mkjprice

mkjprice

Active Member
I am still a newbie here, and I have pretty much decided on building an 8/8A. I was just watching on youtube some videos about a Super 8 and a Harmon Rocket. I realize the climb rate, and the speed is faster, but it also has higher empty weight and increased fuel burn.

Now for the sticky question. Is it worth it to build a Rocket/Super 8 over a standard 8? I know a lot of this comes down to what your mission specifics are, but is the increased weight, horsepower, climb performance, and fuel burn worth the extra expense or would it be better to put a higher performance 360/390 in an 8.

I don't want to see a whole lot of arguing, but I would love to hear what different opinions are out there. I also realize that it will likely be next week before I get a lot of responses since many on the board are in Osh this week.:( Wish I was there too!

Thanks in advance.
 
mkjprice said:
Now for the sticky question. Is it worth it to build a Rocket/Super 8 over a standard 8? I know a lot of this comes down to what your mission specifics are, but is the increased weight, horsepower, climb performance, and fuel burn worth the extra expense or would it be better to put a higher performance 360/390 in an 8.
Thanks in advance.
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Your question is not answerable. "Worth" is in the eye of the beholder. You can get 100 people to say no, and a hundred to say yes. It means nothing. Bout all you can do is look at the performance, cost, and other factors that are readily available and decide for your self. Id suggest a facts based approach. We have no way here to put any weight on the factors for you. You have to weigh them yourself.

If you have some fact based questions that dont seem to be answered in other places, bring them on and we will try and sort out the fact from fiction.
Happy to help.
 
May I suggest that you:
1) Make a list of the reasons/features why you are choosing an 8/8a
2) Put the list in prioritized order
3) Take a shot at evaluating which of these a Rocket 8 would enhance over a standard 8.
4) Ask the same questions here of the experts to get their input as to whether it ould work out as you expect, or there are tradeoffs that you are not seeing.

Tim
 
Fuel burn.

Mike, is it not true that you can cruise alongside an IO-360 equipped -8 and flow the same fuel, throttled back to his speed?

Thanks,
 
WOW!

I didn't mean to start and argument - My question roots about what is the best performance bang for the buck? I saw Kahuna's video on youtube and that is what got me thinking about it. He had a 6 now has a super 8, and that is what got me thinking.

From what I can figure it is about 20K more to build a super 8 vs a standard 8. I agree, more power is always better (especially when field elevation is around 5000'), but at what cost.

Also from what I can gather, there are still airframe limitations that limit the use of the full power capabilities of the larger engine. Does Vne change in a super 8. In the Evo Rocket it seems to.

Again by no means did I want to start an argument, and in no way do I want to say one is better than the other, I was simply trying to start a discussion of the pros and cons from different perspectives between the different aircraft.
 
mkjprice said:
I was simply trying to start a discussion of the pros and cons from different perspectives between the different aircraft.
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Suggest you search, advanced search, title only, super 8.
All perspectives have been covered in lots of threads over the years.
 
Great welcoming environment here huh?

Welcome to VAF... beware the opinion based questions - you'll get more than you want every time.

Install a 600Hp gas turbine and call it a Super-Duper-8 then put a wood prop on the front and see what you get :)

Whatever YOU build and fly will be what YOU think is best anyway!

Once you wade through the chaff, VAF is an invaluable resource.

Good Luck!
 
pierre smith said:
Mike, is it not true that you can cruise alongside an IO-360 equipped -8 and flow the same fuel, throttled back to his speed?

Thanks,
Click to expand...

No.
The primary factor is compression.
A higher compression engine than mine will generally do better.
All other things being equal, of course they never are, and the only difference being 4 or 6 cylinders, I will typically do better for reasons of reduced efficiency of air flow through the engine at high MP settings. Restated. At a given airspeed, my MP is much lower. The 4 cyclinder higher. Higher MP settings result in more turbulent air flow through the engine and therefore slightly less efficient. At least that is how it has been explained to me.
What we see from lots of field testing across a lot of cross country flying with a spread over many different RV's, is that the higher compression engines do better, the same compression does slightly worse. The difference is so slight its really not worth mentioning. +-.5gallon over a 35 gallon flight.
 
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This is serious!

RV8R999 said:
Great welcoming environment here huh?

Welcome to VAF... beware the opinion based questions - you'll get more than you want every time.

Install a 600Hp gas turbine and call it a Super-Duper-8 then put a wood prop on the front and see what you get :)

Whatever YOU build and fly will be what YOU think is best anyway!

Once you wade through the chaff, VAF is an invaluable resource.

Good Luck!
Click to expand...

This is a very good point.

You need to be aware however that there is a an FAA ruling on the word super and in fact the word Duper.

