Author Topic: 2012 Stunter - Thundervolt - A Build LOG (Read 22099 times)

Crist Rigotti · « **on:** September 29, 2011, 01:48:28 PM »

Here's my winter build project. I'll do a build log on it.
WS: 55.5 in.
WA: 585 sq in.
A/R: 5.23
Est WT: 50 oz.
Tail Volume: 28%
Motor: Scorpion SII-3020-710kv
ESC: ICE Lite 50
Battery: TP 5S 2700mah ProLite

Edited to note final selection on motor and added weight and balance sheet. 12/21/2011

Bill Ervin · « **Reply #1 on:** September 29, 2011, 02:21:50 PM »

Nice Crist, picked out a name for it yet?

Crist Rigotti · « **Reply #2 on:** September 29, 2011, 02:53:14 PM »

Quote from: Bill Ervin on September 29, 2011, 02:21:50 PM

Nice Crist, picked out a name for it yet?

I'll paint it up like the Thunderbirds. How about Thundervolt?

Howard Rush · « **Reply #3 on:** September 29, 2011, 03:24:50 PM »

Planes like that are out of fashion now. You gotta keep up with the times, Crist. Maybe read GQ.

Bill Ervin · « **Reply #4 on:** September 29, 2011, 04:07:38 PM »

That's it Crist, you nailed it, that's the definitive name.

Crist Rigotti · « **Reply #5 on:** September 29, 2011, 04:20:33 PM »

Quote from: Howard Rush on September 29, 2011, 03:24:50 PM

Planes like that are out of fashion now. You gotta keep up with the times, Crist. Maybe read GQ.

Yeah, I know. I'm a year late huh?

James Mills · « **Reply #6 on:** September 29, 2011, 05:59:48 PM »

Crist,

Sweet, I like the jet look. Good talking with you last weekend, thanks for the wood again.

James

Neal Beekman · « **Reply #7 on:** September 29, 2011, 06:07:23 PM »

My 2012 Stunter will be an Electric ARF Nobler. :)Flew it today3/12/2012 for 2 flight's and 2 minutes each flight , needs a little trim but has enough power and the ballance seems wright.

Dan Bregar · « **Reply #8 on:** September 29, 2011, 07:03:33 PM »

Crist

Is that motor a 3020 size or a 3026 size ? Can't find that P/N ?

Dean Pappas · « **Reply #9 on:** September 29, 2011, 07:46:08 PM »

Mongo like!

Dean

Crist Rigotti · « **Reply #10 on:** September 29, 2011, 08:11:19 PM »

Quote from: Dan Bregar on September 29, 2011, 07:03:33 PM

Crist

Is that motor a 3020 size or a 3026 size ? Can't find that P/N ?

Dan,
The plane will be built to take either the 3020 or 3026 size motors. The p/n for the 3026 is SII-3026-710. If I am to use the 3020 size motor I'll have to have one wound specially for 710kv. I'm exploring other motors.

Dan Bregar · « **Reply #11 on:** September 30, 2011, 04:12:24 PM »

Crist

Won't the 3020 780kv version work ? Does it have to be 710 ? Not much difference, No ? $:-\$

Crist Rigotti · « **Reply #12 on:** September 30, 2011, 04:38:46 PM »

Quote from: Dan Bregar on September 30, 2011, 04:12:24 PM

Crist

Won't the 3020 780kv version work ? Does it have to be 710 ? Not much difference, No ? $:-\$

The 780 should work. At 9800 RPM the 710 is at 75% max rpm, while the 780 is at 68% max rpm. Don't know what running at 68% compared to 75% will do.

Anybody want to weigh in?

Dan Bregar · « **Reply #13 on:** September 30, 2011, 05:17:42 PM »

Crist

I am a novice at this E-Stunt deal, but I think the 3026 mtr. is too much mtr.. The reason your post caught my attention is because I looking to build a similar size airplane (a profile) and was going to use the 3020 mtr.. And mine would probably weigh more than your projected weight. I'm sure someone will post info (Dennis are you out there ?), and help us both out.

Dan

Crist Rigotti · « **Reply #14 on:** September 30, 2011, 07:35:31 PM »

Quote from: Dan Bregar on September 30, 2011, 05:17:42 PM

Crist

I am a novice at this E-Stunt deal, but I think the 3026 mtr. is too much mtr.. The reason your post caught my attention is because I looking to build a similar size airplane (a profile) and was going to use the 3020 mtr.. And mine would probably weigh more than your projected weight. I'm sure someone will post info (Dennis are you out there ?), and help us both out.

