Soaring USA gift certificate (Strega purchase?)

[Konrad]

Lets see what am I trying to show here, that I'm a fan of FrSky?

No, I want to show how the first stage of primer should look. First I need say that all sanding needs to be done with some kind of backing, preferably a hard backing. This helps greatly from undercutting the surface.

On this repair I used a sanding block to shape and feather in the repair patches. At an optical level this shows up as a faceted surface. You can plainly see this with the nose part of the repair in the longitudinal nature of the primer marks.
You can also see the edges of the bandages in the primer aft of the wing fairing. This indicates that most of the fibers weren't under cut when feather edging.

The main purpose of primer is to fill the scratches from shaping the repaired area and to fill any low spots. It is not to add weight as is so often the case. Here I used a stiff foam rubber pad and 280 grit sandpaper. I will add a second layer of primer and sand until I hit parent material with 280 grit. I will then switch to 320 grit until I get a surface suitable for the finish coat. For light color 320 grit is adequate, for darker colors I often move to 400 grit.

Note the only time one might sand without any backing is in tight areas, such as filets. But it is best to make some shaped sanding blocks for these areas. Also sanding to clean out low spots in preparation of adding filler.

Avoid sanding with ones fingers or hand as the sandpaper backing. You are likely to destroy the surface as you will be imparting the shape of your fingers and hand into the surface. This just looks gross!

I know, I know I should stop trying to make a silk purse out of a sow's ear. (RCRCM products aren't worth the effort)! Again I'm using this crap as practice. I haven't done any refinishing work in 40 years. Wow, have the materials changed!

When it comes to sanding products I really like the performance of 3M products, than hasn't changed.

All the best,
Konrad

 

[Konrad]

That's not a bug, it's a feature! The first time I heard a Microsoft rep. say that I laughed so hard I almost peed myself.

What we have here are those horse hairs in the fiberglass. I can see where they are nice to tell when you have undercut the glass.

Well, I'm really pissed at constantly having the LE open up on my Yellow and black Strega. I've noticed this happening just while trying to stabilized the model right before launch. If you touch the wing to keep it level the leading edge will pop. To stop this I've filled the LE wing root with expandable foam (this is a desperate and dangerious move). I then sanded the LE to remove the glass skin near the LE part line. I removed the old glass to make room for the new glass skins I will add that wrap around the LE to give me some fiber support across the part line. I under cut the glass so as to not change the airfoil shape with the added layers of glass.

Now I found the horse hair was a nice indicator for when I had removed the fiberglass.

All the best
Konrad

 

[Konrad]

It's always a good morning to wake up to cured epoxy!

Here I'm showing that I have placed 3 layers of 0.75 oz glass cloth across the LE part line. This was done in an attempt to get some fibers to add strength to keep the top and bottom skins attached to each other. This and the added expandable foam should add "some" durability to the wing to withstand normal handling.

This part line failure seems to be a weak point in the design of molded wings. With this being known the bonding of the two skins needs to be done with a great deal of care and with adhesives of the highest quality and performance.

At the point of manufacturing mixing cabosil into the laminating epoxy to make a LE bead to be used as an adhesive is not adequate! I know that Fokker Aircraft used a lot of very strong adhesives in their aluminum bonding of aircraft structures. This stuff was fantastic, but needed to be stored in a -20 freezer and still has a short self life.

So there are adhesives available to address the limitation of the molded wing. It is just that it needs to be used. They may not be the most convenient to use and a bit expensive (short shelf life). But they are needed to get a strong wing.

All the best,
Konrad

 

[Wayne]

Correct me if I am wrong, but the only time you have those horse hairs in fiberglass is as a marker that the fiberglass is not designed for structural loads, but intended for PCB manufacturing. AKA cheap junk.

 

[Doc J]

Correct me if I am wrong, but the only time you have those horse hairs in fiberglass is as a marker that the fiberglass is not designed for structural loads, but intended for PCB manufacturing. AKA cheap junk.

You are not wrong Wayne. Not only that its really CHEAP PCB glass.

Doc.

 

[Konrad]

NO, Tell me it isn't so, that RCRCM is cheap junk!

 

[Wayne]

Sorry, didn't know how to break the news to you.

 

[Konrad]

LOL,
Break, is the key word here!

 

[Doc J]

I wouldn't mind, but if they hadn't changed the design, then made such a crappy job of producing it - it would have been quite a nice model in its day.

It did do a 30 sec time in 2008...

Doc.

