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Thoughts on turbocharged Rockets?

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DesertFlier

Member
I'm still very much in the dreaming stages of an aircraft project. The aircraft I really want is a Harmon Rocket II.

Here's my thinking:

I want cruise speeds as high as possible with fuel flows as low as possible (who doesn't?). We know the HR2 is redlined at 275 mph TAS. We can't go faster than that, but can we be more efficient?

You can pick up bits of efficiency here and there. You can use GAMI injectors and an engine analyzer to run lean of peak, lowering fuel flows. You can use electronic ignition to squeeze more power out of the engine by optimizing the timing. By carefully designing the cowling and cooling system, you can minimize drag there.

What I'd really like to build is a turbocharged Rocket. You can't fly faster than 275, but you can fly higher in the thinner air and, in theory at least, burn less fuel doing it.

So, are there any turbocharged HR2s out there, or is anyone working on a similar aircraft? Keep in mind I'm already aware of the disadvantages of cost and increased maintenance. I'm just curious to see what others with more experience might think of this idea.
 
Welcome to VAF!!!!

Paul, welcome to VAF:D

Turbo'ed Rocket--------I like the way you think.

Good to have you here, enjoy the site.
 
Wolfgang Meyn built a supercharged F1 Evo. I believe it was a Vortec Supercharger. N104RX. I think he sold it, but I can't remember who has it now.
 
Sure thing!!!

Thats what I am doing on mine, I want as many ponies as possible when needed.
TIO-540, nuff said.....

When I started racing cars I was told one thing by a great racer that was instructing me in order to get my profesional credentials, and that was:
"Always make sure you have more horsepower available to get you out of trouble than the horsepower you used to get you in to that trouble"
 
Thanks for all the greetings, folks!

I can't wait to get started on this. I've got the place to build it and I've got approval from my wife. I need to gather some tools and the plans and then I'll order the empennage kit.

My questions on the turbo:

How high do you need to go to benefit from turbocharging? Since the airframe is redlined at 275, we can use that as the one constant in a sea of variables. As you go higher and higher, the air gets thinner and you should need less and less power to get to 275.

However, there has to be a limit to this logic. My estimation is that at some point, the HR2's wing will be the limit. As you increase altitude, form drag decreases, yet so does lift. You have to keep increasing alpha to carry the same weight. At some point you'll reach the wing's optimum AoA, after which any increase in alpha will give you more drag than lift. But where does this happen? Hard to say, really.

Or...

The limit might be in the oxygen system. As I understand it, supplemental oxygen of the compressed gas type (as opposed to LOx) is only good to about 24,000 feet. After that it takes too much physical exertion to breathe and you'll start to suffer hypoxia. This might happen before you ever reach the aircraft's potential altitude.

Do you suppose it's better to turbo-normalize an engine or boost the heck out of it? With turbo-normalizing you're limited to approximately 300 horses. With boosting you can go much higher, with reduced engine life. The HR2 is already high on power-loading, even with a 260hp engine. I don't know if it's necessary to squeeze every last pony out of the engine. I'd just like to maintain that power up high.
 
DesertFlier said:
Thanks for all the greetings, folks!

However, there has to be a limit to this logic. My estimation is that at some point, the HR2's wing will be the limit. As you increase altitude, form drag decreases, yet so does lift. You have to keep increasing alpha to carry the same weight. At some point you'll reach the wing's optimum AoA, after which any increase in alpha will give you more drag than lift. But where does this happen? Hard to say, really.

Or...
Click to expand...

"Or.." includes several potential gotchas including:

Mach tuck.

Flutter.
 
My best guess

Some practical limits I can think of, in no particular order:

1) Decreasing true airspeed redline with altitude. Redline speed is actually a function of Mach number, not TAS. This doesn't really matter at 8000, but it's a big consideration at 25000.

2) RSVM. ATC stacks aircraft closer together at high altitudes based on special certification requirements usually only achievable by jets. Without RSVM capability, you'll have limited access to altitudes above 24,000. Of course, unless you're IFR, you won't be flying above 17,500 anyway.

3) Engine efficiency. Even with a well-engineered turbocharger, the engine will most likely reach it's critical altitude in the high teens. Going higher will cost you time and/or fuel, unless you can find favorable tailwinds. At the end of the day, turbos usually fly in the mid to high teens unless weather forces them higher.

