First Build in Three Years

[Crist Rigotti]

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.

[Fred Underwood]

Looks great!  I assume that this the plane that you are talking about on the line length thread.

How about a few more shots of the nose with some detail on battery and electronics installation.  How/where is the active timer/sensor?

[Crist Rigotti]

How's this:

[wwwarbird]

 Looks great Crist!

[Brett Buck]

How's this:

   Looks great!  So, question, have you tried replacing the JJ 12AX7s in the motor controller output amp stage with NOS Telefunken ECC-83s? Howard says it works about the same, but the pre-launch beeps are much more engaging and not nearly as gritty. 

    Brett

[Will Hinton]

Hi Crist!  Good to see you re-engaged with it.  I hope you're all well and safe, love to seeya sometime.
Will

[Allen Goff]

Very nicely done Crist, hope to see you and it in the circle sometime somewhere.
Blessings
Allen

[Crist Rigotti]

Hi Crist!  Good to see you re-engaged with it.  I hope you're all well and safe, love to seeya sometime.
Will

Thanks Will.  I'm planning on making the NATS, and of course FCM along with some other Midwest contests.
We are all well and safe.  All the best.

[Crist Rigotti]

Very nicely done Crist, hope to see you and it in the circle sometime somewhere.
Blessings
Allen

Thanks Allen.  We'll see you at the NATS and FCM for sure.

[Crist Rigotti]

   Looks great!  So, question, have you tried replacing the JJ 12AX7s in the motor controller output amp stage with NOS Telefunken ECC-83s? Howard says it works about the same, but the pre-launch beeps are much more engaging and not nearly as gritty. 

    Brett

I'll leave that mod up to Howard!  Though I do miss the glow from those 12AX7's!

[Fred Underwood]

Crist, very tidy electronics with the shortened leads and the direct plug into the ESC, like your previous.  Do you expect any difficult is leveling/keeping level the sensor?  It looks secure enough on your super grip.

A reverse pitch prop if I see correctly? What pitch and what rpm range are you aiming for?  Yes, that will be line length dependent, so maybe Brett will re-engage and help.

[James Mills]

Looks nice Crist, hope to see it at a contest this year.

James

[Crist Rigotti]

Crist, very tidy electronics with the shortened leads and the direct plug into the ESC, like your previous.  Do you expect any difficult is leveling/keeping level the sensor?  It looks secure enough on your super grip.

A reverse pitch prop if I see correctly? What pitch and what rpm range are you aiming for?  Yes, that will be line length dependent, so maybe Brett will re-engage and help.

I don't expect any difficulty at all.

Yes reverse pitch prop...for now.  I have a special tractor prop I'm going to try once it gets trimmed out.  Right now it has a APC 13x5.5EP cut down to 12 inches.

[Crist Rigotti]

Looks nice Crist, hope to see it at a contest this year.

James

Thanks James.  Maybe next month in St. Louis!

[Stuntflyn]

Hi Crist,

Long time no see. I love your Sakitumi, it is a surprisingly good flying airplane, I am sure you are going to like it. With all the Igor stuff in there, it should be awesome.

Wayne and I built one about 5 years ago (I've attached a photo below), the only real change we had to make was to the elevator control horn. The one in the kit was average in length and the control response was off the chain. We ended up using a radio control aileron horn that we could screw up and down to find just the right length. I'm not sure why it was like that, it might have been tail heavy, we were running a 5S 3300 MaH battery in the front, but it is a short nose and it was before we knew to move the CG forward for electric, so maybe it was tail heavy. Tail heavy or not, once we got the long horn on there, it was a pretty awesome flyer.

We went to Joe Nall a few years back and we both flew the Sakitumi. We also talked Derek Barry into flying it in profile as well. That dirty dog ended up beating both Wayne and I with our own plane. Hah . . . it was great fun.

We ended up dorking it somewhere - don't even remember why, not too bad, so we gave it to Will Davis who fixed it up and is flying it still to the best of my knowledge.