 

[Konrad]

I'm surprised at just how different the Yellow and Black Strega flies verse the White and Red Strega. Both are glass ships but the White and Red actually flies well. The Yellow and Black one flies OK but seems to Flex more making it hard to put her where I want her.

 

[Doc J]

I'm surprised at just how different the Yellow and Black Strega flies verse the White and Red Strega. Both are glass ships but the White and Red actually flies well. The Yellow and Black one flies OK but seems to Flex more making it hard to put here where I want her.

Sounds like a bad case of PCB glassitis to me Konrad...

Doc.

 

[Konrad]

Maybe, but I'm thinking it might be epoxy. The yellow and black one showed a lot more distortion as a result of shrinkage. Hinge line TE skin pulled up as a spoiler. The glass weave and support structure show in the surface. These are both 8 to 9 years old. I wonder if RCRCM put these into post cure ovens to heat threat the epoxy. There is so much about materials and process that I don't think RCRCM understood.

Also RCRCM uses balsa wood as the skin core. This natural material makes it almost impossible to have a stable base to place the lay ups upon.

BTW; I like the structural foam skins. Both for its consistency and the way it performs to impacts. Balsa tends to "Shatter" along the grain running away from the impact zone . Foam tends to crumple leaving the damage confined.

 

[Doc J]

Maybe, but I'm thinking it might be epoxy. The yellow and black one showed a lot more distortion as a result of shrinkage. Hinge line TE skin pulled up as a spoiler. The glass weave and support structure show in the surface. These are both 8 to 9 years old. I wonder if RCRCM put these into post cure ovens to heat threat the epoxy. There is so much about materials and process that I don't think RCRCM understood.

Also RCRCM uses balsa wood as the skin core. This natural material makes it almost impossible to have a stable base to place the lay ups upon.

BTW; I like the structural foam skins. Both for its consistency and the way it performs to impacts. Balsa tends to "Shatter" along the grain running away from the impact zone . Foam tends to crumple leaving the damage confined.

Aha - memories coming back...you could be right.

The RCRCM Method:

In the winter it can be deadly cold in Jinan - in fact well down into the sub-zero range. As there is no temperature control whatsoever in the factory, to make the models, the workers heat the epoxy in order to render it runny enough to wet the fibres. The heating was done by immersing the mixed (or not) epoxy batch in a pot of simmering hot water. As you can imagine, in minus temperatures it does not stay runny very long. The result is that winter produces badly bonded, and usually heavy models with the epoxy cure questionable at best.

To add to the lack of control, the "Oven" (cure or post cure) is a small room heated by metal buckets of red hot, smoking artificial charcoal. Its actually really dangerous as the charcoal consumes all the oxygen in the space very quickly, and spending more than a few seconds in the room - filled as it is with sulphur fumes - can quickly (and has) result in loss of consciousness.

In the summer the Jinan temperature can be, and often is over 100 degrees F, so the workers have learned to make smaller batches of epoxy and in fact they normally designate a younger or newly joined member as the "Mixer" This "Epoxy monkey" Constantly mixes epoxy in small batches of about 30 grammes which are used to make whatever is on the table.

In order to try to prevent this "quality gambling" according to the seasons with my models, I insisted that when Zhou moved from the original animal pen building that he started in, he install a temperature control to heat in the winter, and cool in the summer - which he swore to me he had done.
It later turned out that his "temperature control" was a small electric fan.
I also found out that he was also heating the resin in winter, though he used a more sophisticated system - the resin and hardener were kept in two non-adjustable temperature crock pots at about 80 degrees. (Which is way too hot)

This may seem hard to believe, but I assure you that its true.

Doc.

 

[Konrad]

YIKES!!!

 

[Wayne]

But that was such a wonderful looking animal pin.... to be murdered in!

I recall once you sent me a photo of a new plane and I said something like can't they take the planes somewhere prettier for the pictures and your answer was they did. Sort of looked like a dark alley way behind a rendering plant.

 

[Doc J]

But that was such a wonderful looking animal pin.... to be murdered in!

I recall once you sent me a photo of a new plane and I said something like can't they take the planes somewhere prettier for the pictures and your answer was they did. Sort of looked like a dark alley way behind a rendering plant.

You are right Wayne...it was pretty horrendous.

Even the RCRCM place was better. I never saw Zhou's second factory - I think I am glad about that.

Doc.

 

[Konrad]

Well, it finally looks like the Stregas’ are coming into their own. Flew both yesterday in an F3F race and both came home without needing any rework or redesign.

