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Building a Javron Cub

It would be interesting to get the weights of the D&E Aluminium struts.
They are pretty heavily but from what I have heard.
My electric trim motor is a Nissan power window motor, it is pretty compact and I would imagine the complete weight is about the same as the manual system but the nice thing is the weight is in the back.
I definitely would go with the composite floors, mine weighed half of the stock wood flooring.

Sent from my HTC Evo using Tapatalk
 
You may consider the struts that Carlson Aircraft sell. I got a set for my 90 cub and the total weight with the ends put in them are 26-27 lbs. They may be on the light side for a heavier cub. I called D&E a long time ago and they said thier struts were something like 45 lbs.
 
Bill,

Just think about your beautiful cabin in the woods, fish jumping, waiting for the fly to bite. After a nice breakfast you wander down to your cub, ready to jump over to the lake with the 28" rainbows for a day of fishing, only to find your battery dead... (master, electric short, does not matter).

Non electric mags are important
 
Bill,

Just think about your beautiful cabin in the woods, fish jumping, waiting for the fly to bite. After a nice breakfast you wander down to your cub, ready to jump over to the lake with the 28" rainbows for a day of fishing, only to find your battery dead... (master, electric short, does not matter).

Non electric mags are important

Pmags can be fired up with a 9 volt battery. Some people on the VAN's board have an underdash 9v pad that they can plug into for just this situation. Once they are spinning 1200 RPM, they dont need any outside current source.

Bill, I have a PMAG in a box, I will put it on a scale and PM you the weight tonight.
 
Bill,

Just think about your beautiful cabin in the woods, fish jumping, waiting for the fly to bite. After a nice breakfast you wander down to your cub, ready to jump over to the lake with the 28" rainbows for a day of fishing, only to find your battery dead... (master, electric short, does not matter).

I have also thought this scenario and questioned.....wait for it......

.........electric trim.

Any thoughts about handling trim with a dead batt??


Bill, I too, love this thread already. Weigh EVERYTHING!!! Good stuff.

Can't wait to hear p-mag weight!

Non electric mags are important, and P-mag handles this by the 9-volt transistor battery trick until the engine is running and the P-magnetos and alternator can boot-strap themselves (I had a very-dead battery at Valdez last spring.....photographer wanted a picture of the instrument panel and I walked away with the master left on afterward........9-volt battery allowed me to excite the alternator field and I was charging fine with this trick once I had the engine hand-propped and running. A little cord to plug into the cigarette lighter and 9-volt connector would be nice. I did it with bailing wire:lol:)
 
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FYI, Emag Pmags will self generate and fire the plugs smoothly down to 450 rpm, with the Master Off and no external electrical power.
 
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I run dual Lightspeed have about 900 hrs on them , thought about the pmag but the trouble in Valdez with the pmag made a easy decision for me stuck with the light speed only unit that's been around 20 plus years an certified on a French helicpter mikeo
 
Yes, Mike, and it was something to deal with: We had to swing our engine and replace a heat damaged P-mag the day before Valdez. P-Mags have heat-sensitive circuit boards and MUST MUST MUST be cooled, per the manual, with blast tubes directed at the cooling fins from the high pressure side of the cowling. They functioned properly once blast tubes were installed.

I am curious if anyone here spends time on the Van's RV equivalent of SuperCub.org and has any further operational knowledge of the P-Mags.

Mike, how do you insure voltage to your Lightspeed units in the event of Battery, Alternator, or other electrical system failure?
 
Yes, Mike, and it was something to deal with: We had to swing our engine and replace a heat damaged P-mag the day before Valdez. P-Mags have heat-sensitive circuit boards and MUST MUST MUST be cooled, per the manual, with blast tubes directed at the cooling fins from the high pressure side of the cowling. They functioned properly once blast tubes were installed.

I am curious if anyone here spends time on the Van's RV equivalent of SuperCub.org and has any further operational knowledge of the P-Mags.

Mike, how do you insure voltage to your Lightspeed units in the event of Battery, Alternator, or other electrical system failure?