I hope you have a lot of fun with it and will look forward to hearing how it flies - Jim Smith

[Crist Rigotti]

Hi Jim,
Thanks for the kind words.  My CG is at 20%.  about 1/2 inch aft of the plans CG at 15%.  I'm using an aluminum elevator horn with the push rod set at 1".  The bell crank end is at 3/4" per plan.  It does seem to have a lot of elevator throw.  I'll fly it tomorrow for the first time so we'll see.

Yeah, I hate to get beat by my own airplane too!  Reminds me of a story.  During one of the NATS that Paul Walker was the ED, I had entered my profile electric airplane.  After it was over Paul asked if he could fly it.  He did a nearly 40 point take off and during the first pullout of the RWO, he said "Oh", and then proceeded to put up the best flight that airplane ever did by a wide margin!  At least a 500 pointer!  So good my buddies said that that would be the best flight the airplane will ever fly!  They were right.

[John Rist]

Love you color scheme on your Sakitumi.  I see you followed the unwritten rule that you must use transparent film on a Sakitumi wing to show it great internal rib structure.   

[Crist Rigotti]

Love you color scheme on your Sakitumi.  I see you followed the unwritten rule that you must use transparent film on a Sakitumi wing to show it great internal rib structure.   

Yeah, I saved about 3/4 ounce over solid color Monokote!

[John Paris]

Crist,
What are you using to hold your sensor in place under the wing?  Nice looking airplane.
Thank you,
John

[Dane Martin]

Yeah, I saved about 3/4 ounce over solid color Monokote!

It's wild what a weight difference the solid colors vs transparent colors have!

[Crist Rigotti]

Crist,
What are you using to hold your sensor in place under the wing?  Nice looking airplane.
Thank you,
John

3M Dual Lock

[Crist Rigotti]

It's wild what a weight difference the solid colors vs transparent colors have!

 

[Tom Luciano]

Nice looking ship, Christ!

Best of luck with it.
Tom

[Crist Rigotti]

Thanks Tom.

[Dennis Vander Kuur]

Crist,
I see the master craftsman has created another beautiful airplane. It looks great! Congratulations.
Looking forward to seeing you this summer and getting in some "friendly" flying competition(and lie swapping) 
Best regards,
DennisV

[Neal Beekman]

What battery are you using? Very nice and neat.

[Warren Walker]

Sanitary is the only word I can think of.
great job.

[Joseph Daly]

Christ,
Very nice looking ship!
Thanks
Joe

[Crist Rigotti]

Crist,
I see the master craftsman has created another beautiful airplane. It looks great! Congratulations.
Looking forward to seeing you this summer and getting in some "friendly" flying competition(and lie swapping) 
Best regards,
DennisV

Thanks Dennis.  Yeah, I'd like to get in some "friendly" competition and lie swapping for sure. 

[Crist Rigotti]

What battery are you using? Very nice and neat.

Dinogy 6S 1800mah

[Crist Rigotti]

Sanitary is the only word I can think of.
great job.

Thanks Warren.

[Crist Rigotti]

Thanks Joe.  See you at the NATS?

[Joseph Daly]

Crist,
Yes we will be at the NATS!
Joe

[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,

Really nice job and incredible low weight. Congratulations.

Is the Jeti spin 44 going to get you through the pattern? I know it's half the weight of the 66.

I went on line and eyeballed the Badass offerings. Stuff looks great! So, good choice.

Good luck with your new model.

Charles

[Mike Scholtes]

There's just something about trans red monokote ,,,

This is the .25 Saki but the same "trans monokote" rule applies. These are great flyers at any size, you will have a ball with yours. Needs a hollow Igor 3-blade though.

[Steve Fitton]

Looks awesome Crist!

[Crist Rigotti]

Crist,

Really nice job and incredible low weight. Congratulations.

Is the Jeti spin 44 going to get you through the pattern? I know it's half the weight of the 66.

I went on line and eyeballed the Badass offerings. Stuff looks great! So, good choice.

Good luck with your new model.

Charles

Thanks Charles.  The Spin 44 is plenty of ESC for the weight of the model.  My average current is about 16 amps.

