3D Joy

Around 1.5 lbs...

airwayman

My Feedback: (2)

Cans, cans, cans. Where can I find info on these devices? I need to make some muffler decisions on two ZDZ 80 powered planes in the next month or so. Thanks, JB

airwayman

My Feedback: (2)

Anyone have operating experience with a 3W80 vs. a ZDZ 80? (Not the new J model, just the current model). Do they have similar power output?

3D Joy

My ZDZ 80 RV with the canister above cut 1" shorter spins the Mejzlik 26x10 at 6700 RPMs at sea level or just about. This thing 3Ds and IMACs my 24.2 lbs Extra with ease.

The 3W 80 IS a new model I think. You should compare both NEW engines to be fair.

airwayman

My Feedback: (2)

The 3W 80 IS a new model I think.

No, it's at least 8 yrs. old but new to me. It came from the factory with red cylinders. Gerhard says it's too old to be a Quique engine and the 80 cc series has been replaced with the 106. He thinks it's a factory "hopped up" version. A friend gave it to me; it looks almost brand new so I think I'll try it. Just wondering if anyone had experience with the 3W80B2 engine. I have a new ZDZ 80 RV that I could use. Just wanted some numbers, if anyone had them, rather than do all the firewall/cowl/muffler work and then be disappointed.

Scoubidou

My Feedback: (17)

Hi 3d joy!
Have you had a chance to put a Mejzlick 27x10 on your set-up? I do not know if this prop has the same thrust of Mezjlik 26x10?

26x10 at 6900-7000rpm static should be noisy?
Daniel

3D Joy

I was referring to the new 3W80 single. Every single of the same displacement of a twin, everything else being equal, has more power than the twin. Every single has more vibration that a twin also --> compromise. Every single is cheaper than twin.

Hi Daniel,
I did not try the 27x10, which is said to have about the same load as the 28x10. I did try a MenzS 26x10 and did not like it. Throttle response is vastly improved though but it seems the Mejzlik pulls better overall AT SPEED (IMAC). For 3D, only the fact that throttle response is improved is a very good thing IMO but I don't want to change props every 3 flights so the Mejzlik is back on the plane.

As for noise, my 26x10 turns 6700 on the ground and in the air, unless I really want to be noisy, the prop does not rip. And the MenzS rips a bit easier but that is not very bad.

I am not sure I would prop the new ZDZ80 any smaller than the 27x10 but for the one I have (older version), I don't think there are much better props than the one I use. If I had a pipe, which could get me close to 7000 on the ground, I would still use the 26x10 and get better trhottle response from a lightly loaded engine.

branded

My Feedback: (9)

I dunno, I have two of the "old" ZDZ80's.....I admit to not reading all the posts in this thread but one post I did read intimated that a "Scientist" designed the new ZDZ 80...

So I pose this question to the 'Scientist"...

WHY DO YOU USE MULTI BOLT PROP HOLD DOWN WHEN SINGLE BOLT WOULD SUFFICE????

rmh

c'mon now, be serious.
just for openers -the amount of compressive force from the six 4mm bolts, far exceeds that possible with the single bolt.
To restate this :
the torque required on the the single bolt , must equal the additive torque applied to the six bolts for the applied pressure to be equal.
To simplify this test- start with a threaded center bolt . Pull it very tight.
Now go around th 6 bolt pattern with moderate pressure.
Now recheck center bolt.
Is it loose?
Try this on a new wooden prop -the applied pressure difference will become obvious.

Flip and Fly

Thats right Dick, and then re-tighten the center bolt again and notice how the 6 4mm bolts have become loose

Dangerous Dan

My Feedback: (1)

I have flown 140 flights on my WH 28% extra special with BME 50 Single Bolt.. It has never budged an inch, Extra bolts would be a waist of time and weight.

Flip and Fly

In my mind the extra security with 6 bolts on larger motors is not a bad thing.

On my ZDZ 80 I run the center bolt tight, but dang it all, when I tighten the center bolt, the 6 4mm bolts loosen up, and when I re-tighten the 4mm bolts the center bolt loosens up. Kind of like a dog chasing its tail!