Bob

My P-mag install manual said that blast tubes were mandatory....mine now have 900 hrs on them and haven't given me any trouble. I am assuming you added the blast tubes AFTER the P-mag failure. I hate to see them get a bad name when installed improperly. Great company and great product.

Lou
 
Bill, great thread and what will become an even better airplane.

What are you going to do about hardware? Things like lock nuts; steel, nylon, NASA, or castle nuts with a pin? Stainless or Cad-plated screws? Nylon or metal washers?

Leo Loudenslager was fanatic about cutting as much weight as possible out of his Lazar and the Shark. When rebuilding the Lazer, he would assemble a part, then hacksaw all but one thread off the end of a bolt or screw. He kept every little piece he cut off in a 5 gallon bucket that probably weighed 15 pounds by the time he was done. Ounces lead to pounds.

nkh
 
Today we needed some much needed stress relief...

so the razor knife came out and fabric started falling off my old girl. We now have one big inspection hole in the side.

As we look into the plane right now, there is a very noticeable couple of spots where dissimilar metal corrosion is incredible. Were we put the pulleys for the water rudders around the longeron, each of the brackets are corroded, and the one longeron is in really bad shape.

This was on floats starting about six years ago, and was washed out after every salt use. After beach landings I would hose it off.

My conclusion is that one should try to keep all metals the same, or have good separation.
 
I will have to reweigh the mags. I forgot the impulse coupling. If we are going to post data it needs to be accurate. So stand by for a correction.

This came from the Airframes Alaska website ( I hope they don't get upset at me for reposting it here).

The question was about a widebody fuselage....

Question: How much more does it weigh?
Answer: Each customer gets different modifications on their fuselage but in general, the wide-body frame is 12 lbs heavier than our standard fuselage. In a recent comparison, we weighed an original piper fuselage at about 95lbs. A comparable standard fuselage from us with the basic modifications for strength and safety, weighs about 109lbs*. A similarly equipped wide-body frame with steel stringers weighs in at 125lbs*. A business partner recently reported to us that a competing standard frame weighed 127lbs! *These weights include our recommended prime powder coat.


I have tried to get the weights of the Cub Crafters AL struts but I have not had much response.

Nathan - I will be watching the hardware too. Thanks for the info.

Dave - I have considered the no trim issue. I think I can live with it for one flight to get back to a repair point. I would just have to fly at the last trimmed speed for greatest comfort for a while. It is not so much for the weight savings on this item as the convenience. It is really nice to trim without having to take your hand off of the throttle. Personal preference. I would also loose all my avionics too as I will have a glass panel again to save weight. Good idea to set up a connector for the mags. I will add that to the list.

Bill
 
Kevin

No, this one is a narrow body. The last one was a widebody, and it was certainly good but in this case I think I will be just as comfortable and lighter. In addition to the weight of the bare frame you must also take into account the wider and heavier windshield, floorboards, skylight etc. I am fairly small in stature so I fit into a std. Cub fine. For others the widebody will be worth the weight and offset by the comfort.

Bill
 
Brake master cylinders up front? No rear throttle lever? 1/2 size header tank, if any? No rear control stick? For saving weight i sure wish J. Burr would chime in here and share some secerets especially on the other subject thats running now. JERRY? doug
 
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Kevin

No, this one is a narrow body. The last one was a widebody, and it was certainly good but in this case I think I will be just as comfortable and lighter. In addition to the weight of the bare frame you must also take into account the wider and heavier windshield, floorboards, skylight etc. I am fairly small in stature so I fit into a std. Cub fine. For others the widebody will be worth the weight and offset by the comfort.

Bill

Thanks Bill. You make a good point with those other items. I am a small person so I would stick with a narrow body too.
 
More info on Mag weights

The Slick 43XX series bare mag weighs 63.625 oz
The gear that goes on the shaft weighs 4.24 oz
The Impulse coupling weighs 12.025 oz
The spacer for the impulse mag weighs 4.805 oz
The complete harness (both sides) 26.54 oz
(4) REM 40E plugs w/washers 15.63 oz
Total Slick package (2mags, 1 w/ impulse, harness, 8 plugs) = 210.36 oz, 13.1475pds

According to Brad Dement From the E-mag company the complete and comparable P-mag set up weighs right at 10.0 pds.

