---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Tue 05/09/06: 26 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 12:51 AM - Re: Thrust - Over Rated (Michael Gibbs) 2. 01:52 AM - SV: Tundra tyres. (Michel Verheughe) 3. 03:50 AM - Re: [Off-topic] English (Michel Verheughe) 4. 03:59 AM - Re: Thrust - Over Rated (Michel Verheughe) 5. 06:23 AM - Re: Tundra tyres. (skyflyte@comcast.net) 6. 06:26 AM - Painting Templates (Colin Durey) 7. 06:36 AM - Re: Thrust - Over Rated? (Lowell Fitt) 8. 07:08 AM - Re: Re: Thrust - Over Rated (Lowell Fitt) 9. 07:29 AM - Re: Re: Thrust - Over Rated (wingsdown) 10. 07:29 AM - Re: Re: Thrust - Over Rated (alnanarthur) 11. 08:27 AM - Re: Re: Thrust - Over Rated (Algate) 12. 08:39 AM - Re: Re: Thrust - Over Rated (ron schick) 13. 08:48 AM - Re: Tundra tyres. (Rex) 14. 09:26 AM - Re: Thrust - Over Rated? (Randy Daughenbaugh) 15. 12:51 PM - (kenneth schooley) 16. 12:51 PM - Re: Thrust - Over Rated? (ron schick) 17. 03:25 PM - Re: Re: Thrust - Over Rated (John Anderson) 18. 03:25 PM - Re: SV: Tundra tyres. (kurt schrader) 19. 05:38 PM - Re: Re: Thrust - Over Rated (kurt schrader) 20. 05:50 PM - Re: Re: Thrust - Over Rated (kurt schrader) 21. 06:55 PM - 912S/ oil cooler efficiency (Fred Shiple) 22. 06:55 PM - Thrust...Overrated? (Clem Nichols) 23. 07:26 PM - Re: 912S/ oil cooler efficiency (John King) 24. 08:22 PM - Re: Re: Thrust - Over Rated (John Anderson) 25. 08:23 PM - Re: 912S/ oil cooler efficiency (Fred Shiple) 26. 08:30 PM - Re: Elevator hinge tab question?? (darinh) ________________________________ Message 1 _____________________________________ Time: 12:51:47 AM PST US From: Michael Gibbs Subject: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: Michael Gibbs Randy sez: >In short, if you want more thrust, all you have to do is sacrifice >top speed. Therefore, thrust is irrelevant. If you want more thrust AND more top speed, you get an in-flight adjustable prop. You wouldn't drive your car in one gear all the time, why operate your airplane that way? Mike G. N728KF ________________________________ Message 2 _____________________________________ Time: 01:52:02 AM PST US From: Michel Verheughe Subject: SV: Kitfox-List: Tundra tyres. --> Kitfox-List message posted by: Michel Verheughe From: kurt schrader [smokey_bear_40220@yahoo.com] > Have you seen any crop circles lately? ;-) Yes, concentric circles about the size of the distance between the main gears of a B-767 and your name was all over it! The Norwegian authorities are being informed! :-) > I had a tire on my van where the tread looked fine, but seperated internally and > got a big flat spot. That could have happened to me too. I'll need to look at it. But, Ron and Kurt, here a good analogy: If you press hard with your thumb on the fabric of your wing, you'll make a hollow that will come back to normal after a time and/or with the help of heat. Well, my tyres are exactly the same, except that they don't seem to come back to the normal smooth and round shape. Since there is nothing visible on the outside, maybe there is something damaged on the inside. But I can't imagine what, when I look at the inside of the old tyres. What do you think? Cheers, Michel ________________________________ Message 3 _____________________________________ Time: 03:50:46 AM PST US From: Michel Verheughe Subject: RE: Kitfox-List: [Off-topic] English --> Kitfox-List message posted by: Michel Verheughe > From: Lowell Fitt [lcfitt@sbcglobal.net] > Sorry to say this, but manover gets the underline treatment. My dictionary > insists on maneuver as the cerect spellin. Sorry, my mistake, Lowell, I tried too hard to make it American-as-it-sounds-like! :-) I'd just like to add a wee bit here: the reason I use a speller, read Time and try to write proper English is that, for many years now, I have to write brochures in English, for the international maritime marked. The funny thing is that I write English better than Norwegian, the country where I have lived for the past 30 years. It proves one thing: once you put your mind to do something well, ... it gets better with time. Oh, just another precision: In Belgium and Norway (probably other too), the English we learn at school is British English. I guess it's like when you learn Spanish in the US, you don't learn Mexican but Castilian, the language spoken by the people of Castilla in Spain. Cheers, Michel do not archive ________________________________ Message 4 _____________________________________ Time: 03:59:08 AM PST US From: Michel Verheughe Subject: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: Michel Verheughe > From: Michael Gibbs [MichaelGibbs@cox.net] > You wouldn't drive your car in one gear all the > time, why operate your airplane that way? Well ... yes, when you have a Jabiru engine that doesn't like much more than a solid wooded prop, Mike! :-) But, as I have said before, I love the idea of an in-flight adjustable prop ever since my father put a adjustable pitch prop on our sailboat when I was a child. In-flight adjustable pitch is my wet dream ... well, my second wet dream! :-) Cheers, Michel do not archive ________________________________ Message 5 _____________________________________ Time: 06:23:16 AM PST US From: skyflyte@comcast.net Subject: Re: Kitfox-List: Tundra tyres. --> Kitfox-List message posted by: skyflyte@comcast.net I have lumpy looking tires like that too! Mine are caused by the inner tube, which can fold over on itself due to the low inflation pressure. After I found out the cause, I quit worrying about it. -------------- Original message -------------- From: Michel Verheughe > --> Kitfox-List message posted by: Michel Verheughe > > On May 7, 2006, at 6:38 PM, kurt schrader wrote: > > Hummm. Some tires still show a seam where the belt wrap joins. > > This is not the case, Kurt. Please look at these photos I took today: > > http://home.online.no/~michel/tmp/Tyres.jpg > > On the two upper photos, you can see, in the red circle, the > depressions in the tyres. On the lower photo, the steel rail that may > be the cause of the depressions. It's the only thing I can think of. > Strange, isn't it? Also note that the hangar (actually an old workshop > for the airfield) is not wide enough to get my Kitfox in and out > straight. When over the rail, I have to turn the plane 180 degrees to > get one wing out at the time. > > Cheers, > Michel > > > > > > > > > > > > >
I have lumpy looking tires like that too!  Mine are caused by the inner tube, which can fold over on itself due to the low inflation pressure.  After I found out the cause, I quit worrying about it.
