As If Efi Issues Aren't Hard Enough!
06-15-2004, 04:49 PM
#21
Senior Member
Join Date: Nov 2003
Location: Hell (Colorado School of Mines)
Posts: 521
Why not just let each EFI run independently? You would have to find room for 2 ECUs, but they aren't that big or heavy. Also, you would have to splice a throttle cable to both throttles, but as long as that is adjusted right, I don't see why it wouldn't work. Uh.. on a sidenote, you really should use 2 TBs, if you aren't already planning on it. They are enough of a restriction for one engine, I cant imagine how bad they would be if you tried to double the amount of air going through them.
06-15-2004, 08:05 PM
#24
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Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
How much length do you have to work with? 2 13B's linked together with a coupling will be around 30" long. Are you going to have room for that as well as enough radiator to cool it, and the turbos, IC, etc?
The engine is doable, and making a coupling isnt really that hard. I could design you a nice 2 piece one in about 20 min. Treat it as 2 seperate engines, and its as straight forward as a 2 rotor, just have to do everything twice.
But the part that makes you come across as a delusional mental case is that you want to design your own 500 hp airplane. Are you a pilot already? Im guessing not.
The engine is doable, and making a coupling isnt really that hard. I could design you a nice 2 piece one in about 20 min. Treat it as 2 seperate engines, and its as straight forward as a 2 rotor, just have to do everything twice.
But the part that makes you come across as a delusional mental case is that you want to design your own 500 hp airplane. Are you a pilot already? Im guessing not.
06-15-2004, 09:33 PM
#25
to infinity & beyond, me
Join Date: Aug 2001
Location: santurce
Posts: 5,124
34 acres????? can i get one?
umm, yeah, 2 engines one propeller, correct. id research and see how much info is out there about scoots 4 rotor FD. also, i see how u want 500 hp, id approach first what would be the easiest/reliablelest way to get 250 out of 1 engine. then make a copy.
umm, yeah, 2 engines one propeller, correct. id research and see how much info is out there about scoots 4 rotor FD. also, i see how u want 500 hp, id approach first what would be the easiest/reliablelest way to get 250 out of 1 engine. then make a copy.
06-15-2004, 09:48 PM
#26
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Join Date: Jun 2004
Posts: 36
You tell me, CG? Can I run both independently? If so, problem solved since I can most certainly put in a linked throttle cable system that is very precise. The space and room for the ECU's would be in the nose since I need permanent counterweight up there anyway, & two TB's were the plan all along since considering this engine config.
Colin, CG, the issue is not power exclusively....it's more about safety and redundancy. That's why I decided on rotaries to begin with; they almost never catastrophically fail giving me a chance to bring the ship to earth safely. V-8's and such have a nasty habit of throwing rods, breaking cam/crankshafts, cracking blocks, ect. which almost always requires a complete engine shutdown in any aircrafts flight manual emergency procedures. There have been numerous cases of inflight rotaries blowing their seals whereby the pilots reported still having about twenty-five percent power and the engine continued to "turn & burn" until safely back on the hard-deck. Having one rotary engine is good, having two is outstanding! The power is a benny.
MS7, I have plenty of room in my ship for the engines & their accessories so long as I keep everything in a tandem config. I have spent over 1,000 hours designing my ship using flight models & over 100 hours flight testing her in the X-Plane simulator, which is the only sim that the FAA recognizes as a legit real-world flight program. The aircraft actually only needs about 250HP@5252RPM to be a success, but I'm one for safety, and when it comes to flying safely, there is almost never a situation of too much power! I currently have three flight models, one of which is this version with corrected weight/balance, CG, fuel load, and power levels. And I appreciate your offer to make a coupler, but that is well within my skills....it's the electronics where I could use help. And as with most experimental aircraft builders, the building of their bird coincides with the gaining of their license....that is the case with me. As to the "delusional mental case" I may be all that and more(God knows my wife thinks so!) In my twelve years with the Marines I did many things like a 3,500ft free-jump out of a perfectly good Navy airplane, rescueing people from a burning boat in shark-infested waters, and was even known to do stupid things like stand mere feet from the engine-test afterburners of an F-4 Phantom to warm my hands in Iceland. Crazy? Yea, I'm crazy.....but now, in my older age, I actually think before I jump. By the way, you want your knife back? FLOL!!!!
