mirce

Tod, thank's for informations...

Mirce

G-Pete

Because the DA85 is a superior engine with an excellent power band
Bad mid range and sloppy sound comes from the muffler and needle settings.
So far DA had only one upgrade to that engine (redesigned piston)
Well, DA is the only one manufacture who does that - upgrade your engine for free to the newest version. Last update on the G-62 was 1997 when the the newer WT series carburetor came out

Weight? the G80 is only 1.5 pounds heavier and swings only a 24 inch prop, the DA swings a 26. The zenni is more expensive and uses more fuel. What is good on the zenni, it is a good base for a race engine and likes to go around 10K rpm on tuned pipes, porting, light pistons and 18mm dual carburetors with long velocity stacks. But that is not suitable for warbirds (most think so), they should fly close to stall speed to look "real" - but this is another story.

To say the G80 is a good engine - alright, but better then the DA85- NO!

crashproof

Not worth discussing with you, thats like trying to climb a muddy hill in the rain backwards.

OldScaleGuy

My Feedback: (2)

Discussion is good. It is how we all learn. I thought very stongly about the GT-80 for this plane. It is a great motor. However, i compete in scale and did not want to cant the engine inside the cowl. The one Z Hellcat i saw with a GT-80 flew great but he left the engine sitting level and you could see the spark plug boots pushing against the inside of the cowl. A buddy of mine has a DA-85 in a Super Cub and to me it sounds good to me, i don't know what muffler he is using and he absolutely loves the engine.

crashproof

Well in truth the DA 85 weighs 4.3 lbs the Z GT 80 weighs 7.7 lbs (taken from chief AC ) You will need the weight or you can melt a bunch of lead and place it on the FW. I believe in ease and reliability. Just do a search in the engine forums and you will see what is being sent in for repairs. I wish you good luck with the Cat.

crashproof

GT 80, Ziroli Hellcat, 24/10 prop. http://www.youtube.com/watch?v=Y-GsfoYd3Mk

OldScaleGuy

My Feedback: (2)

That is great.
I wonder if canting the engine, say 10:00 and 4:00 would effect the performance?
Now excuse while i go find the glue and get busy....

Detlef Schmidt

Hello dear HELLCAT fans,

I flew my HELLCAT with G80 and last summer I installed a MOKI 150.

I can promise that G80 is definitively THE choice for the HELLCAT.

I canted the engine to 10.00 without any problems or effect and used a stainless steel exhaust from www.toni-clark.com

It swings a Menz 24-10 with 6.300 or Engel 24-10 Carbon-prop with 6.600 rpm.

Great performance, great sound and completely inside the cowl.

Regarding the HELLCAT the G80 wins clearly versus DA85 !

Already with G80 I added 4.4 lbs lead in the cowl !

Here you can see my HELLCAT and the one of a friend from Switzerland, both powered with G80:

http://www.youtube.com/watch?v=lPQZJTZiTAk

http://www.youtube.com/watch?v=0E47B_ZnH4w


best regards and happy landings,

Detlef

wulf190

My Feedback: (19)

Great looking install Detlef. Very clean. I like the simplicity of the throttle servo location and, thus, the connection to the carb as well.

G-Pete

Well, DA85 or G80 - still not enough to swing the scale propeller. I think more like of an 137cc single short stroke (15 pounds), that will swing the scale 29 inch 3-blade propeller Tricky but possible.

G-Pete

nah.......

G-Pete

...like on Hamburger Hill May 10–20, 1969?

Detlef Schmidt

@wulf190:

Hi Mike,

I m happy that you like my installation. In the same position as the throttle-servo on the other side of the mounting-plate sits the choke-servo and has a similar connection to the lever at the carburator.

@ G-Pete:

Wow 137 ccm single-engine ! Will swing a scale-prop for sure, but how about vibrations ?

Once i used a 100 ccm single on a MUSTANG with fibre-fuse and it was shaking and vibrating the plane badly. So bad that I got cracks in the strucutre after few flights.

By the way: Did you ever test a 29" prop on Ziroli HELLCAT ?

