RE: Sig Wonder build thread

[66 Malibu]

The Sig Wonder has always been my top favorite airframe followed very closely by the Lanier Shrike 10.
About 10 years ago, when I started to gain interest again about model planes/engines, I saw a fellow at the local RC club do an incredibly fast high speed pass with a Wonder and it literally disintegrated in mid-air in front of all !!!
Thankfully the engine had a nylon zip tie tethering it to the airframe or the engine would have been in the next county..
Later someone told me that the Wonder had an OS32SX on it !!!!
Steve.....

[balogh]

[quote="Surfer_kris"]

Speaking of engines .... I like the Cox .09, but if you did not use that engine, there in Europe it is very possible to easily get this engine: MVVS .12 with pipe ... must be a very powerful engine, I suppose...

Yes, these engines are very nice. True ABC and twin ballbearings etc. The later version also had blue anodising on the head and prop driver. There where also several muffler options, one regular muffler, one quiet muffler and the "tuned" muffler (not a tuned pipe) that you show in the picture.

Sadly these engines are no longer made and are not easily obtained here either. Here are a few pictures:
.....quote]

They are still on fleabay, a bunch of them here:

https://www.ebay.com/sch/i.html?_from=R40&_trksid=p2050601.m570.l1313.TR0.TRC0.H0.XMVVS+model+engine.TRS0&_nkw=MVVS+model+engine&_sacat=220

[Surfer_kris]

I don't see any .12 engines there?
Are you referring to the Modela Junior diesel engine?

[balogh]

You are right Kris these 2,5ccm engines are 0.15 and not 0.12...class

[roddie]

Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..



I actually like this variant.. named "Das Wunder"

https://outerzone.co.uk/plan_details.asp?ID=9112

[1/2A Nut]

Per your question I can not answer based on field tests as a 7x4 is not the type of prop my projects
would be suited for, but can based on experience with the engine's power observations.

I have had numerous projects over my life time with them. What a 7x4 will do for a TD .09 is put out
good thrust but speeds won't be too peppy. In lieu of the plane being a Sig Wonder expect 21k unloaded
at best down wind passes with a black Cox prop 25% nitro, could see 85 mph ish. Less if with the grey prop.
If you must go with a 7x4 use a Master Airscrew brand it will make more rpm then your Graupner grey prop.


The Sig Wonder can go 100 + with the .09 will need to thin out the airfoil first among
a few other tricks such as speedy vertical stabs along with wing tip treatment.  
What is the wing span and Sq. In. of wing area??




AmpAbuser
Published on Jul 2, 2016

DART -TD .09
Best level pass 143mph / per prop calc / 5.25x6.25E
Wavescope: 232.07 kmh / 144.2mph /down wind  / 21,960rpm
The reading was taken at 1.52mins into the vid.
Temp 96F (16.9k to 17.1k rpm at launch) 30% nitro / 20% castor
 31.5 inches 106 Sq. In. wing / 11.7 oz RTF

 

[Surfer_kris]

You are right Kris these 2,5ccm engines are 0.15 and not 0.12...class

It was very different ten years ago, one could just order them straight from their website.
It is sad to see all the engine manufacturers disappear one after the other.

[balogh]

[quote="roddie"]Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..  

quote]

Roddie you are absolutely right, I have never thought of putting anything else into the nose of the Wonder than my COX TeeDee09...because of my love for COX engines...and second, because the next bigger engine I have is an OS Max FS56 alpha 4-stroke that equates in power a 0.28 2-stroke. The OS max would probably make it way too nose-heavy, and- unless totally throttled to idle - brutally and suicidally overpower the bird..

So I stick to the TeeDee09, the one with the home-made boosters in the bypass ports in order to partly compensate the use of amuffler and the R/C carb that both rob a bit of a power from an SPI engine.

[MauricioB]

Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..  

quote]

Roddie you are absolutely right, I have never thought of putting anything else into the nose of the Wonder than my COX TeeDee09...because of my love for COX engines...and second, because the next bigger engine I have is an OS Max FS56 alpha 4-stroke that equates in power a 0.28 2-stroke. The OS max would probably make it way too nose-heavy, and- unless totally throttled to idle - brutally and suicidally overpower the bird..