A weight savings of 3.14 pounds.

The weight savings over a Bendix set up is 6.2pds

According to Klaus Savier at Lightspeed Engineering his system is 4 pounds lighter than a mag system but that is without a backup battery which would add weight, the amount depending on the size and weight of the battery selected. No back up battery is needed with the P-mag set up (except possibly a 9 volt to get the engine started in the event of a totally dead battery). With the P-mag set up the engine will continue to run with total electrical failure as the P-mag has an internal alternator (that works above 400 RPM) kinda like the standard mags. The lightspeed ignition system does not have this feature so that with total electrical failure the engine would die unless you have a back up battery to keep things going until you can find a place to land.

So basically, electronic ignitions save about 3 to 6 pounds, give or take.

Bill
 
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More info on Mag weights

So basically, electronic ignitions save about 3 to 6 pounds, give or take.

Bill

There are other advantages to electronic ignition too besides the weight savings. Variable timing with RPM and manifold pressure inputs is the big one. And changing timing means a noticable improvement in fuel consumption and a no-hesitation response when the throttle is opened quickly.

Mags are 1930's technology and electronic ignition is 1980's technology.
 
Yes, I was remiss to omit the performance aspect of electronic ignition. Lou Furlong has personally enjoyed the emags/pmags for years and has also shared that info with others. I think this is pretty much a win win. Lighter and better.

Tempdog I agree that those items you mentioned will save weight but I think I will be a little closer to stock in most of those items. I want a stick in the back, throttle, and brakes too. It seems I often fly with others and I want to be able to trade landings, do a little instruction (not for hire, I know the rules), and let my pax fly a little too. But keep the ideas coming.

I had a nice visit with Jay at Javron today. I will have my fuselage completely sandblasted, use a zinc rich primer powder coat, (with emphasis on the most common corrosion areas), followed by a powder topcoat. This will cost a bit extra but I feel this will provide the best corrosion protection for an airplane that I expect to put on floats and quite possibly in salt water as well, ie the Southeast Alaska area. The fuselage will be weighed before and after for the record.

As I mentioned before Jay is interested in building fuselages a bit closer to the original plans. Plans call for all the truss members of the fuselage aft of the cockpit (excluding the longerons) to be .028 wall thickness. Seems everyone has gotten in the habit of using .035 for everything in the aft part of the fuselage. Jay has two fuselages now, identical except for the tubing thickness aft of the cockpit and they will be weighed in the next day or two. This will give us a firm and accurate measure of the weight penalty incurred for this "modification". I put modification in quotes because I am not really sure that it was ever a customer demand, but I think rather the kit companies and aftermarket fuselage guys just fell into it because it was easier to use all the same size tubing to keep things simple. I certainly understand that, but it adds unnecessary weight. We will soon find out how much. Thanks to Jay for taking the time to weigh things out and get back to basics. My fuselage will use the .028 tubing as per the plans.

Hope this helps

Bill
 
....will have my fuselage completely sandblasted, use a zinc rich primer powder coat, (with emphasis on the most common corrosion areas), followed by a powder topcoat. This will cost a bit extra but I feel this will provide the best corrosion protection for an airplane that I expect to put on floats and quite possibly in salt water as well, ie the Southeast Alaska area.

one thing I have considered, but not really done/thought threw yet, is drilling bolt hole a little larger BEFORE powder coating, since that seems to be where the corrosion starts UNDER powder coating when you have to drill ALL the powder coating out of a hole to fit bolt in..... in problem areas like tail spring mounts.....

drilling holes slightly larger will allow some powder coating still and hole and keep it sealed......

thoughts??? good idea???, bad idea????
 
Bill
I understand the idea of keeping it light. Are you also considering what happens to the C.G. when you lighten some areas? For example: Using .028" wall tubing instead of .035" in the aft section will move the C.G. forward. I know not much, but it is part of the equation. The bulk of SC improvements have a tendency to shift the C.G. forward.

