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F1 EVO wing is it worth the extra cash?

bostontea

I'm New Here
I want to build a quick build and am trying to decide between a RV-8, F1 rocket with the sport wing or the F1 evo rocket. I owned a RV-4 and still regret selling it With a 160 hp O-320 and a fixed metal prop. It was almost perfect just needed more power, a constant speed prop and lots of expensive avionics for IFR flight. I want a fast aircraft for long solo cross country travel and occasional IFR.

F1 Evo kit (w/emp) ..Lycoming Config????????????$49720
F1 Evo kit (w/emp)..TCM.IO-550.Config??????????.$50700
F1 Sports QB kit (w emp kit)????????????$44270
RV-8 QuickBuild kit ??????????????????$28105
 
You're talking about three different planes here. The differences are many between them. You need to get yourself a ride in each and then make the decision. What is your mission profile? Pick the one that will do it for you. They are all capable of IFR. The EVO is the most stable of the three for IFR work.
 
What's your mission

If money is no object then build the EVO F1. It is a bit more complex than the Sport wing but it will also give you a better ride and is easier to handle in IFR. The sport wing is very neutral in all axis and is not the best IFR platform if that is what you are flying all the time. If yank and bank is your thing then build the Sport wing F1. If your wallet is making the decision then build the RV-8. The sport wing F4 (180hp) Rocket may come out next year if you can wait.
 
F1 Sport Wing

I've flown an earlier Harmon "rocket" with its itty-bitty chopped off wings. It was sled-like, not very fast for the installed HP and bled energy like a pig in turns. I was glad to climb back into my 200HP RV4.

IMHO the F1's are too pricey. What extra performance you get there is offset by much higher cost to operate (the 550 up front), poor tradeoffs in terms of aerodynamic and propulsive efficiency (exception: the EVO wing), and higher kit costs.

The Harmon and/or F1 aircraft are essentially worked-over RV's. The concept behind these airplanes is simply: chop the wing and add more cubes under the hood.

This doesn't work well for two big reasons: 1) The RV's already have a fairly low aspect ratio wing with an antiquated airfoil. Chopping it only kills aerodynamic effeciency, and makes it lose energy while loaded up even worse than the stock wing. 2) HP is the MOST difficult way to go fast. Speed in a piston driven airplane varies with the CUBE of the horsepower. That means to double the speed would take 2^3 power, or 8 times the power. The ultimate extrapolation of this madness is the HR-III with 400 HP. This flying fuel tank has only 1 seat, doesn't do much better speed-wise than the HR-II and I'd bet it flies like a brick. More HP means more fuel burn, less payload, shorter range, etc. Instead, spend your propulsive dollars on the best prop available and a quality 4-banger.

The "rocket" I flew would cruise around 230 mph with 260 HP installed. My friends RV4 would cruise about 210 with two fewer cylinders. Power off the Rocket came down faster than it would go up - it roared downhill like a manhole cover on edge. Not my idea of a good time if that happened IFR on top. :eek: I just don't have that much trust in these old engines.

If I had to make your choice today, I'd build an RV-7 or 7A and plumb the outer wing panels with extra fuel to get outrageous range. Pack that nice wide panel with all the goodies you can stand. Feed two fewer cylinders with 100LL. Have the advantage of industry leading support and a HUGE builders network.

Fly safe...
 
Wrong Airfoil

Of course I love the Rocket. Mark Fredricks at team Rocket is a nice guy, smart and a stright shooter. Harmon is a natural engineer, but I have some reservations/opinion about how they should have done the EVO wing.

First the data on the Team F1 Rocket is there. He had it test flown and asked for unbiased opinion. It's all there and I think its pretty straight. The data is there and accurate, I think about 10 mph advantage. The top speed is a little higher and the low end is maintained or almost maintained with the slotted flaps. Slotted flaps are heavier and more complicated, still nicely done from what I see.

Now for the negative, they used the WRONG airfoil in my opinion. They used a laminar airfoil.

From Team Rocket: "The new airfoil is an MS(1)-313. This airfoil series, along with the LS(1)-xxx series, and the NLF series, were developed by NASA in the seventies. Testing shows a potential 20% decrease in wing drag through use of these air foils. A secondary positive side of these air foils is that surface degradation through rain, or insect leading edge contamination, does not cause a significant problems: a contaminated airfoil still provides drag equal to our current air foil, the NACA 23013.5."

One draw back with this series of laminar airfoils is they don't do as well in the real world as they do on paper. Their efficiency is over a narrow range of lift coefficients. Also, deviation from theoretical airfoil shape can null & void even the performance in the airfoils sweet spot. Burt Rutan tried using laminar airfoils, like on canards. It scared himself in rain with loss of lift. The modified and improved laminar airfoils still lose lift in rain but not like the early ones. That is not an issue with main wing on a Rocket, but how clean does it have to be? Are rivets too much like "rain"? Laminar flow is hard to get and keep in the real world.

NASA developed these new airfoil shapes (GAW, LS, MS, NLF) supposedly for general aviation, which have pitching moments almost ten times that of some of the older sections (like NACA airfoils). NASA’s definition of general aviation is a King Air, not a Glasair. These sections were optimized for the higher wing loads.

The Piper Tomahawk uses a GAW airfoil and has some weird stall and spin characteristics for many reasons, but the 'GA' airfoil is part to blame in my opinion. Time and again the Laminar airfoils have been a disappointment. One of Piper's last all new GA designs was the high performance pressurized Malibu/Mirage. It uses 230XX airfoil. It was designed by the same guy who designed the Quest Air (flying egg), which also uses the 230XX airfoil. It's not that he did not know about the NASA airfoils, just that they were not a good fit. The Quest Air has a similar looking tapered wing and performance as a Rocket. However the Questair is faster. The Questair wing looks like the EVO wing in overall area and span. My point is they stayed aways from the new laminar airfoils and stayed with the 1940's technology. I'm not a fan of so called laminar flow airfoils across the board. They always seem to disappoint. It's more of a bad match for the airframe than a bad airfoil. There is one airfoil that always pleases, the 230XX airfoil! Sound familiar? Yep its the same one Van uses.

