Schwing Corsa 2.75m (secondary market purchase)

[Konrad]

I know for a fact that Zhou did knowingly buy faux carbon.

Doc.

Yikes!!!

I don't "know" this as the only way I know to tell if the material is carbon fiber would be with a SEM (Scanning Electron Microscope). Being retired I don't have access to one. Doc as a materials scientist, do you have an assay to determine if the fibers are carbon verses has carbon? Particularly for those fibers held in a plastic matrix.

I wouldn't be at all surprised. China where the government holds control over the means of production and has an abdominal record with integrity. I'm thinking of the fatal baby formulas, deadly dog food and lead paint on baby toys. This is why it is so critical that the buyer (Apple, Boeing and Aeroic) have a robust QC program.

 

[Doc James Hammond]

Yikes!!!

I don't "know" this as the only way I know to tell if the material is carbon fiber would be with a SEM (Scanning Electron Microscope). Being retired I don't have access to one. Doc as a materials scientist, do you have an assay to determine if the fibers are carbon verses has carbon? Particularly for those fibers held in a plastic matrix.

I wouldn't be at all surprised. China where the government holds control over the means of production and has an abdominal record with integrity. I'm thinking of the fatal baby formulas, deadly dog food and lead paint on baby toys. This is why it is so critical that the buyer (Apple, Boeing and Aeroic) have a robust QC program.

Burning, Konrad.

Doc.

 

[Konrad]

Atomic (flame) absorption spectroscopy would only tell me if there is carbon present. It wouldn't tell me anything about structure. For all I'd know it would be just a lump of coal! Structure is key in the term carbon fiber.

 

[Doc James Hammond]

Atomic (flame) absorption spectroscopy would only tell me if there is carbon present. It wouldn't tell me anything about structure. For all I'd know it would be just a lump of coal! Structure is key in the term carbon fiber.

Carbon (fibre) burns readily - just like charcoal - especially if wicked by a nice epoxy flame agent.

I once landed my carbon model on a 24,000 Volt power line. Kaboom! The carbon exploded ito a really cool (not so cool at the time - but looking back) fireball.

Looking at the remains, there were the glass layers, a bit black and some a bit melted, but more or less intact. The carbon had virtually vaporised with almost no evidence to be found.

Doc.

 

[Konrad]

Carbon to carbon dioxide in milliseconds!

 

[Doc James Hammond]

Carbon to carbon dioxide in milliseconds!

Yep...Kaboom!

So all you have to do to check that you REALLY have a carbon model, is simply to connect it to any suitable high voltage outlet in your area. Car Jumper leads work well and anything over 12,000V will work fine.

Doc.

 

[Konrad]

Yikes!! Zhou can you say premature folding wing!!!

I don't think this wing can tollerate the FAI limit of 75g/dm^2!

The sine wave web flows off the spar caps! it also looks like the spar caps aren't well attached to the wing skins.

 

[Doc James Hammond]

To Quote Zhou when accosted for dangerous contruction including the actual failure of 3 models:

"You are only the designer! our workers (His mother, father and brother in law) don't want to do it your way!

I wonder how long it will be before the others now working with Zhou find this out?

Of course it all starts so well..."Yes, of course, no probem, trust me, I would never do that..." etc etc.

vindicta bonum vita iucundius ipsa

Doc.

 

[Konrad]

I'm still trying to figure out how this wing was destroyed on the lay up table.

Good practices question. Are the wings built with the bottom down and the top placed on top as the clamshell is closed prior to being oven cured*?

I would think that building the wing with the top down the builder could make sure that the spars and structures where fully bonded to the top skin. This way any bonding (life) issues with the assembly beads would be limited as the voids would be under tension for most of the life of the model. This would minimize the wing failing (top skin buckling). I say this as I spend a lot more time pulling positive G's than negative G's.

*Are these even oven cured?

 

[Konrad]

...

I wonder how long it will be before the others now working with Zhou find this out?

