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Sanda Models Mach 2 carbon (Set Up ?)
Konrad
Very Strong User
With the concept of floating spars, how do you guys address the connecting of the servo leads? I've glued the Multiplex connector into the tight fitting receptacle in the fuselage. I now see that there is no outlet for the servo wires in the wing root. I was going to cut a hole and epoxy the mating end of the Multiplex connector in place. Then I realized that this interface might float. I'm not sure how good a rigid mount would be with a floating spar. I'm assuming that it is the 4mm pins that really carry the alignment loads. If so there should be enough rigidity across the fuse to wing joint as to allow both ends of the Multiplex connector to be rigidly mounted.
All the best,
Konrad
All the best,
Konrad
I usually do not glue the plugs on the wings. Mostly due to laziness, but also should I have a large impact that pops the wing away from the fuselage, I would like to have a fighting chance to still land the plane. I have seen a few people unplug in air after a midair, but their wing was still attached. But mostly laziness for me.
Motowncali
Active User
In this case, remove the spar, make a paper template cutout of the multiplex connector, lay it over the connector, then locate the 4mm pins. Then you can slide the template onto the root of the wing, the pins will align and you can mark where the connector opening need to be. Next build, before you glue the connector into the fuse, put the joiner rod in and slide the one wind panel on, Mark the location through the connector opening in the fuse, repeat for the other wing...
Motowncali
Active User
If you can modify the template to account for the .3mm difference, then why make two. If you can’t we’ll then yes...
Konrad
Very Strong User
Well, I’m not the mechanic I thought I was! It took me 2 days to install 4 servos. And this was the second set of wings I have installed these IDS units.
I did learn form the unpleasant installation with the RCRCM Strega to reinforce the bottom of the top skin with carbon. This has made the servo mounting area much more stable! I’d like to see Sanda heck all OEMS add these carbon stiffening patches to the bottom side of the upper wing skins. I’m sure it would be much easier to do before the wings are clamped together.
I did make a mistake with the ailerons. That is that after I had glued in the control horn I found that the mono rod I had chosen was 3mm too short*. I knew I was making an error on the short side as an error on the long side would have meant having to cut into the spar web. So to make things look correct I made the same error on the other aileron. So by my maths 2 wrongs look right!
*The rods come in steps of 3mm lengths. ( I used the 4th up from the smallest, whatever it was the wrong one )
All the Best,
Konrad
I did learn form the unpleasant installation with the RCRCM Strega to reinforce the bottom of the top skin with carbon. This has made the servo mounting area much more stable! I’d like to see Sanda heck all OEMS add these carbon stiffening patches to the bottom side of the upper wing skins. I’m sure it would be much easier to do before the wings are clamped together.
I did make a mistake with the ailerons. That is that after I had glued in the control horn I found that the mono rod I had chosen was 3mm too short*. I knew I was making an error on the short side as an error on the long side would have meant having to cut into the spar web. So to make things look correct I made the same error on the other aileron. So by my maths 2 wrongs look right!
*The rods come in steps of 3mm lengths. ( I used the 4th up from the smallest, whatever it was the wrong one )
All the Best,
Konrad
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Konrad
Very Strong User
I spent the evening making up wiring harnesses. I hate to say this but I’m lazier than Wayne! That is I don’t want to spend a lot of time assembling the aircraft on the slopes. So to that end I’ll spend more time setting up the model on the bench. You can see that I’ve now glued in both sides of the Multiplex connector to automatically plug into each other when joining the wings to the fuselage. I have to thank Mo. That spreader tool you mentioned in Corsica thread is a god send. It has made the fitting of fuselages to the wing much much easier. I think it will also save a lot of wings. I’ve seen guys crush wings trying to get a good hold on them to pull them off the wing joiner. In my case there is always a bit of glue that bonds the wings and fuselage together when I do this auto align set up. I usually wait for the glue to set but not cure then I separated the parts and let the glue cure over night.
alofthobbies.com
Again I have to thank Mo for tell me that the with these IDS units he often needs to use the smallest servo horn on the ailerons. This saved me a lot of trial and error looking for the correct control horn to servo arm ratio.
