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RE: H9 Piper Pawnee or the new H9 RV-8 ?
I have the Pawnee. It has been my trainer and has held up well to all the abuse I can give it. It is a joy to fly. The attachment did come loose on the left wing. Fortunately, the struts held the wing on. I have attached a drawing of the attachment stick (to scale), which reminds me of a popsicle stick. It is made of liteply and mine came loose at the first rib as well as cracked where it necks down. I suggest making it of 3/32 or 1/8 aircraft ply, at least the long part. The doubler can be liteply. I thought about putting a balsa filler between the narrow tongue and the bottom sheeting, but reconsidered that maybe the design was intended to be flexible to allow the metal bolt to pull the inserted part against the fuselage. An alternative would be to just add a stopper block on top of the doubled section and against the root rib, but not necessarily glued to the root rib. That suggestion is shown in blue as "retainer reinforcement." John [image][/image]
Posted on: 11/3/2009 2:22 PM by Author "jpanhalt"
in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=9225385
RE: Hangar 9 40 Size Piper Pawnee!!!
Here's the picture of the modified gear mentioned above after a hard day's flying. John [image]http://www.rcuniverse.com/forum/post.asp?do=reply&messageID=9211100&toStyle=tm#[/image]
Posted on: 10/29/2009 4:05 PM by Author "jpanhalt"
in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=9212788
RE: Hangar 9 40 Size Piper Pawnee!!!
I have done something very similar to what rv9-a suggests. It seems we have all discovered that the front cross-bar bends with a medium hard landing. First, I cut the smaller cross-wire loose. Then, I added a 5/32 doubler between the two mounting straps. I then put a piece of slit fuel tubing over the smaller cross-wire and tied it to the doubler with soldered brass straps. It allows just a little give and has been working for lots of hard landings since. Everything is packed and ready to go for tomorrow, so I can't get picures tonight. I will post some tomorrow after flying. John
Posted on: 10/28/2009 7:19 PM by Author "jpanhalt"
in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=9210423
RE: Hangar 9 40 Size Piper Pawnee!!!
I like my Pawnee 40 too and would like to share come comments for potential newbies. I am a newbie to powered flight, but had been flying sailplanes for the past 15 years or so, including some high performance ones. The Pawnee was and still is my trainer. I have been flying it for about 2 months. [u]Build[/u]: Used Hitec 225's on wing and elevator halves (2). Put the elevator servos in the tail cone with direct linkages. Dubro tail wheel. OS Surpass 70 engine. Fuel tank about 1.5 to 2" back,i.e., about in the middle of the compartment. Battery and radio as shown in the instructions. Barbie was the pilot. [u]Balance[/u]: Plane balanced without any adjustments a little forward of the recommended c.g. range (done upside down), but flew nicely. I was having a difficult time with landings. They were "heavy" to say the least even broke a wheel hub and lost the tire on one. Eventually considered that I was running out of elevator (on low rate), so re-balanced the plane right at 3-1/8" on the mean cord line from LE. Required 1 oz lead right over tail wheel. Plane flew fine, but was light on the controls. Club instructor and one of the best pilots agreed, so removed 1/2 oz. Plane now flies great and my landings are much improved. I have plenty of elevator on low rates. I have used only 1 gal of fuel so far, so I consider myself still a newbie. [u]Question[/u]: [u]Has anyone modified the gear to allow more give?[/u] A tack weld on the cross wire popped on one of my heavy landings. I cut the remaining welds, added fuel tubing around it, then tied that to the cross brace with brass straps. That added a little give, but I was wondering about other approaches. Love the airplane. John
Posted on: 10/14/2009 1:03 PM by Author "jpanhalt"
in the forum "ARF or RTF"
http://www.rcuniverse.com/forum/fb.asp?m=9172178
RE: crop duster r/c