Of course it all starts so well..."Yes, of course, no probem, trust me, I would never do that..." etc etc.

vindicta bonum vita iucundius ipsa

Doc.

Is Zhou doing business under any other name other than RGMCN? Is he the OEM for other brands?

I'm a slow learner but like with RCRCM these Zhou builds are now on my DO NOT BUY LIST! This has nothing to do with any contract or business disputes. I'm taking this stand purely on the quality of the products, I as the end user have been forced to deal with. I have a dozen gliders from RCRCM and Zhou that really are unusable as purchased.

Now I have about 4 models by TJIRC that are in the same market segment as RGMCN and RCRCM. But unlike RGMCN and RCRCM, TJIRC Is continually trying to improve their quality and engineering of the products they manufacture. I see this with each production run!

Now If Aeroic working with Frank can get a handle on these manufacturing and quality issues we as modelers should have some slope gliders that are of real value.

 

[Doc James Hammond]

I'm still trying to figure out how this wing was destroyed on the lay up table.

Good practices question. Are the wings built with the bottom down and the top placed on top as the clamshell is closed prior to being oven cured*?

I would think that building the wing with the top down the builder could make sure that the spars and structures where fully bonded to the top skin. This way any bonding (life) issues with the assembly beads would be limited as the voids would be under tension for most of the life of the model. This would minimize the wing failing (top skin buckling). I say this as I spend a lot more time pulling positive G's than negative G's.

*Are these even oven cured?

Hi Konrad.

Normally the wings are built bottom up with the top skin bonded later. But it can be done either way.

The spars must be cut and faced (I do not face them - that is a Zhou invention) accutately to thickness so as to fit well between the top and bottom skin and make sure the bonding is good.

The models are "oven cured" which is actually better described as a "Hot room" but the temperature cannot be controlled other than "Hot". In the winter and summer the temperature varilation could be a lot. Same for the layup place - if its cold in winter which I can tell you it is in Wuhan - they heat the resin which is a diabolical practice

But its easy to tell a winter plane from a summer one. Just weigh them both. The viscosity of the resin is far higher and the pot life of heated resin is far shorter so the winter model will be significantly heaiver than the summer one.

Zhou's "Temperature controlled working environment" is actually a large commercial cooling fan for summer use only.

Cheers,

Doc

 

[Doc James Hammond]

Is Zhou doing business under any other name other than RGMCN? Is he the OEM for other brands?

Yes he is. I won't mention who they are but you'd probably recognize the names.

I'm a slow learner but like with RCRCM these Zhou builds are now on my DO NOT BUY LIST! This has nothing to do with any contract or business disputes. I'm taking this stand purely on the quality of the products, I as the end user have been forced to deal with. I have a dozen gliders from RCRCM and Zhou that really are unusable as purchased.

Your standards are high, Konrad. Most people don't get past the price stickers

Now I have about 4 models by TJIRC that are in the same market segment as RGMCN and RCRCM. But unlike RGMCN and RCRCM, TJIRC Is continually trying to improve their quality and engineering of the products they manufacture. I see this with each production run!

Yes I think Jerry has actually realized that a ittle care in the building takes no longer than a shoddy layup but results in a better models. If this doctrine can be instilled in his workers it will lead to increasing quality products.

Now If Aeroic working with Frank can get a handle on these manufacturing and quality issues we as modelers should have some slope gliders that are of real value.

Trust me - Frank is extremely well aware of what must be done and how to do it. He is now in the new factory along with an initial hire of 6 new people (all without bad habits) I am in daily contact.

Cheers,

Doc

 

[Konrad]

...

Your standards are high, Konrad. Most people don't get past the price stickers

Yes I think Jerry has actually realized that a little care in the building takes no longer than a shoddy layup but results in a better models. If this doctrine can be instilled in his workers it will lead to increasing quality products.

Trust me - Frank is extremely well aware of what must be done and how to do it. He is now in the new factory along with an initial hire of 6 new people (all without bad habits) I am in daily contact.

