KV Ventus 2CX 4.8-meter assembly

[edfmaniac]

I think I have a plan. It appears that I will have enough leverage to keep everything internal by bringing the hinge on the linkage up to the top of the wiper where it just clears the trailing edge of the wing. It will be invisible unless flaps are deployed. The system came with six different servo arms so matching the throw for a very short lever on the control surface won't be an issue.

[Mark9]

Thanks for the kind words Victor. On the Ventus the surface thickness at the horn is .392" to .260", didn't think LDS would give me much of a fulcrum. Besides, a friend told me that it isn't a spot lander and with the air brakes you can control the glide slope very well. Still I achieved all of the goals to maximize servo resolution, torque and throws. The inboard flaps get around 35 degrees of down deflection before mechanical interferences take control.

BTW, started the wiring loom today in the fuselage. All electronics, but the two switches are installed. Tested my separate battery system for the retract servo and it was successful. The only things remaining are essentially extensions, loom dress out, CG and final radio set-up. WHOA, almost time for the roll out!

[edfmaniac]

There was a compromise to keep the linkages internal. By my guesstimations, I don't have enough fulcrum to use the flaps as ailerons beyond the few degrees of up I will need in speed mode. The kit came with a small threaded brass post/horn as an option if you need more length. Hopefully the KST X10's will be as nice as their MKS counterparts in regards to resolution and centering ability. The gear train is very tight and smooth.

I look forward to flying with you in a few more weeks.

[Mark9]

Well I had a set back when I tried to fully run the system assembled. My interconnect wiring from the avionics to the wing was not acceptable to the ground crew. Everything was just too tight and difficult to assemble the airframe, even here in the comfort of the house. They demanded a redesign prior to rollout! The first picture shows the original configuration and the second shows the final configuration at the wing junction.

It now works much better and the third picture shows the final avionics installation. Hated to ditch the original harnesses, but it will be easier to live with! So, with the airframe assembled I began doing some radio set up. Every surface moves the correct way and I have set up some of the mixing already, even spoiler to inboard flaps. Next big step is CG and then graphics for visibility. It will be ready for Apache Pass.

BTW, the two Equalizers are to expand the servo control capability. Since I am using my SD-10G they allow me to control 2 more of the 12 servos for centering and endpoints without upgrading to a new radio. Cannot stand discrete control of each servo being missing. I also added the Power Expander to provide High Voltage direct to all HV servos, plus I can add a second HV battery with a slight modification to my battery tray.

[ARUP]

That sure looks tidy! Two thumbs up!

[Mark9]

OK, so early on I have warned you guys I’m a slow builder/assembler. This morning I hit a major milestone in the process of getting a new airplane ready to fly…the most complex tool I expect to need from now on is a screwdriver other than the Vanessa Rig! YEAH! OOH, forgot my transmitter too (a tool to fly the airplane).

Anyway, my initial CG checks with the Vanessa Rig said I needed 28 oz. of lead to reach the front of the recommended CG range. The first pic shows her in the garage with a bag on her nose full of lead. Not a problem, I expect to add significant nose weight to any glider, but more than I expected. My initial plans were to pour lead shot mixed with epoxy in the nose with the tail in the air. Now how do I get 28 oz. in the nose?

One of ARUP’s posts this last building season made me rethink my original plan, thanks Michael. So, I installed a dam to hold about 19 oz. of lead. Didn’t want a leak locking up my tow release and access for the pull rod might be a major issue if needed later for service.The second shot shows the set up for the pour. I weighed everything I poured in and I think I am very close.

That left 9 more oz. to add in. My adjustable ballast plates next to the tow release shown in the third shot can hold in excess of 12 oz (shown is about 6 oz.). Each plate weighs roughly .5 oz., so I have working room and can easily experiment with CG. That being said I realized why not add a redundant battery. As a result I modified my battery tray to add an additional 2600 mah LiIon battery, which the Battery Expander supports. I now have 5600 mah. of capacity in theory.

The final airplane shot shows the final avionics installation. The third battery is about 3 oz., BTW. It's now ready for final CG and any additional adjustment to the adjustable ballast. Saw the last pic when I walked through the living room one morning of my roommates while working on the Ventus, had to post it. Can’t wait for Apache Pass!