The 230XX airfoil can just as easily be in a tapered wing (both plan-form and thickness for root to tip). The 230XX airfoil is used on some many famous and highly regarded planes to list all the way up to some Cessna Citations. Part of the reason those famous planes are so well loved and regarded I think was the wing's airfoil, 230XX.

The EVO airfoil is not the one I'd used. They would have got better feel and the same speed or better, both at the high and low end with the 230XX, in my opinion. We all know how great the 230XX airfoil is. Why not keep it? It's easy to get enamored with the promises of laminar flow airfoils. Unfortunately their low drag characteristics extend only over a narrow range of lift coefficients. In the real world the benefits are not as great as hoped. Is the EVO wing bad? No, definitely not bad, just it would be better with the 230XX airfoil. Is it worth the money? That's up to you and your accountant. It does look cool. You really NEED to fly both to make the decision!
 
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EVO Airfoil and the NACA 23XXX

Guess who emplored Mark Frederick to do a tapered wing on the F1? I did way back in the early 90's. Unfortunately, I believe the previous post is correct - the EVO uses a NLF airfoil (natural laminar flow). These were developed originally for use on sailplanes. Also, the EVO wing gets the taper ratio wrong. Not enough taper to get optimum spanwise lift distribution. Oh well.

The NACA 23XXX (called a "five digit airfoil) was done in 1931. This antique was NACA's attempt to do a zero pitching moment coefficient airfoil. Back then, they were trying to get rid of the tail trim loads.

Unfortunately (again), the NACA five digit airfoils achieve this zero moment goal by using alot of camber in the first 20% of chord. The rest of the airfoil is symmetrical. This front-loaded, zero-moment design has its problems though and they're not insignificant.

The forward camber runs the min pressure point on the airfoil way forward and then you have a very nonlinear pressure recovery after that. This produces a very sharp stall break, and has lousy drag numbers by todays standards.

But - it was the airfoil on the S**** Playboy that Van reverse-engineered in metal. So we've inherited it here. My old RV4, for one, had just about zero prestall buffet.

Never the less, the old Five-Digit airfoils abound and their sharp stall is engineered out on certified aircraft with planform bandaids, leading edge devices, twist, etc. It has served us well over the decades but I for one wouldn't revive it in the face of 60 year improved technology.

You all will have to wait a bit longer to see what I have in store for the RV world...
 
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Those are a couple of very good dissertations regarding the negative aspects of the EVO wing. Personally I do not have the engineering background, nor the time to search the internet, to describe how the EVO theoretically flies. My comments will have to be based on what I have found after 700 hours of flight in standard rocket wings and 220 hours of flight with an EVO wing.
First the negatives
It is more expensive
It is heavier, but also much stronger, and I do think that weight could have been saved here as it was designed for speeds that we will not get to with the engines we use.
The roll rate is less than the sport wing. It is very similar in roll rate to my RV4 but it is just a tad heavier on the stick. It might take three fingers on the stick rather than two.
Both wings can carry a huge load due to the weight of the large engine out front. With the EVO wing the stick feels a bit lighter with aft load than does the sport wing. Having said that, the EVO stick feels better solo than does the sport wing, it is not big deal either way.
Now the positives
The EVO is slightly faster on the top end, how much depends on the airplane.
The EVO is a lot slower on the bottom end. The stall is at least five knots and probably closer to ten knots slower. It actually has ground effect and my landings on our home strip are significantly shorter than with the sport wing in the order of 300 to 500 feet.
Even though the roll rate is slower than the sport wing it will out turn the sport wing in a dog fight. I know that does not seem to make sense but it does, perhaps one of the theoretical guys can describe how that would be possible.
The EVO wing does not look like 6000 other RV wings. I realize this is my personal opinion and has absolutely nothing to do with flight characteristics but we do like to spend money on things that are unique so I consider it positive.
It is extremely stable in flight, a joy to fly on cross country trips. My wife suffers from motion sickness and I have been unable in the previous twenty five years to share my love of flight with her. This last two years she has traveled with me on numerous trips. That makes the extra price worth every penny to me.
There seems to be no negative effects on the wing due to the normal contamination of leading edges, either bugs or rain. The designer of the wing described the airfoil to me as being a 75% laminar flow shape, what ever that means. To me it means that, in use, I have not had to change the way I fly compared to the sport wing.
And I had an absolute blast flying in the last two SARL races with this airplane. I should find a better pilot to fly the plane so that we could see how well it would really do!!
This is how I sum up the differences in the two wings; The sport wing is fun airplane that also good for cross country flights while the EVO is a great cross country airplane that is also fun to fly.
 
Hi Tom,
Thanks for providing us with your real world experience.....and to Bill/George for their viewpoints.

Another viewpoint....I fly a lot of formation and didn't want to look like a 'disimilar aircraft' when flying formation with other RV's....therefore I chose the Sport Wing model. Glad Mark makes (and supports) both models.

Also, to respond to Mr. Wightman's comment:

"Power off the Rocket came down faster than it would go up - it roared downhill like a manhole cover on edge. Not my idea of a good time if that happened IFR on top. I just don't have that much trust in these old engines."

My experience couldn't be farther from his.....When the engine quit on the HRII it actually flew quite nicely....even with the 80" Hartzell windmilling up front. True, I wasn't going to ride any thermals but there was nothing scary about flying the airplane at all. Best to get as many viewpoints as possible.

Also...I saw the numbers that were posted from the race this past weekend...congrats to all the Rockets for some impressive speeds. Looks like Tom edged out Wayne....this time :).

