Register

If this is your first visit, please click the Sign Up now button to begin the process of creating your account so you can begin posting on our forums! The Sign Up process will only take up about a minute of two of your time.

Page 1 of 7 123 ... LastLast
Results 1 to 25 of 162

Thread: 1/2 A Fuel


  1. #1

    Join Date
    Oct 2002
    Location
    Fremont, NE
    Posts
    465
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    1/2 A Fuel

    Where can I find 1/2 A fuel with more than 15% nitro? Most people recommended 25% or more but the only fuel I can find in that range is labeled as "Heli Fuel". Will this work? What would be the ideal portions of nitro and castor oil for 1/2 A? What do you use as the base to blend this concoction? Any recommendations would be greatly appreciated.
    Steve Westphal

  2. #2
    combatpigg's Avatar
    Join Date
    Nov 2003
    Location
    arlington, WA
    Posts
    17,667
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    You might need more than 15% nitro to improve the idle, but you might not need the idle as low as you might think.
    Sounds like "wishy-washy advice..?
    I've got a worn out TD .049 that does over 100 mph on 12-15% nitro fuel.
    Bumping it up to 30% nitro will not DOUBLE the speed, but it will come close to doubling the cost of the fuel.
    I've run Cox engines on 0% nitro and even though you can easily see a drop off in performance, I still had more than enough power to fly a RC combat plane in a typical combat-like pattern.
    If you need more nitro, go to the source. Seek out the advice of your local drag racers and find out where they buy it. I've been able to buy 5 gallon cans of it for very reasonable prices.
    The last can I bought has lasted me about 4 or 5 years.
    If you mix your own fuel entirely from scratch, you will spend way more on oil than you will on methanol and nitro.
    The most powerful engine I have is a piped .40 that is designed to run on 0% nitro.
    WHO GUNNA FEED MAW KEEEIDS..???

  3. #3
    vicman's Avatar
    Join Date
    Dec 2002
    Location
    Valdese, NC
    Posts
    9,818
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    I'm a pretty simple guy. I buy 25% car fuel and add a good dollop of castor. My stuff is pretty fast too
    A guy who used to live on this site and now is rarely here due to the "upgrade".
    Most likely fading away till the My Forums is fixed. Too bad.

  4. #4

    Join Date
    Jul 2005
    Location
    Upper HuttWellington, NEW ZEALAND
    Posts
    1,358
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Don't Sig still do fuel in a variety of nitro %s?-I'm pretty sure they used to do a castor based 35% nitro blend ideal for 1/2As. And unless you're going for some very exotic event (eg 1/2A C/L speed) you shouldn't need more nitro than that. Heli fuel should be OK-providing the lubricant % is adequate. If you're talking about Coxes then it would pay to have some castor (at least 5%) in the fuel-simply to give the highly stressed ball and socket little end a bit of protection. Your alternative is to buy R/C car fuel and up the oil content to a safe level, [do a search here-there have been several threads mentioning this and how to do it] or blend your own mix-but you may well find that blending your own isn't any cheaper, simply due to the component quantities you'd be purchasing.

    Note what CP says above-doubling the nitro won't double the power or speed-but will significantly increase your fuel costs. The idea should be to use as low a nitro as you can get away with, not as high a level as you can get away with. [I know there's a few people out there using 65% in 1/4A-1/2A engines-but they're usually FFers like me-and only have to worry about short runs.........and idling is not a consideration!]

    ChrisM
    'ffkiwi'

  5. #5
    skaliwag's Avatar
    Join Date
    Jan 2003
    Location
    santa cruz, CA
    Posts
    2,362
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    There is a SIG fuel for every one. My choice.
    Attached Thumbnails Attached Thumbnails Click image for larger version. 

Name:	Ay73596.jpg 
Views:	16 
Size:	295.3 KB 
ID:	1817989  
    Real Airplanes have Round Engines and Two Wings.

  6. #6
    rcguy59's Avatar
    Join Date
    Jul 2008
    Location
    tacoma, WA
    Posts
    972
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    I use Wildcat 30% Heli fuel spiked with 6 oz. Sig castor per gallon. My Norvels love it and I get two seasons out of a gallon, including giving some away.
    Jet Central Superbee & Rabbit
    18MZ FASSTest for everything I fly

  7. #7
    Max_Power's Avatar
    Join Date
    May 2005
    Location
    Savage, MN
    Posts
    566
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Having a lot of different engines that want different fuels I have begun mixing my own lately, And with great results!

    I buy a gallon of Nitro from TORCO on ebay ($50.45 shipped to my door) Sig has either straight castor ($22) or klotz techniplate(39)(I LIKE this stuff!, been mixing in a small percentage to even my 1/2a stuff to find a nice balance of clean/protected) a gallon plus $10 shipping for a gallon or two. I take down two jerry cans and buy 10 gallons of methanol from a local oil supplier for $2.25 a gallon. The only other thing needed is a squirt of armorall per gallon on high castor blends to keep foam down, and a drop or two of glycol food coloring if you want to help you identify mixes. You have to spend a few bucks to get started, but after that its nice being able to mix as much or little of what you want, not have to keep 6 different whole gallon blends around, You can mix up small batches to experiment, etc.

    In all honesty I think this stuff even runs a bit better than the store bought (I know-prolly in my mind) I've been running this in my cars, 4-strokes, 1/2a, and normal medium 2 strokes for a year or so now. I even use the techniplate to mix fuel for my Gas heli. If you can find a local buddy to help split shipping for oil and gas for the drive to get methanol it can be even cheaper!...I just like having the ability to have whatever spec fuel I want even if I just want a pint mixed in 5 minutes. Plus at even the high nitro stuff maxxing out at about 24$/gal (35 nitro 20% castor oil) and the cheaper stuff (5%nitro, 18% oil) being as cheap as 9$ Gal plus fuel to the LHS saved at some point the investment pays off even more. In my opinion as long as you burn 2-3 gallons a year combined with all your models, or can do that between you and a close friend or two it is well worth it...Plus it brings another source of Hobby fun and pride[8D] Straight methanol at $2.25 a gallon is also the cheapest post flight or engine cleaner I have come by. Todd
    \"A guy told me the other day I must be very smart,......I told him \"No!, I\'\'m REALLY dumb, But learning from my mistakes!!\"\"

  8. #8

    Join Date
    Feb 2007
    Location
    , MI
    Posts
    1,765
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel


    ORIGINAL: Steve Westphal

    Where can I find 1/2 A fuel with more than 15% nitro? Most people recommended 25% or more but the only fuel I can find in that range is labeled as ''Heli Fuel''. Will this work? What would be the ideal portions of nitro and castor oil for 1/2 A? What do you use as the base to blend this concoction? Any recommendations would be greatly appreciated.
    I've heard good reports on Glow Plug Boy fuels. They seem like they specialize in 1/2A fuels and the bottles are sized that way to avoid HAZMAT fees.

    Pricing is pretty fair too.

  9. #9
    Mr Cox's Avatar
    Join Date
    Jul 2007
    Location
    Karlstad, SWEDEN
    Posts
    3,109
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Which engines are we talking about here?
    I can't think of any engine I have that "needs" 25% nitro.

    On the contrary there are many engines that are setup for 0-10% nitro. Adding more nitro without changing the compression ratio will not give any improvements, especially on sport sized props.

  10. #10

    Join Date
    Jul 2005
    Location
    Upper HuttWellington, NEW ZEALAND
    Posts
    1,358
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel


    ORIGINAL: Mr Cox



    On the contrary there are many engines that are setup for 0-10% nitro.


    Adding more nitro without changing the compression ratio will not give any improvements, especially on sport sized props.

    How many 1/2A engines do you have that run well on 0% nitro Mr Cox?

    Actually your comment about adding more nitro and compression ratio is a bit of an over generalisation-it assumes the compression ratio was right in the first place! If the engine was undercompressed to start with, then adding more nitro WILL show an improvement-until you reach a point where the engine is effectively overcompressed for the fuel you're using-THEN its appropriate to decompress with shims or head gaskets depending on the engine construction.

    ChrisM
    'ffkiwi'

  11. #11
    Mr Cox's Avatar
    Join Date
    Jul 2007
    Location
    Karlstad, SWEDEN
    Posts
    3,109
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Well that's why I'm asking which engines we are talking about that would need 25% nitro?