4) O2 practicalities. Oxygen systems get complicated (and very critical) at altitudes above 16,000 feet or so. The cannula can't get the job done up there, so you really need a pressure mask.

All that said, I love the idea. Due to thermal stress issues, turbos gemerally relegate aircraft engines to travel use (no aerobatics or short hops), but a turbocharged rocket would be hard to beat for xc travel by anything but a $2M turboprop aircraft.
 
No problem to get a ton of power out of a properly built IO-540 with turbocharging. You probably don't need to exceed 30 inches to get your 275 mph at say 18,000 feet where you're still ok with the cannula. With modern turbos, the engine's critical altitude will likely be higher than your's or the Rocket's, we can jam out PRs of 4 to 1.

Aerobatics and short hops no problem. With a proper turbo and intercooler setup and proper oil cooler, thermal issues should not be a big deal but you may pay with fuel flows if you want to go fast all the time. A mask is ok to 25,000 or so but ATC won't want you above there anyway. Above 25K you need a pressure mask which is not much fun.

It can be done and it would be a cool project.:):cool:
 
Standard wing rockets are limited by their wings when it comes to higher speeds. As you get above 250 mph added power brings an ever decreasing speed increase. It gets worse the higher you climb. This is the main reason that Mark Fredrick came out with the EVO wing and it has proven itself at both higher speeds and higher altitudes.
There is also a c of g consideration with the standard wing rocket in that you really do not want to add too much more weight to the nose.
My recommendation would be to build it as a stock set up and if in a year or so you really do want to explore altitudes add the turbo at that time. You are going to build the plane and so you have every right to modify it.
 
DesertFlier said:
Thanks for all the greetings, folks!

I can't wait to get started on this. I've got the place to build it and I've got approval from my wife. I need to gather some tools and the plans and then I'll order the empennage kit.

My questions on the turbo...
Click to expand...

Hi,

I'd also STRONGLY recommend you get involved with
http://www.homebuiltairplanes.com/forums/aircraft-design-aerodynamics-new-technology/
and ask your questions there. There are some VERY talented aircraft designers there who love to discuss this type of thing. Don't turn your back on VAF, but if you want to start thinking outside the box, the Homebuilt forum is the place to do it. It's like having your own personal aeronautical engineering staff on retainer.
 
Tom Martin said:
Standard wing rockets are limited by their wings when it comes to higher speeds. As you get above 250 mph added power brings an ever decreasing speed increase. It gets worse the higher you climb. This is the main reason that Mark Fredrick came out with the EVO wing...
Click to expand...

Care to elaborate on that? Where does the standard HR2 wing fall short, and why? How is the EVO wing different?
 
Paul...

,,as the air gets thinner, the lack of wingspan makes the airplane start "mushing", if you will....fly at increasing angles of attack.

Look at a glider's very long wings....most of a wing's lift is produced toward the forward third and RV's just don't have much area there....the exception being the -9 and -10.

Best,
 
Pierre, increased angles of attack are what I'm looking for actually, to a point. I don't have any personal experience with the HR2, but this is how I understand wing operation for airplanes in general:

The wing is at its highest angle of attack at slow speeds during takeoff and landing, when the aircraft is closest to stalling. This isn't the most efficient, but it's creating enough lift to hold the aircraft up, and enough drag to help slow it down.

At the opposite end, when the aircraft is in cruise, the angle of attack is at its lowest. Induced drag is still the same (you're still lifting the same weight), but the wing is at less than its optimum angle of attack (not an optimum lift-to-drag ratio), and form drag predominates.

But, if you climb up higher, you do have to increase alpha to hold up the same weight, because the air is less dense. At some point, you will reach the wing's optimum alpha and thus its maximum lift-to-drag ratio. At this point it will take a minimum amount of thrust to overcome the sum of all the drag forces on the aircraft.

Which brings me back to my original question: At what altitude does the stock HR2 wing reach its optimum angle of attack at gross weight? I realize the HR2 has stubby constant-chord wings, but there's still going to be a point where they are at their best, and my guess is that it's somewhere between 10,000 and 24,000. The turbocharger is there both to get me to that optimum altitude quickly, and to give me enough power to make the most of it.
 
