LM701  STOL N1345L

Building the PegaStol Wings

Why PegaStol?

I've had a lot of people ask me why I decided to use the PegaStol wings instead of the stock Zenith wing.  First let me say that the Zenith 701 wing is a very fine wing which does an admirable job for what it was designed to do.  That is to fly low and slow.  Nothing I say is meant to demean the Zenith product, only to explain my reasoning for using the PegaStol wing. 

When I first got into aviation my desire was to be able to fly in and out of my property.  I have a relatively short field of approximately 700' in length.  I tried gyroplanes, that didn't work.  They just wouldn't get up and out quick enough.

I researched the market and decided to go with a Zenith 801.  I liked the four place idea.   I went ahead and purchased a Subaru 2.5 with a  RFI re-drive.  The output would be about 195 hp at 6000 rpm.  Plenty for the 801.  After more research I found the PegaStol wings.  However, I found out that Dedalius Aviation (PegaStol wing maker), did not make them to fit a 801.  There reasoning was that the market wouldn't support it.

I was totally convinced I wanted PegaStol wings.  My logic was very simple, I want low, slow and fast as possible while still being able to use my field.  The Zenith wings just would not give me the cruise or top speed to make some of the cross country trips I wanted to make.  I felt that a 701 with PegaStol wings would give me the best of all my needs.  And, I really didn't need a four place aircraft.

I sold my redrive and purchased a direct drive for my Subaru.  With my engine using a direct drive and a 64" 3 blade prop,  I will have 110 hp at 3200 rpm, plenty for a 701.

I knew very well my engine was too heavy for the stock 701.  However with the upgrade kit and some additional modifications I felt it would work.  I was determined to use the Subaru primarily because I owned it and the Subaru 2.5 SOHV is probably the best automotive engine for an aircraft application there is.  Running a modern fuel injected automotive engine at the rpm it is designed to run will give me a high performance engine with longivity.

I made several modifications to accommodate the heavier engine.  First I built my engine mount extra strong.  I used 3/4" 4130 tube steel  and attached it to six point to the engine and the airframe using no smaller than 1/4 AN bolts with steel locking nuts.   At the same time I moved the engine to within 1" of the firewall.  That is a full 6.5" closer to the firewall than a Rotax.  The air intake filter is inside the cabin and the radiator in under the belly. 

But the most important improvement was to use the PegaStol wing.  Lets look at the end view of both wings.  Photo credits to Zenith and Dedalius.

Other than the fact of the PegaStol slats retract there are several other notable differences between the two wings.

Notice the PegaStol slats when extended actually drop below the bottom of the wing thus causing more drag when extended than the Zenith wing.  When collapsed the PegaStol slats seat into the leading edge of the wing providing a more aerodynamic leading edge than the Zenith wing.

It should be noted also that the PegaStol slat mechanisms consist of simple rollers and it employs no springs or other mechanical parts.  It is virtually impossible for them to jam.

The PegaStol airfoil is semi-symmetrical giving a more aerodynamic airfoil than the Zenith wing.

The Flaperons are tucked in closer to the wing on the PegaStol wing resulting in  less drag.

The Flaperons which consist of ailerons and flags joined together, are larger on the PegaStol wing.  The ailerons are approximately 10% larger and the flaps are approximately 20% larger.  Which offers more control and better lift than Zenith's wing.

PegaStol wings use extruded struts and do not use jury braces.  They also supply drag decreasing air deflectors at all wing and fuselage mounting points.   Zenith uses tubing for struts with jury braces and does not use air deflectors.

The PegaStol wing is 29' from tip to tip while the Zenith is 27' tip to tip, which translates to over 8 more square feet of surface area for lift with the PegaStol wing.

The Zenith wings starts to taper down toward the fuselage at approximately 11" from the fuselage.  This reduces the airfoil and lessens the lift at that point.  PegaStol does not taper.

The Zenith wing uses 7 ribs per wing and the skin is .016 aluminum.  The PegaStol wing uses 12 ribs and the skin is .020 aluminum.    The up side of this is that the PegaStol wing is much stronger than the Zenith wing and does not have the "beer canning" effect between ribs.  The downside is the PegaStol wing is heavier, however PegaStol does employ much larger lighting holes in it's ribs to reduce the weight as much as possible.

The PegaStol wing cost approximately 10% more than the Zenith wing with a like configuration.  PegaStol does not provide fuel gauges or sending units with their wings. 

I feel like my decision to use the PegaStol wing was a sound logical decision in tune with my goals to fly low and slow while having an improved cruise and top speed.

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