Dan

A 3026 motor would be too much, unless I need the weight.

Dan Bregar · « **Reply #15 on:** October 01, 2011, 06:12:53 AM »

Weight ? That's what cast iron props are for !

PerttiMe · « **Reply #16 on:** October 01, 2011, 06:30:09 AM »

Quote from: Howard Rush on September 29, 2011, 03:24:50 PM

Planes like that are out of fashion now....

Fashions come and go. This one is a couple of years ahead of its time

Dean Pappas · « **Reply #17 on:** October 01, 2011, 11:42:01 AM »

Quote from: Crist Rigotti on September 30, 2011, 04:38:46 PM

The 780 should work. At 9800 RPM the 710 is at 75% max rpm, while the 780 is at 68% max rpm. Don't know what running at 68% compared to 75% will do.

Anybody want to weigh in?

Hi All,
A teeny bit more heat and better (faster) governing due to the additional voltage overhead.
As long as you aren't borderline over-stressing the motor to start with ... go for it.

Dean

Crist Rigotti · « **Reply #18 on:** October 01, 2011, 12:29:24 PM »

Quote from: Dean Pappas on October 01, 2011, 11:42:01 AM

Hi All,
A teeny bit more heat and better (faster) governing due to the additional voltage overhead.
As long as you aren't borderline over-stressing the motor to start with ... go for it.

Dean

Dean,
Thanks for the short concise answer! Looks like a good motor to use on a 5S set up!

Crist Rigotti · « **Reply #19 on:** October 01, 2011, 08:01:22 PM »

Day 1 of cutting balsa. It is October 1st. My building season has begun. Flying season isn't over, but building season has started. I plan on redoing the plans in post #1 so they show up better and they have a lot of details added. Enough added that I can start building.

I started on the stab because it is fairly easy and can be built in an evening. Also, I have to get back into working with balsa so the stab it is.

The stab LE, TE, and tips are made up from 3/16 and 1/32 9# balsa. 9# balsa was chosen because it will provide some additional stiffness. I added some unidirectional CF to the LE and TE for stiffness. It is .007 thick. The cross members are from 8# 3/32 balsa. The sheeting is 6.5# .077 balsa. The tips are faced with 1/32 basswood to provide a nice clean durable edge.

The TE is laminated using 2 pieces of 3/16 balsa and 1 piece of 1/32 balsa to form the hinge pocket. The 1/32 is skipped wherever a hinge is to be located. My hinges are exactly centered using this method. Another benefit is that almost from the beginning, my hinge slots are done! After sanding smooth the total width will be slightly over 3/8 thick.

As the stab sits right now it is sanded smooth but the LE and TE have to be rounded. It weighs 47 grams. Add about 14 grams for the Monokote and 8 grams for the elevator horn the total is 69 grams. I budgeted 60 grams. Rounding the LE and TE and final sanding will get me within 4 or 5 grams of budget.

Allen Brickhaus · « **Reply #20 on:** October 01, 2011, 08:58:57 PM »

I like it, keep building.

Allen Brickhaus

Crist Rigotti · « **Reply #21 on:** October 01, 2011, 09:54:55 PM »

The fin and rudder are next.

I used 3/32 7# balsa and 10# 1/32 balsa to make the fin and rudder. As usual, the 1/32 is cut out to form the hinge slot. The grain is different to the sides to form a "plywood" assembly. I used slow setting epoxy for both of these assemblies becuase it gives me more time to work. The epoxy also helps "stabilize" the assembly. I use 3/4 masking tape to prevent the epoxy getting into the hinge slot.

Crist Rigotti · « **Reply #22 on:** October 02, 2011, 08:46:07 AM »

The fin and rudder are finished except for rounding and final sanding. They came out nice and stiff. Shouldn't be any warping when the finish is applied.

The fin weighs 15 grams and the rudder 3 grams. After rounding and final sanding, then trimming the bottom of the fin to match the fuselage top, I think I'll be right on budget of 20 grams for both.

I took a picture to show the hinge slots in the fin and rudder.

Dennis Vander Kuur · « **Reply #23 on:** October 02, 2011, 10:04:33 AM »

Crist,
Great stuff. Keep it coming.

DennisV

Dan Bregar · « **Reply #24 on:** October 02, 2011, 11:08:48 AM »

Crist

Very nice work. I like your method for the hinges. Never thought of it. Way to go Sir !

Crist Rigotti · « **Reply #25 on:** October 02, 2011, 04:24:45 PM »

The flaps and elevators are next. They will be made up of 3/16 sheet and 1/32 balsa.