To answer the original post...Is is worth the extra cash?? Probably best to fly both and then decide for yourself. I personally haven't flown in an EVO but trust Tom's experience and unbiased opinion. My wife won't fly with me either....but I don't think the EVO wing will help in my case :rolleyes:
 
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"Theoretical Guy" answers:

Even though the roll rate is slower than the sport wing it will out turn the sport wing in a dog fight. I know that does not seem to make sense but it does, perhaps one of the theoretical guys can describe how that would be possible.

Tom - Excellent post! Your write-up is the best I've ever read detailing the real world differences between the standard and EVO F1 wings.

To answer your question: The EVO out turns, flys slower better, and is more stable mainly due to one big concept. Its because the EVO wing is longer in span for its area - something we call "aspect ratio".

The wing on an airplane like the RV's or the F1 is the single largest drag producer we have. Aerodynamic drag made by the wing comes in essentially two types: 1) Drag due to lift 2) Drag due to area and shape, which breaks down into several subcategories.

Now to the point: The aspect ratio is HEAVILY tied to number-1 above. Lower aspect ratios make lots more drag due to lift than higher aspect ratios do. The sport wing has the lowest aspect ratio of the bunch, and thus makes much more drag due to lift. When you're turning and burning with the bandit on your tail, that stubby wing is making gobs of induced drag.

Also, with its reduced area, the sport wing must operate at a higher CL overall. This is probably OK in 1-g flight, but at elevated load factors I'd bet it places the old 23013 airfoil waaaay up on the drag curve. So we take a hit in number-2 above more than we should.

As for landing, and stability: The EVO with its tapered planform achieves a much more efficient span-wise lift distribution. The sport wing, not. The EVO wing makes more efficient lift, square foot for square foot than the stub wing does. Its longer span makes it more stable in roll due to higher roll inertia (mass distribution and you said it was heavier) and it has better aerodynamic roll damping. The sport wing could be thought of like a car with a short wheel base.

Glad to hear how the EVO wing has worked out to be the right choice for you. Again, great write up!

RV6Rick - my comment on how fast the HRII ran downhill was based on back seat observation of its rate of descent in the pattern power off. Comparing it to the docile RV4, it was much faster when heading downhill. This is a highly subjective call, though. I'd bet the F1 does better than the HRII.

Pierre: Patience patience. This is a BIG and EXPENSIVE job.
 
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Hey Fellas:

Be careful what you read on the internet -- from my experience I'd suggest confirming almost anything you hear!

Evo wing: This wing was designed to fit the M-1, to be built by HPAI. SO, it was designed for a heavier gross weight ship from the start, which gives it a huge margin on the Evo -- a good thing in most cases, except in the weight category: it is approx 50 LBS heavier in comparison to the Sport wing. Oddly enough, performance didn't seem to suffer, tho I'm sure a lighter wing would have given even better numbers. The top speed increase was exactly what the engineer had predicted (5%), but the slower stall was the part that surprised me, tho I should have seen this coming (tapered wings are more efficient at higher alpha angles -DUH!)

Our investigating of using the 230XX instead of the newer foil showed a similiar increase, if we fudged the figures enough. I was worried about the stall, knowing how the RV doesn't really talk to you before it lets go, so we went with the newer foil which gives plenty of warning.

The additional problem with the wing, derived from its intention to be used with a heavier gross weight ship, is its area: simply too large. We ended up with a bit over 100SF, where about 85SF would have been optimal for cruise at altitudes below 12000MSL. I liked the slow approach and stall speeds, and a re0design would have raised the price of the wing about 50%, so we stayed with what we were handed.

As for the Questair Venture wing, it did start with a 230XX foil, but it was changed from that rather quickly (stall characteristics again!). Do your investigating before you report! The narrow chord/CG range of this wing is OK with a SBS design, but would not work on a tandem arrangement for those same reasons. The Venture wing uses similiar PERCANTAGES of chord for CG range as are used on the RV series, but the mean chord is very narrow, so the resulting CG range is also very narrow; it just won't work on a tandem arrangement where the pilot sits in the front seat. Trivia: Do you now the WW2 era B-24 has a 9" CG range, again due to its narrow chord wing??!!

Evo airfoil:
The CZ engineer started with the MS(1)-313, but we ran into the same thing everyone else using the new foils did: high pitching moment. We flattened out the aft camber to the limits of the aileron and flap design, and this gave us a foil with an approx 60KT wide trim band. This trim band talks to the pilot in terms of trim tab adjustments: the pilot more or less trims for load once in climb, and never touches the trim again until the ship is slowed for approach. I have not heard from any pilots who do not like this particular personality trait.

BTW: Glasair uses the LS(1) or GAW foil; Lancair/Columbia and Cirrus use the NLF foils, again all are modified in the TE area to reduce pitching, and also at the LE (Lancair and Cirrus) to tame the stall to certified limits.

The MS(1)-313 is supposedly about 40% laminar, where the 230XX is about 20%; more attached flow is probably better in just about any case. We haven't seen degradation effects that compromises performance to a large degree -- NASA says it (and other later-designed foils) perform more like the 230XX, or other non-laminar foils, with bugs on the LE.

Current sit rep: We had to stop dealing with the CZ boys in the spring due to the dollar/euro slide. The currency situation at present allows us to produce parts and QB kits here in the USA again, but the biggest positive aspect of this is that I get to make changes to the Evo wing to further optimize it for cruise flight, and attend to the slightly slower roll rate.

Stay tuned -- I think you all will appreciate the Evo II, both in terms of performance and price. I'm not quite ready to make a formal announcement of the new developments, but we are close....

Carry on!
Mark
 
Some of the most successful aircraft designs utilize the NACA 230XX airfoil, RV's, Bonanza's, Swift's, F8F Bearcat, Corsair, etc. just to name a few.
 