    Here are a few examples where I have personal experience. For running on 5.7-6x3 props;

    Brodak MkI (CS); the two I have were overcompressed even on 0% nitro. It needed 3-4 head shims to run on 10% nitro.
    AP wasp; runs fine on 0% nitro, can handle 10% but I don't think it needs any more nitro.
    Cox 05 RC; overcompressed for 10% nitro with the TD head and one head shim.
    MP Jet; comes with three head shims installed and seem fine for 10%nitro, I haven't tried higher
    Cox engines with the Merlin head; needs about 3-4 head shims to run on 10% nitro (I haven't tried it on 0%)

    Larger engines;
    HB .12; set-up for 0% nitro, needs headshims to run with more nitro
    MDS .18; set-up for 0% nitro, needs headshims to run with more nitro

  12. #12
    GallopingGhostler's Avatar
    Join Date
    Oct 2004
    Location
    Clovis, NM
    Posts
    1,186
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Steve Westphal: Where can I find 1/2 A fuel with more than 15% nitro? Most people recommended 25% or more but the only fuel I can find in that range is labeled as ''Heli Fuel''. Will this work?
    I recently bought 30% O'Donnell Heli Fuel from Tower Hobbies, 2 quart bottles. It was cheaper than the 1 pint 1/2-A fuel. It states it has non-petroleum lubricant, which I believe is Castor oil. After discussion in the RCGroups.com forum, I received feedback it should work, so I bought. To really make them sing, these half-A's love nitro.



    If you are really deeply and conservatively concerned, Sig Manufacturing is selling their Champion 25% for eight bucks per quart. Half the oil content is Castor oil. I've used their fuel for my half-A's and it works fine.http://www.sigmfg.com/cgi-bin/dpsmar...FV5.html?E+Sig



    Nonetheless, I'm excited with the Heli fuel, its flying time! [8D]

    Post Note 20-Nov-2012 - Per the O'Donnell website, http://www.odonnellracing.com/airplanefuel/index.html the 30% nitro Heli Fuel is all synthetic without Castor oil content. It is general consensus that the Cox engines with their piston ball and socket joint for the connecting rod should use a fuel containing Castor oil. This is to ensure that there is adequate lubrication to the joint, as Castor oil has a higher temperature tolerance than synthetic oils. Castor oil burns off 100 degrees higher than the synthetics.
    George Hostler
    Clovis MADS AMA Club, Vintage R/C Society (VRCS)
    And we know love by this, that He laid down His life for us, and we ought to lay down our lives for the brethren. 1 John 3:16

  13. #13
    Mr Cox's Avatar
    Join Date
    Jul 2007
    Location
    Karlstad, SWEDEN
    Posts
    3,109
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    What engines will you use this fuel in?

  14. #14

    Join Date
    Feb 2003
    Location
    Murray, KY
    Posts
    3,099
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    I have been using Morgan's Sidewinder Pro 30/10 and 20/10, blending the two together and adding castor oil to get the nitro/oil ratio that I want.
    the "other" andrew
    I'm not older than dirt, but I can remember when it was patent pending

  15. #15

    Join Date
    Jul 2005
    Location
    Upper HuttWellington, NEW ZEALAND
    Posts
    1,358
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel


    ORIGINAL: Mr Cox

    Well that's why I'm asking which engines we are talking about that would need 25% nitro?

    Here are a few examples where I have personal experience. For running on 5.7-6x3 props;

    Brodak MkI (CS); the two I have were overcompressed even on 0% nitro. It needed 3-4 head shims to run on 10% nitro.
    AP wasp; runs fine on 0% nitro, can handle 10% but I don't think it needs any more nitro.
    Cox 05 RC; overcompressed for 10% nitro with the TD head and one head shim.
    MP Jet; comes with three head shims installed and seem fine for 10%nitro, I haven't tried higher
    Cox engines with the Merlin head; needs about 3-4 head shims to run on 10% nitro (I haven't tried it on 0%)

    Larger engines;
    HB .12; set-up for 0% nitro, needs headshims to run with more nitro
    MDS .18; set-up for 0% nitro, needs headshims to run with more nitro
    Well I wouldn't consider .12 and .18 engines to be 1/2A to start with-and this thread is about fuels for 1/2A.