So I stick to the TeeDee09, the one with the home-made boosters in the bypass ports in order to partly compensate the use of amuffler and the R/C carb that both rob a bit of a power from an SPI engine.

András, I'm glad you have the engine set ... so it will be the Cox .09 Tee Dee ... is going to take your hair model you are going to see !!!
We recently exchanged queries on the RPM of my Tee Dee .09 with a 7 x 3 1/2 propeller, have you done any testing of your engine ??, what data did you throw?

[MauricioB]

Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..  



]

Roddie, that model, with that decoration and the brooch of the Cox there, can not be more American ... looks great!

[balogh]

Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..  

quote]



András, I'm glad you have the engine set ... so it will be the Cox .09 Tee Dee  ... is going to take your hair model you are going to see !!!  
We recently exchanged queries on the RPM of my Tee Dee .09 with a 7 x 3 1/2 propeller, have you done any testing of your engine ??, what data did you throw?

Mauricio,

Other than my used TD09 that pulls my Cosmic Wind, I have not yet tested the new TD09 with the booster ports in the cylinder...but I cannot delay it anymore, as I definitely want this powerplant to be in the nose of the Wonder.

I am particularly interested in whether the booster ports - that are missing from the stock TD09 cylinder, and were added to mine by a previous owner - will have the same performance enhancement effect we know from the cylinders of the 049 and 051 TeeDee-s....I expect a few 100's of additional rpm-s...

More to come soon...

[MauricioB]

Thanks for the link Marleysky.

I still have not tested one of my new TD09-s that came pre-owned but unused with the strange, probably home-made double booster ports in its cylinder, and I figure the boosters should add a few 100's of rpm-s...so I may be well off with this 09 on the SIG Wonder even if muffled and running on the R/C carb that both are expected  take some rpm away from this SPI engine..



BTW I will also try to oil-seal the R/C muffler with an O-ring pulled on the TD09 cylinder...COX mufflers are not quite effective in keeping the castor away from the engine cowl because the spent oil in the exhaust gases just flows down the cylinder in the gap between the muffler  neck and cylinder wall..I hope to keep the cowl at least a bit cleaner than when the engine is  un-muffled.

for what you say, it seems that this is handmade? ... that is, Cox never realized it?
It will be interesting to see the result! ... if that was done in a homemade way, it requires a lot of pressure not to ruin the cylinder ...

[balogh]

Yes, Mauricio,

because of the irregular shape of one of the booster flutes, and because they are not blackened like the boosters in 049 and 051 cylinders were blackened in the COX factory, I assume these were added by the previous owner.

I have thoroughly cleaned the whole engine to remove all possible burrs, and checked if the boosters are not too long to compromise the timing of exhasut and scanvanging, and visibly found them OK. The cylinder/piston fit is tight and fresh-from-factory (the grinding/honing marks are still visible like in any new COX engine), providing superb compression, with a notable pinch at the top-dead center - an indication of the COX Tapered cylinder design.

Now comes the real test on the bench after some careful running in...that we know COX engines typically do not need, but I want to run it through the recommended initial heat cycles of 3 minutes "4stroke" run-then cool-then 3 minutes "4stroke" run and on and on. Just to give the beasty the courting what she deserves before I take her to my - engine -bed..

[MauricioB]

Yes, Mauricio,

because of the irregular shape of one of the booster flutes, and because they are not blackened like the boosters in 049 and 051 cylinders are blackened in the factory, I assume these were added by the previous owner.

I have thoroughly cleaned the whole engine to remove all possible burrs, and checked if the boosters are not too long to compromise the timing of exhasut and scanvanging, and visibly found them OK. The cylinder/piston fit is tight and fresh-from-factory (the grinding/honing marks are still visible like in any new COX engine), providing superb compression, with a notable pinch at the top-dead center - an indication of the COX Tapered cylinder design.

Now comes the real test on the bench after some careful running in...that we know COX engines typically do not need, but I want to run it through the recommended initial heat cycles of 3 minutes "4stroke" run-then cool-then 3 minutes "4stroke" run and on and on. Just to give the beasty the courting what she deserves before I take her to my - engine -bed..

