Bolivia 4-Place Build

[Gordon Misch]

Understood - For that reason I had a couple conversations with the manufacturer re signal shielding, including sending them pics. They said it is fine. I felt like this location is better protected from crash damage. Thanks -

[wireweinie]

Google up the term 'Faraday cage'.

Web

[Gordon Misch]

Yes, I'm familiar with that. The extent of enclosure matters. But I know you know that.

[wireweinie]

The main difference between yours and Mr. Pierce' is, his antenna is above the ferrous metal tubing. Your appears to have tubes above, below, and to both sides.

You do what you're going to do. You're the one flying that thing. I just want to make sure the BEST info is there to be considered. As I said above, there is no such thing as 'good enough' with safety equipment. Do you want your last conscious thought to be 'Man, I hope that thing works'?

Web

[Gordon Misch]

Thanks for your input. My biggest concern is one I don't know how to address, and is one that would apply at least equally, if not more, to Steve's installation. That is if the plane is upside down, the antenna's ground plane is between antenna and satellite. Also, in Steve's installation there is more metal between antenna and sky if upside down. Can you shed light on how that would work? I'm ignorant on that.

I realize that the extent of Faraday screening depends on the size of apertures in comparison to wavelength, and that it becomes more significant when aperture size is significantly smaller than wavelength (~74 cm for 406 MHz).

(FWIW on my certified plane the antenna is an external whip on top of the fuselage. It's ideal when right side up, but subject to damage and increased Faraday screening if upside down.)

[Gordon Misch]

The following is from the manufacturer's installation instructions, pg 42. https://www.eltechnolgies.com/_files...eb6120f910.pdf

One method is to install the antenna inside the fuselage. The signal will radiate through thefabric. It is important, however, to choose the location carefully. The samerestrictions, not shadowing or masking the signal by metal obstructions, still apply. Aircraftstructures such as tubing or ribs do not generally constitute an obstruction. The ground plane must be grounded to the aircraft ground.

[frequent_flyer]

Do you want your last conscious thought to be 'Man, I hope that thing works'?

Given the rather low rate of ELT activation in crashes that does seem like a valid concern regardless of how good the antenna installation is.

For what it's worth - CubCrafters ELT antenna on the FX-3 is totally enclosed by fuselage frame and fabric. They claim to have performed a sucessful COSPAS/SARSAT test with that installation.

It may be interesting to compare radiated signal strength for antenna outside fuselage and inside fuselage with the same ground plane. Not technically difficult to do but would take a while to get enough points to construct a good polar plot.

[BC12D-4-85]

In times of old when 406's weren't sold we had portable 121.5 ELT's. Most were cockpit mounted. If needed they could be quickly removed and used outside the aircraft. Now there's some ELT's that are pretty much hard mounted in places that are not readily accessible. Plus they may not have a separate antenna that could be attached when removed if the main one or coaxial cabling is compromised from damage or fire. It might be time to rethink how we would ensure the ELT functions as expected.

Gary

[wireweinie]

It may be interesting to compare radiated signal strength for antenna outside fuselage and inside fuselage with the same ground plane. Not technically difficult to do but would take a while to get enough points to construct a good polar plot.

Agreed.

I've mapped out radiation patterns with coms and they are rarely symmetrical. There always seem to be lobes at certain clock positions around the antenna.

I can imagine a test run for FAA eyes. The incentive to accept the first (only?) positive results would be immense.

Web

[wireweinie]

In times of old when 406's weren't sold we had portable 121.5 ELT's. Most were cockpit mounted. If needed they could be quickly removed and used outside the aircraft. Now there's some ELT's that are pretty much hard mounted in places that are not readily accessible. Plus they may not have a separate antenna that could be attached when removed if the main one or coaxial cabling is compromised from damage or fire. It might be time to rethink how we would ensure the ELT functions as expected.

Gary

Disagree only slightly. Even the new 406's can be made portable with a little thinking involved. There are portable antennas that will physically fit almost any ELT. And they work well, even if the ELT manufacturer claims that the ELT is only 'legal' with their antenna. Any antenna will function correctly IF; it is made for the specific frequency band (in this case, it needs to be made for 406 mhz and 121.5 mhz) and it connects to the ELT with a matching connector.
The other thing to remember is some brands, like Artex, have a jumper wire inside the ELT wire harness connector. If you remove this jumper, the ELT will NEVER activate no matter conditions or switch position. If you pull one of these from a wreck, cut the wire harness , leaving a few inches of wire hanging on the connector on the front of the ELT, and it will still activate/function.

Web

[BC12D-4-85]

Aircraft Spruce and likely others sell portable ELT antennas. Typically they have a female BNC connector and can be used on 121.5 and 406 Mhz. Some ELT's may require different antennas/connectors. I'm suggesting the owner/operator familiarize themselves with potential portable operation before the event.

