TopModel Samsara 3.2 meter glider, build thread on Aloft's Forum.

[Konrad]

Collets all the way!!!
At my power setting I need the full contact area a collet affords us when driving power through a 4mm to 6mm shaft. Never mind that a set screw drives the assembly off center. As a machinist in a previous life I can tell you set screws are horrible at transmitting torque! They work fine for cutting a shaft

 

[Wayne]

Yep, and that used to be the only way you could buy the offset spinners. (cheaper and easier to make I guess.)

 

[Konrad]

Staying on the subject of collet (quality) "Z" hubs, Hanger 9 and E-flite have some spinners in the 38mm and 45mm size.


http://www.hangar-9.com/Products/Default.aspx?ProdID=EFLP16080FA
https://www.horizonhobby.com/14-x-8-folding-prop-with-aluminum-38mm-spinner-eflp14080fa

 

[Doc James Hammond]

Finally - here are some of my mods etc.

First, the servo frames. I used my own servo frame made from carbon filled Nylon by Nigel Wilkinson in South Africa. To be honest I did not like the little nibble bits supplied. I did remove the epoxy excess by the way.

By the way, the million wires you can see through the wing covering are me making servo wiring harness and nothing to do with this project! The wing is simply resting on the bundle.

 

[Doc James Hammond]

Next I ditched the supplies servo hatch covers...they really are quite large! Here I have made some mylar versions without the"Fairing"

 

[Doc James Hammond]

Then I decided to make the wing fixing with a replaceable carbon dowel in the front and just a simple nylon screw at the back.

Easy to replace the dowel in the event of an "Event" and/or the nylon screw at the back. No winch worries here so its all safe.

 

[Doc James Hammond]

Then, just to make sure, a carbon strengthening patch on the top of the wing.

Thats about it for the wing mods.

 

[Konrad]

Yikes, all that wiring gave me a fright.

I've often wondered about the effectiveness of the cover's hood. I know on racers we try to not have any of the control system in the slipstream. But if the arms, rods, and horns are in the airstream does the hood actually help cut down on drag? Or are the hoods just to help keep the weeds from damaging the controls?

On my wing front pin mounts I try to add roll off ramps. I find that vertical standoffs often keep the wing in place allowing the wing to leverage (pry) the fuselage apart.

As it looks like you cut into the sheeting can you tell us what you anchored the front mount to. And as I see you added a spreader plate to the rear bolt hole, I may do the same. As I'll need to have the covering iron out to get full travel from of the flaps.

Lets be brutally honest, we will have to replace flap servos. To that end I too like to use servo mounting plates. Aloft carries these.
https://alofthobbies.com/servo-tray-for-mks-ds-6125-glider.html
But as they often cost a large fraction of the price of a servo I only use them on flap servos. I still glue in most of my servos with a preinstalled cut wire (Dental floss).

All the best,
Konrad

 

[Doc James Hammond]

Hi Konrad - nice to talk to you.

OK, first I would like to point out that in fact the Samsara is really a very good plane as is, and its only my rough flying and the avilalblity of other parts I have for my own model line that makes me think about changing anything.

Here are some answers to your comments below:

-------

Yikes, all that wiring gave me a fright.

------

(JH) Hahaha - I made up over 100 wiring harnesses for my planes.

I’ve often wondered about the effectiveness of the cover’s hood. I know on racers we try to not have any of the control system in the slipstream. But if the arms, rods, and horns are in the airstream does the hood actually help cut down on drag? Or are the hoods just to help keep the weeds from damaging the controls?

-------

(JH) If the fairing is on the bottom of the wing, then a good one is quite effective as the bottom part is often operating in actual laminar flow - in this case anything you can do to remove or reduce bumps etc is good.

On the top of the wing its a different story. Even fast F3f racer the upper surface of the wing is never actually laminar. Its not until we get to the middle DS speeds that it can happen. Normally the boundary later will separate at about 40% to 60% on the top surface, so any fairing you have after that is not helping at all.

