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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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 Posted: Tue Sep 06, 2011 5:57 am Post subject: Success at last |
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As I told Ken last night, for the first time I was able to enjoy flying his plane. As you can see by the pictures the original builder (OB) put rivets on the camber of the ribs. 300+ rivets. It was a job removing them, repairing the tapes around the area, and patching the holes caused when the drill spun off as the head. I still have to put on new tapes on, but last night the weather was so nice I just couldn't wait. At first I was disappointed, there was still some pressure on the stick during climbout, but not as much, and for the first time I could feel a real difference when I pulled on more trim. At any rate, it felt good enough that I decided to climb up to 3000' AGL and try some stalls. It was when I pulled the power back the pressure on the stick lessened. I put off stall testing to investigate and found that at 4700 rpm the Mk IIIX would fly straight and level hands off. At 4000 rpm and below there was back pressure on the stick, i.e. I had to push forward on it.
Stall, power off, occurred at 53 mph IAS confirming that the airspeed indicator is extremely optimistic. It still has a roll off, rather than breaking straight ahead. I didn't try departure stalls or stalls with flaps.
Clearly there is still work to be done. One thing that the OB didn't do, which I believe would help both stall handling and power on balance, is to cover the frame below the engine mount. It's covered on my airplane and on every Mk III for which I've been able to see this area so that will be done before the next test flight. The cap on the top of the windshield still needs to be made.
Since the stick pressure is directly related to power settings, there is the option to lower the engine as far as it will go, but that will require getting the prop blades shortened for boom clearance. Fortunately that can be tested with the prop off my plane first to make sure there is not a serious performance degradation (Ken's prop is a 70", mine is a 66").
So we're not there, yet, but we're past a major hurdle.
Rick Girard
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
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Thom Riddle
Joined: 10 Jan 2006
Posts: 1597
Location: Buffalo, NY, USA (9G0)
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| Posted: Tue Sep 06, 2011 6:52 am Post subject: Success at last |
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Rick,
Glad you are making progress. After all the efforts to fix the lawn dart tendency, can you tell us which one or combination of fixes (OB errors) resulted in the big advance? I don't doubt you mentioned it before but I just don't remember which of the problem resolutions was the big one.
Thom in Buffalo
On Tue, Sep 6, 2011 at 9:53 AM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
[quote]As I told Ken last night, for the first time I was able to enjoy flying his plane. As you can see by the pictures the original builder (OB) put rivets on the camber of the ribs. 300+ rivets. It was a job removing them, repairing the tapes around the area, and patching the holes caused when the drill spun off as the head. I still have to put on new tapes on, but last night the weather was so nice I just couldn't wait. At first I was disappointed, there was still some pressure on the stick during climbout, but not as much, and for the first time I could feel a real difference when I pulled on more trim. At any rate, it felt good enough that I decided to climb up to 3000' AGL and try some stalls. It was when I pulled the power back the pressure on the stick lessened. I put off stall testing to investigate and found that at 4700 rpm the Mk IIIX would fly straight and level hands off. At 4000 rpm and below there was back pressure on the stick, i.e. I had to push forward on it.
Stall, power off, occurred at 53 mph IAS confirming that the airspeed indicator is extremely optimistic. It still has a roll off, rather than breaking straight ahead. I didn't try departure stalls or stalls with flaps.
Clearly there is still work to be done. One thing that the OB didn't do, which I believe would help both stall handling and power on balance, is to cover the frame below the engine mount. It's covered on my airplane and on every Mk III for which I've been able to see this area so that will be done before the next test flight. The cap on the top of the windshield still needs to be made.
Since the stick pressure is directly related to power settings, there is the option to lower the engine as far as it will go, but that will require getting the prop blades shortened for boom clearance. Fortunately that can be tested with the prop off my plane first to make sure there is not a serious performance degradation (Ken's prop is a 70", mine is a 66").
So we're not there, yet, but we're past a major hurdle.
Rick Girard
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
[b]
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_________________
Thom Riddle
Buffalo, NY (9G0)
Don't worry about old age... it doesn't last very long.
- Anonymous |
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rickofudall
Joined: 19 Sep 2009
Posts: 1392
Location: Udall, KS, USA
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| Posted: Tue Sep 06, 2011 9:40 am Post subject: Success at last |
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Thom, I think the top two were resetting the angle of incidence of the wings and removing the rivets.One other project that needs to be done is to add some stiffening ribs to the upper, inside surface of the nose cone. Next time I fly I'll try to get a good picture of just how much it caves in. I've told Ken that if it were my airplane I would make a new nose that would be shorter and more rounded, especially on the sides.
Rick
On Tue, Sep 6, 2011 at 9:49 AM, Thom Riddle <riddletr(at)gmail.com (riddletr(at)gmail.com)> wrote:
| Quote: | Rick,
Glad you are making progress. After all the efforts to fix the lawn dart tendency, can you tell us which one or combination of fixes (OB errors) resulted in the big advance? I don't doubt you mentioned it before but I just don't remember which of the problem resolutions was the big one.
Thom in Buffalo
On Tue, Sep 6, 2011 at 9:53 AM, Richard Girard <aslsa.rng(at)gmail.com (aslsa.rng(at)gmail.com)> wrote:
| Quote: | As I told Ken last night, for the first time I was able to enjoy flying his plane. As you can see by the pictures the original builder (OB) put rivets on the camber of the ribs. 300+ rivets. It was a job removing them, repairing the tapes around the area, and patching the holes caused when the drill spun off as the head. I still have to put on new tapes on, but last night the weather was so nice I just couldn't wait. At first I was disappointed, there was still some pressure on the stick during climbout, but not as much, and for the first time I could feel a real difference when I pulled on more trim. At any rate, it felt good enough that I decided to climb up to 3000' AGL and try some stalls. It was when I pulled the power back the pressure on the stick lessened. I put off stall testing to investigate and found that at 4700 rpm the Mk IIIX would fly straight and level hands off. At 4000 rpm and below there was back pressure on the stick, i.e. I had to push forward on it.
Stall, power off, occurred at 53 mph IAS confirming that the airspeed indicator is extremely optimistic. It still has a roll off, rather than breaking straight ahead. I didn't try departure stalls or stalls with flaps.
Clearly there is still work to be done. One thing that the OB didn't do, which I believe would help both stall handling and power on balance, is to cover the frame below the engine mount. It's covered on my airplane and on every Mk III for which I've been able to see this area so that will be done before the next test flight. The cap on the top of the windshield still needs to be made.
Since the stick pressure is directly related to power settings, there is the option to lower the engine as far as it will go, but that will require getting the prop blades shortened for boom clearance. Fortunately that can be tested with the prop off my plane first to make sure there is not a serious performance degradation (Ken's prop is a 70", mine is a 66").
So we're not there, yet, but we're past a major hurdle.
Rick Girard
--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
get="_blank">http://www.matronics.com/Navigator?Kolb-List
tp://forums.matronics.com
_blank">http://www.matronics.com/contribution
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--
Zulu Delta
Mk IIIC
Thanks, Homer GBYM
It isn't necessary to have relatives in Kansas City in order to be unhappy.
- Groucho Marx
[quote][b]
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_________________
The smallest miracle right in front of you is enough to make you happy.... |
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