Next time I'm in that scenario I'll let you know what I end up deciding.
(Sorry, couldn't resist)
Tim
Van's Air Force
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"Why not build a twin?"
- Thread starter Palamedes
- Start date
Next time I'm in that scenario I'll let you know what I end up deciding.
(Sorry, couldn't resist)
Tim
John RV8
Well Known Member
Cool twin project
Here is a neat homebuilt twin for y'all
Check out this project. I hope the link works, if not it is worth the effort to copy and paste it to see it
Jim O'Hara's P-38
www.grayeagles.net/ARTICLES/Jim O'Hara's p-38.html
Jim O'Hara is a member of EAA chapter 493 in San Angelo, Texas. He is a retired college ... Fifteen years ago, he began construction of a 2/3 scale P-38.
Here is a neat homebuilt twin for y'all
Check out this project. I hope the link works, if not it is worth the effort to copy and paste it to see it
Jim O'Hara's P-38
www.grayeagles.net/ARTICLES/Jim O'Hara's p-38.html
Jim O'Hara is a member of EAA chapter 493 in San Angelo, Texas. He is a retired college ... Fifteen years ago, he began construction of a 2/3 scale P-38.
How about it Van?
None of us buys an RV to save money. Just look at the people queued up to build RV14's with an engine big enough to power a six seat aircraft. There is no shortage of people who want to shell out heaps of $'s for expensive aftermarket mods. If you can build a reliable single engine RV or Rocket you can do the same with a twin.
Personally, I'd build any twin engine kit that Van brought to the market just because I would love to build and fly one. No one in the industry can deliver such a quality, value for money kit.
Who wouldn?t rather have something new over the $40k annual machines on the market? I could never go back to "certified tax" where disgruntled old engineers hold owners to ransom all day long. These guys will be extinct before long and that?s reason enough to own the RV20.
How about it Van? Just tell me when to send the cheque? I bet the first Oshkosh demo rides are sold out months in advance and most of these naysayers will be drooling.
I figure a pair of 320/360's would be about right and not too much more in price than a single 540. I bet most of the punters will want 600hp a side though - so better have a turbine option.
None of us buys an RV to save money. Just look at the people queued up to build RV14's with an engine big enough to power a six seat aircraft. There is no shortage of people who want to shell out heaps of $'s for expensive aftermarket mods. If you can build a reliable single engine RV or Rocket you can do the same with a twin.
Personally, I'd build any twin engine kit that Van brought to the market just because I would love to build and fly one. No one in the industry can deliver such a quality, value for money kit.
Who wouldn?t rather have something new over the $40k annual machines on the market? I could never go back to "certified tax" where disgruntled old engineers hold owners to ransom all day long. These guys will be extinct before long and that?s reason enough to own the RV20.
How about it Van? Just tell me when to send the cheque? I bet the first Oshkosh demo rides are sold out months in advance and most of these naysayers will be drooling.
I figure a pair of 320/360's would be about right and not too much more in price than a single 540. I bet most of the punters will want 600hp a side though - so better have a turbine option.
C510 Mustang 1
The problem is not the make or model, it was the compressor wash that was done without flying and drying the engines , before it was put away.
It was quite a sequence of events in hindsight.
The morning of the dual oil pressure loss it was pulled out of a warm hangar into -26 deg C , then quickly filled with -26 deg C fuel before cranking up and doing a rolling checklist to avoid ice buildup before take off.
On take off we went through 3000 feet of light mixed icing in seconds.
13 minutes into the flight and passing 32500 for 38K planned, the master warning lit up. The RH oil pressure dropped to 2 psi from normal in less than 3 seconds. Right side was shut down as the pressure hit zero. While calling ATC for the turn around, the left side did the same as the right. I heard something that sounded like "Cheese is nice" from the other seat, then he looked at me and said we won't be shutting this one down.
The AMO was the same company that looked after the provincial air ambulance fleet at that time.
If you ask me, the heat from the oil in the PW615's was not sufficient to overcome the volume of cold in the -26 Deg fuel and the oil got too viscous in the filter elements (right after the heat exchangers) Or it was ice crystals from water in the oil system from the compressor wash.
The pressure in the LH engine recovered slightly before landing, but that was from the bypass valve unseating. Evidently the damage to the bearings was done while there was no pressure for a few moments (or minutes) before the bypass unseated.
To answer your question it was a Mustang 1 / C510.
The AMO, the owner and the PIC were all happy to believe the G1000 had a tiny brain fart. The truth hit home when the left side seized a few days later.
I am reminded the Robinson R44 helicopters have a lower engine failure rate per 100K hours with IO 540's than Bell 206's do with allison turbines.
The problem is not the make or model, it was the compressor wash that was done without flying and drying the engines , before it was put away.