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The short HR wing is the not the best design for high altitude but the turbo allows full power to be maintained to say 24,000 feet plus depending on MAP used. This results in higher speeds than an atmo Rocket can attain. Higher speeds mean lower alpha. Due to ATC and oxygen system concerns, it's unlikely you'll be flying much above this altitude and even more likely you'll be below 17,500 most of the time. It would perform just fine here here with 260-300 hp available.
 
DesertFlier said:
Pierre, increased angles of attack are what I'm looking for actually, to a point. I don't have any personal experience with the HR2, but this is how I understand wing operation for airplanes in general:

The wing is at its highest angle of attack at slow speeds during takeoff and landing, when the aircraft is closest to stalling. This isn't the most efficient, but it's creating enough lift to hold the aircraft up, and enough drag to help slow it down.

At the opposite end, when the aircraft is in cruise, the angle of attack is at its lowest. Induced drag is still the same (you're still lifting the same weight), but the wing is at less than its optimum angle of attack (not an optimum lift-to-drag ratio), and form drag predominates.

But, if you climb up higher, you do have to increase alpha to hold up the same weight, because the air is less dense. At some point, you will reach the wing's optimum alpha and thus its maximum lift-to-drag ratio. At this point it will take a minimum amount of thrust to overcome the sum of all the drag forces on the aircraft.

Which brings me back to my original question: At what altitude does the stock HR2 wing reach its optimum angle of attack at gross weight? I realize the HR2 has stubby constant-chord wings, but there's still going to be a point where they are at their best, and my guess is that it's somewhere between 10,000 and 24,000. The turbocharger is there both to get me to that optimum altitude quickly, and to give me enough power to make the most of it.
Click to expand...

Gosh, have you thought about maybe the possibility that maybe John Harmon, the creater of the Harmon Rocket, might be able to give you that information? Who knows, if you ask him nicely, he might even build one for you with the wing specs you require....
http://www.harmonrocket.com/
 
An EVO wing is the only choice for a turbo Rocket. It has a higher aspect ratio to take advantage of the alititude, and the CG envelope to accept a turbo....

The best solution for a Turbo would be a top induction -550 powered airplane, that would leave room under the engine for the turbo set up.

Lets use Ole '84 as the baseline.. It currently has a 23/23 critical altitude of 8500 ft... at that altitude it indicates 180 KIAS will true right around 206 KTAS on a summer day burning 13.5 gph on the rich side....

So, lets suppose we put a medium sized turbo on my airplane and boost the critical altitude up to 18,000 ft. The rule of Thumb says that TAS increases by 2%of IAS/1000 ft of altitude when power remains constant, so that means the Turbo Rocket should true about 19% of 180 or 34 kts + 206, or exactly 240 KTAS which is the airframe redline.....

This would be an impressive airplane, but it would require a very disciplined pilot, to keep it in the envelope.......

This would be an airplane that would easily blast through the redline in any descent and sooner or later, there would be problems.....


Tailwinds,
Doug Rozendaal
 
B25Flyer said:
An EVO wing is the only choice for a turbo Rocket. It has a higher aspect ratio to take advantage of the alititude, and the CG envelope to accept a turbo....

The best solution for a Turbo would be a top induction -550 powered airplane, that would leave room under the engine for the turbo set up.

Lets use Ole '84 as the baseline.. It currently has a 23/23 critical altitude of 8500 ft... at that altitude it indicates 180 KIAS will true right around 206 KTAS on a summer day burning 13.5 gph on the rich side....

So, lets suppose we put a medium sized turbo on my airplane and boost the critical altitude up to 18,000 ft. The rule of Thumb says that TAS increases by 2%of IAS/1000 ft of altitude when power remains constant, so that means the Turbo Rocket should true about 19% of 180 or 34 kts + 206, or exactly 240 KTAS which is the airframe redline.....

This would be an impressive airplane, but it would require a very disciplined pilot, to keep it in the envelope.......

This would be an airplane that would easily blast through the redline in any descent and sooner or later, there would be problems.....


Tailwinds,
Doug Rozendaal
Click to expand...

And you would seriously have to watch the CHT's as they would easily go above redline temps as well.

Is your critical alt. only 8500 ft.? Did I miss something...?
 
B25Flyer said:
This would be an impressive airplane, but it would require a very disciplined pilot, to keep it in the envelope.......

This would be an airplane that would easily blast through the redline in any descent and sooner or later, there would be problems.....
Click to expand...