Airfoil choice

OK y'all, I know the Five Digit (NACA 23XXX) airfoils are used in abundance. But I also know - and yes I have done the research - those airfoils were done by NACA (not NASA) in 1931 in an early effort to get rid of pitching moment. In fact, all the NACA airfoils were "lab rats", never specifically designed to be fitted to any airplane. The designers of the day simply used what NACA doled out. The research was mandated and funded by the US congress following WWI when the US was falling behind in aviation technology.

We now know that negative pitching moment is not a problem to control and does not lead to large drag numbers by way of trim loads on the h-tail. There's more than one way a designer can move static margin, CG, and Cm/Alpha curves around to fit his needs. Pitching moment is only one ingredient in the soup of variables that must be addressed.

Bottom line: 70+ years have lapsed since the 23XXX was done. I know, I know there's a whole slew of airplanes that use it. But we've had better since WWII and MUCH better choices these days. In fact, just about all modern aircraft don't need to run a "stock" airfoil the government hands out. Now, a competent designer can cook up a mission-specific section on a desktop computer in just a few days.

I bet the EVO-II is worth waiting for! :D
 
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I gave a guy a ride in my Rocket early Saturday morning around the Taylor,TX race course and he said he had the last set of EVO's(and he wasn't giving them up) so this may all be moot. You can buy an EVO for $250K or

you'll have to wait for the EVO II!
 
The 230XX airfoil is faster than a LS airfoil?

But - it was the airfoil on the S**** Playboy that Van reverse-engineered in metal. So we've inherited it here. My old RV4, for one, had just about zero prestall buffet.

Never the less, the old Five-Digit airfoils abound and their sharp stall is engineered out on certified aircraft with planform bandaids, leading edge devices, twist, etc. It has served us well over the decades but I for one wouldn't revive it in the face of 60 year improved technology.

You all will have to wait a bit longer to see what I have in store for the RV world...
Well you sound like a real Aero guy, I have only stayed in a Holiday-Inn and sat next to a real Areo guy.

Stalls - I think personally the stalls on RV's are very mild; in fact they don't want to stall. I agree the buffet is nominal or minimally. Fair to say sharp but not dangerous. RV's need stall strips (to get them to stall) to do good snap rolls. If you want to get into MODERN than get an AOA device to warn you of impending 'danger'. For a plane that stalls in the low / mid 50 mph range, slower than a C-152, the danger is small.

The laminar airfoils are not known for mild stall properties. They may warn you but they break like a sob. The Piper Tomahawk uses a GA (laminar) airfoil. I flew one for 500 hours and taught in them. They had weird and unpredictable stall characteristics, like a snake bite, breaking right or left abruptly. I like the T-hawk a lot overall, had good times, but stalls are not a stong point. It flew fine but the T-tail added some more weird control issues both in flight and landing you had to adjust for.

MODERN - I don't totally buy the "modern" argument when presented with it. Auto engine guys say MODERN, yea but its heavier and slower. Again you know more about Aero than I, but in my experience with LF wings, they promise a lot but never really deliver. Two-dimensional data rarely is accurate for an actual wing, and other factors come into play, which I'll mention below.

LIFT? (l/d)
The Glasair III ( LS(1)-0413 airfoil) lost lots of sales when other planes out performed it, the Lancair and QuestAir to name two. The QuestAir beat a Glasair III silly with less HP. The QuestAir used the 230XX airfoil, 23015 root/23010 tip. Stoddard was confused. It's laminar airfoil was MODERN, it should have less drag, RIGHT? The reason was the LS airfoil had less drag but also made less lift. So the LIFT/DRAG for the QuestAir (230XX) was over twice the LS airfoil of the Glasair III in cruise condition, OVER TWICE! Stoddard made it worse by filling in the lower trailing edge cusp to get the stick forces down, decreasing lift performance further. It was a bad choice of an airfoil. No doubt there are better laminar airfoil choices Glasair could have made; still, modern is not everything. Ever fly a Glasair? They are fast but don't handle as lovely as a RV, especially in roll with the RV's 'frise' ailerons.

BOTTOM LINE
LF airfoils do have a narrow operating range, and they do have more pitching moment and less lift in many cases, apples for apples. Real airframe and real world performance will be different than the 2-D specs. The QuestAir with a 230XX airfoil is a faster plane than the Glasair III with a laminar airfoil? That is not a debate. The Lancair IV uses some custom and non laminar flow airfoil and is also faster I beleive. Yes the 230XX goes back to the 1930's or 40's but things have not changed much. It gets the job done. Bad stall characteristics are over blown in my opinion. Does any one fear their RV's stall? There is more than just low drag numbers to an airfoil, like lift and pitching moment.

Hey Fellas:

As for the Questair Venture wing, it did start with a 230XX foil, but it was changed from that rather quickly (stall characteristics again!). Do your investigating before you report!
Mark two or three refs show the QuestAir uses a 230XX? What did it change to? "The designer Jim Griswold... who also headed the team the QuestAir Venture, also designed the Malibu for Piper... both use the NACA 230XX." Ref http://nuventureaircraft.com/

Laminar flow airfoils are not new. The P-51 in the early 1940's had the laminar flow NAA/NACA 45-100. I reject the off hand comment that they used what ever NACA threw out. They had the Clark Y before. I have read some of the old dead "sea scrolls" of Aerodynamic days gone by. Those guys where smart. They may have not had computers but they knew how to use them slide rules. I really don't think it was a willy-nilly reason the 230XX was and is popular. Even the late model Cessna Citations still used the 230XX today. Is it the perfect airfoil handed to us from upon high? No but it seems to work well in the RV and many famous planes. One KEY to the 230XX working well is keeping weight down. Drag does go up quickly at higher lift coefficients. Less weight the better.

Evo airfoil:
The CZ engineer started with the MS(1)-313, but we ran into the same thing everyone else using the new foils did: high pitching moment. We flattened out the aft camber to the limits of the aileron and flap design, and this gave us a foil with an approx 60KT wide trim band......