Gary

[mvivion]

My opinion for what it is worth. I am not convinced the square tip wing, or extended wing, actually makes a difference. To the best of my knowledge no one has ever done a comparison. The whole reason I had those wings is that I intended to try to do a comparison evaluation. The problem is no one (to my knowledge) has changed out ONLY the wings (ie one variable) and done a serious flight test evaluation. The same airframe has never had both sets of wings. In every case an airplane is built, then the owner/builder lauds the performance of the square tip wing with no true comparative data. He is comparing it to a completely different airplane.
The only way to find out if there is a performance difference is to fly the exact airframe with both sets of wings, controlling the variables as much as possible, and doing a controlled flight test. Not just flying it around and saying "it flies better".
I do not know which wing is better and frankly I do not believe anyone else does either. It is just another Alaska "old wives tale" until properly tested.

My opinion only

Bill

Bill,

I flew a Super Cub with extended wings and droop tips, stock flaps and ailerons for several years at work. Floats much of the year, wheels the rest. Ran engine past tbo, and plane received a factory reman O-320. The next year, Maintenance had me bring it to ANC for recover in fall. Management wanted to get rid of the extended wings, and I didn’t argue, so a new set of wings were installed on the plane. To the best of my recollection, nothing else was done to the plane during recover. This was a 1969 plane, bought new by FWS and never wrecked.

I flew that plane, with stock wings, for about another year, mostly on floats.

There were two notable differences in that aircraft: First, it took a notably longer distance to get off the water, when heavy. The lake I operated off was narrow, so easy to see difference. No scientific tests done, but takeoff distance increased by over 100 feet, at least, and maybe more. Second, the airplane, with extended wings and original aileron location had very poor roll authority. I flew that thing in a lot of turbulence, and after a while, you realized the stick didn’t do much. With stock wings, roll authority was much better, very noticeable.

About the same time, a friend had his SC rebuilt, also on floats. His wings were extended, but ailerons were moved to the tips, and flaps extended. It too had an O-320. I flew that plane some, and it performed on takeoff very close to the plane I flew when it had long wings. But, and this was a big but, it had roll control. I was wishing we’d kept the long wings and done the aileron/flap mods.

Im not a test pilot, by any stretch of the imagination, but I flew that plane, day to day, working it, in all sorts of loads and missions, with a lot of low level maneuvering flight. I much preferred flying the stock wing to the long wings, with stock ailerons, even though takeoff performance clearly suffered. At the time, we were operating these aircraft as “Public Aircraft”, and our outfit “suggested” using 2050 GW. In fact, we operated some heavier than that.

I never did a comparison of takeoff distances on wheels, but I don’t think the long wings really helped performance much on wheels. Roll authority still sucked, though.

Floatplane performance really benefits from two things: wing and thrust. Talk to anyone who’s flying a Skywagon with Wing X on floats.

Again, totally unscientific observations….take them for what they’re worth.

MTV

[mvivion]

On the subject of ELTs: I installed a 406 from ACK some years ago. The G-Switch failed in the transmit mode, no accident required. I disconnected the ELT from its external antenna, and left it lying in the baggage compartment of my Cessna 170 while I went to find tools to remove the battery. The nice Major from RCC called (again) to remind me that my ELT was still transmitting. I responded with its condition and location. His response: “No matter, we’re still receiving its signal, including its GPS location. ELT was connected to portable GPS when it first activated.

So, successfully emitting through an aluminum structure.

Your mileage may vary.

It is salient to understand that the 406 signal goes out at a MUCH higher power than 121.5 signal did. The 406 is a pulse every 50 seconds (I think), so, while more power output, it doesn’t use as much battery as 121.5 did, transmitting at much lower, but continuous power out.

MTV

[ak49flyer]

Web- I think the jumper on the Artex is only to enable the g-switch. The elt can still be turned on manually.

[wireweinie]

I've 'made contact' from a bench in a hanger. I still wouldn't depend on that setup if I was bleeding.

The Artex ELT 345 manual says one 5 watt pulse every 50 seconds. But don't forget that the 121.5 signal is still continuous out.

Web

[wireweinie]

Web- I think the jumper on the Artex is only to enable the g-switch. The elt can still be turned on manually.

You're right. It's a change from the older ones. Not a bad change though at least when we consider using it as a portable. The next time I have a 345 on the test rig, I'll verify that.

Web

[mvivion]

I've 'made contact' from a bench in a hanger. I still wouldn't depend on that setup if I was bleeding.

The Artex ELT 345 manual says one 5 watt pulse every 50 seconds. But don't forget that the 121.5 signal is still continuous out.

Web

Correct, at much lower power out….250 milliwatt??

MTV

[wireweinie]

A whopping 50 mw. Lol

But it's only for the last part of the search. For the guys on the ground, in the brush looking for the wreckage. In good terrain maybe less than a mile range?