[Crist Rigotti]

There's just something about trans red monokote ,,,

This is the .25 Saki but the same "trans monokote" rule applies. These are great flyers at any size, you will have a ball with yours. Needs a hollow Igor 3-blade though.

Yeah, transparent Monokote rules the Sakitumi's!
Not so sure I want to spend that kind of money on a prop....yet.

[Crist Rigotti]

Looks awesome Crist!

Thanks Steve.

[Crist Rigotti]

I flew it this morning.  After getting the lap speed to 5.2 on 62 foot line eye to eye and the handle neutral, I started to see what it can do. 

The model is tail heavy at 20% CG.  I added about 1 1/2 ounces to the nose and it was much better. 

The elevator as set up per the plan is way to twitchy for me.  3/4 bellcrank pivot.  My handle line spacing is at the minimum and the elevator push rod is at 1 inch from the hinge line.  There it was much more comfy.  I'll install a longer elevator horn and increase the handle spacing some.  If I were to build another one, I would increase the stab area and decrease the elevator area the same amount and use a 1/2 to 5/8 bell crank pivot for the push rod.

The 6S 1800mah batteries might not cut it in the long run.  After 2 full pattern flights, I put back in 1550mah average between the 2 flights, which is 86% of the battery capacity.  Even with the more efficient BA motor.  Not real happy about that.  I thought that I would use about 1350mah (75%) for a full pattern.  Looking for options right now.

[Stuntflyn]

Hey Crist,

You can easily go to a larger battery since you had to add 1.5 oz to nose anyway, this way that nose weight will at least serve a purpose other than compensating for what could have been designed out. I think someone here asked if you had lengthend the nose, must be someone familiar with the Sakitumi.

Maybe Walter will see this and make a few minor changes. A longer nose would help align the CG  in a better place. We used a 5S 3300 MaH battery and physical space was an issue as well. I can’t remember if Walter makes it as an electric model kit or glow.

I like your idea about changing the stab to elevator ratio. I remember as a kid our Dad started Wayne and I off with Ringmasters (Sterling used to put some gosh awful wood in their kits) and then graduated us to Top Flite Flite Streaks (McCoy Red Head .35). Lol . . . we didn’t get to have Fox .35’s until we could complete the AMA pattern and we wore out those McCoys in one summer.  It always amazed me as an eight year old how the Streak could do any maneuvers with such a little elevator compared to the gigantic one on a Ringmaster.

Keep the flight reports coming. One day maybe I’ll get to see it fly, that would be awesome. Not sure if Wayne and I will attend the Nats this year with the Covid-19 crap still hanging around. I’m not so worried about the folks in Indiana, but the Nats draws people from all over, many from hot spot areas. I know it is likely a small risk, but that virus is no joke for susceptible people, particularly those not aware they are susceptible. Since mass testing is not quite here yet, it is somewhat problematic.

Just waiting to hear what AMA says on June 10th. Not sure I want to be at appearance judging with 100 of my best friends who may not even know they are asymptomatic. We had a young police officer here die from it because he was unaware of a condition he had. Lol . . . I hate the Chinese communists.

[Ken Culbertson]

(McCoy Red Head .35). .....and we wore out those McCoys in one summer.

It took the whole summer?  I used to get about 50 good/great runs after break in which took FOREVER!

Ken

[Crist Rigotti]

Wow! Beautiful ship Crist! Typical of your outstanding workmanship and attention to detail. It is what a model should look like. Very glad to see you back at it.

Brother Bob

Thanks brother!

[Crist Rigotti]

Hey Crist,

You can easily go to a larger battery since you had to add 1.5 oz to nose anyway, this way that nose weight will at least serve a purpose other than compensating for what could have been designed out. I think someone here asked if you had lengthend the nose, must be someone familiar with the Sakitumi.

Maybe Walter will see this and make a few minor changes. A longer nose would help align the CG  in a better place. We used a 5S 3300 MaH battery and physical space was an issue as well. I can’t remember if Walter makes it as an electric model kit or glow.