Well, .... regarding the bench test, it's something I enjoy and a lot. We talked in the club with my friends from a different stage for me, where this to start a motor, has become very pleasant, as much as flying a model.
During the march, I can drink beer and listen to the engine, watching as it gets soaked (it gets wet) from the post combustion oil .... ahhh can also be accompanied by mate, instead of beer ... it's a customs by these sides, take mate ....

[balogh]

Your love for the Cox engine should make the Tee Dee .09 the obvious choice Andras.. just my humble opinion..  



]

Roddie, that model, with that decoration and the brooch of the Cox there, can not be more American ... looks great!

I also like the aesthetics of the Star Spangled Banner design of the Patriot, shown here with a TD09 in the nose,, but will probably opt for the equally appealing Angel which builds with fewer colors...http://www.towerhobbies.com/products/sig/siga0065.html

My planes typically look great as uncovered skeletons, problems of appearance start to proliferate once I apply the Oracover

[balogh]

[quote="1/2A Nut"]Per your question I can not answer based on field tests as a 7x4 is not the type of prop my projects
would be suited for, but can based on experience with the engine's power observations.

I have had numerous projects over my life time with them. What a 7x4 will do for a TD .09 is put out
good thrust but speeds won't be too peppy. In lieu of the plane being a Sig Wonder expect 21k unloaded
at best down wind passes with a black Cox prop 25% nitro, could see 85 mph ish. Less if with the grey prop.
If you must go with a 7x4 use a Master Airscrew brand it will make more rpm then your Graupner grey prop.


The Sig Wonder can go 100 + with the .09 will need to thin out the airfoil first among
a few other tricks such as speedy vertical stabs along with wing tip treatment.  
[color=#ff00cc]What is the wing span and Sq. In. of wing area??...[quote]

This is what I have on the dimensions:

Wingspan: 37.5 in (953mm) Wing Area: 338 sq in 21.8 dm² Flying weight: 26-38 oz (737-1075 g); I would like to keep the AOW down and this will be easy with the TD that weighs at least 2 onces less than the ASP0.12

[Surfer_kris]

With a modern radio equipment you should be able to get down to around 20oz, or better. Especially as there is no landing gear or anything else that is heavy.

Would/will be interesting to see the rpms for the two different liners.

[1/2A Nut]

Those are called boost flutes, Krin Kraft would mod engines that way.
But the flute ends higher up than what they would do just a hair into the lower
lip of the exhaust port as I recall. In theory should produce more fuel air mix into
the combustion chamber. The flute stops in time just under the top lip of the exhaust
port as you have shown so should work for more power!

At 338 Sq. In. with the weight of a TD .09 / modern gear it will be a floater on
landings. Will be a plane that should last a long time however wind will toss it
about a hair bit with the low wing loading. The thick airfoil will have it like a fun fly
on a .09 great for tricks 4ch / active rudders for flat spins and acro.

[balogh]

Thanks Brad,

I am getting more and more excited to build this kit and break in the COX TD09 stallion (or mare ?) the soonest ...based on my prior experience, I am not particularly concerned with flying it in wind.... in the past - when we were more than just myself in the flying field, - all pilots started to land and disassemble their birds and gear when heavier gusts came, with only myself left flying my 1/2 size and even smaller - but always COX-powered - R/C planes. Once I find the direction of the wind, I will take-off and land safely...though I admit I broke a couple birds in sudden side-winds on take-off, too.

Looking forward to completing and trying this one the soonest!!!

[balogh]

I started the build this weekend and completed the wing and the the firewall with the engine mount.
Like often I replaced the stock balsa leading edge with a hollow carbon 6mm*6mm square rod to better resist the hard terrain landings. The carbon rod adds 24 grams extra to the weight but I will save this by e.g. using a balloon tank instead of the clunked Sullivan tank SIG recommened, and other measures.




The ailerons are yet to be added, now I continue with the build of the fuselage.



The Tee Dee 09 sits far ahead in the nose to keep the Center of Gravity in place with this very light engine. This is SIG's recommendation. Plus, the pressure nipple on the carb body would hit the mount if the engine is pulled back more towards the firewall. (And I do not want to butcher the mount by cutting its cantilevers shorter..)

I hope the glass-filled engine mount is rigid enough to prevent vibrations in this cantilever type setup where the engine is moved away from the firewall. A bit unusual in my build practice, but lets hope the mount which was designed for larger engines will stand firm without vibrations.