Cheers,

Doc

Really? I just want the work done correctly. It is a shame that is a high standard. I hope all my arrows and such can help educate the perspective customer as to what to look out for. This way the cream can rise to the top. Let the masses run to the bottom of the price quality matrix.

But I think I know what you are getting at. Yes, I'm an outlier on the Gaussian curve. Heck the wife often says I'm six standard deviations from the norm (way out there)!

Now I place little value on cosmetic concerns, I'm focused on fit and function. Fortunately or unfortunately I have the background to actually try to asses if things are done correctly or not. Form follows function!

With this wing I just poured 2cc of epoxy into that gap between the spar cap and the wing skin. I tipped the wing to allow the epoxy to flow towards the root, I don't know where it went. I still have a large gap.

I've seen some of Frank's work, other than being a bit on the heavy side it is well done. Better to be a bit heavy rather than what I see in this model. I hope the partnership between Frank and Aeroic results in high quality usable parts.

 

[Doc James Hammond]

"I hope the partnership between Frank and Aeroic results in high quality usable parts."

Well, probably time for an update here so I'll post this in the Aeroic section too:

Frank Chang - Eagle Soaring Devices, China.
Frank is a really good learner who only wants to make his models well. He knows that this is the (only) road to success - by being better than others. He knows his own skills and limitations and so is quite happy to take advice and is even happier when because of taking advice he sees his products improving. So far, although there have been (many) times I could have happily strangled him; with mutual patience and perseverance, this partnership is working out.
With the new factory that he moved into yesterday, Frank will soon be the biggest, and the best - at least in Asia.

Aeroic Taiwan.
To back this goood start in China up, I will start a new facility in Taiwan for production process R&D, new model development, and OEM/ODM projects. This will be a protype workshop and include a large and highly accurate CNC router. Mould cost in the model glider industry is an absolute killer so I will make all our male moulds as soon as the machine is situated. Right now its on order.

I have 6 completely new models already done in CAD, ranging from a 4m scale areobatics model, to a "teeny" 2.75M relacement for the Aresti 108.

Good things are happening!

Cheers,

Doc.

 

[Konrad]

Poured another 1.5cc to 2cc of epoxy down the wing to fill the void between the spar caps and wing skin. I now see a meniscus (surface) radius forming. I'm confident that the spar cap is bonded to the wing skin. (I don't think it will break up in the air) With the added 5cc of epoxy I'll have to laterally balance the model. This is always a good idea.

I have installed the HS08a servo trays. Changing from the CA'd servo trays to the epoxy'd in tray has removed a lot of top skin distortion. I'll have to keep an eye on this as the epoxy fully cures. Now it is time to see if Aloft's KST order has landed!

 

[Konrad]

All up weight is 2.25 Kg with 170 grams as balance weight @ 105mm CoG.

I removed approximately 140 grams of buck shot early on. I don’t know what the CoG was when I purchased the model.

I might make Sunset with this.

 

[Konrad]

Doc. Your 105mm must be different than my 105mm! I set the CoG at 104mm I then added 30 grams of loose weight. Well, the test flight was INTERESTING! I was on the edge of divergent flight in pitch. As the air speed built up the plane would tuck. This means that pitch was all but impossible to control going in and out of the turns (up & down wind).

With the aft CoG the elevator was way too sensitive. As a result I stalled a lot. The good news was that the air would reattach easily. I did get a wing to drop a lot. As I was looking into the sun I'm not to sure how the stall developed. So I don't know if it was just because one wing was heavier. Or if there is an aerodynamic reason for the wing to drop. I think it is a mass issue (heavy wing) as the snap flaps with programed washout flew fine.

With the pitch issues I had a difficult time keeping the nose down to penetrate without a dive. This proved to be a problem while trying to land. I found that in crow things seemed to settle down a bit in pitch. But I really didn't need the drag from crow. After the fifth attempt at landing I just went for it. As a result I wound up in the rear rotor. The Schwing Corsa made a nose first tumbling landing into the back of the hill.