 
-------------- Original message --------------
From: Michel Verheughe <michel@online.no>

> --> Kitfox-List message posted by: Michel Verheughe
>
> On May 7, 2006, at 6:38 PM, kurt schrader wrote:
> > Hummm. Some tires still show a seam where the belt wrap joins.
>
> This is not the case, Kurt. Please look at these photos I took today:
>
> http://home.online.no/~michel/tmp/Tyres.jpg
>
> On the two upper photos, you can see, in the red circle, the
> depressions in the tyres. On the lower photo, the steel rail that may
> be the cause of the depressions. It's the only thing I can think of.
> Strange, isn't it? Also note that the hangar (actually an old workshop
> for the airfield) is not wide enough to get my Kitfox in and out
> straight. When over the rail, us sup ________________________________ Message 6 _____________________________________ Time: 06:26:33 AM PST US Subject: Kitfox-List: Painting Templates From: "Colin Durey" --> Kitfox-List message posted by: "Colin Durey" Hi folks, I'm starting to plan the colour scheme for my (our) KF IV - I'm in a syndicate of 3. We are trying to get the decision process rolling for choosing colours and layout, as it will only be a few weeks before we put the fabric on, and will then need to be ready to paint. Some time back, either on this list, or one of the Kitfox sites, I saw reference to painting templates for the KF IV. They appeared to be side view line drawings. Does anyone know of these, and where they can be found? Regards Colin Durey Sydney +61-418-677073 (M) +61-2-945466162 (F) ________________________________ Message 7 _____________________________________ Time: 06:36:43 AM PST US From: "Lowell Fitt" Subject: Re: Kitfox-List: Thrust - Over Rated? --> Kitfox-List message posted by: "Lowell Fitt" Error Message, Regarding the Powerfin, one went to the Ivo, not the Warp and I am not sure he is happy with it. Lowell ----- Original Message ----- From: "Lowell Fitt" Sent: Monday, May 08, 2006 7:58 PM Subject: Re: Kitfox-List: Thrust - Over Rated? > --> Kitfox-List message posted by: "Lowell Fitt" > > Randy, > > No flames here. I have two friends that went to the PowerFin. They had > the > exact issues you had and eventually went to the shortened blades. They > got > the improvements you did. One is now with the Warp and doesn't know if he > likes it. I think the other still has the Powerfin. They'll both be at > the > Cameron Park fly-in. > > I guess that is what the poor man's dyno was all about - finding the HP at > the prop. > > Lowell > ----- Original Message ----- > From: "Randy Daughenbaugh" > To: > Sent: Monday, May 08, 2006 7:08 PM > Subject: Kitfox-List: Thrust - Over Rated? > > >> --> Kitfox-List message posted by: "Randy Daughenbaugh" >> >> >> I have been seeing discussion of thrust lately and I think it is nearly >> irrelevant. >> >> I have a PowerFin three blade prop on a 912S Series 5/7. When I first >> set >> it up, static RPM was 5800 RPM. And MAN DID IT HAVE THRUST! The >> acceleration would make your head snap back as you pushed the throttle >> in. >> Well, it came time for first flight, and boy did it get off the ground >> fast! >> I don't have good numbers, but I am guessing about 150 feet ground roll. >> BUT (you had to know that was coming), it would only fly about 65 - 70 >> mph >> without over-reving the engine. >> >> So I put in more pitch on the prop. Got up to 85 mph. But lower static >> rpm, less thrust and acceleration, longer ground roll. Added more >> pitch - >> 95 mph, and less thrust. More pitch - WOT about 108 mph - cruise at >> 5500 >> rpm about 96 mph - static rpm about 4900 rpm. But now ground roll on >> take >> off approaching 500 ft. Spam can territory! >> >> PowerFin said they would shorten the prop 1" each blade. I finally took >> them up on it, but it was a tough decision for me.... When I put it back >> on >> the plane, I added a degree and a quarter more pitch. Now I cruise at >> 106 >> mph AND off the ground much quicker - maybe 275' solo. >> >> In short, if you want more thrust, all you have to do is sacrifice top >> speed. Therefore, thrust is irrelevant. >> >> Indeed, it is more complicated than that. An "efficient" prop slips >> enough >> on take off to get the rpm up so that you can use most of your horse >> power >> to get off the ground, but still has enough pitch so that you can get a >> decent top speed. My plane is "over prop'ed" with the three blade >> PowerFin. >> I am saving my nickels for the Sensinich ground adjustable two blade. >> >> I would have written this earlier but was in Montana visiting my new >> grandson and didn't have my flame suit with me. >> >> Randy - Everything in aviation is a compromise. >> >> . >> >> >> >> >> >> >> >> >> >> >> >> >> > > > ________________________________ Message 8 _____________________________________ Time: 07:08:10 AM PST US From: "Lowell Fitt" Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "Lowell Fitt" Mike, I couldn't agree with you more. However there are airframe - engine - prop combinations that will give enough of each with a fixed pitch prop that the cost / benefit and complexity just hasn't made me even think about yet. In our airplanes, I think an argument could be made that a cockpit adjustable prop is sort of like a bandade for a mismatched engine - airframe. Personally I like the simplicity in flight and the lack of prop maintenane issues of the old fashioned ground adjustable Warp Drive prop. I can almost keep up with the PowerFin in climb and cruise has never been an issue for me, I can get plenty. Lowell ----- Original Message ----- From: "Michael Gibbs" Sent: Tuesday, May 09, 2006 12:48 AM Subject: Kitfox-List: Re: Thrust - Over Rated > --> Kitfox-List message posted by: Michael Gibbs > > Randy sez: > >>In short, if you want more thrust, all you have to do is sacrifice >>top speed. Therefore, thrust is irrelevant. > > If you want more thrust AND more top speed, you get an in-flight > adjustable prop. You wouldn't drive your car in one gear all the > time, why operate your airplane that way? > > Mike G. > N728KF > > > ________________________________ Message 9 _____________________________________ Time: 07:29:05 AM PST US From: "wingsdown" Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "wingsdown" If you have to turn the engine as fast or nearly so for take off as for