BTW: Glasair uses the LS(1) or GAW foil; Lancair/Columbia and Cirrus use the NLF foils, again all are modified in the TE area to reduce pitching, and also at the LE (Lancair and Cirrus) to tame the stall to certified limits.

The MS(1)-313 is supposedly about 40% laminar, where the 230XX is about 20%; more attached flow is probably better in just about any case. We haven't seen degradation effects that compromises performance to a large degree -- NASA says it (and other later-designed foils) perform more like the 230XX, or other non-laminar foils, with bugs on the LE.
Carry on!
Mark
Mark in no way am I putting down the Pert-tee (Texas for pretty) Evo wing or its numbers, they speak for them self, its faster. However your comment about filling in the cusp to reduce pitching moment caught my attention, since that lowers life and lowers l/d. Do you fly at a higher angle of attack in cruise than the "sport wing". The Glasair was slower than the QuestAir in part due to lower lift, filling in the cusp lowered lift further. Of course Glasair used a different airfoil than you did. I don't know enough to compare the difference. This goes back to the "NO FREE LUNCH" theory. Yes laminar flow wings have less drag but come with other issues. It's how you handle those issues & mitigate them which determines overall gain/loss.

Here's some experimentals (mostly) w/ laminar & odd ball airfoils:
Swearingen SX-300, NASA NLF(1)-0416
Stoddard-Hamilton Glasair III, NASA GA(W)-2 mod
Evo Wing Rocket, NASA MS(1)-313
Jones White Lightning, NASA 66-215 LINK
Aviat Millenium Swift, NASA NLF(1)-0414F/M1
Mooney 301, NASA NLF(1)-0315 LINK
Neico Lancair 320/360, NASA NLF(1)-0215F
Neico Lancair Columbia 300/400, (root) NASA NLF(2)-0215(H)/(tip) NASA NLF(2)-0215(D)
Wheeler Express, NASA NLF(1)-0215F
Neico Lancair IV, (root) McWilliams RXM5-217/(tip)NACA 64-212 **
Prescott Pusher, NASA NLF(1)-0215F
Sharp/Ericson Nemesis, NASA NLF(1)-0414 mod
Aero Designs Pulsar, NASA MS(1)-0313 mod

** The Lancair IV I think is faster than the Glasair III. Not sure what a McWilliams RXM5-217 is. The NACA 64-212 airfoil is a little infamous (used on BD-5). This airfoil is low-cambered and accounts for low maximum lift coefficient and sharp loss of lift at the stall. It's thickness is 12%. The max thickness is moved aft compared to the 230XX. Why they used it at the wing tip, I'm not sure. The Lancair IV reputation is being a HOT airplane. The SX-300 is a personal favorite of mine, but its approach speed of 105 kts!
 
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I've flown an earlier Harmon "rocket" with its itty-bitty chopped off wings. It was sled-like, not very fast for the installed HP and bled energy like a pig in turns. I was glad to climb back into my 200HP RV4.

After 3 years and 500 hours in my Rocket why am I suddenly surprised to find out my airplane is a pig.

I think it is quite fast for the horsepower, my wings are shorter than an RV but I wouldn't characterize them as itty bitty. If I crank in 60 deg of bank or more it bleeds energy but during normal ops I bank like everyone else and energy loss is no more noticable than any other plane. The energy bleed at higher angles of bank is quite often a useful tool.

The "rocket" I flew would cruise around 230 mph with 260 HP installed. My friends RV4 would cruise about 210 with two fewer cylinders. Power off the Rocket came down faster than it would go up - it roared downhill like a manhole cover on edge. Not my idea of a good time if that happened IFR on top. I just don't have that much trust in these old engines

The rocket does NOT go down faster than it goes up. That statement is pure ****. You just have to know the plane and fly it correctly.

20mph faster is 20mph faster and if that is what you want as a pilot it doesn't matter how you get it. If flown correctly it does not come down like a manhole cover on edge clearly you need more time in a rocket to be able to correctly describe its flight characteristics.

If you do not trust a lycoming IO540 on top IFR you shouldn't trust an IO 360 either. If you cannot safely execute a power off landing when you pop out of an overcast you shouldn't have been up there in the first place. I will gaurantee you my probability of surviving an engine failure in an F1 is the same as surviving one in an RV. You just have to know your airplane, plan your flight, and fly it according to its characteristics.

IMHO the F1's are too pricey. What extra performance you get there is offset by much higher cost to operate (the 550 up front), poor tradeoffs in terms of aerodynamic and propulsive efficiency (exception: the EVO wing), and higher kit costs.

The pricing is obvious. If you cannot afford it do not buy it. If your desire is more speed then there is no offset. Speedd costs its just that simple. Don't like the fuel burn pull the throttle back and fly RV speeds. If you want to go fast in a Rocket you can. With a 4 banger you go slower. Depends on what you want.

plumb the outer wing panels with extra fuel to get outrageous range.

Thats great till you have to pee or turn 60 and arthritis sets in. Any more than 3 hrs in a small plane is pure agony for some of us. Load more fuel than the plane was designed for and it may go down faster than it goes up and may bleed energy like a pig. The price of adding more tankage may well offset the advantages of owning an RV. But I really do not have enough hours in an RV to characterize them.

Have the advantage of industry leading support and a HUGE builders network.

This comment alludes to what I consider an old wives tale. That is most kit manufacterers go belly up and leave the airplane owner with an orphan.

I have had nothing but great support from Team Rocket for many yaers and there is no indication it is going to go away. There isn't a single part on the F1 or Harmon that I cannot make in my shop or buy from Vans or another source. Same goes for my plastic airplane of which only 2 exist. As for the support of a great builders network it is right here on this forum for any plane you choose to build.These guys have helped me and several others builders of non Vans aircraft on multiple occassions.


