21st century Volksplane?

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patrickrio

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The density altitude climb rate issue is super important for aircraft safety, which is of primary importance if you want to call something a plane for all folks...

I think you need to define some city altitude/temperature extremes folks safely should be able to ascend from as well as some certain high altitude flight paths you want folks to be able to safely fly on hot days. Calculate for 2000 feet above the cities and 3000ft above the flight paths.

So, maybe:

Santa Fe NM(7200ft) so 9200ft at 100F with 400ft climb?
follow I-80 from Sacramento to Reno keeping 3000ft at 100F and 400ft climb capacity?
Maybe follow I-70 from Denver to Grand Junction keeping 3000ft altitude at 100F and 400ft climb? (that one is really mountain flying and maybe beyond most "folks" and you need to fly over loveland ski area/Eisenhower tunnel which would require oxygen I think....)

Edit: I-70 is probably just too extreme to call a flight path for normal people.. You probably need a max altitude of 15,000 to fly it...

Anyway, maybe this is hard but I think a true volksplane needs to handle much higher than just 5000' DA or southwest based pilots are going to get caught with density altitude problems much more than a safe plane for normal folks should.
 
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Vigilant1

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Folks have had a lot of fun building and flying planes that can't safely climb out from Leadville fully loaded when it is 100F.

For the VP21, I'd say just shoot for safe climb rates up to a DA of about 5k ft as a begining. If you actually publish accurate climb specs you'd be far more transparent than many E-AB plans/kit sellers and folks can make their own decision on suitability. Heck, I have some real questions about the published numbers for some certified planes
 

Pops

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Local pilot had his Fisher Koala 202 with a 1/2 VW at 10K.
 

Marc W

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The fact is, we don't generally fly these types of planes when the DA is at its peak. My home airport is at 5200' MSL. I fly early mornings in the summer. Temps in the 60's and 70's mean DA's in the 6000'-7500' range. Thermal activity and wind pick up in late morning and it isn't fun to fly a light airplane in that.

I think an honest climb of 300 fpm at a DA of 7000' would serve most locations.
 

patrickrio

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Folks have had a lot of fun building and flying planes that can't safely climb out from Leadville fully loaded when it is 100F.

For the VP21, I'd say just shoot for safe climb rates up to a DA of about 5k ft as a begining. If you actually publish accurate climb specs you'd be far more transparent than many E-AB plans/kit sellers and folks can make their own decision on suitability. Heck, I have some real questions about the published numbers for some certified planes
I think Leadville airport is a full on mountain flying situation like following I-70 would be. After thinking about it, you shouldn't fly that particular area without mountain training anyway. Someone who has that training is going to be competent enough (hopefully) to make appropriate go/no go decisions from Leadville and is better prepared than the lowest common denominator regular pilot a modernized volksplane needs to accommodate.

But following I-80 Sacremento to Reno is more realistic of an extreme flight for a normally prepared pilot. So Donner Pass is at 7200ft so lets say 10,000ft, 95F while still having 400ft climb to be safe from downdrafts? That would be a density altitude of around 15,000ft. Still pretty extreme. Im sure it would be some pretty rough air on that flightpath.
 
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Vigilant1

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I think Leadville airport is a full on mountain flying situation like following I-70 would be. After thinking about it, you shouldn't fly that particular area without mountain training anyway. Someone who has that training is going to be competent enough (hopefully) to make appropriate go/no go decisions from Leadville and is better prepared than the lowest common denominator regular pilot a modernized volksplane needs to accommodate.

But following I-80 Sacremento to Reno is more realistic of an extreme flight for a normally prepared pilot. So Donner Pass is at 7200ft so lets say 10,000ft, 95F while still having 400ft climb to be safe from downdrafts? That would be a density altitude of around 15,000ft. Still pretty extreme. Im sure it would be some pretty rough air on that flightpath.
What are we trying to accomplish? A loaded C-152 can't do that.
 

Topaz

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... But following I-80 Sacremento to Reno is more realistic of an extreme flight for a normally prepared pilot. So Donner Pass is at 7200ft so lets say 10,000ft, 95F while still having 400ft climb to be safe from downdrafts? That would be a density altitude of around 15,000ft. Still pretty extreme. Im sure it would be some pretty rough air on that flightpath.
Obviously we can write any climb specification we want, but there has to be some realistic consideration for the rest of the requirements, too.

Pushing climb that far is going to require much more engine or much more span than the rest of the use-case for this airplane. Is distorting the cost or trailerability (hangarability) of the airplane that much worth attaining this unusual use-case? Clearly it is for your common usage, but for everyone else?

Designing an airplane is a balance of conflicting requirements. A specialized "mountain" airplane won't be as useful for another guy who only has to deal with 2,000' MSL (geographic altitude) airports on hot summer days (5k DA), let alone the guy whose airport is regularly much closer to the ISO standard day.

My impression is that Matthew has more of a "regular everyday" airplane in mind, but I could be wrong.
 

Bigshu

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I thought the Zenith's wing with it's slanted tip was the acceptable compromise between square end and round end. relatively easy to build,too.
That's very similar to the Hummel designs, which are very easy to build.
 

cluttonfred

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I am glad that this is a friendly discussion and nobody is getting bent out of shape. I would say that, like almost any other aspect of aircraft design, there is continuum of solutions from crude and easy to refined and complicated, and different people will fall at different points on that scale in terms of design decisions. You can see that even in something a simple as a MiniMax by comparing an open cockpit 1100R vs. an EROS model with all the bells and whistles (split axle gear, full canopy and turtledeck, rounded wingtips, pressure cowl, wheel pants, etc.). If VB wants raked tips, that's just fine, I just don't think it's worth it in this application.

