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Don Smythe comments on Warp Angle and Movie

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dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Mon Oct 23, 2006 7:41 am Post subject: Don Smythe comments on Warp Angle and Movie

Ok Don, I just out in hangar and measured  the prop about 6 inches in from 

tip

results were    2 blades about the same and third one out 1/2 to 3/4 degree 

or so.....

At tips all three I would say within 1/4 degree.



So you say most of thrust is coming from  the 3/4 point out the length of 

the blade  which might be correct but if that is they what about the longer 

the prop, the better the climbout as a rule ?



So ,  my question is  what is the relevance ?

And what performance gain is there to be had ?

You saw the Trailerpark videos ?    http://www.cfisher.com/kitfox/ 

Takeoffs 4 to 6 seconds

What will I gain?   thoughts ?

I need comments --  are my takes offs OK ?   Am I missing something ? 

Maybe my prop is costing me performance ?

How does mine compare to others  ?  582 or 912s ?

Dave

---

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dosmythe(at)cox.net
Guest

Posted: Mon Oct 23, 2006 9:39 am Post subject: Don Smythe comments on Warp Angle and Movie

Dave,

    It was a NASA Engineer that educated me about the max thrust being 

produced somewhere in the 2/3 range.  You are the first one to ever come 

back and say that he checked the prop and found the same differences that I 

did.  Now, what is the relevance you ask???  I don't have a clue.  However, 

I think that all would agree that the three blades should be adjusted with 

exactly the same pitch to reduce vibration etc.....  If I have a problem 

adjusting at the tips and getting all blades exactly the same then I should 

look for a better way.  I found that my blades were linear all the way from 

the hubs to within 2+ inches of the tips.  Adjusting at the 2/3 point 

ensures the blades are all very close and who cares about the last 2 inches 

(tips) that do very little.

    BTW, there is no performance gain on picking a spot to adjust the props. 

Any place is fine as long as you use the exact same spot on each blade 

except the tips (IMHO)



Don Smythe

---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Mon Oct 23, 2006 3:08 pm Post subject: Don Smythe comments on Warp Angle and Movie

Hoo boy!



Just try putting a prop that is two inches longer or shorter for that

matter, on your plane before you say the last 2 inches do very little.

Don't forget the last two inches travel the fastest and travel the furthest.



On seaplanes you will find the most pitting on the tips of the blades where

spray erodes the leading edges.  On metal blades dressing the pits out to an

extent will smooth out the prop and increase thrust.  On composite

propellers filling the pits with epoxy and then dressing back to the

original surfaces will do the same thing.



Noel

who cares about the  last 2 inches (tips) that do very little.

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

lcfitt(at)sbcglobal.net
Guest

Posted: Mon Oct 23, 2006 9:30 pm Post subject: Don Smythe comments on Warp Angle and Movie

Well, Since my airplane is just outside the side door, I did the deed.  I 

just checked the prop pitch.  I usually pitch my Warp taper at the inboard 

end of the nickel leading edge - the same as everyone else I have talked to.



All checked the same there.   And the same to about three inches from the 

tip, but two inches in, big difference and one was a full bubble witdth flat 

at the tip.  Now, I am not particularly happy with my findings, but I am 

glad the bulk of the blade is pitched the same as the others.  Kudos to Don 

and his aeronautical engineer friend.



Are you suggesting that the terminal two inches is the major player in prop 

efficiency and smoothness?  And a full bubble width - 2 degrees out of pitch 

is better at the fat of the blade than the final inch or two of the tip? 

Hoo Boy!



 Won't argue the merits of blade length here.  I thought we were talking 

about blade pitch and where to put the protracter.



Lowell

---

dosmythe(at)cox.net
Guest

Posted: Tue Oct 24, 2006 3:43 am Post subject: Don Smythe comments on Warp Angle and Movie

Lowell my friend,

    Thanks but I want to know what took you are so long to check this? 

Ha....   I only reported it about 5 years ago.  It was then that I called 

Warp with your same findings.  This is where they will say, "NO WAY, 

IMPOSSIBLE".

   Rather than some get in a huff about this thread, simply do like Lowell 

did and check your prop and report the findings.  If every warp prop is the 

same way then warp would have to admit it.  Whether they do or not, at least 

the List (a select few) would benefit.



Don Smythe



---

dave

Joined: 22 Sep 2006
Posts: 1382

Posted: Tue Oct 24, 2006 4:10 am Post subject: Don Smythe comments on Warp Angle and Movie

Don,



Having found this in the first place did you try different settings?

e.g.    setting at  the 75%  the same pitch  and having different degree 

settings at tip  and was there any noticeable difference in performance 

and/or vibration ?



I will be doing some testing here next day or two I hope.   We under heavy 

snow right now but looks ok for tomorrow so far .