fast flight, then an in-flight adjustable prop has merit. Even slow turning dinosaur engines for the most part have constant speed props. Band-Aids come in all shapes and sizes. Some are built right in and you never see them or for that matter know they are there. And are quite subjective as to definition. Rick -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lowell Fitt Sent: Tuesday, May 09, 2006 7:05 AM Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "Lowell Fitt" Mike, I couldn't agree with you more. However there are airframe - engine - prop combinations that will give enough of each with a fixed pitch prop that the cost / benefit and complexity just hasn't made me even think about yet. In our airplanes, I think an argument could be made that a cockpit adjustable prop is sort of like a bandade for a mismatched engine - airframe. Personally I like the simplicity in flight and the lack of prop maintenane issues of the old fashioned ground adjustable Warp Drive prop. I can almost keep up with the PowerFin in climb and cruise has never been an issue for me, I can get plenty. Lowell ----- Original Message ----- From: "Michael Gibbs" Sent: Tuesday, May 09, 2006 12:48 AM Subject: Kitfox-List: Re: Thrust - Over Rated > --> Kitfox-List message posted by: Michael Gibbs > --> > > Randy sez: > >>In short, if you want more thrust, all you have to do is sacrifice top >>speed. Therefore, thrust is irrelevant. > > If you want more thrust AND more top speed, you get an in-flight > adjustable prop. You wouldn't drive your car in one gear all the > time, why operate your airplane that way? > > Mike G. > N728KF > > > ________________________________ Message 10 ____________________________________ Time: 07:29:05 AM PST US From: alnanarthur Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: alnanarthur Mike, You are right, everything in life is a tradeoff. A Harrier Jet takes off with zero ground roll and goes fast! A ground adjustable has less parts, is more reliable and less expensive. Also, it's allowed under the sport pilot rule. I get off the ground in about 200 ft (solo), climb at 1200 ft/min and cruise at 105 mph at 5200 rpm. Allan Arthur, Sport Pilot Kitfox 5, N40AA Rotax 912s, Warpdrive 3 blade Byron Airport, CA (C83) Hanger C8 On May 9, 2006, at 12:48 AM, Michael Gibbs wrote: > --> Kitfox-List message posted by: Michael Gibbs > > > Randy sez: > >> In short, if you want more thrust, all you have to do is sacrifice >> top speed. Therefore, thrust is irrelevant. > > If you want more thrust AND more top speed, you get an in-flight > adjustable prop. You wouldn't drive your car in one gear all the > time, why operate your airplane that way? > > Mike G. > N728KF > > ________________________________ Message 11 ____________________________________ Time: 08:27:16 AM PST US From: "Algate" Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "Algate" I don't know that IFA props could be considered bandaids. No matter how well matched your engine may be to the airframe it is always a compromise to every other set of circumstances other than the ideal situation the combination has been "tuned" for. The IFA prop allows the "tuning" for a wide range of variable conditions. I'm sure that when you have a fixed or ground adjustable prop there might be the time you would like the flexibility of a IFA prop ie. When you have landed on a small lake a long way from home (so you have max fuel) and you catch a serious number of large fish. All of a sudden the shore line looks a lot closer and the thought of an additional 300ft/min climb looks pretty inviting. Likewise there are times when it's really convenient to be able to maintain airspeed, lower fuel consumption and noise by simply flicking a switch. I think sometimes simplicity can be a state of mind that comes with being comfortable with a technology - I guess even an electric light bulb looked pretty daunting when it was first introduced. No flame intended! GaryA Lite2 -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lowell Fitt Sent: Tuesday, May 09, 2006 10:05 AM Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "Lowell Fitt" Mike, I couldn't agree with you more. However there are airframe - engine - prop combinations that will give enough of each with a fixed pitch prop that the cost / benefit and complexity just hasn't made me even think about yet. In our airplanes, I think an argument could be made that a cockpit adjustable prop is sort of like a bandade for a mismatched engine - airframe. Personally I like the simplicity in flight and the lack of prop maintenane issues of the old fashioned ground adjustable Warp Drive prop. I can almost keep up with the PowerFin in climb and cruise has never been an issue for me, I can get plenty. Lowell ----- Original Message ----- From: "Michael Gibbs" Sent: Tuesday, May 09, 2006 12:48 AM Subject: Kitfox-List: Re: Thrust - Over Rated > --> Kitfox-List message posted by: Michael Gibbs > > Randy sez: > >>In short, if you want more thrust, all you have to do is sacrifice >>top speed. Therefore, thrust is irrelevant. > > If you want more thrust AND more top speed, you get an in-flight > adjustable prop. You wouldn't drive your car in one gear all the > time, why operate your airplane that way? > > Mike G. > N728KF > > > ________________________________ Message 12 ____________________________________ Time: 08:39:45 AM PST US From: "ron schick" Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "ron schick" Hi Alan Yes thrust is a variable with pich and length of prop. The VW's have been limited to small slippery airplanes due to the fact they have to swing a small prop in order to get in the power band. My goal is to use a redrive that allows a large prop suitable for the Kitfox performance range. Ron NB Ore >From: alnanarthur >To: kitfox-list@matronics.com >Subject: Re: Kitfox-List: Re: Thrust - Over Rated >Date: Tue, 9 May 2006 07:28:14 -0700 > >--> Kitfox-List message posted by: alnanarthur > >Mike, > >You are right, everything in life is a tradeoff. > >A Harrier Jet takes off with zero ground roll and goes fast! > >A ground adjustable has less parts, is more reliable and less expensive. >Also, it's allowed under the sport pilot rule. > >I get off the ground in about 200 ft (solo), climb at 1200 ft/min and >cruise at 105 mph at 5200 rpm. > > >Allan