I'm happy to report the tightened joiner pass through, add epoxy to fill the voids, the added cording to support the servo tray and added cotton flocks ( filler) to support the ballast tube all paid off. There was no damage to the Schwing Corsa 108.

As a side note this Schwing Corsa 108 is now at the same weight as my light glass lay up Redshift (green).

 

[Konrad]

As is normal for me I let a contest flying event interfere with my build and test flight schedule! I was up until late Friday night trying to get all the servo installed and working. I was able to get the RX and Tx to talk to each other. Then I realized I didn't have any servo covers that would allow for the Servorahmen arms to extend above the wing skin. These Servorahmen servo arms are rather wide. This means that the classic jelly bean servo covers wouldn't work. With the use of the classic surface control horn one needs to use an inordinately long servo arm. So I laid up a crude set of covers and went to bed.

Woke up a 5:00am (as a retired guy this is unnatural !) I popped the cover off the glass sheet and threw them into my bag. I loaded the car and drove to Sunset Beach. I was hoping that the wind would be low in the late morning which would allow me time to finish my set up of the Schwing Corsa 108. With the Mike Shellim's Templet I was using I knew the programing would be straight forward. The only question would be had I set up the servos to allow the control I wanted. In the end I had, other than the rudder. I'll need to rework the rudder push rod. But to my thinking this moderate rudder movement would be more than adequate for a maiden flight.

While waiting for the lift I took the time to fit the flap servo covers. I let the time for the drive down cure the epoxy. While fitting the covers I recalled a trick I learned form @Motowncali on the use of tape to aid in the transfer of features. This worked great and only left the corner radius to the classic trial and error fitting process. I was pleasantly surprised to see that Mo had made it down the Sunset. We swapped horror stories of trying to set up models from Zhou.

 

[Doc James Hammond]

As in normal for me I let a flying event interfere with my build and test flight schedule! I was up until late Friday night trying to get all the servo installed and working. I was able to get the RX and Tx to talk to each other. Then I realized I didn't have any servo covers that would allow for the Servorahmen arms to extend above the wing skin. These Servorahmen servo arms are rather wide. This means that the classic jelly bean servo covers wouldn't work. With the use of the classic surface control horn one needs to use an inordinately long servo arm. So I laid up a crude set of overs and went to bed.

Woke up a 5:00am (as a retired guy this is unnatural !) I popped the cover off the glass sheet and threw them into my bag. I loaded the car and drove to Sunset Beach. I was hoping that the wind would be low in the late morning which would allow me time to finish my set up of the Schwing Corsa 108. With the Mike Shellim's Templet I was using I knew the programing would be straight forward. The only question would be had I set up the servos to allow the control I wanted. In the end I had, other than the rudder. I'll need to rework the rudder push rod. But to my thinking this moderate rudder movement would be more than adequate for a maiden flight.

While waiting for the lift I took the time to fit the flap servo covers. I let the time for the drive down cure the epoxy. While fitting the covers I recalled a trick I learned form @Motowncali on the use of tape to aid in the transfer of features. This worked great and only left he corner radius to the classic trial and error fitting process. I was pleasantly surprised to see that Mo had made it down the Sunset. We swapped horror stories of trying to set up models from Zhou.

View attachment 11020
View attachment 11021

The new servo hatch/cover for the fuse on the latest version is for a double install Konrad - again this came from Mo.

Doc.

 

[Konrad]

I like the Mo mount in my Gremlin. I assume the "new" one is much the same as the Gremlin Mo mount. My concern here was that the flat plate servo cover was fighting with the start of the bottom radius.

Now I need to say I'm a bit concerned with weight as I'm already at the same mass as the glass Redshift lay up. I was going to go with an HS08a at 11 grams but backed away to use a 9 gram X080 plus. I'd have to graph/map out their moment arms, the lower mass of 2 X08, one signal wire and the loss of the long rudder push rod verses an X08 and a 215 and rudder push rod . Sounds like a good problem for a CAD program.