So if you want an F1 or a Harmon get one if it fits your desires. The F1 is one of the sweetest flying planes in existence and has given me many of the most enjoyable flying hours in my life. They have no unsafe flying characteristics if flown correctly just as in the RVs.

RVs are wonderful planes and if one of them better suits your needs or budget then an RV can't be beat.

If you want to know the negatives about a Rocket ask a Rocket owner not someone who "flew one once".
 
I gave a guy a ride in my Rocket early Saturday morning around the Taylor,TX race course and he said he had the last set of EVO's(and he wasn't giving them up) so this may all be moot. You can buy an EVO for $250K or

you'll have to wait for the EVO II!

What is the EVO II?
 
Milt, I've stayed out of this fray because all the "rocket experts" are not rocket owners. Nuff said.
 
GMCJetPilot

Well you sound like a real Aero guy, I have only stayed in a Holiday-Inn and sat next to a real Areo guy.

20+ years doing this does qualify me to a certain degree. Granted, I only now work as a consultant, not full time but I keep my plate full. Please do not denigrate anyone here.

By the way, planform by far plays the larger role in how a wing performs (a wing is a 3-d shape and an airfoil is a 2-d shape). The aircraft you referenced all have very different planforms, fuselages, etc. Also, I think F1Boss said the Questair design team quickly chose other than a 23XXX section. He's probably right.

Milt

If you do not trust a lycoming IO540 on top IFR you shouldn't trust an IO 360 either.

I would fly on top but not for extended periods over low ceiling/vis. My 10000+ hours has its share of lessons.

Quote:
IMHO the F1's are too pricey. What extra performance you get there is offset by much higher cost to operate (the 550 up front), poor tradeoffs in terms of aerodynamic and propulsive efficiency (exception: the EVO wing), and higher kit costs.

The pricing is obvious. If you cannot afford it do not buy it. If your desire is more speed then there is no offset. Speedd costs its just that simple. Don't like the fuel burn pull the throttle back and fly RV speeds. If you want to go fast in a Rocket you can. With a 4 banger you go slower. Depends on what you want.

"IMHO" means "In my humble opinion." You can attack that all you want. You have yours and I have mine. I do respect yours, hope the reverse is true too.

As for the extra fuel, you'll find those ideas are being implemented and are selling on the market. I'm only reflecting a real-world trend, not something I've done with my own airplane.

As for safely executing a forced landing from an undercast condition, I think many of us would see that as a "worst case" scenario. Glide time after breaking out, glide speed, rate of descent and time to select a landing site all play a role in hopefully getting on the ground safely. Airplanes that don't do the above things as well are going to present the pilot with more difficulty and reduce the chances of a safe landing. This is a point Van has made from the get-go and I think he's right.

As for "industry leading support, and huge builders network", I think Vans Aircraft has set a high standard. I've been a builder/flyer on several projects since 1987. I'm sure the Rocket people do a fine job too. The builders network I refer to is this forum and the many thousands of RV'ers out there who will help you at the drop of a hat. It IS great, and do not see that reality as an old wives tale.

Finally, I really never intended to join a "fray" either. I'm an enthusiastic builder and designer who has a passion for this hobby like the rest of us do. I hope we can keep the commentary constructive, and if critical, keep it respectful.

Fly safe...
 
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Horse Power is the answer

111707019fp9.jpg


111707001rl6.jpg


So are you saying HIS wing is faster than my wing? Or I just need a bit more...:)

111707002ki5.jpg
 
Hey Fellas:
...
Current sit rep: We had to stop dealing with the CZ boys in the spring due to the dollar/euro slide. The currency situation at present allows us to produce parts and QB kits here in the USA again, but the biggest positive aspect of this is that I get to make changes to the Evo wing to further optimize it for cruise flight, and attend to the slightly slower roll rate.

Stay tuned -- I think you all will appreciate the Evo II, both in terms of performance and price. I'm not quite ready to make a formal announcement of the new developments, but we are close....

Carry on!
Mark

Hey Mark, thanks for the update on the supply line issues. Now that you've kinda sorta announced the EVO-II we are all curious. Keep us posted!

Thanks again, Vern
 
Which glides further in an engine out

If you have an engine failure which type will glide further? My time in gliders makes me ask this question. You may come down quicker (which is a disadvantage because you have to think quicker about where your going to land and fitting in there) but how much ground are you covering at the same time?
 
Gliding for $ Dollars $

Altruistic

My 200HP fixed pitch RV4 was a pretty good glider, engine out. The prop was heavily pitched (86" of pitch) so even while windmilling, the airplane did pretty well. Best glide speed was about 65 mph and I remember the sink rate being about 700 fpm. That's easy math: for every minute of flight I'd cover a mile and loose 700 feet. I flew that airplane just under 400 hours, so speak from experience here. In really rough terms, that equates to an L/D of 8:1, to put things in sailplane language.

Also from experience, I know that in propeller driven airplanes gliding engine out, the drag from the windmilling prop can make all the difference in how it glides or does not glide. Airplanes with C/S props generally will go to flat pitch with the engine windmilling. This is like having your car in low gear - the windmilling engine spins faster at low prop pitch angles. Take that effect, couple it to a bigger engine like an IO550, and you have even more windmilling drag.

A seemingly benign Piper Arrow, with an IO360, glides very poorly. I've flown them for years, and I like the airplane, but it'd be tough to find a place to park it in an engine-out glide from 1000' up. Glide speed is faster, like 80 mph, and sink rates are about double what the RV4 would do. In rough terms, the Arrow was only 1/2 as good as my RV4. The Arrow's L/D with these numbers is in the ballpark of 5:1.