Hi Jeff248, I am down here in Cleveland, Ohio and have a Pawnee 40. I am also designing a 1/4 scale version from measurements I took of a couple of full-size versions nearby. I do not have the Piper drawings, but will try to insert a gif file of a CAD drawing I made. We probably need to correspond off-line to exchange CAD files. [image]http://www.rcuniverse.com/forum/uploadpro.asp?memori=&deletefile=Wu61764.gif&mode=&messageid=[/image] I too would like to modify the Pawnee 40 gear to have a little give. Currently, I brazed a 5/32 doubler to the forward cross member. I brazed only the outer ends (about 1/4"). Then for the cross brace, I attached it with slings made from brass sheet and used fuel tubing to provide a little give. It is very strong and doesn't bend, even with the hardest landing, but it still doesn't have a lot of give. I am thinking of increasing the amount of rubber, but doing that will put a lot of stress on the 5/32 main forward rod. Any other ideas? John
Posted on: 9/27/2009 12:32 PM by Author "jpanhalt"
in the forum "RC Scale Aircraft"
http://www.rcuniverse.com/forum/fb.asp?m=9127370
RE: New CDI - opensource project JMJ and Bigboat
[quote]ORIGINAL:boating around The advance curve for a 2 stroke is opposite to that of a 4 stroke. A 4 stroke will advance as rpm rise, a 2 stroke retards as rpm rise.[/quote] You refer to experts and your own work. How about giving some reference citations, particularly for your claim that the advance curves are opposite for 4-stroke and 2-stroke engines, that can be checked. Can you provide the schematic and pictures of the PCB for your redesigned and working ignition? John
Posted on: 8/6/2009 11:06 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8994310
RE: New CDI - opensource project JMJ and Bigboat
[quote]Original:boating around Unziping to folder and opening with programming software sounds easier and should work??? [/quote] Just how do you have any idea what is easier for me to do to get a quick look at a hex file? Did you know that I keep MPLab and other important software on a separate computer from the one I use to answer e-mails, surf the Internet, and participate in forums? That computer wasn't turned on at the time. Doing as I did will tell someone what is in the hex file. If it is corrupted, it will appear that way. It is just not going to invert two of the hex digits and leave the rest untouched. [quote]Original:boating around edit: I hope people have been reading what bigboat has been saying. [/quote] I have been from the start of this thread. We all owe thanks to Bigboat for providing the information originally and for the gracious help he has provided to anyone and everyone who has come along. I have never seen him not help a sincere person who was trying to make this DIY CDI work. He is not getting paid for his efforts. I just reviewed the Hall sensor connections, and they look OK to me. Bigboat doesn't need any defense, but I would like to take this opportunity to thank him in this theater of criticism you are trying to create. There's an American saying, "Pioneers take all the arrows." I am sure Bigboat will understand what that means. John
Posted on: 8/6/2009 11:03 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8898562
RE: New CDI - opensource project JMJ and Bigboat
[quote]First line of your hex differs slightly to mine, why??? Hope you have written it correctly.[/quote] I just un-zipped the hex file, changed the extension to .txt, opened in notepad, copied and pasted. Formatting into nice columns is lost that way, but the meat of the code should not be affected. I didn't bother firing up MPLab to look at it in any more detail. John
Posted on: 6/30/2009 7:23 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8894022
RE: New CDI - opensource project JMJ and Bigboat
A year or so ago, I built the HV side only based on the schematic, and it worked. On the bench, I used a simple oscillator to trigger the device. As for the parts list/schematic discrepancies, I could not find the parts list to which you refer. Note that 100n is the same as 0.1 uF, so at least C5 and C7 are should not be on that list. The hex.zip file with the original post un-zips to give for the first line : 00008B29FF3FFF3FFF3FEE300313831286052E I have no idea whether that is correct, as I was not interested in the MCU part. Good luck, John
Posted on: 6/30/2009 5:47 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8893905
RE: Understanding wife....