1625691988478.png VS. 1625692163163.png

On the constraints of stall speed, gross weight, etc., back when we began this discussion years ago the choice in my mind was between two options, European microlight or U.S. LSA, but now I have a third option:

European microlightRevised French microlightU.S. light sport
Gross weight450 kg/992 lb
(472.5 kg/1042 lb with a
ballistic parachute)
500 kg/1102 lb
(525 kg/1157 lb with a
ballistic parachute)
600 kg/1320 lb
Minimum speed65 kph/40 mph/35 knots (flaps allowed)70 kph/44 mph/38 kt
(flaps allowed)
83 kph/51 mph/45 kt

The revised French rules (2019) also specify maximum empty weight of 312.5 kg/689 lb (337.5 kg/744 lb with a ballistic parachute). I have always leaned more toward the microlight category as I think that's where a VW works best but the weights were tough for two modern adults. These new French numbers work much better and keep you from using all the LSA weight allowance and would still, I think, allow the option of a lighter variant with flaps for the countries that still follow the original microlight rules.
 

Victor Bravo

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(hiding in a Kevlar-lined and lead-wrapped bunker, shivering) So can we talk about the VP-1 and VP-2 replacements as VP-21 and VP-22? I'm one of the people who was most intrigued and motivated by the modern take on the intention of the VP-1, not the VP-2. A cheap-enough, single-place, easy to build little near-minimalist runabout. Other people, including the OP, were more interested in the 2-place, and keeping the Bug motor.
 

Topaz

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(hiding in a Kevlar-lined and lead-wrapped bunker, shivering) So can we talk about the VP-1 and VP-2 replacements as VP-21 and VP-22? I'm one of the people who was most intrigued and motivated by the modern take on the intention of the VP-1, not the VP-2. A cheap-enough, single-place, easy to build little near-minimalist runabout. Other people, including the OP, were more interested in the 2-place, and keeping the Bug motor.
Start a thread. I'm sure there's plenty of interest in that topic, and it's likely to live a long and fruitful life.
 

cluttonfred

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The 21 in VP-21 was for 21st century, so how about VP-1-21 and VP-2-21?

And on the VP-1-21 (if we call it that), I would first suggest choosing a baseline engine. Not that other engines can’t be options, but there are just too many variables if there isn’t a baseline powerplant to focus the discussion.

Off the top of my head, the 993cc Briggs & Stratton Vanguard (35-40 hp depending on model) and an Ace Aviation redrive seems like a good option at about $4,000 all in brand new. Pick the middle model at 37 hp @ 3,600 rpm and the Ace ratio of 1.8 and you’ve got a nice prop rpm of just 2,000.
 
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Victor Bravo

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The 21 in VP-21 was for 21st century, so how about VP-1-21 and VP-2-21?

And on the VP-1-21 (if we call it that), I would first suggest choosing a baseline engine. Not that other engines can’t be options, but there are just too many variables if there isn’t a baseline powerplant to focus the discussion.

Off the top of my head, the 993cc Briggs & Stratton Vanguard (35-40 hp depending on model) and an Ace Aviation redrive seems like a good option at about $4,000 all in brand new.
I might just give that a try this evening....
 

Riggerrob

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The 21 in VP-21 was for 21st century, so how about VP-1-21 and VP-2-21?

And on the VP-1-21 (if we call it that), I would first suggest choosing a baseline engine. Not that other engines can’t be options, but there are just too many variables if there isn’t a baseline powerplant to focus the discussion.

Off the top of my head, the 993cc Briggs & Stratton Vanguard (35-40 hp depending on model) and an Ace Aviation redrive seems like a good option at about $4,000 all in brand new. Pick the middle model at 37 hp @ 3,600 rpm and the Ace ratio of 1.8 and you’ve got a nice prop rpm of just 2,000.
Yes, Definitley stick with a modern engine producing about the same power as an early VW conversion ... say 40 horsepower.
 

Bigshu

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Re-reading Pazmany's "Light Airplane Design", I was thinking about his comparison of the different common building materials, and how much lighter aluminum is than wood, or even tube and fabric. It's the more common material in the designs of various manufacturers, and it's something you can learn to work with common tools in pretty short order. Plus, you'll find people willing to pull or pound a rivet easier than you can gluing wood or doping fabric, much less welding. It seems to me that for a 21st century VP, we ought to go with aluminum. The Thatcher designs allow us to have a single seater, tandem two seater, or side by side two seater, with VW power, scratch built for as they say "under 20 grand engine included". I don't know that you can do much better than that these days, since wood has gone crazy price wise. You could probably cut it some with scrounging up a used engine and such. Maybe find an orphan project to complete. I think those designs are well thought out, and seem to be well received by the press and public. I don't own any Thatcher plans or have a stake in their success!
 

Vigilant1

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Don't use the liter V-twins, they're too heavy for graceful flight.
They are heavy. But the lighter V-twins are reliably powering single seat aircraft in direct drive every day. Widely available, about $43 per HP in stock form, some modifications needed to fly an airplane with them.
 
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