Now jump up to sport aircraft with even more cubic inches, bigger props, and smaller, possibly less efficient wings. The whole equation gets shifted. Glide speeds are likely to be faster due to the heavier airplane and less wing to support it. And pushing an 80 inch windmilling prop coupled to 6 cylinders in the descent does extract more energy in the glide equation, alot more. This is what pushes the L/D on these types of airplanes down so far - the greatly increased windmilling drag.

It'd be quite interesting for someone with an F1, HR-II, Questair, SX300, or similar to do some glide tests for us and report the numbers.
 
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I know(wive's tale?) john harmon and ted rutherford flew formation with (HR-II)their engines off one day as a plane flew by and looked over and saw two planes with their props stopped.

rockettxrj2.jpg


sport sized wing and EVO wing
 
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This is CAFE speed

Altruistic

My 200HP fixed pitch RV4 was a pretty good glider, engine out. The prop was heavily pitched (86" of pitch) so even while windmilling, the airplane did pretty well. Best glide speed was about 65 mph and I remember the sink rate being about 700 fpm. That's easy math: for every minute of flight I'd cover a mile and loose 700 feet. .

The Cafe report on the -6A showed that best L/D speed is 106MPH. I'd think that would apply to the -4 as well, no? Also over 11:1 glide ratio..

Regards,
 
Cafe info?

Hey Pierre,

106, wow that seems really fast. Yes, the 4 and 6 should be close with other factors equal (engine/prop and gross weight). I did pretty extensive testing on my 4 and got to know the airplane inside and out, as far as flight characteristics & numbers are concerned. I've got maybe 20 hours in the 6, and it does have a higher sink tendency / a bit more power-on on final than the 4. And I was flying a lightweight O320 fixed pitch 6. Both airplanes have the same overall wingspan, but of course the 6 fuselage is wider, so not as efficient in producing lift across the span compared to the 4. Especially since rectangle planforms extract the greatest lift at the centerline of the airplane, and then the lift distribution falls as you move outboard.

Anyway, 90 in my RV4 was a very fast approach speed, like you might want in a stiff crosswind; enough speed to leave plenty of energy for a wheel landing. 100 was a normal cruise-climb. 106 seems like it would be totally out of the ballpark for anything like a good L/D speed.

Do you have any reference to the CAFE report? I'd sure like to see that.

Thx...
 
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nice metro

nice fairchild i used to work on sewer pipes for a living garrett tpe 331 1100 shaft horsepower sorry to go off track. I think i will stick with light as possible rv8 with 180 horspower.

regards

george
 
Speaking of evil wings

Amusing that a photo of a Metro shows up in a discussion of wing designs. That is the poster child for evil stall behavior. :eek:

John Clark
RV8 N18U "Sunshine"
KSBA
 
Glide...

Hi Bill,
What I brought to the table was the best L/D speed...to go the furthest distance from a given altitude in an engine out scenario, not the final approach speed. During my gliding days, we used minimum sink speed during thermaling, and it was much slower than best L/D speed. I can't tell you if 65 MPH is minimum sink or not. I have on many occasions showed transition students the 105 MPH glide speed in my -6A. An 11:1 glide ratio is way better than the 7:1 you get from Skyhawks and 150's. This is the speed I'd use to go the furthest distance if I need the distance. CAFE's pretty darn good at figuring all this out.

BTW, I use around 75 MPH across the fence in my airplane.

Regards,
 
CAFE report on RV6

Pierre,

Interesting report on the 6A, I just read it. (Thks for the link Kevin) Yes, these guys were on the ball with their test methodology.

The flight test here was done at zero propeller thrust, just as you noted. 106 is reported as best L/D, but with propeller thrust/drag taken out of the equation. So, do we have apples/oranges when comparing the CAFE numbers to an actual engine-out windmilling glide? I think so, how about you?

With a windmilling prop up front, my experience has been the windmill drag at higher speeds degrades the glide pretty badly. In an engine-out situation, it would be the L/D for the airplane with windmilling prop up front that you're dealing with, right?

Anyway, nice exchange of ideas here! Wish I had the sailplane hours you've got: my best gliding experience was the time as a new private pilot I had the engine quit on a 172. :eek: Had 8000 feet to play with that time. :p

Lastly, 70 was a nice number across the fence in my 4. Compares well with your 6.

Happy T-day!!!
 
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The flight test here was done at zero propeller thrust, just as you noted. 106 is reported as best L/D, but with propeller thrust/drag taken out of the equation. So, do we have apples/oranges when comparing the CAFE numbers to an actual engine-out windmilling glide? I think so, how about you?

With a windmilling prop up front, my experience has been the windmill drag at higher speeds degrades the glide pretty badly. In an engine-out situation, it would be the L/D for the airplane with windmilling prop up front that you're dealing with, right?
The prop's windmilling drag would effectively raise the profile drag (The CAFE guys called this parasite drag) vs speed curve. The induced drag vs speed curve would still be in the same place it was. The speed for minimum drag (and best L/D) is found where those two curves cross (unless the addition of the prop windmilling drag has substantially changed the shape of the profile drag curve). If you raise the profile drag curve, the speed at which those two curves cross will decrease.

I expect that if the prop is windmilling following an engine failure, the speed for best L/D would be a few knots lower than it would be with zero thrust. Also, the CAFE best L/D speed is for 1650 lb weight. If the actual weight is lower, the speed for best L/D will be a bit lower.

If you have an engine failure, it is better to be gliding a bit too fast than a bit too slow. The glide performance decreases quite quickly if you get too slow.
 
Right on, Kevin. The windmilling prop can add gobs of drag. Just take the throttle at cruise speed and chop it to idle while running the prop RPM to full increase. That'll give you an idea of the "engine braking" a C/S prop can produce. Its great in formation, but you better have your shoulder harness tight!

By the way your RV8 site is freaking awesome!! Its in my favorites as of NOW.

Not to mention the airplane itself: Exquisite!

Exquisite = "... of rare excellence of production or execution, as works of art or workmanship" - Websters

Fly safe...
 
