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Thread: GFC - What is wrong with this picture?

  1. #1

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    GFC - What is wrong with this picture?

    The official GFC results are now available in spreadsheet form. Here are some of my initial concerns. What is your reaction?
    http://blog.cafefoundation.org/?p=4679

    1. The aircraft weights are not given.
    2. The distance numbers are confusing - wasn't it supposed to be a minimum of 200 miles for each run?
    3. The "distance for speed" numbers for all contestants are less than 200 miles.
    4. The Phoenix and the Embry-Riddle flew the economy leg at nowhere near 100 mph? Why?
    5. The Phoenix only got 55 ePMPG on the speed run at 137.5 mph. That's 27.5 mpg for the airplane. That is about 5 gph at 119.5 KTAS. I can do that in my RV-7A. This number seems way too low. CAFE tested an RV-9A at over 30 mpg.
    6. The Embry-Riddle speed run was at 83.5 mph and got only 32.5 airplane mpg. That's so slow it's below the best speed for L/D for many GA airplanes. If a Van's 7A flies 110 mph it should be able to get 27.7 airplane mpg (using factory specs). This is from an airplane with a glide ratio of about 10 whereas the Stemme starts with a ratio of about 50 and then it's diminished somewhat for cooling drag, etc. Of course, the ER airplane weighed more, but we don't know how much more because CAFE did not say.

    I, for one, am very disappointed with NASA and CAFE for how this event was run. They have been secretive all along. The taxpayer's money should be used to advance GA. A free exchange of performance information, simple, factual information, should not be avoided but promoted. CAFE used to do this with their performance reports. I have no idea why the change in basic policy.

    Just my 2 cents. What's yours?

  2. #2
    Pat_Panzera's Avatar
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    > GFC - What is wrong with this picture?
    >
    > The official GFC results are now available in spreadsheet form. Here are some of my initial concerns. What is your reaction?
    > http://blog.cafefoundation.org/?p=4679
    >
    > The aircraft weights are not given.
    >

    CAFE has been very "closed door" with virtually everything they did.

    > The distance numbers are confusing - wasn't it supposed to be a minimum of 200 miles for each run?
    >

    Yes.

    > The "distance for speed" numbers for all contestants are less than 200 miles.
    > The Phoenix and the Embry-Riddle flew the economy leg at nowhere near 100 mph? Why?
    >

    Neither participant was in it to win it.
    Embry-Riddle was disqualified for not having two persons in the cockpit.
    Phoenix knew they didn't stand a chance so they went for max endurance, and max fun.

    > The Phoenix only got 55 ePMPG on the speed run at 137.5 mph. That's 27.5 mpg for the airplane. That is about 5 gph at 119.5 KTAS. I can do that in my RV-7A. This number seems way too low. CAFE tested an RV-9A at over 30 mpg.
    >

    The little Rotax is not the gas miser some claim it to be. You need to burn fuel to make power. If you are "sipping fuel" you ain't making power. Period. The Phoenix makes a lot of drag at high speed- it has too much wing. They flew the speed-run WOT with no concern for economy.


    > The Embry-Riddle speed run was at 83.5 mph and got only 32.5 airplane mpg. That's so slow it's below the best speed for L/D for many GA airplanes. If a Van's 7A flies 110 mph it should be able to get 27.7 airplane mpg (using factory specs). This is from an airplane with a glide ratio of about 10 whereas the Stemme starts with a ratio of about 50 and then it's diminished somewhat for cooling drag, etc. Of course, the ER airplane weighed more, but we don't know how much more because CAFE did not say.
    >

    The ER plane had a flawed PSRU design that may have been limiting power output. They chose to run three V-belts as opposed to a single cog-belt, and had to balance power with slippage. They said that the TBO on the set of belts is FIVE hours.

    > I, for one, am very disappointed with NASA and CAFE for how this event was run. They have been secretive all along. The taxpayer's money should be used to advance GA. A free exchange of performance information, simple, factual information, should not be avoided but promoted. CAFE used to do this with their performance reports. I have no idea why the change in basic policy.
    >
    > Just my 2 cents. What's yours?
    >

    I'll torque off too many people if I say what I really think. So maybe give me a call.
    All in all I was pleased with the event. It was not an easy task they undertook and I think CAFE overburdened themselves with self-imposed bureaucracy. If they would have had more than the two actual contestants competing, they would not have had enough time to complete the challenge. I know that EAA could have done a WAY better job of handling it, and NASA (and the tax-payers) would have received WAY more value for their investment, if nothing else, by way of positive press. Media was tolerated, not welcomed. In general, we were treated more like competition (by policy) than part of the team, although the individual volunteers were wonderfully accommodating- but they had to bend the rules to do so.

    But I honestly believe that everyone would have been better-served if this had been a design contest, with the top 10 each getting $100k to develop an aircraft that they would compete with a year later. Or maybe top 5 each getting $200k for the same purpose. I also feel that the designs had to be marketable- not a Frankenstein that no one would ever want to emulate or own.

    Look at the number of promising designs that had to drop-out due to the lack of funding. Do you think a $100k shot in the arm could have made the difference? I do.

    Pat

  3. #3

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    Agree with Pat.
    There should have been separate categories. Such as one seat, two seat and four seat. A single-seater cannot compete against a two or four seater fairly because of the seat-miles per gallon formula that favors more seats.

    Also the electric should have a separate category. The formula favored electric by a 3 to 1 margin because electric motors use the energy 3 times more efficiently.
    It is no surprise that a $500,000 electric four seat monster filled with expensive batteries was the winner.

    I had considered a possible entry (practical one seater with gas power), but quickly determined that a one seat entry would have no chance.
    Bill

  4. #4

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    Pat ... bravo. :-)

    I'd love to hear what you really think (or thought.) I love the idea of EAA design / build /fly challenges. After all, we are the experts. I especially like the idea of more numerous, smaller, prizes to help complete several distinct good designs.

    It's odd that GFC went down this way when you consider that NASA has been doing stage 1/ stage 2/ type grants for decades and presumably knows how to get nascent technology to bloom. It's almost as if someone behind the scenes wants another round-the-world autonomous aircraft on the cheap ...
    Richard Johnson, EAA #395588

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