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SuperTigre 4500 conversion
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OK Deezel buds, I found a sort of suitable muffler for the 4500, its probably going to be loud even for a Diesel but at least I can run it. Should I pressure tap it, I dunno. I tried to mount the really uglyful J-Tec, but someone had enlarged the holes and the bolt spacing is a little wide also. I should get a chance to run it tomorrow.
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RE: SuperTigre 4500 conversion
Oh baby, I sure would like to see that one run Hobbs ;)[8D]
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RE: SuperTigre 4500 conversion
Nice dave maybe you can use a 10 or 15 as a pony engine to start it ( had to say that) Just lucked out in the other direction (smaller) got an Irvine 20 diesel for $53 on flea bay, guy has a good rating used but stated to be in great shape said a few cosmetic scratchs on back plate (plastic) he fitted a spring under the tommy bar guess he lost the grub screw to lock it . I have a spare screw so will use it and leave my NIB irvine 20 in the box for now and use this one martin Dave I would drill and tap for pressure fitting if you do not need it just use a small cap screw to seal it off |
RE: SuperTigre 4500 conversion
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This is the plane I want to put it on an AMR Trainer 50. What do you think. It would have a Biss on Pitts muffler and be side mounted.
Wingspan : 104” Fuse length : 80” Wing area: 2080 Sq. inches Flying weight: 24 pounds Stab length: 35 inches Stab area : 420 Sq. inches Plug-in wing |
RE: SuperTigre 4500 conversion
I ran mine without pressure and had a sT60 Carb for my conversion It is a suprisingly quiet running engine as you reall can load it up to the size props that you might use an a 4.2 gas. A 24.8 was in the high 5's to 6K and the idle was under 1k. It is cold blooded so give it time to warm up or you will probably end up over compresses, i used a Su;;ivan Dynatron to start mine but i never ran it as a glow so it was a long time getting run in. The companion Quadra 50 conversion had a sportster 65 carb and turned the same rpm as the ST.
Dennis |
RE: SuperTigre 4500 conversion
I keep meaning to get a diesel head for my G4500 too. I just haven't done it yet.
A 24 inch prop size sounds like a pretty good fit for the engine too. The diesel engines seem to run more quietly than a glow or gasoline engine does. I think it is the way the fuel is burned more completely inside the engine before it is let out. Thus the mufflers can be smaller with less volume to them. I like your plane choice, it looks pretty good to me. |
RE: SuperTigre 4500 conversion
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It runs, I used a Sullivan Dynatron as Dennis did, it started on about the 3rd compression stroke, as Dennis also said, it's cold natured although it required a full turn of compression from where it started so it may not be so cold natured next time. I managed to get the J-Tec muffler on it by grinding a couple of washers flat on two side, you can see one of them. It definitely needs a larger prop, I had to bury the compression screw to get 6,650. Boy is it smooth, acceleration is nearly instant even with the heavy Classic 20x10. Well, now all I need is $375 bucks for the plane, 50 bucks for a Just Engines Jen-C/Biela 21x12 prop and 54 bucks for a bisson Pitts muffler. Nothing to it, beyond a small miracle.
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RE: SuperTigre 4500 conversion
Hobbsy its loafing really needs that bigger prop and of course compression screw will then be able to be raised, biga bucks for this airframe thats why i stick with the smaller ones, like boats, a forty footer 4 or 5 times the price of the 20 ft one martin
But you only live once |
RE: SuperTigre 4500 conversion
Your Bhp is over 6.6 and yor thrust is over 39 lbs with a flight speed projection of 63 mph +. Not to shabby.
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RE: SuperTigre 4500 conversion
WELL...THAT SAYS IT ALL, GASSERS ( WHY)//?? MARTIN
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RE: SuperTigre 4500 conversion
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Thanks Bob and Martin, Bob that banged up piston worked well just like you said it would. I used one of your miniture file sets to straighten up the ring groove. SuperTigre 4500s have big guts. I've had new piston back ordered for 2 years now. I gues I'll cancel it.
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RE: SuperTigre 4500 conversion
ORIGINAL: ddd Your Bhp is over 6.6 and yor thrust is over 39 lbs with a flight speed projection of 63 mph +. Not to shabby. A 20x10 prop at 6650 RPM is around 3HP. :eek: Check your figures. Greg |
RE: SuperTigre 4500 conversion
According to Pe's calculator, 6.6 is right one the money. The prop and rpm make me happy and will fly the plane I have very well.
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RE: SuperTigre 4500 conversion
Dave, I have no doubt it will fly a model just fine. It's plenty of power. I just checked Pe's calculator, I don't normally use it, and it also gives ~3.3HP. To put this in perspective, there are a few posts that put the DLE 30 over 7k on a 20x10, and it's rated 3.7HP at something near 9k. What exactly are you putting in?
I'm just being accurate. Doubling power by going to diesel is great, when it actually happens. |
RE: SuperTigre 4500 conversion
I followed Pe's example and put in a 20x10@6,650 the same as he put in a 20x8@7,000, I got 6.6, his example got 7.02.
