Aloha Mike and Insighters: I've been lurking on various Insight sites seekingn background data that could be relevant to powering a homebuilt aircraft (which I already have-a flying boat) with an insight motor/IMA. Most aircraft
require twice as much power for take off as they require in cruise flight.
Obviously the MIMA is a step in the right direction, if it could be "overboosted" to say 20KW for 10-20 seconds. Flying power settings are much more steady-state than in autos, starting at 100% for take off (20 seconds), then 75-85% for climb (<5 minutes) and finally 65% or below for cruise. The MIMA or a similar manual control device could make this feasible.
The Insight engine is about the lightest one litre engine around, with the Suzuki 3 cyl. Metro engine a close second. The new sport pilot regs are going to encourage the design and construction of two seater aircraft weighing <1300 lbs. It may even be possible to use the Insight without a speed reduction unit for the propeller, but the bearings required to isolate gyroscopic forces from the crankshaft may be just as heavy as a reduction drive.
I apologize in advance for my lack of technical Insight comprehension, but
the MIMA discussion caught my attention. I would like to eliminate the fuel injection (carburators are reliable and good for constant power settings), install a magento (reliable) and eliminate all of the black boxes if possible. If not possible, then at least simplify the circuits/boxes to save weight. Can the Insight IMA ever be simplified to this point? Please direct me to any past posts that might help. Mahalo and Aloha. David
The biggest problem I foresee is a battery recal where all IMA assist is lost. The complexities of aircraft engines, or should I say simplicities make such a conversion a serious engineering challenge. The Insight is much more complex and potentially much less reliable, nor suitable for use in all orientations. Oil starvation at angles "X" (?) beyond vertical is the first the comes to mind.
Since this is essentially a different topic from the MIMA project I am splitting this into its own topic. There are a few other Insight / aircraft pilots (private pilot myself) that may also reply to your post.
Dumbing down the Insight engine for use in an aircraft would not make sense. The high efficiency of the engine depends on the very things you would want to remove for "reliability". Furthermore, in a calculation of the power to weight of an Insight engine, you must consider the weight of all the IMA batteries and support electronics.
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Kip Munro
The laws of physics don't need changing, but rather our attitude and values. 72.8 LMPG
I've had occasional late-night thoughts about using the Insight engine in a small homebuilt - like I'd ever have the time to really do it - but always concluded that 1) the weight of batteries &c would outweigh the gains; and 2) the hidden charging would kill your cruise.
With MIMA objection #2 would go away, so it might be doable, even possibly practical. If it were me, though, I'd re-think changing the electronic & fuel injection, as that's what gives the engine a lot of its efficiency. Reliablity doesn't seem to be an issue. I have a Piper Cherokee, and over maybe 10 years & 1500 hours have had 2 or 3 carb problems (one requiring replacement), and had to install new mags due to an AD. Have had zero problems in 2 years / 20K miles of Insight driving, and don't recall seeing much of anything related in the problems section.
What I would do, though, is look seriously at the turbo kit. Not just for power gains, but to keep the power at altitude. And maybe you could get lean burn in cruise
To supply 20kW additional for 10 minutes (take off and climb plus a bit of reserve) would require a bigger assist motor (the existing motor is 10kW). 20kW for 10 minutes also adds up to 3.3 kWh, which is quite a lot of battery energy storage, at least 5 Insight battery packs would be required to provide that at 80% DOD which, including the casings and electronics, would add up to about 5 x 35 = 175 kg.
It might be worth checking out AC-Propulsion, who are quite advanced in the whole electric aircraft thing. They use 220 Wh/kg Lithium-Ion cells which are about one fifth the weight of the same amount of energy storage in Insight style NiMH, and obviously when it comes to aircraft, weight is everything. A 3.3kWh pack of these could therefore weigh in at only 15kg (3300/220), though electronics and casings would add substantially to this.
Aloha Hana hou: The Insight technology and its possible application to aircraft was first proposed by no less than Burt Rutan himself, when asked to review the Insight by Road and Track (Rutan's EV-1 had been reppoed by GM the day prior to the interview.
Q by R & T:
"Does he see any application of hybrid propulsion for airplanes? An innocent question, although it leaves Rutan unusually silent. "Gee, maybe I shouldn't disclose this in Road & Track. But at the risk of someone else doing this first, let me tell you about an airplane that would be really interesting to do. This is fascinating...."
