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jim
Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho
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 Posted: Fri Nov 03, 2006 5:22 pm Post subject: New Kolb owner |
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Sorry for the long story, but I hope some will find it entertaining. It is mostly included for background and the amusement of others, but I have a few questions at the end. Thanks in advance.
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I bought a junker 1983 Quicksilver MX last year and got it flying this Spring. I flew it about 35 hours and really enjoyed it but was soon longing for something faster, more stable in turbulence (higher wing loading), and something I could take somewhere. A friend told me about the Firefly, I did some research, and met a guy with one at an EAA flyin. When I saw it and saw it fly, I was SOLD.
I sold my Quicksilver MX and looked around but didn't see many Fireflies for sale. There was a nice one down in TX, but I didn't want to drive 44 hours each way to get it. I found one in San Diego area that sounded good on paper: Factory built (including covering) in 1993, Rotax 503 DCDI, 3-blade ground adjustable IVO prop, 4.5 hours TT airframe & engine, including 1 hour Rotax engine breaking. Full instruments, and enclosed Aluminum trailer for $8000. He told me about a scarf patch on the tail boom and a couple wing patches but he made them sound insignificant.
Unfortunately I was a bit too excited and bought it after little conversation, sight unseen. My wife and I made the 26 hour drive from North Idaho and when I saw it I was a bit disappointed in its condition. I should have renegotiated the price down some, but didn't. The prop had been cut down to 52" and the pitch cranked up all the way. The trailer was home made and kind of funky. He had painted it himself and it looked it. He had mounted the engine; it wasn't unsafe, but it could have been better.
At 1 am and 500 miles into the 1500 mile trip home during thunderstorms, wind, and rain, the right wheel fell off of the trailer. At first I thought the axle broke, but it didn't. He had recently put on new tires and just hadn't tightned the lugs down. Before I drove away from his house I considered checking them, but I have never seen loose lugs before -- usually lugs are put on too tight rather than too lose. Apparently the wheel worked itself loose and ended up pulling off through 3 of the 5 lug nuts. I couldn't get the nuts off the remaining 3 studs, nor did I ever find the tire or wheel. Fortuntely we were only about 6 miles from the nearest town (it could easily have been 30 miles in that area). We got some sleep and with a few parts, grinding, and welding from local stores, we were back on our way 12 hours later.
After I got home I cleaned up the trailer and while still funky, does do the job fairly well. I also washed the Firefly. Washing something is a good way to find all the fabric and other damage. While there were probably 5 polyfiber repairs and it needs 2 more, all are small and only of cosmetic concern.
I looked at the prop some more and realize that the previous owner really screwed up a nice prop by cutting it down to 52". Even so, the prop was 4.5" above the boom. It appears he did not know the Rotax B gearbox could be rotated up because he had it down and the whole engine shimmed up 1" with Aluminum shims. Even though his plate was drilled for it, he did not use Lord mounts to mount the engine, and the aluminum plate was bolted to the cage, not the engine block.
The logbook for the engine showed 5.5 hours of run time, but it appears all entries were filled out with the same pen on the same day. Logbook entries are dated 1997-2004 or 2005.
He obviously had problems starting the engine because it came with a can of ether. He had a choke control and primer system with it. The choke cables were so lose as to be totally innefective. He had a quality GA grade Essex primer on it, but the hoses were crumbling apart.
I replaced some of the fuel line and sealed off the primer lines until I could get the right hose and fittings for it. I also cleaned out the fuel tank and carbs. I flew it twice pretty much as is, but only about 10-20 minutes and 2 landings both times.
The FF always took lots of right aileron to hold the wings level. Clean power off stall was 40mph IAS on the 0-160mph gage. This seems fast considering I was expecting closer to 30mph. Clean p/o stall with full flaps was maybe 2mph less. I tried high cruise (WOT=6000 rpm) but it took almost full forward stick and it still wanted to climb. It also took lots of right stick. Even though my right arm got tired of holding right stick, there was still plenty of right stick available, but it took both arms to do it.
