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Kolb Ultrastar vs Kolb Firefly

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Victor Bravo

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I've never flown the Ka-6, but by long-standing reputation I believe you have it backwards. The Ka-6 is reported to be one of the most delightful, soarable, and usable sailplanes in existence. Hauling the GOAT up a launch hill is more time and cost than hauling the Ka-6 into the air using the same vehicle.

Are there any HBA'ers who can confirm or deny the soarability of the Ka-6 from personal experience?
 

b7gwap

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VB and HW, good points. I’ve often admired and considered getting a nice old Schleicher or Schweizer. I have my PPL-SEL, and it would cost me around $7k-$9k in dues, fees, rentals, tows, instructor to get my glider add-on at the local club. That and about $2500 a year to remain in said club in order to keep current. I think you’re right, there’s a reason a Ka-6 is so cheap, and it’s not the airplane; it’s a regulatory issue as well as a reliance on aerotow in lieu of alternate launch methods
 

cptcliffhanger

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Regarding the group using a modified Kolb for youth glider training: How hard would it be to 'sell' the idea of a wing for this purpose? Lots of structural and operational advantages to the Marske formula. But it doesn't look like an airplane should look. :ermm:

Les king pretty much had this sorted out years ago (mid late '90s as I recall) he called it the primmer and it was Part 103 legal, minimal parts count seemed to perform quite nicely.. got a few pics from a 35mm film camera I took of it in action at Tehatchapi.. pretty cool plane albeit way off topic for this thread.. my apologies..

06.jpg08.jpg18.jpg01.jpg

I always thought it was pretty cool. Les was a clever guy.
 

b7gwap

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I suppose as the OP I’m the one who drifted it, so no worries.

That is a really cool looking glider. Did he make any drawings available?
 

b7gwap

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The stall speed requirement still applies, but of course the max level speed doesn't.
Dana, I got this from the FAA:

This part prescribes rules governing the operation of ultralight vehicles in the United States. For the purposes of this part, an ultralight vehicle is a vehicle that:

(a) Is used or intended to be used for manned operation in the air by a single occupant;

(b) Is used or intended to be used for recreation or sport purposes only;

(c) Does not have any U.S. or foreign airworthiness certificate; and

(d) If unpowered, weighs less than 155 pounds; or

(e) If powered:

(1) Weighs less than 254 pounds empty weight, excluding floats and safety devices which are intended for deployment in a potentially catastrophic situation;

(2) Has a fuel capacity not exceeding 5 U.S. gallons;

(3) Is not capable of more than 55 knots calibrated airspeed at full power in level flight; and

(4) Has a power-off stall speed which does not exceed 24 knots calibrated airspeed.

Is there another document that specifically applies the 24kcas to unpowered UL vehicles? This looks like an “or,” not an “and” thing to me.

Interestingly, this also means gliders don’t get fudge room for emergency equipment or floats like powered ULs do.
 

cptcliffhanger

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I suppose as the OP I’m the one who drifted it, so no worries.

That is a really cool looking glider. Did he make any drawings available?
if there are detailed drawings out there, I'd love to get my hands on them.. I afraid the chances of getting them diminished greatly when he passed away.
 

jedi

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Catching up on the last several posts: Sorry, this is extending the off topic discussions.

At 10,000 (MSL or ASL?) feet you may want the pilot enclosure if you are in FL. In CO or other mountain states you likely will not want the enclosure. It is great to see the tree tops pass by 10 feet below your seat. Much easier to climb in and out also. Did anyone mention weight, no need to clean a windscreen, or other advantages.


Post #17 Stall speed does not apply to unpowered UL. 155 pounds as noted in post # 25 is the only physical limit. Sparrow Hawk is a good UL example.

Post # 21 KA-6 is (or more specifically was) delightful. It is what got me hooked on gliders. By modern standards perhaps not so much.

Post # 23 Henryk where are you? Yes, the wing is the thing. The BKB was designed as an inexpensive club training glider. Plans may be available but old (wood) construction. Do you want that or Aluminum tubes that bolt together (Cascade Ultralight "Kasper wing") or composite (Millennium)? Make me an offer on a Mitchel B-10 complete with flight training.

KA-6 versus Goat. Depends on what you have. Both have enough disadvantages that after a few years the thrill may wear off.