You might notice that I narrowed the control horns by about 4 mm. I did this to minimize the rework needed on the wipers. Also these IDS units come with a real nice set of pins. You will notice that there is a small alignment bulb on one end. Make sure you use those bulbs when trying to drive the pins in place. Also don’t grind these off if you shorten these pins.
All the best,
Konrad
Wing Removal Tools - Servorahmen
Finally, a tool to remove stubbornly tight wings on our beautiful, close tolerance, moldies.They are pretty simple, a pair of smooth plastic wedges designed specifically for separating tight fitting wings from their fuselages, now available in 3 different
alofthobbies.com
Again I have to thank Mo for tell me that the with these IDS units he often needs to use the smallest servo horn on the ailerons. This saved me a lot of trial and error looking for the correct control horn to servo arm ratio.
You might notice that I narrowed the control horns by about 4 mm. I did this to minimize the rework needed on the wipers. Also these IDS units come with a real nice set of pins. You will notice that there is a small alignment bulb on one end. Make sure you use those bulbs when trying to drive the pins in place. Also don’t grind these off if you shorten these pins.
All the best,
Konrad
Konrad
Very Strong User
Well I hope these show up ok. What I’m trying to show is that the servo arms are biased aft in an effort to drive more motion in the downward direction (horns on the bottom of the flippers). I’m using basic geometry here. It is also known as the Ackerman effect. I’ve found that with “V” tails I get a more responsive rudder turn with this differential in the rudder. This is particularly true near the stall. Also with cambered airfoils I like more down that up motion. This results in a more balanced feel when flying inverted. It also helps with the rolls. I like to get this mechanically and then fine tune in the programing. Most high end radios like the FrSky X9D allow for these fine tuning options.
I’m real happy with the MP Jet connectors. Their pin fits most servo horns perfectly. They are small and the best part they are a metric thread. This makes it real nice to have all the hardware in a ship built to one standard. I always hated metric and english set ups! You might notice that with 9.5mm servo arms there is less than 0.5mm clearance with the fuselage sides. This why Sanda skew mounted the servos This actually moves the pivot point inboard a bit compared to side by side set ups. By the way the fuselage is one of the reasons I love the looks of the Mach 2. The cross section isn’t much greater than most 1.5 meter ships.
It looks like I’m almost done this the mechanical aspects of the build. All I have left is making the ballast hold down plug and glue the front of the bowden tubes down. I should be flying this ship by Tuesday.
All the best,
Konrad
I’m real happy with the MP Jet connectors. Their pin fits most servo horns perfectly. They are small and the best part they are a metric thread. This makes it real nice to have all the hardware in a ship built to one standard. I always hated metric and english set ups! You might notice that with 9.5mm servo arms there is less than 0.5mm clearance with the fuselage sides. This why Sanda skew mounted the servos This actually moves the pivot point inboard a bit compared to side by side set ups. By the way the fuselage is one of the reasons I love the looks of the Mach 2. The cross section isn’t much greater than most 1.5 meter ships.
It looks like I’m almost done this the mechanical aspects of the build. All I have left is making the ballast hold down plug and glue the front of the bowden tubes down. I should be flying this ship by Tuesday.
All the best,
Konrad
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Konrad
Very Strong User
Safety First!
I can’t count how many times I’ve seen servos become unplugged at the flying field! Usually not a nice out come!
Some guys like to use heat shrink as the safety. But I’m always afraid when I’m using a heat source around foam structures. Ernst use to make a nice plastic capture clip. But I don’t have the clearance between the servo and skins to use these.
What I really like is a simple non-waxed dental floss loop.
Just when I thought I was about done fabricating stuff I see this! The Jelly Bean is larger than the servo opening. Not a big deal just an annoyance. I’ll have to make up my own set. I’ll save these nice fiberglass jelly bean servo covers for something else. Note with the IDS I only need the a 2mm high jelly bean for the flaps. The ailerons will be flat covers.
I see I can slow down on this build as the F3F Thornton Beach race has been canceled.
To set the center of gravity at 80mm will take 125 grams of mass. I'm using an Aloft 2/3A 5 cell 1300 mAh rx battery.
All the best,
Konrad
I can’t count how many times I’ve seen servos become unplugged at the flying field! Usually not a nice out come!
