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smokey_bear_40220(at)yaho
Guest

Posted: Tue Jun 27, 2006 7:27 am Post subject: Warp drive hub.

Michel,

I thought you were the smart one....  Now what???

Well, theoritically the longer prop should be better

unless the tip speed gets too high.  But then you have

the engine torque curve to consider too, not just the

prop.  The best engine/prop efficiency combined is the

actual answer and testing often proves theory a bit

off.  I'd go with test results over theory every time.

We need to borrow a large wind tunnel for a 100 hrs or

so to really out fox the Fox.  Some blowing smoke

would clear things up.  ????

I think low aspect ratio props are better, except at

low speed, as test results prove.  ie, the thicker

cord prop good at lower speeds and thinner prop at

higher speeds, but again ya' gotta test them all.

I sure would like to do some prop testing on my own,

but that would cost a lot, unless I had a source for

each candidate and could return them.  I don't think I

have the right prop, or maybe gear ratio for mine. 

Too much loss.

Kurt S.

--- Michel Verheughe <michel(at)online.no> wrote:

 	  Quote: 	
		   > From: Clem Nichols [cnichols(at)scrtc.com]

 > Kirk and Michel, you're our physicists and

 theoreticians.  Any thoughts on explaining

 > Randy's observation?

 ... what? What have you been smoking, Clem, I want

 some!  My only knowledge about propellers is

 nearly 30 years old and only with yachts. I haven't

 a clue why shortening a 72" prop to 70 would make

 both climb-out and cruise performance better.

 But thanks for the compliment, you really made my

 day! 

 PS: My Jabiru prop is only 60" diameter, which at

 WOT (3,050 prop RPM) gives me a tip moving at 285

 m/s, well under the speed of the sound of 340 m/s

 Cheers,

 Michel

 do not archive

__________________________________________________

Clem Nichols

Joined: 10 Jan 2006
Posts: 88
Location: Munfordville, Ky

Posted: Tue Jun 27, 2006 10:28 am Post subject: Warp drive hub.

Kurt, Cliff, and others:



Thanks for your response.



Clem Nichols



---

lcfitt(at)sbcglobal.net
Guest

Posted: Tue Jun 27, 2006 11:18 am Post subject: Warp drive hub.

I think you are right about cord vs. speed.  There were a number of 

ultralights and powered parachutes at the West Desert Fly-in, all powered by 

Rotax 4 strole engines and the cord of the props on them was definitely 

broader.



Also the two guys that went to the PowerFin prop here shortened theirs by 

one inch and both got better performance on both climb and cruise, but with 

the PowerFin, climb was clearly the winner.  Sorry to report that both have 

since gone to other props most recently with similar climb and better 

cruise.  One to the IVO and the other to the taper tip Warp.



Lowell

---

janderson412(at)hotmail.c
Guest

Posted: Tue Jun 27, 2006 1:09 pm Post subject: Warp drive hub.

When I ordered my prop from Warp, I gave them my power combination and they were most adamant with their recommendation. 72" taper tip and from my experience, they were spot on. Good climb and cruise, I'm more than happy.

 [quote]   

From:  kurt schrader <smokey_bear_40220(at)yahoo.com>

Reply-To:  kitfox-list(at)matronics.com

To:  kitfox-list(at)matronics.com

Subject:  RE: Warp drive hub.

Date:  Tue, 27 Jun 2006 08:26:20 -0700 (PDT)

--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220(at)yahoo.com>

Michel,

I thought you were the smart one....  Now what???

Well, theoritically the longer prop should be better

unless the tip speed gets too high.  But then you have

the engine torque curve to consider too, not just the

prop.  The best engine/prop efficiency combined is the

actual answer and testing often proves theory a bit

off.  I'd go with test results over theory every time.

We need to borrow a  large wind tunnel for a 100 hrs or

so to really out fox the Fox.  Some blowing smoke

would clear things up.  ????

I think low aspect ratio props are better, except at

low speed, as test results prove.  ie, the thicker

cord prop good at lower speeds and thinner prop at

higher speeds, but again ya' gotta test them all.

I sure would like to do some prop testing on my own,

but that would cost a lot, unless I had a source for

each candidate and could return them.  I don't think I

have the right prop, or maybe gear ratio for mine.

Too much loss.

Kurt S.

