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Aug 17, 2011, 12:58 PM
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Discussion

ZEPPELIN 1.7m "PSP" video and stuff


“Profile Slope Planes” (PSP) have been on my mind for awhile after closely watching indoor ultra light flying and building the last few months. Lightweight, easy to build, economical and good performance seemed very attractive to me for the slope. I wanted to integrate some of the ultra light features in a 68” slope plane primarily a thin quick to build carbon reinforced fuselage plank combined with a high performance lightweight aerobatic airfoil. And I wanted to do it in old school construction with some new school ideas.

The control gear needed to be easily accessible for maintenance and to make the plane look like a tool with minor “fishiness” traits. Something user friendly no muss no fuss. The KISS principle is all over this model. The designed top airspeed for the Zeppelin is around 30mph and is primarily flown in a smaller frame of sky in aerobatic and VTPR modes. The extra large flight control surfaces patterned after ultra light designs is also a feature that really makes the plane come alive at low air speeds and also serve as a safety net when one finds themselves in a nervous situation and or the need to counter an uncomfortable input. Combined with a lightweight airframe it’s my belief these longer chord lengths (39% tapered ailerons) on the flight controls are better to have than not in tight and twisty in your face aerobatics. My flight tests have shown this to be true time after time.

The designed target AUW (all up weight) is 25-28oz on this span. That’s about a 6.5-7oz wing loading. The prototype in the video is 28 and I’m not sure I want to go lighter. 26-28 seems like the sweet spot for this size plane in low lift conditions yet it still maintains a decent larger airspace aerobatic application.

The plane has a superb gentle stall in all Axis and is very user friendly with no bad habits. Flight control adjustability is very effective and can be finely tuned to pilot preference. Rudder authority is very good, will actually perform over 90 degree flat turns without dropping a wing or elevation! Roll rate, well, it’s off the chart when up to speed but even cooler at lower near hover speeds. Pitch ability is very responsive and smooth with its extra large elevator. The flat-spin attempt in the video isn’t that good because I hadn’t set up the elevator proper yet but the plane easily recovered from going way deep back to the slope lip in the light conditions no problem. Finally as we know with all lightweight models it takes some getting used to when attempting full loops inside and outside. Kinetic energy management on the sticks is very important with these lightweight class models whether woodie or foamy.

Overall I’m very pleased with the performance and agility this woodie produces, even more its building ease. The return on the slope is worth the little extra time putting it together IMO. Wing construction is easy with its modified CNC cut SB96V airfoil. No spar is needed the way I have designed it. The fully loaded 68” wing assembly weighs only 11oz! Total fuselage assembly 17oz. This combination makes for a “low mass inertia” component that makes the plane very survivable at the slope. I counted at least a dozen ground hits during a two hour session with no consequence. Of course if you hit super hard it’s going fracture. If the fuselage is the victim it’s an easy fix. Or cut out another set of planks in half a morning and you’ll be flying by mid afternoon when the wind comes up. The carbon reinforced tail-boom has good flexibility extending the carbon reinforced balsa tail feathers lifespan. Also the carbon fiber rudder hinge post is a real plus for survivability. If the wing breaks well, any plane has its hurdles when repairing a broken wing. Inverted landings are not a real concern with this PSP design. You will see a fairly hard kamikaze dive where my thumb slipped in the video resulting in no damage. And finally a nice feature of this model is it will allow one to fly more slope locations with low lift conditions. That’s cool…

More PSP’s are beingdeveloped and builtwith new profiles as we speak.

Woodies are alive and well…

Eric,
SoCal VTPR

ZEPPELIN 1.7m "PSP" (5 min 37 sec)
Last edited by oldscooler; Aug 24, 2011 at 12:20 PM.
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Aug 17, 2011, 05:39 PM
Tobias (aka glider hangaround)
Fluffracka's Avatar
Nice stuff, Eric. It really seem to fly good and agile, will be fun to see what you can get out of it.
Aug 17, 2011, 08:21 PM
Registered User
Any plans or drawings or close up photos coming for this design? Looks interesting.
Aug 17, 2011, 11:46 PM
DWA
DWA
1Corinthians 13:1-8
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Looks like a very good aircraft for VTPR. Outstanding work Eric.

Dave
Aug 18, 2011, 01:15 AM
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Thanks guys...

Dave, it was nice meeting you at the Fermin deal. Lets get together and do some flying when you get back in town.

Here's a couple close up pics of the Zeppelin. No plans at the moment to kit it but depending on interest it could happen. If I do it will have laser cut parts. In the meantime short kits are a possibility with templates for those inclined to scratch'em. Again if enough interest and i find the time.

The other 5 versions need to get built and flown to have some good comparison notes between the fuse profiles. #2 called "Stiction" is on the bench.

Eric
Aug 18, 2011, 09:03 AM
Good, fast or cheap, pick two
robh's Avatar
Yeah, great stuff Eric. She looks great in the air, and as one who likes wood a great deal, it's nice to see! I've been thinking about a light-air sloper for a while - we don't always get blustery conditions here, and you've shown me another alternative to all foam. Following how this evolves closely, and thanks for posting!
Aug 18, 2011, 10:40 AM
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Nice! So the fuse is solid balsa?
Aug 18, 2011, 11:21 AM
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Laminated solid for better twisting and impact resilience. Two 3/16 thick plates laminated with an inner 1/8 thick plate on the bias for a "plywood" effect. Then a 0.200" dia CF tube running full length on the side. The tail boom is surprisingly flexible and being a slow flyer it's not necessary to have a stiff airframe. Flexible is good with slow flying aerobats in light lift/wind conditions for which this is designed.

Eric
Aug 18, 2011, 11:29 AM
FSD
FSD
Definite Flight Risk
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Very graceful Eric...

-P
Latest blog entry: Flow 3.5 Maiden With Aeros
Aug 18, 2011, 12:31 PM
Semper Fidelis
Big Gas's Avatar
Looks like fun Eric. Nice and smooth flying.

I'm really digging those ailerons.
It would be fun to try a mad stab and balanced rudder. Once you do, its hard to go back.
Aug 18, 2011, 02:20 PM
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Thanks Paige & John, the large flight surfaces are nice to have in reserve, need lots of expo to smooth them out plus a light touch. Respectivly though I'm not a fan of the mad flips and flops. I could very well design one up on this ship but it just doesn't trip my trigger. You guys and others do a great job of it already. Maybe somebody will do "mad-zep" someday?

I have a 100" PSP on the bench I'm planning a "half mad" 45 deg up and down stab travel if that's any consolation.

Eric
Aug 18, 2011, 06:13 PM
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Oops I forgot to mention if you didn't notice the credits or other guy flying in this video. CptMike was on the sticks too. Just wanted to make sure it was known. We fly pretty similar after 20 years on the slopes together and we still like eachother. Thanks Mike!

Eric
Aug 19, 2011, 06:22 PM
Abundantly deficient.......
CptMike's Avatar
Great flyer for light lift and more, no doubt. And I gotta say that balsa still does it for me. Nothin' easier than sheeting white foam with balsa skins......a little sanding and shaping and some of the plane gets in you as you get into the plane. Very manueverable too and so light that the occasional ground-plant goes without injury.

Nice work Eric, a simple design with easy to find materials and crazy fun to fly. What else do you want.


M
Aug 19, 2011, 06:42 PM
FSD
FSD
Definite Flight Risk
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Don't you guys fly together all the time?

-P
Latest blog entry: Flow 3.5 Maiden With Aeros
Aug 19, 2011, 06:47 PM
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Yeah Paige, why do you ask?

Eric


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