Post # 26 You are a great candidate for Sport Pilot Glider. A few flights and A CFI sign off for another CFIG to do a check flight. Save $500 in DPE fees. Any additional flights are PIC even if you choose to go with the CFI. Take family in a 2-33. Several more flights and go for the commercial glider if you like and let others buy the tow and glider time at many clubs. It can be difficult to find an operation with a light sport equivalent glider. Most glass ships have a Vne over the 127 kt limit.
 
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Topaz

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I've never flown the Ka-6, but by long-standing reputation I believe you have it backwards. The Ka-6 is reported to be one of the most delightful, soarable, and usable sailplanes in existence. Hauling the GOAT up a launch hill is more time and cost than hauling the Ka-6 into the air using the same vehicle.
All true, right up until the moment you don't have a winch, a tow-plane, or local conditions that allow for an auto-tow that isn't consistently a very short sled ride. I happen to know that's pretty much the case for Hot Wings. For him, a Ka-6 would make a really nice paperweight, whereas a GOAT could be workable. I'm sure he's not alone.

Are there any HBA'ers who can confirm or deny the soarability of the Ka-6 from personal experience?
I've never flown one, but Autoreply swears by them. Same impression as you.
 

Hot Wings

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For him, a Ka-6 would make a really nice paperweight, whereas a GOAT could be workable.
If I lived a hundred and a half miles south a KA-6 would be a much more attractive option. But even then I'd have to wait for the weekends......:ermm:

Has anyone ever winch towed a glider fitted with a ski on snow or ice?
 

b7gwap

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Those sustainer motor equipped ULF-1 8mm videos from Sweden on a frozen lake come to mind even though that’s not a winch.

Re: 103 unpowered speeds, really they may as well apply to airchairs. Sandlin’s designs likely stall slower than the powered limit, given the launch technique, and are so draggy they will never approach the maximum in level flight.

I may start another thread about design discussions to make a Goat like glider that does everything the same but incorporates two major changes: A more robust structure using taller spars, and related to this would be ability to scale the wing area to suit pilot mass. Goat aspects i desire to keep: simple fastened structure, car toppable, 103 legal, hill launch to share HG sites.

So far I like the Kolb idea, need to do stress analysis on requirements and see if that design can make weight, but the big advantage of the Sandlin design is maintained here, in that the spar is a manufactured, extruded piece requiring minimal build up for use. It would also simplify the setup and take down of the glider since it would have one wing strut only.

Other ideas I have to maintain the erector set mentality would be a pair of tall and skinny B-17 style truss spars made from .750” or 1” square tubes for caps and verticals and angle for diagonals. Still doing some rough calcs on how much something like that might weigh. http://legendsintheirowntime.com/LiTOT/Content/1944/B17_Av_4402_sk_spars_p139_W.png

Obviously a sheet stock web with square or angle caps could replace the truss above as well. In order to maintain simplicity, pulled rivets or aircraft bolts would be used in any of these buildups, and the weight of hundreds of steel fasteners would have to be considered.

I just want to see if it can be done. My instinct tells me that a tall skinny web at 1/4 chord and at the aileron spar could be made very light, using a thick section to build strength and stiffness. Use aluminum truss ribs as compression struts and internal wire bracing for drag anti drag (as the goat currently uses). Add simple single .250 round tunes for upper surface ribs between compression members like the current goat. Hot wire foam nose ribs and make a thin nose shell out of sheet stock.

Maybe a Lazair type wing would work too. Another advantage of Sandlin’s design is robustness, a not inconsiderable advantage when putting a stack of wing panels on top of a minivan.

Napkin sketches in work. :)

Austin
 
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b7gwap

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Catching up on the last several posts: Sorry, this is extending the off topic discussions.

At 10,000 (MSL or ASL?) feet you may want the pilot enclosure if you are in FL. In CO or other mountain states you likely will not want the enclosure. It is great to see the tree tops pass by 10 feet below your seat. Much easier to climb in and out also. Did anyone mention weight, no need to clean a windscreen, or other advantages.


Post #17 Stall speed does not apply to unpowered UL. 155 pounds as noted in post # 25 is the only physical limit. Sparrow Hawk is a good UL example.

Post # 21 KA-6 is (or more specifically was) delightful. It is what got me hooked on gliders. By modern standards perhaps not so much.

Post # 23 Henryk where are you? Yes, the wing is the thing. The BKB was designed as an inexpensive club training glider. Plans may be available but old (wood) construction. Do you want that or Aluminum tubes that bolt together (Cascade Ultralight "Kasper wing") or composite (Millennium)? Make me an offer on a Mitchel B-10 complete with flight training.

