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RV-4 aerobatics

C

coke109

I'm New Here
Hi all

I bought an RV4 about a year ago, equipped with 160hp, FP prop, non inverted fuel and oil system. It's a great plane and I love flying it! Sportsman acro is lots of fun but energy management is definately more demanding than in other aerobatic planes with more power and inverted systems! You really have to get used to the fact that there's no power available at 0 or neg G's.

I'm still trying out different entry speeds for sportsman acro, especially for Immelmans, multiple and hesitation rolls. What's your experience regarding ideal entry speeds?

I know acro can be done perfectly well with my engine set up. Check out this great video:

https://www.youtube.com/watch?v=GojqK3H8AiQ&feature=youtu.be

Cheers
Ivo
 
coke109 said:
I'm still trying out different entry speeds for sportsman acro, especially for Immelmans, multiple and hesitation rolls. What's your experience regarding ideal entry speeds?
Click to expand...

Too many variables with aircraft setup, DA, G-pull, what you're trying to accomplish, and how you want it to look. This is something you must determine on your own. It's common to be concerned with entry speeds starting out, but understand that it's only half of it. The other half is G-loading. Managing L/D (how hard or soft you pull throughout) is just as important as entry speed. Other than snap rolls, entry speed can be whatever you want it to be as long as you fly the airplane within G and airspeed limits. You'll learn what it takes for your setup. RVs can do all the basic maneuvers across a wide range of entry speeds. The builder's manual is just a generic suggestion on getting started, and nothing that's important to follow exactly, unless snap speeds are listed.
 
Look at putting a Moroso 1.5 qt accumulator on the engine. That will guarantee oil to the engine in all attitudes. The cost is a few hundred dollars to do it. Plus you can use it as a pre-oiler for start up. I don't turn my prop until I have 30 psi showing on my O.P. gauge.
 
It's a simple install - a Tee fitting, and the electronic solenoid to open and close it. Do a search on "accumulator " and you will find pictures and specifics. Well worth the money/time
 
entry speeds

coke109 said:
Hi all

I bought an RV4 about a year ago, equipped with 160hp, FP prop, non inverted fuel and oil system. It's a great plane and I love flying it! Sportsman acro is lots of fun but energy management is definately more demanding than in other aerobatic planes with more power and inverted systems! You really have to get used to the fact that there's no power available at 0 or neg G's.

I'm still trying out different entry speeds for sportsman acro, especially for Immelmans, multiple and hesitation rolls. What's your experience regarding ideal entry speeds?

I know acro can be done perfectly well with my engine set up. Check out this great video:

https://www.youtube.com/watch?v=GojqK3H8AiQ&feature=youtu.be

Cheers
Ivo
Click to expand...

Ivo,
Lots of real warnings about entry max speeds >135 mph.
Also entry for snap rolls should be REAL slow.

Daddyman
 
By Design...

coke109 said:
Hi all

I bought an RV4 about a year ago, equipped with 160hp, FP prop, non inverted fuel and oil system. It's a great plane and I love flying it! Sportsman acro is lots of fun but energy management is definately more demanding than in other aerobatic planes with more power and inverted systems! You really have to get used to the fact that there's no power available at 0 or neg G's.

I'm still trying out different entry speeds for sportsman acro, especially for Immelmans, multiple and hesitation rolls. What's your experience regarding ideal entry speeds?

I know acro can be done perfectly well with my engine set up. Check out this great video:

https://www.youtube.com/watch?v=GojqK3H8AiQ&feature=youtu.be

Cheers
Ivo
Click to expand...

Ivo,
Congrats on buying the best sportplane value out there IMHO. Also, welcome to VAF.

I built my RV4 while I was living in base housing in Japan in 1988', flying the F16 for a living. You wanna talk G's, speed and performance? It had a tough act to follow! I wanted a personal airplane that offered many options, mostly being a 180mph Super Cub. Aerobatics was a nice add on.

The original RV ads touted "total performance" which meant, everything. Well, almost.
After 5 years of rivet banging the collection of parts finally flew and I wasn't disappointed. I found my 925lb nimble day fighter to excel at STOL from my 1200" grass strip, 180mph speed and reasonable positive G Aerobatics. In addition to the carbureted 150HP 0-320, I installed a climb wood prop, M34 air oil separator and kept it light. I found it as you have to be a decent aerobat, 1v1 dogfight adversary and cross country machine. After 20 years it's still going strong with its new owner, a retired F18 pilot.

The RV4 does offer great all round performance and economy and by definition in the plans and ads, sport aerobatics. It was never designed to be more than that IMHO, although it does well in that regard, just ask Willyeyeball. :)

Keep it light simple and know your limitations. You'll enjoy it for a long time. Walter Extra design inputs notwithstanding...
V/R
Smokey
 
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RV-4 Aerobatics

Hi Ivo,
I just started flying competition aerobatics in my -4. I have a carbureted engine. The -4 is certainly capable of being a credible contender in Primary and Sportsman. Intermediate would be a stretch. Advanced and unlimited - not likely.