The elevators are made up of 6# 3/16 balsa and 10# 1/32 balsa. The same method is used as the fin and rudder. The hinge slots are masked off to prevent epoxy getting into the hinge slot. After spreading on the epoxy, the masking tape is removed and the sheets are assembled, weighted and left to dry overnight. The hinge slot is left as "pure" wood. The hinges are 1/32 thick (Klett) and this way the only thing in the slot is the hinge.

The flaps are made up just like the elevators. I used 7# 3/16 and 10# 1/32 balsa for their make up.

After they are made, I'll taper them using the rod method from 3/8 to 3/32.

Crist Rigotti · « **Reply #26 on:** October 02, 2011, 06:57:40 PM »

I thought I'd show what I use to spread out the epoxy. It is a piece of 1/16 birch ply. The corners are rounded to prevent gouging the balsa. The notches are about 1/32 deep about every 1/8 to 3/16 inch.

Allan Perret · « **Reply #27 on:** October 02, 2011, 07:16:24 PM »

Quote from: Crist Rigotti on October 02, 2011, 04:24:45 PM

The flaps and elevators are next. They will be made up of 3/16 sheet and 1/32 balsa.

The elevators are made up of 6# 3/16 balsa and 10# 1/32 balsa. The same method is used as the fin and rudder. The hinge slots are masked off to prevent epoxy getting into the hinge slot. After spreading on the epoxy, the masking tape is removed and the sheets are assembled, weighted and left to dry overnight. The hinge slot is left as "pure" wood. The hinges are 1/32 thick (Klett) and this way the only thing in the slot is the hinge.

The flaps are made up just like the elevators. I used 7# 3/16 and 10# 1/32 balsa for their make up.

After they are made, I'll taper them using the rod method from 3/8 to 3/32.

I use this same method to make hinge pockets for flaps and elevators, but I like to put the 1/32 center lamination across the grain of the two other sheets.

Crist Rigotti · « **Reply #28 on:** October 02, 2011, 07:33:50 PM »

Quote from: Allan Perret on October 02, 2011, 07:16:24 PM

I use this same method to make hinge pockets for flaps and elevators, but I like to put the 1/32 center lamination across the grain of the two other sheets.

Allan,
For the flaps and elevators I have the grain parallel with the TE on the 3/16 sheets and the grain running parallel with the LE on the 1/32 sheet. This way I do get some cross grain. Never had a problem with this method.

Your method would give true crossgrain construction.

Jason Greer · « **Reply #29 on:** October 02, 2011, 08:12:38 PM »

Crist,

Great build thread. I'll definitely be using some of these ideas in the future.

Thanks for taking the time to take detailed pictures and post your progress.

Jason

Crist Rigotti · « **Reply #30 on:** October 03, 2011, 09:17:57 PM »

Not much got done tonight. I took the weights off the flaps and elevators. Nice and stiff, but a bit heavy. I'll continue to build them and when done, I'll weight them and see what I'll do.

The pictures show how I locate the elevator control horn and clips. I cut out some 1/32 plywood 3/4 wide x 1 1/2 long. I use them to locate the elevator to the TE. I mark on the TE where the horn is to be located. This location is usually not quite centered. I place the horn with the clips at this mark and mark the elevators. After marking, I use a right triangle to mark the elevator where the clip is supposed to go. This makes the clip 90 degrees to the LE. While I'm at it, I mark the tips too.

I cut the elevator and sand it to the line previously made. I put the elevators back on the stab using the 1/32 plywood tabs and do a check fit of the horn and its clips. Once good, glue on the clips making sure they are centered on the elevator. I'll do this tomorrow.

john e. holliday · « **Reply #31 on:** October 06, 2011, 09:10:03 AM »

I like the new build. May have to try them sometime if I can remember.

Crist Rigotti · « **Reply #32 on:** October 09, 2011, 07:21:22 PM »

I have been out of town lately but now have the elevators "blocked" out. I have installed the elevator horn clips, sized and edged the elevators with 1/32 basswood. The one picture shows the "pocket" that I build into the root of the RH elevator for the Rabe rudder linkage.

Bill Little · « **Reply #33 on:** October 10, 2011, 12:05:13 AM »

Looking great so far, Crist! I especially like the various tips you are including with the build.

Bill

Tom Niebuhr · « **Reply #34 on:** October 10, 2011, 07:57:44 AM »

Crist,
Great build.

Howard said: "Planes like that are out of fashion now. You gotta keep up with the times, Crist. Maybe read GQ."

