rhodenga500
One of my flying club members that have a large gas prop plane mentioned to me that he have adjusted his flaps slightly downward (very little) and adjust his elevator slightly upward (very little) to compensate for the slightly downward flaps. This gives his plane a little more stability. It did not seem to slow his plane down, nor improve his speed.

I noticed that these large straight winged gas prop planes have only a little aileron movement but ailerons are longer in length.

Will this improve the stability of a parkjet when using elevators only, (with aileron - elevom mixed) and slightly downward (very little) flap position?
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Sterling101
Normally the reason to add some flap is to add drag to the main wing, so adding a touch in normal flight will just add a little drag. If you add a little up elevator you will add a little more drag so it would effectively slow things down a bit. But, with the drag in place it will make it a little more docile in the air.

The trade off with aileron length is the shorter they are, the more deflection they are likely to need. You tend to see a lot of large ailerons on the gas/glow engine planes as they normally tend to be bigger builds in general so they need a little more deflection but it's easier to have a larger control surface as you have the room.

I'm not sure adding flap deflection to a parkjet would work too well though due to the scale that we normally work at. I think it would just unsettle the airflow and make it a bit of a hand full to fly...
Whoever said nothing is impossible had obviously never tried slamming a revolving door...
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e3_Scott
Quote:
One of my flying club members that have a large gas prop plane mentioned to me that he have adjusted his flaps slightly downward (very little) and adjust his elevator slightly upward (very little) to compensate for the slightly downward flaps. This gives his plane a little more stability. It did not seem to slow his plane down, nor improve his speed.

I noticed that these large straight winged gas prop planes have only a little aileron movement but ailerons are longer in length.

Will this improve the stability of a parkjet when using elevators only, (with aileron - elevom mixed) and slightly downward (very little) flap position?


Hi Rhodenga -

I fully agree with Sterling about a flaps/elevator mix being a challenge to stability for just general flying around in a flat wing park jet. Certainly they have their applications for extreme slow flight/high alpha or to shorten landing approach and/or soften landing, but just for general flying around, I would agree they could cause more problems than they would solve.

What I have noted with foam park jets and watching other fellows fly more conventional foam airplanes at my field is that drag can be a much bigger enemy to foam planes than larger, heavier balsa planes as the foam planes bleed off energy and lose momentum much faster. I have found that playing with flaps in park jets has required a serious amount of fine tuning to ensure the flaps are deflected at the right rate/speed and there is no imbalance in deflection otherwise the plane can slow down too fast and/or start pulling one way or the other. When this happens when the plane is already slow or slowing down quickly, it can make recovery very difficult. It can be done, but for just general flying around, it could lead to more instability than stability. I would certainly do all my testing up high to see what your plane does when you flip your switch for flaps to give you time and altitude to recover it if does something weird.

There are certainly multiple factors and lots of little things that can be done to improve the stability of a park jet. In all the testing and experimenting I have done with park jets, the single greatest improvement has shown to be battery position in relation to the wing plate. Normally, the battery is the single heaviest component in our park jets, so it's location is critical to helping stability. Planes that have the battery positioned to be either neutrally balanced vertically or in fact "bottom heavy" (battery low in relation to the wing plate) have typically been the most stable planes I have flown.

The F-18 V3 "smart plane" is a prime example of this. RC Powers designed it with the battery sitting quite low in relation to the wing plate, building in a "smart" or self righting tendency.

In my experience, planes with the battery up high can be more aerobatic, but certainly less stable as they will want to flip on their backs when slow in turns or other maneuvers.

When I am selecting a plane to build or tinker with, one of the first things I like to look at is where the battery will be located in relation to the wing plate or if it is possible to lower it without much difficulty if I want to have a good stable platform to fly.

Hope this helps, good luck

Cheers,

Scott
Park Jet noise...the "other" sound of freedom😎
#ParkJetnoise #ParkJetpilot
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DualDesertEagle
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Planes that have the battery positioned to be either neutrally balanced vertically or in fact "bottom heavy" (battery low in relation to the wing plate) have typically been the most stable planes I have flown.


This coincides with top wing aircraft being more stable than middle or bottom wing ones due to their wings being the highest point beside the rudder.

Which just made me realize that my Dominator ain't gonna be so stable due to the wing being the very bottom of the plane.

Learning from this forum every day...
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rhodenga500
Thanks for the replies,

All the info is very helpful.

I am a sucker for experimentation.

My next question:

In some of my parkjets I have a NX3 EVO flight stabilizer (with auto leveling) that works good. When installed, I only connect ailerons for auto leveling to the stabilizer. The stabilizer only requires minimum gain set (probably less than 25%) for my parkjets, so there is very little movement needed to stabilize the plane (motion barely noticeable).