For the 3rd flight I fixed the choke and adjusted the ailerons (this time in the right direction). Aileron forces are MUCH better, but still requires some right stick, especially at high cruise. I did 2 landings on each flight, the first pretty good, the second perfect. I decided to see what kind of power off glide ratio the Kolb Firefly has. At the 180 I pulled power. I thought I was going to be too high but with the wind down the runway and the surprisingly poor L/D glide radio of the FF, I thought I would just make the numbers. On short final (<3 seconds to touchdown) I added a little power and decided that I should drop the flaps (bad decision). I like the way the Kolb handles while landing with full flaps, and I thought it would extend my glide a little. As it turns out it #1 distracted me from looking at the runway, and #2 cause me to slow down even more. Then I rotated a little [too much] to reduce my sink rate. Unfortunately I recognized the situation about 1/4 second too late. I went to full power but stalled and hit hard from 3 feet. As soon as I hit the RPMs kicked in.
I got airborn again but suspected I may have done some damage so I landed right away. I then taxied back to my hanger, and inspected the aircraft. I had bent both gear legs, but could see no other damage. The left gear was bent more than the right. On the right one, the top of the gear leg was straight (i.e., no taper), and the bottom was "straight" with twice the taper. The left gear leg was bent upward in an arc.
I have already ordered two new gear legs from TNK, and will probably try to straighten the right leg for use as a spare (although I don't plan on landing hard again). They probably won't be here until Monday, but it's supposed to rain for 4 days anyway. After that it will probablly hail, snow, and generally stay frozen up here in North Idaho until March.
QUESTIONS
1. Does everybody have their Rotax gearbox in the "UP" position?
I am concerned that the Firefly may be aerodynamically designed to have the gearbox up. This would raise the thrust line and reduce the excessive forward stick needed for high-speed cruise. Or is it good to have the prop as low as possible.
2. Engine mount location
The previous owner installed the Rotax 503 with the aft end of the engine block (not the PTO) flush with the back end of the mounting plate and Lord mount holes. The B gearbox is 2" aft of the plate, and sticks down below it. I wonder if this causes an aft CG condition that is the primary reason for the excessive forward stick needed at high cruise. He may have done this because he does not have the 2.5" Ivo prop spacer I have seen on other Fireflies with the Rotax. If I install the standard Lord mounts, it may move the engine forward to where I will have to buy a spacer.
3. Weight/CG
The previous owner did a weight and balance on the FF. It is 70# over the part 103 weight, but it showed as within CG (I don't remember exactly where it was). There is no BRS or unusual accessories on the aircraft so I am surprised it is so far overweight. It has the short windshield, 4" wheels, drum brakes, and oil injection. The 503 only explains an extra 20# over a 447; the brakes, 3-bladed prop, and instruments maybe another 20#. Is 320# excessive? What is the average weight on the tailwheel for a Firefly? What is the average weight of a "real" Firefly?
4. Does anybody use a short prop?
I hate to fork out $500 for a new IVO 62" 3-bladed prop if I can make the one I have work. It is cranked up to max pitch (I believe) and turns 6000 rpm static AND in flight. Until I bent the gear, my plan was to reduce pitch until max rpm is 6400-6500 rpm. Then I would measure rate of climb and try to get a feel for the performance. Currently, takeoff and initial climb seem OK, but it seems to drop to 500-600 fpm after 500'. I think I should see 1000+ fpm ROC. If I can get to that, I will probably keep the prop I have. But with I 503dcdi on a Firefly, I expect spectacular performance. It's been OK, but certainly not spectacular.
Thanks,
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Jim
N. Idaho |
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Richard Pike
Joined: 09 Jan 2006
Posts: 1671
Location: Blountville, Tennessee
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| Posted: Fri Nov 03, 2006 5:44 pm Post subject: New Kolb owner |
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Graet post! Now for your questions -
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Richard Pike
Kolb MKIII N420P (420ldPoops)
Kingsport, TN 3TN0
Forgiving is tough, being forgiven is wonderful, and God's grace really is amazing. |
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beauford(at)tampabay.rr.c
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| Posted: Sat Nov 04, 2006 9:41 am Post subject: New Kolb owner |
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Jim:
Congrats on the purchase of the Firefly, and welcome to the list.