It was quite a sequence of events in hindsight.
The morning of the dual oil pressure loss it was pulled out of a warm hangar into -26 deg C , then quickly filled with -26 deg C fuel before cranking up and doing a rolling checklist to avoid ice buildup before take off.
On take off we went through 3000 feet of light mixed icing in seconds.
13 minutes into the flight and passing 32500 for 38K planned, the master warning lit up. The RH oil pressure dropped to 2 psi from normal in less than 3 seconds. Right side was shut down as the pressure hit zero. While calling ATC for the turn around, the left side did the same as the right. I heard something that sounded like "Cheese is nice" from the other seat, then he looked at me and said we won't be shutting this one down.
The AMO was the same company that looked after the provincial air ambulance fleet at that time.
If you ask me, the heat from the oil in the PW615's was not sufficient to overcome the volume of cold in the -26 Deg fuel and the oil got too viscous in the filter elements (right after the heat exchangers) Or it was ice crystals from water in the oil system from the compressor wash.
The pressure in the LH engine recovered slightly before landing, but that was from the bypass valve unseating. Evidently the damage to the bearings was done while there was no pressure for a few moments (or minutes) before the bypass unseated.
To answer your question it was a Mustang 1 / C510.
The AMO, the owner and the PIC were all happy to believe the G1000 had a tiny brain fart. The truth hit home when the left side seized a few days later.
I am reminded the Robinson R44 helicopters have a lower engine failure rate per 100K hours with IO 540's than Bell 206's do with allison turbines.
Toobuilder
Well Known Member
Yep, and a no "assembly required" Aztec can be had all day long for $40k today.
...that remaining $260k buys a lot of gas and parts.
N395V
Well Known Member
I'd forgotten about that project. One of the most interesting homebuilts ever.
*THIS* is why a twin!!! Last I heard of the project, he was getting close. Great to see it flying!
Moondog
Well Known Member
twin engine, single prop
Along the lines of Bill R. (?How about putting two engines in the same engine compartment??):
A twin?s safety comes from redundancy, of course. Its problem is the sudden change in forces following engine failure. However, with just a single prop and two engines, the redundancy would be there for safety but without subsequent loss of control.
Lots of ways to do this. Here are two. The engines could be in-line, counter-rotating, driving a common alternator. Or they could be on the wings, each with its own alternator, connected to a common electric drive motor with a single prop; furthermore, consider that with no prop sticking out in front of each engine, the design would be more aerodynamic than the typical twin.
Could even use a battery bank in place of one of the engines. It's more than we could fit in our little planes, but it's a thought.
Along the lines of Bill R. (?How about putting two engines in the same engine compartment??):
A twin?s safety comes from redundancy, of course. Its problem is the sudden change in forces following engine failure. However, with just a single prop and two engines, the redundancy would be there for safety but without subsequent loss of control.
Lots of ways to do this. Here are two. The engines could be in-line, counter-rotating, driving a common alternator. Or they could be on the wings, each with its own alternator, connected to a common electric drive motor with a single prop; furthermore, consider that with no prop sticking out in front of each engine, the design would be more aerodynamic than the typical twin.
Could even use a battery bank in place of one of the engines. It's more than we could fit in our little planes, but it's a thought.
There's a lot of empty space in the aft fuselage of an RV-6... With a couple of air intakes on either side of the fuselage, a small turbine inside that empty cavern, and an exhaust port out either side of the tail, you could have a poor man's Tutor. Mind you, you'd probably need to move either the cockpit forward, or the wing back...
http://airforceapp.forces.gc.ca/v2/netpub/index-eng.asp?rid=7803-IS2008-1078
http://airforceapp.forces.gc.ca/v2/netpub/index-eng.asp?rid=7803-IS2008-1078
JonJay
Well Known Member
These guys are building one. A big investment to copy an airplane that never flew, and still hasn't. It's "historic significance" is, well, it never flew, but if it had, it would have been, huh? err.... I love the self justification we all do to support our own crazy ideas. I like these guys....
This is experimenting on a grand scale. Go for it....
http://bugatti100p.com/
This is experimenting on a grand scale. Go for it....
http://bugatti100p.com/
Yeah... But then you're flying an Aztec. Arguably one of the ugliest airplanes ever built.
