Results 1 to 3 of 3

Thread: S-20 with Metal Wing: FLIGHT REPORT

  1. #1
    Administrator Site Admin's Avatar
    Join Date
    Feb 2008

    Default S-20 with Metal Wing: FLIGHT REPORT

    From Randy Schlitter:

    "S-20 (metal wing version) flight testing continues:

    Yesterday we discussed the lack of prompt centering, system friction was suspect. We tweaked it down from 3. 5 pounds to 2. The instant I launched this morning it felt natural and well harmonized. We have already adjusted the soft tooling to make this to not happen in the production parts. Now the ailerons are a blast. The only downer was a left roll with hands off. We knew the wing twist between the pair could be off a few tenths of a degree. This was a lack of experience with this construction method. Accurate wing twist is actually easy if you follow our instructions (that we hadn't made up yet, when we built these wings, lol ). A bump trim* was added to the right aileron and presto it was in perfect trim. So now I could start grabbing data.

    Conditions; Density Altitude 4700, temp 97 degrees F.
    Winds; SW at 12 knots

    Did a series of stability checks, yaw, pitch and roll all great. Yaw snaps back about as fast as you can pull your foot off the rudder pedals. Pitch is showing positive recovery from push overs and pulls, will dig deeper into this axis later in the program. It does go close to redline before recovery. I see that as not issue, since we will raise the VNE to at least 150 MPH. Roll is the expected stability you get in a high wing. Spiral stability shows very slow to wind up.

    Stalls are very docile. Harry RIblet, you done it again, nice airfoil. There is a nice force gradient as the speed drops. A slight buffet, and break is straight through. This is true with zero to full flaps. The flaps are good for 7 MPH lower stall, and are easy to deploy once at Vfe.

    Airspeed is still not on the numbers, about 10 off at the top and maybe 5 at the bottom. The real proof of a broad speed envelop is the distance, or should I say how little distance is needed for take off and landing. It is very similar to the Raven with the standard wing.

    Vc is coming in right even with standard wing Raven, but we are running into the prop. To easy to red line the engine, with the stock wing, this was not the case. This is a great sign we should get that predicted 5 knots for a Vc of 116 MPH and retain the climb rates.

    Climbs rates are running 800 FPM at 1340 gross with the DA at 4700. This is maintained thru 2000' AGL.

    Overall it is turning out to be a fun flyer, love how it slips up to redline with little coaxing. It is very quiet as well.

    Next up is 1500 GW testing and going for best combo of Vc and b ROC by playing with prop pitch. Eventually I will work up to aerobatics, think we will see a faster roll rate, up to 90 degrees per second, hoping for 100. Our S-10's do 120 plus, about the same as some popular low wings. For most 80 to 90 is plenty fast, but if I can get roll rate with this little pressure, I will take it.
    Stay tuned more to come.

    Today was a busy day of flight testing. Went to 13,500' loaded to 1400 pounds gross. Density altitude was 4400 at take off time. Even that high there was still some climb left, maybe 50 to 75 feet min. A realistic service ceiling for the 1500 gross with the 912ULS would be 12,500. TAS at 13,500' was 90 MPH. TAS at 7,000' was right at 115 MPH.

    Performed lots of stalls all thru the flap range, there is a solid 8 MPH reduction in stall speed with full flaps. It handles 1400 gross very well, good control authority all around at and below stall speeds. Falling leafs are very stable, using less rudder to maintain the level margin.

    STOL performance was tested later in the day at DA's of 5300, it seems to pop off the ground at 50 to 75 feet more roll over the standard Raven wing. This is a guess, we will do some comparison flights using our demo S-7S (it has the same wing as a stock Raven).

    Steep turns show very good energy retention with just over 2 seconds in roll reversals from left to right. Actual roll rate comes in between 70 and 90 degrees per second. I performed barrel rolls, averaging between 4 to 5 seconds.

    Loops are easy with entry at 110 MPH IAS. There is some rudder work at the top to keep wings level, that lessens with higher entry speeds. It accelerates on the down line of the loop a bit faster, but nothing hard to control.

    The off field landing test went very well. This is done at Elizabeth Polly's maker on the hill, a place I have landed most all our STOL planes hundreds of times in all conditions. It was right in the pocket with no pucker factor.

    Tomorrow we plan on some air to air work and comparison flying."

    Mark Pensenstadler
    Site Admin
    S-10 | S-6S | RV-7 | Cherokee 160 | Zenith Cruzer

  2. #2
    Premium Member (Donated)
    Join Date
    Apr 2008
    Merritt Island, Florida


    Thanks for posting Mark!
    Gerry Peterson
    N194GC reserved
    S-19 Relaxed Slow Build.....

  3. #3
    Premium Member (Donated) Tailwindflyer's Avatar
    Join Date
    Sep 2015
    Wichita area KS


    Thanks Mark,

    It all sounds very promising, please keep these flight reports coming.


    S20 build in progress, N71NG reserved

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts