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Super 8

flyindoorman

Well Known Member
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
 
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 :eek:
 
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.
 
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.
 
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.
 
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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
 
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The air, or drag, does not feel the larger engine. Thus the drag of a super 8 or rocket will be the same as a comparable RV. Over the years I have flown in cross country formation with all sorts of RVs. When we fuel up I always take less fuel then the RVs.
It is not really a mystery, the RV guys usually feel bad about holding me back and they run a bit harder then normal. I encourage this :), my plane is throttled way back I can run much leaner, thus the lower fuel burn. Comparing fuel receipts is always an eye opener.
 
Are you flying an F1 Rocket in your example above? Thanks.

And as far as crosswind operations, how does the F1 feel and perform compared to a middle of the road RV-8? I often wondered if an HR or an F1 would be my preference but in my current search for the right RV-8 for me, a large part of my mission entails cross country work to and from a high desert / mountain area with often a lot of squirrely winds - and some of those landings will be after dark... In every other way I love the idea of an HR or an F1 as much as an RV8 and in some ways more so.
 
Here is where you can get some more info on the Super 8.

http://mstewart.net/super8/faq.htm

Having flown a Super 8 solo, I can say the power is great and it flys like a heavy RV. I have flown my RV-6 at 1,800 pound gross and use the way it flys when heavy as a heavy RV reference.
 
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My comments above were mainly about my F1 with the EVO tapered wing but I saw the same fuel results with standard wing as well. On average the standard F1 is 2 to 3 knots faster then a comparable HRII. The only real difference, from a drag perspective, is that the lower firewall is wider on a F1 then a HRII and I believe it improves drag slightly.
As for crosswinds the larger engine tends to make the airplane more stable in crosswinds. I have tackled some pretty nasty crosswinds when travelling. I would not recommend exploring the crosswind capability until you have quite a few hours in the plane, the same as for any new aircraft.
 
I have enjoyed reading this thread. As the one gentleman commented, the configuration that best addresses your type of flying is the one to go for.
Interestingly, the builder of my plane customised the RV8 with the 540, flat wrap windshield amongst the modifications and the aircraft he built that won grand champion in 2017 was a customised Rocket with a 4 cylinder and Rv8 wings.
As Dan mentioned, my RV8 is heavy. A contributing factor is the show quality paint. The wings and fuselage have had the rivets covered with highbuild.
Tom Martin we have met in Welland where I ?m based. Also, I was in a 3 ship formation with 2 T28?s that you chased down after takeoff from Tillsonburg a few years back.
A gentleman asked if he could photograph my plane when I flew out for a hundred dollar hamburger this past summer. I see he?s posted some photos on the web. If interested goggle c-facm rv8.
 
Thanks

Thanks for all the feedback I'm looking for a fun to fly traveling aircraft. I do not participate in aerobatics so I will remain sunny side up. I have previously owned a 200hp RV8 that I sold a few years ago.
 
Just my .02 but I've seen a few Weight and Balances on 4 and 6 cylinder RV's
In some cases some very creative ways to deal with the added weight of the 6 cylinder....
Everything from...its safer with a more fwd CG, just have to land with power to flare..
To large concrete blocks, red toolboxes and bags of fertilizer zip tied in the tail
Take care
Mike
 
No time in a "Super"-8, but plenty of time in a 200 -8 and a 260 Rocket, so take the following as you see fit:

IMHO, the VNE limits and adding ballast to the tail are significant downsides to the -8 airframe. The Rocket is a much better choice here - no need to add lead in the tail and it's a significantly stronger airframe.

Beyond the above, the biggest difference as a "travelling machine" is the cockpit ergonomics - for me the Rocket is far superior to the -8. Its personal choice, but make sure you get some time in both (with the canopy closed) so you can compare for yourself. The -8's front baggage is very handy if you really want to load it up though.

I'm also happy to confirm that the Rocket matches or even beats the cruise fuel economy of 4 banger RV's when flown head to head... Not sure how the Super -8 fits in that mix though.
 
Insurance costs..

The other thing to consider is insurance costs, which I understand to be significantly higher for the 6 cylinder machines.

Perhaps someone could give some comparisons for us dreamers..
 
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

I've got a lot of time in my Super 8 and wholeheartedly would say go for it. I routinely call mine a "poor man's P-51" for good reason. Their performance is spectacular!! I can throttle back and fly formation with a 4 cylinder RV and be within 1 or 2 tenths of an hour of the fuel burn that they have, because we are using approximately the same horsepower. In short they are a hoot to fly, have tons of power when you want it, and can run off and leave your 4 cylinder buddies when it's time to fly home:).
 
Insurance

The other thing to consider is insurance costs, which I understand to be significantly higher for the 6 cylinder machines.

Perhaps someone could give some comparisons for us dreamers..

My quote was only about $240 more than a standard RV8. Total about $1,700
 
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