Raptor Composite Aircraft

HomeBuiltAirplanes.com

Help Support HomeBuiltAirplanes.com:

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,416
Location
North Carolina
Building something that doesn't work is valuable only as a learning experience. Peter should swallow his pride at this point and find a competent person to design a proper fix. With suitably detailed instructions, maybe he could perform the necessary work. It's hard for all but one of us to say exactly what that fix could be. A good look at the aircraft is needed...
 

wsimpso1

Super Moderator
Staff member
Log Member
Joined
Oct 18, 2003
Messages
6,684
Location
Saline Michigan
Install a small hydraulic cylinder that is matched to a small hydraulic cylinder on the rudder ends. You can use those little aluminum cylinders that are used for machine processing (pneumatic control) and they can handle the forces required in this application with hydraulic fluid in them. If a power assist was needed a small Oildyne pump with an accumulator tank will handle that problem.

Each cylinder will be about 1 lb. and as to the weight of the fluid within 1/4" OD hose. It's a wash to the control cables, the sheath and the steel brackets.

This way there would be no slop as the cylinders will be positive displacement to the slave cylinder.
Might work fine when new, but he still has to design it and install it in what he views as a completed airplane. He might or might not have room to fit the components and hardlines, and access is terrible for that work. Next up is that the ailerons are usually linked together. Even when ailerons are neutral, they are both lifting a little. In little airplanes we put in a complete circuit and then actuate the circuit. Yeah, airliners and tactical aircraft use hydraulically driven actuators. They also have sensors, pumps, reservoirs, and computers running them, redundant operation schemes, yadda, yadda, yadda, all designed to handle the many failure modes possible. Now maybe you can justify a closed circuit for each side, but when you go to sell it... well most of us have plenty of fussy hydraulics just operating our brakes.

Billski
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,079
Location
Port Townsend WA
Peter has fussy hydraulics in the rudder foot pedal adjusters. Incredibly complex. (in the control system video)
I don't think simple was a priority.
 

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
368
Location
San Rafael, California
Might work fine when new, but he still has to design it and install it in what he views as a completed airplane. He might or might not have room to fit the components and hardlines, and access is terrible for that work. Next up is that the ailerons are usually linked together. Even when ailerons are neutral, they are both lifting a little. In little airplanes we put in a complete circuit and then actuate the circuit. Yeah, airliners and tactical aircraft use hydraulically driven actuators. They also have sensors, pumps, reservoirs, and computers running them, redundant operation schemes, yadda, yadda, yadda, all designed to handle the many failure modes possible. Now maybe you can justify a closed circuit for each side, but when you go to sell it... well most of us have plenty of fussy hydraulics just operating our brakes.

Billski
Yes, but your thinking long term and we all know that this aircraft is short term as even peter has made reference to changes on the production models.

He needs a solution for this plane as it’s got some problems as we’ve all read. Short of a mechanical pull rod, he’s got few options.

The cylinders could be mounted under the dash. Come to think of it, does a proof of concept need dual controls?

There’s plenty of space in the rear for the slave.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,079
Location
Port Townsend WA
I would recommend he go back to the original aileron cables and pulleys for this prototype. Fix that springy pulley mount.

Then in the future try to "simplicate and add lightness".
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,127
Location
Thunder Bay
Seems to me since there are already holes drilled in the keel and a good supply of 1/4” steel, fab up a steel pulley mount for the keel section and return to cables. Or, you know, maybe knock out some math instead of just slamming progressively beefier parts in there until it works.
 

AIRCAB

Well-Known Member
Joined
Feb 6, 2015
Messages
68
Location
Vancouver Island
There are numerous manufacturers of push_pull cables (morse) type. You can buy high quality, teflon lined , for superior operation. If directly exposed to moisture, they will wick water and freeze, like in a machinery application. They are used lot,s in marine, with little to no issues. Also, the higher quality ones have little slop!
 