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RE: SuperTigre 4500 conversion
That's incorrect. What prop constant are you using? From another perspective, if a 45cc engine is making 6.6HP at 6650, BMEP is 143psi. That would be positively stunning. At 3.3HP the BMEP is a realistic 77psi.
Try this site I found. http://personal.osi.hu/fuzesisz/strc_eng/index.htm Greg |
RE: SuperTigre 4500 conversion
That chart is only useable if your goal is to make some good engine look bad. I like my engines to look good.
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RE: SuperTigre 4500 conversion
Well Supertigre's instructions, brochures and stuff recommend a 22x8 or 22x10 prop for a glow engine. Thus a prop around the size of a 24x8 or 24x10 prop for the diesel sounds about right to me. I think the 20x10 prop would be too small on the engine. if you have to screw in the contrapiston almost all the way that would also imply that the prop is too small too.
But yeah buying a nice assortment of extra large props gets expensive real fast too. |
RE: SuperTigre 4500 conversion
Thanks Earl, I pretty much new before I started it yesterday that the 20x10 was too small but I wanted to run it. I'd like to have another Classic but they don't make one larger than the 20x10. The 21x12 Just Engines Jen-C which is a rebadged Biela is 54 bucks and the 21x10 three blade is 97 bucks. Of well.
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RE: SuperTigre 4500 conversion
Dave, how many prop power calculators have your tried? I'm certain the spread sheet I've been using for 15 years is accurate. I tried several other calculators after you were so adamant, but the math is simple and even with pen and paper I get the same result. One last try on my part. Download Pe's latest version of his site and browse through the other pages, you'll find a prop curve for Xoar props, that puts the 20x10 at about the same as I say, and engine testing of the MVVS 80cc turning a 24x10 at 6630 making a little over 7HP.
Dave, I know you think I have some vendetta against diesel, I'm just an engine fanatic, and I know incorrect figures when I see them. I have many figures saved from those I deem credible to get an idea of what engines are capable of. Every one of these is backed up by calculating the BMEP, which double checks the figures for sanity. it's not rocket science, and BMEP or torque calculations always blow the lies out of the water, in any engine discussion. Once again, tell me these are wrong. I have a 30cc in my CMP Spitfire. I have used 20X10 Zinger 6800rpm (way to big) I am really surprised at the power of the DLE 30. with a Menz Ultra 20x10 wood prop at 7140 rpm, 90.6db; If the ST4500 is so strong why does a 30cc gas outperform it? I've invited Pe to have a look at our figures. Greg |
RE: SuperTigre 4500 conversion
You are correct I thought it was a 24X10 rather then a 20X10.
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RE: SuperTigre 4500 conversion
ORIGINAL: Hobbsy Thanks Bob and Martin, Bob that banged up piston worked well just like you said it would. I used one of your miniture file sets to straighten up the ring groove. SuperTigre 4500s have big guts. I've had new piston back ordered for 2 years now. I gues I'll cancel it. |
RE: SuperTigre 4500 conversion
ORIGINAL: gkamysz Dave, how many prop power calculators have your tried? I'm certain the spread sheet I've been using for 15 years is accurate. I tried several other calculators after you were so adamant, but the math is simple and even with pen and paper I get the same result. One last try on my part. Download Pe's latest version of his site and browse through the other pages, you'll find a prop curve for Xoar props, that puts the 20x10 at about the same as I say, and engine testing of the MVVS 80cc turning a 24x10 at 6630 making a little over 7HP. Dave, I know you think I have some vendetta against diesel, I'm just an engine fanatic, and I know incorrect figures when I see them. I have many figures saved from those I deem credible to get an idea of what engines are capable of. Every one of these is backed up by calculating the BMEP, which double checks the figures for sanity. it's not rocket science, and BMEP or torque calculations always blow the lies out of the water, in any engine discussion. Once again, tell me these are wrong. I have a 30cc in my CMP Spitfire. I have used 20X10 Zinger 6800rpm (way to big) I am really surprised at the power of the DLE 30. with a Menz Ultra 20x10 wood prop at 7140 rpm, 90.6db; If the ST4500 is so strong why does a 30cc gas outperform it? I've invited Pe to have a look at our figures. Greg |
RE: SuperTigre 4500 conversion
I said nothing about anything other than the quoted power figures. The 21x12 would be a good choice. I guess it would turn 6100-6200 RPM. That would allow you to throttle back to get a reasonable cruise speed and burn less fuel. Less pitch would be slow and you might find yourself flying at high throttle to keep it moving. That AMR Trainer 50 is sure to be a floater, but it depends if you like to fly slowly or not. Unfortunately, trying several props if you don't already have them is an expensive proposition.
Besides, what does it matter what the head looks like when it's buried under a cowl? I'm waiting on a Graupner Taxi 2400. I hope everything fits under the cowl. The engine has to be built before I worry about that much. Diesel or not, it's going to be four stroke. |
RE: SuperTigre 4500 conversion
ORIGINAL: earlwb The diesel engines seem to run more quietly than a glow or gasoline engine does. I think it is the way the fuel is burned more completely inside the engine before it is let out. Thus the mufflers can be smaller with less volume to them. This is why diesels can get away with such small external expansion chambers for mufflers, their internal thick walled 'expansion' chamber compliments it well. |
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