Super must only be used when you reach at least 250 hp in the front and you need to exceed 350hp to use the word duper.

With 600hp legislation has been passed to allow the word Mega to be added.

So your permitted to build a Mega-Super-Dupper-8.

If you paint it red or chrome the exhausts, that is a whole new level and that needs additional bling certification.
 
GusBiz said:
This is a very good point.

You need to be aware however that there is a an FAA ruling on the word super and in fact the word Duper.

Super must only be used when you reach at least 250 hp in the front and you need to exceed 350hp to use the word duper.

With 600hp legislation has been passed to allow the word Mega to be added.

So your permitted to build a Mega-Super-Dupper-8.

If you paint it red or chrome the exhausts, that is a whole new level and that needs additional bling certification.
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The only thing I don't like about getting the bling cert are the quarterly inspections. "If it don't shine, it ain't mine" type stuff gets old.. ;)
 
Been There - Done That

Build a quick build -8 and you will be money, time and frustration ahead. I built a Harmon Rocket II 10 years ago (S/N 002), and I can tell you there is a considerable difference in the amount of work the builder needs to do to finish this aircraft as opposed to using Van's QB kits with matched hole drilling. If you haven't built an old style kit before, i.e. -3, -4, or early -6, you probably shouldn't tackle the Rocket as your maiden build - you may get mired down to the point of giving up. There are a lot of beautiful, great performing -8's out there, but only a 150 or so Rockets (not counting F1's) - there is a reason for that. Build a QB -8. Just MHO.
 
Have you checked

On insurance quotes yet.

I think that's important. 8's seem to be about half the price. A couple grand a years savings on insurance buys a lot of gas. Almost as much as Kahuna saves flying next to us little motored 8's.
 
Awesome!

That is part of what I was wondering is how much harder it is to build, insurance is a good point too. So what I can gather is that a Rocket is just that - a rocket, and is worth the trouble and the extra work to build it if your mission requires it. Also what I gather that the -8 is no slouch on its own, and is great as it and would likely be better for the first time builder.

Thanks for the comments. You know as you start the process of getting information to build, making decisions, I am getting more options than my little brain can handle.

I plan on makeing a trip to see Van's in the early spring next year and bring my first kits home with me.

I love this board.

Thanks,

Mike
 
Do this, Mike

Plug in some numbers...in my case, 900 miles to Osh. By Rocket @ 230 MPH...3.9 hours. 15 GPH ROP = 58.5 gallons..(what my -10 burns ROP). $292.50

At 200 MPH in an -8...4.5 hours 10 GPH ROP = 45 gallons..$225, $67.50 savings, or 36 minutes extra time.

They can both be run LOP, my -10 at 11.5 GPH and the -8 probably 7.5 but I give up 11 MPH running LOP. These more or less approximate reality, since I've owned both engines.

I rode in Bob Mill's Super -6 a couple of years ago and man, acceleration to die for!..that and 3,000 + FPM climbs!

The -8 will comfortably do 2,000 FPM and ain't no slouch, outrunning Bonanzas, 210's and Comanches and the older Cirrus.

Best,
 
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I'd like to correct just a couple of assumptions posted that I don't think are quite accurate. In terms of cost, the primary difference is going to be the cost of the engine. A -4 kit (which the harmon is based) is less than a -8 kit but the engine is more. If you can get a good deal on an IO-540 somewhere, they can be built for about the same price. If you buy new, the 540 is about $15K - $20K more. Ouch. (When I built my Rocket, a 540 was actually LESS than a O-360. Then the RV-10 came along and........)

If building is a concern, most definiely build the -8. No comparison.

In terms of efficiency, they both use about the same fuel for the same performance as Kahuna said. The Rocket will fly cheap if you want to but it will also go fast when you need (want) to.

Insurance is a good item to consider and the Rocket will cost you more as others have pointed out.

I know Mark is taking deposits for the new F1 EVO. It will probably cost you more than a -8 by about $40K but carbon fibre wings and a retract option. You don't need one, but you will probably WANT one. My F1 was the finest aiplane I've ever owned.
 
Thanks

Randy,

Thanks for the comments. Your comments are what I was looking for when I started the thread.

Mike
 
Me too

I went through the same thought process. I like the looks of the -4, love the Rockets, thought about a super -8 and of course a straight -8. In the end I built the -8. I haven't flown, but no regrets thus far. The build was hard enough for me that I'm glad I didn't do the Rocket or the -4 (I'm a 1st time builder).
Good luck on your decision!
 
f1rocket said:
I'd like to correct just a couple of assumptions posted that I don't think are quite accurate. In terms of cost, the primary difference is going to be the cost of the engine. A -4 kit (which the harmon is based) is less than a -8 kit but the engine is more. If you can get a good deal on an IO-540 somewhere, they can be built for about the same price. If you buy new, the 540 is about $15K - $20K more. Ouch. (When I built my Rocket, a 540 was actually LESS than a O-360. Then the RV-10 came along and........)

