Quantcast

Flea style "Piojo Flying MiniBike"

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,278
Location
Thunder Bay
Fritz, if you haven’t binned the whole concept yet maybe just make a bunch of RC test articles and find out for real what works and what doesn’t.
 

poormansairforce

Well-Known Member
Joined
Mar 28, 2017
Messages
1,005
Location
Just an Ohioan
Aerowerx is right, for the corresponding wing which goes down the ailerons must go up to push the wing down, so we pull the whole wing half down.

So the pushrods needs to be crossed at the stick.
Or attached ahead of the wing pivot point.
You need to look at it again and follow it through its motion. I don't know if the throw amounts are correct or if the forces are viable....
 

Dennis K

Member
Joined
May 23, 2014
Messages
19
Location
Portsmouth, NH USA
This control method pivoting the wing halves independently as elevators and ailerons has been successfully used on R/C model slope soarers for years. It's called wingerons or pitcherons depending on the number of functions utilized and is similar to the arrangement used for a butterfly tail. Here's a Utube video example in action (notice the degree of control).
 
Last edited:

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,601
Location
Marion, Ohio
You need to look at it again and follow it through its motion. I don't know if the throw amounts are correct or if the forces are viable....
I still don't see it.

Could you possibly redraw with the deflection, using the same dimensions for all the components, and in the proper relationship?

Another thing I wonder about is that the push-pull force is being applied at an angle to the wing. Doesn't that require a lot more force than if it is at a 90 degree angle?
 

Victor Bravo

Well-Known Member
Joined
Jul 30, 2014
Messages
7,699
Location
KWHP, Los Angeles CA, USA
I had a wingeron slope glider. Worked fine, but it required a very large steel rod to pivot the wings, and serve as the main center section spar. I am guessing that the same type of steel rod or heavy tube would scale up to be somewhere around 75-100 pounds on a full-size man-carrying aircraft where it would be expected to take 4G while still not bowing or bending the rod (and locking the roll control). Seems like it would be a high price to pay. Any one of you high brain function types care to validate or de-bunk that 75 pound wild guess? For sake of discussion, let's say you have an 18-20 foot wingspan and a 600 pound gross, 5 inch thick wing section, and you cannot afford for the pivot tube to bend more than a couple of degrees.
 

erkki67

Well-Known Member
Joined
Feb 18, 2010
Messages
2,169
Location
Romont / Fribourg / Switzerland
The main load is going over the rotation point of the wing fuselage connection and at the wing strutt attachment.

So the control rods can have about the same size like in standard flea.
 

Sockmonkey

Well-Known Member
Joined
Apr 24, 2014
Messages
1,909
Location
Flint, Mi, USA
I still don't see it.

Could you possibly redraw with the deflection, using the same dimensions for all the components, and in the proper relationship?

Another thing I wonder about is that the push-pull force is being applied at an angle to the wing. Doesn't that require a lot more force than if it is at a 90 degree angle?
Ok, here ya go.

The amount of force the pilot needs to apply doesn't seem to be that much, but the proportions and exact positioning can be tweaked a bit.
 

Topaz

Super Moderator
Staff member
Log Member
Joined
Jul 29, 2005
Messages
14,112
Location
Orange County, California
Just seems like a needless development risk that offers little perceptible benefit over simply putting ailerons on the rear wing.

Looking at this, the "benefit" is a reducing the roll-control system by 2-4 pullies and about six feet of cable. The "cost" is breaking the spar at the middle of the span, large pressure leaks through the centerline when rolling - with the attendant increase in induced drag, and potentially wrenching control forces on the stick in gusty conditions.

I just don't see that it's worth it, myself.
 

Sockmonkey

Well-Known Member
Joined
Apr 24, 2014
Messages
1,909
Location
Flint, Mi, USA
You know what, they're right. The forces will be far less than a cantilever wing. But there will still be bending loads in the center.
The center is supported by the A-frame struts.
Just seems like a needless development risk that offers little perceptible benefit over simply putting ailerons on the rear wing.