There is no longer an "In Fashion" style. For once, just about anything goes. The electrics will be opening new doors. This is a wonderful time for entry of new airplane designs with nostalgia, racing, scale like, jet, twins, retracts, wider more realistic fuselages, futuristic styling , and more. People are also realizing that the bias for or against certain styles have for the most part disappeared. While the "Classic Era" could be considered the Golden Age" of stunt, we are now entering the "Platinum Age" of stunt design. This is exciting.

Dennis Adamisin · « **Reply #35 on:** October 14, 2011, 06:48:08 PM »

ANothe great project and build thread. THANKS for all the pix and commentary.

Crist Rigotti · « **Reply #36 on:** October 17, 2011, 07:38:08 PM »

Thanks Bill, Tom, and Dennis.

On to finishing the elevators. I'm using tapered elevators on this model and after reading the thread about tapered flaps in the building section, I decided to use the "Perret Bar" method.

This method works slick, but you must be careful to set everything up correctly. Thank you Allan! I didn't have any 1/4 aluminum bar stock but had some 1/8 which I used. For the front rod I used some 3/8 diameter steel with 1/32 ply epoxied to the "bottom" of the rod every so often. I did this to stabilize the rod and also a way to "adjust" the height. I added 4 layers of masking tape to the bottom of the 1/32 ply to get it to the correct height. Sanding in the taper was easy and I did the top on both elevators, then readjusted the bars and sanded the bottom taper on both elevators. This assured that both elevators would be tapered the same.

After sanding the LE round, I sanded in the hinge barrel pockets. I use a tool that I made from some 1/2 balsa, 1/8 lite ply and a piece of 1/16 plywood. I used the masking tape to adjust the depth of the "pocket" to match the Klett hinges that I'm using.

I then rounded the LE and TE of the stabilizer. I like rounded TE's of the wing/stabilizer and rounded LE's of flaps/elevators. I believe that it promotes a smoother airflow from the wing/stabilizer to the flap/elevator.

Between the stabilizer, elevator horn, and elevator I'm over budget by 12 grams. I'm going with the stabilizer and we'll see what I do with the elevators. I have to see after I build the wing and fuselage then decide if I keep them solid or if I hollow them and install "ribs" to lighten them.

wwwarbird · « **Reply #37 on:** October 17, 2011, 11:13:09 PM »

Quote from: Crist Rigotti on September 29, 2011, 02:53:14 PM

I'll paint it up like the Thunderbirds. How about Thundervolt?

So Crist, you're gonna have a red white and blue plane now?

Allan Perret · « **Reply #38 on:** October 18, 2011, 03:02:33 PM »

Quote from: Crist Rigotti on October 17, 2011, 07:38:08 PM

I'm using tapered elevators on this model and after reading the thread about tapered flaps in the building section, I decided to use the "Perret Bar" method.
This method works slick, but you must be careful to set everything up correctly. Thank you Allan! I didn't have any 1/4 aluminum bar stock but had some 1/8 which I used. For the front rod I used some 3/8 diameter steel with 1/32 ply epoxied to the "bottom" of the rod every so often. I did this to stabilize the rod and also a way to "adjust" the height. I added 4 layers of masking tape to the bottom of the 1/32 ply to get it to the correct height.

Fantastic, glad to see you use my method. Even gave it a name. I used a combination of 1/4" and 1/8" aluminum bars, thats what I had on hand at the time. You do have to be finicky with the setup. You can do it by eyeball if you are real accurate with the centerline marking. Another way would be calculate the bar heights and them make a step guage reference for setting them. For LE sanding stop I use either hard wood or even hard balsa square section. Before start sanding use black marker to make it black. Now as soon as you sand down to the stop you will know, as you cut into the black layer. I put piece of tape on the aluminum stops for same purpose.
Great looking build Crist, keep it going.

Crist Rigotti · « **Reply #39 on:** October 18, 2011, 09:25:05 PM »

Quote from: Allan Perret on October 18, 2011, 03:02:33 PM

Fantastic, glad to see you use my method. Even gave it a name. I used a combination of 1/4" and 1/8" aluminum bars, thats what I had on hand at the time. You do have to be finicky with the setup. You can do it by eyeball if you are real accurate with the centerline marking. Another way would be calculate the bar heights and them make a step guage reference for setting them. For LE sanding stop I use either hard wood or even hard balsa square section. Before start sanding use black marker to make it black. Now as soon as you sand down to the stop you will know, as you cut into the black layer. I put piece of tape on the aluminum stops for same purpose.
Great looking build Crist, keep it going.

Allan,
I was thinking of making some step gauges! I saw in your photos that you used a magic marker on the hardwood LE stop. Good idea. I used masking tape on the TE bars too!