------

On my wing front pin mounts I try to add roll off ramps. I find that vertical standoffs often keep the wing in place allowing the wing to leverage (pry) the fuselage apart.

As it looks like you cut into the sheeting can you tell us what you anchored the front mount to. And as I see you added a spreader plate to the rear bolt hole, I may do the same. As I’ll need to have the covering iron out to get full travel from of the flaps.

------

(JH) I just made box and cut it completely down into the wing structure and glassed and epoxied it in.

-----

Lets be brutally honest, we will have to replace flap servos. To that end I too like to use servo mounting plates. Aloft carries these.
https://alofthobbies.com/servo-tray-for-mks-ds-6125-glider.html

-----

(JH) If you look at the pictures you will see I have already done this. I used my own servo trays but these are not commercially available - Waynes trays are great.

-----

But as they often cost a large fraction of the price of a servo I only use them on flap servos. I still glue in most of my servos with a preinstalled cut wire (Dental floss).

-----

(JH) Well as I said, I do have parts available so I use them.

All the best,
Konrad

 

[Doc James Hammond]

Here is some of how I did the fuselage.

First I made the rudder linkage from the fuselage - I did not use the servo in the fin option. Here I simply used an old spare fairing I had from a while back:

Then I made the tailplane tray a bit stronger:

Here are the two back end servos installed:

More coming!

 

[Konrad]

I agree fully, the Samsara is a fine, even a great ARF as shipped. That is why I bought her.

What we are doing here is bringing our preference, from years of experience, to bear as we assemble the model(s). I post to share and learn from others as to what works best. Now I apologize if my questions appear to undermine one's own method. That is not the goal of the questions. I question to get answers for my greater understanding.

I now ask why the under wing mounting of the rear servos? Was this a problem with the shorter servo arm length as a result of the thicker E-max ES08MA servo? Or was it to use light, very high "C" rated, 1500 mAh to 1800 mAh batteries? What is the weight of your plane with the CofG stated on the plans?

All the best,
Konrad

 

[Doc James Hammond]

I agree fully, the Samsara is a fine, even a great ARF as shipped. That is why I bought her.

What we are doing here is bringing our preference, from years of experience, to bear as we assemble the model(s). I post to share and learn from others as to what works best. Now I apologize if my questions appear to undermine one’s own method. That is not the goal of the questions. I question to get answers for my greater understanding.

I now ask why the under wing mounting of the rear servos? Was this a problem with the shorter servo arm length as a result of the thicker E-max ES08MA servo? Or was it to use light, very high “C” rated, 1500 mAh to 1800 mAh batteries? What is the weight of your plane with the CofG stated on the plans?

All the best,
Konrad

Hi Konrad,

Apologies? None needed. This is Aloft...we are all polite here!
Undermining? Where?

Experience?
Hmm...Well I'm not sure about my years of experience in this case...

Modelling?
Yes, very experienced since I have been doing it since I was 9 years old, and I'm 66 now.
Competition C/L? Since 1965.
Designing R/C Sailplanes? Since 1972.
Moulded R/C sailplanes? Since 1975

But electrics?
No - this is only my first ever - though it might seem weird to say I have designed a few electrics. E-Typhoon, E-Strega, and a couple more when I was working with RCRCM years ago.

Why did I mount the servos where I did?

FEAR.
I am a bit afraid of cramming too much stuff up front because I don't know what I'm doing.
Half of the people I asked said just use the big battery and a BEC, other said Noooo! Use two batteries if you can! So I thought, better provide for both. Logically it makes sense to have the largest battery possible - but that about as much as I know.

The Motor/Prop/spinner was a bit easier as it was recommended by Wayne's guys.

I'll post some more fuze pics later if I can ever find my way out of this birds nest of wiring harnesses!

Cheers,

James.

 

[Konrad]

Well, I think I found the flap issue with my particular kit. That is that my flaps were covered and taped to the center section upside down.

These flaps and ailerons are basically just 55mm wide solid balsa trailing edge (TE) stock. From the balsa mill this stock has a 90° corner, basic standard stuff. To get the 2mm to 3mm reflex stated in the manual this TE stock is to be installed with the 90°corner towards the top surface of the airfoil. Or, put another way the flap is to be hinged on the bottom using the less than 90° corner.