--- Michel Verheughe <michel(at)online.no> wrote:

[quote] > From: Clem Nichols [cnichols(at)scrtc.com]

 > Kirk and Michel, you're our physicists and

 theoreticians.  Any thoughts on explaining

 > Randy's

smokey_bear_40220(at)yaho
Guest

Posted: Tue Jun 27, 2006 5:03 pm Post subject: Warp drive hub.

Those are the blades I have John.



Trying to get my mind on topic again to think this in

debth.  Not always easy these days.



Wider blades grip air, like all WX tires grip the

pavement.  Narrow blades more like dragster tires. 

You get a better bite with the wider blades from the

start = more static thrust and less slippage.  But the

narrow blades come into their own as you speed up and

allow the engine to spool up better from the start. 

The wider ones should run more draggy at higher speeds

and, as was said, for descent and landing.



If your tires grip and not slip, you need a lower

gear.  If your prop grips from the start, you use less

pitch to keep RPM's up.  Less pitch means the wide

cord blades will run out of pitch sooner in cruise. 

Fixed pitch would theoritically like the narrow

blades.  But if you have a cockpit adjustable prop,

the wider blades might be better?



Less diameter should mean some more slip too.  Less

efficiency on the same pitch and rpm, but maybe allows

more HP from the motor.....  You'd need to add a

little pitch for the reduced diameter, so it should be

less static thrust and maybe a slight plus in cruise.



I just can´t see enough gain from reduced diameter to

equate to that big a gain in performance from diameter

alone.  Unless there is more to the story, I'd think

the blade cord change was the bigger factor.



Again I have to yield to testing.



I need to static thrust test my plane some day too. 

Lance claimed over 700 lbs of thrust?  Don't think I

am getting that....



Kurt S.



--- John Anderson <janderson412(at)hotmail.com> wrote:



When I ordered my prop from Warp, I gave them my power

combination and they were most adamant with their

recommendation. 72" taper tip and from my experience,

they were spot on. Good climb and cruise, I'm more

than happy.



__________________________________________________

rjdaugh(at)rapidnet.com
Guest

Posted: Tue Jun 27, 2006 8:19 pm Post subject: Warp drive hub.

Aw, come on.  You guys are making this too complicated.



Like Kurt says wide blades grip the air.  The Powerfin is a wide blade.  It

definitely grips the air!  It doesn't slip much - especially in the longer

blade version.  So if you put in lots of pitch for fast cruise speed, you

can't get any RPM on the ground.  No RPM == no horse power.  (Horse power =

torque X RPM)  So more accurately: low RPM = low horsepower = long take off

roll and low climb rate.



Or low pitch means you can get RPM's up on the take off and climb, but

limited top speed.



So you cut the blades shorter, the prop doesn’t grip the air as good - so

with more pitch you get faster cruise and with more slippage on take off and

climb, you get more RPM (= more horsepower!) and so shorter take off and

climb.



I am glad that Lowell confirmed that at least two others have had the same

result with the shorter prop.  I guess you lose more disc area with the

shorter prop than the 1" shorter blade would indicate.



Randy - also looking for a different prop......  Think I am going to try a

Kiev.  



.           

--

Graeme Toft

Joined: 09 Jan 2006
Posts: 123

Posted: Tue Jun 27, 2006 9:53 pm Post subject: Warp drive hub.

One of my mates has a light wing with a Kiev and gets 5 knots better 

performance than the other lightwings in the area that are using other prop 

types. Climb is also much better but beware of the Kievs construction. They 

are dead light in comparison to a Warp as testified by the results of him 

flying into one of his cows that wandered into his take off run. The prop 

literally disintegrated where as my Warp would have survived a 50 knot 

impact had the plane not rolled onto her back in the water.

Regards

Graeme



Ph: 07 49397011

Mob: 0411476527

---

Michel

Joined: 10 Jan 2006
Posts: 966
Location: Norway

Posted: Wed Jun 28, 2006 2:37 am Post subject: Warp drive hub.

From:  kurt schrader  smokey_bear_40220(at)yahoo.com  

 	  Quote: 	
		   Michel,

 I thought you were the smart one....  Now what???


	


Well Kurt, when Mathilde, my 10 1/2 months old grand-daughter, listens while staring at me with her big round eyes, wondering how much wisdom can come out of my lips - she usually concludes by saying: "Geeee, yeeeahhh, gaga! ... ga?"

.. it says it all, doesn't it? 