    Can we establish what you consider to be 'over-compressed'? For me (and I'll restrict myself to 1/2A pertinent comments-as on larger engines there is usually a plug eating component associated with over-compression) it is when an engine becomes balky to start-snappy, backfiring, sometimes kicking the prop off, and hard to needle on a particular fuel. There are 2 options for curing this-either drop the nitro, or raise the head clearance with either shims or gaskets. [in reality there is a third-changing the load-but this is often not a practical option]
    Conversely 'under compressed' for me is when the revs drop noticeably as soon as you disconnect the glowplug lead-and is what I invariably find with Cox 049 reed valves if operated on straight fuel or a 5% mix [now this is also indicative of too cool a plug-but with a Cox you don't have the option of varying the plug heat-but you can swap the TD head for the low compression reed valve head and vice versa] FWIW there have been two aftermarket attempts at Cox heads with different heats-one Canadian and one from Lion Electronics in Australia but neither survived in production. Note that I'm not considering aftermarket heads just at this point-the heads I'm referring to were clones of Cox heads with a different heat range.

    My Brodak Mk1 was/is a gutless wonder on typical 1/2A fuel, and I managed to get a custom Nelson head for it. Overcompression was definitely not an issue. Virtually all my Russian 049s (and I have quite a few) are undercompressed as supplied (some embarrassingly so)-and now sport either Cox heads or Galbreath Nelson ones. I don't have any running data on Norvels yet-though I have several NIB 049 and 061s
    The only 1/2A engine where I've encountered over-compression on a significant number of occasions would be the TD 049/051-and that's on 30% nitro and 5-1/4x3 props. Solved either by more gaskets-or my preferred method is fitting the lower compression #325 head -which in my experience quickly tames a balky TD!
    I've run 40% in my MP Jets without any indication of overcompression-but I'm propping for 26,000 rpm in an F1J FF application...........

    ChrisM
    'ffkiwi'

  16. #16
    hllywdb's Avatar
    Join Date
    Apr 2009
    Location
    Vero Beach, FL
    Posts
    952
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    I'm with skaliwag on this one. I run Sig 25% (all castor) in most of my 1/2A engines. I run 35% on a few I want a bit more performance from (with corrected compression) especially in the heat of summer here in FL. I have been happy with the Sig fuels for 20 yrs.

  17. #17
    GallopingGhostler's Avatar
    Join Date
    Oct 2004
    Location
    Clovis, NM
    Posts
    1,186
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Mr Cox: What engines will you use this fuel in?
    Mostly reed valves, but also Norvel .061 ceramic, .09 and .10 Schneurles and Baffle Pistons. I live at 4,300 feet elevation, so a little more umph! in the fuel helps.

    But I know what you mean. I used to run 10% - 15% K&B (100) and Duke Fox fuel in .049 reed valves and McCoy's, .020 Pee Wee, .10 OS Max Baffle Piston R/C, etc., and they did okay at sea level. (Remember Missile Mist?) This was when the hotter Cox or K&B 1000 fuel wasn't available. This was non-competitive sport flying, chewing holes in the sky, paddling like a one legged duck in CL.
    George Hostler
    Clovis MADS AMA Club, Vintage R/C Society (VRCS)
    And we know love by this, that He laid down His life for us, and we ought to lay down our lives for the brethren. 1 John 3:16

  18. #18
    GallopingGhostler's Avatar
    Join Date
    Oct 2004
    Location
    Clovis, NM
    Posts
    1,186
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    hllywdb: I'm with skaliwag on this one. I run Sig 25% (all castor) in most of my 1/2A engines. I run 35% on a few I want a bit more performance from (with corrected compression) especially in the heat of summer here in FL. I have been happy with the Sig fuels for 20 yrs.
    Sig makes good fuel, no doubts about that.
    George Hostler
    Clovis MADS AMA Club, Vintage R/C Society (VRCS)
    And we know love by this, that He laid down His life for us, and we ought to lay down our lives for the brethren. 1 John 3:16

  19. #19
    rcguy59's Avatar
    Join Date
    Jul 2008
    Location
    tacoma, WA
    Posts
    972
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    I bought some of the O'Donnell heli fuel from Tower a couple of years ago. My Norvel .074's liked it so much, I've run heli fuel ever since. I still spike it with additional castor, though.
    Jet Central Superbee & Rabbit
    18MZ FASSTest for everything I fly

  20. #20
    combatpigg's Avatar
    Join Date
    Nov 2003
    Location
    arlington, WA
    Posts
    17,667
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Don't forget that when it comes to Nitro Philosophy that decreeasing the load will allow the engine to get maximum benefit from a nitro boost just as well as lowering static compression.
    The two go hand and hand as tuning tools.
    If you get greedy with either the load OR the compression you will end up running your engine like the Top Fuel guys who change pistons and rods every round.

