10cc 3D gasser --- An exercise with a VH Sabre-X 51" and a Evolution 10GX

[Enterprise]

Yesterday was the day of CA hinges. After this flight I reglued the aileron back on and flew a few more times. The last flight I put on the Xoar 14x4 and what a difference that made. It flew so much slower and stable it had to be seen to be believed. Right around 10k on the RPM. I forgot to put on the hat cam for this flight (this is the first day with it). With the big prop it seemed much more like a electric airplane with a good stable low speed ability. It still had the pull out and could get enough speed to do high energy stuff. It does knife edge loops pretty violently, and has plently of control throw and power. The CG seems a little too far forward still for easy hovering, but I think flying with a half tank will help with that. By the end of the flight I had realized that the low needle is too high and the motor kept bogging down when at low power for too long which is what led to the dead stick. Retune and repeat next time out.

I am wondering if the motor will spin a wood 15x4. I have all the telemetry hooked up so I can set and alarm for over temping the motor.

After this I had to run to work, but I also realized taking it apart that lower rudder CA hinge is completely ripped and I will need to replace at least this one. Gary told me to use pin hinges on this build, but I wanted to save weight and try to CA hinges as they work perfectly fine on glow planes. I did do pins on my Katana tail and no issues there to this point. I think I will just use a larger CA hinge if I can get in there without having to cut the whole rudder off.

 

[Steve_B]

Looks like it has plenty of power but the extra weight and speed is obviously putting more stress into the airframe.

Based on my glow engine experience a bigger prop should not cause the motor to overheat. It used to be the done thing to run a motor in on a 'too big' prop because it holds the RPM down and gives the engine an easier time. When you go too far you will just loose power.
Totally different to electric....

 

[Enterprise]

I own 8 other gassers, 3 glow, and numerous electrics so I am familiar with the various power systems. The draw to me of this engine is the ability to spin larger prop compared to glow. The plane flew much better on the 14x4 and I hope to get more video in the coming week to demonstrate this point. To the point I was in the video I felt the same way you did in the fact that the weight was forcing more speed than I would have liked.

When I get too big of a prop on a gasser I can feel the lackluster spool up and response. The 14x4 had none of this and since this is just one big experiment I don't mind pushing the size till I get that experience. I am treating this like my 22cc motors way more than a glow or electric. For example I keep wanting a Mej 18x6 to work on my Mintor 22, but everytime I try it, I get the same thrust as the 17x6.5, but crappy throttle response and I can feel how heavy the load is on the motor. 8400 versus 8000, but man what a difference.

 

[Steve_B]

Just checked my previous post and i missed a 'not' out .. i.e. "a bigger prop should not cause the motor to overheat". Kind of changes the context!

Interesting to see how it copes with the bigger prop, I'd guess that it will be like the 18x6 on the Mintor 22 and you wont gain anything, in fact I'd guess that you will get less power due to lower RPM, but I could be wrong!

 

[Enterprise]

I ordered it and the APC 14x4W along with some parts for the upcoming 15cc project which I believe will be more successful as the weights are closer. In that plane I think I will see a excellent flying model that will be a little underpowered at slow speed, but goes a bit faster than the electric version.

Don't get me wrong as I have enjoying flying the Sabre and for the first time I see it as a member of my usual hangar rather than a cool experiement. I does high energy stuff like my little 48" Velox as the mass pushes it through. I need to work on pop tops as I think this will be a great maneuver in this plane. I would be afraid of a full speed blender though.

I just fixed the rudder by putting into two much larger CA hinges. It was probably damaged when the tail wheel broke and it just now fully snapped. With the aft battery, there is just too much weight being put onto those 3 tiny hinges. The aileron bothered me more, but I forgot to drill that little hole to get the CA to fully wick into the hinge. I will have to monitor both of them. The elevator is solid despite the servo coming out. To date I have yet to find any fatigue in the airframe itself. More flying on Wednesday I hope.

 

[gyro]

Awesome flight reports and video today, really enjoying watching and reading about your experiments as this project comes to fruition!

-Gary

 

[njswede]

Stumbled across this one on youtube today of Cody flying the gasser Sabre X. Looks pretty nice to me!

[video=youtube;611llzx2Lx4]http://www.youtube.com/watch?v=611llzx2Lx4&feature=youtu.be[/video]

Then again, Cody can probably do rolling harriers with a brick...

 

[Enterprise]

I think that was the flight with the APC 14x4. Later on we tried a Xoar 13x4 wood that was a lot better, but the "arrival" broke the prop. Got a new one and the weather has conspired since then. I tried to get both flights with hat cam, but the footage is pretty bad.

Cody tuned the engine later and it turns out the low was stupid rich and not it runs a lot better at low throttle. I was hoping to get more flying in before doing another update and I forgot that this gentleman video'd the first flight.

