---------------------------------------------------------- Kitfox-List Digest Archive --- Total Messages Posted Wed 05/04/05:14 ---------------------------------------------------------- Today's Message Index: ---------------------- 1. 04:49 AM - Rotax 912S exhaust system - Ball Joints (kitfoxjunky) 2. 06:08 AM - altimeter (jareds) 3. 06:41 AM - Re: toe-in (again) (Lowell Fitt) 4. 07:52 AM - Re: SV: Fiberglass tail spring (kerrjohna@comcast.net) 5. 08:16 AM - Out flying the prop .Re: Is lugging the engine bad? (Randy Daughenbaugh) 6. 08:58 AM - Re: altimeter (AlbertaIV@aol.com) 7. 11:50 AM - Re: toe-in (again) (Marco Menezes) 8. 12:03 PM - Re: Hard Landing, was brakes (Mark Scott) 9. 12:41 PM - Fuel Consumption (Alan Daniels) 10. 03:12 PM - Re: Hard Landing, was brakes (customtrans@qwest.net) 11. 04:20 PM - Re: toe-in (again) (Allan Arthur) 12. 06:39 PM - Re: Rotax 912S exhaust system - Ball Joints (N55XS) 13. 09:15 PM - Re: toe-in (again) (jimshumaker) 14. 09:32 PM - Re: toe-in (again) (Steve Cooper) ________________________________ Message 1 _____________________________________ Time: 04:49:02 AM PST US From: kitfoxjunky Subject: Kitfox-List: Rotax 912S exhaust system - Ball Joints 07:48:19 AM, Serialize complete at 05/04/2005 07:48:19 AM --> Kitfox-List message posted by: kitfoxjunky In the past my exhaust system has been problematic..cracking. May be due to my not getting all the stress out of it when I re-assembled it..but I have heard others have had the same problem. Ran into a fellow who had similar problems until he put ball joints in the system. Has anyone on the list had experience in this area? Looks like they are only going to cost about $ 150. Gary Walsh Kitfox IV C-GOOT ________________________________ Message 2 _____________________________________ Time: 06:08:14 AM PST US From: jareds Subject: Kitfox-List: altimeter Gecko/20040804 Netscape/7.2 (ax) --> Kitfox-List message posted by: jareds Does experimental class require that all the instrements be checked by someone certified. Now that i dont have a transponder the altimeter is the only one I'm worried about and that was checked 2 years ago? With my repairmans certificate can i just sign off that condition inspection was complete (including everything) until i'm able to fly over to a repair station to have altimeter calibrated? Thanks Jared ps First flight yesterday with my new engine (rebuilt) went wonderfully!!! ________________________________ Message 3 _____________________________________ Time: 06:41:07 AM PST US From: "Lowell Fitt" Subject: Re: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: "Lowell Fitt" Marco, In my experience, you hit it right on the head. At least in my case, the axle did bend. I knew that because of the need to shim the brake caliper. I took care of the alignment with a couple of washers in the right place on the caliper mounting bolts. The weldment might have bent also, but I don't know how to determine that. I believe someone on the list tweeked the weldment using a massive wrench on the weldment itself. Without a doubt though, ground handling can be quite a chore with toe-in. Regarding the FAA inspection, they will not have any idea of toe in unless you tell them. I doubt they would be looking for that, so the adjustment could be done later if you schedule demanded it. ----- Original Message ----- From: "Marco Menezes" Subject: Kitfox-List: toe-in (again) > --> Kitfox-List message posted by: Marco Menezes > > Just when you think everything's ready . . . Lola has a visible bilateral > toe-in condition. She has the standard tube gear. I put 200# of dead > weight in her and it made little difference. I want to correct this before > the FAA gets here for airworthiness inspection but am more than a little > apprehensive about putting the cheater bar to axle to bend the gear > weldment. From reviewing the archives, it looks like this is more likely > to bend the mild steel axle then the weldment. I'm guessing that a bent > axle would likely muck up the disk/pad brake alignment. > > I'd appreciate some details from you guys that have done this and > succeeded. > > Thanks much. > > Marco Menezes > KF 2 N99KX > > > ________________________________ Message 4 _____________________________________ Time: 07:52:52 AM PST US From: kerrjohna@comcast.net Subject: Re: SV: Kitfox-List: Fiberglass tail spring --> Kitfox-List message posted by: kerrjohna@comcast.net I believe that Grove offered a fiberglass tail spring at one time but removed it from the market because a standard layup could not withstand the torsional loads imposed. Does anyone have additional information regarding this? John Kerr -------------- Original message -------------- > --> Kitfox-List message posted by: Michel Verheughe > > willett wrote: > > Why not a carbon fiber spring? > > I think carbon fiber will have a better weight to