Colin, CG, the issue is not power exclusively....it's more about safety and redundancy. That's why I decided on rotaries to begin with; they almost never catastrophically fail giving me a chance to bring the ship to earth safely. V-8's and such have a nasty habit of throwing rods, breaking cam/crankshafts, cracking blocks, ect. which almost always requires a complete engine shutdown in any aircrafts flight manual emergency procedures. There have been numerous cases of inflight rotaries blowing their seals whereby the pilots reported still having about twenty-five percent power and the engine continued to "turn & burn" until safely back on the hard-deck. Having one rotary engine is good, having two is outstanding! The power is a benny.
MS7, I have plenty of room in my ship for the engines & their accessories so long as I keep everything in a tandem config. I have spent over 1,000 hours designing my ship using flight models & over 100 hours flight testing her in the X-Plane simulator, which is the only sim that the FAA recognizes as a legit real-world flight program. The aircraft actually only needs about 250HP@5252RPM to be a success, but I'm one for safety, and when it comes to flying safely, there is almost never a situation of too much power! I currently have three flight models, one of which is this version with corrected weight/balance, CG, fuel load, and power levels. And I appreciate your offer to make a coupler, but that is well within my skills....it's the electronics where I could use help. And as with most experimental aircraft builders, the building of their bird coincides with the gaining of their license....that is the case with me. As to the "delusional mental case" I may be all that and more(God knows my wife thinks so!) In my twelve years with the Marines I did many things like a 3,500ft free-jump out of a perfectly good Navy airplane, rescueing people from a burning boat in shark-infested waters, and was even known to do stupid things like stand mere feet from the engine-test afterburners of an F-4 Phantom to warm my hands in Iceland. Crazy? Yea, I'm crazy.....but now, in my older age, I actually think before I jump. By the way, you want your knife back? FLOL!!!!
06-15-2004, 10:41 PM
#27
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Join Date: Sep 2002
Location: Savannah, Ga
Posts: 2,763
Well I apologize for my assumptions. Ive seen one after another pipe dreams from people who dont even know enough to understand what theyre wanting to do.
First off, the engine. you want 500 reliable HP. My recommendation is to scrap the whole turbo idea. Run an aviation sized PP. 250 hp per 13B is easily attainable at around 7000 rpm. Run a 2.83:1 reduction drive, and the prop speeds are ideal. The coupler is quite easy, and I actually designed one before realizing a 30" long engine wont fit in damn near anything short of a viper or another large car. A 2 piece coupler can be made to sidestep the end play adjustment for the rear 13B. As you may or may not know, the end play of the ecc shaft is set by a spacer, and eventually the front hub. Make one piece of the adapter mimic the stock hub in how it attaches to the ecc shaft of the rear engine and a flamge coming forward to match up with the front piece of the coupling that will be bolted to the rear counterweight of the front engine. You could possibly even make the coupling bolt directly to the counterweight. Then an adapter to go form the back of the front engine to the front of the rear engine. Use the bellhousing bolt holes on the front engine, and the front cover bolt holes in the rear engine. The front cover bolts are strong enough, because the 12A's have the engine mount bolted to the front cover. Just leave an opening to be able to bolt the coupling together.
You have 2 options for ignition. Make a provision on the adapter between the engines to run a distributor there as well as the front cover. If you want redundancy, bolt the engines together so the #1 and #3 rotors fire at the same time(which will make #2 and #4 also fire at the same time) and set up the distributors so each distributor fires one plug for each rotor.
For fuel, you have a few options, but theyre all simple. You can run carbs, and be done with it. Or you can run fuel injection. Go ahead and scrap the idea of usign the stock ECU. You do NOT want to use the stock ecu. Its a piece of ****. http://www.rotaryaviation.com/ There is a lot of good stuff on that site, including an aviation specific EMS for rotaries.
Can you put up a rendering of the plane you designed? Im seriously interested, since you messing with two things very close to my heart. Im an aircraft mechanic and soon to be pilot as well, and rotaries are nothing short of an obsession.
And lastly, good luck, and Ill be of as much help as I can.
First off, the engine. you want 500 reliable HP. My recommendation is to scrap the whole turbo idea. Run an aviation sized PP. 250 hp per 13B is easily attainable at around 7000 rpm. Run a 2.83:1 reduction drive, and the prop speeds are ideal. The coupler is quite easy, and I actually designed one before realizing a 30" long engine wont fit in damn near anything short of a viper or another large car. A 2 piece coupler can be made to sidestep the end play adjustment for the rear 13B. As you may or may not know, the end play of the ecc shaft is set by a spacer, and eventually the front hub. Make one piece of the adapter mimic the stock hub in how it attaches to the ecc shaft of the rear engine and a flamge coming forward to match up with the front piece of the coupling that will be bolted to the rear counterweight of the front engine. You could possibly even make the coupling bolt directly to the counterweight. Then an adapter to go form the back of the front engine to the front of the rear engine. Use the bellhousing bolt holes on the front engine, and the front cover bolt holes in the rear engine. The front cover bolts are strong enough, because the 12A's have the engine mount bolted to the front cover. Just leave an opening to be able to bolt the coupling together.
