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Old Apr 23, 2002, 05:49 PM
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Winchester; Ohio
Joined Feb 2001
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Sagitta XC Electric ! 174"!

Hi Guys; I ordered this a while back from Dream Catcher Hobbies. A Sagitta XC short kit. This is a 174" RES glider from Airtronics from several years ago, 1980's.
I had been looking for a BIG floater for a while and had planned on a Sailaire kit but they were out so I went for the short kit of the Sagitta XC.
I plan on using a motor to get to altitude so Im sure some planning will need done in the fuse area. Im not going for anywhere near vertical performance by any means. Just enough cells/watts to get to altitude 2 or 3 times climbing on the wing.
Ive gotten a few good tips from Ramair as he had a couple of these when they were out.
Any one else fly one or do a conversion on something similar?
Ive seen pics of a similar sized plane that Vonbaron posted some info on so I wont be the first
This is going to be my summertime between flying cutting grass etc project so I expect it will be drawn out for a while.
Adam
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Old Apr 23, 2002, 07:41 PM
allergic to castrol oil
ontario canada
Joined Jan 2002
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next fall

hey adam, i hope it goes well for you because next fall im thinking of the xc also with electrics
i have a new sagitta 900 for now,i flew it last week and was very impressed. i think you will be glad you picked the xc

ramair
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Old Apr 24, 2002, 04:47 PM
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Winchester; Ohio
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Well I got lucky on this. I just found out at work we have a copy machine for blueprints
Up to 36 " wide and any length. I was able to run a couple copys of the plans so I wont have to cut up the originals to get it built.
I was going to see about having this done at one of the copy centers but free is much better
Adam
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Old Apr 25, 2002, 08:51 PM
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Santa Rosa, Northern CA, USA
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Hi Adam,

Not sure if this has been dealt with on the new kits, but the older Saggita XC would shed its stab at higher speeds. The plane would tuck, and then the wings would fold. This normally happened during XC runs, where the plane was so high you could not see that it had gained to much speed. So, be careful with you speed !!

For motors, if you climb on the wing, you won't need much for power. About 35 watts per pound should work. The glider takes lead up front, guessing about a pound (does anyone know?) so motor weight is "free".

If you want to go cheap, an old geared Astro 40 should be fine on 12 to 14 cells.

Can you post the normal flying weight as a non-E glider?

Regards,
Dave

PS: I have 2 Sag 900's and 1 Sag 600. Nice gliders! Here's my 600
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Old Apr 25, 2002, 08:59 PM
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Neat Modification

Adam,

Guess you will build the poly version. If you do spoilers, Top & Bottom spoilers are real SWEET !!
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Old Apr 25, 2002, 09:06 PM
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They act as spoilers & airbrakes and reduce that pitch down problem of top spoilers only. Also slows the plane down, which top spoilers do not do.

I like to use carbon plate bottoms with a thin balsa top that is sanded to the airfoil shape.

Like this
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Old Apr 26, 2002, 06:34 AM
allergic to castrol oil
ontario canada
Joined Jan 2002
143 Posts
shed stab

yes adam ,i hope you remember the stab mod. i warned you about!!, im told that if the pivot pin is to the rear, it causes a horriable fludder,enough to blow off the stab!i witnessed that one myself!!!
also, its at least a lb of lead in the nose!


ramair
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Old Apr 26, 2002, 08:57 AM
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Winchester; Ohio
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Thanks for the input guys;
Dave; First, Nice pics I am building a poly version and I will be adding spoilers, which type I dont know yet but the split ones look good!
They are calling for an AUW of the glider at 8lbs or 128 oz

As for the issue of the stabilizer the plans show a pivot point about midway and the servo connected via a cable to the front.

I can see several options here to keep this from coming apart.
1) Build per the plans and eliminate the cable; mount the servo in the tail and have a direct linkage to the front of the stabilator.
2) Build a non-flying stabilizer with seperate elevators.
3) Built a T tail with a seperate elevator.
4) Do something else?