29" prop will touch the ground during operation !!!

The gear of the scale model is shorter than original (talking about my ROBART)

26" (with risk maybe 27") prop is maximum for sufficient ground clearance during take off and landing.



best regards from snowy Bavaria

Detlef

wulf190

My Feedback: (19)

Great Detlef...even the choke servo in there as well. I'm not fond of clutter up front, and the less space a huge block of lead takes up makes this all the better for me. Seems like a healthy block(s) are going to be fitted up there, even with the fatter engines. But, at least with ignition engines, you can stuff a nice heavy ignition battery pack up front as well.

G-Pete

Detlef, the vibration just comes from a unbalanced motor and/or propeller. Most modelers do not balance the propellers or properly. Almost nobody balance the prop-hub, they not even know how.
One solution is the soft mound - but this good for the eye but not good for the airframe. The problem is the Oscillation when they become harmonic. Therefore soft mounts are good for smaller engines to avoid high frequency material disturbance - but for and lager motor I would not recommend that.
On the other hand some engines are so bad crank balanced, everything needs to be lock tided.
The next problem is the unstable circulation of the propeller tips - this cuts down on performance. Zinger propellers are so popular because they have flat tips which takes care of some irregular airflow - this results in more noise.

To the size of the propeller- Detlef, I build my airplanes scale that means my landing gear will be scale and my propeller (if possible) will be scale. I fly 25 inch four blade on a TF P-47. Only 5 degree over Datum is there allowed. At the final you flare the airplane anyway, it's like more 3-5 degrees positive at touchdown. To land scale, F6F, you have to bring her down in a 3-pointer (tail hook!)

Here on that drawing you see how much the airplane has to go over datum to get a prop strike. I do my homework before I say something.

I will not use the Robart gear, Darrel will cut me the right size and scale appearance. I do understand your concerns about the prop strike, I watched your video clips and saw the your home field. Well, I do not fly at grass fields - call my pampered fine. My home field has a 550 feet paved runway. I care more about scale then weight...heavy birds fly better - feel better = more fun. They glide not very well, but if I want to glide then I build a glider and not a warbird.
Full scale F6F manual Quote" If the stall spin occurs below 4500 ft jump!"

I was listening to SWR3 this morning - the Preiss got hammered with snow, now I live in Texas for 11 years this was the (2009) first Christmas with snow.
Alles klar auf der Andrea Doria! Bis speater...Ade (badenser).

Detlef Schmidt

Hi G-Pete,

yes indeed the "Preiss" has big problems with the snow but here in Bavaria we love the snow !

But to be honest we have got not so heavy load from "Daisy" as the "Preiss".

Keep us updated about your HELLCAT project - will be intresting.

If you like to build it very scale install a MOKI 150.

I run this engine since autumn in my HELLCAT and I love it.

best regards

Detlef

P.S.: Say best wishes to Darell from SIERRA - for sure he will remember my P-38 ;-)

Scott Prossen

Hey Detlef,

Glad to hear about your Hellcat and the Moki 150. I'm very partial to the Moki as well. Can you tell me what prop you use on the Moki/Hellcat? Do you have any pictures of the engine mounting? How about some video of the 150/Hellcat combo? We would all love to see that! I'll be doing the same this spring to a Z-Hellcat that I bought that currently has a GT-80 in it. I love the GT-80 but the Moki is so much better for me. Can't wait[sm=teeth_smile.gif].
Thank you in advance,

Scott

OldScaleGuy

My Feedback: (2)

You fella's sure have me considering the GT-80 for mine and now am leaning that way.
Detlaf, your engine installation looks great. In the front view picture (below) which could be misleading, i understand, it looks like the spark plug boots are still going to be "pushing" on the inside of the cowl. Can you help me understand better what the condition is? As far as turning a scale prop, that is not a consideration in scale competition. We must have a scale prop for static judging but most change the prop to a "flying" prop after static. To match a scale prop to a scale plane sounds like a task that would really reduce your options of what you could build and the plane/engine combinations. Each to their own on that, that is whats keeps all of this interesting.