KA-6 versus Goat. Depends on what you have. Both have enough disadvantages that after a few years the thrill may wear off.

Post # 26 You are a great candidate for Sport Pilot Glider. A few flights and A CFI sign off for another CFIG to do a check flight. Save $500 in DPE fees. Any additional flights are PIC even if you choose to go with the CFI. Take family in a 2-33. Several more flights and go for the commercial glider if you like and let others buy the tow and glider time at many clubs. It can be difficult to find an operation with a light sport equivalent glider. Most glass ships have a Vne over the 127 kt limit.
I had completely forgotten Sport Pilot existed, thanks for reminding me. Must a glider qualify as an LSA for this?
 

BJC

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There was someone at AirVenture showing a video of children learning to fly a primary-style glider that was a converted Kolb. Not sure what model it had been before the conversion, but it had a robust roll cage and seat / restraint system that probably helped shift the engineless CG into position.

Anyone have a link to their video?

What would a used Kolb without an engine and propeller cost?

Thanks,


BJC
 

jedi

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I had completely forgotten Sport Pilot existed, thanks for reminding me. Must a glider qualify as an LSA for this?
Yes. See FAR Part 1 paragraph 1.1 General definitions for light-sport aircraft.

Correction: I misspoke earlier LSA max Vne is 120 kts not 127 kts as posted in post # 27 . If the glider is EAB the Vne can be reduced by paperwork as needed to comply. Glider manufactures should use this method to increase glider sales as is typically done with the 1320 pound limit for powered aircraft.

Second correction by edit: Reference EAB comment above. The Vne can be reduced by the owner but it would be disqualified as a LSA by condition #3 and the bold print included below.


Light-sport aircraft means an aircraft, other than a helicopter or powered-lift that, since its original certification, has continued to meet the following:

(1) A maximum takeoff weight of not more than—

(i) 1,320 pounds (600 kilograms) for aircraft not intended for operation on water; or

(ii) 1,430 pounds (650 kilograms) for an aircraft intended for operation on water.

(2) A maximum airspeed in level flight with maximum continuous power (VH) of not more than 120 knots CAS under standard atmospheric conditions at sea level.

(3) A maximum never-exceed speed (VNE) of not more than 120 knots CAS for a glider.

(4) A maximum stalling speed or minimum steady flight speed without the use of lift-enhancing devices (VS1) of not more than 45 knots CAS at the aircraft's maximum certificated takeoff weight and most critical center of gravity.

(5) A maximum seating capacity of no more than two persons, including the pilot.

(6) A single, reciprocating engine, if powered.

(7) A fixed or ground-adjustable propeller if a powered aircraft other than a powered glider.

(8) A fixed or feathering propeller system if a powered glider.

(9) A fixed-pitch, semi-rigid, teetering, two-blade rotor system, if a gyroplane.

(10) A nonpressurized cabin, if equipped with a cabin.

(11) Fixed landing gear, except for an aircraft intended for operation on water or a glider.

(12) Fixed or retractable landing gear, or a hull, for an aircraft intended for operation on water.

(13) Fixed or retractable landing gear for a glider.
 
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jedi

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If I lived a hundred and a half miles south a KA-6 would be a much more attractive option. But even then I'd have to wait for the weekends......:ermm:

Has anyone ever winch towed a glider fitted with a ski on snow or ice?
Don't need a winch. A big lake and a snowmobile will do for a light glider.

Only good for pattern tows anyway. Hard to find good thermals in the wintertime fair weather high.

If you want a lake with adjacent ridge lift look for a glacial moraine and associsted lake. Talk about hard to find flying sites close to home. My example is Blue (?) Mountains in northeastern Or.
 

Hot Wings

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Yes, and "auto"-towed as well. With a big snowmobile. Not me, and I won't say who did. :gig:
Kind of illustrates how hard it is to 'think outside the box' - at least for me. I was just thinking about ways to extend the flying season around here. Hadn't even considered snowmobiles, which are quite plentiful around here. Combining snowmobilers and primary gliders now seems kind of obvious. The snowmobilers are already in place and would/could provide the labor for launching that the traditional club structure offers. And as a bonus we get to introduce flying to a set of recreational enthusiast that might become glider pilots?
 
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