Cessna AG-Wagon By Larry Kruse scratch built ??

[frank mccune]

      Hi All:

      Is there anybody out there who has flown one of these profile airplanes?  I have one that is built ready to have an engine installed and have elected to use a HP .40 Gold Head for power.

     The plans call for a .35 engine so my OS .35S and OS .30S engines come to mind.  Will a .35-.30 engine have enough power to fly this plane well or should I opt for the more powerful HP .40?

    Comments?

                                                                                                                                                 Tia,

                                                                                                                                                 Frank McCune

[Dan McEntee]

     The airplane is essentially a Twister, so , yes your engine should do just fine. I built one this summer and massaged the outlines to look like the real Air Tractor crop duster that was painted up like Dusty from the movie "Planes." There are pictures of ithere on the forum somewhere, probably in coverage of the Paducah,KY contest. I got a 517 score with it in Profile on it's 7th or 8th flight. Mine is powered by a stock LA.40, I added a rib bay to each wing to make it resemble the crop duster wing more, and increased the stab area a bit when I reshaped it to look like the Air Tractor. The tail was lengthened just a bit over the plan tail moment which was the same as a stock SIG Twister. I made up a small box that holds a mini servo, receiver and small 2 cell Lipo battery to operate a throttle. For scale contests, I put the box and carb on and control throttle with a Spektrum DX-i6 transmitter. When flying stunt, I pull that off and put on a venturi and needle valve assembly. Worked out well so far. Like I mentioned, got a 517 for profile stunt at Paducah, and at out scale contest here in September I finished second just 6 pints behind a real nice American Hustler that has flaps and retracts. This all may be more than you wanted to know, but hey, I was on a roll! Of what you have listed for available engines, try the OS.35S, since all that you will probably be flying is stunt.
   HAPPY HOLIDAYS!
   Dan McEntee

[frank mccune]

     Hi Dan:

     Thanks for the reply!

     I have a nib OS .35S and a HP .40 Gold Head that is also nib.  I also have an OS .30S and a HP Gold Head that are like new.  I am now flying a Twister that is powered by a HP Gold Head .40 that is a dream to fly.  It is a bit faster than I deem perfect, but it flies very well at the higher speed. Perhaps it is overkill in power but these old HP engines are a great engines!  I also fly an Midwest Me 109 that is powered by an OS .35S and it too flies very well despite the fact that it is much slower than the Twister. 

     I am attempting to determine how much power one needs for powering a Stunt/Sport airplane that is 400-500 square inches in wing area. It seems that in our club, people are going to engines like the OS LA .40 and .46 for power.  Even the Noblers are powered by these engines plus a Stalker .40 thrown in for good measure.  How fast do these planes have to fly to keep good line tension? The proponents of more power seem to enjoy the additional speed and line tension through the maneuvers.  Me, I like to go as slow as possible but maintain good line tension at all times.

                                                                                                                                  Have a great Holiday season,

                                                                                                                                  Frank McCune

       

[Dan McEntee]

  Hi Frank;
    Line tension can be affected by just changing a prop. As for speed, I like to fly between 5 and 5.4 seconds per lap. A lot depends on the airplane. Some models seem fast at 5.2 and others look like they are just loping along. That is what test flying is all about, getting things consistent and figuring out just what you personally prefer. For models in the 400 to 500 square inch range, anything from a LA/FP.25 to the LA.46 will do the job with the proper prop and line length. If you get an airplane/engine combination that is working well but still a bit fast, go to 2 foot longer lines and try again. You will see a difference. The airplane actual ground speed will be the same but lap times will be slower. On a new model, I try to be a bit long on line length, so if I need to, it's easier to re-wrap one end of the lines to shorten them. They haven't invented a line stretcher as of yet! Go with the engine you want and just be purposeful in your final trimming stages and you'll be happy. A lot has been said on the forums about the LA/FP.25 and the power they make. I have flown them both on these types of models and they will perform but the model had better be on the light side. I had a Fancherized Twister with an LA.25 on it and it would do the pattern just fine in calm winds, but when it started to blow a bit, things would get on a ragged edge, no reserve power. If pressed to put a weight limit on them, I would say 30 to 35 ounces. Anything heavier towards the 40 ounce range and you have to fly in wind of any kind, go with the larger displacement.
  Good luck and have fun,
  Dan McEntee

[Fred Cronenwett]

This is the Dusty model that Dan flies, these are pictures taken during our annual Broken arrow CL stunt/scale contest here in the St Louis area in Sept

Fred

https://lafayetteesquadrillecl.wordpress.com/lafayette-esquadrille-cl/photographs/photographs-2015/broken-arrow-buder-park-control-line-photos-2015/

[Fred Cronenwett]

one more picture

[Fred Cronenwett]

Engine running

[Fred Cronenwett]

Ok, I still have more pictures...

[Fred Cronenwett]

This is the throttle box that Dan was talking about

[Dan McEntee]

   Thanks a lot for the photo help Fred!!You may notice from the photos that there is some dihedral in the wing. Since this model was going to be used for profile scale competition also, I wanted it to match a front view of the real airplane as much as possible. I just did a "looks about right" engineered guess and dropped the wing 3/4" and added 3/4" under each wing tip to get the vertical CG back where is was, at least approximately. The only trim adjustment made so far is some tail weight. I'll probably add a bit more juist to help out with slow speed elevator authority so I can make three point landings a bit better.
   Now that I have done the "real" version, I have a cartoon version in mind just for stunt. I need to clear  off the drafting table to draw up the fuselage for that one, but hope to have it available next spring or summer. It will look more like the movie character, and Ihave heard that the movie character was a composite of several; different brands of crop dusters.
   Type at you later,
    Dan McEntee