Arthur, Sport Pilot >Kitfox 5, N40AA >Rotax 912s, Warpdrive 3 blade >Byron Airport, CA (C83) Hanger C8 > > >On May 9, 2006, at 12:48 AM, Michael Gibbs wrote: > > > --> Kitfox-List message posted by: Michael Gibbs > > > > > > Randy sez: > > > >> In short, if you want more thrust, all you have to do is sacrifice > >> top speed. Therefore, thrust is irrelevant. > > > > If you want more thrust AND more top speed, you get an in-flight > > adjustable prop. You wouldn't drive your car in one gear all the > > time, why operate your airplane that way? > > > > Mike G. > > N728KF > > > > > > > > > > > > > > > > > > > > > > > > > > _________________________________________________________________ Express yourself instantly with MSN Messenger! Download today - it's FREE! http://messenger.msn.click-url.com/go/onm00200471ave/direct/01/ ________________________________ Message 13 ____________________________________ Time: 08:48:13 AM PST US From: Rex Subject: Re: Kitfox-List: Tundra tyres. --> Kitfox-List message posted by: Rex Michel, As "skyflyte" suggests, if a tube fold is determined to be the cause of the flat spots, I believe the fold can be relieved with talcum powder during assembly and careful inflation technique. I know that inflating a tubed tire with the valve core out and letting it deflate at least once is a good practice to allow the tube to align itself inside the assembled rim and tire. Talcum powder (or the like) is required as an aid. This also can reduce valve stem stress if a tire were to rotate on the rim from the sudden rotational forces seen at landings. (especially if brakes are inadvertently applied during touchdown). I did a little Googling and here are some links of interest: http://www.aeroinstock.com/pdf/SpecMountTire.pdf http://www.planeandpilotmag.com/content/2004/sept/just_tires.html http://www.desser.com/tech/tiremount.html http://www.sheldonbrown.com/brandt/talcum.html I have never changed an aircraft or ATV tire, but have lots of experience with automobile, motorcycle and bicycle tires and tubes. It is common to see tires rotate and cause valve stem stress on dirt bikes and bicyces where low air pressures are used. Also be aware that extreme valve stem stress could result in an air leak. Talcum powder can prevent the tube from sticking to the tire if it were to rotate on the rim. Rex Florida skyflyte@comcast.net wrote: >--> Kitfox-List message posted by: skyflyte@comcast.net > >I have lumpy looking tires like that too! Mine are caused by the inner tube, which can fold over on itself due to the low inflation pressure. After I found out the cause, I quit worrying about it. > > > ________________________________ Message 14 ____________________________________ Time: 09:26:02 AM PST US From: "Randy Daughenbaugh" Subject: RE: Kitfox-List: Thrust - Over Rated? --> Kitfox-List message posted by: "Randy Daughenbaugh" I guess my main message is that to get the use of your horse power, you need rpm's. Horse power is rpm x torque. If your prop doesn't slip on take off and you have so much pitch in your prop that you can't get the rpm's up, you are not going to get good take off performance and good cruise at the same time. Mike Gibb's point about the variable pitch prop is right on, but I want to keep my plane LSA compliant. I seem to be getting older and want to fly a long time yet. Some props are more efficient than others. I am still looking. Randy . -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lowell Fitt Sent: Monday, May 08, 2006 8:58 PM Subject: Re: Kitfox-List: Thrust - Over Rated? --> Kitfox-List message posted by: "Lowell Fitt" Randy, No flames here. I have two friends that went to the PowerFin. They had the exact issues you had and eventually went to the shortened blades. They got the improvements you did. One is now with the Warp and doesn't know if he likes it. I think the other still has the Powerfin. They'll both be at the Cameron Park fly-in. I guess that is what the poor man's dyno was all about - finding the HP at the prop. Lowell ----- Original Message ----- From: "Randy Daughenbaugh" Sent: Monday, May 08, 2006 7:08 PM Subject: Kitfox-List: Thrust - Over Rated? > --> Kitfox-List message posted by: "Randy Daughenbaugh" > > > I have been seeing discussion of thrust lately and I think it is nearly > irrelevant. > > I have a PowerFin three blade prop on a 912S Series 5/7. When I first set > it up, static RPM was 5800 RPM. And MAN DID IT HAVE THRUST! The > acceleration would make your head snap back as you pushed the throttle in. > Well, it came time for first flight, and boy did it get off the ground > fast! > I don't have good numbers, but I am guessing about 150 feet ground roll. > BUT (you had to know that was coming), it would only fly about 65 - 70 mph > without over-reving the engine. > > So I put in more pitch on the prop. Got up to 85 mph. But lower static > rpm, less thrust and acceleration, longer ground roll. Added more pitch - > 95 mph, and less thrust. More pitch - WOT about 108 mph - cruise at 5500 > rpm about 96 mph - static rpm about 4900 rpm. But now ground roll on take > off approaching 500 ft. Spam can territory! > > PowerFin said they would shorten the prop 1" each blade. I finally took > them up on it, but it was a tough decision for me.... When I put it back > on > the plane, I added a degree and a quarter more pitch. Now I cruise at 106 > mph AND off the ground much quicker - maybe 275' solo. > > In short, if you want more thrust, all you have to do is sacrifice top > speed. Therefore, thrust is irrelevant. > > Indeed, it is more complicated than that. An "efficient" prop slips > enough > on take off to get the rpm up so that you can use most of your horse power > to get off the ground, but still has enough pitch so that you can get a > decent top speed. My plane is "over prop'ed" with the three blade > PowerFin. > I am saving my nickels for the Sensinich ground adjustable two blade. > > I would have written this earlier but was in Montana visiting my new > grandson and didn't have my flame suit with me. > > Randy - Everything in aviation is a compromise. > > . > > > ________________________________ Message 15 ____________________________________ Time: 12:51:23 PM PST US From: "kenneth schooley" --> Kitfox-List message posted by: "kenneth schooley" I have decided to sell my Kitfox 7-A kit. It is approx. 