    BTW, COX .049s run fantastic with 5x3 props on 40% nitro and just 1 shim. That's mostly all I ran for the years that I flew 1/2A C/L Combat. If the engine couldn't turn 23,500 then it didn't get to make the trip to the next contest.....but that isn't a practical "cocktail" for sport flying. It consumes glow plugs every other run.
    WHO GUNNA FEED MAW KEEEIDS..???

  21. #21
    GallopingGhostler's Avatar
    Join Date
    Oct 2004
    Location
    Clovis, NM
    Posts
    1,186
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    combatpigg: [A lot of good initial advice snipped] BTW, COX .049s run fantastic with 5x3 props on 40% nitro and just 1 shim. That's mostly all I ran for the years that I flew 1/2A C/L Combat. If the engine couldn't turn 23,500 then it didn't get to make the trip to the next contest.....but that isn't a practical ''cocktail'' for sport flying. It consumes glow plugs every other run.
    Good advice, combatpigg. 40% is a little aggressive for what I do. On the 25% Sig Champ fuel, I was getting decent plug life. At sea level, I was using 5x3's, 5-1/4x4's, 6x3's, etc.

    One thing I learned about flying at elevation, like Gallup, New Mexico (6,500 feet or 1 981 m), in this case R/C, the effects of props were more dramatic. The .049 Black Widow on a light weight Airtronics Q-Tee with decent wing area would barely poke along with a 5-1/4x4 prop. This same prop at sea level had about the same performance speed wise as a 6x3 prop. Changed to a 6x3 prop, the plane hauled decently.

    CLARIFICATION 19-Nov-2012. The following recommendations came about from further research. As usual, YMMV (your mileage may vary):

    I have found that the 18% oil content in O'Donnell 30% Heli Fuel is synthetic. Unless otherwise recommended by the engine manufacturer, this fuel should be okay for those who have Schneurle ABC or ABN engines, as long as one tweaks the needle to ensure the engine does not run lean and as long as the engine does not run in a hot condition (avoid oversized props, ensure adequate cooling around the engine, etc.)

    Those who have engines with iron/steel pistons or piston rings in a steel cylinder liner or ball and socket connecting rod to piston joints in small engines such as Cox should use a fuel containing Castor oil. Only Castor continues to lubricate 100 degrees above where the Synthetic oils burn off. Those with early well worn legacy engines should use 100% Castor oil, to prevent erosion of the built up film caused by the detergents in Synthetic oils, allowing the engine to maintain its compression seal.
    George Hostler
    Clovis MADS AMA Club, Vintage R/C Society (VRCS)
    And we know love by this, that He laid down His life for us, and we ought to lay down our lives for the brethren. 1 John 3:16

  22. #22

    Join Date
    Jul 2005
    Location
    , TN
    Posts
    253
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    Just a little historical correction. The nitro content in K&B fuels was as follows K&B 100 was 5%, K&B 500
    was 12 1/2%, and K&B 1000 was 25%.

  23. #23
    Mr Cox's Avatar
    Join Date
    Jul 2007
    Location
    Karlstad, SWEDEN
    Posts
    3,109
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel


    ORIGINAL: ffkiwi

    Can we establish what you consider to be 'over-compressed'? For me (and I'll restrict myself to 1/2A pertinent comments-as on larger engines there is usually a plug eating component associated with over-compression) it is when an engine becomes balky to start-snappy, backfiring, sometimes kicking the prop off, and hard to needle on a particular fuel. There are 2 options for curing this-either drop the nitro, or raise the head clearance with either shims or gaskets. [in reality there is a third-changing the load-but this is often not a practical option]
    With over compressed I mean a tendency to overheat, a touchy needle setting, and you get a small gain in rpm (100-300rpm) when/if you lower the compression by adding a head shim. Changing the prop to a lower load will also help and resembles the addition of a head shim.

    I'm not questioning people who are doing F1J, they certainly know their stuff, and I don't think they would ask for fuel advice on this site.

    What I'm reacting to are comments like "1/2a engine love nitro", that's is an old rumor, and very common around here too. Perhaps it started with cox readies on their low compression heads. I think this is partly responsible for the decline in running small engines here. One of the most common questions I get is along the line "How much nitro do you have to use in that?"

