-in-10-sec.html


I still have issues with most modern servo OEMs not suppling vibration isolation system for power applications!

All the best,
Konrad

(Problem tray photos found on the internet).

 

[Wayne]

Good method.. I too hate that issue!

 

[Konrad]

With the cancelation of the 60" MOM race I had a day to work on some projects.
I bent the wire V tail arms to get a more than just a glue bond with the wires and the elevators. I also found that when installed, one arm is longer than the other (distance of sphere from the hinge line). This was easy enough to fix, just by heating the sphere and moving it 2 mm. (Note the solder is electrical, not high heat or strength silver braze).

 

[Konrad]

Again I need to give RalfH a call out and a "thank you" for suppling me with 15mm copper coupler 16.6mm OD. These fit perfectly in the Sanda supplied ballast tube. Filled with lead mine come to 53 grams each. 10 slugs means I can ballast the Mach 2 with 530 grams of ballast. This is assuming that I like the CofG marked on the ballast tube. I now need to find another 10 or 20 of these.

When will the USA join the rest of the world and throw away the imperial system? Nothing around here fits anything. This is a piss poor way to run an economy and try to be a member of the global community!

 

[RalfH]

Hi Konrad, glad these work out. If you need more, I'm likely headed east again over Christmas, though that is a bit far away...
Has anyone tried to make a form from on of these and cast them? Likely won't have a nice surface finish like the copper fitting though

Ralf

 

[Konrad]

I guess one could do that. But the as cast led is soft and will like get beat out of shape rather easily. I also like that I can keep my contact with the lead lowwer with the copper sheath. I still need to paint the ends of mine.

Thanks I hope I can get a source before Christmas, but....

 

[RalfH]

good point about deformation. I poked around some plumbing supply sites, found these guys:

Metric Copper Couplings ( Pipe/Tubing OD )

Metric Copper Couplings

coppertubingsales.com

a bit pricey though...

 

[Konrad]

Yep, but I liked the ones you supplied, as they have a full circumference indentation band.