I don't have a problem flying on the edge of the envelope. Part of it is pilot discipline, but part of it is making sure the aircraft adequately warns the pilot of dangerous situations. I have plans to build a glass panel, and as I understand it at least some EFIS computers can calculate true airspeed and display a barber pole on the airspeed scale, as well as an audible overspeed warning. If possible I'd like to integrate an autothrottle with the EFIS so the computer can adjust the throttle during descent to keep pilot inattention from resulting in an overspeed.

As for the wing design, as I understand it a higher aspect ratio is going to improve wing efficiency regardless of airspeed and altitude. So in that manner the Evo wing would be a step in the right direction. If I wanted to spend more years and dollars, I'd like to throw away the whole Vans/Harmon wing design and start over with something that's better suited to higher speeds. But alas, I don't think that will be happening...
 
DesertFlier said:
I'm still very much in the dreaming stages of an aircraft project. The aircraft I really want is a Harmon Rocket II.

Here's my thinking:

I want cruise speeds as high as possible with fuel flows as low as possible (who doesn't?). We know the HR2 is redlined at 275 mph TAS. We can't go faster than that, but can we be more efficient?

You can pick up bits of efficiency here and there. You can use GAMI injectors and an engine analyzer to run lean of peak, lowering fuel flows. You can use electronic ignition to squeeze more power out of the engine by optimizing the timing. By carefully designing the cowling and cooling system, you can minimize drag there.

What I'd really like to build is a turbocharged Rocket. You can't fly faster than 275, but you can fly higher in the thinner air and, in theory at least, burn less fuel doing it.

So, are there any turbocharged HR2s out there, or is anyone working on a similar aircraft? Keep in mind I'm already aware of the disadvantages of cost and increased maintenance. I'm just curious to see what others with more experience might think of this idea.
Click to expand...

Hi Desert Flyer,

What are you currently flying?
 
12,000' was a good number to cruise at x-ctry in the HR3 and I never went above 14 as it didn't do anything for me.
The wing is the factor and all the F1 EVO guys know that.
I didn't need more speed (I can't believe I just said thet) from the HR3, I already had that, but to go higher would require a tapered laminar flow airfoil or I was just burning gas and stressing the powerplant with high EGT's, CHT's and oil temps.
The HR2's and F1's were good down low and the F1 EVO's were good up high.
I'm sure all the armchair quarterbacks who don't own an airplane or know any different will jump in and argue. :rolleyes:
My 2cents.
 
Supercharged Rocket

I've flown the supercharged F1/EVO airplane that Wolfgang built a few times. It has an IO540 with a Vortech supercharger, and produces about 360hp. Not sure how much boost the Vortech can produce, but I've seen near 40 inches on takeoff, which launches the airplane with authority.

The airplane is fast, and does pick up speed when pointed down hill pretty quickly. That's come into play recently, as I've done a bit of aerobatic instruction in it from the back seat but its totally manageable if the pilot maintains awareness and thinks ahead.

I admire your want for an airplane that can both go fast and be efficient, but the only good way to do that is to manage drag at the higher altitudes needed for efficiency. The wing is the biggest single contributing component to drag on the airplane, so its of utmost importance to mate a well designed wing to the airplane if fast + efficient is the goal.

Induced drag isn't exclusively tied to aircraft weight; its really better to relate it to angle of attack (more AOA = more Cd_i). So the operational factors that drive AOA higher also drive Cd_i higher: slower speeds/higher weights/increased load factor are typically responsible for driving Cd_i up. As altitude increases, the wing will produce more induced drag for a given TAS due to drop off in dynamic pressure with altitude.

In terms of wing design, aspect ratio has a major effect on induced drag, with higher AR driving induced drag lower. So, for good altitude operation, that translates into the need for a higher aspect ratio wing, and the EVO wing wins that contest hands down, versus the short wing Rockets.
 