I highly recommend you install at least the air/oil separator portion of either the Christen or Raven systems. Otherwise, you'll be pouring oil overboard anytime you are inverted with any negative g on the airplane. I put a 1/2 Raven on mine and it made an order of magnitude difference in the amount of oil getting spit overboard and onto the belly. You might also consider extending your breather line to the tail. The extended breather line is called out in the -4 plans.

Fuel injection will allow you to include more interesting figures in your free sequences but it is definitely not required to fly the current Sportsman sequence. If I go the fuel injection route, I'll install the Airflow Performance system. I looked at pressure carbs and throttle body injection and rejected them as either too dated or too problematic. The Airflow Silverhawk system is a nice, almost form-fit replacement for my carb.

You'll need a parachute. The Strong RV-4 chute is perfect. The seat pack fits precisely between the back of the spar and the seat hinge. The best part is that it doesn't push you any further forward. I found every back pack chute I tried was unacceptable because it pushed me forward too much.

An aerobatic harness is a big plus. I started out with the glorified automotive style belts. Painful and I was moving all over the place during aggressive negative maneuvers. I recently installed a Hooker ratcheting harness. It was an easy replacement and the difference is remarkable. Highly recommended.

As to entry speeds, I think you have a wide range of choice in the RV-4. Generally, faster is better and, as the old aerobatic saying goes, Vne is not just a limit, it's a target! Your entry speeds aren't near as important for most maneuvers as your exit speeds at the top. Eighty (80) knots is my minimum speed over the top in looping maneuvers. Can I do it slower? Sure, but it will be an egg, not a competition credible figure. I kick the rudder at 40 Knots on a hammerhead. Snap rolls are one maneuver where, at least for me, entry speed is critical. I cannot consistently get a good snap roll unless I enter right about 85 Knots. Slower and it ends up being a wallowing barrel roll. Faster and, assuming you are really committed to slamming in full rudder at higher speeds, you'll likely get an interesting gyroscopic departure of some undetermined type. I certainly would not try snapping the airplane above Va - around 105 knots in my airplane at aerobatic weights.

Your fixed pitch prop will also require that you watch your downline speeds carefully to avoid overspeeds. Pulling power may be required and don't be afraid to do so. I pull power on my 180/CS setup occasionally, especially if the lack of oil pressure to the prop threatens a potential overspeed.

For me, the most limiting characteristic of the -4, and RVs in general, is the roll rate. Getting the airplane around requires a lot of time and a lot of box space in some figures.

Competition aerobatics is a blast. The learning curve will likely be steep but give it a try. Most recommend flying primary in your first contest if, for no other reason, that all the administrative aspects of the contest will consume a lot of your available brain bandwidth!

Enjoy your -4. It's a great airplane!
Best regards,
Randy
 
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designerX said:
Nice video! Thanks for sharing.

What prop and pitch do you have? I could not see your airspeed indicator but feel I would over speed my FP cruise pitched Sensenich ‐4 if I held the down-line as long as you have in a couple of maneuvers.
Click to expand...

I could be mistaken, but I think that's Sabre25 doing his thing in Colorado.

I don't think I've seen his plane from that perspective - last time I saw it, I was looking back at it's nose while straining under Gs...;)
 
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For those of you with FP props, simplify your life and ignore the tach during acro. Seriously. You will not hurt anything by going well beyond 2,700 RPM for a few seconds on a downline. We Pitts S-1 pilots have been turning 3,300-3,400 RPM on standard IO-360's for decades with no ill effects. And I can't imagine folks with FP props on RVs are running such flat pitch that you'd even see RPM this high at full power before hitting Vne. If your prop has an RPM limit, obey that. If you're running a metal Sensenich or Catto, don't worry about it. Focus more on the ASI and pulling power as needed to control airspeed, not RPM.
 
Hey Chiefpilot, when are you coming out west for another go? You're a worthy adversary and gave me a real workout, but heck, what do I know about aerial fighting :)

In query to another post, the set up is a 160hp Lyc with a Catto 70-70 prop. As Sandifer says, the engine RPM no big deal, I often exceeded 2700 by a number I won't disclose but you do have to keep an eye on your speed. Speed in the Pitts on the other hand is not an issue and I fly her at full throttle even on a downline also at high RPM.

The video was an airshow routine I did to demonstrate the very capable performance you can get out of a light, simple build and relatively inexpensive acro machine.

Cheers,
"Cobra", aka "Saber25" or occasionally Hans
 
It's a.... http://www.smokingairplanes.com/ system with a 3.5 gallon tank located in the aft baggage area. It smokes for a 15 minute airshow while show center and the tank can be removed in less than 5 minutes if you need the aft space.

Cheers, Hans
 
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