Cheers,

Michel



do not archive

_________________
Kitfox 3 - Jabiru 2200

smokey_bear_40220(at)yaho
Guest

Posted: Wed Jun 28, 2006 2:46 pm Post subject: Warp drive hub.

Definately words of wisdom.... from her.  



Kurt s.



--- Michel Verheughe <michel(at)online.no> wrote:



 	  Quote: 	
		    From:  kurt schrader  smokey_bear_40220(at)yahoo.com  

 > Michel,

 > I thought you were the smart one....  Now what???

 

 Well Kurt, when Mathilde, my 10 1/2 months old

 grand-daughter, listens while staring at me with her

 big round eyes, wondering how much wisdom can come

 out of my lips - she usually concludes by saying:

 "Geeee, yeeeahhh, gaga! ... ga?"

 ... it says it all, doesn't it? 

 

 Cheers,

 Michel

 

 do not archive


	


__________________________________________________

janderson412(at)hotmail.c
Guest

Posted: Wed Jun 28, 2006 8:35 pm Post subject: Warp drive hub.

Yes, that makes good sense to me Kurt..well explained. I do find that it takes quite a punch of power to get the wheels rolling to taxi and on t/o the acceleration is gentle for a start but really begins to bite once she's up and away so that ties in. I'll take more notice tomorrow when I fly again. Took my boy yest (test engineer), first passenger and sure made a differance. John

 

 [quote]   

From:  kurt schrader <smokey_bear_40220(at)yahoo.com>

Reply-To:  kitfox-list(at)matronics.com

To:  kitfox-list(at)matronics.com

Subject:  RE: Warp drive hub.

Date:  Tue, 27 Jun 2006 18:02:47 -0700 (PDT)

--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220(at)yahoo.com>



Those are the blades I have John.



Trying to get my mind on topic again to think this in

debth.  Not always easy these days.



Wider blades grip air, like all WX tires grip the

pavement.  Narrow blades more like dragster tires.

You get a better bite with the wider blades from the

start = more static thrust and less slippage.  But the

narrow blades come into their own as you speed up and

allow the engine to spool up  better from the start.

The wider ones should run more draggy at higher speeds

and, as was said, for descent and landing.



If your tires grip and not slip, you need a lower

gear.  If your prop grips from the start, you use less

pitch to keep RPM's up.  Less pitch means the wide

cord blades will run out of pitch sooner in cruise.

Fixed pitch would theoritically like the narrow

blades.  But if you have a cockpit adjustable prop,

the wider blades might be better?



Less diameter should mean some more slip too.  Less

efficiency on the same pitch and rpm, but maybe allows

more HP from the motor.....  You'd need to add a

little pitch for the reduced diameter, so it should be

less static thrust and maybe a slight plus in cruise.



I just can´t see enough gain from reduced diameter to

equate

janderson412(at)hotmail.c
Guest

Posted: Wed Jun 28, 2006 8:37 pm Post subject: Warp drive hub.

Yes, that makes good sense to me Kurt..well explained. I do find that it takes quite a punch of power to get the wheels rolling to taxi and on t/o the acceleration is gentle for a start but really begins to bite once she's up and away so that ties in. I'll take more notice tomorrow when I fly again. Took my boy yest (test engineer), first passenger and sure made a differance. John 

Forgot to mention the deacceleration, very little when you close the throttle thus requiring a bit of f/ward planning on approach and boy do I hate it when the tower askes for a tight approach. I've had to resort to side slipping a couple of times, seems to work ok? Any comments on this?

 

 [quote]   

From:  kurt schrader <smokey_bear_40220(at)yahoo.com>

Reply-To:  kitfox-list(at)matronics.com

To:  kitfox-list(at)matronics.com

Subject:  RE: Warp drive hub.

Date:  Tue, 27 Jun 2006 18:02:47 -0700 (PDT)

--> Kitfox-List message posted by: kurt schrader <smokey_bear_40220(at)yahoo.com>



Those are the blades I have John.



Trying to get my mind on topic again to think this in

debth.  Not always easy these days.



Wider blades grip air, like all WX tires grip the

pavement.  Narrow blades more like dragster tires.

You get a better bite with the wider blades from the

start = more static thrust and less slippage.  But the

narrow blades come into their own as you speed up and

allow the engine to spool up  better from the start.

The wider ones should run more draggy at higher speeds

and, as was said, for descent and landing.



If your tires grip and not slip, you need a lower

gear.  If your prop grips from the start, you use less

pitch to keep RPM's up.  Less pitch means the wide

cord blades will run out of pitch sooner in cruise.

Fixed pitch would theoritically like the narrow

blades.  But if you have a cockpit adjustable prop,

the wider blades might be better?



Less diameter should mean some more slip too.  Less

efficiency on the same pitch and rpm, but maybe allows

more HP from the motor.....  You'd need to add a

little pitch for the reduced diameter, so it should be

less static thrust and maybe a slight plus in cruise.



I just can´t see enough gain from reduced diameter to

equate

janderson412(at)hotmail.c
Guest

Posted: Wed Jun 28, 2006 8:44 pm Post subject: Warp drive hub.

Surely one would only go for a shorter prop if g/clearance or high RPM is a factor. Smaller prop, less thrust area but more pitch and more induced drag to get the same thrust? John A.

 

 [quote]   

From:  "Randy Daughenbaugh" <rjdaugh(at)rapidnet.com>

Reply-To:  kitfox-list(at)matronics.com

To:  <kitfox-list(at)matronics.com>

Subject:  RE: Warp drive hub.

Date:  Tue, 27 Jun 2006 22:15:38 -0600

--> Kitfox-List message posted by: "Randy  Daughenbaugh" <rjdaugh(at)rapidnet.com>



Aw, come on.  You guys are making this too complicated.



Like Kurt says wide blades grip the air.  The Powerfin is a wide blade.  It

definitely grips the air!  It doesn't slip much - especially in the longer

blade version.  So if you put in lots of pitch for fast cruise speed, you

can't get any RPM on the ground.  No RPM == no horse power.  (Horse power =

torque X  RPM)  So more accurately: low RPM = low horsepower = long take off

roll and low climb rate.



Or low pitch means you can get RPM's up on the take off and climb, but

limited top speed.



So you cut the blades shorter, the prop doesn’t grip the air as good - so

with more pitch you get faster cruise and with more slippage on take off and

climb, you get more RPM (= more horsepower!) and so shorter take off and

climb.



I am glad that Lowell confirmed that at least two others have had the same

result with the shorter prop.  I guess you lose more disc area with the

shorter prop than the 1" shorter blade would indicate.



Randy - also looking for a different prop......  Think I am going to try a

Kiev.



.

--

smokey_bear_40220(at)yaho
Guest

Posted: Thu Jun 29, 2006 9:23 am Post subject: Warp drive hub.

Somewhat the same with me John.  On grass it takes a

bit to move.  If I use my normal takeoff power, I

probably use 500 feet or 8 seconds to lift off of

grass.  (Timed from movie camera footage of my

takeoffs from the cockpit.)



If I use full power, which I can get with the cockpit

adjustable prop, that last 300 RPM really peaks the

turbo and you can feel the change.  About equal to

going from 2 people to solo.  It is on the top end of

speed where I seem to run out with this prop.  More HP

isn´t going to more speed.



On landing I am still trying to find a reliable way to

set pitch for less float and yet have go-around power

available.  I can either float, or make a bunch of

noise as I land when I wanted to go.  So far, I try to

set 2000 rpm at closed throttle and accept that, but I

do float.  Slips are very useful.



Kurt S.



--- John Anderson <janderson412(at)hotmail.com> wrote:



Yes, that makes good sense to me Kurt..well explained.

I do find that it takes quite a punch of power to get

the wheels rolling to taxi and on t/o the acceleration

is gentle for a start but really begins to bite once

she's up and away so that ties in. I'll take more

notice tomorrow when I fly again. Took my boy yest

(test engineer), first passenger and sure made a

differance. John



Forgot to mention the deacceleration, very little when

you close the throttle thus requiring a bit of f/ward

planning on approach and boy do I hate it when the

tower askes for a tight approach. I've had to resort

to side slipping a couple of times, seems to work ok?

Any comments on this?



__________________________________________________

janderson412(at)hotmail.c
Guest

Posted: Thu Jun 29, 2006 12:46 pm Post subject: Warp drive hub.

Kurt, With an inflight adustable, do you not set full fine (or t/off 

setting) on final for go around?

On t/o with the prop setting I have now, the diff between 4300 and 4700 is 

like day and night but as you say, it's the turbo boost at the latter 

setting that make the diff. I still need to coursen up a bit as full noise 

is still over 5000. If only I could get time to play...John

Reply-To: kitfox-list(at)matronics.com




<smokey_bear_40220(at)yahoo.com>



Somewhat the same with me John.  On grass it takes a

bit to move.  If I use my normal takeoff power, I

probably use 500 feet or 8 seconds to lift off of

grass.  (Timed from movie camera footage of my

takeoffs from the cockpit.)



