Micro Sinbad

[Konrad]

He flies!

For very small values of flying. That is the backyard of a San Francisco victorian! I tossed the micro Sinbad in the backyard and near by baseball diamond.

I had to go with an external XJT module to get that dated VD5M to work with my Taranis X9D 2019 tx. But all appears to be good.

I was looking over the Sinbad and crying how tail heavy he is. CG is 45mm aft of the LE. Then I recalled that an airfoil knows nothing of CG it is the airframe. Seeing how large (oversized) the stab is. I was thinking heck many free flight glider of the same time era (40'S) had the cg as far back as 85% with their huge stabs!

So I talked myself into thinking it will fly with the CG at 45mm. I set my rates at 65% with an expo of 55 and tossed him into the wild blue yonder. Well much to my surprise he flew fine and responded the controls rather well. From shoulder height I didn't see any divergent flight. Back home I went, and drilled another hole in the servo arm at about 4mm. I had to do some monkey business to get the push rod to clear the servo output shaft. But I'm happy with the geometry. I set the dual rate for 100% 80% and 65% keeping the expo at 55 for the two larger values and dropped the expo to 45 for the low rate. A flight from shoulder height the elevator is a bit sluggish at 65% with the 4mm servo arm . But 80% is starting to feel ok.

Again these aren't even test flights rather test throws in between rain showers.

Now I'm really wanting to get him on the wing and see if he tucks at speed with the CG at 45mm!

Please note the windshield glare!

 

[Hank GB Z]

Hey Konrad,


Glad to hear the flight test program has started. Can’t wait to to hear more.

Hank

 

[JohnT]

WAIT! I just read through nine pages, with the last post in January. Konrad! You wouldn't just leave a guy hanging, would you?

John

 

[Konrad]

He flies! What more do you want to know?

Honestly there has been too much wind to fly this cute little bird. I will say, one (I) needs to place the CG much further aft than called out on the plans. (This is for my style of flying, low drag, point her where you want her to go. Sorry him! ). For a model based on a Free Flight I think the designer captured the essence of the Berkeley kit while making a fun R/C model (a bit of an advance build and slightly idiosyncratic flying). Don’t get me wrong, I love my little micro Sinbad but he is not for everybody.

There are some structural issues with the wing hold down (too draggy as shown on the plans). I don’t like the single line contact for mounting of the stab. And then there are the balsa grain problems mentioned in the thread. I think I covered how I overcame these few issues. The only real problem I see left is the choice of covering. Tissue and mylar may be the only practical solution for these Aloft micro gliders.

Upgrades are to move from a D-8 to a D-16 radio/receiver. Yes, he is well worth the upgrade.

Please note this was an early non-Aloft production run and a used purchase to boot!

 

[JohnT]

Again these aren't even test flights rather test throws in between rain showers

He flies! What more do you want to know?

Well, to be fair, the last post had been test flights. <grin>

Where's the video?

John

 

[Konrad]

I’m a Luddite! That is my hair is too gray, and I’m too old to learn how to edit videos. So I don’t do videos. If there is anything you want me to go over in more detail let me know. I’ll try to answer any question as best I can.

 

[JohnT]

@Konrad Read all your mods with interest. One or two I'd have to look at the original to figure out exactly what your were referencing.

How did flying go? Seems like Wayne, or Red, in my initial query thread about a slope micro, had said the Sinbad was kind of a 'one speed ship'. I built some of those Guillow stringer rubber band planes back in the sixties and, apparently, have something of a soft spot for them. They keep calling to me. <grin>

I'm no hand at editing videos either. I post them in all their original glory, with crud that should be cut out. <grin>

John

 

[Konrad]

All the micro gliders as rigged per the manual/plans are single speed models (more or less). There is a lot of performance hidden in the airframes that can be released just by moving the CG aft and cutting down on the elevator movement.

https://charlesriverrc.org/articles/field-and-flying/center-of-gravity-location/

I'd have thought that my write ups were self explanatory. If there are any questions as to the; what, why and hows of my mods please ask.

Wing to fuse junction drag with the dowels sticking out might take a bit more effort to explain than what is the focus of this forum. Do read up on junction drag.

The micro Sinbad will fly a lot like your Gentle Lady with the caveat that the fuselage has a lot more frontal area. The as drawn wing hold down is a lot more draggy than the GL. So in a race or thermalling against the Sinbad, the GL would most likely out fly the as drawn micro Sinbad.

P.S.
I too still build Guillow models.