My friend and traveling buddy, Wayne Hadath, flies a fast straight wing rocket, I have an EVO wing. Although we do a lot of cross country work we rarely get extended high altitude travel, usually due to weather considerations. Year in and year out at altitudes of 8000 feet or less we burn the same amount of fuel. We always fly at 22 squared burning between 10 and eleven gph.
Two years ago on the way home from Pagosa Springs Colorado we had 3 hour leg at altitudes in the 10.5 to 13.5K range. I set up my normal power setting with Wayne off my wing. At the end of the three hour flight I had burned exactly 30 gallons and he had used an extra TEN gallons just to keep up.
With four years of effort in drag reduction I now have an airplane that is flirting with red line in straight and level flight without the expense of a turbo charger. I flew the AirVenture Cup Race this year at 17,500 feet with an average speed of 228 knots. I had to start my descent 125 miles out to keep from busting red line. I am not sure that there would be any value in adding a turbo to this aircraft. Spend your time and money on the proper wing and drag reduction.
 
Wolfgang's turbo'ed Rocket was fantastic. He did a superb job on building it as well. He is a real craftsman. I wanted to do something similiar as his, but came to the conclusion that (for me, anyway) the cost, plus the many, many hours of time that would be needed to get it to fit, and tweaking it for proper operation would have taken away the pleasure of flying it, and the actual numbers in cruise didn't increase that significantly. As others have posted, you would be limited by the Vne which would be realized much sooner before you even got close to the output of the TC/SC. The CHT's will also require you to ramp up the fuel flow and thus eat into your economy somewhat. On paper, the economy (MPG) turns out very, very close with the SC vs normally aspirated. For the people with Rockets that "merely" pump out 260 HP, I have yet to talk to any of them that were not thrilled with the performance they got out of them- climb, or cruise(Having said that, my engine puts out 290+ HP). With 260, Vne is still something that they have to pay attention to as they frequently flirt with that number. I think the real performance you would be looking at with the TC/SC would be the climb- now, that is someting that we ALL can agree on would be awesome!

OK, as you all now realize, the real reason I have to "poo-poo" the TC/SC set-up is because it is beyond my price/skill-set abilities, and my rant merely makes me feel better for not having done it. ;)

Look around and find a "stock" Rocket to get a ride in- I think you would agree that there is really nothing lacking-
My .02.
 
Tom Martin said:
Two years ago on the way home from Pagosa Springs Colorado we had 3 hour leg at altitudes in the 10.5 to 13.5K range. I set up my normal power setting with Wayne off my wing. At the end of the three hour flight I had burned exactly 30 gallons and he had used an extra TEN gallons just to keep up.
Click to expand...

The thing that one has to keep in mind about the EVO is that the additional wing area produces both more induced and parasitic drag. The three other penalties are reduced cg range, ailerons that are heavier, and an additional 75lbs to the empty weight. With all of Tom's speed mods and with Wayne having a stock airframe, burning the same speeds/fuel burns, negates some of the strong points of the EVO wing for I would venture to say at least 99% of the flying I myself typically do. This is why I never felt favorably about the EVO after flying it for a dozen hours. Wasn't a game-changer for me. The short stubby wing still works well for me.

The other question I have is what if one just added to the wingspan of the sport wing and beefed it up accordingly to have the same area as the EVO, if one would get similar performance up high. The RV-10 exhibits some similar characteristics in this regard so I'm not convinced that tapering a wing offers up as many advantages as one might think.
 
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rocketbob said:
The thing that one has to keep in mind about the EVO is that the additional wing area produces both more induced and parasitic drag.

--snip--
Click to expand...

IIRC, the EVO wing has slightly less surface area than the square wing, by a couple of ft^2. You are correct about the extra weight - I was told that this wing was originally designed for a heavier airplane, so it is stronger than needed for a Rocket airframe.


There are definitely tradeoffs with the EVO wing, but I really like the high altitude performance as well as the slow speed landing characteristics. My EVO Rocket lands slower - by seemingly a significant margin - than my RV-7A.

Mark Olson N407V RV-7A N16XV F1-EVO
 
I am perhaps sounding too critical of the standard wing on a rocket. For pure fun, cost and weight it is hard to beat. This thread though, is about putting a turbo on a rocket, and due to the altitude limitations of the square wing, in that particular environment I can not say that it would be worth the time, expense and effort.
 
I really appreciate everyone's input, particularly from those that either have flown or are flying various Rocket designs.

From this discussion, I can see that turbocharging a standard rocket may be trying to get blood from a turnip. I have no doubt that the standard HR2 is a fine airplane, but it's not going to do what I had planned it to do.

