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  • Hollmann HA-2M Sportster

    Construction has begun on my Hollmann HA-2M Sportster, I have ordered my first batch of aluminum from Aircraft Spruce and Specialty Company. I predict about 1498.5 hours build time remains.
    Cortland Carrington USAF 86-06 and then again in 09.
    Bloomington, Indiana
    Retired C-130 Loadmaster 1200 hours
    Private Pilot FW 110 hours
    Gyrocopter student 1 hour
    PRA Member 42043
    Gyrocopter builder, 475 hours
    Cort's Hollmann HA-2M build
    http://www.rotaryforum.com/forum/showthread.php?t=25539
    "Best to open thy mouth and look like a fool, than violently auger deep into the earth"

  • #2
    Keep all of us posted with regular updates and photos of your build.

    Thanks,

    Wayne

    Comment


    • #3
      Stats thus far:

      About 6 hours invested into reading and understanding the prints.

      $536 for the design prints and operating manual.

      $140, in 6061T6 2x2’s, 0.125 plate stock (4sqft), and AN hardware. This material will construct the inner core of the aircraft comprising the main keel, rotor mast, center cabin diagonal keel, and the gusset plates required for these members.

      Now I can say I’m about 90% complete; however, that last 10% seems like it takes forever!

      Anyway, as designed this machine is HTL… I know, I know, I know. I do want to say this design does have a good amount of both vertical and horizontal stabilizer immersion in the prop’s wash, so that is a significant positive attribute to offset the HTL tendency of this particular HLT design.

      I think it’s logical to say that in an HLT design when you are in straight and level flight, and add power the nose would otherwise tend to lower (not desirable or an unstable trait). However in this HLT design because the horizontal stabilizer is right behind the prop the increased air velocity from the additional power would generate greater additional negative lift to counter balance the tendency of the nose to drop.

      Has anyone ever built a Gyro that has a progressive trim tab on the immersed horizontal stabilizer that is coupled to the throttle in an HLT design? So, that when you apply power the elevator rotates slightly to increase negative pitch to the H stab which keeps the nose level or even raises it slightly? Also as power is reduced in an HLT design the nose tends to raise (undesirable) in the above described throttle linked to the horizontal trim tab, more positive lift would be generated when power is retarded to cause the nose to drop slightly. Is this a common way to reduce the natural instability of an HLT design? I think it probably is, but I’m not an aircraft designer.

      In regard to PIO and PPO of this design, it is aerodynamically “neutral” based on the dimensions of the design as built to plan specifications during computer modeling. PIO in this design does not amplify if a disturbance of one of the other forces of flight on the airframe changes (thrust, drag, lift or weight) There is no amplification of the disturbance that increases the pendulum swing effect when left in a “hands off the controls satiation.” In other words if oscillation is induced in this design either by the pilot or natural factors, it remains constant, but does not amplify/increase or diminish/reduce. This is neither good or bad, it’s indifferent.

      As to my understanding of stability, you desire an aircraft that will raise the nose on acceleration and lower the nose on deceleration. The great question/debate is how do you make that occur…
      Cortland Carrington USAF 86-06 and then again in 09.
      Bloomington, Indiana
      Retired C-130 Loadmaster 1200 hours
      Private Pilot FW 110 hours
      Gyrocopter student 1 hour
      PRA Member 42043
      Gyrocopter builder, 475 hours
      Cort's Hollmann HA-2M build
      http://www.rotaryforum.com/forum/showthread.php?t=25539
      "Best to open thy mouth and look like a fool, than violently auger deep into the earth"

      Comment


      • #4
        I was under the impression that this is already a neutrally stable aircraft by design and the test sheet is avaiable on Hollmans website as a free down load but here is the direct link.

        http://www.aircraftdesigns.com/gyropitch-outputs.html

        Are you going to build this with his original cabin design or more like the cabin on the RAF or Sparrowhawk

        Dan
        Dan McGee
        PRA # 41699
        Support the PRA, Join today!!
        If you can't have fun doing it, it's not worth doing.
        Be a pig not a hog, hogs get slaughtered, Pigs get fed.

        Comment


        • #5
          opps I just read the bottom of your post and said the same thing I was thinking so disregard.

          But will still be interesting to see how you build this aircraft. If it performs well for you then I will spend the money and add the plans to my library
          Dan McGee
          PRA # 41699
          Support the PRA, Join today!!
          If you can't have fun doing it, it's not worth doing.
          Be a pig not a hog, hogs get slaughtered, Pigs get fed.