If I use full power, which I can get with the cockpit

adjustable prop, that last 300 RPM really peaks the

turbo and you can feel the change.  About equal to

going from 2 people to solo.  It is on the top end of

speed where I seem to run out with this prop.  More HP

isn´t going to more speed.



On landing I am still trying to find a reliable way to

set pitch for less float and yet have go-around power

available.  I can either float, or make a bunch of

noise as I land when I wanted to go.  So far, I try to

set 2000 rpm at closed throttle and accept that, but I

do float.  Slips are very useful.



Kurt S.



--- John Anderson <janderson412(at)hotmail.com> wrote:



Yes, that makes good sense to me Kurt..well explained.

I do find that it takes quite a punch of power to get

the wheels rolling to taxi and on t/o the acceleration

is gentle for a start but really begins to bite once

she's up and away so that ties in. I'll take more

notice tomorrow when I fly again. Took my boy yest

(test engineer), first passenger and sure made a

differance. John



Forgot to mention the deacceleration, very little when

you close the throttle thus requiring a bit of f/ward

planning on approach and boy do I hate it when the

tower askes for a tight approach. I've had to resort

to side slipping a couple of times, seems to work ok?

Any comments on this?



__________________________________________________





_________________________________________________________________

Discover fun and games at  (at)  http://xtramsn.co.nz/kids

smokey_bear_40220(at)yaho
Guest

Posted: Fri Jun 30, 2006 12:21 pm Post subject: Warp drive hub.

John,



Roger the "play time".



Without a prop pitch gauge, I have no defined

reference to set to in flight other than Max pitch or

Min in flight pitch.  The minimum pitch in flight

gives me some static thrust before max RPM is reached,

but seems way too low for go-around in flight.



The takeoff setting is too much thrust, or too little

idle rpm.  Either a great floater, or a dead stick

landing.



What I am setting is just a slight amount of positive

thrust with nearly closed throttle.



In any case, so far I need to power up on go-around

and keep advancing the pitch with power in coordinated

steps.  Not exactly an obstical clearing proceedure

until I master it.



Remember, the CAP prop is reversable.  There is no

"full fine" but a minimum pitch above about 2000 rpm. 

Below that rpm you can go into reverse.  Makes for a

steep pattern and short landing!



Kurt S.



--- John Anderson <janderson412(at)hotmail.com> wrote:



 	  Quote: 	
		   Kurt, With an inflight adustable, do you not set

 full fine (or t/off setting) on final for go around?

 On t/o with the prop setting I have now, the diff

 between 4300 and 4700 is 

 like day and night but as you say, it's the turbo

 boost at the latter 

 setting that make the diff. I still need to coursen

 up a bit as full noise 

 is still over 5000. If only I could get time to

 play...John


	


__________________________________________________

morid(at)northland.lib.mi
Guest

Posted: Fri Jun 30, 2006 1:18 pm Post subject: Warp drive hub.

Kurt, that CAP can go into reverse, but not in flight.  It has sprung

counterweights built into it and won't go into beta so long as the prop is

spinning above a certain rpm.  Even though your engine rpm may read 1400 or

so, the prop rpm is usually much higher on final because of the free

wheeling.  Not sure what rpm the weights are set for, but it's well below

what the rpm would be on final.  I can't get mine to go beta until it's

going pretty slow on the ground.  This may vary somewhat depending on the

weights.  That would be pretty scary to have that go into beta on final.

Deke

 	  Quote: 	

 Remember, the CAP prop is reversable.  There is no

 "full fine" but a minimum pitch above about 2000 rpm.

 Below that rpm you can go into reverse.  Makes for a

 steep pattern and short landing!

 Kurt S.

 --- John Anderson <janderson412(at)hotmail.com> wrote:

 > Kurt, With an inflight adustable, do you not set

 > full fine (or t/off setting) on final for go around?

 > On t/o with the prop setting I have now, the diff

 > between 4300 and 4700 is

 > like day and night but as you say, it's the turbo

 > boost at the latter

 > setting that make the diff. I still need to coursen

 > up a bit as full noise

 > is still over 5000. If only I could get time to

 > play...John

 __________________________________________________

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