I like your idea about changing the stab to elevator ratio. I remember as a kid our Dad started Wayne and I off with Ringmasters (Sterling used to put some gosh awful wood in their kits) and then graduated us to Top Flite Flite Streaks (McCoy Red Head .35). Lol . . . we didn’t get to have Fox .35’s until we could complete the AMA pattern and we wore out those McCoys in one summer.  It always amazed me as an eight year old how the Streak could do any maneuvers with such a little elevator compared to the gigantic one on a Ringmaster.

Keep the flight reports coming. One day maybe I’ll get to see it fly, that would be awesome. Not sure if Wayne and I will attend the Nats this year with the Covid-19 crap still hanging around. I’m not so worried about the folks in Indiana, but the Nats draws people from all over, many from hot spot areas. I know it is likely a small risk, but that virus is no joke for susceptible people, particularly those not aware they are susceptible. Since mass testing is not quite here yet, it is somewhat problematic.

Just waiting to hear what AMA says on June 10th. Not sure I want to be at appearance judging with 100 of my best friends who may not even know they are asymptomatic. We had a young police officer here die from it because he was unaware of a condition he had. Lol . . . I hate the Chinese communists.

Yeah, that's the plan I'm looking at.  Going to a 6S 2200mah battery.  The added weight will work out just about right.  The big problem is finding them at a reasonable price.  I like Rhino and Zippy Compact batteries but HK is out of stock right now.  Hyperion is having a good sale on their Graphene HV Lipos but the word is that HV lipos in general don't last very long.  Of course I'll be using them  in the 4.2 volt mode.  Anybody have any experience running HV Lipos in the LV mode?

Next good day of flying looks like Monday.  I did extend the elevator horn to 1 1/4.

[Dane Martin]

Yeah, that's the plan I'm looking at.  Going to a 6S 2200mah battery.  The added weight will work out just about right.  The big problem is finding them at a reasonable price.  I like Rhino and Zippy Compact batteries but HK is out of stock right now.  Hyperion is having a good sale on their Graphene HV Lipos but the word is that HV lipos in general don't last very long.  Of course I'll be using them  in the 4.2 volt mode.  Anybody have any experience running HV Lipos in the LV mode?

Next good day of flying looks like Monday.  I did extend the elevator horn to 1 1/4.

LiHV is a different composition. So if you only charge it to 4.2v per cell, you're not going to get the correct run time. It's the same as only charging your regular batts to 4.0v per cell. I run LiHV batteries all the time in my "other" hobby.
Maybe look into, pyrodrone.com
This one is like 45 bucks. The GNB line is exceptional quality also.
https://pyrodrone.com/collections/batteries/products/pyro-drone-graphene-2200mah-6s-22-25v-75c-by-who-cares

[John Rist]

TP has a 6S 2250.  But at $73 it ain't cheep.  However they do run a sale once in a while.  Unfortunately the PROLITEX SERIES 25C does not come in a 6S. The PROLITEX SERIES 25C seem to be the battery of choice in a 4S setup.

https://www.thunderpowerrc.com/collections/2250-mah-1/products/tp2250-6se55

[Brent Williams]

AliExpress has many 6s2200 batteries for around $35 +/-  https://www.aliexpress.com/w/wholesale-lipo%206s%202200mah.html

Banggood has several offerings as well.  https://usa.banggood.com/URUAV-22_2V-2200mAh-65C-6S-Lipo-Battery-for-RC-Racing-Drone-Helicopter-p-1570517.html?utm_source=googleshopping&utm_medium=cpc_organic&gpla=1&gmcCountry=US&utm_content=shopping&utm_campaign=usg-pc&currency=USD&createTmp=1&utm_source=googleshopping&utm_medium=cpc_bgcs&utm_content=frank&utm_campaign=pla-usg-all-pc&cur_warehouse=CN

[Leester]

Hey Crist: Fantastic looking plane, You and your family Stay safe!!

[wwwarbird]

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

[Crist Rigotti]

Hey Crist: Fantastic looking plane, You and your family Stay safe!!

Thanks Lee. You keep safe too.