The airplane clearly is capable of 3D flight and has adequate power. Just trying still to find a good prop combination and find time and weather to get more than a few flights in. I am already compiling a list of things to change if I do a V2.

Cody did not like the servos. I personally can not tell at this point, but if I flew a 7245 setup right next to it then maybe. More updates forthcoming as the weather might actually be spring soon.

 

[cwojcik]

Actually, if you fast forward to about 8:15 in that video, you can catch a bit of the second flight with the 13x4. That prop made a huge difference on the engine. It was very clearly overpropped on the 14x4W APC. With the 13x4, response was great, power was adequate, and tuning was easy. It seemed like the perfect load to me...would have to try it with the 14x4 to be sure. Too bad I broke it in a "landing."

The plane flies very well. It really feels just like a glow plane. Not a huge amount of power, but certainly enough for basic 3D, and due to the way that the torque curve works on a gas/glow motor (this motor behaves a lot more like a glow motor than a larger gas motor), you can still get plenty of speed for tumbles, even with a 4 pitch prop.

The airframe itself flies pretty well. I think that a 3DHS or EF airframe would be more precise and easier to 3D but it has a nice, no-rock harrier. The side area distribution isn't perfect for KE and it has a fair bit of coupling, but as a budget airplane for beating around or mad science it's a good option. I think that a 3DHS 57" Extra would also be a good choice for this motor because it's very light and does very well on a wide range of power options.

The servos suck. They are extremely slow, don't center, and have poor resolution. I didn't notice any blowback though. We have looked high and low for good alternatives to 225MG's and there really aren't any for less money...though for extreme flying there are a few really good options out there for more money.

I think at this size electric still wins by a long shot for 3D. Sure you get long flight times, but the batteries in this size plane are small, cheap, and can be charged quickly. Still, there are some big advantages...if you wanted something with super-long flight times for AP, FPV, or just putting around this would be great. This motor in a Cub or something would be perfect (actually, if I ever get time maybe I'll dust off my old cub and get one these...). But, it is viable.

I really look forward to seeing how the 15cc motor does in a 60" plane. As you move up in size, the weight advantage of electric starts to rapidly diminish. I looked at putting a DLE 20 in my Osiris vs. the 5S 5000 setup it has now and the weight was pretty much the same.

 

[gyro]

Actually, if you fast forward to about 8:15 in that video, you can catch a bit of the second flight with the 13x4. That prop made a huge difference on the engine. It was very clearly overpropped on the 14x4W APC. With the 13x4, response was great, power was adequate, and tuning was easy. It seemed like the perfect load to me...would have to try it with the 14x4 to be sure. Too bad I broke it in a "landing."

The plane flies very well. It really feels just like a glow plane. Not a huge amount of power, but certainly enough for basic 3D, and due to the way that the torque curve works on a gas/glow motor (this motor behaves a lot more like a glow motor than a larger gas motor), you can still get plenty of speed for tumbles, even with a 4 pitch prop.

The airframe itself flies pretty well. I think that a 3DHS or EF airframe would be more precise and easier to 3D but it has a nice, no-rock harrier. The side area distribution isn't perfect for KE and it has a fair bit of coupling, but as a budget airplane for beating around or mad science it's a good option. I think that a 3DHS 57" Extra would also be a good choice for this motor because it's very light and does very well on a wide range of power options.

The servos suck. They are extremely slow, don't center, and have poor resolution. I didn't notice any blowback though. We have looked high and low for good alternatives to 225MG's and there really aren't any for less money...though for extreme flying there are a few really good options out there for more money.

I think at this size electric still wins by a long shot for 3D. Sure you get long flight times, but the batteries in this size plane are small, cheap, and can be charged quickly. Still, there are some big advantages...if you wanted something with super-long flight times for AP, FPV, or just putting around this would be great. This motor in a Cub or something would be perfect (actually, if I ever get time maybe I'll dust off my old cub and get one these...). But, it is viable.

I really look forward to seeing how the 15cc motor does in a 60" plane. As you move up in size, the weight advantage of electric starts to rapidly diminish. I looked at putting a DLE 20 in my Osiris vs. the 5S 5000 setup it has now and the weight was pretty much the same.

I agree Cody, I'd also really like to see a 15cc in a 60" class. If anyone wants to send me at 15cc motor and airframe, I'll build it! I think that the 7245MH servos would be nice on that side airplane... I've got them in my MXS and they're awesome. I also like the 3dhs line for this project, since they already are balanced with the servo in the rudder tray, shifting a little extra weight rear by moving the servo back is super easy. I'm really intrigued by the feasibility and performance. As a consumer, I'd be ok paying a little more for the longer flight times if the performance was close to equal.

-G