If the flap is hinged with the 90° corner on the bottom there is no relief on the top of the hinge line to allow the flap to reflex the 3mm stated on the plans.
So when hinging your flaps make sure the 90° corner is towards the top of the airfoil.

Now I like to use my flaps as ailerons so I will be adding more relief to increase my roll rate.

Sorry for the poor drawing, I really didn't want to find my computer that has my drawing program loaded on it

 

[Doc James Hammond]

Aha!
my are hinged a little looser and can give me a little bit - maybe 6mm - of reflex.

Might be an idea to cut them free and redo the hinges? Easy and quick job.

Cheers,

J

 

[Konrad]

6mm is twice as much as shown in the manual. Probably don't need much more than 6mm for the flap as aileron mix.

I think I'll go for about 10mm to 12mm and cut it down if the flight tests show that this much flap deflection (as ailerons) slows the plane down rather than increases the roll rate. As you know this is all part of a trimming and set up.

All the best,
Konrad

 

[Doc James Hammond]

6mm is twice as much as shown in the manual. Probably don't need much more than 6mm for the flap as aileron mix.

I think I'll go for about 10mm to 12mm and cut it down if the flight tests show that this much flap deflection (as ailerons) slows the plane down rather than increases the roll rate. As you know this is all part of a trimming and set up.

All the best,
Konrad

Here's mine Konrad.

Looking at it, its probably more like 10mm.

Cheers,

J.

 

[Doc James Hammond]

Here are some more of my nose pics!

Note this has 1.5 degree side thrust and 1.5 degrees down thrust.

To be honest I'm really not sure it is needed but I bunged it in anyway.

Cheers,

James.

 

[Konrad]

That looks about right for the amount of up flap I'll be trying to get.
Motor thrust sounds about right. Using the wing mount as my datum I too have measured with an inclinometer a 1.2° to 1.5° of down thrust. With the Mk I eyeball I have 1°+ right thrust. Really these numbers are to insure I don't have any up or left thrust lines.

Note: The manual shows the wing placed at 1.5° positive incidence. I assume this is measured at the wings chord line, not by the bottom of the wing. The manual does not state what is used as the 0-0 reference datum. I assume it is the stab.

A benefit to installing your own firewall is that you can control the placement of the motor leads. As I have some down thrust this means that there is more clearance on the bottom than the top for the motor leads. I position the firewall so that when the motor is bolted on the lead can pass along the bottom, away from the rotating can. In my case I have the bolt holes at the 45° clocking point. I learned years ago when using plywood as a firewall that the 45° bolt patten was more durable, as I had two bolts fighting against the landing forces that where trying to push my motor up through the top. Also I got a bit more stable a platform for making up and right thrust adjustments as I could use a washer on the two appropriate bolts.

I like that it looks like your battery is place a bit aft, I assume this is at the 65mm balance point.
Nice touch with the switch mount.

All the best,
Konrad

 

[Konrad]

Now I see what James was complaining about when he said the covers were too thick. There really is no need for these drag bumps. I'll be replace these covers with these from Aloft Hobbies. https://alofthobbies.com/servo-cover-large-flat.html

 

[Doc James Hammond]

Now I see what James was complaining about when he said the covers were too thick. There really is no need for these drag bumps. I’ll be replace these covers with these from Aloft Hobbies. https://alofthobbies.com/servo-cover-large-flat.html

View attachment 234

I think those might be much better. To be honest I'm not expecting any speed records from this model so I'm not too worried about the minimal drag at the bottom - but really, they are a bit big as supplied!

I think you are right about the firewall orientation too - just did not occur to me. Experience cannot be taught!

Actually the battery is simply where I put it to take the pic. The final position should be somewhere around there but I have not balanced the plane yet as I have been a bit busy with other things.

Thanks for the continuing good info - and the other good thing is that most of this applicable to a lot of planes.

James