Just a note here; This is a short kit that is only a set of plans and a set of ribs. The rest is in the open as far as any mods or deviating from the plans.
Adam
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Old Apr 26, 2002, 09:19 AM
allergic to castrol oil
ontario canada
Joined Jan 2002
143 Posts
bellcrank

adam; on some of the newer sagitta`s,900/600 they changed the stab to a bellcrank system but the main differance was that it also just reversed the pins eg;the stabs pivit on the front pin and then attached to the push rod at the rear
the stabs where not changed at all or nor was there position.
the new mod. uses the hollow section of the fin for the enclosed bellcrank,therefore giving you a reduction and the option to use a solid push rod
i would try to resist puttin a servo in the tail because the plane will all ready require nose weight
i also suggest using a strong metal gear for the rudder servo,its got a lot of rudder and brakes on landings if not centered[rudder skids the ground]


ramair
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Old Apr 27, 2002, 10:09 PM
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Quote:
Originally posted by Adam Neat
Thanks for the input guys;
Dave; First, Nice pics I am building a poly version and I will be adding spoilers, which type I dont know yet but the split ones look good!
They are calling for an AUW of the glider at 8lbs or 128 oz
Adam
Hi Adam,

Glad you liked the pix. Not to push to hard, but the Top and Bottom spoilers are the way to go. Move the hinge point back about 2 from the spar, as you do not want to cut into the spar for linkage. Also, reduce the length by one rib bay. Do this at the inside of the spoilers, which moves the vortex away from the stab.

.

Motors:

AUW 8 lbs as glider, less one for lead, add one for Motor, GB, prop and we are back to 8. Add 2 lbs for 16 *2000 SCR Sanyo cells. Now we are at 10 lbs. At 35 watts per pound, we need 350 watts. 16 volts at 22 amps for about a 6(-) minute motor run. (Start at 16 cells, but you can also run 20 cells at 10.5 lbs, 525 watts (50 watts a pound), 26 amps. Or 10 cells at 9 lbs, 315 watts, 31 amps, 4.5 minute run.)

You can do all of these with a Geared Cobalt 40 (10 turn, not FAI). You get the idea.



Stab to follow

Dave
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Old Apr 27, 2002, 10:44 PM
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Stabs?

Quote:
Originally posted by Adam Neat
Thanks for the input guys;

As for the issue of the stabilizer the plans show a pivot point about midway and the servo connected via a cable to the front.

I can see several options here to keep this from coming apart.
1) Build per the plans and eliminate the cable; mount the servo in the tail and have a direct linkage to the front of the stabilator.
2) Build a non-flying stabilizer with seperate elevators.
3) Built a T tail with a seperate elevator.
4) Do something else?
Adam

Sheez, I think the stabs are all wrong, for the big XC version.

First, by proper design the pivot should be at MAC of the stab, actually a tiny bit in front of MAC. (Not at the leading edge!) If you pivot at the LE, you are asking for a major load on the servo.

Next, a pin behind this pivot point should control the stabs. Why? With the main pivot in the right place, the stabs will follow the wing. With the control behind the pivot, any slop will make soft controls, not flutter.

I think the Sag has too much sweep in the stab to make this work. I also think that dynamic / static balance is a problem. Although it would change the look of the plane, I suggest a proven stab design that does not have these problems. I would also stay with full flying as they trim so well (VS. a fixed tail or T-tail).

How about a Falcon 800 Stab (or similar) scaled up to fit your Sag? Use this and a bell crank.

Happy Landings,
Dave
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Old Apr 28, 2002, 08:54 AM
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Winchester; Ohio
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Ok; As for motor setup Ill probably go with an Aveox F12 for the main reason that I already have it. I had to steal it out of my Magic sport plane but sacrifices happen
Ive been putting the numbers in Motocalc and from the motors I have it looks to be the most reasonable choice.

Ill try to get a couple images of the stab and associated hardware and post them. I had always thought that any fully moving control surface needed to pivot at the cg of the surface itself. Similar to Daves statement about the sweep/pivot point not making for a balanced setup.
Adam
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Old Apr 28, 2002, 10:28 AM
allergic to castrol oil
ontario canada
Joined Jan 2002
143 Posts
bellcrank

use a bellcrank and a strong servo,keep in mind that ;its wasnt that the sagitta performed better than most in its class,it was its sweet handling .
if i was you i would question the effects of prop wash on the flying stab
i have flown a similiar plane and found that under power the stab responce was very slow,i believe the stab was directly in the wash [shook the stabs loose]
it seems a shame to alter the design but maybe its needed,i would hesitate changing anything if its not needed,i would hate to loose the flight charateristics of the sagitta because in my oppion thats what made the xc so sweet!

ramair

hey adam, i know you have heard me say that before but really ask around,,its like the old paragon,,its not perfect,but its hard to improve on,many have tried!! thermals by itself!!!!
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