          Comment


          • #6
            Hi Dan, I was planning to keep it as much as possible to the original design, but I may not use fiberglass in the areas it calls for fiberglass. I’m not yet sure how I want to approach that yet, I’m leaning to carbon fiber or I could use aluminum. I could even use fabric and dope in a few places. I can say that I’d like to bump the fuel tank size from 12 to 15 gallons, and thinking I’ll go with the EJ Subaru 2.2 EFI which drinks 6.0GPH at 75% power. That should get me a full 1.6 hour flight time at 80MPH, and the aircraft can handle the extra 3 gallons for the weight, and it falls within the CG range as well. This also would give me my 30 minutes reserve fuel level. I don’t like the design of the current fuel tank; it holds 1.5 gallons unusable, which is a lot for only a 12 gallon tank.
            Cortland Carrington USAF 86-06 and then again in 09.
            Bloomington, Indiana
            Retired C-130 Loadmaster 1200 hours
            Private Pilot FW 110 hours
            Gyrocopter student 1 hour
            PRA Member 42043
            Gyrocopter builder, 475 hours
            Cort's Hollmann HA-2M build
            http://www.rotaryforum.com/forum/showthread.php?t=25539
            "Best to open thy mouth and look like a fool, than violently auger deep into the earth"

            Comment


            • #7
              You may need more fuel.

              Hello Cortland,

              In my opinion you will need to get down to 80 horse power to only burn 6 gallons of gas per hour.

              With the added weight of the Subaru and the extra weight of the fuel I suspect you will use more than 6 gallons per hour to fly.

              Perhaps some of the people here flying a 2.2 Subaru in a gyroplane would share their consumption numbers.

              I like to plan my trips to land with a about 7 gallons. I have found it doesn’t take much headwind to burn a lot of extra fuel when you fly slow. I have 22 usable gallons on board.

              Thank you, Vance
              Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

              Comment


              • #8
                Thanks Vance, I got the 6.0GPH from a supplier of aircraft prepped 2.2 subies and they advertise that at 75% power, they consume 6.0GPH with the EFI, Also the rotax 912 (carbed) (80HP) that i fly burns 4.0 GPH at 75% power, as an observation, at full slant she drinks about 5.2GPH.. ON the subie I bet I'll be about 7.0GPH, so you can see why I want 15 Gallons gas on board... cause I actually want to fly places more then 25NM miles away from home...

                Anyway,

                In the design of the Hollmann HA-2M (Hamster) because the cabin enclosure makes it look like a hamster with food packed into its cheeks… Anyway, the fuel tank centroid is essentially an aluminum box that is located 23 inches forward of the center of the operational range of the aircraft’s center of gravity. The tank is 12 gallons with only 10.5 usable. I intend on making a few tweaks of the tank bottom to increase the usable fuel level, and to increase the fuel level to 15 gallons. I have the room in around the tank to do so.

                23 inches centroid to centroid seems pretty far forward of Aircraft CG for a fuel tank? What say you…

                Because the tank is so far forward of aircraft CG I was not able to simply make a larger tank at the same location, because it puts my max weight takeoff CG forward of the operational CG limit by about 1 inch. Bummer!

                I did my calculations last night on the original design and discovered that I can leave the tank exactly where it is in its same foot print, but instead of it being simply rectangle with a constant centroid at 23 inches fwd of CG, I can transform it into the shape of a parallelogram sloping in the direction of the rotor mast. By doing that, the tank now has a moving center of gravity. Full fuel moves the tank’s CG back toward the rotor mast by approximately 6 inches, ½ tank by 3 inches aft, and at ZF I’m right back to where I started. I verified that under all fuel and passenger loading configurations where the aircraft meets minimum and maximum operational weights, my aircraft CG falls with in design limits. And I am not over gross weight by increasing full fuel load from 12 to 15 gallons.

                Actually it’s not a parallelogram, as the back side slopes more then the front does, so the sides are not parallel; therefore, it is not a parallelogram! That is how I got the increase from 12 to 15 gallons, the fact that it is not a parallelogram. I added this paragraph in as an after thought, because I figured someone here would catch this fact and taunt me :)

                So how far forward or aft of aircraft CG range is your fuel tank?