[Mark9]

Sorry, but this got a little wordy and I wanted to complete the effort, but it’s ready to fly! My first use of sign vinyl was educational and in places a little tedious. The results are quite satisfactory considering how quick it is to painting and it can be done with common hobby tools. I wanted to cover the main body of the center section in one piece. That was a challenge since the panel length is 5’. My arm span is less than that! Ended up laying down at the root with part of the backing folded over and all of the panel wet down with the dish detergent and water. Then I rolled it on to the rest of the panel after wetting the newly exposed vinyl with the water dish detergent mix.

That worked well and the squeegee process went well also. Except I have one bump from a piece of FOD in both wing panels, damn OCD. Sorry my house is not a clean room! But, at 15’ you can’t even see it and doubt the airplane will notice either. Also, without a spray booth most likely I would have had more undesirable hickies. I used my sanding technique, described in another thread, to trim the LE after it dried for a while. I had to modify my technique though, the vinyl gummed up the 320 quickly. So, I started with 220 grit.

I used the 220 carefully until the substrate just started to show through the vinyl. Then I used the 320 to smooth up the “cut” and finish removing the drop off. Both of the blocks I used are the maple blocks Airtronics supplied with their sailplane kits back in the day for you old hands (like me). They are light weight and just the right size for accurate work. I found that the dihedral break transition was the most difficult to get right.

The first picture shows the point at which I move to the next section with the 220 grit. In the next one it is how the LE looks “cleaned up” with the 320, hard to see even with the macro setting on my camera. As I said in that other thread, I have a problem cutting straight lines freehand and this method also results in no ledges in the area of the LE. Also, the LE of the wing is the most important section and any turbulence created there will drastically affect the airfoil performance, IMHO. Time consuming, maybe a little yes (the second panel took about 1.5 hrs.once I tackled the loading of the paper), but a high-performance sailplane deserves it. The last two pictures show her with half her underpants on and with both side on, ready to present herself to the world.

The silver graphics Callie made for me duplicate exactly the original ones and really pop against the royal blue background. It is now all buttoned up and once I add my FAA registration number ready to maiden this week at Apache Pass. That was my target back in January when our event looked like a go and I made it with time to spare and no all-nighters either. Been a challenging assembly and I had to use much of my modeling experience over the years. Also, dug into my stock of hoarded materials many a time to overcome an engineering challenge. Here’s hoping the maiden goes well.

Sorry about the focus on the third pic. Now was the first time I looked at it off of my cell phone. Knew I should have used my camera...

[Mark9]

Well, my Ventus had her maiden this last Friday at the Apache Pass Aero Tow. It was very uneventful and she wanted to stay in the air. However, I wanted to just check her wings and get that first landing in to see how she handles coming in to land. All went well.

I put her up again late in the day, after my adrenaline levels tamed down, I believe a little before 5:30 PM. Found some light lift down low and turned on the thermal camber setting…WOW! She just grooved around in the thermal turn like on rails and began to climb out. Roll/bank reversals were smooth and very little energy was lost. Also, she would cover some ground quickly with an amazing apparent LD and I never used reflex.

Decided to come down since it was getting close to dinner time at the Ice House and brought her home. My landing was less than perfect. I got down to about 2’ and pulled in the air brakes. That was a mistake since that killed the lift being generated by the inboard flaps I have mixed in. She dropped the 2’ and bounced.

No damage was done though and my retractable gear did not collapse! So, my fix to the gear collapsing reported to me that I posted earlier in this thread was successful. No,redesign of the gear assembly is needed, only a little "adjustment" with the persuasion of a small hammer…YPIEE! All of my settings and mixing are very close and after a little tweaking this will be an awesome thermal machine. Thanks again to Alex and Soaring USA for hooking me up with this beautiful model. Wish now I had bought one earlier.

[Hoot]

Mark,
I met you at Apache Pass this past Friday. I was the guy from Houston asking all of the questions about towable sailplanes. I'm glad your first couple of flights went well for you !
Steve Gibson

[ARUP]

+1 Congratulations and what a very nice looking model and the sailplane looks great, too! lol