N402RH
Well Known Member
For less than the price of a RV-10 you can have a Pressurized, De-Iced, In-line Twin.
http://www.controller.com/listingsdetail/aircraft-for-sale/CESSNA-P337-SKYROCKET/1975-CESSNA-P337-SKYROCKET/1324479.htm
Rob Hickman
N402RH RV-10
http://www.controller.com/listingsdetail/aircraft-for-sale/CESSNA-P337-SKYROCKET/1975-CESSNA-P337-SKYROCKET/1324479.htm
Rob Hickman
N402RH RV-10
For less than the price of a RV-10 you can have a Pressurized, De-Iced, In-line Twin.
http://www.controller.com/listingsdetail/aircraft-for-sale/CESSNA-P337-SKYROCKET/1975-CESSNA-P337-SKYROCKET/1324479.htm
Rob Hickman
N402RH RV-10
One or two annuals, you'll wish you bought the 10!
Palamedes
Well Known Member
If you are worried about the odds being twice as likely that you will have an engine failure because you have two engines then it would make sense that having zero engines would make it safer yet.
Actually.. I have some glider time and I thought it was extremely safe. I enjoyed it thoroughly.. so there might be something to what you're saying since I never worried about the engine quitting!
OMG that's amazing I want one..
Exactly. I think the RV20 is a fantastic idea. OR, we can get them to make an RV-38! =)
joe gremlin
Well Known Member
Just about every home builder I've ever met has at one point or another been asked some form of 'why spend $X building this thing when you could spend $x and get a <insert low performing 1960's POS with **** radios **** paint **** interior **** performance> and be flying today with lots of money left over for fuel and maintenance'.
And every single time I've heard someone ask that, the homebuilder in question would immediately launch into a long diatribe about how when they get done they'll have a 'brand new plane that will cost far less than any other currently available new airplane and will perform far better than any currently available new or used airplane in its class' yada yada yada...
Some of the comments in this thread are really starting to remind me of a story involving a pot, a kettle and a certain very dark color. I'm just sayin'.
And every single time I've heard someone ask that, the homebuilder in question would immediately launch into a long diatribe about how when they get done they'll have a 'brand new plane that will cost far less than any other currently available new airplane and will perform far better than any currently available new or used airplane in its class' yada yada yada...
Some of the comments in this thread are really starting to remind me of a story involving a pot, a kettle and a certain very dark color. I'm just sayin'.
joe gremlin
Well Known Member
What happens when the single electric drive motor fails?Along the lines of Bill R. (?How about putting two engines in the same engine compartment??):
A twin?s safety comes from redundancy, of course. Its problem is the sudden change in forces following engine failure. However, with just a single prop and two engines, the redundancy would be there for safety but without subsequent loss of control.
Lots of ways to do this. Here are two. The engines could be in-line, counter-rotating, driving a common alternator. Or they could be on the wings, each with its own alternator, connected to a common electric drive motor with a single prop; furthermore, consider that with no prop sticking out in front of each engine, the design would be more aerodynamic than the typical twin.
Could even use a battery bank in place of one of the engines. It's more than we could fit in our little planes, but it's a thought.
DaleB
Well Known Member
Or the very complex electronics required to drive an efficient, lightweight electric motor?
And therein lies the problem with trying to design redundant systems...unless all the components are redundant and cross-strapped, you just move the single-point failure around.
We spend years on projects I work on engineering the single-string vs. dual-string designs, redundancy, hot-swapping, cross-strapping, single-fault tolerance exceptions, etc. Not an easy task...
David-aviator
Well Known Member
...but Boeing and McDonald-Douglas engineers did a good job over the years, the systems worked well and still do.
Such redundancy is not practical at this level - few can afford it.
The operation is loaded with single points of failure starting with the engine and prop, that's the way it is and we live with it quite well. Know the limits, accept the risk and stay in the box. It is not as safe as watching TV but worth it.
Hanging 2 engines won't make it better but it will cost a lot more.
skylor
Well Known Member
...except for the DC-10 hydraulic system...
Let's spoil this topic with some of the wilder variants. Most (not all) of them feasible IMHO.
Airelle. Flew, but underpowered (2X40 hp for a two-seater...)
TT62 Alekto. Excellent plane where it concerns demonstrating wing/prop interference, drive-train issues, interference and intersection drag...
A conceptual design of one of HBA's members. If you can get over the TV issues of the drive shaft, it seems like a perfectly reasonable design for a wide range of engines.
Same author, but way up in terms of complexity:
One of the wilder ideas. Push-pull with a pusher engine on the fuselage pod, allowing to shift the prop arc of the tractor engine fwd, otherwise close to the Be141:
A single-seater on two half-VW's or so.
Gumbo. Fairly far along in the build process, Reno racer with two IO-720's:
Personally I'd fancy something with 2+2 seats and 2X 100 hp. Either a scaled down Rutan Boomerang, or something between the Powers & Bashforth Minimaster and the Cessna 337, either with fixed gear.
jdeas
Well Known Member
dual RV4 or 8 fuse
How about the P38jr look?
Just buy two RV-10 fuse kits and start cutting?
How about the P38jr look?