I choose to fly the Yellow and Black Strega as I had just repaired the broken tail boom (again). Also the Red and White Strega was starting to show instability in the flap hinge line. With the Yellow and Black Strega I had reinforced the flap hinge with 3M 5200 compound. With the hinge as found with these RCRCM products, I’m learning that it is best to add the reinforcement prior to loosing the surface (hinge failure).

I was a bit surprised to find that the Yellow and Black Strega had become a bit tail heavy with all the boom repairs. towards the end of the race I added 14 grams of nose weight and saw improved flight handling. I’d have thought that the repair of the leading edges with the expandable foam and glass would have balanced out the tail boom repair.

It's been brought to my attention than some folks think I’m overly critical of RCRCM. While I am under no delusions that products manufactured by RCRCM were meant to be anywhere near the quality we see from Eastern Europe. I would expect the the manufacture of the molded plane meet a minimum safety level and product expectation. I’d like to learn what is your take on my finding with RCRCM’s products.

To recap, Both Stregas’ suffered a gross safety issues in that the 3 out of 4 V-tail control horns weren’t bonded to the control surface. That one that was bonded only showed bonding on one surface of the control horn. As manufactured there were no torque arms in the design of the control horns.

Both fuselages showed willful disregard for structural support in that there were gaps in the carbon reinforcement at the point of maximum stress behind the wing fairing. Also both fuselages have little or no fiber across the fuselage part line along the tail boom. (front of the fuse did have glass fibers across the part line).

The Epoxy used has a high shrinkage rate as sub structure under the skin can be seen. Not only seen but felt. This disruption in the wing skin surface defeats any benefit of the molded slope soarer. The wings might as well have been made with open bay balsa ribs and covered in iron on film! The Yellow and Black Strega showed these issue to a far greater extent. The wing side of the hinge line had pulled up into an effective spoiler!

The Yellow and Black Strega had the carbon reinforcement patches for servo support misplace, that it only supported half the servo mounting area.

Now under “you get what you pay for” the fiberglass used to skin the wings and V-tail are of the lowest possible quality as indicated with that "horse hair” running through out.
Staying with budget issues Strega did have what one would expect from the bottom end of the price point. The masking for the paint is poor, the part lines are rough, canopy fit is poor, and the airframe flexes too much (see epoxy and glass issues). The Flex and to some extent durability are why I was warned, that if buying an RCRCM product only look at those advertised as carbon lay ups.

In my opinion for $700 the glass Strega is a very poor value. It might be attractive to the beginner looking for his first 3m class glider. Unfortunately these would drive any perspective F3F or slope flier away with the poor durability as a result of poor quality. Regardless of the price nobody should have to suffer products that are manufactured to fail!

I got my Stregas’ for 40% off and an additional $100 off using the Soaring USA gift certificates donated to the 2018 ISR (Big thanks to Soaring USA for this donation to the ISR) for a total of $535 each with tax and shipping. Even at that price I would have been better off throwing these in the crusher, rather than spend the time trying to fix the manufacturing issues. Now as this is a hobby I actually enjoyed trying to make silk purses out of these sow’s ears. I had fun with these carcass but I don’t think the general public would have. These RCRCM ships are probably one of the main reason so many folk leave slope soaring in utter frustration.

All the best,
Konrad

P.S.
If looking for an entry level 2.7 to 3m ship give the carbon Alpha 2.8 a good long look. At $850 it is a far better value than anything available from RCRCM!

Alpha 2.8m

Advanced glider builders and pilots will love this one. The Alpha 2.8m looks sharp with its black, red and white color scheme, clean lines and slippery, sleek profile. Available in either pure glider for the slopes or electric if slope soaring isn't your thing. A bare airframe allows you to put...

alofthobbies.com

 

[Konrad]

RCRCM the gift that keeps on giving, me the s**ts!

Under the heading trying to make a silk purse out of a sow's ear. Here I trying to make a spot repair paint job. I'm using PPG Delfleet Essential catalyzed paint. Everything was going great until I tried to fade out the over spray with reducer. This is when I learned that RCRCM is not using catalyzed paints in their painting in the molds You can see the results in the photo. I've not had this problem with the airframes from Sanda and Aeroic.

Yes I was trying to remove the branding as nobody rides for free! Ok, I liked the RC graphic and was trying to save that.

 

[Doc James Hammond]

Well, it finally looks like the Stregas’ are coming into their own. Flew both yesterday in an F3F race and both came home without needing any rework or redesign.