50% built for less than the kit cost originally. Located in San Diego area, but can arrange low cost shipping. 760-728-2450 ________________________________ Message 16 ____________________________________ Time: 12:51:23 PM PST US From: "ron schick" Subject: RE: Kitfox-List: Thrust - Over Rated? --> Kitfox-List message posted by: "ron schick" Yes Randy That is excactly the situation I am exploring. To get VW horsepower you need 3600 rpm. To pull a Kitfox you should have a 68" or more prop. To stay less than .8 mach at the tip of the prop requires a redrive. I have an ifa prop, but will not use it on my AW cert for sport applicability. This means finding the best combination of length and pitch to give a climb and cruise compromise. The VW direct drive has been critisized by some as lasy on climbout. For that reason I am concerned about thrust. Some think I should be concerned about using the VW. Don't worry I have flameproof shorts on so flame on. Ron NB Or >From: "Randy Daughenbaugh" >To: >Subject: RE: Kitfox-List: Thrust - Over Rated? >Date: Tue, 9 May 2006 10:24:28 -0600 > >--> Kitfox-List message posted by: "Randy Daughenbaugh" > > >I guess my main message is that to get the use of your horse power, you >need >rpm's. Horse power is rpm x torque. If your prop doesn't slip on take off >and you have so much pitch in your prop that you can't get the rpm's up, >you >are not going to get good take off performance and good cruise at the same >time. > >Mike Gibb's point about the variable pitch prop is right on, but I want to >keep my plane LSA compliant. I seem to be getting older and want to fly a >long time yet. Some props are more efficient than others. I am still >looking. > >Randy > >. > > >-----Original Message----- >From: owner-kitfox-list-server@matronics.com >[mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lowell Fitt >Sent: Monday, May 08, 2006 8:58 PM >To: kitfox-list@matronics.com >Subject: Re: Kitfox-List: Thrust - Over Rated? > >--> Kitfox-List message posted by: "Lowell Fitt" > >Randy, > >No flames here. I have two friends that went to the PowerFin. They had >the > >exact issues you had and eventually went to the shortened blades. They got >the improvements you did. One is now with the Warp and doesn't know if he >likes it. I think the other still has the Powerfin. They'll both be at >the > >Cameron Park fly-in. > >I guess that is what the poor man's dyno was all about - finding the HP at >the prop. > >Lowell >----- Original Message ----- >From: "Randy Daughenbaugh" >To: >Sent: Monday, May 08, 2006 7:08 PM >Subject: Kitfox-List: Thrust - Over Rated? > > > > --> Kitfox-List message posted by: "Randy Daughenbaugh" > > > > > > I have been seeing discussion of thrust lately and I think it is nearly > > irrelevant. > > > > I have a PowerFin three blade prop on a 912S Series 5/7. When I first >set > > it up, static RPM was 5800 RPM. And MAN DID IT HAVE THRUST! The > > acceleration would make your head snap back as you pushed the throttle >in. > > Well, it came time for first flight, and boy did it get off the ground > > fast! > > I don't have good numbers, but I am guessing about 150 feet ground roll. > > BUT (you had to know that was coming), it would only fly about 65 - 70 >mph > > without over-reving the engine. > > > > So I put in more pitch on the prop. Got up to 85 mph. But lower static > > rpm, less thrust and acceleration, longer ground roll. Added more pitch >- > > 95 mph, and less thrust. More pitch - WOT about 108 mph - cruise at >5500 > > rpm about 96 mph - static rpm about 4900 rpm. But now ground roll on >take > > off approaching 500 ft. Spam can territory! > > > > PowerFin said they would shorten the prop 1" each blade. I finally took > > them up on it, but it was a tough decision for me.... When I put it >back > > on > > the plane, I added a degree and a quarter more pitch. Now I cruise at >106 > > mph AND off the ground much quicker - maybe 275' solo. > > > > In short, if you want more thrust, all you have to do is sacrifice top > > speed. Therefore, thrust is irrelevant. > > > > Indeed, it is more complicated than that. An "efficient" prop slips > > enough > > on take off to get the rpm up so that you can use most of your horse >power > > to get off the ground, but still has enough pitch so that you can get a > > decent top speed. My plane is "over prop'ed" with the three blade > > PowerFin. > > I am saving my nickels for the Sensinich ground adjustable two blade. > > > > I would have written this earlier but was in Montana visiting my new > > grandson and didn't have my flame suit with me. > > > > Randy - Everything in aviation is a compromise. > > > > . > > > > > > > > > > > > > > > > > > > > > > > > > > > > _________________________________________________________________ FREE pop-up blocking with the new MSN Toolbar get it now! http://toolbar.msn.click-url.com/go/onm00200415ave/direct/01/ ________________________________ Message 17 ____________________________________ Time: 03:25:37 PM PST US From: "John Anderson" Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "John Anderson" Youre right Rick, fixed pitch are a compromise and some better than others. But I have to say, I seem to have stumbled on a beauty...3 blade 72" tapered tip Warpdrive. Good acceleration and 97kt cruise, I do have strut fairings, gap seals, exit fairing on the radiator and spats so I guess this all helps. But impressed as to how well that wee prop does. John A. From: "wingsdown" Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "wingsdown" If you have to turn the engine as fast or nearly so for take off as for fast flight, then an in-flight adjustable prop has merit. Even slow turning dinosaur engines for the most part have constant speed props. Band-Aids come in all shapes and sizes. Some are built right in and you never see them or for that matter know they are there. And are quite subjective as to definition. Rick -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Lowell Fitt Sent: Tuesday, May 09, 2006 7:05 AM Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "Lowell Fitt" Mike, I couldn't agree with you more. However there are airframe - engine - prop combinations that will give enough of each with a fixed pitch prop that the cost / benefit and complexity just hasn't made me even think