Also mine does seem to work ok now  an maybe in fact it not even adjust 

optimally.



Dave



---

lcfitt(at)sbcglobal.net
Guest

Posted: Tue Oct 24, 2006 5:59 am Post subject: Don Smythe comments on Warp Angle and Movie

Don,



Sorry for the five year delay.  My excuse was that I already pitched from 

well within the tip - dumb me.  I just checked  the prop manual and sure 

enough I have been doing it all wrong all these years.



My guess in all this is that the nickel leading edge has some memory and 

when it is bonded to the prop blade, the only place it can unwind and have 

any influence is at the thin tip.



Maybe this is another catagory we could add to the database - those that are 

flying with 90 percent of one blade 2 degrees out of pitch. 



Lowell

---

dosmythe(at)cox.net
Guest

Posted: Tue Oct 24, 2006 6:12 am Post subject: Don Smythe comments on Warp Angle and Movie

I think I stated this earlier but, I placed a steel machinist rule against 

the hub and marked off every two inches toward the tips (all three blades). 

I then set the pitch of all three blades at the 20" mark to 26 degrees  (I'm 

using memory on those numbers).  Once done with that, I went back and 

checked the pitch of each blade on each of the 2" marks and recorded.  Every 

recorded pitch angle was very close until I got to the last 3" and then saw 

angle differences up to 1 or more degrees.

    Again,  I did not notice any vibration difference.  Performance will be 

determined as to what angle you pitch not where you pitch at.  As a second 

thought, I never used the tips as an adjustment point and flew the plane so 

I don't know if it might affect vibration or not..



Don Smythe

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 24, 2006 7:51 am Post subject: Don Smythe comments on Warp Angle and Movie

Lowell:  



Regardless of where I think the measurements should be taken, I would take

the measurements where the manufacturer says to ( my AME training again).

If GSC says to measure their blades at .61 the length then on the GSC that's

where I take the measurements.  If the Warp people say to measure their

blades at the tip then I have to assume they have their reason for measuring

that way and that's where I would measure the Warp blade.  I do however find

it interesting that they measure their pitch at that location.



The last post I made on the length of the blade was in response to someone

who thought the tips of the blade did very little...  Of course if that were

true they would shorten the blade wouldn't they.



Noel

Do not archive

[quote] --

_________________
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Kitfox III-A
Aerocet 1100 Floats

Guy Buchanan

Joined: 16 Jul 2006
Posts: 1204
Location: Ramona, CA

Posted: Tue Oct 24, 2006 8:26 am Post subject: Don Smythe comments on Warp Angle and Movie

At 06:59 AM 10/24/2006, you wrote:

 	  Quote: 	
		  My guess in all this is that the nickel leading edge has some memory and

when it is bonded to the prop blade, the only place it can unwind and have

any influence is at the thin tip.


	


I'm got about 1/2 bubble width out, with no nickel leading edge. I suspect 

it's the usual problem with thick composite laminates. When you transition 

from thick to thin it's easy to have problems maintaining symmetry in the 

laminate. Builders typically use very thick plies to make the laminating 

faster and a little asymmetry in the bias ply trimming, or a little angle 

to the uni's and you get warps.

Guy Buchanan

K-IV 1200 / 582-C / Warp / 100% done, thanks mostly to Bob Ducar.



Do not archive

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Guy Buchanan
Deceased K-IV 1200
A glider pilot too.

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 24, 2006 8:27 am Post subject: Don Smythe comments on Warp Angle and Movie

Jus curious ...  Do all the blades have a consistent difference of pitch at

the tips or does the difference vary with the blade??



Noel



[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

dosmythe(at)cox.net
Guest

Posted: Tue Oct 24, 2006 9:45 am Post subject: Don Smythe comments on Warp Angle and Movie

I'm not sure I quite understand the question but, when I checked mine I 

simply took all the readings and compared the difference.  For instance, if 

I measured at 22" and got 24 degrees 24-1/4 degrees and 23-3/4 that's a 

total max difference of  1/2 degree.  At the tips I might have seen 12 

degrees 12-3/4 degrees and 14 degrees.  That's a max error of 2 degrees.  I 

did not make any determination that any one blade was causing the error. 

Besides, all three blades tracked very close out to the tips.

---

lcfitt(at)sbcglobal.net
Guest

Posted: Tue Oct 24, 2006 12:27 pm Post subject: Don Smythe comments on Warp Angle and Movie

Noel,



I don't agree with your conclusions on the tip length comment.  The issue is 

how much of the blade you want to be in pitch.  My measurements last evening 

agreed almost exactly with Don's measurements, except to the extent of the 

twist difference in the last inch of the one blade, mine exceeded one 

degree - I got 2 degrees.  In fact and I have to say this, when you are 

measuring prop pitch and the bubble settles completely out side of the 

lines, you just know the protractor slipped.  I repeated the blades numerous 

times and no slip.