Some guys like to use heat shrink as the safety. But I’m always afraid when I’m using a heat source around foam structures. Ernst use to make a nice plastic capture clip. But I don’t have the clearance between the servo and skins to use these.
What I really like is a simple non-waxed dental floss loop.
Just when I thought I was about done fabricating stuff I see this! The Jelly Bean is larger than the servo opening. Not a big deal just an annoyance. I’ll have to make up my own set. I’ll save these nice fiberglass jelly bean servo covers for something else. Note with the IDS I only need the a 2mm high jelly bean for the flaps. The ailerons will be flat covers.
I see I can slow down on this build as the F3F Thornton Beach race has been canceled.
To set the center of gravity at 80mm will take 125 grams of mass. I'm using an Aloft 2/3A 5 cell 1300 mAh rx battery.
All the best,
Konrad
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Konrad
Very Strong User
I may be wrong but as the ballast system is not a "standard" component I'd have thought that the stop would be included with the model. I made mine from an old worn out screw driver handle. I machined this with a drill motor hack saw and file just to prove I could do it.
I'm really liking the shape of this model!
As a lark (joke) I tested the cross section of the Mach 2 against my Mach Dart. And much to my surprise the Mach 2 has a much smaller cross section than my 60" racer the Mach Dart!
I'm really liking the shape of this model!
As a lark (joke) I tested the cross section of the Mach 2 against my Mach Dart. And much to my surprise the Mach 2 has a much smaller cross section than my 60" racer the Mach Dart!
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Konrad
Very Strong User
Well after digging through all my shoe boxes I've come to the realization that I don't have another G-RX6 and fitting a G-RX8 might be a bit tight with the 5 cell 1300 mAh battery. So it looks like I can't maiden the ship tomorrow. That's ok I'll spent time on the Mefisto. Yes, I have ordered 2 G-RX6. The other is slated for the Mefisto.
alofthobbies.com
Now my scales must be Off! All up weight is 1.47 kg. All the sales data I see quote an AUW of 1.4 kg. Hum, I now see that both the carbon and glass Mach 2 are showing the same AUW. That may be where my 70 grams is hidden. My Mach 2 is a carbon layup.
My initial center of gravity is set at 82 mm aft of the LE. I'll add weight to get a maiden CofG trim at 78mm, I'll remove this weight as needed to get the trim I want. I suspect it will be at 80mm. So the all up weight way creep up when adding the trim weight.
With lead as my ballast at full ballast I'm right at 2kg.
(Never leave the CofG at the manual setting, that's just lazzy!)
NOTICE: 78mm it the correct balance point!
FrSky GRX6 Vario Rx
The RX6R receiver incorporates all of the functions of X6R. It features 6 high precision PWM outputs and low latency. The PWM output is 9ms faster than the X6R in high speed mode. The RX6R also supports redundancy, this means you can connect another receiver as a back-up in the case that the...
Now my scales must be Off! All up weight is 1.47 kg. All the sales data I see quote an AUW of 1.4 kg. Hum, I now see that both the carbon and glass Mach 2 are showing the same AUW. That may be where my 70 grams is hidden. My Mach 2 is a carbon layup.
With lead as my ballast at full ballast I'm right at 2kg.
(Never leave the CofG at the manual setting, that's just lazzy!)
NOTICE: 78mm it the correct balance point!
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Glenn Beer
Active User
www.mcmaster.com Stock # 8859k38
21/32 [16.66mm] dia. brass tubing. Just .002” over 16.6mm.
I’ve always found McMaster to be one of the fastest turnaround hardware suppliers.
Edit: If you need that ring, there’s a part called a constrictor wheel that replaces the cutter in a tubing cutter, and allows rolling that groove into the tube.
I was told to design in metric when I started working 40 years ago. (Ret.) Unfortunately all the job shops just billed us to have the drawings redrawn in inch, because their machine tools didn’t have metric scales. Those redrawn prints often had errors. (Some people persist in thinking there are 24.5mm/in) We’d get bad parts, and have to rework them in house... argh Basically we had to wait until all the imperial built machine tools wore out and newer metric capable ones replaced them. It’s still a horror show. PS. you don’t really want to know how a 1/4-20UNC-2B tapped hole is called out on a metric drawing. Or worse on a dual dimensioned drawing.