strength ratio, Mike. But is > weight so much of a problem? I think the most important factor would be to > mould (carbon or glass) under vacuum. Air bubbles and uneven distribution of > the fiber and resin is, IMHO, a danger for tensile strength. > > Cheers, > Michel > > > > > > I believe that Grove offered a fiberglass tail spring at one time but removed it from the market because a standard layup could not withstand the torsional loads imposed. Does anyone have additional information regarding this? John Kerr -------------- Original message -------------- -- Kitfox-List message posted by: Michel Verheughe willett wrote: Why not a carbon fiber spring? I think carbon fiber will have a better weight to strength ratio, Mike. But is weight so much of a problem? I think the most important factor would be to mould (carbon or glass) under vacuum. Air bubbles and uneven distribution of the fiber and resin is, IMHO, a danger for tensile strength. Cheers, Michel 7-Day Browse, Chat, FAQ, ________________________________ Message 5 _____________________________________ Time: 08:16:21 AM PST US From: "Randy Daughenbaugh" Subject: Out flying the prop .RE: Kitfox-List: Is lugging the engine bad? --> Kitfox-List message posted by: "Randy Daughenbaugh" Bob, Yup, I guess that is what I am doing. Out flying the prop. !! In climb at about 70 mph I am getting 5600 rpm. But static is 5000 RPM. Using Alan Daniels yard stick of half a pound of fuel per hour per horse power, I am burning about 3 gph (maybe less!) at cruise at 97 MPH airspeed and 5500 RPM. Cranking that through says that I am using about 36 hp at cruise. No wonder cruise is slow. It is sounding to me like I have the wrong propeller. Thanks for your comments! Randy . -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of aerocon1@telusplanet.net Subject: RE: Kitfox-List: Is lugging the engine bad? --> Kitfox-List message posted by: aerocon1@telusplanet.net Randy, After recieving your latest information...i.e. your ability to over-rev at full throttle in level flight I will have to say you are not lugging the engine. I thought you were only able to get 5500 at WOT in level flight. I guess we didn't have enough information. It appears that you being limited to get 5000rpm WOT static rpm yet are able to over-rev the engine at full throttle in level flight is a combination of airframe and prop design. Clean airframes commonly "out fly" their fixed pitch prop. Our Titan does it regularily. We have to set the prop quite course because the plane is so clean it will easily outfly the prop. The propeller design also has a lot to do with the range of prm the engine operates at. In short, I'd guess, in your case, the prop design has more to do with the low static rpm and high level flight WOT rpm. What WOT rpm to you atain at climb attitude? As long as you don't over-rev in climb it sounds like you are in good shape. I hope the above makes sense. regards.. Bob R Quoting Randy Daughenbaugh : > --> Kitfox-List message posted by: "Randy Daughenbaugh" > > > I appreciate all the comments - Bob and all! But I need to clear something > up. > > At present settings, I can easily over rev the engine - 6000 +RPM - in level > flight. I don't have a good number on what air speed this gives me, but I > would guess it is about 115 mph. BUT this also gives me a 5000 RPM WOT on > the ground. This is what raises the "lugging the engine" issue. > > From some comments, it sounds like I still don't have enough pitch. > > I am still absorbing some of the comments. Thanks again. > > Randy > > . > > > -----Original Message----- > From: owner-kitfox-list-server@matronics.com > [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of Bob Robertson > To: kitfox-list@matronics.com > Subject: Re: Kitfox-List: Is lugging the engine bad? > > --> Kitfox-List message posted by: "Bob Robertson" > > > Hi Randy, > A while ago I spoke with Eric Tucker of Kodiak Research re the 912 series of > engines. His response to lowering the piston wear was to run the engine > close to 5500 rpm at cruise. He related that this seems to be an ideal rpm > to run this high compression engine. > The design of your prop and the cleanliness of your airframe will have a lot > to do with the max WOT rpm you can get. > If you can only get 5500 rpm at WOT in level flight I would say that you are > slightly over pitched. It would be better to back off the pitch a bit so > you can get, say, 5700-5800 rpm max in level flight at WOT. > You will be wasting a little fuel by drawing down the engine rpm with the > prop. > If your airframe is comparable to other series 7's and your weight is in > line with other identical planes, I'd start looking at the design of the > prop if you are not attaining the same level of performance as other similar > planes.... You have to compare apples to apples here though.... > just my two cents > > Bob Robertson > Light Engine Services Ltd. > Rotax Service Center > St. Albert, Ab. T8N 1M8 > Ph: (Tech Support) 1-780-418-4164 > Ph: (Order Line) 1-866-418-4164 (TOLL FREE) > www.rtx-av-engines.ca > > > ----- Original Message ----- > From: "Randy Daughenbaugh" > To: > Subject: Kitfox-List: Is lugging the engine bad? > > > > --> Kitfox-List message posted by: "Randy Daughenbaugh" > > > > > > > I have been trying to get a higher cruise speed by adding more pitch to my > > prop. For background, I have a Series 5 with Series 7 firewall forward > (I > > think that for practical purposes, this makes it a Series 7 with 912S and > a > > 72" Powerfin "F" prop. > > > > I have reached a point that gives me 5000 rpm at Wide Open Throttle on the > > ground. This only gives me a 108 mph cruise speed at 5500 rpm. I still > get > > off the ground fast and climb at 900 fpm solo at 5000 ft. > > > > BUT, I have been told that it is hard on the engine to give it full > throttle > > at 5000 rpm. That "lugging" the engine like this will hurt it. I am not > > too concerned since my strip is at 4400' and high manifold pressure at > this > > altitude is still not too high. > > > > But will this hurt my engine? Is "lugging" with too much pitch in the > prop > > bad? > > > > Randy - A CAP in my future? > > > > > > > > > > > ________________________________ Message 6 _____________________________________ Time: 08:58:44 AM PST US From: AlbertaIV@aol.com Subject: Re: Kitfox-List: altimeter --> Kitfox-List message posted by: AlbertaIV@aol.com In a message dated 5/4/2005 9:10:22 AM Eastern Standard Time, jareds@verizon.net writes: Does experimental class require that all the instrements be checked by someone certified. Now that i dont have a transponder the altimeter is the only one I'm worried about and that was checked 2 years ago? With my repairmans certificate can i just sign off that condition inspection was complete (including everything) until i'm able to fly over to a repair station to have altimeter calibrated? Thanks Jared Jared, As far as I know, there is no requirement to have the instruments calibrated by anyone (VFR). As repairman, you can simply sign off the airplane and keep on gettin on. That included airframe, engine and all. There may be a calibration required for instrument flying but I don't have an instrument rating so was never concerned. Don Smythe Classic IV w/ 582 ________________________________ Message 7 _____________________________________ Time: 11:50:24 AM PST US From: Marco Menezes Subject: Re: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: Marco Menezes Thanks, Lowell. After disassembling the R main wheel and re-reading the construction manual it occurred to me, as you said, that the bent axle problem might be corrected by shimming the caliper as needed. It also occurred to me after removing the axle that the gear weldment might be bent by sticking the cheater bar through the hole formerly occupied by the axle, and reefing mightily. If this successfully cured toe-in, it would spare the axle and so eliminate the need to monkey with the brakes. Then I read Skystar's service letter on need to inspect tube gears for cracks and bends that may lead to gear failure!! There seem to be 2 schools on this: Bend the axle or bend the gear weldment. Denny-Skystar seem to have taken both positions over the years. Marco Menezes KF 2 - N99KX Lowell Fitt wrote: --> Kitfox-List message posted by: "Lowell Fitt" Marco, In my experience, you hit it right on the head. At least in my case, the axle did bend. I knew that because of the need to shim the brake caliper. I took care of the alignment with a couple of washers in the right place on the caliper mounting bolts. The weldment might have bent also, but I don't know how to determine that. I believe someone on the list tweeked the weldment using a massive wrench on the weldment itself. Without a doubt though, ground handling can be quite a chore with toe-in. Regarding the FAA inspection, they will not have any idea of toe in unless you tell them. I doubt they would be looking for that, so the adjustment could be done later if you schedule demanded it. ----- Original Message ----- From: "Marco Menezes" Subject: Kitfox-List: toe-in (again) > --> Kitfox-List message posted by: Marco Menezes > > Just when you think everything's ready . . . Lola has a visible bilateral > toe-in condition. She has the standard tube gear. I put 200# of dead > weight in her and it made little difference. I want to correct this before > the FAA gets here for airworthiness inspection but am more than a little > apprehensive about putting the cheater bar to axle to bend the gear > weldment. From reviewing the archives, it looks like this is more likely > to bend the mild steel axle then the weldment. I'm guessing that a bent > axle would likely muck up the disk/pad brake