Looking at this, the "benefit" is a reducing the roll-control system by 2-4 pullies and about six feet of cable. The "cost" is breaking the spar at the middle of the span, large pressure leaks through the centerline when rolling - with the attendant increase in induced drag, and potentially wrenching control forces on the stick in gusty conditions.

I just don't see that it's worth it, myself.
There are other benefits. Less twisting force on the fuselage while banking. The downwash from the fore wing increases the lift on the aft wing. That's how fleas can stay level while climbing and descending. That means the half of the fore wing that deflects it's trailing edge down to increase it's lift will also increase the lift of the aft wing on that side so both contribute.
The aft wing being shorter also means that aft ailerons would have much less roll authority.
Honestly if you don't want to split the fore wing, just stick full length flapelevons on the fore wing instead of the rear one. They will still do all the things you need.
 

Aerowerx

Well-Known Member
Joined
Dec 1, 2011
Messages
5,601
Location
Marion, Ohio
Ok, here ya go.


The amount of force the pilot needs to apply doesn't seem to be that much, but the proportions and exact positioning can be tweaked a bit.
Thank you, but I still don't get it.

As you tilt the control stick to the left, the right ball joint goes HIGHER than the neutral position, as you show. So how can it pull DOWN on the right wing?

Unless there is an angle at first where it starts to pull down, stops, and then with further stick travel, starts to push up. NOT a good idea, IMHO.

And, as Topaz said. Needless development. Aren't there some split wing aircraft that already do this? And it is certainly possible to do this without ball joints.

[Edit] Ah, I think I see what you are doing. In the neutral position the pushrods are supposed to be exactly at 45 degrees?? You are taking a known design for a elevon mixer and making it bigger. The problem is that you would have to use steel tubing for strength. This will be heavy, and I also think that such long unsupported pushrods will flex and possibly lead to disastrous wing flutter!
 

poormansairforce

Well-Known Member
Joined
Mar 28, 2017
Messages
1,005
Location
Just an Ohioan
Another thing I wonder about is that the push-pull force is being applied at an angle to the wing. Doesn't that require a lot more force than if it is at a 90 degree angle?
Let me be clear, I'm not advocating or rejecting this idea. I just wanted everyone to be on the same page. The forces due to the angles will be different, that is certain
 

Topaz

Super Moderator
Staff member
Log Member
Joined
Jul 29, 2005
Messages
14,112
Location
Orange County, California
... Honestly if you don't want to split the fore wing, just stick full length flapelevons on the fore wing instead of the rear one. They will still do all the things you need.
That's actually the far better idea, if one simply can't handle ailerons on the rear wing for some reason. Rutan tried this on one of the EZE prototypes and had very poor results, but then the canard on the EZE's was a very small surface, relative to the wing. It would take a lot of calculation and probably some additional testing, but the fact that a "flea" derivative has much larger front wing might make this possible. You'd still have the added complexity of a mixer, but that's an individual choice.

All this said, I'd personally just put ailerons on the rear wing.
 

FritzW

Well-Known Member
Log Member
Joined
Jan 30, 2011
Messages
3,896
Location
Las Cruces, NM
What's the benefit of a split wing over ailerons? I can see three significant down sides to a split wing with no real benefit.
Making a mixer isn't an issue. The issue is weather or not it makes sense to put a split wing on a Piojo.

What would be the advantage?
 

Sockmonkey

Well-Known Member
Joined
Apr 24, 2014
Messages
1,909
Location
Flint, Mi, USA
If you wanted to stick with just two-axis then a split wing gives that with a single control system. Plus, it gives an easy way to fold the wing just by unhooking the outer struts since the wing is already in two halves.

Rear wing ailerons only make sense if you make them elevons and have the fore wing be fixed.
 
Top