Lowrider LSA

Sky,

Very interesting video and it sure makes you wonder why leading edge slats/slots aren't on every wing...cost and complexity I suppose. The different shapes sure go to show there were pretty advanced aerodynamic studies underway long before NASA came along. It would have been interesting to compare leading edge devices with VG's and see how much they really benefit airflow and keep it on the wing top at high AOA. VG's are certainly cheaper and easier to employ than the slats/slots.

My gear legs are much more vertical than the ones used on the Ballancas so I'm not sure if it's possible to get any real lift from them even with an airfoil shape. I'll be happy with just getting rid of the drag. I'm still playing with how to get 0.020 2024 bent just right before I cut larger chunks of material. The smaller pieces are much easier to bend correctly and I'm using poster paper to make patterns. I still think there needs to be some substructure to support the fairing on the gear legs. I think using the 1/4" tube will provide the support but then just using fabric instead of the 2024 seems to be the best solution for ease of construction. I do like the idea that the fairing can be removed or opened up for inspection or in case there is an issue with brake lines.

Thanks for sharing the video and pictures!!

There are lots and lots of NACA reports and videos on line for the viewing on all sorts of stuff aviation. Back when EAA started producing publications (early 1960s) other than the magazine they put out several booklets that were reprints of early aviation aerodynamics and structures. Lots of good stuff. Most of what we know today relative to our Cub type of aviation was documented in the first half of the last century. Yes there are some newer developments, but the basics were all here then.

You're right Sky, I have stolen some really good videos from EAA that I made into presentations when I was teaching ground school and CAP cadet training. It's always easier for kids to learn from movies and it took some of the load off me in trying to explain things.

One problem I find in NASA stuff is they are very elementary or so complex I can't understand them...maybe it's just me.

OK....I've tried acetone, mineral spirits, alcohol, soap and hot water and my fingernails and nothing will seem to take the Stewart's glue off my little iron. I'm really glad this stuff sticks really well but not to my iron. Is there a secret solution someone familiar with the process might want to share with me??

MEK will cause it to curdle up and if you rub it around it will take it off-- your iron that is. I wouldn't be putting it on your hands, especially your fingernails. I bought a bunch of the wine colored scotch brights and just about wore the sole off my little iron cleaning it. I found that if I turned it up it cleaned better than when cold.

To this same point, no one has been able to give me a good (read logical) answer as to the process to prep the fuselage of a aircraft previously done with Stewart's? Anyone out here have any first hand knowledge? Not that I need to do it, but if there is a way to wholesale remove the glue I like to know what it is. And no, burning it off won't work, especially if your powder coated.

Use an rubber belt dresser

Thanks Doug and Bear!!

I thought about MEK but I don't keep the stuff around unless I need it. I'd have never guessed a belt dresser...live and learn from those smarter than me!!

Does anyone know where to get the list of parts needed to rebuild a MA-4 SPA carb? I need the one piece venturi for sure.

Being EX you can do a lot of work with the one pice venturi to make it flow better. If you do be prepared to drill out the nozzle. I would not do any cab mods without a 4 cylinder EGT/CHT. Small changes on baffling, intake, carb, and most anything else can have huge effect on your CHT/EGT temps. From what I have seen on cubs that have them I would not build a cub without one. Stock or modified.
DENNY

Thanks Denny!

I was planning a single lead EGT/CHT but I suppose the 4 cyl would give a lot better info.

Do you know where there is info related to the mods for the venturi? I've done lots of auto and motorcycle carbs and the Marvel is dead simple, but I'd like to do some studying and learning before I start.

Or, any thoughts on the use of throttle bodies or fuel injection systems? I used a computer control system on a '49 CJ-2A jeep I rebuilt that was made by Holley that went on a 350 Chevy I built and it had an altitude compensator. That was 15 years ago so there must be other newer injection systems out there that would work on an 0-320 in an airplane. Any ideas for a reasonable price???

Lowrider
The 4 cylinder EGT/CHT is the way to go! otherwise you have to land switch probes (drill new hole in exhaust) than repeat flight test just to see how things are running. Than pull carb drill nozzle and repeat. with 4 more test flights. It helps with finding fouled plug also only take a few seconds with mag check to see cold cylinder. Do a search google search on venturi modification supercub.org and you will find some stuff form 06 I think the time frame was.
DENNY

Low, I am a fan of fuel injection and electronic ignition for better fuel economy and the elimination of carburetor ice. The electronic ignition gives smoother running and starting than mags.
This is a combination of both system.
http://www.flyefii.com/ https://www.youtube.com/watch?v=4UcepyteB1o

I had these folks overhaul my fuel injection system. I am a pleased customer. www.AirflowPerformance.com They also build injection systems for experimentals.

