Re: Starting a G-Mark .03

MauricioB Tue Oct 02, 2018 10:21 pm

scouring the web I found this video Brad, use a 5 x 3 of Cox, what do you think ??

1/2A Nut Tue Oct 02, 2018 10:59 pm

Thank you

, i have seen that video before, anytime you use a heavy prop or one with large disk area or
wide cord or thick airfoil it will throttle ok. The top end rpm suffers of course, it really is up to your plane and
type of flying you wish to enjoy.

I am still working on the G-Mark RC carb with the TD .020 the carb is simple in design, today I tested it but the
aluminum carb body came loose creating a air leak reduced the rpm. Normally it runs very steady. I really need
a better RC carb, one with a bit more bore on the barrel with a air bleed.

Published on Oct 2, 2018

Testing GMark carb add on with Nelson plug.
Quick run it is very loud with this kind of rpm open exhaust.
I did a couple of quick runs with it the carb body came loose
Shown 29,392 rpm / 125 mph pitch speed /6.4oz thrust can spin the
3.6x4.5N at 30,604 rpm /130.4 mph /7oz thrust! Bob Mattes FF reworked
TD .020 with a GMark carb and GG backplate /Valentine .020 bullet spinner.
Needs a bit more prop for safer realistic unloaded rpm around 34k for flying.

Here noticed I moved the engine over to fresh wood:
At 30k+ rpm the engine thrust was up to 7oz it ripped the screws out of the oiled soaked wood grain and the engine flew off the stand.
With the engine secure it sang to 30,604 rpm!

1/2A Nut Tue Oct 02, 2018 11:12 pm

Mauricio,
I have noticed a change in the point system when I give you a thumbs up

it only gives you 1 point.
Normally when I give you thumbs up you get 3 points. So today gave Kris a thumbs up it gave him 5 point increase.
I doubled checked and gave him another thumbs up on a different post and it showed 5 points again so then went to a
different post of yours and gave you a thumbs up to double check it only gave you 1 point! I have noticed I only get 1 point now too.
I use to get 3 points. It looks like our reputation point value is being suppressed for some and not for others. Shocked

GallopingGhostler Tue Oct 02, 2018 11:57 pm

1/2A Nut wrote:Thank you , i have seen that video before, anytime you use a heavy prop or one with large disk area or wide cord or thick airfoil it will throttle ok. The top end rpm suffers of course, it really is up to your plane and type of flying you wish to enjoy.

I noticed that it had a lower top RPM with the 5x3 prop, not much different than when I was using a Top Flite nylon 5.25x3 prop on a Cox .020 Pee Wee powering a 27" clipped wing Schoolboy back in the early 1970's. With the amount of drag by that larger 1/4-A aircraft, I still got the same air speed as I did with the Cox 4.5x2 prop, but with about an additional minute of flight time.

Sometimes going to a slightly larger prop with lower RPM's does have its benefits.

1/2A Nut Wed Oct 03, 2018 12:10 am

Yes very true! Thumbs Up

I too have purposely used a bigger prop just to reduce the fuel charge going into the engine less rpm
less cycles of fuel going to the top of the piston. The TD at 30k rpm slurps down a 1oz tank fast! Wink

MauricioB Wed Oct 03, 2018 11:03 am

1/2A Nut wrote:Mauricio,
I have noticed a change in the point system when I give you a thumbs up it only gives you 1 point.
Normally when I give you thumbs up you get 3 points. So today gave Kris a thumbs up it gave him 5 point increase.
I doubled checked and gave him another thumbs up on a different post and it showed 5 points again so then went to a
different post of yours and gave you a thumbs up to double check it only gave you 1 point! I have noticed I only get 1 point now too.
I use to get 3 points. It looks like our reputation point value is being suppressed for some and not for others.

Friend

So ... There is something that is not right.
Maybe an error in the system. It's a shame, if so, then the scores would not be real then! Huh...

Maybe you have to tell him or tell Jacob!

1/2A Nut Wed Oct 03, 2018 2:58 pm

Mauricio I will monitor further first. Perhaps it will change.
Just gave you a thumbs up still only 1 point Sad

GallopingGhostler Wed Oct 03, 2018 3:16 pm

MauricioB wrote:
1/2A Nut wrote:Normally when I give you thumbs up you get 3 points. So today gave Kris a thumbs up it gave him 5 point increase. I doubled checked and gave him another thumbs up on a different post and it showed 5 points again so then went to a
different post of yours and gave you a thumbs up to double check it only gave you 1 point! I have noticed I only get 1 point now too.
I use to get 3 points. It looks like our reputation point value is being suppressed for some and not for others.
So ... There is something that is not right. Maybe an error in the system.

I don't think so. When the system changed, the Thumbs Up

became a Like button. I'd see a post I like then click Thumbs Up

. Sometimes I don't post, I just click Thumbs Up

. I think what you all are observing is others clicking like about the same time, because we all have notices turned on. But lately, I haven't been doing much Thumbs Up

clicking at all. Paranoid

It's probably just coincidence that several of us has been clicking at around the same time. Computer Issues

1/2A Nut Wed Oct 03, 2018 3:28 pm

No it has changed only in the last few (4 ) days use to be 3 points now only 1 for some btw your now a 1 as well.