about yet. In our airplanes, I think an argument could be made that a cockpit adjustable prop is sort of like a bandade for a mismatched engine - airframe. Personally I like the simplicity in flight and the lack of prop maintenane issues of the old fashioned ground adjustable Warp Drive prop. I can almost keep up with the PowerFin in climb and cruise has never been an issue for me, I can get plenty. Lowell ----- Original Message ----- From: "Michael Gibbs" Sent: Tuesday, May 09, 2006 12:48 AM Subject: Kitfox-List: Re: Thrust - Over Rated > --> Kitfox-List message posted by: Michael Gibbs > --> > > Randy sez: > >>In short, if you want more thrust, all you have to do is sacrifice top >>speed. Therefore, thrust is irrelevant. > > If you want more thrust AND more top speed, you get an in-flight > adjustable prop. You wouldn't drive your car in one gear all the > time, why operate your airplane that way? > > Mike G. > N728KF > > > > > > > > > > > > _________________________________________________________________ Read the latest Hollywood gossip @ http://xtramsn.co.nz/entertainment ________________________________ Message 18 ____________________________________ Time: 03:25:37 PM PST US From: kurt schrader Subject: Re: SV: Kitfox-List: Tundra tyres. --> Kitfox-List message posted by: kurt schrader Michel, I think the folded innertube problem is much like my tread seperation problem. Good suggestion. It could be that simple. 11 psi isn't much and the cold operations might be enough to spin the tires a little and roll up the innertube? Or pinched just from assembly? One thing to try is to blow them up to the max pressure for a bit, especially if it is warm that day. Taxi around and see if things stretch out. If not, do as was suggested and take a wheel apart and see if the innertube is creased. Put it back together with the powder so it can slip in place. Just an idea. Now I've got to go clean the wheat out of my 767 tires... ;-) Kurt S. --- Michel Verheughe wrote: > From: kurt schrader [smokey_bear_40220@yahoo.com] > > Have you seen any crop circles lately? ;-) > > Yes, concentric circles about the size of the > distance between the main gears of a B-767 and your > name was all over it! The Norwegian authorities are > being informed! :-) > > > I had a tire on my van where the tread looked > fine, but seperated internally and > > got a big flat spot. > > That could have happened to me too. I'll need to > look at it. But, Ron and Kurt, here a good analogy: > If you press hard with your thumb on the fabric of > your wing, you'll make a hollow that will come back > to normal after a time and/or with the help of heat. > > Well, my tyres are exactly the same, except that > they don't seem to come back to the normal smooth > and round shape. Since there is nothing visible on > the outside, maybe there is something damaged on the > inside. But I can't imagine what, when I look at the > inside of the old tyres. What do you think? > > Cheers, > Michel __________________________________________________ ________________________________ Message 19 ____________________________________ Time: 05:38:43 PM PST US From: kurt schrader Subject: Re: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: kurt schrader My flame suite on for another long one..... --------------------------------- > Randy sez: > > >In short, if you want more thrust, all you have to > >do is sacrifice top speed. Therefore, thrust is > >irrelevant. > ------------------------- > Mike G. > N728KF > If you want more thrust AND more top speed, you get > an in-flight adjustable prop. You wouldn't drive > your car in one gear all the time, why operate your > airplane that way? ---------------------------- Good point Mike, There is a misunderstanding on the list of thrust, HP and torque. The whole purpose of the prop is to convert power into thrust. Thrust is the most relevant measure. It moves the plane. But we are not talking about static thrust. You need the best thrust at the speed you are flying for best performance. Max static thrust is best at zero speed only. Max takeoff thrust is best somewhere around 1/2 your takeoff speed. Max climb thrust is best at climb speed. Max cruise thrust is best at.... ahhh you get it. A fixed pitch prop will give you its max thrust at only one speed. You are compromising only in that you pick the speed you want to have it perform best at. At all other speeds, faster or slower, it will give less then max thrust. A variable or constant speed prop will still have one best speed, but the curve will be flatter. It will perform almost as well at all speeds as a fixed pitch prop for its one speed. Say a cruise fixed pitch gives efficiencies of: 50% in takeoff 75% in climb 85% in cruise A climb prop might give: 65% in takeoff 85% in climb 80% in cruise The variable prop might give: 75% in takeoff 82% in climb 83% in cruise I have a friend who has a Champ product, his 3rd in 2 years. His 150 HP constant speed Champ would perform equal to his 180 HP fixed pitch Champ, except around one speed. That speed depended upon which fixed pitch prop he installed. He might get better climb, but equal cruise, or better cruise, but equal climb from the extra 30 HP. In his case, he used the prop that meant they cruised equally, but the fixed pitch climbed better with the 30 more HP. If it had a constant speed prop, it would have used the 30 extra HP for better performance all across the speed range. His fixed pitch got off the ground better, but burned more for the same cruise speed. Another way to say it is that the variable prop was almost worth the 30 extra HP. This is my problem with static thrust measurements. It only gives you the measurement for the best prop at no speed. How useful is that? I think that is what Randy was saying. Static thrust is only good when static. It is already losing performance in the takeoff roll, but not so badly as when at cruise speed. A cruise prop would be poor but increasing performance in the takeoff roll, and continue to get better all the way up to cruise. The climb prop is of course in between, getting better, then getting worse as speed increases. As to HP and torque, if you are swinging a 2x4 around with your engine, it will take HP and torque to do, but produce no thrust. If you have a feathered prop, it will take lots of HP and torque