Rutan leans back and stares into middle distance. "Visualize an electric airplane with enough batteries to climb to about 500 feet. Actually, it would have several small electric motors with small propellers scattered all around the airplane—some on the tail, some on the wings—so if one motor seized, it's just a nuisance. Plus, there's a phenomenal advantage here: You wouldn't need control surfaces. Put a motor on a high part,one on a low part and give the first power and the other negative thrust or regen, and you pitch down, for instance.No elevator, no ailerons, no rudder. "Okay. Now after climbing to 500 or 600 feet, the batteries are pretty much puked. However, onboard would be this gas-powered generator that would produce 10 to 20 percent more [electrical] power than you need to cruise. The climb from 500 feet would be slow, but, the most important part to climbing is the initial part, getting over the trees.
For landing, or even if something bad happens like the generator seizes or you run out of gas, all the way down the props would be doing regen,charging the batteries up for a controlled landing (altitude being equivalent to potential energy). During the last part coming down, you actually want drag anyway; a very efficient airplane needs flaps or speed brakes to slow it down. "Here's a prediction: You may find that within the next few years Burt Rutan will go off and build one of
these."
I assume Rutan was thinking more of a RPV or UCV, but the concept makes sense but without Lipoly batteries and their fire issues. Gold Peak and other Nimh cells are now capable of 100 amp discharge rates without dropping below one volt at 68 grams apiece. An aircraft would require only brief power bursts, not power density. High tech electric motors for models are reaching 4KW at 2kg. weight again only for 30 second bursts. Rutan's idea of eliminating flight controls is interesting, but is probably designed to simpify the control system computer design.
Getting back to the Insight and flying, most successful aircraft conversons from auto engines have been engines which were run on their limits while in cars, for a high percentage of power duty cycle. Two examples are the VW and the Suzuki (metro); both cars require a substantial fraction of the max avaiable power to run on the street. The Insight is the same, and is designed with this high power fraction in mind. Yes, it has complicated valve gear, fuel injection/ignition mapping, idle-taming software, etc., but it's basically an engine that runs nearly flat out at Interstate speeds, particularly when no IMA power is available.
there are other reasons on flying boats to have a substantial amount of electric power generation or electric boost (not to mention engine starting) would be very handy. Every time I get on my Yamaha Waverider (1200cc) and accelerate to 50+ I think how a flying boat could get off the water instantly if it had an electric-powered jet pump or pumps rather than an air propeller (usually cavitating) during its take off run. More importantly, takintg Rutan a step further, bury the ICE in the hull and power all the propellers electrically. The loss of efficiency in the ICE-to-electrical conversion and re-conversion back to propeller rotation is more than compensted for by the increase in propeller efficiency with multiple propellers (not in the water spray), lighter weight, lower G.G. (no ICE motor high on a pylon). Some of the ICE power could be mechanically transferred to a pylon mounted propeller.
My same questions remain about the ability to boost IMA power for short periods; is this possible, and can the multiple control systems be reduced in complexity or hard-wired to reduce risk off single-point failures? More later and mahalo to this who replied. David.
is this possible, and can the multiple control systems be reduced in complexity or hard-wired to reduce risk off single-point failures? More later and mahalo to this who replied. David.
Really short answer: no.
Slightly longer answer: Yes, but you would need to simulate all the sensor inputs with a computer (microcontroller), or make a totally new ECM that ignores these inputs.
There are several failure mods that will turn off the IMA system, and these failure modes are common (O2/LAF sensors, for example). This would be bad in an aircraft.
It sounds like the safest way to do this might be to just use the Insight gasoline engine and remove all the IMA components. Then you would just have the lightweight 124 lb. engine without all of the IMA control boxes and battery pack, and you would not have to worry about the IMA system failing. Of course, that would only work if the engine could supply enough power to take off. The gasoline engine alone has 67 hp @ 5700 rpm, and more if you turbocharged it. The IMA motor does not add much horsepower, mostly just torque. If my understanding of that is correct (it may not be), it may not make much difference on a propeller once it is up to speed.
This would still be a difficult project with many other things to consider, for example, you might need to add an alternator or a large battery supply to keep the engine running without the IMA system and its 12V DC-DC converter.
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- but always concluded that 1) the weight of batteries &c would outweigh the gains; and 2) the hidden charging would kill your cruise.