alignment. > > I'd appreciate some details from you guys that have done this and > succeeded. > > Thanks much. > > Marco Menezes > KF 2 N99KX > > > --------------------------------- ________________________________ Message 8 _____________________________________ Time: 12:03:25 PM PST US From: "Mark Scott" Subject: RE: Kitfox-List: Hard Landing, was brakes --> Kitfox-List message posted by: "Mark Scott" Just a thought about this whole gear discussion. I am not flying a fox yet so take this with a grain of salt. One of my expectations of the landing gear (besides holding the airplane up off the ground) is that it absorb the energy in a landing, especially if it's a bad one. Speaking from an engineering standpoint, I would not want to see a gear that could take any abuse thrown at it without deforming, as this indicates to me that it will completely transfer that energy to the supporting structure. I would rather see one that can handle the normal everyday loads plus some reasonable safety factor, but beyond that will begin to deform and absorb energy rather than transfer it to the rest of the structure (or my spine). Typically (and I am generalizing here), welded tube structures are good at absorbing impact energy (look at driver's cage in a race car). -- ________________________________ Message 9 _____________________________________ Time: 12:41:27 PM PST US From: Alan Daniels Subject: Kitfox-List: Fuel Consumption --> Kitfox-List message posted by: Alan Daniels I did some checking and found I was only partially correct in the numbers I gave you. Rotax says that the 912s has a specific fuel consumption of .47 lb/hph , but this in only at max. continuous power which they say is 6.6 gal. per hour. That works out to 84 HP. But they also say that to get 75 HP it takes 4.9 GPH and that works out to only .392 lb/hph. To get 100 HP it takes 7.1 GPH or .426 lb/hph. So what this means is that you pay 1.7 GPH to go from 75 to 84 HP. This is of course needed in some climb conditions but it eats a lot of gas in cruise. These numbers are the best Rotax could get with a perfect engine so we are not getting better. It looks like for mid power setting you should use .4 lb/hph for figuring power until you get over 75 or 4.9 GPH and then I don't have any idea how the curve gets to 6.6 GPH. I would like to see a chart of RPM and MP combinations required to get different HP. I guess this is a long winded way of saying that if you are not using about 5 GPH you are not using 75 HP. Real world flying I use about 4.5 GPH just having fun flying local, but a trip I took that was just about 2000 miles where I was trying to make time and bucking headwinds and bad weather and going over the rockies. I divided my fuel by the hobbs and came up with 5.7 GPH. If your are planing a long trip you might keep that in mind in flight planning until you find what you are actually burning so you don't come up short. Alan ________________________________ Message 10 ____________________________________ Time: 03:12:22 PM PST US From: customtrans@qwest.net Subject: RE: Kitfox-List: Hard Landing, was brakes --> Kitfox-List message posted by: customtrans@qwest.net Mark, All I can say is the Grove gear is a spring gear, thus it should spring or bend on a hard landing. I actually watched the gear on a landing and you can see it flex. steve a -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com]On Behalf Of Mark Scott Subject: RE: Kitfox-List: Hard Landing, was brakes --> Kitfox-List message posted by: "Mark Scott" Just a thought about this whole gear discussion. I am not flying a fox yet so take this with a grain of salt. One of my expectations of the landing gear (besides holding the airplane up off the ground) is that it absorb the energy in a landing, especially if it's a bad one. Speaking from an engineering standpoint, I would not want to see a gear that could take any abuse thrown at it without deforming, as this indicates to me that it will completely transfer that energy to the supporting structure. I would rather see one that can handle the normal everyday loads plus some reasonable safety factor, but beyond that will begin to deform and absorb energy rather than transfer it to the rest of the structure (or my spine). Typically (and I am generalizing here), welded tube structures are good at absorbing impact energy (look at driver's cage in a race car). -- ________________________________ Message 11 ____________________________________ Time: 04:20:58 PM PST US From: Allan Arthur Subject: Re: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: Allan Arthur Marco, I straightened the tube gear on my Series 5. I used a 6 foot steel pipe with a "floor flange" threaded on one end. I notched the flange cutting into two adjacent holes. Tape the axle to protect it and slip the flange end over the axle. Then take all the slack out of the