to swing and still produce no thrust. The efficiency of the prop to produce thrust is what makes the hp and torque meaningful. As a prop increases pitch, it moves more toward a feathered prop in that the angle of lift of the prop is more against torque and less forward producing thrust. Lift of the prop is always about 90 degrees to the blade. A pitch of say 20 degrees means that some of the prop's lift is pulling air in a circle and not just pushing it back. That takes HP. When I flew the C-130, the pitch could be as high as 55 degrees in cruise. More than 1/2 the HP went to spinning the air and less than 1/2 went to thrust. Our props don't get that bad due to our less pitch. But a heavily pitched prop may take the same HP/torque as a finer pitched prop at higher RPM. The faster turning, lower pitched prop will produce more thrust, to a point. That point is determined by the most efficient rpm for the prop compared to mach number, and the most efficient rpm for the engine. Those 2 may not match. A less efficient prop may take more HP or torque to give the same performance, not more. A more efficient prop will give more thrust with the same HP/torque. HP and torque don't tell the whole story. They don't give thrust, except as the prop allows. So I am saying this. The prop that produces the most thrust will be the one that has its best speed closest to your engine's favorite RPM, but does it at the speed you are flying. Also it has to be the most aerodynamically efficient. Max static thrust equals first gear only. Takeoff props equal second gear. Climb props equal third gear. Cruise props are overdrive. Variable props are automatic trannys. That is Mike's point. The actual performance of the plane will be determined by just how much thrust it can produce today on this fuel, at this temp, at this density altitude, with this prop, at this speed, with these sparkplugs, at this rpm and manifold setting..... You can measure all that, or you can just measure thrust. So thrust is really the key, but it has to be measured now, at your speed and with all variables. Static thrust is good for fans, not planes. Thrust is what happens after all the variables are in place. HP and torque are only what you are putting into a prop, not what is coming out, which changes with prop efficiency, speed, air density..... So that is why I wanted a meter that simply measures the thrust output on board at all speeds, altitudes, settings, etc. It will tell you what performance you are getting now, whatever now is. And instead of HP, you can simply measure fuel flow if the engine is tuned right. That is, if the fuel air ratio is the same, fuel in equals power out. That you can compare to whatever you want to change and see if it made things better or worse. 10% more thrust with the same fuel flow is 10% better no matter how you got it. 10% more HP or 10% more torque might just mean a 10% worse prop is giving equal thrust for more gas. Bottom line: Thrust = performance. Fuel flow = energy and $ in to produce the thrust. The best prop will be the one that gives you the most thrust per fuel flow at the speed you want it. A fixed pitch will peak at a given speed with a strong curve. A variable prop will have a broader curve. You have to pick the prop that peaks at the speed and rpm that best matches your engine and most important performance goal. This is critical for fixed pitch, but less critical for variable. Then you can compare one prop against another to see which gives the most thrust at the same fuel flow. Is this too much at once? Hope it can be understood. You want thrust. Thrust moves the plane. We just aren't use to measuring it directly. Fuel flow is what we pay to get it and max fuel flow is how much power is available under present conditions. One day I will simplify this..... Kurt S. S-5 flying and 1/2 done. __________________________________________________ ________________________________ Message 20 ____________________________________ Time: 05:50:21 PM PST US From: kurt schrader Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: kurt schrader Well John, Rick does understand props and engines. But you've done great too, having picked and built all that stuff yourself. What engine and prop RPM are you using? What fuel flow for takeoff and cruise? Inquiring minds want to know. ;-) Especially since some of us have the same blades, just cockpit adjustable and maybe different rpms. Hard to actually compare on different planes, I know, but it helps a little. Kurt S. --- John Anderson wrote: > You're right Rick, fixed pitch are a compromise and > some better than others. > But I have to say, I seem to have stumbled on a > beauty...3 blade 72" tapered > tip Warpdrive. Good acceleration and 97kt cruise, I > do have strut fairings, > gap seals, exit fairing on the radiator and spats so > I guess this all helps. > But impressed as to how well that wee prop does. > John A. > > From: "wingsdown" > To: > Subject: RE: Kitfox-List: Re: Thrust - Over Rated > Date: Tue, 9 May 2006 07:27:04 -0700 > > --> Kitfox-List message posted by: "wingsdown" > > > If you have to turn the engine as fast or nearly so > for take off as for > fast flight, then an in-flight adjustable prop has > merit. Even slow > turning dinosaur engines for the most part have > constant speed props. > Band-Aids come in all shapes and sizes. Some are > built right in and you > never see them or for that matter know they are > there. And are quite > subjective as to definition. > > Rick __________________________________________________ ________________________________ Message 21 ____________________________________ Time: 06:55:38 PM PST US From: Fred Shiple Subject: Kitfox-List: 912S/ oil cooler efficiency --> Kitfox-List message posted by: Fred Shiple I've a question regarding oil cooler efficiency on a Kitfox with a 912S: My Series 6/ 912S was built with the Skystar optional oil cooler. During the past two summers at temps over 95F I'd have to lower the nose after talk off/climb after about 1 to 1 1/2 minutes as oil temp reached 260F (red line 266F). At 100F (a rare occurance in NW Ohio) had to throttle back from 75% to 65% for the same reason. Now that I'm flying on floats, I've begun to see the same thing at 75-80 degrees. I'm flying 12-15 mph slower (at the same rpm/manifold pressures) as