On the other hand, there's simply no room in my budget for a 26,000 dollar wing kit. Even building a stock HR2 is going to be a financial stretch. There's also no way I'm going to be stepping up in to any higher/faster classes of aircraft. One of the great things about Van's series of aircraft is that they're inexpensive, relatively speaking. When you start having to redesign major parts of the airframe, the inexpensive part goes out the window. The reason I had suggested a turbo is that it's a relatively cheap way of adding performance. But efficiency is important to me, and if pushing forward on the throttle is simply going to make some oil companies richer without getting me there significantly faster, then it's not for me.

Which leaves me with three options:
I can wait a long time to save money and buy the EVO wing.
I can redesign the wing myself and get the airplane I really want (many years and many dollars invested).
Or, I can stick within my budget and skill set and simply accept that the standard, non-turbo HR2 is a heck of a fast airplane, though not any faster than the ones just like it.

I have some thinking to do...
 
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Paul,

Here's some more emperical evidence on Sport vs EVO wing, and a couple thoughts. I have a super six with nearly identical wings to Wayne's F1. My wings were built in 1998 to HRII specs (as I understand it).

Mark (F1Boss), Wayne and I spent much of last season trading races (all of us were chasing Tom). Our top speeds were often fairly close last year, though Wayne is faster when his engine is running in top shape, and Mark will gain speed now that Pesky's engine is broken in. I gots work to do!

Last summer, we had a good side by side comparison at Airventure Cup, where we were close (and talking on a tactical freq) throughout the race. In fact, after taking off 30 seconds apart (Wayne, then Mark, then me) we were all abeam each other as we made an initial level off at 15,500', where we had climbed for tailwinds.

Tom had gone up to 17.5 with his EVO and was enjoying better tailwinds, so Wayne climbed up there to try it, and did not like the way his airplane felt there that day. He descended to 9.5 to chase horsepower, and lost the tailwind.

Meanwhile, Mark and I stayed at 15.5, and with his EVO wing, he slowly crept away from me, till he was a couple miles ahead. I lost sight of him in the descent, but caught him a bit in the dash to the finish, and we finished 4 seconds apart (he being faster :().

The EVO wing showed its strength at that altitude, plain and simple, as before that we'd been very well matched down low. The Sport wing does well at low altitude, and Wayne and I have short flat tips we use for racing down low too, which EVOs can't do...but apparently don't need to :mad:. For cruise, the testing I have done doesn't show a precipitous drop-off point where the Sport wing starts to perform poorly. But as the engine loses HP as you climb, and you don't have the ponies to push the wing at faster TAS (like you can lower), that wing shape just starts to produce a lot of induced drag as max cruise speed drops and thus cruise AOA increases slightly. Its on the order of about 3/4 knot per thousand feet. On a good day I can get about 217 kts at SL, and on a few X-C tests, I was able to get 204-205 KTAS at 17.5. Its a fairly linear loss in the climb too, though the speed loss curve appears flatter below 10K or so and a little steeper above. That's at WOT/2700. Not sure how the EVO wing compares, but I'll bet the losses in the climb are flatter above 10K than for the Sport wing. Tom may have some numbers on that.

For normal X-C cruising, I often fly WOT/2300, and get 198-200 KTAS at 12.5/13.5K, a little better at 10.5. (And FWIW, often on O2, since the DA is higher in the spring-summer-fall) racing season. FF is around 14 gph (ROP, and that's +/- depending on altitude).

A Rocket (HR or F1) with a Sport Wing is really a capable X-C platform. I know more F1 than HRII drivers, but maybe Smokey will chime in, as he has a nice HRII that posts good numbers.

The EVO wing rides a little different than the Sport wing too, and Tom has a good story about that as well.

Tom is the only guy approaching Rocket Vne in level flight, so if you want to build a fast HRII, go to school on his building techniques, and incorporate what you can and want into your build (or devise new clever ways...that we can copy! :)). If you build it fast, it will water your eyes in performance, and will be a great traveling machine. If you want to turbocharge or turbonormalize to maintain the horses up higher, you'd probably be able to drive the Sport wing faster than we can up high, but you'll reach a point of diminishing returns sooner than you will with an EVO wing, and your FF will show it (I think...no expert there!)

Either way, you'll love the airplane! Have fun whichever direction you go, and it'll be fun to watch you develop the final product!