system by pulling the pipe forward. Wrap steel wire (probably no. 16 or 18) around the pipe thru one notch around in front of and to the inside of the gear over a bolt and back thru the other notch and around the pipe. Make about 50 tight turns. This captures the gear to the pipe and will take the bending load off the axle during the bending action. I clamped two 2x4's to the top of the gear where they attach to to fuselage extending back toward the tail about 6 feet.. Then attach a "come along" between the end of the 2x4's and the steel pipe. I attached a laser level to the pipe such that the spot was on a cardboard screen near the other gear. Then bend the gear a few degrees and release and see if the spot returns to the starting position. Then bend a little more and release. BE CAREFUL THERE IS A LOT OF STORED ENERGY IN THE GEAR LEG WHEN BENT!! I had to bend the gear around 20 degrees until I noticed that the gear was beginning to yield and the spot did not quite return to the starting position. Continue until the spot has moved by the amount of correction that you want in the released condition. It worked for me, but I don't guarantee that the gear won't break. If this description is not clear you can call me at (925) 932-1398. Allan & Nancy Arthur, N40AA Kitfox Series 5, (912S, Warpdrive 3 blade) Byron Airport (C83), Hangar C8 On May 3, 2005, at 6:32 PM, Marco Menezes wrote: > --> Kitfox-List message posted by: Marco Menezes > > Just when you think everything's ready . . . Lola has a visible > bilateral toe-in condition. She has the standard tube gear. I put 200# > of dead weight in her and it made little difference. I want to correct > this before the FAA gets here for airworthiness inspection but am more > than a little apprehensive about putting the cheater bar to axle to > bend the gear weldment. From reviewing the archives, it looks like > this is more likely to bend the mild steel axle then the weldment. I'm > guessing that a bent axle would likely muck up the disk/pad brake > alignment. > > I'd appreciate some details from you guys that have done this and > succeeded. > > Thanks much. > > Marco Menezes > KF 2 N99KX > > ________________________________ Message 12 ____________________________________ Time: 06:39:44 PM PST US From: N55XS Subject: Re: Kitfox-List: Rotax 912S exhaust system - Ball Joints --> Kitfox-List message posted by: N55XS kitfoxjunky wrote: >--> Kitfox-List message posted by: kitfoxjunky > >In the past my exhaust system has been problematic..cracking. May be due >to my not getting all the stress out of it when I re-assembled it..but I >have heard others have had the same problem. Ran into a fellow who had >similar problems until he put ball joints in the system. Has anyone on >the list had experience in this area? Looks like they are only going to >cost about $ 150. > >Gary Walsh >Kitfox IV >C-GOOT > > > Gary, While not a Kitfox owner/builder (I'm currently building a Europa XS), we do share a common engine, the Rotax 912S. I enjoy this site, mainly because of the helpful folks and the fact that I may consider the "Fox" as my next build. As fitted to the Europa, the exhaust system has ball joints that join the muffler to the down pipes. I've heard of no problems with the arrangment. As a matter of fact, I just installed mine, today. If you'd like to see the arrangment, go to http://www.n55xs.com and look at today's entrys. -- Jeff - A055 Only FWF to finish up... Builders Log: http://www.N55XS.com -- ________________________________ Message 13 ____________________________________ Time: 09:15:58 PM PST US From: "jimshumaker" Subject: Re: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: "jimshumaker" Marco I straightened my gear very simularly to Alan. But I used a 3 foot pipe wrench with a 2 inch by 8 foot cheater over the handle. I padded the jaws of the wrench with hardwood. I did NOT go onto the axle. The wheels and tires stayed on the plane. Wrench went on the inside of the grear on the axle tube. Jim Shumaker ________________________________ Message 14 ____________________________________ Time: 09:32:13 PM PST US From: "Steve Cooper" Subject: RE: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: "Steve Cooper" I slid the bar through the axle in order to Cold Bend mine 1.5 degrees Toe Out. Worked VERY well. -----Original Message----- From: owner-kitfox-list-server@matronics.com [mailto:owner-kitfox-list-server@matronics.com] On Behalf Of jimshumaker Subject: Re: Kitfox-List: toe-in (again) --> Kitfox-List message posted by: "jimshumaker" Marco I straightened my gear very simularly to Alan. But I used a 3 foot pipe wrench with a 2 inch by 8 foot cheater over the handle. I padded the jaws of the wrench with hardwood. I did NOT go onto the axle. The wheels and tires stayed on the plane. Wrench went on the inside of the grear on the axle tube. Jim Shumaker