21/32 [16.66mm] dia. brass tubing. Just .002” over 16.6mm.
I’ve always found McMaster to be one of the fastest turnaround hardware suppliers.
Edit: If you need that ring, there’s a part called a constrictor wheel that replaces the cutter in a tubing cutter, and allows rolling that groove into the tube.
I was told to design in metric when I started working 40 years ago. (Ret.) Unfortunately all the job shops just billed us to have the drawings redrawn in inch, because their machine tools didn’t have metric scales. Those redrawn prints often had errors. (Some people persist in thinking there are 24.5mm/in) We’d get bad parts, and have to rework them in house... argh Basically we had to wait until all the imperial built machine tools wore out and newer metric capable ones replaced them. It’s still a horror show. PS. you don’t really want to know how a 1/4-20UNC-2B tapped hole is called out on a metric drawing. Or worse on a dual dimensioned drawing.
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Konrad
Very Strong User
Did the maiden at the Sunset State Beach Camp & Fly. No drama! It was a nice pleasant flight. Now much to my chagrin the factory balance point is the proper balance point (78mm)!
I need to thank Mo and Wayne for pushing me to move the CofG forward to at least the manual starting place before the maiden.
I didn't need to ballast, so can't comment on that.
Loved the 90° flaps. The Mach 2 is very well behaved on landings.
If I have a complaint it is that the rudders are not as effective as I'd like. I think the "V" is set a bit shallow (I like the narrow V angles). I also think the ruddervators are a bit small in area. Now I didn't notice any wiggling or wandering in flight so the V tail looks to be properly sized.
I learned that the KST DS145MG servos are no longer available. I don't know what will be a replacement for a thin vertical mount servo.
All the best,
Konrad
I need to thank Mo and Wayne for pushing me to move the CofG forward to at least the manual starting place before the maiden.
I didn't need to ballast, so can't comment on that.
Loved the 90° flaps. The Mach 2 is very well behaved on landings.
If I have a complaint it is that the rudders are not as effective as I'd like. I think the "V" is set a bit shallow (I like the narrow V angles). I also think the ruddervators are a bit small in area. Now I didn't notice any wiggling or wandering in flight so the V tail looks to be properly sized.
I learned that the KST DS145MG servos are no longer available. I don't know what will be a replacement for a thin vertical mount servo.
All the best,
Konrad
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Motowncali
Active User
Great flying plane!
Happy pilot with a happy plane. Butter smooth. I had forgotten about the CG change! Yeah, really happy we caught that.
The KST 145 is replaced by the KST X10 Mini-710. Yeah, a bad name. I have suggested they call it an X10-H Mini to go along with the naming they use for the X08 servos. Good news is the new servo is better. The bad news is the price jumped up a bit.
Konrad
Very Strong User
The CofG wasn't that far off, only needed a 1/2 oz of lead. I'm sure it made a twitchy flight into a nice smooth one. I don't think the airframe was ever at risk.
I am impressed that Sanda has the CofG as far back as they do in the their manual. I'm sure this is to help with the placement of the ballast weights. I find that a ship that is nose heavy at speed, because of improperly place ballast, is annoying. At this CofG there is no shift in the balance point when fully loaded with ballast (530grams). (Still haven't flown her with ballast).
More back peddling from me! As you might recall I had concerns with how Sanda executed their floating spar. Well with Mo's hockey tape there were no issues, ether in flight or during the landing. So my comment about this looking like a design flaw was a bit harsh.
Now to do something about the color of than canopy!
Does "710" mean anything with this servo, power, speed, anything?
You are right! I'm very happy with this Mach II!
All the best,
Konrad
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Konrad
Very Strong User
Yep. I had to work some old turbine engine designs that where now on "New" designs. It was odd reading all those non standard metric call outs. New military specs are to be written in metric units. The regulation said nothing about adhering to metric standards.
Then add to the cost, the idea that some contracts were written cost plus XX% and we get spec's that had features like the radius called out to no known standard. This added to the cost for custom grinding cutters. But under a cost plus contract somebody made more money.
K&S the hobby supplier has these brass tubes. I'm sure 0.002 is well with in the tolerance band needed for ballast weights.
