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RV-4 Aerobatics 2up

NorthernRV4

NorthernRV4

Well Known Member
Interesting video. I know the general consensus here is that the -4 is most often outside of it's aerobatic envelope in both gross weight and CG range with 2 adults onboard but this shows that it can be done safely if precautions are taken. The comments are a good read too.

Not starting a flame war, just good discussion on the subject. For those who don't know about Stu's channel, go check it out.

https://youtu.be/i-mxAisu6OQ
 
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Interesting video. I learned a little and picked up some good tips. In my RV4 (980#), I am within the aero envelope with me (200#), 13 gallons fuel, and a 121# passenger for both takeoff and landing with 8 gallons. No baggage. Haven’t done that yet. Solo only, full fuel, no baggage is within the aero envelope no matter how much fuel I burn off.
 
980lb is pretty light. Engine/Prop? I would guess Stu is a bit more than 121# He never did talk about engine/prop on C-FJRQ but I would guess 160hp FP
 
Great video, and I don't judge.

I enjoyed watching it! My -4 weighs in around 950# O-320 and wood prop. Im not an expert at Acro, in fact basic gentleman stuff is it. I have plans to do some really good training in the near future, and I respect VAN's recommendations for all the obvious reasons. I also respect the possible maneuver go wrong over G in ANY configuration with ANY aircraft type, which is the part that we all must pay the most attention to. 707's weren't meant to roll, but Tex made it look easy. Shrike Commanders weren't meant to do what Hoover did while pouring iced tea with the engines off, and the list goes on and on. I really hope to hone in on the upset/botched maneuver recovery scenario, and get my Acro in my -4 to the level of safety I can be comfortable with. Stu, and the many -4 Acro guys on the forums really help me prepare myself for the future training I seek.
 
My 980# RV4 has an O-360 with a carbon Sensenich GA prop. I re-weighed it after I put that prop on, so I know it’s accurate. Any time I have someone in my back seat, I have to be very careful with checking CG, which is more critical after burning fuel. Aft CG limit is easy to reach in my RV4 with someone in my back seat. I only do acro solo. The RV4 is great for positive G acro, the lighter, the better. Like Stu says in the video, the RV4 practically flys itself through some of the maneuvers. You have to be careful when your nose is pointed down though, also as Stu mentioned. Speed picks up very quickly, especially with a fixed pitch prop, and having markers during certain maneuvers, like those clover leafs in the video, protects you from getting yourself in a dangerous position.
 
Training

Yup proper training and then get really comfortable. After an intro like that I'd clear him to fly single rolls only about 2000 AGL - nothing else. When you point nose of an RV down you better a plan - G and airspeed - and have an out.
 
CG

Nice video

Im pretty familiar with RV-4 acro. Any chance you could show us your weight and balance calculations for that flight? My -4 also has a light prop so Im curious what the numbers look like.

Cm
 
A long time ago in RV time at Oshkosh when Alan Tolle used to do most of the talking at the Vans forums I saw Van almost explode when asked about 2 up acro in the 4. He was more than adamant that the 4 was a 1 up acro. Got the attention of the forum

Bob Grigsby
Flew my Cub today
Fighting a Stromberg on my 3 so I can start it for the first time
 
Rv-4 became uncontrollable

RV3Bob said:
A long time ago in RV time at Oshkosh when Alan Tolle used to do most of the talking at the Vans forums I saw Van almost explode when asked about 2 up acro in the 4. He was more than adamant that the 4 was a 1 up acro. Got the attention of the forum

Bob Grigsby
Flew my Cub today
Fighting a Stromberg on my 3 so I can start it for the first time
Click to expand...


Its one thing to do some rolls but anything that puts you inverted at a slow speed might become a high pucker factor experience. I cant recall the details but I think an RV4 and its crew were lost doing aft cg acro out here some years ago. It would be very easy to over G the airplane too.

But still I enjoyed the video.
Cm
 
RV-4 Acro w/Backseater

I’ve been building and flying RV-4’s since the days when Van would fly his 4 to fly-ins and pass out brochures while standing in front of his 4. Van is an engineer and his numbers have real meaning and from an article he wrote: ( paraphrasing) The Laws of Physics don’t care about your rationalizations they know what your airplane weighs. He built his planes light and if I recall correctly his prototype 4 weighed 895lbs. With that being said Van built the 4 with the capability of aerobatics with a passenger. In his early newsletters he would caution that adding too many creature comforts would render your 4 a single pilot aerobatic ship. If 2 pilots and fuel can be flown under the 4’s Aerobatic gross weight of 1375 lbs and rear CG limits, done with proper instruction you are within the design limits of the airplane. There’s nothing inherently wrong with 2 up aerobatics. Where we get in trouble is we now consider 1000 lb RV-4’s the norm. In the early days of RV’s you would be considered a Heretic to build such a plane. In 1992 while driving through Oregon on our honeymoon we visited Van’s home/shop and he gave my then wife a ride in his RV-4 and this ride included some light aerobatics.
 
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