Why are you playing with airplanes? [:D] John
Posted on: 5/5/2009 7:34 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8743791
RE: gas glow in a supertigre 40
Methyl hydrate is probably methanol aka methy alcohol. That interpretation is based on the context and chemistry. Another possibility is a clathrate of methane and water, which is found in deep oceans and wells. Basically, that is a crystalline form of methane (which is normally a gas) that forms under pressure with water. It is relatively stable and has been considered as a way to transport methane easily. Methane hydrate (not methyl hydrate) is a more appropriate name for the clathrate. As for the carcinogenicity of burning acetone, think of all the other things that are being burned in our engines, such as nitromethane, methanol, oil, and various additives to the oil. All of those things produce active chemical species when burned and should not be enhaled continuously. Just don't run them in a closed room. Even toasting bread produces carcinogens. John
Posted on: 4/3/2009 7:19 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8646052
RE: Opensource CDI ignition
Re:C3 An SCR gate will stay open until the current through the SCR drops below the holding current. Since that is not a GTO SCR, once fired, there is no control of the open time, except for that discharge period. Most datasheets for SCRs will give the firing criteria, which is generally something like a pulse with a minimum duration, voltage, and dA/dt (i.e., Vgt and Igt). The BT151 is characterized at a dI/dt of 5A/uS, which gives a turn-on time of 2 uS. I didn't study the datasheet that carefully, and there may be more data, but I did not see a minimum or maximum dI/dt for the gate. Consider a 0.1 uF capacitor with an esr of 100 ohm. The time constant for that alone is 10 uS. Using another capacitor with an esr of 10 ohm, which gives a minimum time constant of 1 uS should not affect the gate opening. The point here is not to criticize or to redesign the circuit, but to find available components that can be substituted and will work. Even in the USA, I am not about to buy the minimum quantity of 0.1 uF aluminum electrolytic capacitors from DigiKey. John
Posted on: 3/28/2009 8:46 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8625010
RE: Opensource CDI ignition
Sorry about that. I interpreted that discussion to be about availability, not necessity for using electrolytics. C3 is used for firing the SCR. I reverse engineered two commercial CDIs (a Chinese import and an RC Ignitions from the USA). Both used mylar/polyester. On the bench, I have used ceramic as well for that function. I can't see that a high esr would be any advantage in that application. C7 is for the oscillator. The reverse engineered units used aluminum electrolytics, but they used much higher values of 1 or 10 uF. ESR might make a difference, but I am not so sure a lower ESR would be bad. A common, small tantalum at 0.1 uF would have an ESR of about 10 ohm (not low esr version), which is comparable to the esr of the larger electrolytics. Nichicon didn't list the esr of the 0.1 uF in the datasheet I had. By comparison to others, it probably has an esr of at least 10 ohm or as high as 100 ohm. That is just a rough calculation based on the inverse relationship of esr and capacitance given the same tan delta. John
Posted on: 3/28/2009 6:11 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8624835
RE: Opensource CDI ignition
I don't understand why you need the electrolytic capacitor at that location in the circuit. Why not use a ceramic? If you need more ESR, add a resistor. John
Posted on: 3/27/2009 7:30 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8623109
RE: Rhino Lithium Batteries
I wish I could report on experience with the battery. Based on the advertising and almost reasonable shipping, I ordered 2, 2200 mAH, 3S Rhino packs. My PayPal was charged immediately. More than a week later, still not shipped. Customer service said it would be shipped "today". Next day, still not shipped. Customer service said may be shipped in a few days. No refund, no money. The on-line status report seems to be, shall we say, inaccurate. Processing can mean backordered with indefinite ship date. In my experience with Rhino (HobbyKing/Hobby City), the suspense and poor service is not woth the savings. John
Posted on: 3/10/2009 5:19 AM by Author "jpanhalt"
in the forum "E-Flight Power Sources"
http://www.rcuniverse.com/forum/fb.asp?m=8562234
RE: Source for good knurling tool?