If building is a concern, most definiely build the -8. No comparison.

In terms of efficiency, they both use about the same fuel for the same performance as Kahuna said. The Rocket will fly cheap if you want to but it will also go fast when you need (want) to.

Insurance is a good item to consider and the Rocket will cost you more as others have pointed out.

I know Mark is taking deposits for the new F1 EVO. It will probably cost you more than a -8 by about $40K but carbon fibre wings and a retract option. You don't need one, but you will probably WANT one. My F1 was the finest aiplane I've ever owned.
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Did you sell it out of wanting another aircraft or simply for other reasons ie wanted the funds to invest in something else in life.

Your rocket is just one of the best looking planes I have ever seen. I was surprised to realised you don't won it any more.
 
GusBiz said:
Did you sell it out of wanting another aircraft or simply for other reasons ie wanted the funds to invest in something else in life.

Your rocket is just one of the best looking planes I have ever seen. I was surprised to realised you don't won it any more.
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Thank you for the compliment. I appreciate it.

Personal reasons. I'm at a different stage of life right now. The right offer came along at the right time. It wasn't even for sale at the time. I guess it was Karma.

I still love that airplane and as I said, there's no better or different airplane I would own. I have business trip planned in October to its new home. I plan to stop by and take a look at it and talk to the owner.
 
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One other item to consider is comfort.

I had my F1 for almost 5 years and like Randy I think it was the finest plane I ever owned but at age 60, sitting for hours with my feet at or above the level of my butt was taking a toll.

At 2 hrs the backache became almost unbearable and at the end of every flight getting out and climbing down was misery.

I still occasionally fly a friends RV 8 and find it quite comfortable. If you are older and tall this is a significant consideration.
 
mkjprice said:
My question roots about what is the best performance bang for the buck?
Click to expand...

That one as a standalone question has a pretty simple answer.

The most performance bang for the buck value, in my humble opinion, is a plain RV-8, with a parallel valve 360 and CS prop. Build it light and keep it simple and you'll have excellent performance value without having to pour a metric ton of money into it. And it'll still go plenty fast. ;)
 
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I am also an ex- F1 Rocket owner, now RV-8 owner.

Needs and desires and requirements change. The RV-8 suits me at this point in my life.

My definition of "performance" might be different from yours. Climb, stall speed, fuel burn, sexy, etc.

As Mike and others stated there is a ton of information on this site to be enjoyed and filtered.
 
Not exactly

Pierre wrote:
"Plug in some numbers...in my case, 900 miles to Osh. By Rocket @ 230 MPH...3.9 hours. 15 GPH ROP = 58.5 gallons..(what my -10 burns ROP). $292.50

At 200 MPH in an -8...4.5 hours 10 GPH ROP = 45 gallons..$225, $67.50 savings, or 36 minutes extra time."

Where in the heck did you get those numbers, Pierre?:confused:

Most Rockets will do 230MPH on 11GPH (175KIAS @ 8000MSL). Test data on a couple others reveals they will do that same speed on 9.5GPH (@ 17500MSL), but you will be breathing O2.

If we re-work the equation above using real Rocket fuel burn numbers, the cost falls to $214.50, disregarding the climb, as is done above. So, it appears the Big Motored Beast you can save $10 AND 36 minutes.

Most Rocket drivers would have made that trip to OSH at the higher altitude (we get there kinda quick), so please use the higher altitude numbers in your comparison equation.

So, in fact, you are comparing a plane that does 200MPH on 10GPH with a plane that does 230MPH, either @ 11GPH (+1GPH/+30MPH) at the same altitude, or @ 9.5GPH (-.5GPH/+30MPH) higher?

The RV8 would be indicating ~150KT to give a 200MPH GS @8000MSL, and my F1 will indicate 145KT @ 7.5GPH. I would guess ~8GPH @ 150KIAS? Does the 8 really need 10GPH to hit 150KIAS @ 8000MSL? I'll bet it's closer to 8, which throws the whole efficiency discussion off just a tiny bit....

In the end analysis, it depends on your mission profile. One type will fit better then the other, especially if your profile includes a requirement for unbelievable deck angles on departure.:eek:

I'll bet the Uber 8 gives numbers close to the Rocket numbers, especially above 8000'MSL. I was able to swap rides with Kahuna, and his plane is a sweet machine indeed.

BTW in terms of build complexity, the HR2 and the F1 are not in the same class; the F1 is a QB kit.

Any doubters are welcome to a fly off.:cool:

Carry on!
Mark
 
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