anticipated with the extra drag. The water and cylinder head temps have remained well in the green with or without the floats. I saw temps consistant with prior years operations in the month prior to install of the floats two weeks ago. Any advice is appreciated as I'm now concerned about warmer weather operation. Fred ________________________________ Message 22 ____________________________________ Time: 06:55:39 PM PST US From: "Clem Nichols" Subject: Kitfox-List: Thrust...Overrated? --> Kitfox-List message posted by: "Clem Nichols" This is a little apart from the question of thrust, but of parallel = interest in the sense that it has to do with airplane performance. I = gather that most Kitfoxers use 3-bladed props just as I do, but it's my = understanding (perhaps incorrectly) that the more blades a prop has the = less efficient it is. I know that Randy Schlitter who manufactures the = Rans S6S, a plane much like the Kitfox, provides a 2-blade wooden prop = with his kits, and states in his literature that (in his opinion, at = least) he's never seen a 3-blade prop that works better than a 2-blade = one. (I hope I haven't misquoted him on this. I couldn't find the = brochure to check against my memory). I realize the 3-blade by virtue = of being shorter in diameter is less likely to strike the ground in a = botched tail-dragger landing. I was just wondering if anyone in the = group is using a 2-blader, and if so, what their opinion is of it. Kurt, your message on thrust was most enlightening. Clem Nichols ________________________________ Message 23 ____________________________________ Time: 07:26:38 PM PST US From: John King Subject: Re: Kitfox-List: 912S/ oil cooler efficiency --> Kitfox-List message posted by: John King Fred, I have a Series 6 powered by a 912S and haven't had excessively high oil temperatures in hot weather. Have you calibrated your oil temperature sensor against a standard or accurate gauge? Send me a picture of your oil cooler inlet on the cowling. and the dimensions of the oil cooler. I'll make a comparison with mine and send you a picture of my configuration. -- John King Warrenton, VA Fred Shiple wrote: >--> Kitfox-List message posted by: Fred Shiple > >I've a question regarding oil cooler efficiency on a Kitfox with a 912S: >My Series 6/ 912S was built with the Skystar optional oil cooler. During the past two summers at temps over 95F I'd have to lower the nose after talk off/climb after about 1 to 1 1/2 minutes as oil temp reached 260F (red line 266F). At 100F (a rare occurance in NW Ohio) had to throttle back from 75% to 65% for the same reason. >Now that I'm flying on floats, I've begun to see the same thing at 75-80 degrees. I'm flying 12-15 mph slower (at the same rpm/manifold pressures) as anticipated with the extra drag. The water and cylinder head temps have remained well in the green with or without the floats. I saw temps consistant with prior years operations in the month prior to install of the floats two weeks ago. >Any advice is appreciated as I'm now concerned about warmer weather operation. >Fred > > > > ________________________________ Message 24 ____________________________________ Time: 08:22:11 PM PST US From: "John Anderson" Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: "John Anderson" Early days on fuel flow but seems to be around 15 litres per hour and I don't have a flow meter. 4500 on t/o, more there if I want with prop setting but that's what I use, climb 1200fpm. 97kts at 4300. Just me in it tho at this early stage. John From: kurt schrader Subject: RE: Kitfox-List: Re: Thrust - Over Rated --> Kitfox-List message posted by: kurt schrader Well John, Rick does understand props and engines. But you've done great too, having picked and built all that stuff yourself. What engine and prop RPM are you using? What fuel flow for takeoff and cruise? Inquiring minds want to know. ;-) Especially since some of us have the same blades, just cockpit adjustable and maybe different rpms. Hard to actually compare on different planes, I know, but it helps a little. Kurt S. --- John Anderson wrote: >You're right Rick, fixed pitch are a compromise and >some better than others. >But I have to say, I seem to have stumbled on a >beauty...3 blade 72" tapered >tip Warpdrive. Good acceleration and 97kt cruise, I >do have strut fairings, >gap seals, exit fairing on the radiator and spats so >I guess this all helps. >But impressed as to how well that wee prop does. >John A. > >From: "wingsdown" >To: >Subject: RE: Kitfox-List: Re: Thrust - Over Rated >Date: Tue, 9 May 2006 07:27:04 -0700 > >--> Kitfox-List message posted by: "wingsdown" > > >If you have to turn the engine as fast or nearly so >for take off as for >fast flight, then an in-flight adjustable prop has >merit. Even slow >turning dinosaur engines for the most part have >constant speed props. >Band-Aids come in all shapes and sizes. Some are >built right in and you >never see them or for that matter know they are >there. And are quite >subjective as to definition. > >Rick __________________________________________________ _________________________________________________________________ Find the coolest online games @ http://xtramsn.co.nz/gaming ________________________________ Message 25 ____________________________________ Time: 08:23:43 PM PST US From: Fred Shiple Subject: Re: Kitfox-List: 912S/ oil cooler efficiency --> Kitfox-List message posted by: Fred Shiple John, I calibrated it two years ago when it was installed (boiling water). Will get picks and measurements to you tomorrow. Fred temperatures in hot weather. Have you calibrated your oil temperaturesensor against a standard or accurate gauge? Send me a picture of your ________________________________ Message 26 ____________________________________ Time: 08:30:57 PM PST US Subject: Kitfox-List: Re: Elevator hinge tab question?? From: "darinh" --> Kitfox-List message posted by: "darinh" Thanks to all who responded. I have solved the problem using a nifty little gadget I picked up at the local Lowe's. It is a flexibly drill shaft. I simply installed a 13/64 bit and drilled out the elevator tabs to allow for 1/32" oversized hole. The elevator went together excellent and works great! Thanks again, Darin Read this topic online here: http://forums.matronics.com/viewtopic.php?p=33749#33749