Detlef Schmidt

Hi "OldScaleGuy",

thanks for your compliments !

Regarding your comments about scale props I agree 100% !!!

Regarding my GT-80 installation the picture is definitively missleading becasue of the perspective.

The spark plug boots have about 5 - 6 mm clearance to the inside of the cowling.

I was using a 60 mm prop hub but if using a short hub (30 mm or 40 mm) I am not sure if there is still enough clearance as the cowl diameter narrows to the front end.

The hub which I was using is available as an option from www.toni-clark.com

If you like to stay with the standard hub (40 mm - if I remember correctly) a 20 mm spacer might do the job as well...


best regards

Detlef

OldScaleGuy

My Feedback: (2)

Detlef, thank you for the confirmation. I tried earlier to download the catalog from the Tony Clark web site but couldn't get it to work. I will try it again. You know that 60mm works so i will definately go with that. Sure wish i could afford the Moki.... []

Detlef Schmidt

Hi Scott,

unfortunately we have not taken a video of my HELLCAT with MOKI 150 yet, but in spring I will ask one friend to take one and I will publish it here.

Regarding props I have tested some options and the best was 2-blade 26x14 scale-blade from www.sep-ls.de

My MOKI 150 swings this prop with 5.100 rpm on the ground.

I tested as well the 3-blade 26x14 of SEP and Engel supersilence but with both props the revs on the ground were less than 4.500 rpm and this gives not enough performance, problems with throttle response between 3/4 and full throttle and problems with overheating of the MOKI as well.

The problems of throttle response are less with very new MOKI 150 engines as MOKI changed the inlet manifold end of 2009.

Due to smaller diameter airspeed is higher in the inlet-system and repsonse is better.

I have got exchanged my "old" MOKI and will test the new in spring.

As well in spring I will test a 25" 3-blade SOLO because it looks so good but the 2-blade SEP costs about 40.- EURO, the 3-blade about 80.- EURO and the price of the SOLO you know....

Anyway if you keep the revs between 5.000 and 5.200 rpm on the ground you might be happy with any prop of your choice.

2-blade is a little better regarding performance (efficiency) as the 3-balde, but 3-blade looks more scale, but as you mentioned already: Flight performance beats scale-look in flight condition.

By the way: Do not forget to mount balsa plates between the cylinders in order to lead the airflow to the cooling-rips of the cylinders - otherwise engine-failure due to overheating is guaranteed !

To ensure the extraction of the hot air from the cowling I opened 3 cowl-flaps at the bottom of the cowl.

In the moment I am curious to close the middle flap and to make the 2 side -flaps functional as a tribute to respect scale-issue, but the condition of my engine is priority 1 in my opinion !

Another idea would be to extend the upper cowl-flaps or to make it funtional to open it wider, but I was to lazy to do so.

Maybe it will work without any additional cowl-flaps but the balsa plates between the cylinders you will need for sure !

I made one test flight without the plates and without the additional cowl-flaps and the engine quitted after 6 minutes.

Until I run the engine with the plates and the additional cowl-flaps I never had problems not even after 15 minutes flight-time in hot summer-conditions.

Some guys are suggesting to use an electric fuel pump but I run my engine without.

I did some tests and there was no difference with or without fuel-pump as far as the fuel pipe from the tank is max. approx. 60 - 100 mm

Please find the pictures attached.


best regards

Detlef

Detlef Schmidt

Instead of videos for the moment I can only provide some inflight pictures...

Sound and motion might be up to your imagination - but its awesome anyway

Scott Prossen

Detlef,

Very nice pictures and info. Thank you for that. Have you looked through the following thread? http://www.rcuniverse.com/forum/m_89..._1/key_/tm.htm

It has lots to offer in terms of answers for any questions you might have about the Moki.

All the best to you,

Scott

OldScaleGuy

My Feedback: (2)

Can one of you fella's actually measure the GT-80 width with the plug boots on? Horizon's specs. indicate that it is 270mm wide. That looks/sounds a bit narrow.

Detlef Schmidt

Hi,

please see the drawing attached.

Those sizes are correct .


Best regards

Detlef