I was fooling around with one of my flight stabilizers and notice that when connected to a power source and servo it works (auto leveling) without any input signal from the receiver. So, another thought came to my mind as follows:

I have just finished repairing my prototype, dual rear motor mounted props on my Mig-35 with elevators only (aileron - elevon mixed). If I activate my ailerons and connect the flight stabilizer (with minimum gain/throws as needed) to ailerons only with no input from the receiver; connect my power source and connect on/off switch wire to the receiver to activate the stabilizer in windy conditions. Remember, when the stabilizer is off, the stabilizer will hold the ailerons in the neutral position. Will this work?

If the answer is yes, I know when the stabilizer is left in the "on" position in normal flight, this will cause some negative effects when turning right or left and inverted flight, but the negative effects and drag should be minimum due to the minimum throws of the flight stabilizer. Probably will not cause a crash.
My main controls will be elevons only. The stabilizer on/off switch wire (only) will be connect to the receiver and another wire from by BEC to the flight stabilizer as a power source. The ailerons will be used only for flight stabilization with minimum throws. Of course, the elevators throws will be increased a little to compensate for the negative effects of the flight stabilizer.

If the answer is no, you all have save me a lot time and trouble in experimentation.
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e3_Scott
Quote:
Thanks for the replies,

All the info is very helpful.

I am a sucker for experimentation.

My next question:

In some of my parkjets I have a NX3 EVO flight stabilizer (with auto leveling) that works good. When installed, I only connect ailerons for auto leveling to the stabilizer. The stabilizer only requires minimum gain set (probably less than 25%) for my parkjets, so there is very little movement needed to stabilize the plane (motion barely noticeable).

I was fooling around with one of my flight stabilizers and notice that when connected to a power source and servo it works (auto leveling) without any input signal from the receiver. So, another thought came to my mind as follows:

I have just finished repairing my prototype, dual rear motor mounted props on my Mig-35 with elevators only (aileron - elevon mixed). If I activate my ailerons and connect the flight stabilizer (with minimum gain/throws as needed) to ailerons only with no input from the receiver; connect my power source and connect on/off switch wire to the receiver to activate the stabilizer in windy conditions. Remember, when the stabilizer is off, the stabilizer will hold the ailerons in the neutral position. Will this work?

If the answer is yes, I know when the stabilizer is left in the "on" position in normal flight, this will cause some negative effects when turning right or left and inverted flight, but the negative effects and drag should be minimum due to the minimum throws of the flight stabilizer. Probably will not cause a crash.
My main controls will be elevons only. The stabilizer on/off switch wire (only) will be connect to the receiver and another wire from by BEC to the flight stabilizer as a power source. The ailerons will be used only for flight stabilization with minimum throws. Of course, the elevators throws will be increased a little to compensate for the negative effects of the flight stabilizer.

If the answer is no, you all have save me a lot time and trouble in experimentation.


Hi rhodenga -

Sorry, I can be of no help to you WRT stabilizers and their setup. However, there was a discussion recently on the Parkflyer's International F/A-18 G1R thread starting on this page https://rcpowers.com/community/threads/parkflyers-international-f-a-18-super-hornet-g1r-a-new-experience-a-new-frontier.22167/page-10 starting at post #198 where Bimo posted video testing some modes on his stabilizer mounted in his F/A-18.

Is the Mig-35 a design of your own?

Good luck with the experimentation

Cheers,

Scott
Park Jet noise...the "other" sound of freedom😎
#ParkJetnoise #ParkJetpilot
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whatmovesyou
Have done 2 different projects like you are suggesting.

Question 1: If the plane is tilted(roll) with the FS on, that means that the ailerons will be deflected to counteract the roll. Now you shut off the FS by the power in switch, does the ailerons stay put in deflected mode? . If so, won't go.

Question 2: If you shut power off and on, what submode does the gyro revert to when turned on? headlocking or gyro

Worst case, you will need to go at least 3 crash heights to play with this idea. Having aileron deflection(even partial) going against rear elevons might cause some funky flying. Did elevon canards and elevons on a park jet, it was super sensitive.

Sharing 1/2 projects,I wanted to duplicate the CL-84 wing fixed at 30 degrees up on my transport. Used the gyro to control pitch (elevator) so at all times the fuse is parallel to ground. Could shut it off in flight if needed. My large wing had elevons on it and I had thrust vectoring for yaw so I could fly the plane by the seat of my pants approach.

Ended up being a cool project where throttle management controlled height and yaw, using the ailerons with TV, like a trainer, did your turning in flight.

In response to the initial flap/elevator question, he needs to move the CG forward for better stability, not using the flap/elevator. Ask that pilot to demonstrate what happens in a vertical climb/stall turn/vertical descent with the flaps/elevator adjusted?
I like to design and fly unique planes.
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