gosk8ing

Hey,

I have finally decided on my first scale glider; a CMPro Discus, which i got from Addies at a price of $195AUD, how could i say no!!!
I have seen some previous forums, and some people have strengthen the wing tube.

Should i strengthen my wing tube????

Also, I want to put in a main wheel and a tow hook for bungee launches.
Should i just put the main wheel in the same location as the full scale????
Where should i put the tow hook in reference of the fuse (remebering that i want to keep this a scale as possible)???

One last question...should i put my radio gear as fwd as possible (ive heard the glider ends up tail heavy??)????


Cheers

TFLG

There's a long thread over on RC groups on this plane. Yes you need to strengthen/replace the wing tubes, and the wing rod unless you are going to be very gentile with it. There is significant wing flex on these ships with the stock setup. I replaced the wing tubed and fuse tube with carbon fiber tubes and replaced the joiner with a steel one. Much better! With all scale planes you need to put the gear as far forward as possible and you will still need lead. I have 5 or 6 ounces in the front of mine. The fuse is also incredibly weak and adding some extra glass is not a bad idea. I did this but of course it cracked just behind where I added the glass.... It could be a very nice plane if they just bumped up the quality a bit but like you say, it's cheap!

TFLG

sigrun

Hi TLFG

Been following the CMPro Discus CS debacle thread to which you refer. Admire the changes you've made to yours which are certainly an improvement, but as you say, they can't address the primary issue which is it's simply not built to sufficient a standard of structural integrity for the task one might reasonably expect of it and as suggested by the manufacturer, let alone to last. Whilst it is comparitively cheap to purchase, it represents poor value unless the buyer's expectations are that circa 20 flights or approximately 1 months use before its demise is an acceptable service life to them? It's certainly not to me. Shame, as inarguably it is a magnificent looking bird temptingly price pitched at a point pretty much any RC peon can afford, and the forthcoming Ventus if its to be similar scale as the website suggests, should be similarly so.

Impulse buyer excitment inducing "Got to have one! Buy me now!" box art and undeniably beautiful finish out of the box are essentially worthless bling, unless you just want to admire it as a display model and derive a sense of good value from that, which as it stands is all it is essentially reduced to at present. A beautiful one, but still a hanger queen.

Admittedly, when flown by a majority of RC fliers, model versions will receive much more of a hammering without regard or observance of structually limiting speed envelope and 'g' considerations that a real Discus CS would. But I think we'd all agree that the model manufacturers should take that into consideration and compromise by building accordingly even if including a caveat with the product alerting buyers and fliers to some limiting considerations in operating a sailplane of that mass, span and structural integrity.

From what I've read so far, several undeniably experienced users, some of whom are flying it quite conservatively with intelligent regard to its potential issues, have experienced similar structural integrity compromised airframe speed induced ocilllations and twisting of the wing so the outer section is incidence unstable distorting to negative inducing consequent control problems, which height dependent may be recoverable provided the airframe remains intact during the prolonged recovery, or not.

I have been so tempted to buy one as I have plenty of time in real Discus CS' which are a superb standard class ship in terms of performance and handling friendliness. I suspect though, that RC fliers oftimes forget and some are simply unaware that even higher performance in class contemporary sailplanes such as the Discus CS are still lightly built relatively slow aircraft with a conservative Vne in comparison with even powered lighties, and when operating up around Vb, Va, Vno when such considerations are observed as they should be in typical good summer thermalling weather in this country, the speed and or manoeuvering envelope is fairly constricted with reference to speeds, loads and scale, reference, way below that at which we fly our models...even allowing for and appreciating the variance in mass. This btw, is not to suggest that in this case, the end users are responsible for their in flight failures. Observably from the incident reports, this particular (model) design clearly has a structural integrity problem.

Sincerely hope you have better luck with yours. A parting more general comment. Scale or sport like the Morton or Omei, beautifully finished and attractively priced they may be and weight it might keep down, but CMPro's fibreglass with the thickness and fragility of an eggshell really need to go. I wouldn't buy one ever for this reason. I've seen the falling to pieces and cracking fuselage results within so few flights. So call me odd or even Scrooge if you will, but I expect more even for that money.

Slope Flyer UK

I bought one of these here in the UK, but decided to sell..........as I just didn't think it was strong enough for the way I fly.

The wing joiner system was my biggest concern.