Are you able to mount a fuel pump on your -H engine? If not you will need a full time electric pump or some ingenuity.

Also don't even think about a single point EGT/CHT. All cylinders or nothing. The advantages are numerous.

I'm on board with 4 by sensors.

Unk on mech fuel pump. Electric will require an alternator for sure.

I'll give those folks a call and see what they have to say. I was planning on Light SPeed ignition but an integrated system would be better if it included FI. Any thoughts on Ellison throttle body?

Check out this throttle body,

http://rotectbi.com

Thanks Knuckles!!

Interesting and it will run on auto gas unlike the Ellison TB. You would think Ellison would upgrade their products to handle car gas.

I sent an email to Rotec for price and which model would fit my application best.

Rotec responded quickly and in some detail...portion is below Thoughts???:

Rotec are pleased to announce the release of its new Mk2 series of TBI. Like the previous series the Mk2 range will continue to cover 34,40 and 48 mm diameter bore sizes at the same horse power ranges. Also the same variety of engine mounting will be retained, ie -R, -S, -2, -3, -4, -4/5. From the small VW right through to the O-540, we have them all covered.

The Mk2 series offers the same reliable performance and follows the exact same principles as the Mk1 series. The main differences are that we have now incorporated the metering regulator which was previously a separate item. On the Mk2 the fuel metering regulator is integral with the main throttle body.

We have also moved the idle mixture screw to the opposite side of the unit and away from the throttle cable thus making adjustment easier and more accessible.

We have also developed a different slide sealing system and the slide seals are now longer in length and captivated by roll pins as opposed to pesky start clips.

We have also added some etched decals around the unit to help the user identify the various functions and adjustments required set up and operate the unit.

The Mk2 series TBI is identical in its flange to flange length as the previous model, the new unit has been designed to be very compact and with the complete metering regulator now built in, yet the transverse length has only increased by a ¼”.

Our unit is almost identical to the Ellison which we tested and were impressed with. So we decided to make our own which we think is even better! Certainly a lot cheaper and spare parts are worth only a few bucks. Reason for this is, unlike the Ellison unit, we make the entire unit in-house whereas they shop out most of the job.

The Rotec TBI is a very simple system that works so well. Remember this system is NOTHING like the Aero carb or other Posa derivatives which are, to be frank, impossible to set up and downright dangerous.

The Rotec TBI is set up free, just organize your throttle and mixture cable. You will have full mixture control from a properly metered, single point mechanical fuel injection throttle body. The dynamic metering device is the secret, this constantly adjusts fuel pressure in relationship to engine power and fuel demand. The Posa types DON’T do this.

Auto gas is ok. Avgas is ok. No problems at all with auto gas, but you must keep the fuel lines covered with a sleeve to keep them cool and away from any potential vapor lock caused by excessive heat - our unit has the ability to clear vapor lock whereas the Ellison does not have a flow valve bi-pass like ours does. Our unit has a primer system built in which basically overrides the flow control valve opening fully which is great for priming and also for clearing any vapor lock. (Not that we have seen any to date nor have our customers reported any instances of VL) .

Gravity feed is ok too, but if you intend on doing aerobatics then you will need a simple low pressure fuel pump - either driven off the engine or an electric boost pump.

I have already purchased one for my supercub

If you go single cylinder injectors you should be able to tune the injector to the cylinder!!! that is what GAMI does with the continenals. I think that is best bank for the buck power wise.
DENNY

Knucles,

Did you buy the Mk2, size 4? Do you have it in hand and if so, how does the quality look?

Denny,

Agreed. There is certainly a lot of fine tuning that can be done with integrated systems. I also like the simplicity of the single throttle body and a programable ignition system to match spark to power needs. What to do, what to do?

Got side tracked with other projects but in the mean time I ordered the Rotec TBI. They are going to hold off on my warranty until I mount it as long as it's within 12 months of purchase. Nice folks to deal with and I look forward to getting the TBI in hand and I have good feelings about it's performance.

