M

Michael Brown

Active Member
As most of you know I am building a 7. I am currently flying a C-150 and I am really tired of my Dad flying circles around me in his 185 hp RV-4 w/ a 3 blade catto. I am planning on a Barret IO-390 with a Hartzell BF CS prop. I am tired of the abuse and have to do whatever it takes to be faster(except put a 540 on the nose). What do you guys think? Thanks in advance.
 
Michael,

Start by building it as light as you can.

Go with the electronic ignition of your choice.

Get the rigging right, including the leg, wheel pants, and intersection fairings.

Then work on fairing in anything that sticks out.
 
Its a challenge

So I do have a challenge after all. I am planning on the james cowl. I know I will be heavier, but I am building it as clean as possible. I will post the results in a couple years when I finish building.
 
Clean/Light

Build it clean and light. Also consider the Whirlwind 200RV prop. It is 35lbs lighter than the Hartzell and was designed for the RV airframe. It is extremely smooth and light.
 
Unless I've missed something, I haven't seen a lot of action on the 390 engines or people's experiences with them. I'll be very interested to hear how it goes if you head that direction. I've been sternly directed by a buddy who's just finishing an 8 ("no, really, you should really check out the 390. Really."), and it is a pretty compelling solution, even if you save money by going with a fixed pitch prop.

More "power" to ya (dumb pun intended). Let us know how it goes.
 
IO-390

We have three Barrett IO-390 RVs in the local area (that I know of); one RV7 (flying, with CS Prop), one RV7A (panel is done, working on FWF), and one RV8 (almost ready for first flight).

I've flown the RV7...and it's an incredible ride. Leaps tall buildings. Faster than...well you get the idea.

Search the forums using "IO-390" and you'll pull up quite a few references.

Mike
 
Dayton Murdock said:
FASTER = MONEY!:D
Click to expand...

Only when you make the wrong choice up front.:)

Seriously, it is easier to get more speed by reducing drag than by increasing hp.

If you want significantly more power, a turbocharged rotary is the way to go- it is good for 350-400 hp with minimal weight penalty (compared to a IO-360/390) and will cost a whole lot less, maybe half (in the $10K range). Base engine approx $2K, weighs ~200 lbs. with flywheel. Dont use OEM automotive turbo.

A naturally aspired 6-port Renesis engine (or a peripheral ported older 13B) is good for 250-270 hp with a tuned intake. It will not require limiting power, due to heat, at full throttle.
 
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Don't know which rotary specifically you are referring to, have heard varying reports of success there.

Looks like Rotamax just lost one of their test designs - click here.
 
I have to stay with in reason. I don't have an endless amount of funds. I know that if I am able to smoke him, he will rebuild the 4 into a rocket. Then the only thing I will beat him on is fewer fuel stops. Thanks for your thoughts guys!
 
Rotary

Where does one find info on a non automotive rotary? What were they designed for? I know rotarys are great engines, just don't want a car engine on my airplane. High failure rate, due to not being designed for our requirements.:confused:
 
Easy speed mod.

Michael Brown said:
As most of you know I am building a 7. I am currently flying a C-150 and I am really tired of my Dad flying circles around me in his 185 hp RV-4 w/ a 3 blade catto. I am planning on a Barret IO-390 with a Hartzell BF CS prop. I am tired of the abuse and have to do whatever it takes to be faster(except put a 540 on the nose). What do you guys think? Thanks in advance.
Click to expand...

An unamed person at Van's when asked how to increase performance on an RV-6a was alleged to have told the hefty inquirer "Why don't you lose 20#?"

Every time I look at my RV thinking of performance mods, I ask myself the same question...

Jerry
 
Read post by Bob Axsom

Read Bob's posts. He is into racing and has some tips for you. Things like cleaning up gaps.

Fair everything you can.

Consider sabotage as a last resort!!!
 
