zdz 80 prop hub
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zdz 80 prop hub
Hello everyone, Has anybody ever run succesfully a 1" prop hub extension on any of the zdz engines? I plan to use a zdz 80 in my 1/4 scale Me109 and I would like to move the engine back about an inch. Does anyone make extensions for 6 bolt hubs?
Thanks in advance
Evan Q.
http://www.homestead.com/evoshangar/me109.html
Thanks in advance
Evan Q.
http://www.homestead.com/evoshangar/me109.html
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Re: zdz 80 prop hub
Originally posted by fw190d9
Hello everyone, Has anybody ever run succesfully a 1" prop hub extension on any of the zdz engines? I plan to use a zdz 80 in my 1/4 scale Me109 and I would like to move the engine back about an inch. Does anyone make extensions for 6 bolt hubs?
Thanks in advance
Evan Q.
http://www.homestead.com/evoshangar/me109.html
Hello everyone, Has anybody ever run succesfully a 1" prop hub extension on any of the zdz engines? I plan to use a zdz 80 in my 1/4 scale Me109 and I would like to move the engine back about an inch. Does anyone make extensions for 6 bolt hubs?
Thanks in advance
Evan Q.
http://www.homestead.com/evoshangar/me109.html
I don't think this would be a big problem.
E-mail me privately and tell me more of the particulars, I'm sure I can make this for you with a good guarantee, you like you pay, you don't like you don't pay...
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prop hub
Rog, You are a true gentleman. I changed the plan somewhat in that I decided to use a 3w75its. The 3w has 3 bearings on the crank and I figured it would be better able to handle the stress of the extension. True turn is going to machine a single bolt prop hub conversion for my 3w that has a flange that is 1 inch thick. This gives me the 1 inch extension I needed and does away with the 6 prop retention bolts in favor of 1 10mm shaft. I plan to use the zdz80 in either the corsair or my vailly fw190a. I will keep your offer in mind if my current plan does not work out.
Thank you,
Evan Q.
Thank you,
Evan Q.
#4
zdz 80 prop hub
Your choice of engines really won't cure the basic condition you are setting up-using a extension.
First the ZDZ has plenty of bearing size and the placement of the third bearing means nothing , relative to your setup.
There is plenty of commenting on the "third" bearing -but actual practice shows this is pretty much a non issue
Extensions on small (1 hp)engines typically work "well enough" for most modelers.
once you get into multiple horsepower sizes - you change the ball game.
First - any imbalance - at the prop now has a greater chance of bending or breaking the extension.
The "why" is that if you are using -say 10 lbs of torque (just a example number)- to drive the prop - then there is the same amount of reaction energy out in front.
On engines which fire once each revolution (single or twin ) - this can be a sizeable whack.
Years back- extension spools for glow engines use in scale setups were common.
Personally -I would not touch one with a ten foot pole .
It matters not a whit how perfectly someone makes the parts. an extension spool- it still must run true under load. As the engine runs thru the various periods of dynamic imbalance, which ALL engines do - this puts a bending load on everything from the flywheel-back to the con rod- And this can not be cured by putting another bearing behind the con rod -
The new bearing -in a block, needs to be up front-
If you just must have an extension on the model-- use a big electric motor instead of an engine - This will smooth out the impulse problem.
.
First the ZDZ has plenty of bearing size and the placement of the third bearing means nothing , relative to your setup.
There is plenty of commenting on the "third" bearing -but actual practice shows this is pretty much a non issue
Extensions on small (1 hp)engines typically work "well enough" for most modelers.
once you get into multiple horsepower sizes - you change the ball game.
First - any imbalance - at the prop now has a greater chance of bending or breaking the extension.
The "why" is that if you are using -say 10 lbs of torque (just a example number)- to drive the prop - then there is the same amount of reaction energy out in front.
On engines which fire once each revolution (single or twin ) - this can be a sizeable whack.
Years back- extension spools for glow engines use in scale setups were common.
Personally -I would not touch one with a ten foot pole .
It matters not a whit how perfectly someone makes the parts. an extension spool- it still must run true under load. As the engine runs thru the various periods of dynamic imbalance, which ALL engines do - this puts a bending load on everything from the flywheel-back to the con rod- And this can not be cured by putting another bearing behind the con rod -
The new bearing -in a block, needs to be up front-
If you just must have an extension on the model-- use a big electric motor instead of an engine - This will smooth out the impulse problem.
.
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zdz 80 prop hub
Hey Dick...You're absoutely rignt..Except...Most engines don't have a flywheel any more, and you couldn't bend or break a 1 or 2 inch aluminum extension with a sledge hammer, much less a prop.. And...Nobody puts the third bearing BEHIND the con rod...
Picky, Picky, Picky....
Picky, Picky, Picky....
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zdz 80 prop hub
As I said Evan, I can make the piece for you, but after reading what Dick said, I beleive he might be right and one should take heed.
Dick has quite a bit of experience in this field. He probably forgot more then we will ever know about this subject.
Dick has quite a bit of experience in this field. He probably forgot more then we will ever know about this subject.
#7
zdz 80 prop hub
what is that bearing looking thingy behind and the other -in front of the "con rod" .
Or should I have said in front and behind of the crankpin?
On the chainsaw engines?
The prop is not a flywheel?
Picky -picky-
Are we both just bored?
Or should I have said in front and behind of the crankpin?
On the chainsaw engines?
The prop is not a flywheel?
Picky -picky-
Are we both just bored?
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Extension
I did have the concern that Dick has, but after using a few of these extensions made by Ralph and Tom Perry, I can tell you they WORK. Evan has raced my P51B several times w/ Q52 and a 2.5in prop hub, he even beat me once. Seriously though, the plane has around 75 flights, Tom Perry made the extension for the reason that Evan wanted his, to move the engine back for scale appearance reasons. I am sure Dick Hanson knows what he is talking about, but in practice, I have used these many times and never had a problem...Lenny
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extension
Hey Lenny, Waddya mean ONCE? Man do I gotta whup that mustang of yours again? LOL. Guys, Lenny is correct in what he says, I have seen and flown his P-51b and it flies great and there does not seem to be any excessive vibration. I think the trick is to machine the engine and spacer to work together as Tru-turn has suggested. Also, Pat McCurry who built the prototype of the kit Im building is using a similar 1 inch extension on his 3w 70. I chose the 3w75 for the 3 bearings and also because the engine construction is somewhat more "robust" than others. I have also seen several Zenoahs with 1 inch extensions and they all work great. Just ask Mr. Greg Hahn who runs one on the z445 in his dauntless that won the scale masters. Mr. Hanson, I just can see using an electric motor on a 40 lb. german warbird. I dont think it will sound right. Thanks everyone for your suggestions, I plan to use the tru turn extension which is machined from solid stainless steel and the engine hub is machined to accept the extension with no runout. I will let you all know how it works. If it doesnt , I can always space the motor forward with some of Roger's awesome standoffs.
Evan Q.
ps, Lenny, I finally leaned the zdz40 out some on the mustang, shes even faster now.
Evan Q.
ps, Lenny, I finally leaned the zdz40 out some on the mustang, shes even faster now.