Try the national tool chains, like MSC, J&L (now MSC), and Rutland. There may even be some Boeing surplus dealers where you are. As a last hope, try McMaster-Carr. It has a wide selection of things, including knurling tools, but within a specific item class, the choices are more limited than with a specialized tooling supplier. One thing you will have to consider is the size of your tool holder. A lot of knurling tools are too big, unless you have something like and Aloris or Dorian quick change. John
Posted on: 2/24/2009 4:31 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8513748
RE: Opensource CDI ignition
Happymcc, If you are unable or unsure of how to program the PIC chip, there is lots of help available. Many electronics hobbyists will be able to do it for you. Almost certainly, high schools and local colleges also have the ability. It should cost nothing and takes almost no time to do, once you have the code in electronic format. Check around. If you strike out, I would be happy to do it for you using the "standard" code. John
Posted on: 1/12/2009 5:34 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8348523
RE: Opensource CDI ignition
Actually, I was going in the direction of the FLPS with a Coilcraft transformer. I recently got the FL2015-9L, but have not had time to experiment with it. I think Martin's approach with voltage feedback is also worth looking at. At least, we have a long Winter ahead of us in which to test our ideas. John
Posted on: 11/12/2008 12:31 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8140119
RE: Opensource CDI ignition
Martin, I appreciate the update. I had the same goal of a CDI with commercial transformer, but got onto another project 6 or 8 months ago. That project is nearing completion, so I may get back back to the CDI. Please keep us updated on what you find. The components you chose certainly look promising. John
Posted on: 11/12/2008 9:35 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8139606
RE: Opensource CDI ignition
Futterama, Do you know if the 100 ohm resistor in Vcc is necessary (presumably it helps stabilize power to the controller)? If needed, what is the smallest wattage resistor you been able to use? The LT3750 and Coilcraft DA2032 look pretty good, or are you using the larger DA2033/2034? John
Posted on: 11/12/2008 8:23 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8139465
RE: Bolt Tapping?
Got you now. I thought you were talking about safety wiring it. Shouldn't be much of a problem for a gunsmith or anyone with a lathe. John
Posted on: 10/25/2008 10:28 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8083217
RE: Bolt Tapping?
Drilled-head cap screws, both socket and hex head, are pretty common and probably would be a lot cheaper than paying someone to do it. What are your specific screw specifications (diameter, length, material, finish, head style, thread style, head diameter, thread length)? John
Posted on: 10/25/2008 10:04 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=8083165
RE: Opensource CDI ignition
I can't read your schematic. The lousy JPG resolution makes reading any part identifiers almost impossible. On Bigboat's site, T1 is an ignition coil. Q1 is the thyristor. As for why it is a thyristor, I suspect the high pulse-current capability, easy gate control circuit, and easy turn off contribute to the reason. John
Posted on: 6/30/2008 7:10 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=7679360
RE: professional home build ignition new update
It's not CDI and runs off 12 V. Could probably use a 3S pack for it. John
Posted on: 1/30/2008 9:03 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6998830
RE: Milling Machines for engine Conversions
[quote]ORIGINAL: tim220225 Actually you need one of these to run a single phase motor. https://www.anaconsystems.com/text/eagle1.html [/quote] Been there with a KB drive for a single-phase motor. I would not recommend it. Do you want to make an offer on my old drive that is barely used (i.e, just used it to find out it wouldn't work)? They are finicky. At the slowest speeds, I had to give the shaft a twist to get it to go with no external load. And as mentioned in my earlier post, there are different drives for different types of single-phase motors. Do you know what type yours is from an electronic standpoint? The small additional cost of a cheap 3-Ph motor and controller with all of the advantages they bring is well worth it for a tool you may have for 20 years or more. John
Posted on: 1/13/2008 4:41 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6901192
RE: Milling Machines for engine Conversions
The beauty of the VFDs for 3 phase is that they come in two types. Those that run off 3-phase, and those that run off single phase. Since you do not have 3-phase, you want to get the single-phase type. Again, there are two choices. Some run off 220 volt and others run off 110V. Both produce 3-phase at 220V. I think it is the latter type that you probably want, unless you have 220V in your shop. John
Posted on: 1/12/2008 11:38 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6898134
