First Build in Three Years

[Crist Rigotti]

    Holy cow, put an FP or LA on it and go have a blast. 

How long can you hold your breath.  Hope you and the gang are doing well.

[Avaiojet]

I built a Walter Umland Sakitumi over the last month.  First stunter I've built in 3 years.  Looks like the weather will cooperate this Saturday for first flight.
Some stats:
Wing span: 55.5"
Wing area: 621 sq/in
Weight: 45 1/2 ounces with battery ready to fly
Solid and transparent Monokote used
Bad Ass 3515-710 motor
Spin 44 esc
Igor's active timer
Dinogy 6S 1800mah battery which weighs 260 grams.

Some mods I did was to move the canopy forward, lengthen the nose about an inch, and added a little more sweepback to the fin trailing edge.  Made the fuselage 3/4 inch wide.

Crist,

Thank you for igniting my interest in the BadAss motors. I took a look at their offerings. They have plenty of information on their website, text and drawings.

You selected the 3515 and I'm curious as to why? Unless my findings are incorrect, the 2826 would also do the task. You're model is light, really light. Also a 4cell 3300 may be a bit lighter unless you needed the nose weight for balance? Is the 2826 and a 4 cell 3300 a good match?

My Stuka is at 49 oz and I believe the 2826 can do the trick, unless I missed something, which is my question.

Did I miss something?

Charles

[Crist Rigotti]

Crist,

Thank you for igniting my interest in the BadAss motors. I took a look at their offerings. They have plenty of information on their website, text and drawings.

You selected the 3515 and I'm curious as to why? Unless my findings are incorrect, the 2826 would also do the task. You're model is light, really light. Also a 4cell 3300 may be a bit lighter unless you needed the nose weight for balance? Is the 2826 and a 4 cell 3300 a good match?

My Stuka is at 49 oz and I believe the 2826 can do the trick, unless I missed something, which is my question.

Did I miss something?

Charles

Charles,
I chose the 3515 because that is what I'm currently running in my other profile and my full fuse stunt ship, both around 580 sq/in.  The reason I'm running a 3515 in my full fuselage stunt ship is that I found here in the Dallas heat, the 2826 was running a little too hot.  BTW, a characteristic is that they just run hotter than the 35mm motors.  So I'm running a 3515 Cobra or BA is that simply they run cooler than a 2826.  Yes, a 2826 or even smaller will/might do for the Sakitumi.  Since all my models use a 35mm motor, it is easy to use a component from another ship if I have to.

According to my ECL spreadsheet a 46 oz airplane with a motor run for 5.4 minutes:
3S = 3650mah battery
4S = 2700mah battery
5S = 2200mah battery
6S = 1800mah battery

[Avaiojet]

Charles,
I chose the 3515 because that is what I'm currently running in my other profile and my full fuse stunt ship, both around 580 sq/in.  The reason I'm running a 3515 in my full fuselage stunt ship is that I found here in the Dallas heat, the 2826 was running a little too hot.  BTW, a characteristic is that they just run hotter than the 35mm motors.  So I'm running a 3515 Cobra or BA is that simply they run cooler than a 2826.  Yes, a 2826 or even smaller will/might do for the Sakitumi.  Since all my models use a 35mm motor, it is easy to use a component from another ship if I have to.

According to my ECL spreadsheet a 46 oz airplane with a motor run for 5.4 minutes:
3S = 3650mah battery
4S = 2700mah battery
5S = 2200mah battery
6S = 1800mah battery

Crist,

What a guy!! Thanks for the information and reply. 

Will you be leaning towards the Cobra in the future with other purchases or the BA?

Thanks again.

Charles

[Crist Rigotti]

Crist,

What a guy!! Thanks for the information and reply. 

Will you be leaning towards the Cobra in the future with other purchases or the BA?

Thanks again.

Charles

Let me run the BA for awhile before I answer that.

[Crist Rigotti]

Here's an update after 2 more flying sessions.

I used a heat gun to slightly twist the wing to get the wings level.  And I mean slightly.
I had 3/4 oz tip weight to start with and removed 1/4 oz.  Much better.

Fabricated a new elevator horn.  The old horn had the holes lined up with the hinge line but was not 90 degrees to the push rod.  So it gave me more down than up.  Made a new horn that is 90 degrees to the push rod and has the holes lined up with the hinge line. 

Went with a 11 1/2 inch prop instead of 12 inches.  Battery draw after a 5 1/2 minute flight is anywhere from 1400 to 1450mah.  Or 78 to 80%.

Still has the 2 ounces of nose weight.  New batteries have been ordered.

The airplane is flying decent now with only 1 exception.  And the is the 3rd corner of the Hourglass.  The outboard wing drops during the corner.  It drops enough so I can see the bottom of the outboard wing.  Even when I go easy on that corner it still drops, not as much when I hit hard , but still drops.  Everywhere else in the pattern the airplane handles well.  Any ideas as to the cause and fix would be appreciated.

The overall thoughts are it is a very good flying airplane with a very nice corner.  Unfortunately, it suffers the fact that in a nice square corner, it does not want to stop turning.  A common problem with flapless stunters.  I found myself overturning most square corners because of this.