Twin or single? Pros and cons
 

I'm debating if I should go single engine or twin in a new jet I've ordered. (Yak 130)

While it is nice to still be able to fly in an engine out situation, is the added cost and weight of two engines worth it?

is the sound of a bifurcated pipe horrible enough to justify twins :)

twice the the things can go wrong with two engines. So, are two really more reliable than one, ore do you double your chances of not getting to fly if you have to keep two engines running...

what's your take on this?

I have twine bvm rafale and changing my skymaster mig 29 to twine ,two vt-80s and my next project will be the big 120" long F-18 with two turbines setup ,the biggest advantage is the fast respound and grate power no power losing on the y pipe and the sound it's much dipper and powerful when using two turbines ,twine is way to go the two smaller turbines have much faster respond than one big.

you might have redundancy with two engines but you also introduce more risk paths but putting more equipment in it to go wrong, it is something only the builder can decide, plus the extra cost of another engine will be a factor to consider I have seen a few of these fly and the p200 that was in one I saw was enough power for it so I would go for a single engine and keep it light as possible

Two kingtech 100g cost less than one p-200 + the life time warranty and fix cost for the 25h service ,the weight it's almost the same.

I normally fly JetCat and was going to go with two P-100's but the Kingtech 210 looks promising. Almost half the price as the twin install. But, that bifurcated sound is a bit annoying.

Decisions decisions...

John,

My .02,

Go with the twin set up!! Lets face the real facts as to why most of us got into turbines in the first place, the pure sound and awe affect or we would still be flying whinning ass 2 stroke fan units. Nothing sounds better than a pair of turbines or twin anything for that matter, and you bought an airframe that is perfect for them. Most of the planes built that should have twins, don't have the room for 2 turbines and we run a BIF pipe. Your plane has enough room to put what ever size turbines you want to fly in it. As for the dependability of 2 turbines or double trouble?? I would not use some older tech turbines laying around, I would look into the newest turbines that are plug and play with very little ancillary equipment to install. You could use 2 - K100G KingTechs that will give you a true 44 lbs of push for $2,050.00 each. Or if you want ballistic fun, go with 2 - K140G's that will give you a true 62 Lbs of push for $2,450.00 each. I have a friend that ordered the YAK and is going to use 2- K-140G's in his. I think you will find you can buy a pair of smaller turbines for close to the same price as a large single. Obviously I am partial to KT but you can shop the other turbine companies product and make your own decision. Again, just my .02




Good luck & good flying,


Dirk

The 210 it's nice going to get one at Kentucky .i wish all the new smaller turbines 180-140-100-80-60 will have Cnc compressor .

You are right Dirk. Sound is important. That's also why I don't own EDF jets. And, I've never been a fan of the bifurcated sound either

Was originally planning twin 140's, and may still do so. The Yak is a big draggy plane.

Yes, if you go twins, I would go with the biggest engine that makes sense. With two engines, you double the chance of an engine failure and if the aircraft can't fly on one engine, then you double the chance of an engine-out related crash. Two 140's would be better than two 100's - as long as the added engine weight and fuel capacity required wouldn't make it too heavy...

BTW, I think bi-pipes sound cool - much more like a real aircraft... :)

Bob

JC,

I think a pair of K140G's is a great choice, as the YAK is a very large and draggy plane and the 140's will give you the ability to fly it with authority and plenty of vertical. Again, another reason we got into turbines is the go fast and the pure thrust of turbine power. Aside from the cost difference of the 2 turbines vs 1, the only extra cost for the twin setup is a Y connector and some extra fuel line. If you decide to go with KT turbines, let Barry know when you order them to get you sequential #'d turbines and I will tune them to match on the thrust output for you.

K210G = $3,850.00
K100G = $2,050.00 x 2 = $4,100.00

K140G = $2,450.00 x 2 = $4,900.00


Dirk
KingTech Service

This is true even in full-scale; owners moving to twins from singles don't think of the double-trouble factor at first. Also, it's the old saw, "The remaining engine takes you to the scene of the crash." With center-line thrust setups like you'll have, single-engine ops are much easier but still not fool-proof.