I think the Fly is a delightful little machine and I am sure you will enjoy
yours, especially
if you can get the weight down closer to where it was designed to be;
around 500 lbs all-up gross. I regularly fly mine at about 515 or 520,
but believe me every extra pound costs you in terms of performance and I
can feel it in mine when I load it over 515... even 10 pounds makes a
substantial difference. A 500 pound Fly pushed by a healthy 447 is a real
rocket ship...
Of most concern to me in what you wrote is the 503 installation. The
steel cage on the stock Fly is manufactured mostly from .028 wall
thickness chromoly... Back in '99, I talked to the factory folks about
cage materials and engineering when I was ordering my kit. The guys at
original Kolb told me that the cage was engineered to be heavy enough to
take the weight and stress of the Rotax 447, but definitely not engines
heavier or more powerful. After talking with them a while, I had the cage
for my airplane built
using thicker .035 tube, even though it
made the cage a couple of pounds heavier. I have discussed the matter of
putting a 503 on my heavier cage airplane with the man who actually
designed and engineered the Firefly... He clearly thinks it is not a
good idea to overstress the structure with the heavier engine, even with
my special-order .035 cage structure. I consider this individual to be
highly competent
and I know for a fact that at Kolb he put a lot of quality engineering and
stress analysis into designing the Firefly cage... remember, the use of
the 447 on a legal UL was a big deal back then...It was considered a BIG
engine for this size and weight airplane. As I recall, this was the first
447 powered design to meet the part 103 requirements.
Anyway, bottom line in all of this is that it might be worth thinking about
the ramifications of a 503 on a stock Fly cage...could be a good idea to
watch it closely for
cracks and deformed structure. And it might also be worth checking on the
issue
of the extra weight of the 503 up there behind
your head on that light .028 structure if you should commit a sudden
stoppage... of the airplane, not the engine... keeping that Rotax off the
back of your neck is the cage's job...skinny cage might just do a skinny
job...
There are some knowledgeable gents on this List who know a lot more about
this
matter than I, sir... and there is most certainly some considerable
expertise at the Kolb
Works on the questions about hanging the bigger motor on it... If nothing
else, the
factory can likely tell you what wall thickness the tubing in your
particular cage might
be if you tell 'em the serial number... Might not be a problem at all... but
phone calls
are cheap and they just might have some insight into this particular
issue... Just a thought...
You mentioned props... the stock Firefly prop size in an IVO 2 blade was
66 inches on the 447 ... gave a little over an inch clearance on the
boom... gearbox up.
Good luck, Sir... Be advised that my advice is worth what ye paid fer it....
Beauford, the Aluminum Butcher of Brandon FL
FF #076
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DAquaNut(at)aol.com
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| Posted: Tue Nov 07, 2006 8:08 pm Post subject: New Kolb owner |
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In a message dated 11/4/2006 11:42:53 A.M. Central Standard Time, beauford(at)tampabay.rr.com writes:
| Quote: | You mentioned props... the stock Firefly prop size in an IVO 2 blade was
66 inches on the 447 ... gave a little over an inch clearance on the
boom... gearbox up.
Good luck, Sir... Be advised that my advice is worth what ye paid fer it....
Beauford, the Aluminum Butcher of Brandon FL
FF #076
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Hi Bill,
Haven't seen You post on the list in a while! Guess you've been busy! I am puzzled how you got over an inch clearance with your 66" Ivo. I have close to 3/4' clearance , but would feel a lot better if I had over an inch!
Ed Diebel FF # 062
[quote][b]
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The BaronVonEvil
Joined: 23 Jun 2006
Posts: 76
Location: Walla Walla, WA.
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jim
Joined: 03 Nov 2006
Posts: 107
Location: N. Idaho
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| Posted: Wed Nov 08, 2006 12:55 pm Post subject: New Kolb owner |
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Thanks for your reply.