You have 2 options for ignition. Make a provision on the adapter between the engines to run a distributor there as well as the front cover. If you want redundancy, bolt the engines together so the #1 and #3 rotors fire at the same time(which will make #2 and #4 also fire at the same time) and set up the distributors so each distributor fires one plug for each rotor.
For fuel, you have a few options, but theyre all simple. You can run carbs, and be done with it. Or you can run fuel injection. Go ahead and scrap the idea of usign the stock ECU. You do NOT want to use the stock ecu. Its a piece of ****. http://www.rotaryaviation.com/ There is a lot of good stuff on that site, including an aviation specific EMS for rotaries.
Can you put up a rendering of the plane you designed? Im seriously interested, since you messing with two things very close to my heart. Im an aircraft mechanic and soon to be pilot as well, and rotaries are nothing short of an obsession.
And lastly, good luck, and Ill be of as much help as I can.
06-16-2004, 10:56 AM
#28
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Thread Starter
Join Date: Jun 2004
Posts: 36
Yea....I've looked hard at the PP setup.......the thing for me is the drop-off in torque at the RPM's required for the PP to make the 250HP. Even after Tracy's 2.85:1 PSRU, the torque is not what I expected considering all the work to mod the engines into peripherals, right? Or am I missing something?! I mean it's not like I can just take these TII's and bolt up the PP system......it takes quite a bit of internal working to prep a 13B for that kind of setup, not to mention pulling double-duty to get two engines ready(now I'm preachin' to the choir...FLOL!) I was trying to get a local shop to step up & give me some deep discounts on the work to do a PP job on my engine, and in turn, I would publicize his shop religiously, but he wasn't interested. This bird is going to be the first of it's kind, highly identifiable, and interviewed in a number of magazines worldwide once she's up and running. Tracy Crook is the one who got me stoked on rotaries, but he says his controllers won't work for dual, linked engines. I do really like your version of the coupler, though, as it would certainly do the trick. Do you have X-Plane? If so, I can mail you the zipped version of my bird, and you can help yourself to flying her about......I gotta warn you, she don't fly like no C172(I pretty much fall asleep landing the 172 now!)........more like a hyper Cessna Citation....FLOL! I just got my 150MPH custom triple-caliper brakes and wheels from Matco, and I'm getting ready to install them onto the main gear strut, so I may not be back online today.......depends on how easily they mount up to the strut. After that, I've got to rerun the cost numbers for these different setups vs reliability........it may swing back around to a single engine, I just don't know yet....but I will. See ya! 
06-16-2004, 12:42 PM
#29
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Join Date: Jun 2004
Posts: 36
Ya'll ever notice that sometimes you'll get what you think is a handle on a problem only to have MURPHY throw you a serious curve????? Well, that's just what happened to my twin engine concept. Lo and behold, the engines'/accessories spacing is not an issue, but the retracted tandem landing gear going into the same space is!!!! While in X-Plane I noticed that the tandem engines would have to have a stubby prop-shaft between them in order to give room to the tandem 5" tires to be fully retracted within the fuselage.......damn those details......FLOL!
It looks as if I'm back to trying to figure out how to make a single 13B make the power........a powerful PP & the 2.85:1 PSRU or just a ballsy 13B turbo and the standard 2:1 PSRU?!
It looks as if I'm back to trying to figure out how to make a single 13B make the power........a powerful PP & the 2.85:1 PSRU or just a ballsy 13B turbo and the standard 2:1 PSRU?!
06-16-2004, 01:01 PM
#30
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Join Date: Jun 2004
Posts: 36
DANG!!!! I just went out to the ship's fuselage and did some quick measurements to see how tight the fit would be, and while it can be done with a 6" prop-shaft between both engines, it puts the forward engine too close to the fuel supply for my liking. It's too bad. Having the second engine at that location would make CG issues a lot more manageable.......maybe a no-**** firewall there in addition to the one forward of the fuel? HHhhhmmmmm. But then no cross-fuselage spar-bracing for the wings......hhhhmmmmmmmmm.