"Why not build a twin?"

[tjo]

Originally Posted by joe gremlin

This is a common argument against twins and its lack of validity is easily established. The chances of an engine failure don't matter. What matters is the options you have available after a failure.

I always like to present the following scenario to twin nay-sayers. You and your spouse are on an island. Your spouse develops a strange illness and needs medical attention on the mainland ASAP or impending death could result. No ferries available, no boats to rent charter borrow or steal, no scheduled flights or charters planes available.

The airport operator has two planes he'll let you borrow. A single and a twin. But he warns you that both have wonky engines and it wouldn't shock him if either one had an engine failure in the next 40 minutes of flight. The mainland is a 90 minute flight. Assuming you're current and proficient in both singles and twins, which one you gonna take? I defy anyone to pick the single in that scenario.

Next time I'm in that scenario I'll let you know what I end up deciding.

(Sorry, couldn't resist)

Tim

[John RV8]

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

http://www.grayeagles.net/ARTICLES/J...;s%20p-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.

[rwtalbot]

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.

[rjbob]

Just...wow!
I hope he gets to Oshkosh this year.

[F1R]

Originally Posted by rjbob

What make & model jet was it?

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]

Originally Posted by Sig600

The kit itself is north of $110K.

Add two IO-320's (what it uses), props, and a panel... you're into it another $100K easy. Interior, building, etc... you'll be $300K before it ever moves under it's own power. It'll be a sexy $300K though.

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]

Really nice flying twin kit here:


http://en.wikipedia.org/wiki/Rutan_Defiant

[DanH]

Originally Posted by John RV8

Jim O'Hara's P-38

http://www.grayeagles.net/ARTICLES/J...;s%20p-38.html

I'd forgotten about that project. One of the most interesting homebuilts ever.

[Low Pass]

Originally Posted by DanH

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]

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.