MauricioB Wed Oct 03, 2018 4:02 pm

Friends, I'm interested in a Graupner 5 x 2 propeller on a trial basis.
Does anyone know where I can get it in the US?
Here is a notice but it's from England:
http://www.modelshopleeds.co.uk/catalog/product_info.php?products_id=4500

I have seen this propeller work in a Pee Wee .020, (I leave the video), I would like to try it in the G-Mark .03
As you know, we are experimenting and all information and experiences are very useful!

1/2A Nut Wed Oct 03, 2018 10:02 pm

Graupner Nylon 2 Blade Propeller 4.8x2" (12x5cm)

The propellers are made from glass-fibre-reinforced nylon material and are incredibly strong.

Specification:
Diameter / Pitch [cm]: 12x5cm
Diameter / Pitch [inch]: 5x2"
Colour : grey
Sort: Rigid Props
Rotating direction: R
Piece / Pack: 1
Diameter / bore [mm]: 2,5 mm

£2.99
http://www.nexusmodels.co.uk/graupner-nylon-2-blade-propeller-4-8x2-12x5cm-1316-12-5.html\
https://www.hobimaailm.ee/et/a/propeller-12x5cm-5x2-graupner

Computer Issues

MauricioB Wed Oct 03, 2018 10:06 pm

1/2A Nut wrote:Graupner Nylon 2 Blade Propeller 4.8x2" (12x5cm)

The propellers are made from glass-fibre-reinforced nylon material and are incredibly strong.

Specification:
Diameter / Pitch [cm]: 12x5cm
Diameter / Pitch [inch]: 5x2"
Colour : grey
Sort: Rigid Props
Rotating direction: R
Piece / Pack: 1
Diameter / bore [mm]: 2,5 mm

£2.99
http://www.nexusmodels.co.uk/graupner-nylon-2-blade-propeller-4-8x2-12x5cm-1316-12-5.html

If friend I saw this notice but it has zero (0) stock and it is in england ... well nobody has this in the USA?

1/2A Nut Wed Oct 03, 2018 10:11 pm

This is in stock:

https://modelisme-buggy-vintage.com/epages/329b65de-5b3f-453b-b4e2-67465aba5323.sf/fr_FR/?ObjectPath=/Shops/329b65de-5b3f-453b-b4e2-67465aba5323/Products/%221316/12/5%22

And 1 here:
https://www.hobimaailm.ee/et/a/propeller-12x5cm-5x2-graupner

I have found none in the USA.

MauricioB Wed Oct 03, 2018 10:19 pm

1/2A Nut wrote:This is in stock:

https://modelisme-buggy-vintage.com/epages/329b65de-5b3f-453b-b4e2-67465aba5323.sf/fr_FR/?ObjectPath=/Shops/329b65de-5b3f-453b-b4e2-67465aba5323/Products/%221316/12/5%22

And 1 here:
https://www.hobimaailm.ee/et/a/propeller-12x5cm-5x2-graupner

I have found none in the USA.

We have found out and there are about 25 euros of shipping ... it is not unreasonable, I prefer to invest in Cox USA.
Tell me Brad, you who know a lot about drone propellers, some similar?

1/2A Nut Wed Oct 03, 2018 10:59 pm

E Flite 3.75x3 is good for fast planes.

Published on Mar 5, 2016
TD .020 / E Flite 3.75 x 3 Prop / Best Level Pass- 29,554 RPM / 84 MPH / Throttle Sleeve
Static at launch 22,529 / 4.6oz thrust / 64mph / 36w / per prop calc
Best dive down wind out of 3 video's / 31,419 rpm / 89.3 mph
RTF 5.3oz - Actually has unlimited vertical / 35% Nitro / Run time 9.06 mins

https://www.towerhobbies.com/cgi-bin/wti0001p?&I=EFLA2227&P=FR&gclid=EAIaIQobChMIsMWE2PLr3QIVGozICh0bhA0PEAYYASABEgL9w_D_BwE

Published on Apr 3, 2016
Lil Speedy TD .020 / E Flite: 3.75x3 / 31,257 rpm / 148.37 km h / 92.19 mph
Another good reading from a pass about 40ft up / 153 km h / 95mph
Winds 6 to 8 mph. 80 F / Per Doppler and audio app best passes
Needle valve was dialed in better on this flight made more rpm.

This is a good prop less speed but good thrust: 4x2.8
https://www.rcnhobby.com/gemfan-4x2-8-4028-carbon-fiber-propeller-250mm-multirotor-cw-ccw-html

Surfer_kris Thu Oct 04, 2018 12:55 pm

MauricioB wrote:Friends, I'm interested in a Graupner 5 x 2 propeller on a trial basis.
Does anyone know where I can get it in the US?

I quite like the graupner props in general, they were made in Germany and those were the props that I grew up with. The 6x3 ones are good size for most timid .049 engines, like the Babe Bee, gives good thrust and fuel economy.

