Super 8

[flyindoorman]

I'm looking at a Super 8 and wanted to get feedback from those with experience in such. I really like the performance and am wondering if there are any gotchas outside of watching VNE

[Walt]

No experience flying one, and I'm sure it fun, but I think every "super" I've worked on has had a prop strike.
I almost had one doing a prop balance on one

[crwrpmr]

I purchased my IO540c4b5 powered RV8 in 2004 from the builder who recently won grand champion kit built at Oshkosh. He was a previous Oshkosh winner with warbirds and he told me the RV8 I purchased was built to be a champion. The aircraft is impressive for workmanship and performance.
The aircraft has 340 hours on the tach now, I have flown it 220 hours. The reason for the low hours is because I work in Asia and the aircraft is based in Canada. It gets flown 6 weeks a year.
This is the only RV I have flown and indeed flown in, so my comments have no basis of comparison.
Obviously, CofG had to addressed in the build. The battery is located in the rear of the fuselage and there is lead in the horizontal stabilizer mounting area. When flown solo, the builder had 4, 4 quart oil containers filled with sand on the upper shelf of the rear luggage area. I also use that ballast when flying solo (I'm 145 pounds in weight). Empty weight of the aircraft is 1265 pounds.
My approach speed is 80MPH and the trim has reached the stop at that speed. I do wheel landings and carry power until the mains have touched the ground.
Top speed at 9500 feet is just over 200 knots and at that altitude it cruises at 180 knots on 11.5 usg rich of peak.
On a smooth day I once left takeoff power to see what speed it would do at 2000 feet. It reached VNE and maybe would have gave more but I pulled the power back.
I took a video of the instruments while cruising at 6500 feet this summer. Reviewing the video the instruments show:
176 mph indicated, 11.5 usg fuel flow, 2200 rpm, 20 manifold pressure, the engine oil is almost always 170 degrees and pressure 75 psi.
My engine vents a bit of oil that I clean from the belly after each flight. My research shows this is not uncommon for the IO540. I add a quart every 8 hours to keep the quantity at 8 quarts in the engine.
I flew the CF 104 for 6 years and the CF 18 for 3 and this RV8 puts the same smile on my face those two fighters did.
The aircraft has the performance to fly formation with a pair of T28's my friends fly.
Your question "are there any Gotchas", Yes, your correct to be concerned about exceeding VNE. The aircraft is extremely slippery and will accelerate fast when pointed down hill with power on.
My aircraft has no undesirable flight characteristics, it is a joy to fly.
Hope this helps.

[rv7charlie]

I assume that there's no possibility of acro, right?

[DanH]

The 540 giveth, and the 540 taketh away.

Flown solo, -8 stick force becomes heavier and heavier as the CG moves forward. An angle valve (IO360 or 390) with a metal prop is not as fun for solo yank and bank as the 360 parallel valve and light prop combinations. I have not flown a 540-powered -8, but the trend is clear. Trimmed for 150 knots, a pitch pull to 3.5G is likely to be quite heavy, just like the angle valve fours. It's one of the few things I don't like about my current ride.

Above, Rob is reporting an empty weight roughly 100 lbs more than average. The extra mass is engine and lead in the tail, so it will have a higher polar moment of inertia for the same weight and CG. That slows velocity change in pitch and yaw, most notably spin recovery.

If we assume equal loaded weight, steady state climb with the 540 will be superior. It's the thing HP does best. Super-8 climb should be a real hoot on a cold day.

Cruise performance is best compared using a speed vs fuel flow metric. I would expect a Super 8 to be worse than any four-cylinder version when flying a typical solo cross country, a function of wing loading. RV's are slower when loaded.

Super 8 top speed should be higher, although not by a lot as compared to the big bore fours. Again it would exhibit higher drag due to loading, plus the power squared rule applies.

The angle valve fours and the 540 both result in stable haulers. It's the plus side of the forward CG trade; they fly nice with the rear seat and baggage full. However, apples to apples the Super 8 would be payload limited to around 100 less lbs. Listing a 2000 lb gross weight on the paperwork doesn't change the spar.

The 540 costs more to buy and maintain, although an owner can probably recover the purchase difference at sale time.

Quick comparison. Flown solo, my 390 fastback will exceed VNE down low (best recorded was 206 KTAS), and get close at 8000. At 11.5 GPH and 6500, it will push 190 KTAS (218 mph). After some tweaking, the typical 8~10K cruise is currently 182 KTAS (209 mph) on roughly 9.1 GPH. Empty weight is 1167 with a metal Hartzell. There are no speed mods other than cooling drag reduction, the fastback, and wheel pant boots. The 390 is internally stock.

What follows is pure opinion, based on the above. I'd recommend a Rocket if going fast is the primary goal, an angle valve 8 for a hauler mission, and a 180 HP parallel valve 8 for a fun machine. In a hard comparison, I don't think a Super 8 offers enough extra to be worth the compromises.

[Carl Froehlich]

+1 on Dan?s comments.

Carl

[Mike S]

Rob, welcome aboard the good ship VAF

[Mike S]

Originally Posted by rv7charlie

I assume that there's no possibility of acro, right?

Ever heard of Team Aerodynamix?? http://www.teamaerodynamix.com/planes.html

Lead plane is a super 8

[rocketbob]

I've flown John Marshall's (RIP) Super 8 a few times. I've also flown a 200hp RV-8 a few times as well. My choice would be the 540.

I never noticed any unpleasant handling characteristics or heaviness. Probably its because I was too busy smiling climbing out a ridiculous angle.

Super 8 lands a bit easier than a Rocket.

I've been on many cross-countries with a friend in his F1 and we would always compare fuel receipts. Always beat me by a few tenths of a gallon.

[Robert Anglin]

Dan has some good numbers above and is right on the money. We put together an 8 with P-valve IO-360 with 9:1 CR and a Prince P-tip carbon prop for what is one of the most all round formats in use for an RV-8. At 1008 Lbs. empty it is very strong with 195 Hp. and can hall 792 Lbs. use-full into the air and not get outside the recommended G.W. One of the hints you have made is to do Acro. The lighter an 8 is and the more balanced an 8 is, the more responsive it is. The statement Dan makes with respect to an angle Valve 360 with a constant speed prop, is a good point we have found it to be one that many others have noticed about their 8's and Acro work. With the big 6 on the nose it will be a compounded amount to that of the A. V. 360 with the C.S. prop. It boils down to what you like to do when you will be flying. Bothe the Super 8 and the Rocket will fit their roll and it may be what you want or need to satisfy your needs. The 8 can be an all-round platform if that is what you want. Just our two pennies. Yours, R.E. A. III # 80888