When we first began working with our engineers, we broke down our design specifications into two major groups: Requirements and Goals.

Simply put, requirements were items that had to be included or specs that had to be met.  Conversely, goals were things that we felt would be nice to have, or things that were "cool" but could be costly or heavy.

Below are the edited and annotated program requirements and goals, with a little commentary at the end.
Requirements:

  • Aircraft is safe in all flight regimes
  • So far, so good.  Flight testing to date has not revealed any bad habits or unsatisfactory flight characteristics.

  • 2 seats, in tandem, with rear occupant elevated for good visibility
  • Done.  The rear occupant (spouse, father, mother, brother, sister, best buddy or student) is elevated above the front seater by about 8.5 inches (22 cm).  It is a really good view.

  • Twin boom pusher configuration
  • Done.  It isn't the easiest configuration in the world to engineer and build, but it does allow for that great pusher visibility and it looks very sexy (and you'll look sexy flying it, won't you?)

  • Interchangeable wing sets for cross-country flight versus slow sightseeing flight
  • Done.  You can buy one or both sets of wings, depending on your personal desires.  The cruise wings give you some extra knots of cross country speed, but their stall speed will be above the LSA limit--if that's important to you, stick with the slow wings.

  • Aircraft is LSA compliant
  • Done, if the slow wings are used.

  • Minimum of 20 gallons of fuel (safe stowage)
  • Done.  Fuel tanks are in the wing roots and the current  capacity is 24 gallons.

  • Aircraft can be easily put in an enclosed trailer
  • Just don't. We did make the wings removeable, but the whole trailering thing revealed itself to be a rabbit hole.  There's a whole section on it below.

  • Capable of basic aerobatics, with 4.4 G's positive and 2.2 G's negative
  • Done.  There are folks who wanted full aerobatic category G loading, but frankly it's really expensive to engineer and build a plane to those specs without sacrificing something else.  We did a survey of our existing customer pool and it scored low as a priority.  PLEASE NOTE that although the plane is technically capable of basic aerobatics, it's not an aerobat by any means.  If that's a big deal for you, you're probably more interested in a different plane.

  • Capable of safe flight with engines within an 80-125 HP range
  • We have dropped all pretense of flying this thing on anything under 100 HP.  Once you see it in person, the plane is physically pretty large.  Two big people on a hot day with full fuel on 80 HP is a bad idea.  We want to see you have at least 100 HP to stay out of the trees.

  • Provision for mounting a ballistic recovery chute
  • Done.  It can be mounted to the front of the firewall, behind the rear occupant.

  • Provision for cockpit heat
  • Done.  Not a big deal.

  • Provision for wheel pants & retractable landing gear option
  • This has been rethought.  First off, retracts don't give you much better performance than a well-faired gear set.  They weigh a lot.  They have a lot of moving parts.  They make your insurance go up quite a bit.  The new thinking is that we may eventually offer nose-gear retraction and the mains will stay fixed--exactly like the Rutan EZ's.  Getting the nose gear out of the way will give a decent drag reduction without too much weight, and the insurance isn't bad because you won't kill your prop and engine if you do a wheels-up.  Keep in mind that the LSA rules specifically DO NOT allow retractable gear.


And now for an opinion on trailers and all the bad ideas therein :

There is one key thing about trailerable planes that isn't widely acknowledged--most people never trailer their planes anywhere. They're just parked at the airport. In a hangar. Like all the other airplanes.

Yes, many of us know someone who trailers their plane all over the place, but that person is in the tiny minority. Most folks who talk about putting their plane in a trailer really want to so they don't have to pay rent on a hangar, not because they want to drive it around.  But in the grand scheme of things hangar rent is a relatively small percentage of the annual cost of owing a plane, and when it comes down to it trailers are terrible hangars.

At our home airport there are several planes that have folding wings.  Nice mechanism, easy to do.  Pull one pin and fold the wing back.  We've asked the guys who own them when the last time they actually folded the wings back, and the answer was, "never."

Removable wings and folding wings to fit in a trailer or to take up less hangar space are one of those things that looks great on paper and then disappears in the light of day.  Our advice--let it go.
Goals:

  • Take off roll of approximately 500 feet or less
  • It's closer to 750 depending on the day.  This only holds true for hard surface runways . . . grass has a higher rolling friction.

  • Wings should be attachable / removable without tools by one person in 10 minutes or less
  • Done, although you do need a socket.  We copied a common pin-and-fork mechanism that has been around on sailplanes for decades.  Although you CAN do it by yourself, you SHOULDN'T.  Why not?  Because sooner or later you will drop one of your wings.  They don't weigh much, but they are fairly big and awkward.

  • Build time of 150 hours or less
  • Not going to make it.  It was a lofty goal, but it just isn't in the cards.  We estimate that a person with reasonable skills can do it in 500-600 hours and a total beginner in about 600-700 hours.  We have made arrangements with one of our contractors to provide classes on some of the skills you might not already have.

  • Climb rate of 1,250 FPM or greater with 100 HP engine
  • We have climbed the prototype as hard as 1,700 FPM, although that was lightly loaded and a cold day.  Weight and prop pitch are, of course, the two biggest variables.  In a high/hot/humid/heavy condition it is reasonable to assume a climb only slightly in excess of 1,000 FPM whereas a cold/dry day with a climb pitched prop will climb like crazy.
Design Goals
The contents of this web site are wholly owned by Vulcan AeroForge LLC, d/b/a Ion Aircraft.
"Ion Aircraft" is a registered trademark.
Copyright, Vulcan AeroForge LLC.
All rights reserved.  We mean it.