Mike
My vote--bad idea. Although there is often slop in a bolt hole should it not be the best fit possible? Just assemble it with a good water proof grease to counteract the corrosion problem. Don't start with an over sized hole.
 
Mike, my thoughts follow with skywagon8a on the oversize hole concerns. I'm open to more discussion on it.

Bill, my thoughts follow with skywagon8a on the issue of light tubing in the tail and forward CG tendencies of "improved" Cubs. It takes more than just "lightweight" to have a good flying cub, in my opinion.
 
Bill,

Using the lower longerons for the baggage floor is a good idea. I'd run the floorboards flat from the firewall all the way back. You don't have to run the elevator cables under the belly. Cover them with a aluminum hat section and make the rear seat bottom removable like a A model. Less weight and a lot more usable space.

I'd see if this guy would build a A model frame to start with, and finish the turtle deck and windows like Wayne does.

Boz
 
Mike, my thoughts follow with skywagon8a on the oversize hole concerns. I'm open to more discussion on it.

ya....

I didn't mean big sloppy over size, just a few thou or so, so when you drill out most of the powder coat, there is some left in there keeping edges sealed.... no different than a bolt cad coating or chrome changing the dimension of something/taken into account.... but alas powder coating is soft.....
 
Pete - that is a risk. In a perfect world the CG will be forward in an empty config so that when you stuff all your camping gear in it you do not go aft of CG. But that also makes it a little less pleasant to fly when light as the forward CG impacts the handling and feel. I do not know where the CG will end up right now so all efforts are to keep it as light as possible in every area. Remember, this is not something new, I am only going back to the original Supercub specifications.

Mike - I agree that it hurts to disturb that nice paint and corrosion protection but I guess we are stuck. A good grease is about all we can do. I have contemplated the same thing you are talking about. Perhaps a little Vari-prime in the hole as it is very thin and might still help a little.

Boz - great to hear from you. Been a while. Thanks for the suggestions. I did not go with an A model, guess I could have, honestly did not think about it. But Javron would build you one if you wanted. This guy can, and will, build you whatever you want. No doubt he could do what you suggested. Probably a little late for me but might work for the next guy.

To all - My understanding is Jay now has drawings to a new three piece stamped rib that will be much lighter than the built up ribs from D&E, Carlson etc, and will be used in his wings. This rib will be closer to the weight of the original Piper rib, probably stronger, (I have not seen the engineering data but it was designed by an aero engineer that frequents this site) and should take several pounds out of the wings, again getting back to the original Piper weights. It make take a month or two to get the ribs in production but the wheel is in motion. So, for those of you scratch building and in need of ribs, I think you are going to have a great option available soon. I know Jay is also going to make a complete wing kit available soon using these ribs.

Great things are happening.

Hope this helps

Bill
 
Christian Sturm came for a visit. When I last visited him he had turned me on to the little Honda CT-70 minibike (also used by Addison Pemberton) as a great little way to get around the airport. I happened on to a good deal on Craigs List, so I now have..... not one, but two of these little Mini-Trail bikes to play with. These are 1993 models. Great fun, and there is quite a following of the CT-70 on the net, so web sites, forums, support, and parts are readily available. Cool new toys.

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Christian and I went to the Midwest Antique Airplane Club (MAAC) fly-in at Brodhead and got to see lots of classic airplanes like this beautiful Travelair 4000.

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I got to fly this Marquart Charger. Neat airplane and fun to fly.

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Then it was back home where we spent a little time playing with the Hatz.

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A great time. I am fortunate indeed to have Christians friendship and I am thankful for his help after my little "splash and stop". (a different way to do a "touch and go").

Bill
 
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Hi Bill, I have a friend of mine who was at Brodhead in his Travel Air. From what he has told me about it in the past, it sounds like a magical place. That is a cute Hatz you have there Bill, the way the front cowl tapers to the engine reminds me of a Travel Air. What engine do you have?

P.S., Those wing ribs sound great!
 
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