Short span gliders? (Motorglider)

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BBerson

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I was thinking about the smallest practical fun glider and remembering the old contest winning 36' span "Screaming Wiener" https://en.m.wikipedia.org/wiki/Crown_City_Glider_Club_Screaming_Wiener.
It must have been highly maneuverable and fun to fly. Much easier to build and own a smaller size.

So then imagine a small glider with an engine. It could be even smaller because who cares what the glide ratio is when you have an engine? The purpose would be just to climb high and glide down doing loops and whatever between clouds and then landing unpowered. No soaring normally, unless strong lift.

So say about 30'-32' span (or less?) with a VW engine. Say 90-100 sq. ft. In other words, a smaller and lighter RF-3, for example.
Any other motor gliders like that?
 

jedi

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I was thinking about the smallest practical fun glider and remembering the old contest winning 36' span "Screaming Wiener" https://en.m.wikipedia.org/wiki/Crown_City_Glider_Club_Screaming_Wiener.
It must have been highly maneuverable and fun to fly. Much easier to build and own a smaller size.

So then imagine a small glider with an engine. It could be even smaller because who cares what the glide ratio is when you have an engine? The purpose would be just to climb high and glide down doing loops and whatever between clouds and then landing unpowered. No soaring normally, unless strong lift.

So say about 30'-32' span (or less?) with a VW engine. Say 90-100 sq. ft. In other words, a smaller and lighter RF-3, for example.
Any other motor gliders like that?
Exactly where I think the sweet spot is.
 

pictsidhe

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Type certified motorgliders need to gross under 850kg and have a span loading of less than 3kg/m2. A 32ft span would be a max 640lb gross. While that is certified, I suspect that the FAA may look to it for guidance on homebuilts. Build it light, you won't need a VW.
 

TFF

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A 30' span RF-5 for light akro would be great. It would be fun to fly at reduced power. Minimum power aerobatics. Coaxing a loop from a dive or a cuban 8 or whatever. Power on enough for slower level flight, but like going down hill on a bike, use the free extra speed for whatever. It would not be pure gliding but what you would have is neutral buoyancy. How long will a VW fly at 50% power on 5 gal of gas? Set the power and see what you can pull off. Down hill then up, around, down again ready to pull off the next trick.
 

BBerson

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A small VW might use about 2 gallons an hour or something just loitering at 80 mph.
Or climbing to 6000 feet might take a gallon for 6 minutes at 1000 fpm. Shut down and glide at 300 fpm for 12 minutes.
 

pictsidhe

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Wing grid supposedly lowers induced drag. I've not worked out how, though. MIT have been playing with it, so it must have a half decent theory behind it.
 

BBerson

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I think the Moni had some quirks. I watched one land, it came in hot because the tail can't be lowered much. The engine might have been an issue. The one I saw was donated to an A&P school.
 

blane.c

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The EMG-6 may be right for you. It is 850LBS gross and 37 foot wingspan if memory serves. Clip the wings and keep it in solo configuration the 650LBS gross more or less should be obtainable. It is configurable with one, two, or three engines. Plans are free internet source.
 

b7gwap

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That lil Wiener/Dogie is cute. Anyone ever make drawings of the prototype?
 

radfordc

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Type certified motorgliders need to gross under 850kg and have a span loading of less than 3kg/m2. A 32ft span would be a max 640lb gross. While that is certified, I suspect that the FAA may look to it for guidance on homebuilts.
I know that the FAA has approved several motor gliders that don't meet the type certified standard for span loading. Some two place ultralights like the Quicksilver MX and Challenger have been approved. Perhaps the most famous one was Rutan's Space Ship One which was originally certified as a motor glider.
 

Victor Bravo

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The Moni is a neat design. Does anyone know why it wasn’t more popular?
BJC
It was popular, but there were issues.

One or two of the early ones with bonded aluminum skins came apart and people got killed. They fixed that with rivets.

The KFM engines would twist off the prop flange in flight under some circumstances, causing some PR problems.

The sailplane monowheel scared or annoyed some pilots, so they came out with conventional and trigear, but that created more drag. The Moni was an interesting design but it was not a good soaring machine as it was, and more wheels and tires didn't help.. So they extended the wings by a bit, which was not enough.

The typical investor/bankruptcy/lawsuit game happened to Monnett like it does to most anyone in the kit business, and the Moni was collateral damage.

The same basic design layout and construction method was kept, the company name was changed, and they addedanother 12 inches to the fuselage width, creating the Sonex series.
 
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BoKu

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I was thinking about the smallest practical fun glider and remembering the old contest winning 36' span "Screaming Wiener" https://en.m.wikipedia.org/wiki/Crown_City_Glider_Club_Screaming_Wiener.
The Weiner was at a VSA gathering at Tehachapi only a couple of years ago; I got a bunch of good photos of it; one of them is in the Wikipedia article:

https://en.wikipedia.org/wiki/Crown_City_Glider_Club_Screaming_Wiener

Dan Rihn was musing about making CNC-cut wood kits for it. I offered to make Grahphlite-based wing spars. Dunno if anything happened on that. There seems to have been an article about this in the Spring 2014 Bungee Cord, but the issue itself is not available online.

It must have been highly maneuverable and fun to fly. Much easier to build and own a smaller size...
My experience is that "highly maneuverable" is valued to the degree it offers tangible utility. I don't say it's not fun, but it probably pales a bit after a few flights. And as being easier to build and own, at the extremes that becomes both irrefutable and irrelevant. Plenty of folks found the Monerai easy to build and own. But almost nobody actually flies them anymore. For all the "400 kits" said to have been delivered, I have only seen one partially-completed example in the wild, and for all the time I have spent at gliderports I have never seen one fly.

So then imagine a small glider with an engine. It could be even smaller because who cares what the glide ratio is when you have an engine? The purpose would be just to climb high and glide down doing loops and whatever between clouds and then landing unpowered. No soaring normally, unless strong lift.
That sounds like fun a time or two, but not anything I'd go to the trouble of building an airplane specifically for. One way of looking at it is that it is not powerful enough to be a fun airplane, and without good enough glide performance to be a fun sailplane.

...So say about 30'-32' span (or less?) with a VW engine...
The VW engine definitely kills it for me. I could see getting decent performance with a 32' span and ~10 aspect ratio. But adding a 200 lb engine installation that barely produces 50 HP doesn't sound like a recipe for fun.

However, along these lines, there is an optimized small glider that I think would be kick-ass fun: An 11m all-carbon glider designed for high-energy winch launch. Picture acceleration on a par with a carrier cat shot, a quick trip to 1200' AGL, a few maneuvers, then an abbreviated pattern and landing. It and a 500hp winch would make a great soaring demonstrator to take on the road. And it would be rugged but docile, so at home the club could use it to give post-solo students a bunch of launch and landing practice.

--Bob K.
 
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Victor Bravo

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However, along these lines, there is an optimized small glider that I think would be kick-ass fun: An 11m all-carbon glider designed for high-energy winch launch. Picture acceleration on a par with a carrier cat shot, a quick trip to 1200' AGL, a few maneuvers, then an abbreviated pattern and landing.
Buettner's "La Pruvo" that he was toying with several years back??? Or are you referring to a new miniature glider built specifcally for this?
 
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