RE: Milling Machines for engine Conversions
Something like a VFD is made for single phase, but you have to know exactly what type of motor you have. That is, the starting and running configuration and some other things about the way the coils are connected. I got one awhile back from KB drives. It worked, but only sorta. Most important, you will loose low-speed torque. The motor may also make strange noises. In contrast, I have a VFD and 1/2 HP [edit] 3-phase motor on my drill press and it is absolutely quiet. As Tim220225 said, you can slow it down to a walk and still have plenty of torque. My advice, get a used 3-phase or new one (about $100 or even less on the aution site) and use a conventional VFD. If yo only have 110V, then I think the options are a cheap converter to give you 220 single phase, or get a DC motor and DC controller. John
Posted on: 1/12/2008 10:28 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6897006
RE: $25 CDI
Sure! The last thing I bought and had sent International Mail (via USPS) was from England. Shipping cost was $100, and it still hasn't arrived after almost 1 year. USPS is hopeless in tacking or follow-up. I was told flatly that it could not be tracked until it reached my local P.O., even though it has a GB tracking number. It may be a good deal, if you get it. In the future, I won't buy anything international, unless it is shipped by a carrier, such as FedEx, DHL,etc. The difference is in the way such shipments clear Customs. I was told by the USPS that USPS items go through item by item (if it goes through at all). The other carriers clear a whole container at a time. It's much harder to mislay one of them. John
Posted on: 1/7/2008 6:53 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6870419
RE: Lathe for conversions
It's hard to say whether it would work. You would need to confirm the correct width of the ways. Center height could be adjusted as long as it is not lower or a lot higher than yours. You would need to be sure the gear on the new unit would mesh with the rack gear under the ways for back and forth movement, and the the half-nuts would have to match the lead screw in position, size, and pitch. There is a good chance the pitch is the same, but the lead screw diameter and position might be different. The positon and diameter would have to match with a pretty close tolerance. I am not sure exactly how close they have to be. My gut tells me a few thousanths and certainly lesss than 0.015. If the rest of your carriage is in good shape, I would just replace the broken gear. Is there a Vo-Tech or high school (that still has metal shop) near you? They might help with the machining. It is really not much to do. If not, I would put the carriage approximately where it belongs and set the compound at 90°. With that set-up, you would have the cross slide to work as usual and the compund would act as if you had a funtional carriage for making the part. Travel won't be much, but you don't need much for boring the gear and turning the shoulder. Use drill stock for the shaft and you will be set. Drill stock can be bought with a ground finish in almost any size from industrial supply places. It doesn't matter which type you get (oil, water, or air hardening). I usually just use oil hardening. I would also call some used machinery dealers, if they are near you. They often have parts salvaged from machines and might have a gear that would fit. Their price, of course, will be negotiable. John
Posted on: 1/5/2008 5:34 PM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6859204
RE: Lathe for conversions
Here is a part from an Atlas 618/Craftsman 101.214 lathe:http://cgi.ebay.com/Atlas-618-Craftsman-101-metal-lathe-Cross-Slide-Assy_W0QQitemZ190186985347QQcmdZViewItem?hash=item190186985347 Since some of these sites block links, the auction number is: 190186985347 Failing that, can the shaft be pressed from the handle? I assume so, there may be a tapered or dowel pin holding it. I would get a spur gear, bore it to slightly smaller than the shaft. Make a new shaft with appropriate shoulder, and press it on. You may need to pin it axially or tack weld it. If you try to cross pin it, you run a greater risk of messing up the gear teeth, but it is still doable. A pinion gear (not certain of the term), that is a gear on a extended shaft like you have, may also be available. It does not look like a particularly hard repair. They are just plain, not helical gears. If you need help looking up the part, give dimensions and tooth count and I can help. Assume everything is inch measurement. John Edit: Just looked at the link more closely. I don't think that part will fit afterall. But, I would keep looking for auction pieces. The biggest problem is that some of these lathes are now collector items, and the prices go skyhigh. Saw an old Unimat go for well over $1000.
Posted on: 1/5/2008 7:27 AM by Author "jpanhalt"
in the forum "Engine Conversions"
http://www.rcuniverse.com/forum/fb.asp?m=6856769
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