Web

[DJ]

Here is what we got for visible progress.

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[DENNY]

Is the low point in that fuel line going uphill to the sump???
DENNY

[DJ]

The options are pretty limited. I should have cut off the sump tabs and welded them lower. In 3 point it really isn't too bad. I'll try to get a better picture

[DJ]

Because of the reinforcing tubes under the rear seats the fuel line routing is challenging.

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[Steve Pierce]

I take it the left door gets in the way of running it like a stock Super Cub? Maybe run it under the front seats like Eddie Trimmer does in his left door STC for the Pacer, it mimics a Maule.

[DJ]

Yes the left door comes down very low. There may be better ways to do this. Airframes welded in sump points in the belly so we started from those. Looks like Kirk may run them under the left door.

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[DJ]

Left wing is done. Tail feathers on. Control cables hooked up. Brakes and lines in.

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[spinner2]

DJ, it looks like you’ll be able to use a center stick and not have interference between the stick full aft and the Cessna seats. Is this the case even with full left or right stick throw and full aft? I’ve been wondering about clearance issues with two sticks or a single in the center and Cessna seats on rails?

You're coming along nicely. Keep the updates and pictures coming.

[DJ]

We installed the tail and checked stick travel before setting the rail locations. Works just fine. I'll get some pictures.

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[DJ]

This is with the seats all the way forward. I'm about 6ft and I will use the second or third hole back at least. Hole spacing is 1 inch.

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[DJ]

Wall clearance... I would have liked to push them inboard another inch. Notice the rails do not point straight at the pedals.. These seats ended up 3/4 inch outboard of the Airframes location. I hope it feels natural.

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[Scott A]

Silly question - is that the standard way Airframes Alaska is doing the brake master cylinders? Seems the whole unit is in the way with them outboard instead of reversed and inboard like standard Cub? My foot would always be hitting the pedal and unit (flying with heels on the floor).

[frequent_flyer]

Wall clearance... I would have liked to push them inboard another inch. Notice the rails do not point straight at the pedals.. These seats ended up 3/4 inch outboard of the Airframes location. I hope it feels natural

I doubt the offset will bother you. I have over 1,000 hours in the PA-28 which has pedals well offset from seat center. It looks wierd but it doesn't bother me flying it.

I do wonder where you will put your feet with that brake location.

[Steve Pierce]

Silly question - is that the standard way Airframes Alaska is doing the brake master cylinders? Seems the whole unit is in the way with them outboard instead of reversed and inboard like standard Cub? My foot would always be hitting the pedal and unit (flying with heels on the floor).

I thought the same thing. I remember seeing one of Paul Claus's 2 place Cubs with front brakes only but I think it was offset more.

[frequent_flyer]

Brake problem goes away with toe brakes - I know, love them or hate them, but they work fine on almost every current production airplane.

[DENNY]

Silly question - is that the standard way Airframes Alaska is doing the brake master cylinders? Seems the whole unit is in the way with them outboard instead of reversed and inboard like standard Cub? My foot would always be hitting the pedal and unit (flying with heels on the floor).

If you are used to flying toe brakes, it is a good ideal to fly duck foot (heal inboard and toes turned out) for 50-100 hours to get your body used to that position. You should be landing with the heels on the brakes working the rudder with the balls of your foot, kind of reverse of a Cessna. Once you get used to it it won't matter what you are flying your feet will just do the right thing. DENNY

[ak49flyer]

It’s a non-issue. I flew an airframes 4-place with brakes just like this and didn’t think about it vs stock cub. I think the angle of the pic maybe makes it seem worse; I don’t remember the master bodies being in the way at all. But I have long legs and my feet always naturally sit right above the brake and pedal in a cub- I can’t envision how you’d contort to not have your heel over the brake...?

[KevinJ]

-18 with single controls……

[DJ]

Yes Airframes had tabs welded in this position. I wanted to do something like this with my matco masters.



The structure wasn't there to make it work. I would have needed to cut out Airframes tabs and add tubes. I surrendered to advice from others who recommended sticking to bolt on options as much as possible for speed.

I really didn't like the look of the Airframes setup after bolting it in but sitting in the seat made it feel okay.

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[DJ]

Used to be a Whelen A555. I had this around with the original Halogen bulb but wanted an LED so this was my $6 idea.



Admiring the wings for the first time.



Aileron cables going in.



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[DJ]

The gascolator bracket got twisted up in the accident and I needed a new one. I texted Brian at Steve's aircraft asking if the one Spruce sells will fit. Next thing I knew he had mailed me his custom one for free! The Steve's gascolator is one of the best parts I bought for the Cub after fighting with the cheap leaking "home builders" versions.

Jonathan playing with .060 Polycarbonate sheet today.[/ATTACH]

[DJ]

Goofing around. The Becker radio and transponder were a close fit down at the bottom of the panel but everything worked out.

Started on the windshield install today.

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