Bubblehead
Well Known Member
It's not practical but it's fun to think of two RV4's in an F-82 configuration. I think someone photo-shopped up something like that. It would be a head turner. Definitely in the philosophical opposite direction from what Richard V. has been doing all these years.
Actually Van himself came up with this idea back in the early to mid '90s. He published it in the RVator as an April Fools joke. He later regretted it when people tried to order kits. It was to be the RV-8, the first 4 place, twin engine, retractable RV.
David Paule
Well Known Member
Twin Twister
Here's another of the twin-fuselage aircraft - taken from the Twister website:
I kinda like the synchronized props.
Dave
Here's another of the twin-fuselage aircraft - taken from the Twister website:
I kinda like the synchronized props.
Dave
rmartingt
Well Known Member
With a light airplane like an RV? Excel.
Really, software isn't necessary, but it sure makes some things easier/less tedious. It doesn't replace actually knowing what you're doing, though.
RVTrumpet
Active Member
HAHAHAHA That's funny...
bhassel
Well Known Member
There always the Gemini which never got produced by Zenith...
http://zenithair.com/gemini/gem-what.htm
using 2 80hp Jabiru's
Bob
http://zenithair.com/gemini/gem-what.htm
using 2 80hp Jabiru's
Bob
rmartingt
Well Known Member
Except it's not.
Most of the work in designing an airplane like this is calculation, and a lot of it is repetitive and/or iterative. Excel makes that process less tedious. CAD is useful but it doesn't design for you; CFD and FEA take a lot of skill and experience to be used properly, and except for very special cases light airplanes don't warrant them.
Remember, Van designed the early RVs without CAD or other fancy tools, as did other notable homebuilt designers.
Excel
The right tool for the right job. John Roncz (Voyager wings and prop, RV-9X wing) wrote a series of articles in the 1990s when Sport Aviation actually had some content. His tool? Excel. And you can build the same Excel spreadsheets he did.
Have a look here:
https://rtfmaero.wordpress.com/library/downloads/
The right tool for the right job. John Roncz (Voyager wings and prop, RV-9X wing) wrote a series of articles in the 1990s when Sport Aviation actually had some content. His tool? Excel. And you can build the same Excel spreadsheets he did.
Have a look here:
https://rtfmaero.wordpress.com/library/downloads/
David Paule
Well Known Member
There are any number of excellent books about it all. One that I especially like is Perkin's and Hage's "Airplane Performance Stability and Control." It's oriented to the guy with a slide rule, pencil and paper, and is a good one-book reference. Having a calculator or spreadsheet, you'll be far ahead of the fellow back in 1960 who used the book.
It doesn't include structural design, though.
Dave
It doesn't include structural design, though.
Dave
Twins
In the early 50's, Harold Wagner from Portland OR joined two Piper PA11 fuselages together with a prop spacer to allow the props to overlap. He later put two engines on the front of a Piper Tri Pacer.
Someone else joined two Ercoupes together similar to the PA11's.
Google twin engine piper tripacer for photos.
In the early 50's, Harold Wagner from Portland OR joined two Piper PA11 fuselages together with a prop spacer to allow the props to overlap. He later put two engines on the front of a Piper Tri Pacer.
Someone else joined two Ercoupes together similar to the PA11's.
Google twin engine piper tripacer for photos.
Vans RV38???...
3 RV8 fuselages
2 empanages
2 pairs of wings (only partial on 2nd set - root section)
2 fire wall forwards
1 finish kit
Room for retracts in the side hulls and nose of center section.
Pair of IO320's.
A little engineering and the ultimate RV play toy.
Guns optional.
3 RV8 fuselages
2 empanages
2 pairs of wings (only partial on 2nd set - root section)
2 fire wall forwards
1 finish kit
Room for retracts in the side hulls and nose of center section.
Pair of IO320's.
A little engineering and the ultimate RV play toy.
Guns optional.
Palamedes
Well Known Member
Amen! They have been making Aircraft for a lot longer than there have been computers.. the magic is knowing what to calculate..
Who says?!
One reason it's "magic" is that the fundamental equation for fluid dynamics - the Navier-Stokes equation - has no known general solution in 3 dimensions. IF you can find one, it's worth $1,000,000; this is one of the so-called millennium prizes in mathematics.
bhassel
Well Known Member
And the Dyn Aero Twin R, which flew 4 years ago but the company subsequently went bankrupt and was acquired. 2 x 100 hp Rotax 912 ULS motors and 2+2 seating. It was listed as a kit but there was talk of certification, which seems to almost guarantee you'll never be able to actually buy one... the MCR 4S on which it was based appears to still be available though.
Something more capable, like an RV-10T with pair of IO-340s might do the trick? (would it still fly on 1 engine?)
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