Cheers,
Bob
 
You'll probably find the performance of a standard Rocket pretty impressive unless you've been flying turbine stuff. But...

If your dream is to go turbo I say do it. The turbo will maintain power at altitude so the higher you go, the faster you go until you reach critical altitude. The semantics about this or that wing don't matter much when you have 50% more power available over an atmo Rocket at 18,000 feet and you'll leave them far behind in the climb too. Maybe not the most efficient way to go but it will be fun.:)

Maybe you could look at an HR III (still straight wing) which has a Vne of over 350 mph if I recall. A good turbo system might allow you to do that in level flight at altitude.

Comparisons of how an atmo version wing performs up high and a turbo are not really valid since the turbo goes faster and keeps the alpha lower. Power gives you climb, speed and ceiling.
 
Tom Martin said:
Year in and year out at altitudes of 8000 feet or less we burn the same amount of fuel. We always fly at 22 squared burning between 10 and eleven gph.
Click to expand...

I apologize for the thread drift, but a question for Tom...can you share what KTAS you typically achieve in cruise at the above mentioned configuration? The reason I ask is that you've obviously done a teriffic job at drag reduction on your airplane base on the consistently high speeds you post in the SARL events. But I'm curious as to the level of efficiency improvement you get in more typical cruise configurations compared to "stock" EVO (or sport) wing rockets. Let's say that you're cruising in the 10k altitude range and configure for 200 KTAS...what would be a typical FF for your airplane? Thanks!
 
I flight plan 190 knots, wheels up to wheels down, 22 squared, burning between 10 and 11 gph. As mentioned earlier under 8000 feet Wayne and I get similar fuel burns. Keep in mind that he has a clean fast rocket. I have rarely done any cross country flying with other rockets and so I am not able to definitively answer your question. Drag reduction is always a good thing and as you know the faster you go the more it comes into play.
I do not have extensive data for other power settings as I either fly a nice comfortable 190 knots or I am balls to the wall during races.
Feel free to contact me directly for any specific questions that are not related to this thread.
 
I'll have to do some speed tests with mine sometime.
What i can say for sure is that i keep mine normally at 22 squared and i see about 215mph religously at low altitude.
Maybe you'd like a nemesis or thunder mustang.;)
 
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DesertFlier said:
I'm still very much in the dreaming stages of an aircraft project. The aircraft I really want is a Harmon Rocket II.

Here's my thinking:

I want cruise speeds as high as possible with fuel flows as low as possible (who doesn't?). We know the HR2 is redlined at 275 mph TAS. We can't go faster than that, but can we be more efficient?

You can pick up bits of efficiency here and there. You can use GAMI injectors and an engine analyzer to run lean of peak, lowering fuel flows. You can use electronic ignition to squeeze more power out of the engine by optimizing the timing. By carefully designing the cowling and cooling system, you can minimize drag there.

What I'd really like to build is a turbocharged Rocket. You can't fly faster than 275, but you can fly higher in the thinner air and, in theory at least, burn less fuel doing it.

So, are there any turbocharged HR2s out there, or is anyone working on a similar aircraft? Keep in mind I'm already aware of the disadvantages of cost and increased maintenance. I'm just curious to see what others with more experience might think of this idea.
Click to expand...

Time again to beat that horse!
 
DesertFlier said:
I'm still very much in the dreaming stages of an aircraft project. The aircraft I really want is a Harmon Rocket II.

Here's my thinking:

I want cruise speeds as high as possible with fuel flows as low as possible (who doesn't?). We know the HR2 is redlined at 275 mph TAS. We can't go faster than that, but can we be more efficient?

You can pick up bits of efficiency here and there. You can use GAMI injectors and an engine analyzer to run lean of peak, lowering fuel flows. You can use electronic ignition to squeeze more power out of the engine by optimizing the timing. By carefully designing the cowling and cooling system, you can minimize drag there.

What I'd really like to build is a turbocharged Rocket. You can't fly faster than 275, but you can fly higher in the thinner air and, in theory at least, burn less fuel doing it.

So, are there any turbocharged HR2s out there, or is anyone working on a similar aircraft? Keep in mind I'm already aware of the disadvantages of cost and increased maintenance. I'm just curious to see what others with more experience might think of this idea.
Click to expand...

How's the progess of your turbo Rocket coming? Have you flown off the 50 hours yet? :cool:
 
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