Crist Rigotti · « **Reply #40 on:** October 18, 2011, 09:25:45 PM »

Quote from: wwwarbird on October 17, 2011, 11:13:09 PM

So Crist, you're gonna have a red white and blue plane now?

Yup, just like always.

Crist Rigotti · « **Reply #41 on:** October 18, 2011, 09:35:32 PM »

On to the wing. I'm using Bob Hunt's Lost Foam Wing construction. I made my own jig seeing I can cut foam.

I made a drawing of the wing planform with all the rib and spar lines extended so it would be easier to mark their locarion on the foam. I cut out the blanks, both being equal. In reality the wing has 1/2 inch offset to it, but the jig halves will be identical except for the RH tip rib location. Traced the rib and spar locations on them. Located a center line around the perimeter, and cut the cores. Sanded the flash off and then trued the bottom halves to be equal so I don't build in a warp. Then glued them with some 30 minute epoxy. I used some masking tape in 'tension" to hold them together. I then sanded and rounded the LE of the cores.

Crist Rigotti · « **Reply #42 on:** October 19, 2011, 09:10:39 PM »

Tonight I continued to work on the LF jig. I drew the spar, ribs, and TE locations on the foam. I also cut out each section of foam. Next I'll sand and add the glue to the edges of the sections in preparation to cutting out and shaping the ribs. I'll also cut out a LE buck in the next day or 2.

Crist Rigotti · « **Reply #43 on:** October 24, 2011, 08:35:53 PM »

Back on the LF jig. I rubbed carpenters glue along the edges of the foam to strengthen the foam against sanding the ribs to shape. The LE buck is next.

Bill Ervin · « **Reply #44 on:** October 25, 2011, 09:19:20 AM »

A big thanks for showing the foam work Crist! How do/did you section the core while leaving the beds intact?

Crist Rigotti · « **Reply #45 on:** October 25, 2011, 10:58:42 AM »

Quote from: Bill Ervin on October 25, 2011, 09:19:20 AM

A big thanks for showing the foam work Crist! How do/did you section the core while leaving the beds intact?

Bill,
I used the top as the bottom bed when doing the sectioning.

Paul Walker · « **Reply #46 on:** October 25, 2011, 03:18:51 PM »

Howard said: "Planes like that are out of fashion now. You gotta keep up with the times, Crist. Maybe read GQ."

There is no longer an "In Fashion" style. For once, just about anything goes. The electrics will be opening new doors. This is a wonderful time for entry of new airplane designs with nostalgia, racing, scale like, jet, twins, retracts, wider more realistic fuselages, futuristic styling , and more. People are also realizing that the bias for or against certain styles have for the most part disappeared. While the "Classic Era" could be considered the Golden Age" of stunt, we are now entering the "Platinum Age" of stunt design. This is exciting.

Tom,
That was an inside joke from Howard. Crist's new plane looks like the little brother of the plane I have been flying for the last 2 years. Next years planes will have a different shape, thus Howard's comment.

Paul Walker

Crist Rigotti · « **Reply #47 on:** October 26, 2011, 08:08:48 PM »

Tonight I made the LE buck. The plywood base is from some unused wood flooring left over from a remodel.

Crist Rigotti · « **Reply #48 on:** October 29, 2011, 07:37:45 AM »

Last night I discovered that I made a mistake when doing the CAD drawings of the wing. I was measuring the LE buck for the width of the sheeting and the tip width seemed to be almost as wide as the root. I also noticed that the spar location was well aft of the high point. I went to my drawing program and looked at the tip rib profile and the spars were located at the high point. I checked my top view of the wing and I had the spars nearly 3/4 inch further aft! I then corrected the drawing so at least that is correct now. Glad I caught it now!

I can draw the correct spar location on the bottom of the LF jig easily. I'm thinking about the spar locations that was drawn on each rib section and how to get them correct. I was thinking of just cutting out the ribs without the spar locations. Then setting them in place in the LF jig, then marking the bottom spar locations. Turn the ribs over and mark the top spar locations. Then proceed as normal with construction.

I've included a pictue of the LE buck and now that I look at it, it doesn't have much taper between the root and the tip. Also a picture of the LF jig tip that shows an pretty far aft spar location.

Crist Rigotti · « **Reply #49 on:** October 30, 2011, 09:31:28 PM »

An update on the spar relocation. I drew the correct location of the spars at the tips (5/8 fwd). I then made a rib and located the bottom spar cutout using the bottom of LF jig. I then flipped over the rib and located the top spar. This worked out well.
I'll have to put this project aside for a couple of weeks. I'll be back mid November.