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Doghouse Extreme Model Airplane Review, with OS .91 Surpass II
By Evan Chapkis
See the Doghouse extreme web site here.
Got up early this morning and finished installing the throttle servo and linkage. After breakfast, I installed the tank and plumbing, attached the prop, installed the receiver, and 1600 Duralite battery. An 800 will be raplacing the 1600 soon. Another 1.5 oz savings.
I checked the cg, and was a tad tail heavy, but this was by design. I put the battery, receiver, and throttle servo in the very rear of the radio compartment. The setup was about 1/4" past the cg location on the plans. I figured it was easier to move the battery forward than to add dead weight. The overall weight is 5.7 lbs.
The engine is an OS 91 Surpass II. I didn't have a spinner or safety nut, I decided to get one at the hobby shop on the way to the field. On the way to the field, I forgot about the hobby shop and went and flew.
The plane was tail heavy, but nothing to be concerned with. I set my throws on low rates, about 20 degrees aileron and elevator, and left the rudder at high rate, about 50 degrees.
The plane took off in about 10 feet at about 3/8 throttle. Minor elevator and aileron trim was needed. Roll rate was incredibly fast at 20 degrees throw. Landed after a few passes and reduced the aileron by 5%.
I put in 5-6 flights, each making small adjustments. I ended up adding right and down thrust, adjusting the ailerons down a tad, adding 1.5 oz of weight up from with the tank, lowering rudder throw, expo adjustments, adding rudder to aileron mix (about 7%),and no rudder to elevator mix is needed.
Even on low rates, the plane is very easy to hover. Reduce your throttle by 1 click and the plane will start to torque roll and descend. With low rates you can still control the plane. I didn't get the chance to go to high rates.
This has to be the easiest plane (even better than a Sig Kadet) to land. Typical landing is tail wheel first. No tip stall issues at all.
I am using an APC 14x6 prop and with that big of a prop, braking is the best I have ever seen. You can easily fly the landing in a very nose high attitude and touch right down.
All the control surfaces are very effective. It doesn't take much to roll, loop, or hammer the Doghouse.
The 14x6 does not give the plane an unlimited vertical. I was surprised, but the engine is running rich. It really lowers the engine output but not the torque. A 13x8 would be ballistic.
One of the impressions I get while flying it is that your flying the engine. The 91 is so large compared to the plane that you can distinctly see the engine while the plane is flying. A 45 will fly this plane nice as well.
I still have more trimming to do, but it is a winner. For those of you that have started the kit yet, do not use the dihedral brace, make the wing flat. I also moved the firewall back 1" per Chip Hyde. I can't tell you if it flies any different, but it does make the plane balance.