I choose to fly the Yellow and Black Strega as I had just repaired the broken tail boom (again). Also the Red and White Strega was starting to show instability in the flap hinge line. With the Yellow and Black Strega I had reinforced the flap hinge with 3M 5200 compound. With the hinge as found with these RCRCM products, I’m learning that it is best to add the reinforcement prior to loosing the surface (hinge failure).

I was a bit surprised to find that the Yellow and Black Strega had become a bit tail heavy with all the boom repairs. towards the end of the race I added 14 grams of nose weight and saw improved flight handling. I’d have thought that the repair of the leading edges with the expandable foam and glass would have balanced out the tail boom repair.

It's been brought to my attention than some folks think I’m overly critical of RCRCM. While I am under no delusions that products manufactured by RCRCM were meant to be anywhere near the quality we see from Eastern Europe. I would expect the the manufacture of the molded plane meet a minimum safety level and product expectation. I’d like to learn what is your take on my finding with RCRCM’s products.

To recap, Both Stregas’ suffered a gross safety issues in that the 3 out of 4 V-tail control horns weren’t bonded to the control surface. That one that was bonded only showed bonding on one surface of the control horn. As manufactured there were no torque arms in the design of the control horns.

Both fuselages showed willful disregard for structural support in that there were gaps in the carbon reinforcement at the point of maximum stress behind the wing fairing. Also both fuselages have little or no fiber across the fuselage part line along the tail boom. (front of the fuse did have glass fibers across the part line).

The Epoxy used has a high shrinkage rate as sub structure under the skin can be seen. Not only seen but felt. This disruption in the wing skin surface defeats any benefit of the molded slope soarer. The wings might as well have been made with open bay balsa ribs and covered in iron on film! The Yellow and Black Strega showed these issue to a far greater extent. The wing side of the hinge line had pulled up into an effective spoiler!

The Yellow and Black Strega had the carbon reinforcement patches for servo support misplace, that it only supported half the servo mounting area.

Now under “you get what you pay for” the fiberglass used to skin the wings and V-tail are of the lowest possible quality as indicated with that "horse hair” running through out.
Staying with budget issues Strega did have what one would expect from the bottom end of the price point. The masking for the paint is poor, the part lines are rough, canopy fit is poor, and the airframe flexes too much (see epoxy and glass issues). The Flex and to some extent durability are why I was warned, that if buying an RCRCM product only look at those advertised as carbon lay ups.

In my opinion for $700 the glass Strega is a very poor value. It might be attractive to the beginner looking for his first 3m class glider. Unfortunately these would drive any perspective F3F or slope flier away with the poor durability as a result of poor quality. Regardless of the price nobody should have to suffer products that are manufactured to fail!

I got my Stregas’ for 40% off and an additional $100 off using the Soaring USA gift certificates donated to the 2018 ISR (Big thanks to Soaring USA for this donation to the ISR) for a total of $535 each with tax and shipping. Even at that price I would have been better off throwing these in the crusher, rather than spend the time trying to fix the manufacturing issues. Now as this is a hobby I actually enjoyed trying to make silk purses out of these sow’s ears. I had fun with these carcass but I don’t think the general public would have. These RCRCM ships are probably one of the main reason so many folk leave slope soaring in utter frustration.

All the best,
Konrad

P.S.
If looking for an entry level 2.7 to 3m ship give the carbon Alpha 2.8 a good long look. At $850 it is a far better value than anything available from RCRCM!

Alpha 2.8m

Advanced glider builders and pilots will love this one. The Alpha 2.8m looks sharp with its black, red and white color scheme, clean lines and slippery, sleek profile. Available in either pure glider for the slopes or electric if slope soaring isn't your thing. A bare airframe allows you to put...

alofthobbies.com

The thing here thats REALLY hard to get your head around is that when making moulded models, its JUST AS EASY and TAKES EXACTLY THE SAME AMOUNT OF TIME AND MONEY to do it RIGHT as it does to do it WRONG.

Why then, do we see all these construction problems, if it's not time and it aint money?

The only answer is MANAGEMENT problems - and other than that I have absolutely no firetruckin' idea.

Really, absolutely, completely, utterly, none

Doc.

 

[Konrad]

Not true! It cost one, one's reputation!!! Also a higher grade of glass would cost a few pennies more. So would a higher grade of epoxy. True, the labor which is the largest cost is the same.

And you know it, THE ROOT OF ALL EVIL, IS ALMOST ALWAYS MANAGEMENT, be it government or corporate!