Flight Test: Vans RV-4 G-BZPH
- Credit: Keith Wilson
Fast, yet at home on the farm strip, a long-legged tourer that will carry two and a decent holiday’s worth of baggage - and it’s aerobatic too. Can one type really master so many trades?
Words: Bob Davy | Photos: Keith Wilson
The Vans RV-4 has been around for over forty years, having first flown in 1979. Doesn’t feel like it does it! Later models have long since outsold it, but RV-4s are still being built, and around 1,500 kits have been sold. Total annual sales of RV aeroplanes−all models, including kits and factory-built Light Sport Aircraft−exceed the combined total of all the other US light aircraft manufacturers.
G-BZPH, our test aircraft, was built between 1998 and 2001 by a friend of mine, Alex Truman and is now owned by a syndicate at White Waltham. Construction took Alex 2,700 hours in total, whereas later quick-build kits with pre-drilled holes and higher levels of pre-fabrication can be completed in half the time. For this original kit, Alex first had to build the jigs but he says the modern pre-drilled kits are so accurate that the wings and fuselage can be assembled on the floor without jigs, or on your kitchen table, if it’s big enough.
First impressions are how small and pretty an RV-4 is. Like a Pitts Special, it is almost toy-like but don’t be fooled by appearances. ‘RV’ stands for Richard VanGrunsven, the designer who started the business in 1970, and it might also stand for recreational vehicle−this aircraft can fly from short strips, like a Piper Cub, cruise at high speed with fuel consumption similar to a car and perform aerobatics at Sportsman level. It is also great fun to fly. What are the snags? Its light wing loading means the RV-4 is not great in strong winds and it’s not the easiest aircraft to land, but we’ll come back to that.
My first ride in an RV-4 was in the back of G-BZPH with co-owner Mike Collett, when we flew to Belgium on a business trip last year. I have to put my hands up and admit that for the first twenty minutes or so I wanted my mummy. I’m 6ft 2in and a bit of a unit: the rear seat was only just big enough for me, plus when the canopy was lowered it felt as if I was in a glass coffin. For the first time in hundreds of different aircraft, I felt claustrophobic. (I’ve since asked around and it turns out I’m not the only one...)
I grabbed the big A-frame head protector with both hands, told myself to stop being a wuss and after a while the feeling went away. One thing that helped was when Mike explained that, theoretically, if I needed to get out and he was not able to, I could use my left foot to kick the canopy latch open. The feeling of being trapped lessened, even though the only thing that had changed was between my ears−it also helped when he handed me control. I had a little wiggle around, noticing that the stick and rudder were light and powerful, the harmony a perfect one, two, three for aileron, elevator and rudder. And it’s fast! We were knocking along at 160mph for not much fuel.
Here we are one year later and I’m going it alone. Like the pain of childbirth, forgotten when the mother gets to hold the baby, any memories of claustrophobia and being inside a glass coffin are gone now that I am climbing into to the business seat. The front cockpit is snug and sparse, very WWII fighter-like, just the essentials in here and plenty of reminders everywhere that the man who built it is a professional engineer. Most of the bits I like: the fuel gauges for the two 16USgal tanks mounted on the floor, P-51 fashion, with the fuel selector between them; and the aileron trim lever mounted on the stick and working in the correct sense−turn it right for right trim, left for left. Plenty of clever details, some factory-standard, some not. Anything I don’t like? The elevator trim, which looks a bit like a throttle and is mounted right next to that on the left cockpit wall−easy to confuse one with the other and yes: I did, once. Put it down to my stupidity, seeing as one is labelled ‘trim’ and the other, ‘throttle’.
- 4 Flight Test: Vans RV-4 G-BZPH
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This RV-4 has a two-blade, fixed-pitch ‘cruise’ propeller driven by a four-pot 180hp Lycoming but other combinations have been used on these aircraft: three-blade props, six-pot engines with streamline body kits−as if it wasn’t already, the ultimate versions being the razor-backed Harmon Rocket and F1 Rocket, both capable of 200 knots−and reputedly able to have their wings pulled off when flown with two over-zealous, overweight occupants. (Currently the F1 Rocket isn’t approved to fly in the UK and the Harmon Rocket isn’t approved for aerobatics.) A couple of RV-4s have been built with retractable undercarriages albeit the performance gain was modest as the fixed gear is already aerodynamically pure. Unlike later RV designs, there is no ‘A’ model RV-4, the letter denoting a tricycle undercarriage aircraft.
I open the side-hinged canopy with the latch on its forward port side, motor the electric flaps down with the selector to improve access and climb in. Then I have to select the canopy lever open again before lowering it, retracting the horizontal shoot bolts fore and aft and allowing the canopy to seat in the correct position.
Everything falls easily to hand i.e. it’s where it should be, ergonomically. All primary electrical switches are along the base of the panel. To get her going I make a tank selection with the valve on the floor, open the throttle and mixture, switch on the battery and then the fuel pump, while pumping the throttle three times. Then set the throttle half an inch open, mixture rich and turn the key at the far right of the panel. The engine fires into life and I switch on the alternator and radio/intercom. Starting up doesn’t get any easier than this...