Tiger Tim

Well-Known Member
Joined
Apr 26, 2013
Messages
3,127
Location
Thunder Bay
What would it take to quietly build an improved fuselage and swap it in, converting the current fuse into a luxurious final interior mock-up to cart to shows for further fundraising? Regular scheduled behind the scenes YouTube videos would make it a little harder to stay sneaky but at this point I wonder if that’s the only way to even begin to recover.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,050
Location
Australian
and a good supply of 1/4” steel,
Does he have any left, I think he's used it all ... :p


What would it take to quietly build an improved fuselage and swap it in, ... I wonder if that’s the only way to even begin to recover.
Good plan, has been done before, but I'm pretty sure you need money and staff to accomplish that.
 

rbarnes

Well-Known Member
Joined
Aug 28, 2015
Messages
81
Location
Texas
Latest vid is up ... and ..... Well cable in a tube was a big fail .... next up Fly By Wire Raptor o_O ... "because hey it worked on the RC model"
 
Last edited:

Tom Nalevanko

Well-Known Member
Joined
Oct 10, 2007
Messages
1,324
Location
Alpine, WY
Latest vid is up ... and ..... Well cable in a tube was a big fail .... next up Fly By Wire Raptor o_O
FBW with sloppy mechanical backup seems like a crazy solution. Peter simply has poor aircraft design thought processes. There has to be a way for a rigid pulley setup even if partially external to the fuselage. A lot might have to be redone later but, at least, a lot would be learned in some initial flights without putting the test pilot at undue risk.

Best,

Tom
 

Justin Case

Member
Joined
Dec 13, 2019
Messages
12
Exactly. A partially external linkage system would indicate a focus on flying. A home brew FBW is going to bog down in months of tinkering...that is really in the realm of fantasy.
 

cheapracer

Well-Known Member
Log Member
Joined
Sep 8, 2013
Messages
6,050
Location
Australian
Dual system hydraulic, it's the simple and obvious choice.

A billion vehicles move about everyday without failure (clutch and brakes), simple hydraulics are as safe as.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,416
Location
North Carolina
Dual system hydraulic, it's the simple and obvious choice.

A billion vehicles move about everyday without failure (clutch and brakes), simple hydraulics are as safe as.
Those are push only, with no hydraulic resistance when you aren't using them. Hydraulic flight controls need to be irreversible and bidirectional. That is a different kettle of barracuda to car brakes.

I could come up with a system that worked, but it would be way heavier and more complex than cable and pulleys.
 

BBerson

Well-Known Member
HBA Supporter
Joined
Dec 16, 2007
Messages
13,079
Location
Port Townsend WA
Cable stretch? That's why cables need to be pre-tensioned to 40 pounds in a rigid system. The pulleys are on ball bearings so the pre-tension has almost no drag. Cables disconnecting and adjusting are obviously not ideal in a glider that needs the wings removed every flight, so they use push-tubes with quick connects. But this isn't a glider.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,416
Location
North Carolina
Oh Gods, are we really looking forward to a protracted and unsuccessful FBW development program because Peter cannot 'design' a suitable cable system? This should beggar belief. But with Peter, it doesn't... Someone with a clue needs to sneak to the hanger one night and fit a working system while someone else distracts Peter.

I am not willing to be the distraction!
 
Last edited:

Rik-

Well-Known Member
Joined
Sep 13, 2019
Messages
368
Location
San Rafael, California
Those are push only, with no hydraulic resistance when you aren't using them. Hydraulic flight controls need to be irreversible and bidirectional. That is a different kettle of barracuda to car brakes.

I could come up with a system that worked, but it would be way heavier and more complex than cable and pulleys.
Not entirely. There is a manual steering helm "capilano" that is human power'd power steering but still full hydraulic steering and it's got feed back when you stop being the power in the power steering.

Your way overthinking a simple solution. If you can move it without being a super human with a cable the same can be done hydraulically just as easily and reliably.
 

pictsidhe

Well-Known Member
Joined
Jul 15, 2014
Messages
7,416
Location
North Carolina
My day job is with hydraulic machinery. Trust me, I know a vast number of ways that it can go wrong, some of which I've been told are not possible! I would never put hydraulic primary controls on my own small aircraft and I naturally repel water! I don't need to overthink this...

1. It leaks. You need the surface to be in a definite position relative to the stick. That requires active feedback or you are up a very smelly creek without a paddle in short order. That is beyond a simple system. It needs a servo system. Skip that, you can have the stick on a stop, the surface can, and will, drift anywhere. The only variable being the speed at which it happens.

A cable system is several orders of magnitude easier to accomplish. Someone who cannot design a simple cable system has a zero chance of designing a hydraulic system.
 
2
Top