To all who have contributed to this discussion, this is one of the more interesting I've read on the VAF site. Thanks to all who participated; I always stop to read what Kevin Horton, Bill Wightman, George McQueen, Pierre Smith, and of course, Mark Fredericks have to say. I don't mean to leave anyone out, but you guys always seem to take the time to TRY to get things right and to make best-effort contributions. I, for one, appreciate the trouble you guys always to go to help shine a little light on some of the more esoteric issues associated with our sport.

By the way, wouldn?t it be accurate to say that the EVO wings lower stall speed has at least as much to do with its Fowler flaps as it does with its airfoil, aspect ratio, and span loading?

Now, if someone will just tell me where I can get one of those 210 mph cruise RV-4?s, I might be interested!

Regards,


Lee?
 
EVO vs Sport

Wow...Tom once again is a huge aid to all of us Rocketeers...nice sumation of the EVO/Sport differences. I guess I better not get in a knife fight with an EVO...hadn't thought about the turn rate advantage as applied to ACM...

I have only 100 hours in my Sport and have yet to fly an EVO, but do fly a lot of formation with one... I can't add much to Tom's great sumation, except just to point out a couple of quick things.

1) It amazes me to see how slowly the EVO lands...easily gets off a turn-off earlier than me.

2) We just had the SARL race down here, and the EVOs didn't show an speed advantage over the Sports. HOWEVER, that was a down low sprint race. We normally don't fly crosscountry at 500 ft. Due to the aerodynamics of the higher aspect wing, I am certain it has a big advantage at altitude. It would be interesting to get an EVO and a Sport wing side by side at-say-9,500'. I would be very surprised if the EVO didn't run away from the Sport. (matched airplanes, etc..) Tom could probably talk to this also, as he flies x/c regularly with Wayne, who has one of the fastest Sports around... So..don't take the SARL race numbers out of context!

Either airplane is about as good as it gets...can't go wrong wither way!
 
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I wouldn't count a well flown Sport wing out in a dogfight...you won't just be fighting wing to wing...

If you get my drift!


Lee...
 
I wouldn't count a well flown Sport wing out in a dogfight...you won't just be fighting wing against wing...

If you get my drift!


Lee...
 
Doug Bader

I wouldn't count a well flown Sport wing out in a dogfight...you won't just be fighting wing against wing...

If you get my drift!


Lee...

Hi Lee,
If you haven't read "Reach for the sky" by Brickhill, you really should. It's a story about the best pilot in the RAF during WW2, Doug Bader. He outflew 'em all, with no legs but prostheses!

Regards,
 
Thanks for the heads-up on the book, Pierre! I own and have quite a few biographies and autobiographies of WWII era pilots, Bader is mentioned often! My most recent was an astonishing account of the life of a German Messerschmidt pilot, Heinz Knoke. Holy smokes! 80 victories or something like that, shot down twice in the same day, shot down a P-47 once while on fire, engine out, just before crash landing in a field! Amazing!

You may not remember me, we met when you visited Ridgeland Airport several months ago. I'm building an F1 in my hangar there (dark blue, no engine yet!).

Best wishes,


Lee...
 
I do......

.....remember you well! I also remember my drool on your beautiful Rocket:D

How close are you anyway?

Regards,
 
Not a lot of "visable" progress since you were here last time since I am still waiting on my engine, but I have gotten the canopy mostly done, and most of the wiring and fuel system in. Nothing thru the firewall yet (waiting on the engine to know where to put everything). I the meantime, I have a small crack in one side of the canopy, so I'm trying to finish the rear skirts before I remove and replace the plexiglass. We are thinking we are only a few months away from flying once we get the engine in (probably wishful thinking, I know!).

Regards,


Lee...
 
Kindof a stray thought, I just finished reading this thread start to finish and early on there was talk about the evo wing being heavier because it was built to a design speed that we cant reach with current engines. I'm curious what exactly is the design Vne for the evo wing?
 
EVO wing versus Sport Wing.

I want to build a quick build and am trying to decide between a RV-8, F1 rocket with the sport wing or the F1 evo rocket. I owned a RV-4 and still regret selling it With a 160 hp O-320 and a fixed metal prop. It was almost perfect just needed more power, a constant speed prop and lots of expensive avionics for IFR flight. I want a fast aircraft for long solo cross country travel and occasional IFR.

F1 Evo kit (w/emp) ..Lycoming Config????????????$49720
F1 Evo kit (w/emp)..TCM.IO-550.Config??????????.$50700
F1 Sports QB kit (w emp kit)????????????$44270
RV-8 QuickBuild kit ??????????????????$28105

My son and I are also thinking of doing this same thing - F1 Rocket - mainly because of it's amazing quick build kit compared to the harmon rocket's having to build the RV4 from scratch - I also fly a RV4 and love it - but also would like more speed and more power - once you have a taste for it - you always want more. My climbs at 2000 feet per min - but I would like to do 3000? why not. I do mild sportsman catagory aerobatics in my RV4 and love it. I also would like to do more of that so it sounds like for me the sport wing for sure is what I want. I could tell that new airfoil looked like more of a laminar flow airfoil deisgned to be stable at higher speeds I think. I was astonsihed to see that they say the stall is 4mph slower then the sport wing which is larger by 2Square feet or so - and the AC is 100lb's heavier with the EVO wing as well. Sounds like for you - wanting more of an IFR type of plane - suprised you don't go for a bonanza. Seems like everyone is going for those. Or a nice mooney Bravo. Hey I'm not knocking these rockets I think they are amazing and if you are into - some aerobatics and serious speed and don't mind pumping lots of fuel into it - this is an awesome design. Will be interested to know which you choose. I was suprised that the QB RV8 is so cheap.
 
Just an FYI. This post was from 2007. I may be wrong but I don't even think they make any EVO kits any more
 
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