There is quite a wait until I see the oil temperature needle come off the stop and then, with stick held back, I open the throttle to begin taxying. Waltham’s grass is notoriously bumpy but the little RV makes light work of it, unlike another friend’s RV-7A which feels like the nose wheel will snap at any moment when moving at anything more than a walking pace. (So much so that he’s just moved it to another, smoother airfield for the summer.)
Today we’re using Runway 11, which is at the opposite end of the field to the clubhouse, but we are there in a jiffy, engine run up and vital actions completed from memory. You shouldn’t need a checklist to fly this kind of aeroplane, maybe just for the emergencies (personally I think you should know all that too−it’s a bit embarrassing trying to do the engine fire drill when the checklist catches fire while you’re reading it). One quirk is that there’s no flap indicator. For a short strip, selecting optimum flap is simply a case of putting an aileron down on the side that you are looking over and motoring the flap down to match it. (Full throw of an aileron is usually pretty much where it provides maximum lift for a given wing, although I’m in for a little surprise with the ailerons on this aircraft−keep reading!) Most RV owners don’t use flap for takeoff if they can help it, because of the low Vf speeds: 110mph for half flap, and 100mph for full flap.
The view outside is excellent and I can see over the nose, just, but I weave anyway because it’s best practice−I get to fly some very high-performance tailwheel aircraft with long noses and don’t want to fall into bad habits. I line up, reminding myself that I will be needing right rudder to counter the engine, and then open the throttle smoothly. The coarse-pitch propeller means that the acceleration isn’t breathtaking for the first few seconds but this little aeroplane soon gathers up her petticoats and starts to sprint, acceleration during the latter half of the takeoff feeling more rapid. Then she goes light on her wheels: a tiny pull on the stick and we are airborne. We climb out at 75mph with the VSI nudging 1,500fpm. More is possible with a climb prop but this aircraft is optimised for cruise and aerobatics rather than short strips and steep climbs−right up my street. I reckon we’ve used 400 metres of runway so still not bad, but nowhere near the figures you see on some websites.
With a decent headset the noise level is low so I take mine off for a couple of seconds to check. Now the noise level is high! So, I put it back on again. Leaving Waltham behind I level off just under the London TMA and accelerate. I have heard some wild claims about RV top-end performance and the reality seems different most of the time. At 2,500rpm the ASI stops winding round at 160mph. Red line is 2,700 so more is available but... well, you just wouldn’t would you? Obviously the TAS could be as much as 180mph at altitude but in the UK I’m never higher than a couple of thousand feet and usually considerably lower, so I think I would be tapping 160 into my SkyDemon aircraft profile.
Fuel consumption is so low it’s better to write it down as mpg than litres per hour (32 if you insist). I worked out that even at 160mph it’s about 22.5mpg, rising to 30mpg if you slow down and lean aggressively. Don’t go too slow though. Alex once flew alongside a Jungmeister all the way from Breighton to Waltham at 100mph and reckons he used almost the same amount of fuel as he would have at 160mph.
In simple terms of cost, RV-4 pilots must have a unique dilemma when travelling from A to B; shall I take the car or the plane? I regularly fly to a private strip near Norwich. If I drive it takes well over two hours, 145 road miles at an average of 25mpg (old Porsche) using nearly six gallons of fuel. By RV-4 from nearby Waltham it would take just over 40 minutes, 110 air miles at an average of 22.5mpg using just under five gallons. Even adding time for to-airfield travel and faff, the RV-4 is still the clear winner. No wonder it is regularly used as a hack by its group to ferry people and parts all over the country, supporting two flying teams.
Today the weather is calm and clear−perfect for RV flying. I have been bounced around like a bean in a tin in various lightly loaded kit planes and microlights, and the RV-4 is no different. One precaution when experiencing turbulence and/or high winds is to slow down to Va, in this case 134mph. The others are to land or not take off in the first place.
Soon enough I am in the manoeuvring area and climb to 4,000ft. I am not wearing a parachute so am reluctant to spin but Alex has assured me that it is a non-event, so I have been persuaded. First, I try a stall. Predictably it takes an age to slow down and I help things along by pulling the nose up. Finally, it gives way at 45mph with a left wing drop. I try another with power and get 42mph, same wing drop−I don’t know if he is joking but Alex thinks the left wing might have been bolted on with a tadge higher incidence than the right. Next I do the same again and boot on left rudder, just above the stall speed. She flicks into a spin nicely and stops in one turn with opposite rudder and just a relaxing of back pressure. All in all, it feels very safe.
A word here; max aerobatic weight is 1,375lb and empty weight of a very basic RV-4 is published as 933 (some over-equipped mini-airliner RVs being much, much heavier) so there’s only a maximum of 442lb available for extra equipment, pilots, fuel and bags. Leave out the autopilot, extra cushions and furry dice! Non-aero max weight is 1,550lb giving a much more useful 617lb and you can start thinking about what to carry in that big, 100lb capacity tub behind the rear seat.