I live in Coeur d'Alene, Idaho, but own a lot and have a hangar up at
Hackney Field (ID05) in Athol ID (about 12 nm N of KCOE, Coeur d'Alene
Airport and 1 mile NE of Silverwood theme park). Hackney is a grass strip
about 3500 feet long.
I would definitely like to connect, but I probably won't be making any
cross countries in my Firefly until it warms up in Spring (and I get more
confidence in it). You are welcome to drop by the field any time. If you
can give me some notice I can be up there to give you a tour. With the
colder weather and darkness, I'm generally only up there on weekends now,
Saturday and/or Sunday.
I ordered and received the Lord mounts from TNK and will be putting them
in. The previous owner did have some engine mount dampening, but I am
sure it wasn't as effective as the Lord mounts. He had the 503 raised up
so it will actually drop 1.5 inches or more when I move to the Lord
mounts. That is not a problem for prop clearance to the boom, but if it
goes any lower the wings won't fold so I will have to flip up the gearbox
at the same time. I am hoping I can do this by just removing 4 bolts on
the B-box, and rotating it 180 degrees without a whole bunch of time or
mess involved (leaving the prop on, etc.).
I expect I will be changing to a longer prop before much longer, but I
want to install the Lord mounts, rotate the gearbox, and get it flying
again for some performance testing before I decide for sure. I was going
to go with a 62" 3-bladed ground adjustable ivoprop, but it appears some
folks prefer the 2-bladed. Any comments or recommendations you have on
the subject would be welcome. If you know anyone with a prop for sale,
please let them/me know.
The 4 inches of clearance Ivo recommends is fore-and-aft clearance to
things like the wings and ailerons. This is because at some times the Ivo
will flex forward and back. Of course there is also prop movement up and
down, but this would be caused by the engine moving in it's flexible
mount. Some folks have only 1" clearance between the prop & boom. TNK
recommends 2". I believe 1.5" would be a minimum.
Did you know Powerfin is now in Spokane? I'm not sure when they moved,
but I don't think it was too long ago.
I will also do a weight and balance, but probablly not until next year
after I finish making the changes I need to make (Lord mounts, prop,
moving instruments, etc.)
See ya,
Jim Dunn
cell 509-220-6996
| Quote: |
Hi Jim,
I live here in Walla Walla WA and fly a Kolb Firestar II. What part of
N. Idaho do you call home? I am not aware of many Kolb flyers in the area
and would be happy to meet with you and help in any way I can. You are
welcome to come by and check mine out if you like to try and answer any
questions you might have.
My Firestar has a Rotax 447 with the 2.58 to 1 B gearbox upright. I
believe this is how they are meant to set up. It came with a 66"'x 30p
Tennessee prop and flew well. I have since changed to a powerfin 62"
composite two blade prop and gained a smoother and slightly better
performance.
I believe you will end up changing out the prop on your 503 due to it
being undersize for your engine. I would seriously consider remounting
the engine onto Lord mounts to prevent damage to your airframe before
flying it further. The Lord mounts will also raise the engine about .75"
which will help with the prop clearance over the tail boom
A larger prop will definitely improve your climb rate over the cut down
prop you have now.
On mine at least I have about 2.75" of clearance between the propellor
tips and the aileron tubes. With the IVO's I think the prop needs about
3" of clearance due to the blade flexing.
I would also as a precaution do a compression test of your engine and make
sure it is up to snuff. Starting fluid is BAD NEWS to 2 cycle high
performance engines. If the engine doesnt start easily you are either
doing something wrong or the engine is out of adjustment somehow.
Most important is to run fresh fuel through your engine. Old fuel is
almost as bad as starting fluid.
You should do a weight and balance of the Firefly yourself to verify what
the paper work is saying. It sounds a wee bit phat but you havent
mentioned if you have electric starting or how much other stuff is
actually on the plane. All those little accessories that people add to
their planes can add lots of weight in a hurry.
I hope this helps out. Feel free to email me if you have any questions or
maybe want to get together sometime.
Best Regards 
Carlos Grageda
AKA
The BaronVonEvil
grageda(at)innw.net
Read this topic online here:
http://forums.matronics.com/viewtopic.php?p=72982#72982
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Jim
N. Idaho |
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