That plane is really, really pretty.
Your product is really, really, impressive too. I believe I met you at oshkosh. I like what you're doing.
That plane is really, really pretty.
There are two things that bother my eye: the fuselage extension changes from constantly changing rate of change to a "straight taper" in the plug. The second is strangely the paint job: those three "chevrons" behind the cabin I find a bit offesnsive. The latter easily corrected.I know that the original 2 seater was a very attractive aircraft. However, the fuselage extension done on this aircraft is also a very attractive modification. You need to see it in person, it looks like a bullet.
Being one of the founding year members of the AYA, I promise you I DO remember who designed the BD-1 (but in all fairness, NOT the AA-1). To say that butchering one of the greatest little airplanes of all time is offensive to me is an understatement, but I was pointing out who's engines were included in this heinous offense on one's senses.You are talking about 2 different families of airplanes.
John Thorp designed his T-18 homebuilt plus the Fletcher/Cresco/PAC 750XL series that is still built in New Zealand. John Thorp also designed the first Derringer before production was taken over by George Wing.
The Grumman-American series of light singles is based upon the BD-1 light 2-seater designed by Jim Bede. Under GAA management, they developed some 4-seater variants. I have a few hours flying a GAA Cheetah and rather enjoyed it.
This light twin is based upon a GAA single.
Why this example (N134GB) has the word "Derringer" on its engine nacelle is a mystery to me.
EPI is IMHO not authorative. They have all the answers yet no marketable designs.Read this and this and this very carefully. I'm a big fan of LSs for aircraft use but a pilot should give some very sober consideration to all of the potential failure modes and ask himself if he'd like to double those odds of something going wrong. This is not a level of complexity that many homebuilders want to mess with. Three times the power of an O-360 (540-600hp) is decidedly in forced-induction racing territory (i.e. higher than Sweet Dreams' normally-aspirated SBC) unless one is willing to sacrifice reliability for higher mean piston speed.
The cost of a car motor is maybe 25% of a certificated one. The cost is not a significant factor.The number one thing experimental builders complain about are engine prices. Now we are going to have to purchase 2? Hard pass.
All the aviation insurance web sites state that insurance is required,yet none have shown a FAR or state law.When I dug into this a few years ago, there is a "moving" liability insurance requirement in almost every state; especially if the airport gets any state funds.
Surprising what you can do with a lighten straight tail C-172 with one notch of flaps at 60 mph.Wing Derringers biggest problem is they are slow. They should be a rocket but they aren’t. Cool for sure. Cockpit is small.
Aircams are a blast. They fly like any floaty plane of its type. Cost is pretty rough. Most cool kids would probably go for a Backcountry Cub in that price bracket. Aircam’s biggest problem is it’s not certified. It’s a plane that needs a job. 80% helicopter in an airplane. Photographs, aerial surveys, wildlife counting. I could put one to work right away.
Really. All converted for aircraft use and everything? So why don't we see way more of them flying?The cost of a car motor is maybe 25% of a certificated one. The cost is not a significant factor.
Think about how the larger single-rotor helicopters (EH-101 Cormorant and Sikorsky CH-53 Stallion) have three jet engines connected to single transmission and the connection is through Sprage clutches, so if any single engine quits, they only lose 33 percent power and the quiet engine does not drag on the transmission.For series built planes:
Velocity V Twin
For one offs:
Twin Engine Quickie 1
RV6a Built as a Twin
To directly answer your question, you don't see a lot of twins for a whole slew of reasons. Most practical, is due to common design practices, you end up with lots of interference drag, and despite having some large multiple of the a single engine's horsepower, you typically don't see a whole lot more performance. One big engine generally works out better.
Your suggesting that they aren't overly complicated is .. well lets talk about that. Sure, you can build a powerplant, and supporting systems, and then do it twice. Good! That's the easy side. Once one engine goes out, a whole lot of things can go very wrong. This is compounded with the idea that most twins are setup as planes designed to be fast, so there's a lot of compromises to the flying qualities of the plane, so you get the higher performance.
When things go wrong in a twin, they go "a lot more wrong". Lets say you manage to get it into a spin. Your plane has engines way out at the ends of the airframe, giving you a large polar moment of inertia. If your spin develops at all, you're not fighting a pair barbell with 300lbs on each end, that's 20' long. While if you're flying a cherokee or something, nearly all your mass is near the center. High performance twins also tend to have small control surfaces so they behave well in their designed operating speeds.... Which makes their surfaces pretty marginal in an emergency.
It's possible to design a twin that has no VMC, but you quickly lose performance. There are some planes that are like that. They're not fast...
Twins also typically have constant speed props. This means it can be really tricky to determine if there's a problem.
There's a whole lot of other factors that make figuring out a POH for your experimental that makes it a very complex issue. It's also likely you don't have good enough test pilot to get that entirely sorted out. And if they DO find a problem, are you a good enough engineer to sort it out?
Single engines just don't have any of those issues.
I've been thinking about this sort of thing for a year or two now. Sadly those industrial v twin's don't have great power to weight. Why stop at two though? With two, when one dies, you have 1/2 your horsepower gone, and some significant drag. If you have four... an engine out would only be 25%.
I also pondered some sprag clutches and driving the same prop... Completely nonsense, but it was fun to consider.
Seems like a good way to disconnect an engine when failed. One-way freewheeling clutches are found on single or multi-engine helos... location for single engine usually on the trans; for multi-engine, varies with whether there is an intermediate trans like an engine nose-box or c-box. On the 212/412, clutch integrated into the combining gearbox of the PT-6 TwinPac. Biggest issue with clutches is hard engagement from over-running...that can be a noisy and expensive problem. Def one of the checks we did on second engine start was to make sure the clutch engaged as N2 came up, and then disengaged with spool-off of other engine.Think about how the larger single-rotor helicopters (EH-101 Cormorant and Sikorsky CH-53 Stallion) have three jet engines connected to single transmission and the connection is through Sprage clutches, so if any single engine quits, they only lose 33 percent power and the quiet engine does not drag on the transmission.
Airplane crashes are expensive and painful, but nothing compared to the agony personal injury lawyers can inflict on anyone vaguely related to the crash.It's certainly possible to get something with decent range, payload, handling, ergonomics, and - yes - looks in a small 2-4 place twin, as the Diamond DA-62 shows, but the cost to tool up for what would be a pretty niche market would have to be done by a kit manufacturer with a couple other successful aircraft or someone with fairly deep pockets and no expectation of moving out of the red for a decade or two. Liability would be an interesting issue given the additional opportunity for legal mayhem, and I have to wonder where liability law will go if we continue to move towards penalizing industries that we don't care for or don't contribute sufficiently to our preferred sorts of villains.
thinking of some v8 conversions,robinson sticks out,litteraly,as they have three different extensionOnce you add it all up at the end of the project, they're not even that.
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