So I go for a happy medium between the two

rmh

Let's see -if one bolt breaks -which setup still operates --

excaliber

Two things here guys.
1, with a wooden prop you are compressing wood fibers each time, equals loosening of he bolts.
2, using 6 4mm bolts plus the nomal center prop hole also (in my opinion weakens the hub area,saw one split while starting an engine an hit the pilot in the neck, only grazing him)
3, There is also a tracking potential with a 6 bolt hub if not tightened properly.

mrbigg

My Feedback: (21)

i've seen a 150cc equipped plane, shear all the bolts off in flight, throwing the carbon prop. prop was never found.

flier

My Feedback: (7)

Look at full scale props one time, bet you see more than one bolt.
Same holds true with wood and metal props.
Each is set at the proper torque and safety wired.
All these backyard engineers and there theories make me laugh.

triangle

My Feedback: (3)

then what is the torque for the 6 bolts and the center one??

flier

My Feedback: (7)

The engine Manuf. should supply this info in the manual.

rmh

What would you think it should be?
This is really one of those questions that can be "interpreted" differently .
What does the local tire guy use as good torque on your new aluminum wheels - 7/16" stud ? six of em?
What does your old Chev manual say about 5/16" std manifold bolts? Or the fine thread engine bolts?
On our engines, what is the thread and diameter in question?
On ZDZ 80 it is 10mm on center stud (prop centering stud) and 4mm' on each of six --except on 40-and 50 cc no center threaded stud.
On a DA 100 and a 3W- there are six, 5mm bolts . no center threaded stud
Because wooden props constantly compress -the figure is a moving target -that needs to be constantly inspected .
My ROTO and my EVO (smaller 26cc engines ) - one has a single 8mm stud and the other a 10mm stud. each engine is holding the same prop load -so do you use different torque on the 8mm than the 10mm????
The BME110 has a single stud of -similar diameter to 10 mm -(guessing) but more prop load .
what is correct torque
- looks like there is no finite number so let's hear some guesses and reason for the guesses.

bpryor

My Feedback: (45)

Hi flier,

Since no engine manufacturer has ever supplied torques with the engines I've purchased, and since you are obviously an expert on the subject, will you please let us know what torques you use?

Thank you.

Oh, BTW, if you hadn't noticed that there's a bit of difference between the size of our props and the stresses involved compared to full-size planes. There are a lot of things that are different between full-size planes and our little models because of size and scale factors, such as I haven't seen many full-size planes using balsa in their construction lately. It really doesn't make much sense to compare full-size and model planes as far as contruction, fastening, or stresses involved.

flier

My Feedback: (7)

bpryor,
Your sarcasm does you justice.
Every thread size has a torque rating, don't believe me, ask a mechanical engineer.
The engine manufacturer will list a preferred method for prop installs.
If using wood props, you'll have to recheck the tightness of the fastener(s) more often.
IMHO These should be checked before each flying section, along with the prop.
It just makes good sense to do so.
Using only a single nut, I'd also use a jam or locking nut too.
As Dick pointed out above, on the multi bolt hub, braking one or two and see witch is still flying.
Redundancy of the six bolt hub is not that much weight, for the safety returned.

bpryor

My Feedback: (45)

Thank you, I couldn't resist. I was just responding to your friendly post above. ("All these backyard engineers and there theories make me laugh.") BTW, if you knew who some of these "back yard engineers" were that are posting here, you'd be feeling pretty silly.

...and I am not arguing that torquing would not be the preferred method, but you stated that manufacturer's provide these numbers, and I don't have those numbers, nor have I every seen any, but since you must have them, it would be great if you would post them for everyone.

rmh

I was really looking for opinions on torque - not on people -
All GOOD bolts do have tested ratings . ASME likely has a large chart on recommendations.
But for our use - it would be a bad idea to even get close to these ratings
I remember on the flywheel bolts of my 327 Chev -the book said (I think) 35 lbs each -and I was ready to put 90 each on em.
Torqueing bolts is not as simple as it seems - If you tighten a dry .cold bolt -it feels much different than a warm lubricated assembly.

but for conversation sake - let's say 35 ft lbs on a single 10mm prop stud - using a hardened nut (?) against a hardened washer .
should that do it ?
If so -then 35 ft lbs torque- ifdivided by 6 (six smaller bolts) -would only need 6 ft lbs each
Right?

flier

My Feedback: (7)

Then why is it your trying to reinvent the wheel?
Men much smarter than you or I have all ready figured this all out.

Why do you say this Dick?
Does it not make sense to tighten the bolt to it designed capacity?
If the design enigneers say that a specific size of bolt was needed to hold/retain "X" load.
If a smaller bolt would have done the job, they'd have used a smaller one.


[quote]ORIGINAL: dick Hanson

Torqueing bolts is not as simple as it seems - If you tighten a dry .cold bolt -it feels much different than a warm lubricated assembly.

[quote]

All torque ratings are for dry threads.

flyinrazrback

My Feedback: (69)

So is anyone flying one of these new 80s besides Dick H?