Aeros then: I start with a loop, diving to 160mph (but normally you can go in at straight and level) and then pulling gently at first, introducing full throttle on the way up (fixed-pitch prop, remember) a bit of right rudder as I slow down over the top and then pull back the power down the other side. I am using three of the +6/-3g available (these being absolute minimum g limits currently accepted by the LAA for an aerobatic aircraft−quite right too) and I under-pull, the loop making more of an I rather than an O. I have probably been reading too much about heavy Americans clapping wings, so I do the next one at 4g and it goes much better. Ultimate design load is 9g for three seconds after which, if the aircraft makes it back to the airfield, it will be scrap. But it probably won’t (make it back to the airfield, I mean).
I’m well inside the limits as I carry on with a big, lazy barrel roll, the coarse-pitch prop making things much easier than the last fixed-pitch aeroplane I did aeros in; the Chipmunk. That was a relentless battle not to overspeed the motor. I calculate the RV’s roll rate to be around 150 degrees per second−nothing startling but more than enough for polite aerobatics. (Later I asked around my competition aerobatics friends and the consensus was that a decent pilot could fly at Sportsman level in an RV-4, not higher because you can’t flick it.)
Something odd happens when I try the first aileron roll. I pull up at 150mph until my toes are on the horizon, check the stick to neutral and then put in full aileron. The stick starts to chatter as we go inverted, telling me the down-going aileron is stalling. I still get round okay, and on the second one I slow the stick movement and push forward very slightly as I invert, which completely stops the chattering. Not unsafe but quirky. I wonder if optimal flap for takeoff might be a few degrees less than the angle of max aileron deflection? An interesting experiment to conduct on a lazy day at a nice airstrip with someone at hand on the ground to mark the takeoff points.
After a few more manoeuvres linked together, I can’t think of anything else to do with the aircraft and as we already have the air-to-air pics in the can from a previous flight, it’s time to head for home. I put the nose down and let the speed creep up towards the 210mph Vne, pulling the throttle back progressively to keep under the 2,700rpm maximum. Air noise builds but that’s it, the controls are still light. This is why the RV-4 is easy to overstress. A bit of red mist at the airshow and next thing is you are landing with more dihedral than you took off with−or not landing at all.
Predictably, losing energy in the circuit is difficult. Shock-cooling would be easy for the unwary. I pull back to a nominal 1,500rpm with carb heat applied, ending up on base leg before I have the speed back to 110mph for the first half stage of flap, which is done by eye of course. I visualise what full aileron looked like and go half way, followed by the last bit as I turn final at 100mph. 1.3 times the demonstrated Vs of 45mph is 60, so I approach at 65, backing off to 60mph over the hedge. Now I am looking at the end of the strip, conscious that the grass needs to be three feet from my backside at touchdown. Throttle closed and she floats for a second or two then wheels on, a couple of inches of forward stick keeping the tail away from the ground. Then the airfield takes over, thumping and bumping at me until we are at taxi speed.
Hard to land? I didn’t think so but the wind was down the runway, it’s grass and 1,000 yards long, plus I have tons of tailwheel time−so I ask around afterwards. The consensus seems to be that the RV-4 will bite you if you let it−especially on concrete−and scores between seven and eight out of ten on the Pitts-Special-Difficult-To-Land Scale, where the Pitts is ten. Landing roll was 300m: again, much more than I have seen on websites.
Do I want one? RVs have now firmly replaced thirsty Yaks as most numerous ‘exotic’ aircraft at many airfields and I can see why. The friends I fly with own the following aircraft types, in shares or outright: Cap 232, Cessna 180, Extra 300, Extra 330, Harvard, Hurricane, Malibu turboprop, Nanchang CJ-6, Pilatus PC-9, Piper Cub, Pitts S-1T, Pitts S-2A, RV-4, RV-7, RV-7A, RV-8, Yak-3, Yak-18T and a Yak-52. So quite a wide selection, apart from the small herd of RV elephants in the room.
Last year a few of us flew one leg of a weekend away all together at the same speed. From memory, when we arrived at the pumps an hour later the Hurricane filled up with 180 litres, the Harvard needed 130, the CJ-6 required nearly ninety and the RV-4 used less than forty.
One thing we agree on is that eventually we’ll all end up selling everything else and have an RV-something. Ideally, I would go for a slightly bigger RV-8, or maybe a Harmon Rocket if aerobatics are ever allowed in the UK−you won’t find me sitting in the back of it, though!
Wing area 10.1 sq m
Weights & leadings
Empty weight 424kg
Useful load 280kg
Fuel capacity 32 us gal (30 useable)
Stall speed 54mph
With flap 51mph
Rate of climb 1900fpm
Take off run 197m
Landing run 152m
G limits +6/-3
Engine & prop
Lycoming O-360 180hp @ 2700rpm
Metal fixed-pitch prop