Skeeter Jr.

[bryancobb]

I would say any "zinc-rich" 2-part, epoxy primer would be the best.
I'd stay away from spray-can stuff, or any quick dry lacquer unless your goal is to prevent surface rust in the very short term.

PPG DP-75LF is the Cad-Dil-Lac product but it has a red oxide color.

 

[HobbyCAD]

Final assembly has now at last begun!!

I've been a busy bee these last couple of days, getting the basics together. The frame came back from media blasting, with a light coat of zinc phosphate primer on it. I opted to paint the fixed frame parts a machinery grey, with the moveable chrome moly parts painted aluminium, to match the nickel plated and anodised parts. I currently have an old transmission fitted, I will paint the one I'm rebuilding a spinnaker blue.

The foam tubing around the skid tubes are a temporary thing, to not scratch the skids while I'm building.

From here on, the next task is connecting up the throttle to the governor actuator and correlator. I'll then get the engine installed again, and couple up the drive system. After that, the target is to install the tailboom and TR transmission. Electrics and plumbing go in next. It's all coming together now.

More pictures to follow soon.

 

[HobbyCAD]

.. some more pictures.

 

[Blue Chips]

That sure look great Francois, glad to see it progressing.

I like the friction set up for Collective and Cyclic, is that using phenolic block?

I re-read and did not see what model engine you will be using?

Ken

 

[HobbyCAD]

Hi Ken,

Yes, my friction setup is made up of arms clamped between phenolic blocks. I have to give credit where credit is due, they are a copy of the Dennis Fetters's setup implemented in the Mini-500.

I'm using a Yamaha 130FI engine to power my helicopter, I've attached some pictures taken during the prototyping.

I've discovered an old scanned copy of the Pop Emigh booklet you asked about. I'll e-mail it to you now, let me know which pages are unreadable. I'll rescan those.

Cheers,

Francois

 

[Blue Chips]

That is fantastic on the Emigh booklet, thank you.


The Yamaha 130FI ought to make Skeeter jr a really fun flying and excitingly powerful little helicopter.

Curious, you do the welding on the tubing?
I guess if there is anything on this planet I am good at it is gas welding, literally have probably welded miles of it.
The welds look good!


Ken

 

[HobbyCAD]

Ken, the booklet and calculator sent to the e-mail you provided.

Yes, I did the TIG welding myself. Self-taught under supervision of our aircraft welder at work. It was a damn steep learning curve!! The little things such as not setting the down slope and post gas flow correctly came back to bite me. When pressurising the frame, I must have repaired 20 little pinhole craters where the welds stopped. It was there where I did not slope down the current, and did not flow the Argon until the weldpool solidified properly. So we learn.......

Cheers,

Francois

 

[Blue Chips]

Francois,
I know you tried before and It never arrived, I'll PM you now and include my isp email address.
The email address provided is good , not sure what goes wrong.

Thanks again.

Ken

 

[Blue Chips]

It came in finally Francois, hope you get this in time.

Ken

 

[Barney Bahle]

Lookin' good Francois. Your foam skid protectors reminded me of a set of skid-savers I read about on another forum. A guy took a piece of PVC the same length and inside diameter to match-up to his skids, split it in half, and secured it to the bottom of each skid, like a full length skid shoe. Wether it's a good idea or bad is up to you, just something to consider.

You'll have to excuse my ignorance on the next question. Why the interest in zinc rich primer on the chrome molly? This is something I need to know as I'll be painting my frame soon. Maybe you paint gurus will be willing to share some experience.

 

[HobbyCAD]

Hi Barney,

My foam protectors are a temporary thing while I drag it around the workshop. I don't want to wear the bottoms down on the cement floor, without even flying a bit! I am sorry I did not purchase thicker walled tubing for my skids.

The yellow and green zinc primers have been the aviation industry corrosion resistant self-etching primer standard for eons. They offer a maximum adhesion to bare metal. It's a sort of chemical bond to the bare base metal. Historically, zinc chromate was always used, but this has been replaced with a more eco friendlier zinc phosphate primer.

See the handy spray can aviation primer products from Tempo, P/N A-701 and A-702. http://www.aircraftspruce.com/pages/cs/primers/zinc.php

Cheers,

Francois

 

[Jincamty]

Hi Francois,

I am about to order some chromolly tube, and without going through all the math, can you tell me what wall thickness's you are using?
I didn't realize there are so many choices.

Your project is looking great! Can't wait to see more.
I will start a build thread once I get some parts made.

Cheers Cam.

 

[HobbyCAD]

Hi Cam,

Most of it is 0.035" wall. The 4 main vertical tubes are a bit beefier at 0.049" wall, the transmission mounting tubes are 0.058" wall thickness.

You can't go wrong to pressurize your frame in flight. That way, a frame tubing crack will immediately be detected.

Looking forward to your pictures, or seeing what you are building this time.

Cheers,

Francois

 

[Jincamty]

Thanks for that.

I have most of a CH-7 here with the pressurized frame. Great, simple idea!

Cheers Cam.

 

[HobbyCAD]

Hi Cam,

Are you keeping it with the fully enclosed bubble canopy? Look what this Chinese guy did to his.

Cheers,

Francois

 

[Jincamty]

No, the CH-7 isn't mine. It's being stored here for me to drool over.

Great machine to get ideas off.

I haven't seen that heli before. looks like he would be missing a fair it of forward/down view. Looks nice though.

Cheers cam.

 

[Jincamty]

Any updates Francois?

I hope you're not letting work get in the way of your projects

 

[HobbyCAD]

Hi Cam,

I have just last week started back up on my Skeeter Jr.

I remade the tailboom support collar, I was not happy with the previous design. It is in it's final stages of prepping, before painting it this weekend.

I this week made the horizontal and vertical stabilizer to tailboom attachment. I'm not attaching those to the tail transmission, as in the Mini-500. If you whack the standard Mini-500 tail into the ground, the attachment bolts strip out of the casing. There are no spare casings lying around any more.

I have also finally decided on my fuel tank configuration. It went from spun aluminum tanks, ala Bell-47 style, to 2 good quality plastic containers strapped to the side, ala the original CH-6. They are strapped onto 2 frames, left and right, right on the CG line. I have quick disconnect couplings on them, it will be easy to go and refill the tanks, or carry spares on the back of the ute.

I hope to finish painting my tailboom this weekend, and post pictures of my progress.

Cheers,

Francois

 

[HobbyCAD]

Not too much progress to report. I have started the sheetmetal work on the vertical and horizontal stabilisers.

Cheers,

Francois

 

[HobbyCAD]

Slowly getting there....