Also primed 1st cross coat on my tail feathers and I need to get my cargo trailer conversion done and out of the shop so I can build a paint booth before I go any further. Retirement is so full of things to do...recon trip to Ainsworth Hot Springs in BC next week...so many things to do and so little time!!

Daylight Savings time and Spring are going to happen soon so I'm getting ready to switch over to shorts...soon as the weather cooperates.

Question for you Stewart's System users...I'm getting orange peel in very limited and different areas while using Ecoprime on my tail feathers. Here's what I did...

1st coat, used their cleaner rinsed with clean water twice and wiped down with alcohol and shot 1st coat. I got large (2"x12") patches of orange peel for no apperant reason.

2nd coat, sanded out the orange peel and wiped down twice with alcohol and got spotty areas of orange peel in different places than before and less severe.

3rd coat, sanded out the orange peel and wiped down with alcohol 3x and got very faint orange peel in yet other places.

4th coat, sanded out the orange peel and wiped down with alcohol twice and got no orange peel.

In each case, I wore nitrile glove and had the individual parts hung up in an area where there was very little chance of being touched. I would suspect oil or some contamination on the surface but I can't figure out where it came from and why it appeared in different places. I suspected that I didn't get their cleaner removed on the first coat so I didn't use it again. I seem to have overcome the problem on the tail feathers but I really don't want to go thru this again on the fuselage fabric...sanding this mess was no fun.

ANY thoughts please.

The only trouble that I had was with the top coat. That turned out to be ambient temperature related. Are you doing this with low ambient temperatures? Low 60s or less?

Is the orange peal in Eco prime? Did you do the three cross coats of eko fill first? One with brush than two with spray? At the seminar a couple weeks ago we were told eko prime wasn't used unless you wanted a lighter tint over eko fill and than only a light coat. All the issues of orange peal we saw were due to moving too slowly with the gun their by applying too heavy a coat . We only saw the orange peal slightly on top coats that were applied too slow. If you now have 4 coats of eko prime over the three coats of eko fill you have way too much paint on there. We got real good success in the seminar by applying light, relatively fast coats.
Marty57


Sent from my iPhone


On Mar 16, 2015, at 7:10 AM,

Sky,

Yip...shop temp is between 62F and 64F with humidity usually around 40%. It seemed to go on fine and eventually the orange peel went away at the same temps. I'm hoping top coat will be this summer when temps are in the 80's or higher.

Marty,

Yes, white primer is for bright orange top coat. Ecofill went on fine and per video...very little sanding needed. I would have only used one each cross coat if the orange peel had not occured. When I sanded it smooth I needed an additional coat to cover it uniformly or the fill would have shown thru the top coats. Probably more primer than needed but it is very uniform now. I tried to keep the coats thin.

Maybe I should do the orange paint with the peel effect!!

Make sure the filter at the guy is clean, or new. Same thing happened to me, a clean filter solved the problem

Thanks Tim.

I'm running a new filter on the gun and air is thru a dryer so I think I'm good there.


FedEx just left after dropping off a box from Australia...contents below:



I must say I'm impressed with the machining and overall quality of the Rotec throttle body. Now, if it works as well as it looks I'll be very happy. It sure is dead simple compared to a carb. and cost just a little more than a rebuilt MA 4 SPA and I still have my carb to sell which was working when removed but should be rebuilt I believe. Anyone interested please let me know.

Tim said:

Make sure the filter at the guy is clean, or new. Same thing happened to me, a clean filter solved the problem

Click to expand...

What Tim says... I would suspect contamination from your lines... Clean filters, drain water traps, etc.... I have two water traps on my air system...

Brian

Well, I thought I was OK with air but it certainly wouldn't hurt to add another water trap. I'll do that before I do anymore painting. Thanks Brian!

how long did you weight on your first coat from the water wipe to spraying? could your orange peal aeras be from left over moisture? i did my last 2 cubs with stewarts and never seen any orange peal with the eco fill or prime but on the first part i shot i found gun speed and distance makes a huge difference in the out come, so i painted a few boxes to get it down. FWIW i also got a much better top coat finish by painting horizontally. for someone like Mr.Stewart with tons of painting under his belt vertically is not a problem but i was and still am terrified of getting runs and found i was much more relaxed painting in the horizontal.