Jump to content

Neuform Variable Pitch Propeller


Indiapapa

Recommended Posts

Je suis certain que votre anglais est meilleur que mon français

 

I've just uploaded the following file to the downloads area "Assembly- and Maintenance Manual V3-R2-20100428.pdf" which may have what you need.

 

It will need to be approved by an admin before it appears in the list but hopefully that won't take long - if it's urgent you could PM me your email & I'll send it direct to you.

 

Cheers

Ian

 

ps

Link to comment
Share on other sites

I want one!

 

I've got one!

 

In fact it's a mixed blessing - undoubtedly having a VP prop is good - get into the cruise, up into top gear and I see about 105 knots at 4,400 rpm - reduced fuel flow which for us Europeans with UK petrol prices is a blessing.

 

However - the mechanism is prone to losing hydraulic fluid. It's a pretty simple affair just a piston at either end and a hydraulic line between them - but no hydraulic fluid reservoir so over time it inevitably leaks a bit, loses a bit of fluid and the whole thing starts to "slacken off", the result is that you can't get to full coarse as it is set to fail-safe to full-fine. We got a mod recently with a slightly bigger flanged washer in the slave cylinder which has improved things - prior to that it would only remain fully operational for about a month before it started to lose pressure, now it seems to last 2 to 3 months before we have to put the pressure bleeder on and pump it up again.

 

If I were starting again, I think I'd go for the electrically operated CSU rather than the hydraulic option.

Link to comment
Share on other sites

A manually controllable pitch prop in a plane like the Flight Design CT is a needless complexity.  Set the prop for cruise and give up a little on takeoff....the plane is not STOL.

 

To benefit from a variable pitch propeller, for obvious reasons, an airplane certainly does not have to be "STOL."

Where does that logic come from?

 

I, as most other guys here, are in the camp of giving up as little as possible.  Your mileage may vary.

Link to comment
Share on other sites

A manually controllable pitch prop in a plane like the Flight Design CT is a needless complexity.  Set the prop for cruise and give up a little on takeoff....the plane is not STOL.

 

Okay, um...WTF?  The whole point of a variable-pitch (constant speed, whatever term you want to use) is that you get to CONTROL it.  Maximum flat for takeoff to get best climb, maximum coarse in cruise for best speed.  You give up nothing except the weight of the mechanism.  AS stated earlier, if it fails, it goes full flat so you go to a full climb prop...no safety problem.  I will take a little "needless complexity" for ~10 knots better cruise at the same fuel burn!

 

BTW, your Lancair is "not a STOL airplane" either...will it have a fixed pitch prop?    :fainting-1344:

Link to comment
Share on other sites

 I will take a little "needless complexity" for ~10 knots better cruise at the same fuel burn!

 

Most of us are pitched for best speed and use that for cruise.  I think you are in that category.

 

I already cruise at best speed so a variable pitched prop can do nothing to improve that.  If I had a vari and it worked as desired I would want to be able to do my initial climb at 5,800 rpm and still be able to WOT cruise @ 5,500 above 8,000'.  Hopefully WOT @ 5,500 at more than one altitude above 8,000.  On the coarse end I would want to see one or more cruise / economy settings for lower throttle settings.

 

I wouldn't care too much about finding 5,500 @ WOT at lower altitudes even though it wouldn't violate the continuous power limit in RPM it would exceed 75%

 

BTW constant speed is a different animal than the variable pitch (controlled in cockpit)  used on CTs.

Link to comment
Share on other sites

Okay, um...WTF?  The whole point of a variable-pitch (constant speed, whatever term you want to use) is that you get to CONTROL it.  Maximum flat for takeoff to get best climb, maximum coarse in cruise for best speed.  You give up nothing except the weight of the mechanism.  AS stated earlier, if it fails, it goes full flat so you go to a full climb prop...no safety problem.  I will take a little "needless complexity" for ~10 knots better cruise at the same fuel burn!