                Also with the additional fuel, I’m at 1070 pounds max gross flight weight assuming that my engine comes in at under 233 pounds.
                Attached Files
                Last edited by ironcowboy; 04-13-2010, 05:35 AM.
                Cortland Carrington USAF 86-06 and then again in 09.
                Bloomington, Indiana
                Retired C-130 Loadmaster 1200 hours
                Private Pilot FW 110 hours
                Gyrocopter student 1 hour
                PRA Member 42043
                Gyrocopter builder, 475 hours
                Cort's Hollmann HA-2M build
                http://www.rotaryforum.com/forum/showthread.php?t=25539
                "Best to open thy mouth and look like a fool, than violently auger deep into the earth"

                Comment


                • #9
                  Vance is right about the fuel consumption - a 4 stroke will burn around 6 gallons per hour @ 80 hp, no way around that.

                  So it's really about a 110 hp engine at max power as it's configured, or they're fudging either the fuel consumption or power setting they're calling "75%".
                  Brett Sumpter
                  Roswell, GA

                  Comment


                  • #10
                    ha 2 m sportster

                    the glanville skymaster which was a virsion of the sportster had the fuel tank on the firewall behind the seats and was the full width of the cabin, it worked better than the sportster set up.

                    Comment


                    • #11
                      I don't have an opinion.

                      Originally posted by ironcowboy View Post

                      So how far forward or aft of aircraft CG range is your fuel tank?

                      Also with the additional fuel, I’m at 1070 pounds max gross flight weight assuming that my engine comes in at under 233 pounds.

                      Hello Cortland,

                      My two 11 gallon tanks centers are a few inches ahead and below CG.

                      I don’t have weight and balance with me in Florida or I could tell you exactly.

                      I have included a picture so you can get an idea.

                      They are slightly below the center of gravity and as they empty she flies noticeably different.

                      The passenger’s center of gravity is several inches ahead of the CG of the aircraft and she flies a little differently solo than she does with a 250 pound passenger.

                      She hangs noticeably more nose down with a 160 pound passenger.

                      The Predator’s gross weight is 1,400 pounds with 30 foot blades and 160 horsepower.

                      The horizontal stabilizer is close to zero angle of attack in level flight at 60kts.

                      I would call Martin for an opinion on how sensitive the Sporster is to center of gravity and weight changes. He has flown with a wide variety of pasanger weights.

                      He has spent a lot of time explaining his opinions to me and I am not building a Sporster. In my experience he is very generous with his knowledge.

                      Thank you, Vance
                      Attached Files
                      Regards, Vance Breese Gyroplane CFI http://www.breeseaircraft.com/

                      Comment


                      • #12
                        Hi Cortland,

                        Interesting ideas you have.

                        IMHO, I'd stick with using the Lycoming O-320. The simplicity is in the installation. With the Subaru, lots of modification, set up, tinkering, and the like which add complexity. There are numerous used O-320s out there at reasonable prices, ready install and operate.

                        Still, I'm enjoying reading about your ideas and progression.

                        Thanks,

                        Wayne

                        Comment


                        • #13
                          First Cuts this afternoon

                          Okikuma,

                          I think your right, I think I’ll go with a O-320, simple… and I can have it fuel injected for a price.

                          I made my first cuts tonight. The 81deg rake of the double 2x2 rotor mast, the center cabin keel, and the main cabin lower keel, these three members comprise the main inner core of the whole aircraft and everything else will be added to these three tubes. The diagonal 2x2 runs through the center of the cabin and separates the pilot and passenger.
                          Attached Files
                          Last edited by ironcowboy; 04-14-2010, 08:45 PM.
                          Cortland Carrington USAF 86-06 and then again in 09.
                          Bloomington, Indiana
                          Retired C-130 Loadmaster 1200 hours
                          Private Pilot FW 110 hours
                          Gyrocopter student 1 hour
                          PRA Member 42043
                          Gyrocopter builder, 475 hours
                          Cort's Hollmann HA-2M build
                          http://www.rotaryforum.com/forum/showthread.php?t=25539
                          "Best to open thy mouth and look like a fool, than violently auger deep into the earth"

                          Comment


                          • #14
                            The hollman machine dont like long cabins . I lost a friend 2 weeks ago , he change the original cabin to a Scorpio type. It was nose heavy , plus other things.

                            I would put a round tube inside the 2x2 in the mast to stiffit more also to help in a roll event .
                            CHarles

                            Comment


                            • #15
                              the mast looks like it 2 each 2x2s why add more
                              Brent Brown
                              brentbrown@caci.com
                              ezgb@earthlink.net

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