Reducing drag

Michael,

The easiest way to more speed is definitely through drag reduction. In a piston powered airplane, speed varies with the CUBE of the installed HP. For example, to go twice as fast you'd need 8 times more HP. The equation looks like this:

HP Ratio = (Higher Speed / Lower Speed) ^3

So, for the money, I'd recommend an aggressive drag reduction program. Some areas that should yield good results are:

1. Cooling drag. Work on good tight baffling. Maybe invest in a plenum for the high pressure side of the engine, and a more efficient cowl. Also inlet diffusers are proven to improve cooling drag because they manage momentum losses in the flow. I also know the cowl outlet area is too big for cooler weather.
2. All fairings should be very clean and tight fitting - no air gaps.
3. Keep the plane light.
4. I KNOW our aileron design is draggy. The old Friese aileron design was obsolete by 1940. Go look at a Cirrus, Lancair, or Beechcraft for better ideas. I understand changing the ailerons involves more than meets the eye, so get a good engineer to help out. I'd be glad to assist you in this area.
5. Installed HP is fine, but expensive. Invest also in an efficient prop. Take a look at the new Hartzell blended airfoil propeller, or the Whirlwind if you're so inclined.

Your choice of a Barrett engine is excellent - I'm jealous! I had Monty build an IO360 for my former RV4 and it was a super engine. HP is part of the deal here too, despite my ravings about drag reduction.

Best of luck - hope to see your plane some day! :D
 
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If you are looking for a comparison.
I fly a 200 hp RV8 with three blade hartzell. A good friend has a 200 hp fixed RV4.
Top speed is neck and neck but I can outclimb him( maybe 200fpm) with my CS prop.
 
Faster

Michael I know a formation pilot who has the following. RV8, stock IO-360
MT prop and dual Lightspeeds. That's it, nothing fancy just an airplane. He took no steps to be "light" or clean. He built it to the plans. The 8 is Miss Izzy owned by Ron Schreck of North Carolina. Ask anyone he flys with. It is fast 175kts cruise down low. I was in a drag race with him and two other 8's ( I have a FP o-390 7A) he smoked us all. After he passed us with a passenger he barrel rolled us. I would reccomend an angle valve 360 rather than the 390 because it is a cleaner installation.
Tad Sargent
7A
Team RV
 
Thinkin????

Tad.......
What do you mean by cleaner install? They are relatively the same engine. Whats the difference about the install?
 
Turbo Wankel Rotary Cost

rtry9a said:
Only when you make the wrong choice up front.:)

Seriously, it is easier to get more speed by reducing drag than by increasing hp.

If you want significantly more power, a turbocharged rotary is the way to go- it is good for 350-400 hp with minimal weight penalty (compared to a IO-360/390) and will cost a whole lot less, maybe half (in the $10K range). Base engine approx $2K, weighs ~200 lbs. with flywheel. Dont use OEM automotive turbo.

A naturally aspired 6-port Renesis engine (or a peripheral ported older 13B) is good for 250-270 hp with a tuned intake. It will not require limiting power, due to heat, at full throttle.
Click to expand...

I think you are very low on your estimate for a turbo wankel. Don't forget you need a PSRU, fuel injection, custom engine mount, custom manifolds, a very large turbo, wastegate, intercooler, radiator, and oil cooler, and if you are doing it right, a blow off valve. Easily $10K here.

To do the base engine right you need all new parts with some custom machining and ceramic apex seals. Closer to $8K.

I initially was going to go turbo peripheral port 13B-REW, but after pricing it out, it seemed a lot of money and would add at least a year to the project, and it limits your propellor choices.

The factory production Mazda wankel rotaries ARE plenty tough enough for aircraft use with a few modifications. Of course the ancillary systems are the most dangerous/experimental portion of this type of installation.

$.02

Hans
 
CE196 said:
Where does one find info on a non automotive rotary? What were they designed for? I know rotarys are great engines, just don't want a car engine on my airplane. High failure rate, due to not being designed for our requirements.:confused:
Click to expand...

High failure rate? Rotary engines are much better aircraft engines than automotive imho. They are designed for, and operate best, where continuous high hp/ high rpm operation is needed, as in auto racing and aircraft use; they are less suited where high torque/low rpm is needed in stop and go traffic. They are extremely reliable and durable when modified correctly.

You can get an aircraft only rotary engine from several sources, but they are no better than the Mazda rotary's, and possibly worse, in that they are newer and less tested.
 
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