    If this thread is about high nitro in cox sure-starts engines, on the low compression head, then I apologize for the intrusion. Just make sure there is at least some castor in that heli fuel.

  24. #24

    Join Date
    Jul 2005
    Location
    Upper HuttWellington, NEW ZEALAND
    Posts
    1,358
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    The most potent fuel I ever brewed was 50% nitro-and at that percentage, the fuel has a tendency to separate if castor is used (to be really accurate-from 45% nitro onwards the fuel has difficulty in staying homogeneous)-unless you add additional components. Fortunately acetone at a few % will keep things stable. I only ever used this fuel in 049/051s in FF Payload-where you were lugging a big heavy model (16oz) with compulsory ROG on a 15 sec engine run and still trying for a 3 min max. That fuel was noticeably more powerful than my standard 30% nitro 1/2A contest mix-but it cost me two pistons holed through the top over the years......
    The TD range was developed around the Cox racing fuel-which was 30% nitro content, and a castor base. I think the exact makeup has been published somewhere on the net-perhaps on the Martin Hepperle site. Bear in mind that as a competition oriented FFer, I only have two engine throttle settings-flat out and stopped on 1/2A engines! I still prefer a properly sorted and well setup TD [mine are all carefully blueprinted] to any of the 'cheap' Russian engines for competition use. Of course the seriously expensive Cyclon, Fora and Profi 049s/061s are a different issue. For sport use (and I have to admit I'm not a great fan of the Cox reed valves) I generally use the British stuff-DC Bantam, DC Wasp, Frog Venom or the Fox and K&B front rotary 049s-and these I run 10-15% nitro.

    Whilst digging through my archives earlier today I found some of the original Norvel technical notes, where they recommended an upper limit of 35% nitro for Norvel engines.

    So I guess-and generalising(your mileage may vary!), my recommendation across the board would be 10% nitro as a minimum starting point, and 35% as a practical maximum, with 10-15% for general sport use, and 25-35% for competition. Unless you're seriously flying 1/2A pylon or doing a speed model, it would be hard to justify the 25-35% fuels for general R/C use from a cost point of view. [from a FF perspective-fuel costs are almost irrelevant-when you're talking 7 sec or 10 second engine runs-I would use less fuel in a day's flying than a 1/2A RC flier would in one flight, assuming a typical 1-ounce or 2 ounce tank in the RC model]

    ChrisM
    'ffkiwi'

  25. #25

    Join Date
    Jul 2005
    Location
    Upper HuttWellington, NEW ZEALAND
    Posts
    1,358
    Gallery
    My Gallery
    Models
    My Models
    Ratings
    My Feedback

    RE: 1/2 A Fuel

    [quote]ORIGINAL: Mr Cox



    With over compressed I mean a tendency to overheat, a touchy needle setting, and you get a small gain in rpm (100-300rpm) when/if you lower the compression by adding a head shim. Changing the prop to a lower load will also help and resembles the addition of a head shim.
    [quote]

    OK Mr Cox-you and I are in general agreement on our respective definitions of 'overcompressed'-though our respective experiences with various brands and model of 1/2A engine seem poles apart. This could reflect no more than the observation that I am running very light loads almost exclusively. I did mention reducing the load as a possible solution-but also noted that this may not be practical in a lot of cases, as the model may fly better on a larger prop. Its no big secret that over propping a glow engine usually results in overheating-even though the engine runs slowly.......

    I will accept there is considerable truth though in the premise that smaller engines 'need' nitro as opposed to 'love' nitro. This is certainly supported by the smaller Coxes (010 and 020) being a lot happier on the higher nitro blends than the lower.

    One of the big names-perhaps George Aldrich, Joe Klause or Henry Nelson-(I don't recall now) wrote a good article quite a few years back (70's?) which among other things mentioned the unfavourable surface area to volume ratio of the very small engines which means that they lose heat faster than bigger displacements, and this is why they respond well to the additional heat liberated by nitro containing fuels. Conversely-at the other end of the scale, the bigger engines suffer from the opposite problem-difficulty in dissipating the heat generated while running.

    ChrisM
    'ffkiwi'


Page 1 of 7 123 ... LastLast

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •  
All times are GMT -6. The time now is 07:58 PM.

SEO by vBSEO 3.6.1 ©2011, Crawlability, Inc.