The 5x2 (mine is barely 4.8" I think) has a thicker airfoil compared to the cox ones, plus the longer length, so the load is quite a lot higher. They do add some inertia and makes for a little easier hand-starting, but they are no revolution for the G-mark .030. In fact I started out using the graupner prop for the first runs on the G-mark, but the engines ran hot at full throttle so I switched to the Cox 4.5x2 instead. The engine still runs too hot though so perhaps the graupner was a just as good match after all...

They are good for free-flight full throttle style or maybe CL, but for RC the pitch is too low I feel. I used one on a small Cub and a peewee with exhaust throttle, but ended up using full throttle most of the time. I wouldn't recommend spending to much money on getting some, they are certainly no revolution and the design probably hasn't changed at all during the last 40-50 years or so...

Here is a comparison to a cox 4.5x2 prop:

MauricioB Thu Oct 04, 2018 1:32 pm

Surfer_kris wrote:
MauricioB wrote:Friends, I'm interested in a Graupner 5 x 2 propeller on a trial basis.
Does anyone know where I can get it in the US?

I quite like the graupner props in general, they were made in Germany and those were the props that I grew up with. The 6x3 ones are good size for most timid .049 engines, like the Babe Bee, gives good thrust and fuel economy.

The 5x2 (mine is barely 4.8" I think) has a thicker airfoil compared to the cox ones, plus the longer length, so the load is quite a lot higher. They do add some inertia and makes for a little easier hand-starting, but they are no revolution for the G-mark .030. In fact I started out using the graupner prop for the first runs on the G-mark, but the engines ran hot at full throttle so I switched to the Cox 4.5x2 instead. The engine still runs too hot though so perhaps the graupner was a just as good match after all...

They are good for free-flight full throttle style or maybe CL, but for RC the pitch is too low I feel. I used one on a small Cub and a peewee with exhaust throttle, but ended up using full throttle most of the time. I wouldn't recommend spending to much money on getting some, they are certainly no revolution and the design probably hasn't changed at all during the last 40-50 years or so...

Here is a comparison to a cox 4.5x2 prop:

It's very good information, thank you Kris!
I was testing the Cox 5 x 3 and the engine to go very well even with a very good idle, as Brad says, as the engine is running will go on and will achieve an idle perhaps peer to the numbers he (Brad) has obtained, that is to say 4600 rpm with a 4 1/2 x 2, for all this I was interested to see that such a VAT the 5 x 2 of Graupner, imagining that it would be a good initial helix for the first flights of the engine.
But since it is not possible to obtain it in the EE. UU., The shipping costs from Europe make it not worth buying a couple of them to do the tests.
I will then continue with the Cox 5 x 3 and then with the Cox 4 1/2 x 2 to enjoy all the ranges of engine running.
On the other hand it is notorious for its temperature that fully coincides with his comments (Kris) and Brad, I wonder why they would not have made a glow plug with cooling fins, that would change the temperature of the engine a lot.

gkamysz Thu Oct 04, 2018 5:51 pm

[quote="Surfer_kris"]

MauricioB wrote:The 5x2 (mine is barely 4.8" I think)

The Graupner Super Nylon were design in metric units. So, if you look at the 5'x2" it's 12x5cm or actually 4.7"x2". The inch sizes are rounded, and this causes big deviations in expected loads and power calculations at times.

MauricioB Sat Oct 06, 2018 10:10 pm

gkamysz wrote:
Surfer_kris wrote:
MauricioB wrote:The 5x2 (mine is barely 4.8" I think)

The Graupner Super Nylon were design in metric units. So, if you look at the 5'x2" it's 12x5cm or actually 4.7"x2". The inch sizes are rounded, and this causes big deviations in expected loads and power calculations at times.

Excellent data friend! Hand Shake

Surfer_kris Sun Oct 07, 2018 2:59 am

Yes, being a german company they seem to have chosen to use accurate metric values and rounded off the inch values on their markings.

MauricioB Tue Oct 16, 2018 4:33 pm

I have noticed a slight displacement of the carburetor, although it is adjusted, with slight force one can move it as indicated in the photo, so I decided to see what the issue was about. I even want to avoid any failure in the aspiration of the motor in case that were the case.

When I finally removed the latch from the pin, I was able to remove the carburetor and observe that there is a large hole compared to the diameter of the pin, which causes that unwanted movement to exist to my liking.

MauricioB Tue Oct 16, 2018 4:37 pm

Then thanks to the marvelous lathe that Mario gave me, I started to manufacture a bushing with an adequate base to eliminate the movement.

MauricioB Tue Oct 16, 2018 4:40 pm

present the motor, to confirm if the measurement was correct.

MauricioB Tue Oct 16, 2018 4:42 pm

this way the "extra" support bushing is placed

MauricioB Tue Oct 16, 2018 4:45 pm

take advantage of the disarmament and put a gasket between the carburetor and the body of the carburetor, this is a way perhaps exaggerated to avoid leaks! ... but it is worth the attempt of prevention!

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