John make sure and check the true fuel consumption on whatever you get.

Hi John.
I would go twin ... that plane is so ugly that you need to give it some charm !!!! ;):D;)

Hope you are doing fine.

Jack

Jack...

Ugly??? ;)

That's from a guy who thinks a Fouga is pretty LOL

Hope you are well. It's been a while.

I actually think the Yak is pretty cool looking. Especially with all the crap hanging under the wings. I am going twin. Decided on two P-140RX

I like it! & your engine configuration on the Yak makes twins a true viable solution. I don't think I'd do a twin turbine A-10, or Airliner because the thrust line is too far off center where the remaining engine could just be a liability, but the Yak or Rafale is ALL GOOD:) With that being said I am probably too cheap to buy 2 new turbines for a project

I've owned and flown a twin BVM Rafale, twin CJ F-18, A-10 and, am in the process of completing another twin CJ F-18. Enjoyed flying all of them immensely! That being said, KISS would still win out, in my book! If you can get enough thrust with a single to perform the way you want, you can't beat the simplicity and, when installed properly, the reliability.

David S

I never owned a twin. I do have a single with Y pipe so I did want to add my observations:
Y pipes suck. A lot of thrust is lost. They are difficult to align and some are worse than others. They also tend to cost a fortune (something to consider in the cost factor IMO).
I may build a twin Su-27 some day but I got to say, In the few jet rallies that I have been to, it seems at least half of the twins never fly due to some issue like one tubine wont start or the RPM doesnt sync. They seem to be higher maintenance and people spend more time fixing them than flying them. But not in all cases.

I suppose a single converted twin could use a straight pipe or be on the bottom of the jet but you want to talk about ugly....

Now the side pipe, that is interesting. Seems to be the best of both worlds if it works.

Twins are just ... COOL. Hard to justify it any other way. You add a new level of complexity, things to go wrong that really outweighs the benefit of being able to maintain flight on 1 engine.

Just like on full scale aircraft you will always have a critical engine. It is the one that is still running! And if you are not prepared for the asymmetrical thrust and change in handling it will be the one that will lead you to the scene of the crash.

But twins really are just plain ... COOL.

I'm putting twins in mine, k140's!, the redundancy part is a nice bonus but its really because its cool and I don't really get the part about doubling potential issues because since I started buying the newer kingtech's I haven't really experienced any problems.

Also i'm fitting a decent gyro to mine that way if I do get a single engine flame out it will help keep everything going in the right direction

The problem was with the bad cables in p-140rx the was the biggest problem know with the rx series ,now the jet fly with trusted p-160 turbines no problems .

Don't forget about the AMA turbine rules...3. For Turbojets and Turbofans single engine static thrust shall not exceed 45 pounds; multiple engine static thrust shall not exceed 50 pounds combined.
I am positive that more than just a few jet fliers in the USA pay no attention to this rule, but shame on all of us if the unthinkable happens by someone who does violate this or any other safety rule.



.

I agree with you a 100% Harley. But I also think the majority of people flying twins are adding bigger engines for two primary reasons:

1. you can run two higher thrust engines at lower RPM for better fuel economy and less engine wear.

2. If the engines are going to be used for something else later, bigger engines gives more flexibility.

This of course requires an airframe that can handle the weight. And, when detuned, its still AMA legal.

Was this with your su-27?

Analyze the trade-offs. A twin power plant a/c would most likely need twice the onboard fuel capacity compared to a single power plant a/c unless the flight time is cut in half or at best considerably less. With the additional power plant and system comes the added weight to the a/c. So you have added power with the additional power plant but the trade-off is the additional weight added to the bird.

Also mentioned is the additional risk of a power plant failure, people I've known who fly full-sized planes with multiple power plants I've heard refer to this as "double trouble" reference. Logical. Additional systems comes added probability of a failure.

Cost most likely isn't too much of an influence on your decision making process so that's probably not much in way of trade-off.

I'd start with analyzing the trade-offs first and work your way forward through the decision making process.

Twin.

Beave