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Add pusher power Pod to Simple Soarer

#1
I am about to build a SS as project to entertain me as I recover from should replacement surgery.

I plan on using it as both a tow launch and power glider.

That said, I am toying with the idea of adding a power pod above and just aft of the wings. Something similar to the Bixler (II).

So, any ideas or suggestions on how to go about doing this?
 
#2
Pushers are tricky for a number of reasons. First off, you are going to need to find a way to mount the motor above the wing. *way* above the wing in the case of the Simple Soarer. This can be a bit tricky without adding a lot of extra weight.

Because you are removing weight from the nose and adding it behind the CG, you are going to need to add a *lot* more weight in the nose and/or stretch the nose a fair bit.

Adding weight means you either need to fly much faster or use a wing with more lift.

And finally, you need to be aware that you are going to have thrust line issues. You are going to need to have a fair amount of down-thrust to keep the plane level when you accelerate.

If you want to build a pusher, my suggestion is to start with something like the Experimental Airlines Axon or the Smash Drone.
 
#3
Excellent points. Thanks!

I guess I should get it built and flying before making a major mod like that. I'm not giving up on the idea, but I definitely will give it a LOT more consideration before jumping in.
 
#5
pgerts: Do you have any idea why the prop-behind-wing setup has gotten so popular in recent years while prop-over-wing seems rather uncommon? Prop-over-wing seems to make a lot more sense putting the additional weight of the motor directly over the CG. All I can guess is that with the shift from gas to electric you have the option of using the battery to balance out the weight of the motor.

I also wonder about thrust angle issues. Ideally, the thrust line of the prop should pass through the center of drag, which is pretty much impossible when the center of drag is directly under the prop. Were the motors on these planes less about powered flight than as a means to get the plane up to altitude for thermal soaring?
 

Tritium

Amateur Extra Class K5TWM
#6
Prop behind wing has gotten popular because it protects the prop in nearly all crashes. ;)
It also removes the prop from the camera view when doing Aerial Photography or FPV.

Thurmond
 
#7
pgerts: Do you have any idea why the prop-behind-wing setup has gotten so popular in recent years while prop-over-wing seems rather uncommon? Prop-over-wing seems to make a lot more sense putting the additional weight of the motor directly over the CG. All I can guess is that with the shift from gas to electric you have the option of using the battery to balance out the weight of the motor.

I also wonder about thrust angle issues. Ideally, the thrust line of the prop should pass through the center of drag, which is pretty much impossible when the center of drag is directly under the prop. Were the motors on these planes less about powered flight than as a means to get the plane up to altitude for thermal soaring?
I can't speak to the models pgerts mentions from the 60-80s as i was nothing more than a glimmer in my mothers eye but will say I have seen several very low powered top wing applications for scratchbuilt glider designs that are simply there to aid in maintaining altitude when cruising from thermal to thermal. Really don't have the "climb out" umph seen in ARF Radian type models. Some have even got tricky with a switchable up or down pod position so that the motor and pod can be tucked away when catching good lift.
 
#8
With the SS design, there is apparently a considerable amount of lift. Enough in fact that the standard power pod option has 4 deg. of down thrust built in. My assumption then is that, though not desirable, the small amount of additional weight from an above wing power pod might not be too much of an issue.

Again, that is an assumption. So, I'm still thinking of building it stock, then develop an attachment for adding a small motor above, or behind, the wing.
 
#9
Prop behind wing has gotten popular because it protects the prop in nearly all crashes. ;)
It also removes the prop from the camera view when doing Aerial Photography or FPV.
I am not sure that prop-behind-wing affords any more protection than prop-over-wing, and it still would not be in the way of any FPV gear.

Prop-behind-wing is definitely an advantage for FPV in terms of CG, though, because with the weight of cameras and extra batteries for FPV you actually *need* something behind the CG to balance the plane.
 

pgerts

Old age member
Mentor
#10
A motor is additional weigt that you do not want on a thermal glider.
A power pod will help you get the plane up without other assistance - but more wieght an drag.
(using for transport between thermals - NO - those old motors run on full speed until no more fuel)
With a fixed motor i will always choose a front motor with folding prop - unless with beginners ...........
I do not fly FPV but i Think i would have put it on a Twin plane if..................