I am still wondering what sort of dope I will use to seal the firewall and the engine cowl, even though this time I will try an O-ring pulled on the cylinder neck to stop castor flowing down from the muffler into the cowl...It will certainly not be perfect but at least keeps most of the oil out.

The spray type enamels and varnish they sell in hobbyshops here do not seem to perfectly resist nitro fuel....in my experience so far

Should it be an acryl based varnish, or as someone said a 2-component resin is the right dope? I would like to avoid fiddling with home blended 2 component stuff that cures soon and the leftower winds up in the waste bin. I prefer spray type materials that is just used right away and put back on the shelf for the next build, after you are done.

Maybe a transparent enamel sold in auto parts shops is the solution? Is that not too heavy?

[OVERLORD]

Great progress Andras, that is looking perfect!

If you want to use varnish to seal the engine bay, use polyuretane varnish. It is sold in spray cans or in pots to brush on. When using paint, also PU paint is needed. Car paint is usually acrylic and does not resist to fuel except the paint made for covering engines and exhaust pipes. That is PU paint. I used that on my free flight models and it doesn't move at all. I first covered the wood with normal dope 2 or 3 coats with sanding in between and then covered all with paper. Then I sprayed on the paint. You can do without the paper but the dope is needed I think to strenghten and harden the balsa.

This is the paint I used:

https://www.motip.com/products/motip/automotive/universal-paints/heat-resistant-lacquer/

The colours are limited though. What you can do also is paint it with acrylic and once dry varnish with PU varnish. When doing this you better use the same make to avoid surprises. Sometimes the varnish tend to dissolve the paint layer.

Hoe this helps.

Lieven

[balogh]

Thanks Lieven, great help. I will look for the polyurethane varnish in sprays bottles, possibly transparent. Any idea what its everyday use is? Should I find it in car parts shops, paint shops or usual building supplies shops like OBI (I am not sure if OBI is present in France)?

[OVERLORD]

You can find it in the DIY store. It is used for wood furniture. Make sure the can mentions PU and certainly not acrylic, or resistant to fuel or alcohol.

The Motip heat resistant paint also comes in clear varnish.

[MauricioB]

I started the build this weekend and completed the wing and the the firewall with the engine mount.
Like often I replaced the stock balsa leading edge with a hollow carbon 6mm*6mm square rod to better resist the hard terrain landings. The carbon rod adds 24 grams extra to the weight but I will save this by e.g. using a balloon tank instead of the clunked Sullivan tank SIG recommened, and other measures.




The ailerons are yet to be added, now I continue with the build of the fuselage.



The Tee Dee 09 sits far ahead in the nose to keep the Center of Gravity in place with this very light engine. This is SIG's recommendation. Plus, the pressure nipple on the carb body would hit the mount if the engine is pulled back more towards the firewall. (And I do not want to butcher the mount by cutting its cantilevers shorter..)

I hope the glass-filled engine mount is rigid enough to prevent vibrations in this cantilever type setup where the engine is moved away from the firewall. A bit unusual in my build practice, but lets hope the mount which was designed for larger engines will stand firm without vibrations.

I am still wondering what sort of dope I will use to seal the firewall and the engine cowl, even though this time I will try an O-ring pulled on the cylinder neck to stop castor flowing down from the muffler into the cowl...It will certainly not be perfect but at least keeps most of the oil out.

The spray type enamels and varnish they sell in hobbyshops here do not seem to perfectly resist nitro fuel....in my experience so far

Should it be an acryl based varnish, or as someone said a 2-component resin is the right dope? I would like to avoid fiddling with home blended 2 component stuff that cures soon and the leftower winds up in the waste bin. I prefer spray type materials that is just used right away and put back on the shelf for the next build, after you are done.

Maybe a transparent enamel  sold in auto parts shops is the solution? Is that not too heavy?

Very good work András !! .... what a nice pleasure is the construction of a model, where our brain and heart is launched, that magic mix of technique and passion that makes us dream and fly from the beginning.
I will accompany you, my friend!

[balogh]

Thank you Mauricio. We had a beautiful autumn weekend here so I went to the field to fly the 051 powered RC Toucan but still had some time to continue the Wonder build project. I am almost done with the fuselage and this is what they with the wind look like:





I will continue next week when my work allows me to.

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