 

BTW, your Lancair is "not a STOL airplane" either...will it have a fixed pitch prop?    :fainting-1344:

 

The point being the little Flight Design CT is A. not an STOL (takeoff at sea level of 1200fpm is double whats needed) and B. the oil leaks and complexity to manually run the pitch will no doubt be far more trouble than anything you might gain in being able to takeoff faster, and still have optimum cruise.  Something no doubt most won't be able to achieve given it is a manual operation and open to skill and judgement.

 

We are putting a four-blade Harzell HC-H3YF-1R on the plane.  It will be automated and constant speed.

Link to comment
Share on other sites

. . . the oil leaks and complexity to manually run the pitch will no doubt be far more trouble than anything you might gain in being able to takeoff faster, and still have optimum cruise.

Who said anything about a hydraulic governor?

Think electric.

Link to comment
Share on other sites

. . . Something no doubt most won't be able to achieve given it is a manual operation and open to skill and judgement.

Are you kidding?

You have no idea about most pilots "skill and judgement."

News flash: Controlling a variable pitch propeller is not rocket science.

Link to comment
Share on other sites

Just what do you mean by "automated?"

 

 

Good question - I'd like to hear the system described.

 

I do have a lot of experience with traditional constant speed props, and the single "Power Lever" of the Cirrus was fairly elegant and well thought out. I don't think I've ever flown with a flight adjustable prop that was not constant speed.

 

Not sure what modern electronics may have added to the mix to "automate" prop pitch.

Link to comment
Share on other sites

Leaks are a faulty installation or maintenance issue.

 

I have 10 years with a hydraulic adjustment variable pitch prop (Kaspar) on a 912s CT2k with NO PROBLEMS whatsoever. Simple and effective mechanism, easily maintained and adjusted, the prop is still in perfect condition.  I had the option to put in an electric constant speed controller a couple of years ago, and did fly one in an LS.  It was certainly nice, set it and forget it, but I found no need to mess with a perfectly functional and simple system. 

 

The variable pitch controller is essential for the safest explorations of mountainous terrain, when multiple climbs and descents are the norm.  If you are a climb to altitude and cruise straight to your  destination sort of flyer, maybe not so much.

 

Apart from that, I imagine that picking one's nose is a needless complexity during flight, too.

Link to comment
Share on other sites

Interesting observation C Icey. It is the Kaspar mechanism on my LS even though the prop is a Neuform.

 

Are you saying that in 10 years you've never had to add any hydraulic fluid and the operating handle has never gone slack over the first couple of notches? I'm aware of 3 other CTLSs on the UK register that have exhibited exactly the same symptoms as mine which is why I see it as a fundamental design issue rather than a maintenance one but I'm always prepared to be educated otherwise!

Link to comment
Share on other sites

Hydraulic systems that DON'T leak are super duper rare, but they do exist (generally they are the unicorn among the build batch). There's always a tiny bit of fluid loss as time goes on. Often, a hairline scratch is all it takes.

Link to comment
Share on other sites

I've never noted any significant oil loss, but yes, I do occasionally have to make adjustments, and have noted the mushy lever. It is a regular part of my inspections. I guess the fact of adjustments means there is some flaw, but I have never considered it much more than a minor inconvenience, and never had any alarming malfunction or accumulated oil signature. It is a quick adjustment with a ratcheting 10mm hex screw at the base of the cylinder to relieve mush and to ensure a 1mm clearance of the hub at full fine.... I keep my head under the cowling often as where I fly the terrrain is rather unforgiving, so I am making minor adjustment regularly, and I have recharged the cylinder via syringe on the upper nipple, backing off the hex head, and cycling the fluid as part of inspection maintenance........  it has been ten years .... 

 

btw, C ICEY is super duper but I don't take it for granted..  variable pitch is essential for the ups and downs of exploring big mountains, maybe not so much for the climb and cruise crowd.  The pitch adjustment is quick and easy enough.  I am very satisfied with the Kaspar system, and it's operation becomes routine.

Link to comment
Share on other sites

Archived

This topic is now archived and is closed to further replies.

×
×
  • Create New...