Don reported his findings to Warp and they stated, "Impossible".  We get 

this sometimes on the list as well, people doing careful measurements and 

tests and the unbelievers arguing against the results.  One example comes to 

mind - a guy, very careful and methodical, in my opinion and worth listening 

to and still a frequent contributor to the list, reported on the results of 

tests done on his airplane with vortex generators.  His conclusions as far 

as his results went: gentler stall characteristics but little if any 

significant reduction in stall speed.  Lots of arguments as to why his 

results were wrong and suggestions on how he could improve the data to agree 

with preconceived notions about vortex gererators, i.e., every one knows 

vortex venerators reduce stall speed.



This exact thing happened on the Lancair list when one man with sets of both 

plain wingtips and the winglet wing tips.  He flew some tests and  reported 

reduced cruise speed with the winglets.  Nearly all to a man agreed that his 

tests were somehow flawed, despite the fact that this was the only hard 

evidence using the same airplane, same pilot in similar conditions with both 

types of tips.  They look cool and are expensive and hard to install, so 

they must be good for performance, besides the commercial jets use them, 

isn't that enough reason to put them on my Lancair.  Go for it I say.



I see the same thing emerging on this thread, i.e. Warp claims their blades 

are symmetrical from hub to tip - pitch at the tip.  A guy does careful 

measurements and finds Warp is wrong at least with regard to his blades and 

decided to pitch at 75%. for that reason.  Warp? Impossible.  I measure mine 

and my measurements agree with Don.  His suggestion is that we all measure 

our blades and if a significant number are "warped", notify Warp and maybe 

they will acknowledge a problem and change their "book", as in by the. 

Instead we get lots of talk about measuring by the book etc. and good enough 

for me.  (Please read Guy Buchannans related post - He is in the busines).



The 2" at the tip only came in with regard to whether you preferred the four 

square inches at the tip being in pitch or the 90 or so square inches in the 

rest of the blade being in pitch.  I think his comment to be right on - it 

is best do disregard the 4 square inches and pitch for the bulk of the blade 

as the 4 in. sq to be minimal in effect by comparison.  No one suggested 

cutting off the offending prop tips.

Lowell

---

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 24, 2006 3:34 pm Post subject: Don Smythe comments on Warp Angle and Movie

Thanks ... That is what I was wondering.  I don't mind saying I find it

strange that Warp requires you to set your blades by the tips when that

evidently is where the largest discrepancy appears to be.



Noel

Do not archive

[quote] --

_________________
Noel Loveys
Kitfox III-A
Aerocet 1100 Floats

Float Flyr

Joined: 19 Jul 2006
Posts: 2704
Location: Campbellton, Newfoundland

Posted: Tue Oct 24, 2006 5:17 pm Post subject: Don Smythe comments on Warp Angle and Movie

Lowell:



Don't get me wrong....  I'm not suggesting any one go out and hack a couple

of inches off their props.



I'm getting the feeling that in specifying the pitch angle be set by the

tips, Warp may be wrong and in fact the optimum place probably is close to

the .75 station.  In my first post on this topic I did say my training was

to set pitch at .66 station  that's a difference of about 3 inches on a 68"

prop.  



Someone said the last two inches don't make any difference to the prop.....

It is only my contention that they sure do make a difference.  If you guys

are getting large differences in pitch angle only at the tips it says to me

there is something not quite right with the blades.  If so, that's an issue

I'd take up with Warp.  Sounds like there is a problem there whether Warp

likes it or not.



As for how much of the blade is in pitch I agree with you that should be the

issue. The more of the blade in equal pitch the smother the blade should be,

assuming the tracking is consistent, which you have said it is.



On the question of vortex generators, winglets etc.  Thee are so many

variables there that the only way to see what works for you is to try it.

Lets face it nothing is perfect and sticking a few VGs on a good wing is not

likely to make a huge difference.  Putting the same VGs on a poorer wing

could have more effect. 



As you said the big jets use winglets supposedly not because they fly faster

but they are supposed to save fuel on the long haul at altitude.  I think

Boeing actually recommends not to have the winglets for regional airlines

flying the 737 - 700 as they seldom get to an extended cruise altitude

definitely outside the Lancair envelope.   Yes the winglets look cool and if

you have the ca$h to put them on ... Why not???  Just don't expect the huge,

or any increase in speed.  If you went the full gambit and added VGs, wing

fences, slats, slots, droops and winglets to the Kitfox you may never get it

off the ground.



Noel

I keep trying to remember....  Oh yes ... Do not archive.

[quote] --

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Kitfox III-A
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